Method for preparing ceramic shell for precision casting

Abstract

A method for preparing a ceramic shell for precision casting. The method comprises: S1, smearing the exterior of a wax pattern with corresponding layers of ceramic shell slurry layer by layer, wherein a ceramic shell to be dried is obtained at a corresponding layer each time after the smearing of the ceramic shell slurry is completed; S2, putting said ceramic shell at each corresponding layer into a vacuum rapid drying system for a vacuum rapid drying treatment, and after the drying of the ceramic shell at the layer is completed, smearing same with a subsequent layer of ceramic shell slurry, wherein during the vacuum rapid drying treatment, image data of the ceramic shell to be dried is first acquired and subjected to model structure analysis so as to obtain the position, orientation and depth of a deep hole in the ceramic shell to be dried, same are sent to a fan set control module, the fan set control module performs fan set control analysis according to the position, orientation and depth of the deep hole in the ceramic shell to be dried and controls the starting and stopping and / or control parameters of each fan set according to an analysis result, and the drying time of all portions of the integral ceramic shell to be dried tends to be identical by means of vacuumizing a vacuum drying chamber and / or restoring the chamber pressure and controlling the starting and stopping and / or control parameters of all the fan sets; and S3, waiting for the completion of the drying of the ceramic shells at all the layers to obtain a ceramic shell for precision casting. On the basis of retaining the inherent advantages of a thick-slurry ceramic shell, the preparation method effectively overcomes problems present in the thick-slurry ceramic shell.

Description

TECHNICAL FIELD

[0001] The disclosure relates to the technical field of precision casting, and particularly relates to a method for preparing and drying a ceramic shell for precision casting.BACKGROUND

[0002] Precision casting is a casting method compared with a traditional casting technology, and can obtain a relatively accurate shape and high casting accuracy. A technological process of the precision casting is as follows: firstly, a wax pattern is made, which has a consistent size and shape with a to-be-cast product; then, a ceramic shell is formed on a surface of the made wax pattern, and then, the ceramic shell is subjected to dewaxing (the wax pattern inside it is removed after melting); and finally, metal is poured into the ceramic shell subjected to dewaxing, and after the metal is cooled and solidified, the ceramic shell is broken and removed, such that an obtained casting is a required product.

[0003] In the technological process, preparing of the ceramic shell is crucial, and its quality determines quality of castings. At present, a common method for preparing a ceramic shell is: a shell molding method. Specifically, a water-soluble silica sol shell-preparing method is generally used. In this method, in a case that the ceramic shell is prepared, refractory materials are used to prepare different slurry and sand, and slurry and sand are alternately and gradually piled up on a surface of a wax pattern layer by layer, so as to manufacture the ceramic shell having a required thickness. Thus, a structure of the ceramic shell can be divided into a surface layer, a transition layer (second layer), a supporting layer (back layer), and a sealing layer. Only one surface layer, one transition layer and one sealing layer are provided, while a plurality of supporting layers are generally provided.

[0004] According to a concentration of ceramic shell slurry in a preparing process of the ceramic shell, the ceramic shells are generally divided into a thick slurry ceramic shell and a thin slurry ceramic shell. As its name implies, the thick slurry ceramic shell has a high concentration of ceramic shell slurry. Compared with the thin slurry ceramic shell, the thick slurry ceramic shell has the following main advantages: 1, Each layer of ceramic shell has a relatively great thickness, resulting in a relatively high supporting force. In this way, fewer layers of thick slurry ceramic shells can achieve a supporting force of the ceramic shell that can be achieved by more layers of thin slurry ceramic shells, and complexity of a process is reduced. 2, A surface layer of the ceramic shell has a high density, and a problem of casting penetration rarely occurs.

[0005] However, when ceramic shells are prepared in the prior art, the main reason why the thin slurry ceramic shells are still selected in most cases is that the thick slurry ceramic shells have the following insurmountable problems: 1, Due to a high concentration of slurry, sand can hardly penetrate into an entire slurry layer during sand coating, resulting in an uneven state in which coating sand is polymerized on a surface layer and an interior is void. Thus, strength of the ceramic shell is uneven, and a sand-free part is prone to cracking during drying, leading to puncture and misfire of castings. 2, Permeability of the ceramic shell is poor, and a problem of poor exhaust during casting can be caused, such that a recess surface on a casting surface caused by bubbles is likely to appear, which influences casting accuracy. 3, A breaking strength coefficient is high. Although the high breaking strength coefficient is conducive to preparing of a dense surface layer, providing a sufficient supporting force for a casting process. However, the high breaking strength coefficient of the entire ceramic shell can make it difficult to break the shell and take the casting after casting is completed. It is easy to damage the casting when the shell is broken violently, resulting in decline in casting accuracy. Thus, on the premise of ensuring that the ceramic shell has a sufficient supporting force, making the ceramic shell have a lower breaking strength coefficient has always marked a technical improvement direction in the field of precision casting. 4, Although the thick slurry ceramic shell has a low water content, water molecules have great movement resistance, so thick slurry has even longer drying time than thin slurry. In addition, in a case of involving castings having deep holes, it is difficult to make the drying time of all portions of the ceramic shell tend to be identical. Generally, after a deep hole portion of the ceramic shell is dried, the other portion of the ceramic shell may be overdried, resulting in cracking of the ceramic shell.

[0006] However, single-layer thickness expansion of the thin slurry ceramic shell is limited. In a case that a breaking strength coefficient is low, it is necessary to increase a thickness of the ceramic shell by increasing a number of layers, so as to provide a sufficient supporting force. This requires repeated slurry application, which makes the process more complex. The drying time of the ceramic shell is prolonged with an increase in the number of layers, thus significantly reducing preparing efficiency. Meanwhile, in a case of involving deep hole castings, how to make the drying time of all the portions of the thin slurry ceramic shell tend to be identical and how to complete drying in a short time are also technical problems to be solved.SUMMARY

[0007] In order to solve problems in the prior art, the disclosure provides a method for preparing a ceramic shell for precision casting. The method includes: S1, smearing an exterior of a wax pattern with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained for each corresponding layer each time after smearing of the ceramic shell slurry is completed; S2, putting the to-be-dried ceramic shell of the corresponding layer into a vacuum rapid drying system for a vacuum rapid drying treatment, and smearing, after drying of the ceramic shell of the corresponding layer is completed, same with a subsequent layer of ceramic shell slurry, where during the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical; and S3, obtaining the ceramic shell for precision casting after completion of drying of the ceramic shells at all the layers.

[0008] Further, the vacuum rapid drying system includes: a vacuum drying chamber, a vacuum pump, and a control system. The vacuum pump vacuumizes the vacuum drying chamber. The vacuum drying chamber is internally provided with a drying frame. A to-be-dried ceramic shell is arranged on the drying frame so as to be dried. The vacuum drying chamber is internally provided with at least two groups of fan sets having different wind directions around the drying frame.

[0009] The control system includes: a vacuum drying control module and a fan set control module. The vacuum drying control module vacuumizes the vacuum drying chamber and / or restores chamber pressure. The fan set control module controls starting and stopping and / or control parameters of all fan sets, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0010] Further, the vacuum drying chamber is internally provided with a first air blower set on a top of the drying frame. A bottom of the drying frame is provided with a second air blower set. The drying frame is provided with a third air blower set arranged on an opening and closing door of the vacuum drying chamber along a section of the vacuum drying chamber. The drying frame is provided with a fourth air blower set and a fifth air blower set at two sides of the vacuum drying chamber in an axial direction respectively.

[0011] Further, the vacuum drying chamber is internally provided with an adjustable member at an opposite side of the third air blower set. The adjustable member is: a condenser or a sixth air blower set.

[0012] Optionally, the vacuum drying chamber is provided with a controller assembly. The controller assembly receives and sends a control signal to the fan set control module, so as to control starting and stopping and / or the control parameters of each fan set.

[0013] Further, a controller includes: at least one of a knob controller, a key controller, a touch screen controller, and a toggle switch.

[0014] Optionally, the vacuum drying chamber is internally provided with a three-dimensional detection mechanism. The three-dimensional detection mechanism drives a scanning device to move along an X axis, a Y axis, and a Z axis.

[0015] The scanning device at least includes: a photographing device. The photographing device is configured to acquire image data of the to-be-dried ceramic shell.

[0016] The control system includes: a ceramic shell analysis module. The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0017] Further, the three-dimensional detection mechanism includes: two X-axis guide rails that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber and located at two sides of the drying frame respectively, and a Y-axis guide rail horizontally arranged along a section of the vacuum drying chamber. The two X-axis guide rails are provided with first displacement devices movable along the X-axis guide rails respectively. The Y-axis guide rail is fixedly arranged between the two first displacement devices and is driven to move along the X-axis guide rails by the two first displacement devices. The Y-axis guide rail is provided with a second displacement device movable along the Y-axis guide rail. The second displacement device is vertically provided with an electronic control telescopic device that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device is fixedly provided with the scanning device through an electronic control pan-tilt. The first displacement devices, the second displacement device, the electronic control telescopic device and the electronic control pan-tilt are connected to the control system in a signal manner separately.

[0018] Further, the control system includes: a scanning device control module. The scanning device control module is configured to control movement of the two first displacement devices, the second displacement device, the electronic control telescopic device and the electronic control pan-tilt, such that the scanning device photographs / scans the to-be-dried ceramic shell in all directions, and image / scanning data of the to-be-dried ceramic shell is obtained.

[0019] Further, the model structure analysis includes image analysis as follows: firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of the to-be-dried ceramic shell; then, comparing the acquired image data with the outer contour model data, and determining a spatial orientation of the to-be-dried ceramic shell currently hanging in the vacuum drying chamber; and finally, determining a current position and orientation of a deep hole in the to-be-dried ceramic shell according to the spatial orientation of the to-be-dried ceramic shell, and outputting the current position and orientation of the deep hole in the to-be-dried ceramic shell and depth data corresponding to the deep hole.

[0020] Further, the scanning device further includes: a scanning and distance measuring device. The scanning and distance measuring device is configured to measure a distance of the to-be-dried ceramic shell from the scanning device in real time.

[0021] The model structure analysis includes: step 1.1, scanning, by the scanning and distance measuring device, a surface n of the to-be-dried ceramic shell in all directions according to a preset line, and acquiring a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device; step 1.2, connecting end points of the distance measuring data set G n , and obtaining a digital surface m of the surface n of the to-be-dried ceramic shell; step 1.3, performing graphic analysis on the digital surface m of the to-be-dried ceramic shell by combining the image data, and determining a basic surface, a protruding surface and a recess surface of the digital surface m; step 1.4, computing a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk; step 1.5, using C mk-b >K 2 as a deep hole and C mk-b >K 3 as a through hole, where K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell; step 1.6, counting positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell and a depth H mc corresponding to each deep hole, where c denotes a natural number of the deep hole in the digital surface m; step 1.7, repeating step 1.1 to step 1.6 until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell are counted, and determining an orientation X mc of the deep hole according to the surface n where the deep hole is located; and step 1.8, outputting data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell.

[0022] Further, in step 1.3, a method for acquiring the basic surface, the protruding surface and the recess surface includes: step 1.3.1, acquiring the image data corresponding to the digital surface m of the to-be-dried ceramic shell, and splicing the image data so as to obtain an image surface R; step 1.3.2, performing element identification on the image surface R, and obtaining an element zone rn-m on the image surface R, where rn denotes a sequence number of the element zone in the digital surface m; step 1.3.3, adjusting the digital surface m to have a same orientation and a similar size to the image surface R; step 1.3.4, using an element zone rc-m having a maximum continuous area as the basic surface, where the rc-m belongs to rn-m; step 1.3.5, acquiring distance measuring point data of an element zone of each non-basic surface, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point; and step 1.3.6, using the element zone as a boundary, and connecting adjacent recess point and protruding point to form the recess surface and the protruding surface.

[0023] Further, the three-dimensional detection mechanism is provided with an electronic control telescopic device. A tail end of a telescopic end of the electronic control telescopic device is fixedly provided with a scanning device through an electronic control pan-tilt.

[0024] Optionally, the electronic control pan-tilt includes: a fixing platform fixed to the electronic control telescopic device and a rotating platform rotatably connected to the fixing platform and rotating along a vertical axis relative to the fixing platform. The rotating platform is rotatably connected to a fixed end of a second electronic control telescopic device through a reducer. The reducer controls the second electronic control telescopic device to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device is fixed to the scanning device.

[0025] Further, the model structure analysis further includes: step 2.1, controlling a scanning and distance measuring device to move to the position of the deep hole according to the position of the deep hole; step 2.2, acquiring depth measurement data of a plurality of deep holes by adjusting orientations of the scanning and distance measuring device relative to the deep holes; and step 2.3, correcting depth data H m-c of an original deep hole with depth measurement data having a maximum depth, and obtaining corrected data H m-c '.

[0026] Further, the scanning device further includes: an infrared temperature measuring device. The control system includes: a drying process analysis module that acquires a measurement quantity of the infrared temperature measuring device for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell is completed.

[0027] The drying process analysis includes: measuring an internal temperature T of the deep hole regularly or continuously; and making a curve Q v of deep hole temperature T v -drying time t. In response to determining that a curve segment conforming to a preset curve rule appears in Q v , it is indicated that drying of the to-be-dried ceramic shell is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell.

[0028] Further, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0029] Further, in response to determining that a plurality of to-be-dried ceramic shells of a same batch are provided, temperatures of all the deep holes of all the to-be-dried ceramic shells are measured one by one. In response to determining that drying of more than L% of the to-be-dried ceramic shells is completed, it is determined that drying of the entire batch of to-be-dried ceramic shells is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells of the batch d.

[0030] Further, the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells having deep holes in surfaces, the following method is used: step 3.1, acquiring a total number D 0 of all the deep holes of the to-be-dried ceramic shells, and acquiring a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells faced by the fan sets p, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber; step 3.2, computing k S-p% =D p / D 0 *100%, where k S-p % denotes control parameters of the fan sets p; and step 3.3, repeating step 3.1 to step 3.2 until k S-p % of all the fan sets is obtained.

[0031] In a case that all fan sets p face the to-be-dried ceramic shells having no deep holes in surfaces, the following method is used: computing k F - p %=[1-D 0 / (D 0 +1)]*100%, where K F-p % denotes control parameters of the fan sets p; and sending, by the fan set control module, obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0032] Further, the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells having deep holes in surfaces, the following method is used: step 4.1, acquiring a total number D 0 of all the deep holes of the to-be-dried ceramic shells, and acquiring a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells faced by the fan sets p, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber; step 4.2, acquiring k S-p % from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p; and step 4.3, repeating step 4.1 to step 4.2 until k S-p % of all the fan sets is obtained.

[0033] In a case that all fan sets p face the to-be-dried ceramic shells having no deep holes in surfaces, the following method is used: acquiring k F-p % from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells, where the k F-p % denotes the control parameters of the fan sets p; and sending, by the fan set control module, obtained k S-p % and k F-p %of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0034] Further, a method for inputting k S-p % and k F-p% into the control parameter database includes: step 5.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber 1 in a simulation apparatus; step 5.2, presetting a deep hole distribution of different to-be-dried ceramic shells for drying training, and determining the control parameters k S-p % and k F-p %in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4; and step 5.3, repeating step 5.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p %, and storing the deep hole-control parameter relation set in the control parameter database.

[0035] Further, at least two fans are arranged and mounted in the fan set. The fan set control module synchronously or independently controls the fans in each fan set.

[0036] Further, the fan set control analysis further includes: step 6.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device; step 6.2, recording, by the scanning device, a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell in a model structure analysis process; step 6.3, acquiring a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p, where e denotes a natural number of the fans in the fan set p; step 6.4, counting a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p; and step 6.5, computing k up-e %=(D up-e / D up )*k S-p %.

[0037] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0038] Further, the fan set control analysis includes: step 7.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device; step 7.2, recording, by the scanning device, a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell in a model structure analysis process; step 7.3, acquiring a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p, where e denotes a natural number of the fans in the fan set p; step 7.4, counting a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p; and step 7.5, acquiring k up-e % of the corresponding fan from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0039] The fan set control module sends obtained k up-e% of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0040] Further, a method for acquiring the k up-e % includes: step 8.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber in a simulation apparatus; step 8.2, presetting a deep hole distribution of different to-be-dried ceramic shells for drying training, and determining a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells; and step 8.3, repeating step 8.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of D up -D up-e -k up-e %, and storing the deep hole-control parameter relation set in the control parameter database.

[0041] Further, the vacuum rapid drying system includes: a first data transmission module, a local database module, and a remote system module.

[0042] The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0043] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set.

[0044] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0045] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0046] Further, the vacuum rapid drying system includes a second data transmission module.

[0047] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0048] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0049] Further, the scanning device includes: a thermal imager. A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: step 9.1, performing, by the thermal imager, real-time thermal imaging photographing on the to-be-dried ceramic shell along with the scanning device in a drying process of the to-be-dried ceramic shell, and sending an image obtained through real-time thermal imaging photographing to the control system; and step 9.2, determining, by the control system, whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and performing, in response to determining that there is the zone T, the following determination and operations: reducing, in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T; enhancing, in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T; and enhancing, in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T.

[0050] Further, the preset low-temperature threshold is 12°C-15°C. The preset high-temperature threshold is 26°C-28°C. The preset first drying time is 1 min-3 min. The preset time threshold is 30 s-60 s.

[0051] Further, a method for the vacuum rapid drying treatment includes: in a case that a surface layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 750 mmHg-720 mmHg within 5 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 750 mmHg-720 mmHg to the normal pressure within 5 s; and circulating the above process until drying of the surface layer is completed; in a case that a transition layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 720 mmHg-680 mmHg within 7 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 720 mmHg-680 mmHg to the normal pressure within 7 s; and circulating the above process until drying of the transition layer is completed; in a case that a supporting layer is dried, the method comprises the following steps: step 10.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 10.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 10.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 10.6, repeating step 10.4 and step 10.5 until drying of the supporting layer is completed; and in a case that a sealing layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 120 mmHg-90 mmHg within 40 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell to the normal pressure within 120 s; and circulating the above process until drying of the sealing layer is completed.

[0052] Further, at least three supporting layers are sequentially arranged from the transition layer to the sealing layer.

[0053] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers is used and includes the following steps: step 11.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 11.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; step 11.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and step 11.6, repeating step 11.4 and step 11.5 until drying of the first layer of the supporting layers is completed.

[0054] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers is used and includes the following steps: step 12.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 12.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; step 12.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and step 12.6, repeating step 12.4 and step 12.5 until drying of the second layer of the supporting layers is completed.

[0055] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers is used and includes the following steps: step 13.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 13.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 13.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 13.6, repeating step 13.4 and step 13.5 until drying of the third layer of the supporting layers is completed.

[0056] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0057] Further, the vacuum rapid drying system includes: a vacuum drying chamber, a vacuum pump, and a control system. The vacuum pump vacuumizes the vacuum drying chamber. The vacuum pump is in communication with the vacuum drying chamber through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve. The vacuum drying chamber is in communication with an air tube. The air tube is provided with a second electronic control valve.

[0058] The to-be-dried ceramic shell is put into the vacuum drying chamber for the vacuum rapid drying treatment.

[0059] The control system controls opening and closing of the vacuum pump, the first electronic control switching valve and the second electronic control valve, so as to implement method steps of the vacuum rapid drying treatment.

[0060] Further, the vacuum rapid drying system further includes: a vacuum tank. One end of the vacuum tank is in communication with the vacuum pump through a second connecting tube. The second connecting tube is provided with a third electronic control valve. The other end of the vacuum tank is in communication with the vacuum drying chamber through a third connecting tube. The third connecting tube is provided with a fourth electronic control valve. Further, a method for performing vacuum drying on the supporting layers and the sealing layer further includes an instantaneous pressure reduction operation. The instantaneous pressure reduction operation includes: firstly closing the fourth electronic control valve before pressure reduction, and performing pumping on the vacuum tank to a low vacuum state in advance; then opening the fourth electronic control valve during pressure reduction, such that the vacuum drying chamber is in communication with the vacuum tank, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally simultaneously extracting, by the vacuum pump, gas-phase components in the vacuum tank and the vacuum drying chamber, closing the fourth electronic control valve and the first electronic control switching valve after a vacuum degree in the vacuum drying chamber satisfies a preset target, and meanwhile, continuing to extract, by the vacuum pump, the gas-phase components in the vacuum tank until the vacuum tank is in the low vacuum state.

[0061] Further, on the basis that the method for performing vacuum drying on the supporting layers and the sealing layer further includes the instantaneous pressure reduction operation: a method for performing a vacuum rapid drying treatment of a first layer of the supporting layers is used and includes the following steps: step 14.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank vacuumized; step 14.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 14.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and making the vacuum tank continue to be vacuumized; step 14.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank vacuumized; step 14.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and making the vacuum tank continue to be vacuumized; and step 14.6, repeating step 14.4 and step 14.5 until drying of the first layer of the supporting layers is completed.

[0062] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: step 15.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank vacuumized; step 15.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 15.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and making the vacuum tank continue to be vacuumized; step 15.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank vacuumized; step 15.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and making the vacuum tank continue to be vacuumized; and step 15.6, repeating step 15.4 and step 15.5 until drying of the second layer of the supporting layers is completed.

[0063] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers is used and includes the following steps: step 16.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank vacuumized; step 16.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 16.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and making the vacuum tank continue to be vacuumized; step 16.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank vacuumized; step 16.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and making the vacuum tank continue to be vacuumized; and step 16.6, repeating step 16.4 and step 16.5 until drying of the third layer of the supporting layers is completed.

[0064] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer is used and includes the following steps: step 17.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, keeping the vacuum tank vacuumized; step 17.2, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 120 s; and making the vacuum tank continue to be vacuumized; and step 17.3, repeating step 17.1 and step 17.2 until drying of the sealing layer is completed.

[0065] The disclosure at least has one of the following beneficial effects: 1, On the basis of retaining inherent advantages of a thick slurry ceramic shell, the disclosure effectively solves problems present of the thick slurry ceramic shell, and provides a thick slurry ceramic shell excellent in average layer thickness, high in air permeability, uniform in sand coverage and excellent in breaking strength coefficient. 2, The disclosure can make the drying time of all the portions of the ceramic shell tend to be identical through manual control or automatic analysis control, and especially in a case involving a deep hole structure having great uniform difficulty in drying, the drying time of the deep holes and the surface can be effectively balanced, and an optimal result is obtained. 3, The disclosure has abilities of remote control and remote sharing, and can synchronize an optimal fan control method to all vacuum drying systems, thus significantly reducing trial and error cost when enterprises dry various types of ceramic shells and improving enterprise benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a schematic structural diagram of a vacuum rapid drying system of the disclosure; FIG. 2 shows a schematic diagram of an internal structure of a vacuum drying chamber of the disclosure; FIG. 3 shows a schematic diagram of a local structure of a three-dimensional detection mechanism of the disclosure; FIG. 4 shows a schematic diagram of a local structure of a Z axis of a three-dimensional detection mechanism of the disclosure; FIG. 5 shows a schematic structural diagram of an electronic control pan-tilt of the disclosure; FIG. 6 shows a schematic structural diagram of a scanning device of the disclosure; FIG. 7 shows a schematic structural diagram of an illustrative ceramic shell; FIG. 8 shows a schematic diagram of scanning the ceramic shell shown in FIG. 7 with a scanning device of the disclosure; FIG. 9 shows a schematic diagram of a temperature-time curve of a preset curve rule for determining whether drying is completed of the disclosure; and FIG. 10 shows a schematic structural diagram of another illustrative ceramic shell.

[0067] In the figures: 1, vacuum drying chamber; 101, first air blower set; 102, second air blower set; 103, third air blower set; 104, fourth air blower set; 105, fifth air blower set; 106, air tube; 107, second electronic control valve; 108, adjustable member; 2, three-dimensional detection mechanism; 201, X-axis guide rail; 202, Y-axis guide rail; 203, first displacement device; 204, second displacement device; 205, electronic control telescopic device; 206, electronic control pan-tilt; 2061, fixing platform; 2062, rotating platform; 2063, reducer; 2064, second electronic control telescopic device; 207, scanning device; 2071, photographing device; 2072, thermal imager; 2073, scanning and distance measuring device; 2074, infrared temperature measuring device; 3, drying frame; 301, guide rail; 302, hanger support; 303, roller; 304, ceramic shell hanger; 305, hook recess; 4, to-be-dried ceramic shell; 401, deep hole; 402, holding part; 5, vacuum tank; 6, fourth electronic control valve; 7, third connecting tube; 8, vacuum pump; 9, third electronic control valve; 10, first electronic control switching valve; and 11, hook.DETAILED DESCRIPTION OF EMBODIMENTS

[0068] The disclosure is described in further detail below with reference to the accompanying drawings. It should be noted that the description is merely illustrative, and is not intended to limit the scope of the disclosure. Further, description of well-known structures and technologies is omitted in the following description, such that concepts of the disclosure are prevented from being unnecessarily confused.

[0069] The disclosure illustratively provides a method for preparing a ceramic shell for precision casting. The method includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry.

[0070] During the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0071] S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0072] The disclosure makes the drying time of all the portions of the to-be-dried ceramic shell tend to be identical by adjusting the control parameters of each air blower in different side directions of the to-be-dried ceramic shell. Especially, in a case involving a deep hole structure having great uniform difficulty in drying, the drying time of the deep holes and the surface can be effectively balanced.

[0073] The disclosure illustratively provides a vacuum rapid drying system. As shown in FIG. 1, the vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0074] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with at least two groups of fan sets having different wind directions around the drying frame 3.

[0075] The control system includes: a vacuum drying control module and a fan set control module. The vacuum drying control module controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10, and the second electronic control valve 107. The fan set control module controls starting and stopping and / or the control parameters of all the fan sets.

[0076] In the vacuum drying system of the prior art, the added fan set generally uses a constant-speed running method. In order to achieve uniformity of drying, in the prior art, as shown in the prior patent technology of the applicant: CN201610416881.4, two groups of fan sets and ceramic shell rotating devices in different directions are used to make the ceramic shell continuously rotate so as to be exposed to wind in a drying process, such that balance of the drying process is improved. However, the method has the following problems: 1, In a case that a complex component having deep holes is dried, a problem that drying time of the deep holes is relatively consistent with drying time of other portions cannot be solved. That is, in a case that a complex component having deep holes is dried, the other portions of the ceramic shell may still be overdried when drying of deep hole portions of the ceramic shell is completed. 2, The ceramic shell has a certain centrifugal force in a rotation process, such that sand in the ceramic shell is likely to deviate centrifugally, especially when viscosity of slurry is low. 3, The ceramic shell needs to be rotated continuously in the drying process, which leads to a possibility of relative sliding of the to-be-dried ceramic shell, and further a possibility of colliding of the ceramic shell or slipping of a rotary disc, resulting in damage of the ceramic shell.

[0077] By means of the vacuum drying system of the disclosure, the fan set in the vacuum drying chamber 1 may be controlled accordingly through the fan set control module, such that drying degrees of all the portions of the ceramic shell may be changed by providing winds different in side directions and intensities. A windward surface of the ceramic shell having the deep hole structure has a strong wind force, which is conducive to rapid volatilization of water in the deep holes. In addition, a windward surface of the ceramic shell having no deep hole structure has a weak wind force, which prevents the portion of the ceramic shell from being dried too rapidly, such that the drying time of all the portions of the ceramic shell tends to be identical.

[0078] The disclosure illustratively provides composition of a fan set. Specifically, as shown in FIGs. 1 and 3, the vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3, a bottom of the drying frame 3 is provided with a second air blower set 102, the drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively.

[0079] The disclosure illustratively provides an additional member. As shown in FIG. 1, the vacuum drying chamber 1 is internally provided with an adjustable member 108 at an opposite side of the third air blower set 103. The adjustable member 108 is: a condenser or a sixth air blower set.

[0080] The disclosure illustratively provides a method for controlling a fan set. Specifically, the vacuum drying chamber 1 is provided with a controller assembly. The controller assembly receives and sends a control signal to the fan set control module, so as to control starting and stopping and / or the control parameters of each fan set.

[0081] The disclosure illustratively provides a controller. The controller includes: at least one of a knob controller, a key controller, a touch screen controller, and a toggle switch.

[0082] In this way, a running state of the fan sets may be controlled through off-line control. That is, the controller may select whether all the fan sets are started and a running ratio at which the fan sets run. The running ratio is a ratio of a current fan speed to a rated speed.

[0083] The method makes an overall structure of the control system relatively simple. However, in a case that the ceramic shell is dried, an operator needs to observe a direction of the deep holes of the to-be-dried ceramic shell, and control the running ratio of each corresponding fan set according to experience. A drying effect is highly correlated with an observation ability and work experience of the staff.

[0084] The disclosure illustratively provides a method for controlling a fan set. Specifically, as shown in FIGs. 1-2, the vacuum drying chamber 1 is internally provided with a three-dimensional detection mechanism 2. The three-dimensional detection mechanism 2 drives a scanning device 207 to move along an X axis, a Y axis, and a Z axis.

[0085] As shown in FIG. 6, the scanning device 207 includes: a photographing device 2071. The photographing device 2071 is configured to acquire image data of the to-be-dried ceramic shell 4.

[0086] The control system includes: a ceramic shell analysis module. The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell 4 and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell 4, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell 4 and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0087] The image data is analyzed to rapidly determine a basic structure of the ceramic shell, and whether there are deep holes and positions and orientations of the deep holes is determined, such that the fan sets facing the deep holes can be determined and controlled at a corresponding fan running ratio.

[0088] The disclosure illustratively provides a three-dimensional detection mechanism. As shown in FIGs. 1-4, the three-dimensional detection mechanism 2 includes: two X-axis guide rails 201 that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber 1 and located at two sides of the drying frame 3 respectively, and a Y-axis guide rail 202 horizontally arranged along a section of the vacuum drying chamber 1. The two X-axis guide rails 201 are provided with first displacement devices 203 movable along the X-axis guide rails 201 respectively. The Y-axis guide rail 202 is fixedly arranged between the two first displacement devices 203 and is driven to move along the X-axis guide rails 201 by the two first displacement devices 203. The Y-axis guide rail 202 is provided with a second displacement device 204 movable along the Y-axis guide rail 202. The second displacement device 204 is vertically provided with an electronic control telescopic device 205 that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device 205 is fixedly provided with the scanning device 207 through an electronic control pan-tilt 206. The first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206 are connected to the control system in a signal manner separately.

[0089] The disclosure illustratively provides a control system. The control system includes: a scanning device control module. The scanning device control module is configured to control movement of the two first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206, such that the scanning device 207 photographs / scans the to-be-dried ceramic shell 4 in all directions, and image / scanning data of the to-be-dried ceramic shell 4 is obtained.

[0090] The scanning device control module may control the three-dimensional detection mechanism of the disclosure to drive the scanning device 207 to move in three dimensions of an X axis, a Y axis and a Z axis, such that 5 surfaces of a front surface, a rear surface, a left surface, a right surface and a top surface of the to-be-dried ceramic shell 4 are scanned in all directions, and a bottom of the to-be-dried ceramic shell is scanned laterally. Thus, an image of a main structure of the to-be-dried ceramic shell 4 is obtained, such that the positions and the orientations of the deep holes of the to-be-dried ceramic shell 4 can be determined more accurately.

[0091] The disclosure illustratively provides a method for model structure analysis. The method specifically includes image analysis: firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of the to-be-dried ceramic shell 4; then, comparing the acquired image data with the outer contour model data, and determining a spatial orientation of the to-be-dried ceramic shell 4 currently hanging in the vacuum drying chamber 1; and finally, determining a current position and orientation of a deep hole in the to-be-dried ceramic shell 4 according to the spatial orientation of the to-be-dried ceramic shell 4, and outputting the current position and orientation of the deep hole in the to-be-dried ceramic shell 4 and depth data corresponding to the deep hole.

[0092] With rapid development of digital technologies in recent years, it is possible to design the to-be-dried ceramic shell through digital modeling, and the to-be-dried ceramic shell designed through digital modeling has detailed structural data. Thus, the disclosure compares the image data of the to-be-dried ceramic shell with a digital model in an actual environment, such that the positions and the orientations of the deep holes of the ceramic shell are rapidly determined through the image data of the to-be-dried ceramic shell. Then, a depth of the corresponding deep hole is acquired from the digital model, such that the positions and the orientations of the deep holes of the to-be-dried ceramic shell 4 and the depth data corresponding to the deep holes can be obtained.

[0093] The disclosure illustratively provides a scanning device 207. As shown in FIG. 6, the scanning device 207 further includes: a scanning and distance measuring device 2073. The scanning and distance measuring device 2073 is configured to measure a distance of the to-be-dried ceramic shell 4 from the scanning device 207 in real time.

[0094] The disclosure illustratively provides a method for model structure analysis. The method includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device 2073 is acquired. Step 1.2, end points of the distance measuring data set G n are connected, and a digital surface m of the surface n of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4; Step 1.6, positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell 4 and a depth H mc corresponding to each deep hole are counted, where c denotes a natural number of the deep hole in the digital surface m. Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output.

[0095] The disclosure illustratively provides a method for acquiring the basic surface, the protruding surface and the recess surface in step 1.3. The method includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0096] FIG. 7 shows a to-be-dried ceramic shell 4 including a deep hole 401. With a left front view with n=1 of six front views of the to-be-dried ceramic shell 4 as an instance, the method specifically includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n=1 of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G1 of all scanning points on the surface n=1 from the scanning and distance measuring device 2073 is acquired. Step 1.2, as shown in FIG. 8, end points of the distance measuring data set G1 are connected, and a digital surface m=1 of the surface n=1 of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m=1 of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m=1 are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Two recesses k=1 and k=2 are provided on the digital surface m=1, where internal distance measuring points of k=1 include 5 distance measuring points of b=8 to b=12. Thus, C mk-b =C 11-8 =|(L 11-8 )-(L 11-13 )|, C mk-b =C 11-9 =< |(L 11-9 )-(L 11-13 )|, C mk-b =C 11-10 =< |(L 11-10 )-(L 11-13 )|, C mk-b =< C 11-11 =(L 11-11 )-(L 11-13 )|, and C mk-b =< C 11-12 =|(L 11-12 )-( 11-13 )| need to be computed. Internal distance measuring points of k=2 include 4 distance measuring points of b=18 to b=21. Thus, C mk-b =C 11-18 =|(L 11-18 )-(L 11-13 )|, C mk-b =C 11-19 =| (L 11-19 )-(L 11-13 )|, C mk-b =C 11-20 =|(L 11-20 )-(L 11-13 )|, and C mk-b =C 11-21 =|(L 11-21 )-(L 11-13 )| need to be computed. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4. For instance, C mk-b =C 11-10 > K 2 . Thus, a recess with k=1 on the digital surface m=1 is a deep hole. Step 1.6, positions W mc =W 11 of all deep holes in the digital surface m=1 of the to-be-dried ceramic shell 4 and a depth H mc =H 11 corresponding to each deep hole are counted, where c=1 denotes a natural number of the deep hole in the digital surface m=1. The positions of W mc =W 11 are positions corresponding to distance measuring points 8 to 12, and the depth H mc =H 11 corresponding to the deep hole is a computed value of C mk-b =C 11-10 . Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output.

[0097] The disclosure illustratively provides a method for acquiring the basic surface, the protruding surface and the recess surface in step 1.3. The method includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0098] In the prior art, not all the to-be-dried ceramic shells 4 are obtained through digital model designing, or a digital model of the to-be-dried ceramic shell 4 obtained through digital model designing is not supported by the vacuum rapid drying system. In this case, the vacuum rapid drying system fails to determine whether a shadow in the image data is a deep hole through the digital model, and fails to determine the depth of the deep hole through the image data. Through the method of the disclosure, through automatic scanning and analysis, data of the positions W mc , the depths H mc and the orientations X mc of all the deep holes in the surface of the to-be-dried ceramic shell 4 may be determined through automatic analysis. In this way, the vacuum rapid drying system may acquire necessary data of the positions W mc , the depths H mc and the orientations X mc of all the deep holes in the surface of the to-be-dried ceramic shell 4, so as to perform fan set control analysis.

[0099] The disclosure illustratively provides an electronic control pan-tilt 206. As shown in FIG. 5, the electronic control pan-tilt includes: a fixing platform 2061 fixed to the electronic control telescopic device 205 and a rotating platform 2062 rotatably connected to the fixing platform 2061 and rotating along a vertical axis relative to the fixing platform 2061. The rotating platform 2062 is rotatably connected to a fixed end of a second electronic control telescopic device 2064 through a reducer 2063. The reducer 2063 controls the second electronic control telescopic device 2064 to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device 2064 is fixed to the scanning device 207.

[0100] It is difficult to scan the bottom of the to-be-dried ceramic shell 4 with a conventional pan-tilt, such that the disclosure improves a pan-tilt structure. On one hand, the scanning device 207 may scan the bottom of the to-be-dried ceramic shell 4 through the second electronic control telescopic device 2064. On the other hand, a rotating orientation of the scanning device 207 may be changed through the reducer 2063, which increases a freedom degree of scanning movement. Thus, the scanning device 207 may adapt to scanning of a more complex to-be-dried ceramic shell 4.

[0101] The disclosure illustratively provides a method for model structure analysis. Based on the model structure analysis, the method further includes: Step 2.1, a scanning and distance measuring device 2073 is controlled to move to the position of the deep hole according to the position of the deep hole. Step 2.2, depth measurement data of a plurality of deep holes is acquired by adjusting orientations of the scanning and distance measuring device 2073 relative to the deep holes. Step 2.3, depth data H m-c of an original deep hole is corrected with depth measurement data having a maximum depth, and corrected data H m-c ' is obtained.

[0102] In a case that the to-be-dried ceramic shell 4 is designed, the deep hole structure is generally designed on an axis of a model, such that the deep holes of the ceramic shell are distributed along the axis. In this way, in a scanning and distance measuring process, distance measuring laser may penetrate into the deep holes, and distance measuring data of the deep holes may be measured. Thus, the depths of the deep holes may be obtained. However, in actual work, not all the deep holes of the ceramic shell are designed along the axis, and not all the to-be-dried ceramic shells 4 are placed forward or hooked during drying. Thus, an orientation of the deep hole may deflect relative to a running axis of the scanning device 207. In this case, laser emitted by the scanning and distance measuring device 2073 cannot penetrate into the deep hole, and a measured depth of the deep hole may be wrong. In this way, accuracy of fan set control analysis is influenced, and an actual drying speed of the deep hole portion of the to-be-dried ceramic shell 4 is quite different from a designed drying speed, thus influencing drying uniformity of all the portions of the to-be-dried ceramic shell 4.

[0103] Through a supplementary method for model structure analysis of the disclosure, the scanning and distance measuring device 2073 may obtain a plurality of distance measuring data having different orientations relative to the deep holes by adjusting the orientations of the scanning and distance measuring device 2073 relative to the deep holes at the positions of the deep holes. The distance measuring data includes distance measuring point data in which the orientation of the scanning and distance measuring device 2073 is consistent with or similar to that of an axis of the deep holes. The distance measuring data is consistent with or similar to the depth of the deep hole. Thus, accuracy of the fan set control analysis can be significantly improved. In this way, a difference between the actual drying speed and the designed drying speed of the deep hole portion of the to-be-dried ceramic shell 4 is significantly reduced.

[0104] The disclosure illustratively provides a scanning device 207. As shown in FIG. 6, based on the scanning device 207, an infrared temperature measuring device 2074 is further included. The control system includes: a drying process analysis module. The drying process analysis module acquires a measurement quantity of the infrared temperature measuring device 2074 for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell 4 is completed.

[0105] The disclosure illustratively provides a method for drying process analysis. The method includes the following steps: an internal temperature T of the deep hole is measured regularly or continuously; and a curve Q v of deep hole temperature T V -drying time t is made. In response to determining that a curve segment conforming to a preset curve rule appears in Q v , it is indicated that drying of the to-be-dried ceramic shell 4 is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell 4.

[0106] The disclosure illustratively provides a preset curve rule. As shown in FIG. 9, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell 4 changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0107] In the prior art, a method for determining whether drying of the to-be-dried ceramic shell 4 is completed mainly depends on experience or several tests, such that the corresponding drying time is obtained under certain drying conditions. In response to determining that the drying time is reached, it is determined that drying is completed. However, in a case that the method is used for the to-be-dried ceramic shells 4 changing in a plurality of batches, since the to-be-dried ceramic shells 4 in all the batches have inconsistent structures, their drying time needs to be adjusted accordingly. Thus, it is necessary to test the drying time in advance, which seriously influences overall drying efficiency.

[0108] After research, the applicant finds that in the drying process of the to-be-dried ceramic shell 4, water volatilization is an endothermic process, and at an initial stage of drying, ceramic shell slurry has a high water content. Thus, a large amount of water may be volatilized at the initial stage of drying of the ceramic shell, resulting in a significant drop in temperature of the ceramic shell. After water is volatilized to a certain extent, the water content of the ceramic shell slurry decreases, and accordingly, a volatilization speed of water decreases. Thus, a temperature of the ceramic shell may gradually tend to be a drying environment temperature. When the temperature of the ceramic shell is kept at the drying environment temperature, it is indicated that almost no water is volatilized, which indicates that drying is completed. Thus, a method for determining whether drying of the to-be-dried ceramic shell 4 is completed of the disclosure is used to determine whether drying of the to-be-dried ceramic shell 4 is completed, which is only related to a temperature change curve in the drying process, and not related to a structure of the to-be-dried ceramic shell 4. In this way, each batch of to-be-dried ceramic shells 4 may be accurately dried, which effectively solves problems existing in an existing drying time control method.

[0109] Meanwhile, after research, the applicant finds that, on one hand, temperature of the ceramic shell slurry decreases with volatilization of water in the drying process, and on the other hand, water volatilization may lead to certain shrinkage of the ceramic shell (even if the ceramic shell is supported by sand). In this case, at the initial stage of drying the ceramic shell, the wax pattern may be cooled and shrink due to cooling of the ceramic shell. Thus, the ceramic shell may adhere to a surface of a shrunk wax pattern in the drying process. In a case that a temperature of the ceramic shell starts to rise, the wax pattern may expand with a temperature rise. However, a shrinkage and expansion process of the wax pattern influenced by temperature is slower than that of the ceramic shell.

[0110] If cooling time of the ceramic shell is too long, that is, a cooling range is small and drying time is too long, the wax pattern may completely shrink at a low temperature for a long time. On one hand, the ceramic shell may adhere to an obviously shrunk wax pattern, leading to obvious spatial deformation of castings of a final ceramic shell and influencing casting accuracy. On the other hand, in a case that a temperature of the wax pattern rises and the wax pattern expands, due to too great a shrinkage-expansion ratio, it is easy to break the ceramic shell solidified and attached to a surface of the shrunk wax pattern. This situation leads to failure of ceramic shell preparing or irregular spikes on a casting surface, influencing casting accuracy. Moreover, too long drying time further influences preparing efficiency of the ceramic shell.

[0111] If cooling time of the ceramic shell is too short, that is, a cooling range is too great and drying time is too short, a problem that a deep hole is not dried completely and a surface is overdried often occurs, that is, an empty window period for adjusting the drying time is very short, which is not conducive to adjustment of the drying time of all the portions of the to-be-dried ceramic shell 4. This situation increases difficulty of controlling drying uniformity of the to-be-dried ceramic shell 4.

[0112] Due to a low concentration of the ceramic shell slurry and a high water content of a thin slurry ceramic shell, less slurry may be applied during slurry application. Thus, a thickness of each layer of ceramic shell is small, and thermal conductivity is high. This situation leads to various unfavorable problems caused by too long or too short cooling time of the thin slurry ceramic shell, so control accuracy of the drying process is too high, which is difficult to implement.

[0113] However, compared with the thin slurry ceramic shell, a thick slurry ceramic shell has a higher concentration of the ceramic shell slurry and a lower water content, so more slurry may be applied during slurry application. Thus, each layer of ceramic shell is great in thickness and poor in thermal conductivity. Under a condition that a T 2 temperature defined by the disclosure is 5°C-7°C lower than a T 1 temperature, the ceramic shell may have a suitable drying speed. On one hand, the situation that all the portions of the ceramic shell are dried too rapidly such that drying progress is not easy to adjust may be avoided while efficient drying is performed. On the other hand, drying may be completed in a case that the wax pattern is not completely shrunk, and then both the wax pattern and the ceramic shell are returned to a room temperature. Thus, a problem that the wax pattern expands and cracks the ceramic shell can be avoided.

[0114] The disclosure illustratively provides a method for determining whether drying of a plurality of to-be-dried ceramic shells 4 is completed. The method includes the following steps: temperatures of all the deep holes of all the to-be-dried ceramic shells 4 are measured one by one; and in response to determining that drying of more than L% of the to-be-dried ceramic shells 4 is completed, it is determined that drying of an entire batch of to-be-dried ceramic shells 4 is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells 4 of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells 4 of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells 4 of the batch d.

[0115] In order to improve drying efficiency of ceramic shells, a plurality of to-be-dried ceramic shells 4 having a same structure are generally dried synchronously in a batch of drying process. Due to different placement or hooking methods of the plurality of to-be-dried ceramic shells 4, a degree of wind exposure of each of the to-be-dried ceramic shells 4 is different, and the drying time is varied. Thus, it is necessary to control a certain margin, and vacuum rapid drying is stopped after drying of most of the to-be-dried ceramic shells 4 is completed, such that a problem of excessive drying of most of the to-be-dried ceramic shells 4 after drying of the ceramic shells exposed to less wind is completed is avoided. The preset percentage threshold is determined according to wind difference of the to-be-dried ceramic shells 4, and is generally not smaller than 98%. In this way, after drying is completed, even if a to-be-dried ceramic shell 4 is not completely dried, a water content of the to-be-dried ceramic shell may not be too high, and drying may be continued in a later drying process such that drying is completed.

[0116] The disclosure illustratively provides a method A for fan set control analysis. The method includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 3.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 3.2, k S-p %=D p / D 0 *100% is computed, where k S-p % denotes control parameters of the fan sets p. Step 3.3, step 3.1 to step 3.2 are repeated until k S-p % of all the fan sets is obtained.

[0117] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p% =[1-D 0 / (D 0 +1)]*100% is computed, where k F-p % denotes control parameters of the fan sets p.

[0118] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0119] For instance, a total number of all deep holes in the to-be-dried ceramic shell 4 satisfies D 0 =4, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=1 satisfies D 1 =1, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=2 satisfies D 2 =1, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=3 satisfies D 3 =2, and the remaining to-be-dried ceramic shells 4 have no deep holes in the surfaces and are provided with corresponding fan sets p=4, p=5 and p=6.

[0120] In this case, the following is computed: k S − 1 % = D 1 / D 0 * 100 % = 1 / 4 * 100 % = 25 % , k S − 2 % = D 2 / D 0 * 100 % = 1 / 4 * 100 % = 25 % , k S − 3 % = D 3 / D 0 * 100 % = 2 / 4 * 100 % = 50 % , and k F − 4 % = k F − 5 % = k F − 6 % = 1 − D 0 / D 0 + 1 * 100 % = 1 − 4 / 5 * 100 % = 20 % .

[0121] Through the method for fan set control analysis of the instance of the disclosure, a running condition of each fan set may be automatically and adaptively adjusted according to the acquired deep hole distribution of the to-be-dried ceramic shell 4. In this way, wind exposure of a portion having more deep holes in the to-be-dried ceramic shell 4 is improved, and a drying speed is high, which is conducive to rapid drying in the deep holes. However, in a portion having few or no deep holes, a degree of wind exposure decreases accordingly, and a drying speed is decreased, which is conducive to synchronization with drying time of the deep holes. Thus, drying is completed in a short drying time on the basis of ensuring that drying degrees of all the portions of the to-be-dried ceramic shell 4 tend to be identical.

[0122] Moreover, the method is only related to a number and positions of the deep holes in the to-be-dried ceramic shell 4. For to-be-dried ceramic shells 4 having various types of structures, such as a standard or non-standard structure, the drying time may be preferably controlled to be short, and the drying time of all the portions of the ceramic shell may be preferably controlled to tend to be identical.

[0123] The disclosure illustratively provides a method B for fan set control analysis. The method includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 4.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 4.2, k S-p % is acquired from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p. Step 4.3, step 4.1 to step 4.2 are repeated until k S-p % of all the fan sets is obtained.

[0124] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p % is acquired from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4, where the k F-p % denotes the control parameters of the fan sets p.

[0125] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0126] The disclosure illustratively provides a method for inputting k S-p % and k F-p % into the control parameter database. The method includes: Step 5.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 5.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and the control parameters k S-p % and k F-p % in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution are determined, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 5.3, step 5.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D 0 -D p -k S-p% -k F-p % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0127] Through the method for fan set control analysis of the instance of the disclosure, a large number of deep hole-control parameter relation sets related to a comprehensive and optimal situation may be prepared in a database of the vacuum drying system through preliminary experiments. In this way, after the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 and the total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p are acquired, the corresponding fan set may be controlled with optimal k S-p % and k F-p % theoretically related to D 0 -D p according to the pre-stored deep hole-control parameter relation set in the control parameter database.

[0128] An optimal result of an experiment is as follows: under a specific deep hole relation set of D 0 -D p , the fan set is controlled to run with the control parameters of k S-p %-k F-p %, such that the drying time may be the shortest on the basis of ensuring that the drying degrees of all the portions of the to-be-dried ceramic shells 4 tend to be identical. The drying time is closely related to a size, a surface area and a surface structure of the to-be-dried ceramic shell 4, so the method needs to be determined together with a digital model structure of the to-be-dried ceramic shell 4. A standard to-be-dried ceramic shell 4 is a common component, and may be subjected to experimental simulation in advance. A non-standard to-be-dried ceramic shell 4 is a special-shaped member designed as required, and has various structural modes, which may not be covered by preliminary tests. In a case that the control parameter database lacks a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % corresponding to the special-shaped to-be-dried ceramic shell 4, the method B for fan set control analysis of the instance fails to acquire the required deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p %. In this case, the method A for fan set control analysis of the instance should be used to obtain the deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % corresponding to the special-shaped to-be-dried ceramic shell 4 after analysis.

[0129] The method B for fan set control analysis of the instance and the method A for fan set control analysis of the instance may be used separately or jointly.

[0130] The disclosure illustratively provides a fan set. At least two fans are arranged and mounted in the fan set. The fan set control module synchronously or independently controls the fans in each fan set.

[0131] The disclosure illustratively provides a method C for fan set control analysis based on a case that a fan set is internally provided with at least two fans. Based on the method A for fan set control analysis or the method B for fan set control analysis, the method further includes: Step 6.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 6.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 6.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 6.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 6.5, k up-e %=(D up-e / D up )*k S-p % is computed.

[0132] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0133] For instance, the fan set p includes two fans, which are numbered p-1 and p-2 respectively. The fans are fixed relative to the scanning starting point preset by the scanning device 207, so coordinate positions of the fans p-1 and p-2 in the three-dimensional coordinate system created in step 6.1 are also fixed. In this case, the fan p-1 may form a cylindrical air duct p-1 with a fan shaft axis as a central axis and a diameter R=100 cm in the three-dimensional coordinate system. An intersection surface of the cylindrical air duct p-1 and a corresponding surface of the to-be-dried ceramic shell 4 is a coordinate system range U p-1 covered by the fan p-1, and a number D up-1 of deep holes in U p-1 is counted. For instance, D up-1 =1, D up-2 =2, and a number D up of deep holes in the entire coverage of the fan set p is 3 for instance. Thus, the following may be computed: k up − 1 % = D up − 1 / D up * k S − p % = 1 / 3 * k S − p % , and k up − 2 % = D up − 2 / D up * k S − p % = 2 / 3 * k S − p % .

[0134] That is, in the fan set p, a fan 1 runs at a state of (1 / 3)* k S-p %, and a fan 2 runs at a state of (2 / 3)* k S-p %.

[0135] The method C for fan set control analysis of the instance of disclosure, separate control parameters of each fan in the fan set p may be obtained through computation, such that corresponding separate control of a plurality of fans in the fan set p is implemented. The method may make winds blown by the fan set p to the to-be-dried ceramic shell 4 more targeted, and make drying completion time of all the portions, especially a deep hole distribution zone and a non-deep hole distribution zone, of the to-be-dried ceramic shell 4 tend to be identical.

[0136] The disclosure illustratively provides a method D for fan set control analysis based on a case that a fan set is internally provided with at least two fans. Based on the method A for fan set control analysis or the method B for fan set control analysis, the method further includes: Step 7.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 7.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 7.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 7.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 7.5, k up-e % of the corresponding fan is acquired from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0137] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0138] The disclosure illustratively provides a method for inputting k up-e % into the control parameter database. The method specifically includes: Step 8.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 8.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution is determined. The deep hole distribution includes: an orientation and a number of the deep holes. The optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 8.3, step 8.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D up -D up-e -k up-e % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0139] Through the method for fan set control analysis of the instance of the disclosure, a large number of deep hole-control parameter relation sets of D up -D up-e -k up-e % related to a comprehensive and optimal situation may be prepared in a database of the vacuum drying system through preliminary experiments. In this way, in response to determining the coordinate system range U p-e covered by a blowing orientation of each fan in the fan set p, the number D up-e of deep holes in a coverage range of U p-e , and a number D up of deep holes in the entire coverage range of the fan set p, each fan may be controlled separately with fan control parameters corresponding to optimal k up-e % related to D up -D up-e theoretically according to the deep hole-control parameter relation set of D up -D up-e -k up-e % pre-stored in the control parameter database.

[0140] Similar to the method B for fan set control analysis of the instance, the method D for fan set control analysis of the instance is mainly suitable for the to-be-dried ceramic shell 4 having a model structure covered by preliminary simulation experiments. For the to-be-dried ceramic shell 4 having a model structure not covered by preliminary simulation experiments, the deep hole-control parameter relation set of D up -D up-e -k up-e % is obtained through the method C for fan set control analysis of the instance.

[0141] The disclosure illustratively provides a vacuum rapid drying system. The vacuum rapid drying system includes: a first data transmission module, a local database module, and a remote system module.

[0142] The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0143] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set and running result data.

[0144] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0145] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0146] For instance, if each vacuum rapid drying system is networked with the remote system module through the Internet, an optimal result corresponding to the deep hole-control parameter relation set D up -D up-e -k up-e % recorded by the local database module of each vacuum rapid drying system for a model A is B. In this case, an enterprise or apparatus manufacturer finds by experiment or chance that the control parameters in the deep hole-control parameter relation set D up -D up-e -k up-e % are adjusted to k up-e% ', and a result C superior to the optimal result B may be obtained. In this case, a new deep hole-control parameter relation set D up -D up-e -k up-e %' recorded for the model A and the corresponding optimal result C are collected centrally through the remote system module of the disclosure, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0147] Through the data synchronization method of the disclosure, optimal control parameters for a certain model obtained by an enterprise or apparatus manufacturer may be synchronized into all other networked vacuum rapid drying systems, such that an optimization degree of the control parameters for the model under a D up -D up-e condition is improved, and drying efficiency is enhanced. Thus, the disclosure can continuously optimize and improve the control parameters of the fan set and all the fans in the fan set in an actual running process, enhance overall drying efficiency, and improve enterprise benefits.

[0148] The disclosure illustratively provides a vacuum rapid drying system. The vacuum rapid drying system includes: a second data transmission module and a remote system module.

[0149] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0150] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0151] The vacuum rapid drying system of the instance may run with intervention of the remote system module, such that the vacuum rapid drying system is remotely controlled. For instance, the method can make a supplier conveniently remotely control and self-check an apparatus for a user, and improve efficiency of early apparatus adjustment and later apparatus maintenance.

[0152] The disclosure illustratively provides a drying frame 3. The drying frame includes: a ceramic shell hanger 304 configured to hang the to-be-dried ceramic shell 4. The ceramic shell hanger 304 is provided with a plurality of hook recesses 305. The to-be-dried ceramic shell 4 is hooked at the hook recesses 305 through hooks 11. A hanger support 302 is fixed to a bottom of the ceramic shell hanger 304. A bottom of the hanger support 302 is provided with a plurality of rollers 303 slidable along a guide rail 301. The guide rail 301 is fixed to a bottom surface in the vacuum drying chamber 1.

[0153] A preparing process of the ceramic shell involves repeated slurry application and corresponding drying operations. Thus, the to-be-dried ceramic shell 4 needs to be conveniently and detachably fixed to both the ceramic shell hanger 304 and the vacuum drying chamber 1. The disclosure provides a method for detachably fixing the to-be-dried ceramic shell 4 to the ceramic shell hanger 304 and the vacuum drying chamber 1. Specifically, the to-be-dried ceramic shell 4 may be hooked at the hook recesses 305 through the hooks 11, such that the to-be-dried ceramic shell 4 may be conveniently and detachably fixed to the ceramic shell hanger 304 through hooking / detachment. Then, the ceramic shell hanger 304 slides into / out of the guide rail 301, such that the to-be-dried ceramic shell 4 may be conveniently and detachably fixed to the vacuum drying chamber 1.

[0154] The disclosure illustratively provides a guide rail 301. The guide rail 301 is provided with a limiting block at one side away from an opening and closing door of the vacuum drying chamber 1. As shown in FIG. 1, the guide rail 301 is provided with a limiting block at one side close to an adjustable member 108. The arrangement can make a sliding position of the ceramic shell hanger 304 in the vacuum drying chamber 1 relatively fixed, such that a number of to-be-dried ceramic shells 4 faced by the fan set in each drying process is similar, and drying stability is improved.

[0155] The disclosure illustratively provides a scanning device 207. The scanning device 207 includes: a thermal imager 2072. A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: Step 9.1, the thermal imager 2072 performs real-time thermal imaging photographing on the to-be-dried ceramic shell 4 along with the scanning device 207 in a drying process of the to-be-dried ceramic shell 4, and sends an image obtained through real-time thermal imaging photographing to the control system. Step 9.2, the control system determines whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and in response to determining that there is the zone T, the following determination and operations are performed: in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T is reduced; in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T is enhanced; and in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T is enhanced.

[0156] The disclosure illustratively provides a preset low-temperature threshold, which is 12°C-15°C.

[0157] The disclosure illustratively provides a preset high-temperature threshold, which is 26°C-28°C.

[0158] The disclosure illustratively provides preset first drying time, which is 1 min-3 min.

[0159] The disclosure illustratively provides a preset time threshold, which is 30 s-60 s.

[0160] It is one of main to-be-solved problems of the disclosure to make drying degrees of all the portions of the to-be-dried ceramic shell 4 tend to be identical and make the drying time of all the portions of the to-be-dried ceramic shell 4 tend to be identical. Through a method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical of the instance of the disclosure, the control parameters of each fan set may be dynamically adjusted based on temperature changes of all the portions in a thermal image of the to-be-dried ceramic shell 4 in the drying process, such that the drying time of all the portions of the to-be-dried ceramic shell 4 tends to be more identical in the drying process.

[0161] The disclosure illustratively provides a method for a vacuum rapid drying treatment. The method includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0162] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0163] In a case that a supporting layer is dried, the following steps are included: step 10.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min; step 10.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s; step 10.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s; and step 10.6, step 10.4 and step 10.5 are repeated until drying of the supporting layer is completed.

[0164] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0165] An existing vacuum rapid drying technology for the ceramic shell is mainly to rapidly dry a surface layer and a transition layer through a reciprocating operation of vacuumizing and recompressing based on a thin slurry ceramic shell. A supporting layer may expand under a reciprocating high negative pressure condition, so as to form a sponge-like structure, such that a breaking strength coefficient of the ceramic shell is reduced while a thickness of the ceramic shell is increased.

[0166] Compared with the existing vacuum rapid drying technology for the thin slurry ceramic shell, a thick slurry ceramic shell should be rapidly dried under simpler control conditions theoretically due to a low water content. For instance, CN201610416881.4 discloses a vacuum rapid drying method for a thin slurry ceramic shell. "In a case that a supporting layer of the ceramic shell is dried, firstly, a sealed cavity is subjected to pumping to a vacuum state of 300 mmHg-100 mmHg within 60 s and kept for 400 s-600 s, and then the sealed cavity is subjected to vacuum deflation, such that the sealed cavity returns to a normal pressure state; then, step b is started, in which the sealed cavity is subjected to pumping to a vacuum state of 300 mmHg-100 mmHg within 60 s, and then step c is performed; the sealed cavity is subjected to vacuum deflation within 120 s in step c, such that the sealed cavity returns to a normal pressure state, and then step b is restarted; and the supporting layer of the prepared ceramic shell has a sponge-like loose structure." According to common sense, in a case that a supporting layer of a thick slurry ceramic shell is dried, rapid drying may be implemented under simpler control conditions. For instance, pressure reduction may be performed in a slower time range of 90 s, and rapid drying may be implemented by performing pumping on the sealed cavity to a vacuum state of 500 mmHg-400 mmHg. However, in fact, after research, the applicant finds it more difficult to obtain a better dried thick slurry ceramic shell under a vacuum drying condition than a thin slurry ceramic shell. For instance, in a case that a supporting layer of the thick slurry ceramic shell is dried, an environmental vacuum degree of the to-be-dried ceramic shell needs to be reduced from normal pressure to 260 mmHg-20 mmHg within 30 s and restored to normal pressure within 90 s. This is because the thick slurry ceramic shell has a low water content and a high content of sand or granular materials. Thus, flowing of water and air in the thick slurry ceramic shell is easily blocked, which leads to a problem that a surface of the ceramic shell is dry and water in the ceramic shell is not evaporated in the drying process. Thus, in a theoretically low control environment, evaporation efficiency of water in the thick slurry ceramic shell is quite different from theoretical efficiency, so it is necessary to make water and bubbles in the thick slurry ceramic shell flow effectively in a lower negative pressure environment at a higher pressure reduction speed. On one hand, a sponge-like structure uniformly distributed and caused by bubble flowing may be formed in the thick slurry ceramic shell in the drying process, and a thickness of a ceramic shell layer may be expanded. On the other hand, water in the thick slurry ceramic shell may be effectively discharged, such that rapid drying may be implemented in a real sense.

[0167] The disclosure illustratively provides a method for drying supporting layers. At least three supporting layers are sequentially arranged from a transition layer to a sealing layer.

[0168] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0169] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0170] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0171] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0172] According to the vacuum rapid drying method of the instance of the disclosure, in a vacuum drying process, the supporting layer of the thick slurry ceramic shell can have a better drying speed on one hand. On the other hand, the dried ceramic shell has a desirable breaking strength coefficient and can provide a sufficient supporting force, thus satisfying use requirements of precision casting.

[0173] The disclosure illustratively provides a vacuum rapid drying system. As shown in FIG. 1, the vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0174] The to-be-dried ceramic shell 4 is put into the vacuum drying chamber 1 for the vacuum rapid drying treatment.

[0175] The control system controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10 and the second electronic control valve 107, so as to implement method steps of the vacuum rapid drying treatment.

[0176] The vacuum rapid drying system further includes: a vacuum tank 5. One end of the vacuum tank 5 is in communication with the vacuum pump 8 through a second connecting tube. The second connecting tube is provided with a third electronic control valve 9. The other end of the vacuum tank 5 is in communication with the vacuum drying chamber 1 through a third connecting tube 7. The third connecting tube 7 is provided with a fourth electronic control valve 6.

[0177] The disclosure illustratively provides a method for pressure reduction in a case that vacuum drying is performed on supporting layers and a sealing layer. The method includes: an instantaneous pressure reduction operation. The instantaneous pressure reduction operation includes: the fourth electronic control valve 6 is firstly closed before pressure reduction, and pumping is performed on the vacuum tank 5 to a low vacuum state in advance; then, the fourth electronic control valve 6 is opened during pressure reduction, such that the vacuum drying chamber 1 is in communication with the vacuum tank 5, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally, the vacuum pump 8 simultaneously extracts gas-phase components in the vacuum tank 5 and the vacuum drying chamber 1, the fourth electronic control valve 6 and the first electronic control switching valve 10 are closed after a vacuum degree in the vacuum drying chamber 1 satisfies a preset target, and meanwhile, the vacuum pump 8 continues to extract the gas-phase components in the vacuum tank 5 until the vacuum tank 5 is in the low vacuum state.

[0178] The disclosure illustratively provides a method for vacuum rapid drying of supporting layers and a sealing layer by combining an instantaneous pressure reduction operation. At least three supporting layers are sequentially arranged from a transition layer to the sealing layer.

[0179] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 14.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 14.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.6, step 14.4 and step 14.5 are repeated until drying of the first layer of the supporting layers is completed.

[0180] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 15.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 15.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.6, step 15.4 and step 15.5 are repeated until drying of the second layer of the supporting layers is completed.

[0181] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 16.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 16.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.6, step 16.4 and step 16.5 are repeated until drying of the third layer of the supporting layers is completed.

[0182] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer includes the following steps: Step 17.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 17.2, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 120 s, and the vacuum tank 5 continues to be vacuumized. Step 17.3, step 17.1 and step 17.2 are repeated until drying of the sealing layer is completed.

[0183] The technology of the disclosure combines a specific instantaneous pressure reduction operation, such that drying time of a thick slurry shell film can be further shortened, the breaking strength coefficient can be further reduced, and an average thickness of the supporting layer of the ceramic shell can be further increased. In this way, the sufficient supporting force is kept, and meanwhile, the thick slurry ceramic shell further has an excellent breaking strength coefficient, thus improving an application field of the thick slurry ceramic shell in precision casting.

[0184] In order to explain the technical solution of the disclosure in more detail, the technology of the disclosure will be further described in detail with specific examples and comparative examples.Slurry preparation:

[0185] (1) Thick slurry A was ceramic shell slurry compounded by ceramic shell sol, powder, water and sand, and satisfied the following condition: a concentration of each layer of ceramic shell slurry was expressed by a Zahn cup method with a No.4 Zahn measuring cup, where a concentration of ceramic shell slurry of a surface layer was 58 s, a concentration of ceramic shell slurry of a transition layer was 32 s, a concentration of ceramic shell slurry of a supporting layer was 24 s, and a concentration of ceramic shell slurry of a sealing layer was 11 s. The sealing layer included no sand. Sand of 100 meshes was selected for covering a to-be-dried ceramic shell at the surface layer with sand. Sand of 60 meshes was selected for covering a to-be-dried ceramic shell at the transition layer with sand. Sand of 30 meshes was selected for covering a to-be-dried ceramic shell at the supporting layer with sand. The ceramic shell sol was silica sol, and a mass concentration of silicon dioxide was 25%. The powder was zirconium powder of 300 meshes. (2) Thin slurry was ceramic shell slurry compounded by ceramic shell sol, powder, water and sand, and satisfied the following condition: a concentration of each layer of ceramic shell slurry was expressed by a Zahn cup method with a No.4 Zahn measuring cup, where a concentration of ceramic shell slurry of a surface layer was 45 s, a concentration of ceramic shell slurry of a transition layer was 26 s, a concentration of ceramic shell slurry of a supporting layer was 14 s, and a concentration of ceramic shell slurry of a sealing layer was 11 s. The sealing layer included no sand. Sand of 100 meshes was selected for covering a to-be-dried ceramic shell at the surface layer with sand. Sand of 60 meshes was selected for covering a to-be-dried ceramic shell at the transition layer with sand. Sand of 30 meshes was selected for covering a to-be-dried ceramic shell at the supporting layer with sand. The ceramic shell sol was silica sol, and a mass concentration of silicon dioxide was 25%. The powder was zirconium powder of 300 meshes. Testing method:(1) Breaking strength coefficient:

[0186] A same batch of ceramic shells were taken and subjected to dewaxing and high temperature treatment at 1050°C for 1.5 h so as to obtain ceramic shells for casting. Thus, maximum pressure borne by the ceramic shells when the ceramic shells for casting were destroyed was used as a breaking strength coefficient. An average breaking strength coefficient of at least 5 ceramic shells in the same batch was used as the breaking strength coefficient of the example or comparative example of the disclosure.(2) Ceramic shell thickness:

[0187] A same batch of ceramic shells were taken and subjected to dewaxing and high temperature treatment at 1050°C for 1.5 h so as to obtain ceramic shells for casting. An average value of ceramic shell thicknesses at casting ports of at least 5 of the ceramic shells for casting was a ceramic shell thickness of the disclosure with a unit of cm.(3) Drying time:

[0188] An average value of drying time of each layer of a to-be-dried ceramic shell 4 from a surface layer to a sealing layer was rounded, and was the drying time of the disclosure with a unit of min. The drying time of each layer was: time consumed by putting the to-be-dried ceramic shell 4 of a corresponding layer into a vacuum rapid drying system until drying of the layer was completed.(4) Drying yield:

[0189] Q%=(a number of qualified ceramic shells dried in the batch) / (a number of all ceramic shells in the batch)*100%, which was rounded. A criterion for determining whether drying of a ceramic shell is qualified was that a dried ceramic shell was not overdried, and a humidity at a deep hole and a surface humidity of the ceramic shell were both lower than 3%.

[0190] A method 1 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry.

[0191] During the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0192] S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0193] The vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, a control system, a first data transmission module, a second data transmission module, a local database module, and a remote system module. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107. The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0194] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set and running result data.

[0195] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0196] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0197] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0198] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0199] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3. A bottom of the drying frame 3 is provided with a second air blower set 102. The drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively. An opposite side of the third air blower set 103 is provided with an adjustable member 108. The adjustable member 108 is: a sixth air blower set.

[0200] As shown in FIGs. 1-2, the drying frame 3 includes: a ceramic shell hanger 304 configured to hang the to-be-dried ceramic shell 4. The ceramic shell hanger 304 is provided with a plurality of hook recesses 305. The to-be-dried ceramic shell 4 is hooked at the hook recesses 305 through hooks 11. A hanger support 302 is fixed to a bottom of the ceramic shell hanger 304. A bottom of the hanger support 302 is provided with a plurality of rollers 303 slidable along a guide rail 301. The guide rail 301 is fixed to a bottom surface in the vacuum drying chamber 1.

[0201] The guide rail 301 is provided with a limiting block at one side away from an opening and closing door of the vacuum drying chamber 1. As shown in FIG. 1, the guide rail 301 is provided with a limiting block at one side close to an adjustable member 108.

[0202] The vacuum drying chamber 1 is internally provided with a three-dimensional detection mechanism 2. As shown in FIGs. 1-4, the three-dimensional detection mechanism 2 includes: two X-axis guide rails 201 that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber 1 and located at two sides of the drying frame 3 respectively, and a Y-axis guide rail 202 horizontally arranged along a section of the vacuum drying chamber 1. The two X-axis guide rails 201 are provided with first displacement devices 203 movable along the X-axis guide rails 201 respectively. The Y-axis guide rail 202 is fixedly arranged between the two first displacement devices 203 and is driven to move along the X-axis guide rails 201 by the two first displacement devices 203. The Y-axis guide rail 202 is provided with a second displacement device 204 movable along the Y-axis guide rail 202. The second displacement device 204 is vertically provided with an electronic control telescopic device 205 that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device 205 is fixedly provided with the scanning device 207 through an electronic control pan-tilt 206. The first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206 are connected to the control system in a signal manner separately.

[0203] As shown in FIG. 5, the electronic control pan-tilt 206 includes: a fixing platform 2061 fixed to the electronic control telescopic device 205 and a rotating platform 2062 rotatably connected to the fixing platform 2061 and rotating along a vertical axis relative to the fixing platform 2061. The rotating platform 2062 is rotatably connected to a fixed end of a second electronic control telescopic device 2064 through a reducer 2063. The reducer 2063 controls the second electronic control telescopic device 2064 to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device 2064 is fixed to the scanning device 207.

[0204] As shown in FIG. 6, the scanning device 207 includes: a photographing device 2071, a thermal imager 2072, a scanning and distance measuring device 2073, and an infrared temperature measuring device 2074. The photographing device 2071 is configured to acquire image data of the to-be-dried ceramic shell 4. The scanning and distance measuring device 2073 is configured to measure a distance of the to-be-dried ceramic shell 4 from the scanning device 207 in real time.

[0205] The control system includes: a vacuum drying control module, a fan set control module, a ceramic shell analysis module, a scanning device control module, and a drying process analysis module.

[0206] The vacuum drying control module controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10, and the second electronic control valve 107.

[0207] The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell 4 and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell 4, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell 4 and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0208] The scanning device control module is configured to control movement of the two first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206, such that the scanning device 207 photographs / scans the to-be-dried ceramic shell 4 in all directions, and image / scanning data of the to-be-dried ceramic shell 4 is obtained.

[0209] The drying process analysis module acquires a measurement quantity of the infrared temperature measuring device 2074 for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell 4 is completed.

[0210] A method for model structure analysis includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device 2073 is acquired. Step 1.2, end points of the distance measuring data set G n are connected, and a digital surface m of the surface n of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4. Step 1.6, positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell 4 and a depth H mc corresponding to each deep hole are counted, where c denotes a natural number of the deep hole in the digital surface m. Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output. Step 2.1, a scanning and distance measuring device 2073 is controlled to move to the position of the deep hole according to the position of the deep hole. Step 2.2, depth measurement data of a plurality of deep holes is acquired by adjusting orientations of the scanning and distance measuring device 2073 relative to the deep holes. Step 2.3, depth data H m-c of an original deep hole is corrected with depth measurement data having a maximum depth, and corrected data H m-c ' is obtained.

[0211] A method for acquiring the basic surface, the protruding surface and the recess surface includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0212] The drying process analysis includes the following steps: an internal temperature T of the deep hole is measured regularly or continuously; and a curve Qv of deep hole temperature T V -drying time t is made. In response to determining that a curve segment conforming to a preset curve rule appears in Qv, it is indicated that drying of the to-be-dried ceramic shell 4 is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell 4.

[0213] As shown in FIG. 9, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell 4 changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0214] In response to determining that a plurality of to-be-dried ceramic shells 4 are provided, a method for determining whether drying of the to-be-dried ceramic shells 4 is completed includes the following steps: temperatures of all the deep holes of all the to-be-dried ceramic shells 4 are measured one by one; and in response to determining that drying of more than L% of the to-be-dried ceramic shells 4 is completed, it is determined that drying of an entire batch of to-be-dried ceramic shells 4 is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells 4 of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells 4 of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells 4 of the batch d.

[0215] The fan set control analysis includes: a method A for fan set control analysis, a method B for fan set control analysis, a method C for fan set control analysis, and a method D for fan set control analysis, where the method A for fan set control analysis includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: step 3.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1; step 3.2, k S-p %=D p / D 0 *100% is computed, where k S-p % denotes control parameters of the fan sets p; and step 3.3, step 3.1 to step 3.2 are repeated until k S-p % of all the fan sets is obtained.

[0216] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p %=[1-D 0 / (D 0 +1)]*100% is computed, where k F-p % denotes control parameters of the fan sets p; and the fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p % .

[0217] The method B for fan set control analysis includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 4.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 4.2, k S-p % is acquired from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p. Step 4.3, step 4.1 to step 4.2 are repeated until k S-p % of all the fan sets is obtained.

[0218] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p % is acquired from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4, where the k F-p % denotes the control parameters of the fan sets p.

[0219] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p % .

[0220] A method for inputting k S-p % and k F-p % into the control parameter database includes: Step 5.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 5.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and the control parameters k S-p % and k F-p % in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution are determined, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 5.3, step 5.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0221] The method C for fan set control analysis includes: Step 6.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 6.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 6.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 6.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 6.5, k up-e %=(D up-e / D up )* k S-p % is computed.

[0222] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0223] The method D for fan set control analysis includes: Step 7.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 7.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 7.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 7.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 7.5, k up-e % of the corresponding fan is acquired from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0224] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0225] A method for inputting k up-e % into the control parameter database specifically includes: Step 8.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 8.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution is determined. The deep hole distribution includes: an orientation and a number of the deep holes. The optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 8.3, step 8.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D up -D up-e -k up-e % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0226] Drying of the to-be-dried ceramic shell 4 with input data in the control parameter database is performed through methods B+D for fan set control analysis. Drying of the to-be-dried ceramic shell 4 without input data in the control parameter database is performed through methods A+C for fan set control analysis.

[0227] A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: Step 9.1, the thermal imager 2072 performs real-time thermal imaging photographing on the to-be-dried ceramic shell 4 along with the scanning device 207 in a drying process of the to-be-dried ceramic shell 4, and sends an image obtained through real-time thermal imaging photographing to the control system. Step 9.2, the control system determines whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and in response to determining that there is the zone T, the following determination and operations are performed: in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T is reduced; in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T is enhanced; and in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T is enhanced.

[0228] The preset low-temperature threshold is 14°C.

[0229] The preset high-temperature threshold is 27°C.

[0230] The preset first drying time is 2 min.

[0231] The preset time threshold is 50 s.

[0232] After the to-be-dried ceramic shell is put into the vacuum rapid drying system, the vacuum rapid drying treatment is performed after standing is performed for 60 s. A method for the vacuum rapid drying treatment includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0233] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0234] At least three supporting layers are sequentially arranged from a transition layer to a sealing layer. A method for drying the supporting layers includes the following steps: An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0235] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0236] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0237] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0238] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0239] A method 2 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry. S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0240] The vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0241] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3. A bottom of the drying frame 3 is provided with a second air blower set 102. The drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively. An opposite side of the third air blower set 103 is provided with an adjustable member 108. The adjustable member 108 is: a sixth air blower set.

[0242] After the to-be-dried ceramic shell is put into the vacuum rapid drying system, the vacuum rapid drying treatment is performed after standing is performed for 60 s. A method for the vacuum rapid drying treatment includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0243] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0244] At least three supporting layers are sequentially arranged from a transition layer to a sealing layer. A method for drying the supporting layers includes the following steps: An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0245] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0246] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0247] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0248] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0249] In a case of performing the vacuum rapid drying treatment, the control system controls the fan set in the vacuum rapid drying system to run at a fixed wind direction and rated power. It is determined that drying of each layer of ceramic shell is completed after drying for preset time according to work experience or work instructions.

[0250] A method 3 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry. S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0251] S2 is performed with a rapid drying method and device for a ceramic shell of ZL201610416881.4.Example 1

[0252] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.Example 2

[0253] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.Example 3

[0254] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 3 for preparing the ceramic shell.Comparative Example 1

[0255] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thin slurry through a method 1 for preparing the ceramic shell. In order to achieve an equivalent supporting force of the ceramic shell obtained in Example 1, a number of supporting layers is 5.Comparative Example 2

[0256] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thin slurry through a method 3 for preparing the ceramic shell. In order to achieve an equivalent supporting force of the ceramic shell obtained in Example 1, a number of supporting layers is 5.Comparative Example 3

[0257] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry, and is dried at normal pressure and with 120°C hot air in a drying process.

[0258] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1-3 and Comparative Examples 1-3 are tested, and test results are shown in Table 1. Table 1 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1-3 and Comparative Examples 1-3Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 2785.450.82318-2586Example 3845.560.71240-18085Comparative Example 1705.130.96518-2595Comparative Example 2720.110.93220-12090Comparative Example 31061.090.501360 or above71%

[0259] As can be seen from the above table: (1) Through comparison between Example 1 and Example 2, it can be seen that compared with a technology of multi-directional fixed wind directions and fixed fan power, drying time of a ceramic shell of the disclosure is slightly improved by adjusting control parameters of fans in all directions during drying of the ceramic shell under the control of same control parameters such as a vacuum drying degree. However, drying time of all portions of the ceramic shell in a drying process of the ceramic shell of the disclosure is almost consistent, such that a drying yield of the ceramic shell is significantly improved. (2) Through comparison between Example 1 and Example 3, it can be seen that compared with an existing vacuum rapid drying technology, in a case that a thick slurry ceramic shell is dried, performance of the ceramic shell obtained by the disclosure is significantly improved, and a drying yield of the ceramic shell can also be significantly improved. A main reason why the drying time of Example 3 is unstable is that in the prior art, vacuum rapid drying is performed by fixing wind at two sides and rotating the ceramic shell. In a case that a deep hole faces a windward side, the drying time is relatively short. In a case that the deep hole faces a leeward side, the drying time is relatively long, and a problem of overdrying on the windward side is likely to be caused. That is, a drying yield of the ceramic shell is decreased. (3) Through comparison between Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the disclosure can promote expansion of a supporting layer of the ceramic shell to obtain the supporting layer of the ceramic shell having a greater thickness, and reduce a breaking strength coefficient of the ceramic shell. Due to less materials, a thickness of an expandable thin slurry ceramic shell is smaller than that of a thick slurry ceramic shell. Thus, in order to achieve a necessary thickness of the ceramic shell to support the ceramic shell with a sufficient supporting force, it is necessary to increase a number of supporting layers, resulting in an increase in overall drying time (a number of layers * drying time). (4) Through comparison between Example 1, Example 3 and Comparative Example 3, it can be seen that a drying yield of the thick slurry ceramic shell prepared by the disclosure is significantly improved, which is mainly due to a fact that the drying time is significantly shortened while the disclosure ensures that a drying process tends to be identical. However, the drying time is too long in a case that the thick slurry ceramic shell is dried in the prior art. Drying of the ceramic shell is a cooling process of water volatilization. That is, a temperature of the ceramic shell may drop by about 6°C during volatilization of water of the ceramic shell. In this case, the wax pattern may be cooled and shrunk due to low temperature of the ceramic shell. Because drying of the ceramic shell is also a shrinking process, the ceramic shell may shrink with shrinkage of the wax pattern. In a case that the drying time is too long, a shrinkage ratio of the wax pattern may increase, leading to a great shrinkage ratio of the ceramic shell after drying. In a case that drying is completed and the entire ceramic shell returns to a room temperature, the wax pattern may expand and lead to cracks at a joint between a surface layer of the ceramic shell and the wax pattern, thus seriously influencing a drying yield of the ceramic shell. However, due to short drying time of the disclosure, a shrinkage ratio of the wax pattern due to influence of low temperature is small. Generally, cracks may not appear at the joint between the surface layer of the ceramic shell and the wax pattern, thus improving a drying yield of the thick slurry ceramic shell. Example 4

[0260] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 6. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 4 for preparing the ceramic shell. Compared with a method 1 for preparing a ceramic shell, the method 4 for preparing a ceramic shell has the following differences: 1, A vacuum rapid drying system further includes: a vacuum tank 5. One end of the vacuum tank 5 is in communication with a vacuum pump 8 through a second connecting tube. The second connecting tube is provided with a third electronic control valve 9. The other end of the vacuum tank 5 is in communication with a vacuum drying chamber 1 through a third connecting tube 7. The third connecting tube 7 is provided with a fourth electronic control valve 6. 2, A method for vacuum rapid drying of supporting layers and a sealing layer includes: An inner surface of a first layer of the supporting layers is attached to an outer surface of a transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 14.1, an instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 14.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.4, an instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.6, step 14.4 and step 14.5 are repeated until drying of the first layer of the supporting layers is completed.

[0261] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 15.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 15.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.4, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.6, step 15.4 and step 15.5 are repeated until drying of the second layer of the supporting layers is completed.

[0262] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 16.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 16.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.4, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.6, step 16.4 and step 16.5 are repeated until drying of the third layer of the supporting layers is completed.

[0263] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer includes the following steps: Step 17.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 17.2, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 120 s, and the vacuum tank 5 continues to be vacuumized. Step 17.3, step 17.1 and step 17.2 are repeated until drying of the sealing layer is completed. The instantaneous pressure reduction operation includes: the fourth electronic control valve 6 is firstly closed before pressure reduction, and pumping is performed on the vacuum tank 5 to a low vacuum state in advance; then, the fourth electronic control valve 6 is opened during pressure reduction, such that the vacuum drying chamber 1 is in communication with the vacuum tank 5, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally, the vacuum pump 8 simultaneously extracts gas-phase components in the vacuum tank 5 and the vacuum drying chamber 1, the fourth electronic control valve 6 and the first electronic control switching valve 10 are closed after a vacuum degree in the vacuum drying chamber 1 satisfies a preset target, and meanwhile, the vacuum pump 8 continues to extract the gas-phase components in the vacuum tank 5 until the vacuum tank 5 is in the low vacuum state.

[0264] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1 and 4 are tested, and test results are shown in Table 2. Table 2 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1 and 4Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Total drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 4715.631.1338-1298

[0265] As can be seen from the above table: Through an instantaneous pressure reduction action, a breaking strength coefficient of the obtained ceramic shell can be further reduced, and a thickness of the obtained ceramic shell can be further increased. In this way, a sufficient supporting force is kept, and meanwhile, a thick slurry ceramic shell further has an excellent breaking strength coefficient, thus improving an application field of the thick slurry ceramic shell in precision casting.Example 5

[0266] As shown in FIG. 10, a structure of a ceramic shell has a conventional configuration and is provided with a holding part 402. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.Example 6

[0267] As shown in FIG. 10, a structure of a ceramic shell has a conventional configuration and is provided with a holding part 402. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.

[0268] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1-2 and 5-6 are tested, and test results are shown in Table 3. Table 3 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1-2 and 5-6Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Total drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 2785.450.82318-2586Example 5788.040.81715-2099Example 6787.970.81815-2099

[0269] As can be seen from the above table: (1) In a case that a to-be-cast member has a simple configuration, compared with a technology of fixed wind directions, the disclosure achieves similar total drying time and drying yield. (2) In a case that a to-be-cast member has a complex configuration, compared with a technology of fixed wind directions, the disclosure may achieve slightly longer total drying time and an obviously improved drying yield.

[0270] It can be seen that the method for preparing a ceramic shell of the disclosure achieves similar preparing efficiency and preparing success rate to the technology of fixed wind directions in a case that the ceramic shell having a simple configuration is prepared, and may obviously improve a technical effect in a case that the ceramic shell having a complex configuration is prepared with a breaking coefficient. Thus, the method for preparing a ceramic shell of the disclosure not only makes the obtained ceramic shell have good performance, but also is suitable for preparing ceramic shells having various configurations. The method has wide applicability, and is especially suitable for preparing ceramic shells having a complex configuration.

[0271] Although the examples of the disclosure are illustrated and described, it should be understood that those of ordinary skill in the art can make various changes, modifications, replacements and variations to the examples without departing from the principle and spirit of the disclosure, and the scope of the disclosure is limited by the appended claims and their legal equivalents.

Examples

example 1

[0252]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.

example 2

[0253]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.

example 3

[0254]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 3 for preparing the ceramic shell.

TECHNICAL FIELD

[0001] The disclosure relates to the technical field of precision casting, and particularly relates to a method for preparing and drying a ceramic shell for precision casting.BACKGROUND

[0002] Precision casting is a casting method compared with a traditional casting technology, and can obtain a relatively accurate shape and high casting accuracy. A technological process of the precision casting is as follows: firstly, a wax pattern is made, which has a consistent size and shape with a to-be-cast product; then, a ceramic shell is formed on a surface of the made wax pattern, and then, the ceramic shell is subjected to dewaxing (the wax pattern inside it is removed after melting); and finally, metal is poured into the ceramic shell subjected to dewaxing, and after the metal is cooled and solidified, the ceramic shell is broken and removed, such that an obtained casting is a required product.

[0003] In the technological process, preparing of the ceramic shell is crucial, and its quality determines quality of castings. At present, a common method for preparing a ceramic shell is: a shell molding method. Specifically, a water-soluble silica sol shell-preparing method is generally used. In this method, in a case that the ceramic shell is prepared, refractory materials are used to prepare different slurry and sand, and slurry and sand are alternately and gradually piled up on a surface of a wax pattern layer by layer, so as to manufacture the ceramic shell having a required thickness. Thus, a structure of the ceramic shell can be divided into a surface layer, a transition layer (second layer), a supporting layer (back layer), and a sealing layer. Only one surface layer, one transition layer and one sealing layer are provided, while a plurality of supporting layers are generally provided.

[0004] According to a concentration of ceramic shell slurry in a preparing process of the ceramic shell, the ceramic shells are generally divided into a thick slurry ceramic shell and a thin slurry ceramic shell. As its name implies, the thick slurry ceramic shell has a high concentration of ceramic shell slurry. Compared with the thin slurry ceramic shell, the thick slurry ceramic shell has the following main advantages: 1, Each layer of ceramic shell has a relatively great thickness, resulting in a relatively high supporting force. In this way, fewer layers of thick slurry ceramic shells can achieve a supporting force of the ceramic shell that can be achieved by more layers of thin slurry ceramic shells, and complexity of a process is reduced. 2, A surface layer of the ceramic shell has a high density, and a problem of casting penetration rarely occurs.

[0005] However, when ceramic shells are prepared in the prior art, the main reason why the thin slurry ceramic shells are still selected in most cases is that the thick slurry ceramic shells have the following insurmountable problems: 1, Due to a high concentration of slurry, sand can hardly penetrate into an entire slurry layer during sand coating, resulting in an uneven state in which coating sand is polymerized on a surface layer and an interior is void. Thus, strength of the ceramic shell is uneven, and a sand-free part is prone to cracking during drying, leading to puncture and misfire of castings. 2, Permeability of the ceramic shell is poor, and a problem of poor exhaust during casting can be caused, such that a recess surface on a casting surface caused by bubbles is likely to appear, which influences casting accuracy. 3, A breaking strength coefficient is high. Although the high breaking strength coefficient is conducive to preparing of a dense surface layer, providing a sufficient supporting force for a casting process. However, the high breaking strength coefficient of the entire ceramic shell can make it difficult to break the shell and take the casting after casting is completed. It is easy to damage the casting when the shell is broken violently, resulting in decline in casting accuracy. Thus, on the premise of ensuring that the ceramic shell has a sufficient supporting force, making the ceramic shell have a lower breaking strength coefficient has always marked a technical improvement direction in the field of precision casting. 4, Although the thick slurry ceramic shell has a low water content, water molecules have great movement resistance, so thick slurry has even longer drying time than thin slurry. In addition, in a case of involving castings having deep holes, it is difficult to make the drying time of all portions of the ceramic shell tend to be identical. Generally, after a deep hole portion of the ceramic shell is dried, the other portion of the ceramic shell may be overdried, resulting in cracking of the ceramic shell.

[0006] However, single-layer thickness expansion of the thin slurry ceramic shell is limited. In a case that a breaking strength coefficient is low, it is necessary to increase a thickness of the ceramic shell by increasing a number of layers, so as to provide a sufficient supporting force. This requires repeated slurry application, which makes the process more complex. The drying time of the ceramic shell is prolonged with an increase in the number of layers, thus significantly reducing preparing efficiency. Meanwhile, in a case of involving deep hole castings, how to make the drying time of all the portions of the thin slurry ceramic shell tend to be identical and how to complete drying in a short time are also technical problems to be solved.SUMMARY

[0007] In order to solve problems in the prior art, the disclosure provides a method for preparing a ceramic shell for precision casting. The method includes: S1, smearing an exterior of a wax pattern with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained for each corresponding layer each time after smearing of the ceramic shell slurry is completed; S2, putting the to-be-dried ceramic shell of the corresponding layer into a vacuum rapid drying system for a vacuum rapid drying treatment, and smearing, after drying of the ceramic shell of the corresponding layer is completed, same with a subsequent layer of ceramic shell slurry, where during the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical; and S3, obtaining the ceramic shell for precision casting after completion of drying of the ceramic shells at all the layers.

[0008] Further, the vacuum rapid drying system includes: a vacuum drying chamber, a vacuum pump, and a control system. The vacuum pump vacuumizes the vacuum drying chamber. The vacuum drying chamber is internally provided with a drying frame. A to-be-dried ceramic shell is arranged on the drying frame so as to be dried. The vacuum drying chamber is internally provided with at least two groups of fan sets having different wind directions around the drying frame.

[0009] The control system includes: a vacuum drying control module and a fan set control module. The vacuum drying control module vacuumizes the vacuum drying chamber and / or restores chamber pressure. The fan set control module controls starting and stopping and / or control parameters of all fan sets, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0010] Further, the vacuum drying chamber is internally provided with a first air blower set on a top of the drying frame. A bottom of the drying frame is provided with a second air blower set. The drying frame is provided with a third air blower set arranged on an opening and closing door of the vacuum drying chamber along a section of the vacuum drying chamber. The drying frame is provided with a fourth air blower set and a fifth air blower set at two sides of the vacuum drying chamber in an axial direction respectively.

[0011] Further, the vacuum drying chamber is internally provided with an adjustable member at an opposite side of the third air blower set. The adjustable member is: a condenser or a sixth air blower set.

[0012] Optionally, the vacuum drying chamber is provided with a controller assembly. The controller assembly receives and sends a control signal to the fan set control module, so as to control starting and stopping and / or the control parameters of each fan set.

[0013] Further, a controller includes: at least one of a knob controller, a key controller, a touch screen controller, and a toggle switch.

[0014] Optionally, the vacuum drying chamber is internally provided with a three-dimensional detection mechanism. The three-dimensional detection mechanism drives a scanning device to move along an X axis, a Y axis, and a Z axis.

[0015] The scanning device at least includes: a photographing device. The photographing device is configured to acquire image data of the to-be-dried ceramic shell.

[0016] The control system includes: a ceramic shell analysis module. The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0017] Further, the three-dimensional detection mechanism includes: two X-axis guide rails that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber and located at two sides of the drying frame respectively, and a Y-axis guide rail horizontally arranged along a section of the vacuum drying chamber. The two X-axis guide rails are provided with first displacement devices movable along the X-axis guide rails respectively. The Y-axis guide rail is fixedly arranged between the two first displacement devices and is driven to move along the X-axis guide rails by the two first displacement devices. The Y-axis guide rail is provided with a second displacement device movable along the Y-axis guide rail. The second displacement device is vertically provided with an electronic control telescopic device that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device is fixedly provided with the scanning device through an electronic control pan-tilt. The first displacement devices, the second displacement device, the electronic control telescopic device and the electronic control pan-tilt are connected to the control system in a signal manner separately.

[0018] Further, the control system includes: a scanning device control module. The scanning device control module is configured to control movement of the two first displacement devices, the second displacement device, the electronic control telescopic device and the electronic control pan-tilt, such that the scanning device photographs / scans the to-be-dried ceramic shell in all directions, and image / scanning data of the to-be-dried ceramic shell is obtained.

[0019] Further, the model structure analysis includes image analysis as follows: firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of the to-be-dried ceramic shell; then, comparing the acquired image data with the outer contour model data, and determining a spatial orientation of the to-be-dried ceramic shell currently hanging in the vacuum drying chamber; and finally, determining a current position and orientation of a deep hole in the to-be-dried ceramic shell according to the spatial orientation of the to-be-dried ceramic shell, and outputting the current position and orientation of the deep hole in the to-be-dried ceramic shell and depth data corresponding to the deep hole.

[0020] Further, the scanning device further includes: a scanning and distance measuring device. The scanning and distance measuring device is configured to measure a distance of the to-be-dried ceramic shell from the scanning device in real time.

[0021] The model structure analysis includes: step 1.1, scanning, by the scanning and distance measuring device, a surface n of the to-be-dried ceramic shell in all directions according to a preset line, and acquiring a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device; step 1.2, connecting end points of the distance measuring data set G n , and obtaining a digital surface m of the surface n of the to-be-dried ceramic shell; step 1.3, performing graphic analysis on the digital surface m of the to-be-dried ceramic shell by combining the image data, and determining a basic surface, a protruding surface and a recess surface of the digital surface m; step 1.4, computing a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk; step 1.5, using C mk-b >K 2 as a deep hole and C mk-b >K 3 as a through hole, where K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell; step 1.6, counting positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell and a depth H mc corresponding to each deep hole, where c denotes a natural number of the deep hole in the digital surface m; step 1.7, repeating step 1.1 to step 1.6 until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell are counted, and determining an orientation X mc of the deep hole according to the surface n where the deep hole is located; and step 1.8, outputting data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell.

[0022] Further, in step 1.3, a method for acquiring the basic surface, the protruding surface and the recess surface includes: step 1.3.1, acquiring the image data corresponding to the digital surface m of the to-be-dried ceramic shell, and splicing the image data so as to obtain an image surface R; step 1.3.2, performing element identification on the image surface R, and obtaining an element zone rn-m on the image surface R, where rn denotes a sequence number of the element zone in the digital surface m; step 1.3.3, adjusting the digital surface m to have a same orientation and a similar size to the image surface R; step 1.3.4, using an element zone rc-m having a maximum continuous area as the basic surface, where the rc-m belongs to rn-m; step 1.3.5, acquiring distance measuring point data of an element zone of each non-basic surface, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point; and step 1.3.6, using the element zone as a boundary, and connecting adjacent recess point and protruding point to form the recess surface and the protruding surface.

[0023] Further, the three-dimensional detection mechanism is provided with an electronic control telescopic device. A tail end of a telescopic end of the electronic control telescopic device is fixedly provided with a scanning device through an electronic control pan-tilt.

[0024] Optionally, the electronic control pan-tilt includes: a fixing platform fixed to the electronic control telescopic device and a rotating platform rotatably connected to the fixing platform and rotating along a vertical axis relative to the fixing platform. The rotating platform is rotatably connected to a fixed end of a second electronic control telescopic device through a reducer. The reducer controls the second electronic control telescopic device to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device is fixed to the scanning device.

[0025] Further, the model structure analysis further includes: step 2.1, controlling a scanning and distance measuring device to move to the position of the deep hole according to the position of the deep hole; step 2.2, acquiring depth measurement data of a plurality of deep holes by adjusting orientations of the scanning and distance measuring device relative to the deep holes; and step 2.3, correcting depth data H m-c of an original deep hole with depth measurement data having a maximum depth, and obtaining corrected data H m-c '.

[0026] Further, the scanning device further includes: an infrared temperature measuring device. The control system includes: a drying process analysis module that acquires a measurement quantity of the infrared temperature measuring device for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell is completed.

[0027] The drying process analysis includes: measuring an internal temperature T of the deep hole regularly or continuously; and making a curve Q v of deep hole temperature T v -drying time t. In response to determining that a curve segment conforming to a preset curve rule appears in Q v , it is indicated that drying of the to-be-dried ceramic shell is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell.

[0028] Further, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0029] Further, in response to determining that a plurality of to-be-dried ceramic shells of a same batch are provided, temperatures of all the deep holes of all the to-be-dried ceramic shells are measured one by one. In response to determining that drying of more than L% of the to-be-dried ceramic shells is completed, it is determined that drying of the entire batch of to-be-dried ceramic shells is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells of the batch d.

[0030] Further, the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells having deep holes in surfaces, the following method is used: step 3.1, acquiring a total number D 0 of all the deep holes of the to-be-dried ceramic shells, and acquiring a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells faced by the fan sets p, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber; step 3.2, computing k S-p% =D p / D 0 *100%, where k S-p % denotes control parameters of the fan sets p; and step 3.3, repeating step 3.1 to step 3.2 until k S-p % of all the fan sets is obtained.

[0031] In a case that all fan sets p face the to-be-dried ceramic shells having no deep holes in surfaces, the following method is used: computing k F - p %=[1-D 0 / (D 0 +1)]*100%, where K F-p % denotes control parameters of the fan sets p; and sending, by the fan set control module, obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0032] Further, the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells having deep holes in surfaces, the following method is used: step 4.1, acquiring a total number D 0 of all the deep holes of the to-be-dried ceramic shells, and acquiring a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells faced by the fan sets p, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber; step 4.2, acquiring k S-p % from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p; and step 4.3, repeating step 4.1 to step 4.2 until k S-p % of all the fan sets is obtained.

[0033] In a case that all fan sets p face the to-be-dried ceramic shells having no deep holes in surfaces, the following method is used: acquiring k F-p % from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells, where the k F-p % denotes the control parameters of the fan sets p; and sending, by the fan set control module, obtained k S-p % and k F-p %of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0034] Further, a method for inputting k S-p % and k F-p% into the control parameter database includes: step 5.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber 1 in a simulation apparatus; step 5.2, presetting a deep hole distribution of different to-be-dried ceramic shells for drying training, and determining the control parameters k S-p % and k F-p %in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4; and step 5.3, repeating step 5.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p %, and storing the deep hole-control parameter relation set in the control parameter database.

[0035] Further, at least two fans are arranged and mounted in the fan set. The fan set control module synchronously or independently controls the fans in each fan set.

[0036] Further, the fan set control analysis further includes: step 6.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device; step 6.2, recording, by the scanning device, a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell in a model structure analysis process; step 6.3, acquiring a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p, where e denotes a natural number of the fans in the fan set p; step 6.4, counting a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p; and step 6.5, computing k up-e %=(D up-e / D up )*k S-p %.

[0037] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0038] Further, the fan set control analysis includes: step 7.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device; step 7.2, recording, by the scanning device, a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell in a model structure analysis process; step 7.3, acquiring a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p, where e denotes a natural number of the fans in the fan set p; step 7.4, counting a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p; and step 7.5, acquiring k up-e % of the corresponding fan from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0039] The fan set control module sends obtained k up-e% of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0040] Further, a method for acquiring the k up-e % includes: step 8.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber in a simulation apparatus; step 8.2, presetting a deep hole distribution of different to-be-dried ceramic shells for drying training, and determining a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells; and step 8.3, repeating step 8.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of D up -D up-e -k up-e %, and storing the deep hole-control parameter relation set in the control parameter database.

[0041] Further, the vacuum rapid drying system includes: a first data transmission module, a local database module, and a remote system module.

[0042] The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0043] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set.

[0044] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0045] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0046] Further, the vacuum rapid drying system includes a second data transmission module.

[0047] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0048] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0049] Further, the scanning device includes: a thermal imager. A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: step 9.1, performing, by the thermal imager, real-time thermal imaging photographing on the to-be-dried ceramic shell along with the scanning device in a drying process of the to-be-dried ceramic shell, and sending an image obtained through real-time thermal imaging photographing to the control system; and step 9.2, determining, by the control system, whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and performing, in response to determining that there is the zone T, the following determination and operations: reducing, in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T; enhancing, in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T; and enhancing, in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T.

[0050] Further, the preset low-temperature threshold is 12°C-15°C. The preset high-temperature threshold is 26°C-28°C. The preset first drying time is 1 min-3 min. The preset time threshold is 30 s-60 s.

[0051] Further, a method for the vacuum rapid drying treatment includes: in a case that a surface layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 750 mmHg-720 mmHg within 5 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 750 mmHg-720 mmHg to the normal pressure within 5 s; and circulating the above process until drying of the surface layer is completed; in a case that a transition layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 720 mmHg-680 mmHg within 7 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 720 mmHg-680 mmHg to the normal pressure within 7 s; and circulating the above process until drying of the transition layer is completed; in a case that a supporting layer is dried, the method comprises the following steps: step 10.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 10.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 10.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 10.6, repeating step 10.4 and step 10.5 until drying of the supporting layer is completed; and in a case that a sealing layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 120 mmHg-90 mmHg within 40 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell to the normal pressure within 120 s; and circulating the above process until drying of the sealing layer is completed.

[0052] Further, at least three supporting layers are sequentially arranged from the transition layer to the sealing layer.

[0053] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers is used and includes the following steps: step 11.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 11.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; step 11.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and step 11.6, repeating step 11.4 and step 11.5 until drying of the first layer of the supporting layers is completed.

[0054] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers is used and includes the following steps: step 12.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 12.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; step 12.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and step 12.6, repeating step 12.4 and step 12.5 until drying of the second layer of the supporting layers is completed.

[0055] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers is used and includes the following steps: step 13.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 13.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 13.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 13.6, repeating step 13.4 and step 13.5 until drying of the third layer of the supporting layers is completed.

[0056] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0057] Further, the vacuum rapid drying system includes: a vacuum drying chamber, a vacuum pump, and a control system. The vacuum pump vacuumizes the vacuum drying chamber. The vacuum pump is in communication with the vacuum drying chamber through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve. The vacuum drying chamber is in communication with an air tube. The air tube is provided with a second electronic control valve.

[0058] The to-be-dried ceramic shell is put into the vacuum drying chamber for the vacuum rapid drying treatment.

[0059] The control system controls opening and closing of the vacuum pump, the first electronic control switching valve and the second electronic control valve, so as to implement method steps of the vacuum rapid drying treatment.

[0060] Further, the vacuum rapid drying system further includes: a vacuum tank. One end of the vacuum tank is in communication with the vacuum pump through a second connecting tube. The second connecting tube is provided with a third electronic control valve. The other end of the vacuum tank is in communication with the vacuum drying chamber through a third connecting tube. The third connecting tube is provided with a fourth electronic control valve. Further, a method for performing vacuum drying on the supporting layers and the sealing layer further includes an instantaneous pressure reduction operation. The instantaneous pressure reduction operation includes: firstly closing the fourth electronic control valve before pressure reduction, and performing pumping on the vacuum tank to a low vacuum state in advance; then opening the fourth electronic control valve during pressure reduction, such that the vacuum drying chamber is in communication with the vacuum tank, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally simultaneously extracting, by the vacuum pump, gas-phase components in the vacuum tank and the vacuum drying chamber, closing the fourth electronic control valve and the first electronic control switching valve after a vacuum degree in the vacuum drying chamber satisfies a preset target, and meanwhile, continuing to extract, by the vacuum pump, the gas-phase components in the vacuum tank until the vacuum tank is in the low vacuum state.

[0061] Further, on the basis that the method for performing vacuum drying on the supporting layers and the sealing layer further includes the instantaneous pressure reduction operation: a method for performing a vacuum rapid drying treatment of a first layer of the supporting layers is used and includes the following steps: step 14.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank vacuumized; step 14.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 14.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and making the vacuum tank continue to be vacuumized; step 14.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank vacuumized; step 14.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and making the vacuum tank continue to be vacuumized; and step 14.6, repeating step 14.4 and step 14.5 until drying of the first layer of the supporting layers is completed.

[0062] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: step 15.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank vacuumized; step 15.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 15.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and making the vacuum tank continue to be vacuumized; step 15.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank vacuumized; step 15.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and making the vacuum tank continue to be vacuumized; and step 15.6, repeating step 15.4 and step 15.5 until drying of the second layer of the supporting layers is completed.

[0063] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers is used and includes the following steps: step 16.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank vacuumized; step 16.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank continue to be vacuumized; step 16.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and making the vacuum tank continue to be vacuumized; step 16.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank vacuumized; step 16.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and making the vacuum tank continue to be vacuumized; and step 16.6, repeating step 16.4 and step 16.5 until drying of the third layer of the supporting layers is completed.

[0064] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer is used and includes the following steps: step 17.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, keeping the vacuum tank vacuumized; step 17.2, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 120 s; and making the vacuum tank continue to be vacuumized; and step 17.3, repeating step 17.1 and step 17.2 until drying of the sealing layer is completed.

[0065] The disclosure at least has one of the following beneficial effects: 1, On the basis of retaining inherent advantages of a thick slurry ceramic shell, the disclosure effectively solves problems present of the thick slurry ceramic shell, and provides a thick slurry ceramic shell excellent in average layer thickness, high in air permeability, uniform in sand coverage and excellent in breaking strength coefficient. 2, The disclosure can make the drying time of all the portions of the ceramic shell tend to be identical through manual control or automatic analysis control, and especially in a case involving a deep hole structure having great uniform difficulty in drying, the drying time of the deep holes and the surface can be effectively balanced, and an optimal result is obtained. 3, The disclosure has abilities of remote control and remote sharing, and can synchronize an optimal fan control method to all vacuum drying systems, thus significantly reducing trial and error cost when enterprises dry various types of ceramic shells and improving enterprise benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a schematic structural diagram of a vacuum rapid drying system of the disclosure; FIG. 2 shows a schematic diagram of an internal structure of a vacuum drying chamber of the disclosure; FIG. 3 shows a schematic diagram of a local structure of a three-dimensional detection mechanism of the disclosure; FIG. 4 shows a schematic diagram of a local structure of a Z axis of a three-dimensional detection mechanism of the disclosure; FIG. 5 shows a schematic structural diagram of an electronic control pan-tilt of the disclosure; FIG. 6 shows a schematic structural diagram of a scanning device of the disclosure; FIG. 7 shows a schematic structural diagram of an illustrative ceramic shell; FIG. 8 shows a schematic diagram of scanning the ceramic shell shown in FIG. 7 with a scanning device of the disclosure; FIG. 9 shows a schematic diagram of a temperature-time curve of a preset curve rule for determining whether drying is completed of the disclosure; and FIG. 10 shows a schematic structural diagram of another illustrative ceramic shell.

[0067] In the figures: 1, vacuum drying chamber; 101, first air blower set; 102, second air blower set; 103, third air blower set; 104, fourth air blower set; 105, fifth air blower set; 106, air tube; 107, second electronic control valve; 108, adjustable member; 2, three-dimensional detection mechanism; 201, X-axis guide rail; 202, Y-axis guide rail; 203, first displacement device; 204, second displacement device; 205, electronic control telescopic device; 206, electronic control pan-tilt; 2061, fixing platform; 2062, rotating platform; 2063, reducer; 2064, second electronic control telescopic device; 207, scanning device; 2071, photographing device; 2072, thermal imager; 2073, scanning and distance measuring device; 2074, infrared temperature measuring device; 3, drying frame; 301, guide rail; 302, hanger support; 303, roller; 304, ceramic shell hanger; 305, hook recess; 4, to-be-dried ceramic shell; 401, deep hole; 402, holding part; 5, vacuum tank; 6, fourth electronic control valve; 7, third connecting tube; 8, vacuum pump; 9, third electronic control valve; 10, first electronic control switching valve; and 11, hook.DETAILED DESCRIPTION OF EMBODIMENTS

[0068] The disclosure is described in further detail below with reference to the accompanying drawings. It should be noted that the description is merely illustrative, and is not intended to limit the scope of the disclosure. Further, description of well-known structures and technologies is omitted in the following description, such that concepts of the disclosure are prevented from being unnecessarily confused.

[0069] The disclosure illustratively provides a method for preparing a ceramic shell for precision casting. The method includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry.

[0070] During the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0071] S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0072] The disclosure makes the drying time of all the portions of the to-be-dried ceramic shell tend to be identical by adjusting the control parameters of each air blower in different side directions of the to-be-dried ceramic shell. Especially, in a case involving a deep hole structure having great uniform difficulty in drying, the drying time of the deep holes and the surface can be effectively balanced.

[0073] The disclosure illustratively provides a vacuum rapid drying system. As shown in FIG. 1, the vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0074] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with at least two groups of fan sets having different wind directions around the drying frame 3.

[0075] The control system includes: a vacuum drying control module and a fan set control module. The vacuum drying control module controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10, and the second electronic control valve 107. The fan set control module controls starting and stopping and / or the control parameters of all the fan sets.

[0076] In the vacuum drying system of the prior art, the added fan set generally uses a constant-speed running method. In order to achieve uniformity of drying, in the prior art, as shown in the prior patent technology of the applicant: CN201610416881.4, two groups of fan sets and ceramic shell rotating devices in different directions are used to make the ceramic shell continuously rotate so as to be exposed to wind in a drying process, such that balance of the drying process is improved. However, the method has the following problems: 1, In a case that a complex component having deep holes is dried, a problem that drying time of the deep holes is relatively consistent with drying time of other portions cannot be solved. That is, in a case that a complex component having deep holes is dried, the other portions of the ceramic shell may still be overdried when drying of deep hole portions of the ceramic shell is completed. 2, The ceramic shell has a certain centrifugal force in a rotation process, such that sand in the ceramic shell is likely to deviate centrifugally, especially when viscosity of slurry is low. 3, The ceramic shell needs to be rotated continuously in the drying process, which leads to a possibility of relative sliding of the to-be-dried ceramic shell, and further a possibility of colliding of the ceramic shell or slipping of a rotary disc, resulting in damage of the ceramic shell.

[0077] By means of the vacuum drying system of the disclosure, the fan set in the vacuum drying chamber 1 may be controlled accordingly through the fan set control module, such that drying degrees of all the portions of the ceramic shell may be changed by providing winds different in side directions and intensities. A windward surface of the ceramic shell having the deep hole structure has a strong wind force, which is conducive to rapid volatilization of water in the deep holes. In addition, a windward surface of the ceramic shell having no deep hole structure has a weak wind force, which prevents the portion of the ceramic shell from being dried too rapidly, such that the drying time of all the portions of the ceramic shell tends to be identical.

[0078] The disclosure illustratively provides composition of a fan set. Specifically, as shown in FIGs. 1 and 3, the vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3, a bottom of the drying frame 3 is provided with a second air blower set 102, the drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively.

[0079] The disclosure illustratively provides an additional member. As shown in FIG. 1, the vacuum drying chamber 1 is internally provided with an adjustable member 108 at an opposite side of the third air blower set 103. The adjustable member 108 is: a condenser or a sixth air blower set.

[0080] The disclosure illustratively provides a method for controlling a fan set. Specifically, the vacuum drying chamber 1 is provided with a controller assembly. The controller assembly receives and sends a control signal to the fan set control module, so as to control starting and stopping and / or the control parameters of each fan set.

[0081] The disclosure illustratively provides a controller. The controller includes: at least one of a knob controller, a key controller, a touch screen controller, and a toggle switch.

[0082] In this way, a running state of the fan sets may be controlled through off-line control. That is, the controller may select whether all the fan sets are started and a running ratio at which the fan sets run. The running ratio is a ratio of a current fan speed to a rated speed.

[0083] The method makes an overall structure of the control system relatively simple. However, in a case that the ceramic shell is dried, an operator needs to observe a direction of the deep holes of the to-be-dried ceramic shell, and control the running ratio of each corresponding fan set according to experience. A drying effect is highly correlated with an observation ability and work experience of the staff.

[0084] The disclosure illustratively provides a method for controlling a fan set. Specifically, as shown in FIGs. 1-2, the vacuum drying chamber 1 is internally provided with a three-dimensional detection mechanism 2. The three-dimensional detection mechanism 2 drives a scanning device 207 to move along an X axis, a Y axis, and a Z axis.

[0085] As shown in FIG. 6, the scanning device 207 includes: a photographing device 2071. The photographing device 2071 is configured to acquire image data of the to-be-dried ceramic shell 4.

[0086] The control system includes: a ceramic shell analysis module. The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell 4 and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell 4, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell 4 and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0087] The image data is analyzed to rapidly determine a basic structure of the ceramic shell, and whether there are deep holes and positions and orientations of the deep holes is determined, such that the fan sets facing the deep holes can be determined and controlled at a corresponding fan running ratio.

[0088] The disclosure illustratively provides a three-dimensional detection mechanism. As shown in FIGs. 1-4, the three-dimensional detection mechanism 2 includes: two X-axis guide rails 201 that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber 1 and located at two sides of the drying frame 3 respectively, and a Y-axis guide rail 202 horizontally arranged along a section of the vacuum drying chamber 1. The two X-axis guide rails 201 are provided with first displacement devices 203 movable along the X-axis guide rails 201 respectively. The Y-axis guide rail 202 is fixedly arranged between the two first displacement devices 203 and is driven to move along the X-axis guide rails 201 by the two first displacement devices 203. The Y-axis guide rail 202 is provided with a second displacement device 204 movable along the Y-axis guide rail 202. The second displacement device 204 is vertically provided with an electronic control telescopic device 205 that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device 205 is fixedly provided with the scanning device 207 through an electronic control pan-tilt 206. The first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206 are connected to the control system in a signal manner separately.

[0089] The disclosure illustratively provides a control system. The control system includes: a scanning device control module. The scanning device control module is configured to control movement of the two first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206, such that the scanning device 207 photographs / scans the to-be-dried ceramic shell 4 in all directions, and image / scanning data of the to-be-dried ceramic shell 4 is obtained.

[0090] The scanning device control module may control the three-dimensional detection mechanism of the disclosure to drive the scanning device 207 to move in three dimensions of an X axis, a Y axis and a Z axis, such that 5 surfaces of a front surface, a rear surface, a left surface, a right surface and a top surface of the to-be-dried ceramic shell 4 are scanned in all directions, and a bottom of the to-be-dried ceramic shell is scanned laterally. Thus, an image of a main structure of the to-be-dried ceramic shell 4 is obtained, such that the positions and the orientations of the deep holes of the to-be-dried ceramic shell 4 can be determined more accurately.

[0091] The disclosure illustratively provides a method for model structure analysis. The method specifically includes image analysis: firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of the to-be-dried ceramic shell 4; then, comparing the acquired image data with the outer contour model data, and determining a spatial orientation of the to-be-dried ceramic shell 4 currently hanging in the vacuum drying chamber 1; and finally, determining a current position and orientation of a deep hole in the to-be-dried ceramic shell 4 according to the spatial orientation of the to-be-dried ceramic shell 4, and outputting the current position and orientation of the deep hole in the to-be-dried ceramic shell 4 and depth data corresponding to the deep hole.

[0092] With rapid development of digital technologies in recent years, it is possible to design the to-be-dried ceramic shell through digital modeling, and the to-be-dried ceramic shell designed through digital modeling has detailed structural data. Thus, the disclosure compares the image data of the to-be-dried ceramic shell with a digital model in an actual environment, such that the positions and the orientations of the deep holes of the ceramic shell are rapidly determined through the image data of the to-be-dried ceramic shell. Then, a depth of the corresponding deep hole is acquired from the digital model, such that the positions and the orientations of the deep holes of the to-be-dried ceramic shell 4 and the depth data corresponding to the deep holes can be obtained.

[0093] The disclosure illustratively provides a scanning device 207. As shown in FIG. 6, the scanning device 207 further includes: a scanning and distance measuring device 2073. The scanning and distance measuring device 2073 is configured to measure a distance of the to-be-dried ceramic shell 4 from the scanning device 207 in real time.

[0094] The disclosure illustratively provides a method for model structure analysis. The method includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device 2073 is acquired. Step 1.2, end points of the distance measuring data set G n are connected, and a digital surface m of the surface n of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4; Step 1.6, positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell 4 and a depth H mc corresponding to each deep hole are counted, where c denotes a natural number of the deep hole in the digital surface m. Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output.

[0095] The disclosure illustratively provides a method for acquiring the basic surface, the protruding surface and the recess surface in step 1.3. The method includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0096] FIG. 7 shows a to-be-dried ceramic shell 4 including a deep hole 401. With a left front view with n=1 of six front views of the to-be-dried ceramic shell 4 as an instance, the method specifically includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n=1 of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G1 of all scanning points on the surface n=1 from the scanning and distance measuring device 2073 is acquired. Step 1.2, as shown in FIG. 8, end points of the distance measuring data set G1 are connected, and a digital surface m=1 of the surface n=1 of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m=1 of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m=1 are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Two recesses k=1 and k=2 are provided on the digital surface m=1, where internal distance measuring points of k=1 include 5 distance measuring points of b=8 to b=12. Thus, C mk-b =C 11-8 =|(L 11-8 )-(L 11-13 )|, C mk-b =C 11-9 =< |(L 11-9 )-(L 11-13 )|, C mk-b =C 11-10 =< |(L 11-10 )-(L 11-13 )|, C mk-b =< C 11-11 =(L 11-11 )-(L 11-13 )|, and C mk-b =< C 11-12 =|(L 11-12 )-( 11-13 )| need to be computed. Internal distance measuring points of k=2 include 4 distance measuring points of b=18 to b=21. Thus, C mk-b =C 11-18 =|(L 11-18 )-(L 11-13 )|, C mk-b =C 11-19 =| (L 11-19 )-(L 11-13 )|, C mk-b =C 11-20 =|(L 11-20 )-(L 11-13 )|, and C mk-b =C 11-21 =|(L 11-21 )-(L 11-13 )| need to be computed. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4. For instance, C mk-b =C 11-10 > K 2 . Thus, a recess with k=1 on the digital surface m=1 is a deep hole. Step 1.6, positions W mc =W 11 of all deep holes in the digital surface m=1 of the to-be-dried ceramic shell 4 and a depth H mc =H 11 corresponding to each deep hole are counted, where c=1 denotes a natural number of the deep hole in the digital surface m=1. The positions of W mc =W 11 are positions corresponding to distance measuring points 8 to 12, and the depth H mc =H 11 corresponding to the deep hole is a computed value of C mk-b =C 11-10 . Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output.

[0097] The disclosure illustratively provides a method for acquiring the basic surface, the protruding surface and the recess surface in step 1.3. The method includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0098] In the prior art, not all the to-be-dried ceramic shells 4 are obtained through digital model designing, or a digital model of the to-be-dried ceramic shell 4 obtained through digital model designing is not supported by the vacuum rapid drying system. In this case, the vacuum rapid drying system fails to determine whether a shadow in the image data is a deep hole through the digital model, and fails to determine the depth of the deep hole through the image data. Through the method of the disclosure, through automatic scanning and analysis, data of the positions W mc , the depths H mc and the orientations X mc of all the deep holes in the surface of the to-be-dried ceramic shell 4 may be determined through automatic analysis. In this way, the vacuum rapid drying system may acquire necessary data of the positions W mc , the depths H mc and the orientations X mc of all the deep holes in the surface of the to-be-dried ceramic shell 4, so as to perform fan set control analysis.

[0099] The disclosure illustratively provides an electronic control pan-tilt 206. As shown in FIG. 5, the electronic control pan-tilt includes: a fixing platform 2061 fixed to the electronic control telescopic device 205 and a rotating platform 2062 rotatably connected to the fixing platform 2061 and rotating along a vertical axis relative to the fixing platform 2061. The rotating platform 2062 is rotatably connected to a fixed end of a second electronic control telescopic device 2064 through a reducer 2063. The reducer 2063 controls the second electronic control telescopic device 2064 to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device 2064 is fixed to the scanning device 207.

[0100] It is difficult to scan the bottom of the to-be-dried ceramic shell 4 with a conventional pan-tilt, such that the disclosure improves a pan-tilt structure. On one hand, the scanning device 207 may scan the bottom of the to-be-dried ceramic shell 4 through the second electronic control telescopic device 2064. On the other hand, a rotating orientation of the scanning device 207 may be changed through the reducer 2063, which increases a freedom degree of scanning movement. Thus, the scanning device 207 may adapt to scanning of a more complex to-be-dried ceramic shell 4.

[0101] The disclosure illustratively provides a method for model structure analysis. Based on the model structure analysis, the method further includes: Step 2.1, a scanning and distance measuring device 2073 is controlled to move to the position of the deep hole according to the position of the deep hole. Step 2.2, depth measurement data of a plurality of deep holes is acquired by adjusting orientations of the scanning and distance measuring device 2073 relative to the deep holes. Step 2.3, depth data H m-c of an original deep hole is corrected with depth measurement data having a maximum depth, and corrected data H m-c ' is obtained.

[0102] In a case that the to-be-dried ceramic shell 4 is designed, the deep hole structure is generally designed on an axis of a model, such that the deep holes of the ceramic shell are distributed along the axis. In this way, in a scanning and distance measuring process, distance measuring laser may penetrate into the deep holes, and distance measuring data of the deep holes may be measured. Thus, the depths of the deep holes may be obtained. However, in actual work, not all the deep holes of the ceramic shell are designed along the axis, and not all the to-be-dried ceramic shells 4 are placed forward or hooked during drying. Thus, an orientation of the deep hole may deflect relative to a running axis of the scanning device 207. In this case, laser emitted by the scanning and distance measuring device 2073 cannot penetrate into the deep hole, and a measured depth of the deep hole may be wrong. In this way, accuracy of fan set control analysis is influenced, and an actual drying speed of the deep hole portion of the to-be-dried ceramic shell 4 is quite different from a designed drying speed, thus influencing drying uniformity of all the portions of the to-be-dried ceramic shell 4.

[0103] Through a supplementary method for model structure analysis of the disclosure, the scanning and distance measuring device 2073 may obtain a plurality of distance measuring data having different orientations relative to the deep holes by adjusting the orientations of the scanning and distance measuring device 2073 relative to the deep holes at the positions of the deep holes. The distance measuring data includes distance measuring point data in which the orientation of the scanning and distance measuring device 2073 is consistent with or similar to that of an axis of the deep holes. The distance measuring data is consistent with or similar to the depth of the deep hole. Thus, accuracy of the fan set control analysis can be significantly improved. In this way, a difference between the actual drying speed and the designed drying speed of the deep hole portion of the to-be-dried ceramic shell 4 is significantly reduced.

[0104] The disclosure illustratively provides a scanning device 207. As shown in FIG. 6, based on the scanning device 207, an infrared temperature measuring device 2074 is further included. The control system includes: a drying process analysis module. The drying process analysis module acquires a measurement quantity of the infrared temperature measuring device 2074 for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell 4 is completed.

[0105] The disclosure illustratively provides a method for drying process analysis. The method includes the following steps: an internal temperature T of the deep hole is measured regularly or continuously; and a curve Q v of deep hole temperature T V -drying time t is made. In response to determining that a curve segment conforming to a preset curve rule appears in Q v , it is indicated that drying of the to-be-dried ceramic shell 4 is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell 4.

[0106] The disclosure illustratively provides a preset curve rule. As shown in FIG. 9, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell 4 changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0107] In the prior art, a method for determining whether drying of the to-be-dried ceramic shell 4 is completed mainly depends on experience or several tests, such that the corresponding drying time is obtained under certain drying conditions. In response to determining that the drying time is reached, it is determined that drying is completed. However, in a case that the method is used for the to-be-dried ceramic shells 4 changing in a plurality of batches, since the to-be-dried ceramic shells 4 in all the batches have inconsistent structures, their drying time needs to be adjusted accordingly. Thus, it is necessary to test the drying time in advance, which seriously influences overall drying efficiency.

[0108] After research, the applicant finds that in the drying process of the to-be-dried ceramic shell 4, water volatilization is an endothermic process, and at an initial stage of drying, ceramic shell slurry has a high water content. Thus, a large amount of water may be volatilized at the initial stage of drying of the ceramic shell, resulting in a significant drop in temperature of the ceramic shell. After water is volatilized to a certain extent, the water content of the ceramic shell slurry decreases, and accordingly, a volatilization speed of water decreases. Thus, a temperature of the ceramic shell may gradually tend to be a drying environment temperature. When the temperature of the ceramic shell is kept at the drying environment temperature, it is indicated that almost no water is volatilized, which indicates that drying is completed. Thus, a method for determining whether drying of the to-be-dried ceramic shell 4 is completed of the disclosure is used to determine whether drying of the to-be-dried ceramic shell 4 is completed, which is only related to a temperature change curve in the drying process, and not related to a structure of the to-be-dried ceramic shell 4. In this way, each batch of to-be-dried ceramic shells 4 may be accurately dried, which effectively solves problems existing in an existing drying time control method.

[0109] Meanwhile, after research, the applicant finds that, on one hand, temperature of the ceramic shell slurry decreases with volatilization of water in the drying process, and on the other hand, water volatilization may lead to certain shrinkage of the ceramic shell (even if the ceramic shell is supported by sand). In this case, at the initial stage of drying the ceramic shell, the wax pattern may be cooled and shrink due to cooling of the ceramic shell. Thus, the ceramic shell may adhere to a surface of a shrunk wax pattern in the drying process. In a case that a temperature of the ceramic shell starts to rise, the wax pattern may expand with a temperature rise. However, a shrinkage and expansion process of the wax pattern influenced by temperature is slower than that of the ceramic shell.

[0110] If cooling time of the ceramic shell is too long, that is, a cooling range is small and drying time is too long, the wax pattern may completely shrink at a low temperature for a long time. On one hand, the ceramic shell may adhere to an obviously shrunk wax pattern, leading to obvious spatial deformation of castings of a final ceramic shell and influencing casting accuracy. On the other hand, in a case that a temperature of the wax pattern rises and the wax pattern expands, due to too great a shrinkage-expansion ratio, it is easy to break the ceramic shell solidified and attached to a surface of the shrunk wax pattern. This situation leads to failure of ceramic shell preparing or irregular spikes on a casting surface, influencing casting accuracy. Moreover, too long drying time further influences preparing efficiency of the ceramic shell.

[0111] If cooling time of the ceramic shell is too short, that is, a cooling range is too great and drying time is too short, a problem that a deep hole is not dried completely and a surface is overdried often occurs, that is, an empty window period for adjusting the drying time is very short, which is not conducive to adjustment of the drying time of all the portions of the to-be-dried ceramic shell 4. This situation increases difficulty of controlling drying uniformity of the to-be-dried ceramic shell 4.

[0112] Due to a low concentration of the ceramic shell slurry and a high water content of a thin slurry ceramic shell, less slurry may be applied during slurry application. Thus, a thickness of each layer of ceramic shell is small, and thermal conductivity is high. This situation leads to various unfavorable problems caused by too long or too short cooling time of the thin slurry ceramic shell, so control accuracy of the drying process is too high, which is difficult to implement.

[0113] However, compared with the thin slurry ceramic shell, a thick slurry ceramic shell has a higher concentration of the ceramic shell slurry and a lower water content, so more slurry may be applied during slurry application. Thus, each layer of ceramic shell is great in thickness and poor in thermal conductivity. Under a condition that a T 2 temperature defined by the disclosure is 5°C-7°C lower than a T 1 temperature, the ceramic shell may have a suitable drying speed. On one hand, the situation that all the portions of the ceramic shell are dried too rapidly such that drying progress is not easy to adjust may be avoided while efficient drying is performed. On the other hand, drying may be completed in a case that the wax pattern is not completely shrunk, and then both the wax pattern and the ceramic shell are returned to a room temperature. Thus, a problem that the wax pattern expands and cracks the ceramic shell can be avoided.

[0114] The disclosure illustratively provides a method for determining whether drying of a plurality of to-be-dried ceramic shells 4 is completed. The method includes the following steps: temperatures of all the deep holes of all the to-be-dried ceramic shells 4 are measured one by one; and in response to determining that drying of more than L% of the to-be-dried ceramic shells 4 is completed, it is determined that drying of an entire batch of to-be-dried ceramic shells 4 is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells 4 of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells 4 of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells 4 of the batch d.

[0115] In order to improve drying efficiency of ceramic shells, a plurality of to-be-dried ceramic shells 4 having a same structure are generally dried synchronously in a batch of drying process. Due to different placement or hooking methods of the plurality of to-be-dried ceramic shells 4, a degree of wind exposure of each of the to-be-dried ceramic shells 4 is different, and the drying time is varied. Thus, it is necessary to control a certain margin, and vacuum rapid drying is stopped after drying of most of the to-be-dried ceramic shells 4 is completed, such that a problem of excessive drying of most of the to-be-dried ceramic shells 4 after drying of the ceramic shells exposed to less wind is completed is avoided. The preset percentage threshold is determined according to wind difference of the to-be-dried ceramic shells 4, and is generally not smaller than 98%. In this way, after drying is completed, even if a to-be-dried ceramic shell 4 is not completely dried, a water content of the to-be-dried ceramic shell may not be too high, and drying may be continued in a later drying process such that drying is completed.

[0116] The disclosure illustratively provides a method A for fan set control analysis. The method includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 3.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 3.2, k S-p %=D p / D 0 *100% is computed, where k S-p % denotes control parameters of the fan sets p. Step 3.3, step 3.1 to step 3.2 are repeated until k S-p % of all the fan sets is obtained.

[0117] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p% =[1-D 0 / (D 0 +1)]*100% is computed, where k F-p % denotes control parameters of the fan sets p.

[0118] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0119] For instance, a total number of all deep holes in the to-be-dried ceramic shell 4 satisfies D 0 =4, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=1 satisfies D 1 =1, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=2 satisfies D 2 =1, a total number of all deep holes in the surface of the to-be-dried ceramic shell 4 facing the fan set p=3 satisfies D 3 =2, and the remaining to-be-dried ceramic shells 4 have no deep holes in the surfaces and are provided with corresponding fan sets p=4, p=5 and p=6.

[0120] In this case, the following is computed: k S − 1 % = D 1 / D 0 * 100 % = 1 / 4 * 100 % = 25 % , k S − 2 % = D 2 / D 0 * 100 % = 1 / 4 * 100 % = 25 % , k S − 3 % = D 3 / D 0 * 100 % = 2 / 4 * 100 % = 50 % , and k F − 4 % = k F − 5 % = k F − 6 % = 1 − D 0 / D 0 + 1 * 100 % = 1 − 4 / 5 * 100 % = 20 % .

[0121] Through the method for fan set control analysis of the instance of the disclosure, a running condition of each fan set may be automatically and adaptively adjusted according to the acquired deep hole distribution of the to-be-dried ceramic shell 4. In this way, wind exposure of a portion having more deep holes in the to-be-dried ceramic shell 4 is improved, and a drying speed is high, which is conducive to rapid drying in the deep holes. However, in a portion having few or no deep holes, a degree of wind exposure decreases accordingly, and a drying speed is decreased, which is conducive to synchronization with drying time of the deep holes. Thus, drying is completed in a short drying time on the basis of ensuring that drying degrees of all the portions of the to-be-dried ceramic shell 4 tend to be identical.

[0122] Moreover, the method is only related to a number and positions of the deep holes in the to-be-dried ceramic shell 4. For to-be-dried ceramic shells 4 having various types of structures, such as a standard or non-standard structure, the drying time may be preferably controlled to be short, and the drying time of all the portions of the ceramic shell may be preferably controlled to tend to be identical.

[0123] The disclosure illustratively provides a method B for fan set control analysis. The method includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 4.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 4.2, k S-p % is acquired from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p. Step 4.3, step 4.1 to step 4.2 are repeated until k S-p % of all the fan sets is obtained.

[0124] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p % is acquired from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4, where the k F-p % denotes the control parameters of the fan sets p.

[0125] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p %.

[0126] The disclosure illustratively provides a method for inputting k S-p % and k F-p % into the control parameter database. The method includes: Step 5.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 5.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and the control parameters k S-p % and k F-p % in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution are determined, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 5.3, step 5.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D 0 -D p -k S-p% -k F-p % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0127] Through the method for fan set control analysis of the instance of the disclosure, a large number of deep hole-control parameter relation sets related to a comprehensive and optimal situation may be prepared in a database of the vacuum drying system through preliminary experiments. In this way, after the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 and the total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p are acquired, the corresponding fan set may be controlled with optimal k S-p % and k F-p % theoretically related to D 0 -D p according to the pre-stored deep hole-control parameter relation set in the control parameter database.

[0128] An optimal result of an experiment is as follows: under a specific deep hole relation set of D 0 -D p , the fan set is controlled to run with the control parameters of k S-p %-k F-p %, such that the drying time may be the shortest on the basis of ensuring that the drying degrees of all the portions of the to-be-dried ceramic shells 4 tend to be identical. The drying time is closely related to a size, a surface area and a surface structure of the to-be-dried ceramic shell 4, so the method needs to be determined together with a digital model structure of the to-be-dried ceramic shell 4. A standard to-be-dried ceramic shell 4 is a common component, and may be subjected to experimental simulation in advance. A non-standard to-be-dried ceramic shell 4 is a special-shaped member designed as required, and has various structural modes, which may not be covered by preliminary tests. In a case that the control parameter database lacks a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % corresponding to the special-shaped to-be-dried ceramic shell 4, the method B for fan set control analysis of the instance fails to acquire the required deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p %. In this case, the method A for fan set control analysis of the instance should be used to obtain the deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % corresponding to the special-shaped to-be-dried ceramic shell 4 after analysis.

[0129] The method B for fan set control analysis of the instance and the method A for fan set control analysis of the instance may be used separately or jointly.

[0130] The disclosure illustratively provides a fan set. At least two fans are arranged and mounted in the fan set. The fan set control module synchronously or independently controls the fans in each fan set.

[0131] The disclosure illustratively provides a method C for fan set control analysis based on a case that a fan set is internally provided with at least two fans. Based on the method A for fan set control analysis or the method B for fan set control analysis, the method further includes: Step 6.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 6.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 6.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 6.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 6.5, k up-e %=(D up-e / D up )*k S-p % is computed.

[0132] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0133] For instance, the fan set p includes two fans, which are numbered p-1 and p-2 respectively. The fans are fixed relative to the scanning starting point preset by the scanning device 207, so coordinate positions of the fans p-1 and p-2 in the three-dimensional coordinate system created in step 6.1 are also fixed. In this case, the fan p-1 may form a cylindrical air duct p-1 with a fan shaft axis as a central axis and a diameter R=100 cm in the three-dimensional coordinate system. An intersection surface of the cylindrical air duct p-1 and a corresponding surface of the to-be-dried ceramic shell 4 is a coordinate system range U p-1 covered by the fan p-1, and a number D up-1 of deep holes in U p-1 is counted. For instance, D up-1 =1, D up-2 =2, and a number D up of deep holes in the entire coverage of the fan set p is 3 for instance. Thus, the following may be computed: k up − 1 % = D up − 1 / D up * k S − p % = 1 / 3 * k S − p % , and k up − 2 % = D up − 2 / D up * k S − p % = 2 / 3 * k S − p % .

[0134] That is, in the fan set p, a fan 1 runs at a state of (1 / 3)* k S-p %, and a fan 2 runs at a state of (2 / 3)* k S-p %.

[0135] The method C for fan set control analysis of the instance of disclosure, separate control parameters of each fan in the fan set p may be obtained through computation, such that corresponding separate control of a plurality of fans in the fan set p is implemented. The method may make winds blown by the fan set p to the to-be-dried ceramic shell 4 more targeted, and make drying completion time of all the portions, especially a deep hole distribution zone and a non-deep hole distribution zone, of the to-be-dried ceramic shell 4 tend to be identical.

[0136] The disclosure illustratively provides a method D for fan set control analysis based on a case that a fan set is internally provided with at least two fans. Based on the method A for fan set control analysis or the method B for fan set control analysis, the method further includes: Step 7.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 7.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 7.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 7.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 7.5, k up-e % of the corresponding fan is acquired from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0137] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0138] The disclosure illustratively provides a method for inputting k up-e % into the control parameter database. The method specifically includes: Step 8.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 8.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution is determined. The deep hole distribution includes: an orientation and a number of the deep holes. The optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 8.3, step 8.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D up -D up-e -k up-e % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0139] Through the method for fan set control analysis of the instance of the disclosure, a large number of deep hole-control parameter relation sets of D up -D up-e -k up-e % related to a comprehensive and optimal situation may be prepared in a database of the vacuum drying system through preliminary experiments. In this way, in response to determining the coordinate system range U p-e covered by a blowing orientation of each fan in the fan set p, the number D up-e of deep holes in a coverage range of U p-e , and a number D up of deep holes in the entire coverage range of the fan set p, each fan may be controlled separately with fan control parameters corresponding to optimal k up-e % related to D up -D up-e theoretically according to the deep hole-control parameter relation set of D up -D up-e -k up-e % pre-stored in the control parameter database.

[0140] Similar to the method B for fan set control analysis of the instance, the method D for fan set control analysis of the instance is mainly suitable for the to-be-dried ceramic shell 4 having a model structure covered by preliminary simulation experiments. For the to-be-dried ceramic shell 4 having a model structure not covered by preliminary simulation experiments, the deep hole-control parameter relation set of D up -D up-e -k up-e % is obtained through the method C for fan set control analysis of the instance.

[0141] The disclosure illustratively provides a vacuum rapid drying system. The vacuum rapid drying system includes: a first data transmission module, a local database module, and a remote system module.

[0142] The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0143] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set and running result data.

[0144] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0145] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0146] For instance, if each vacuum rapid drying system is networked with the remote system module through the Internet, an optimal result corresponding to the deep hole-control parameter relation set D up -D up-e -k up-e % recorded by the local database module of each vacuum rapid drying system for a model A is B. In this case, an enterprise or apparatus manufacturer finds by experiment or chance that the control parameters in the deep hole-control parameter relation set D up -D up-e -k up-e % are adjusted to k up-e% ', and a result C superior to the optimal result B may be obtained. In this case, a new deep hole-control parameter relation set D up -D up-e -k up-e %' recorded for the model A and the corresponding optimal result C are collected centrally through the remote system module of the disclosure, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0147] Through the data synchronization method of the disclosure, optimal control parameters for a certain model obtained by an enterprise or apparatus manufacturer may be synchronized into all other networked vacuum rapid drying systems, such that an optimization degree of the control parameters for the model under a D up -D up-e condition is improved, and drying efficiency is enhanced. Thus, the disclosure can continuously optimize and improve the control parameters of the fan set and all the fans in the fan set in an actual running process, enhance overall drying efficiency, and improve enterprise benefits.

[0148] The disclosure illustratively provides a vacuum rapid drying system. The vacuum rapid drying system includes: a second data transmission module and a remote system module.

[0149] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0150] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0151] The vacuum rapid drying system of the instance may run with intervention of the remote system module, such that the vacuum rapid drying system is remotely controlled. For instance, the method can make a supplier conveniently remotely control and self-check an apparatus for a user, and improve efficiency of early apparatus adjustment and later apparatus maintenance.

[0152] The disclosure illustratively provides a drying frame 3. The drying frame includes: a ceramic shell hanger 304 configured to hang the to-be-dried ceramic shell 4. The ceramic shell hanger 304 is provided with a plurality of hook recesses 305. The to-be-dried ceramic shell 4 is hooked at the hook recesses 305 through hooks 11. A hanger support 302 is fixed to a bottom of the ceramic shell hanger 304. A bottom of the hanger support 302 is provided with a plurality of rollers 303 slidable along a guide rail 301. The guide rail 301 is fixed to a bottom surface in the vacuum drying chamber 1.

[0153] A preparing process of the ceramic shell involves repeated slurry application and corresponding drying operations. Thus, the to-be-dried ceramic shell 4 needs to be conveniently and detachably fixed to both the ceramic shell hanger 304 and the vacuum drying chamber 1. The disclosure provides a method for detachably fixing the to-be-dried ceramic shell 4 to the ceramic shell hanger 304 and the vacuum drying chamber 1. Specifically, the to-be-dried ceramic shell 4 may be hooked at the hook recesses 305 through the hooks 11, such that the to-be-dried ceramic shell 4 may be conveniently and detachably fixed to the ceramic shell hanger 304 through hooking / detachment. Then, the ceramic shell hanger 304 slides into / out of the guide rail 301, such that the to-be-dried ceramic shell 4 may be conveniently and detachably fixed to the vacuum drying chamber 1.

[0154] The disclosure illustratively provides a guide rail 301. The guide rail 301 is provided with a limiting block at one side away from an opening and closing door of the vacuum drying chamber 1. As shown in FIG. 1, the guide rail 301 is provided with a limiting block at one side close to an adjustable member 108. The arrangement can make a sliding position of the ceramic shell hanger 304 in the vacuum drying chamber 1 relatively fixed, such that a number of to-be-dried ceramic shells 4 faced by the fan set in each drying process is similar, and drying stability is improved.

[0155] The disclosure illustratively provides a scanning device 207. The scanning device 207 includes: a thermal imager 2072. A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: Step 9.1, the thermal imager 2072 performs real-time thermal imaging photographing on the to-be-dried ceramic shell 4 along with the scanning device 207 in a drying process of the to-be-dried ceramic shell 4, and sends an image obtained through real-time thermal imaging photographing to the control system. Step 9.2, the control system determines whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and in response to determining that there is the zone T, the following determination and operations are performed: in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T is reduced; in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T is enhanced; and in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T is enhanced.

[0156] The disclosure illustratively provides a preset low-temperature threshold, which is 12°C-15°C.

[0157] The disclosure illustratively provides a preset high-temperature threshold, which is 26°C-28°C.

[0158] The disclosure illustratively provides preset first drying time, which is 1 min-3 min.

[0159] The disclosure illustratively provides a preset time threshold, which is 30 s-60 s.

[0160] It is one of main to-be-solved problems of the disclosure to make drying degrees of all the portions of the to-be-dried ceramic shell 4 tend to be identical and make the drying time of all the portions of the to-be-dried ceramic shell 4 tend to be identical. Through a method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical of the instance of the disclosure, the control parameters of each fan set may be dynamically adjusted based on temperature changes of all the portions in a thermal image of the to-be-dried ceramic shell 4 in the drying process, such that the drying time of all the portions of the to-be-dried ceramic shell 4 tends to be more identical in the drying process.

[0161] The disclosure illustratively provides a method for a vacuum rapid drying treatment. The method includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0162] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0163] In a case that a supporting layer is dried, the following steps are included: step 10.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min; step 10.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s; step 10.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s; and step 10.6, step 10.4 and step 10.5 are repeated until drying of the supporting layer is completed.

[0164] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0165] An existing vacuum rapid drying technology for the ceramic shell is mainly to rapidly dry a surface layer and a transition layer through a reciprocating operation of vacuumizing and recompressing based on a thin slurry ceramic shell. A supporting layer may expand under a reciprocating high negative pressure condition, so as to form a sponge-like structure, such that a breaking strength coefficient of the ceramic shell is reduced while a thickness of the ceramic shell is increased.

[0166] Compared with the existing vacuum rapid drying technology for the thin slurry ceramic shell, a thick slurry ceramic shell should be rapidly dried under simpler control conditions theoretically due to a low water content. For instance, CN201610416881.4 discloses a vacuum rapid drying method for a thin slurry ceramic shell. "In a case that a supporting layer of the ceramic shell is dried, firstly, a sealed cavity is subjected to pumping to a vacuum state of 300 mmHg-100 mmHg within 60 s and kept for 400 s-600 s, and then the sealed cavity is subjected to vacuum deflation, such that the sealed cavity returns to a normal pressure state; then, step b is started, in which the sealed cavity is subjected to pumping to a vacuum state of 300 mmHg-100 mmHg within 60 s, and then step c is performed; the sealed cavity is subjected to vacuum deflation within 120 s in step c, such that the sealed cavity returns to a normal pressure state, and then step b is restarted; and the supporting layer of the prepared ceramic shell has a sponge-like loose structure." According to common sense, in a case that a supporting layer of a thick slurry ceramic shell is dried, rapid drying may be implemented under simpler control conditions. For instance, pressure reduction may be performed in a slower time range of 90 s, and rapid drying may be implemented by performing pumping on the sealed cavity to a vacuum state of 500 mmHg-400 mmHg. However, in fact, after research, the applicant finds it more difficult to obtain a better dried thick slurry ceramic shell under a vacuum drying condition than a thin slurry ceramic shell. For instance, in a case that a supporting layer of the thick slurry ceramic shell is dried, an environmental vacuum degree of the to-be-dried ceramic shell needs to be reduced from normal pressure to 260 mmHg-20 mmHg within 30 s and restored to normal pressure within 90 s. This is because the thick slurry ceramic shell has a low water content and a high content of sand or granular materials. Thus, flowing of water and air in the thick slurry ceramic shell is easily blocked, which leads to a problem that a surface of the ceramic shell is dry and water in the ceramic shell is not evaporated in the drying process. Thus, in a theoretically low control environment, evaporation efficiency of water in the thick slurry ceramic shell is quite different from theoretical efficiency, so it is necessary to make water and bubbles in the thick slurry ceramic shell flow effectively in a lower negative pressure environment at a higher pressure reduction speed. On one hand, a sponge-like structure uniformly distributed and caused by bubble flowing may be formed in the thick slurry ceramic shell in the drying process, and a thickness of a ceramic shell layer may be expanded. On the other hand, water in the thick slurry ceramic shell may be effectively discharged, such that rapid drying may be implemented in a real sense.

[0167] The disclosure illustratively provides a method for drying supporting layers. At least three supporting layers are sequentially arranged from a transition layer to a sealing layer.

[0168] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0169] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0170] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0171] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0172] According to the vacuum rapid drying method of the instance of the disclosure, in a vacuum drying process, the supporting layer of the thick slurry ceramic shell can have a better drying speed on one hand. On the other hand, the dried ceramic shell has a desirable breaking strength coefficient and can provide a sufficient supporting force, thus satisfying use requirements of precision casting.

[0173] The disclosure illustratively provides a vacuum rapid drying system. As shown in FIG. 1, the vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0174] The to-be-dried ceramic shell 4 is put into the vacuum drying chamber 1 for the vacuum rapid drying treatment.

[0175] The control system controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10 and the second electronic control valve 107, so as to implement method steps of the vacuum rapid drying treatment.

[0176] The vacuum rapid drying system further includes: a vacuum tank 5. One end of the vacuum tank 5 is in communication with the vacuum pump 8 through a second connecting tube. The second connecting tube is provided with a third electronic control valve 9. The other end of the vacuum tank 5 is in communication with the vacuum drying chamber 1 through a third connecting tube 7. The third connecting tube 7 is provided with a fourth electronic control valve 6.

[0177] The disclosure illustratively provides a method for pressure reduction in a case that vacuum drying is performed on supporting layers and a sealing layer. The method includes: an instantaneous pressure reduction operation. The instantaneous pressure reduction operation includes: the fourth electronic control valve 6 is firstly closed before pressure reduction, and pumping is performed on the vacuum tank 5 to a low vacuum state in advance; then, the fourth electronic control valve 6 is opened during pressure reduction, such that the vacuum drying chamber 1 is in communication with the vacuum tank 5, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally, the vacuum pump 8 simultaneously extracts gas-phase components in the vacuum tank 5 and the vacuum drying chamber 1, the fourth electronic control valve 6 and the first electronic control switching valve 10 are closed after a vacuum degree in the vacuum drying chamber 1 satisfies a preset target, and meanwhile, the vacuum pump 8 continues to extract the gas-phase components in the vacuum tank 5 until the vacuum tank 5 is in the low vacuum state.

[0178] The disclosure illustratively provides a method for vacuum rapid drying of supporting layers and a sealing layer by combining an instantaneous pressure reduction operation. At least three supporting layers are sequentially arranged from a transition layer to the sealing layer.

[0179] An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 14.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 14.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.6, step 14.4 and step 14.5 are repeated until drying of the first layer of the supporting layers is completed.

[0180] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 15.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 15.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.6, step 15.4 and step 15.5 are repeated until drying of the second layer of the supporting layers is completed.

[0181] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 16.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 16.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.4, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.6, step 16.4 and step 16.5 are repeated until drying of the third layer of the supporting layers is completed.

[0182] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer includes the following steps: Step 17.1, the instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 17.2, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 120 s, and the vacuum tank 5 continues to be vacuumized. Step 17.3, step 17.1 and step 17.2 are repeated until drying of the sealing layer is completed.

[0183] The technology of the disclosure combines a specific instantaneous pressure reduction operation, such that drying time of a thick slurry shell film can be further shortened, the breaking strength coefficient can be further reduced, and an average thickness of the supporting layer of the ceramic shell can be further increased. In this way, the sufficient supporting force is kept, and meanwhile, the thick slurry ceramic shell further has an excellent breaking strength coefficient, thus improving an application field of the thick slurry ceramic shell in precision casting.

[0184] In order to explain the technical solution of the disclosure in more detail, the technology of the disclosure will be further described in detail with specific examples and comparative examples.Slurry preparation:

[0185] (1) Thick slurry A was ceramic shell slurry compounded by ceramic shell sol, powder, water and sand, and satisfied the following condition: a concentration of each layer of ceramic shell slurry was expressed by a Zahn cup method with a No.4 Zahn measuring cup, where a concentration of ceramic shell slurry of a surface layer was 58 s, a concentration of ceramic shell slurry of a transition layer was 32 s, a concentration of ceramic shell slurry of a supporting layer was 24 s, and a concentration of ceramic shell slurry of a sealing layer was 11 s. The sealing layer included no sand. Sand of 100 meshes was selected for covering a to-be-dried ceramic shell at the surface layer with sand. Sand of 60 meshes was selected for covering a to-be-dried ceramic shell at the transition layer with sand. Sand of 30 meshes was selected for covering a to-be-dried ceramic shell at the supporting layer with sand. The ceramic shell sol was silica sol, and a mass concentration of silicon dioxide was 25%. The powder was zirconium powder of 300 meshes. (2) Thin slurry was ceramic shell slurry compounded by ceramic shell sol, powder, water and sand, and satisfied the following condition: a concentration of each layer of ceramic shell slurry was expressed by a Zahn cup method with a No.4 Zahn measuring cup, where a concentration of ceramic shell slurry of a surface layer was 45 s, a concentration of ceramic shell slurry of a transition layer was 26 s, a concentration of ceramic shell slurry of a supporting layer was 14 s, and a concentration of ceramic shell slurry of a sealing layer was 11 s. The sealing layer included no sand. Sand of 100 meshes was selected for covering a to-be-dried ceramic shell at the surface layer with sand. Sand of 60 meshes was selected for covering a to-be-dried ceramic shell at the transition layer with sand. Sand of 30 meshes was selected for covering a to-be-dried ceramic shell at the supporting layer with sand. The ceramic shell sol was silica sol, and a mass concentration of silicon dioxide was 25%. The powder was zirconium powder of 300 meshes. Testing method:(1) Breaking strength coefficient:

[0186] A same batch of ceramic shells were taken and subjected to dewaxing and high temperature treatment at 1050°C for 1.5 h so as to obtain ceramic shells for casting. Thus, maximum pressure borne by the ceramic shells when the ceramic shells for casting were destroyed was used as a breaking strength coefficient. An average breaking strength coefficient of at least 5 ceramic shells in the same batch was used as the breaking strength coefficient of the example or comparative example of the disclosure.(2) Ceramic shell thickness:

[0187] A same batch of ceramic shells were taken and subjected to dewaxing and high temperature treatment at 1050°C for 1.5 h so as to obtain ceramic shells for casting. An average value of ceramic shell thicknesses at casting ports of at least 5 of the ceramic shells for casting was a ceramic shell thickness of the disclosure with a unit of cm.(3) Drying time:

[0188] An average value of drying time of each layer of a to-be-dried ceramic shell 4 from a surface layer to a sealing layer was rounded, and was the drying time of the disclosure with a unit of min. The drying time of each layer was: time consumed by putting the to-be-dried ceramic shell 4 of a corresponding layer into a vacuum rapid drying system until drying of the layer was completed.(4) Drying yield:

[0189] Q%=(a number of qualified ceramic shells dried in the batch) / (a number of all ceramic shells in the batch)*100%, which was rounded. A criterion for determining whether drying of a ceramic shell is qualified was that a dried ceramic shell was not overdried, and a humidity at a deep hole and a surface humidity of the ceramic shell were both lower than 3%.

[0190] A method 1 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry.

[0191] During the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical.

[0192] S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0193] The vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, a control system, a first data transmission module, a second data transmission module, a local database module, and a remote system module. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107. The first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner.

[0194] The local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set and running result data.

[0195] The remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation. Based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module.

[0196] In response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

[0197] The remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system.

[0198] An execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

[0199] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3. A bottom of the drying frame 3 is provided with a second air blower set 102. The drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively. An opposite side of the third air blower set 103 is provided with an adjustable member 108. The adjustable member 108 is: a sixth air blower set.

[0200] As shown in FIGs. 1-2, the drying frame 3 includes: a ceramic shell hanger 304 configured to hang the to-be-dried ceramic shell 4. The ceramic shell hanger 304 is provided with a plurality of hook recesses 305. The to-be-dried ceramic shell 4 is hooked at the hook recesses 305 through hooks 11. A hanger support 302 is fixed to a bottom of the ceramic shell hanger 304. A bottom of the hanger support 302 is provided with a plurality of rollers 303 slidable along a guide rail 301. The guide rail 301 is fixed to a bottom surface in the vacuum drying chamber 1.

[0201] The guide rail 301 is provided with a limiting block at one side away from an opening and closing door of the vacuum drying chamber 1. As shown in FIG. 1, the guide rail 301 is provided with a limiting block at one side close to an adjustable member 108.

[0202] The vacuum drying chamber 1 is internally provided with a three-dimensional detection mechanism 2. As shown in FIGs. 1-4, the three-dimensional detection mechanism 2 includes: two X-axis guide rails 201 that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber 1 and located at two sides of the drying frame 3 respectively, and a Y-axis guide rail 202 horizontally arranged along a section of the vacuum drying chamber 1. The two X-axis guide rails 201 are provided with first displacement devices 203 movable along the X-axis guide rails 201 respectively. The Y-axis guide rail 202 is fixedly arranged between the two first displacement devices 203 and is driven to move along the X-axis guide rails 201 by the two first displacement devices 203. The Y-axis guide rail 202 is provided with a second displacement device 204 movable along the Y-axis guide rail 202. The second displacement device 204 is vertically provided with an electronic control telescopic device 205 that expands and shrinks in a Z-axis direction. A tail end of a telescopic end of the electronic control telescopic device 205 is fixedly provided with the scanning device 207 through an electronic control pan-tilt 206. The first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206 are connected to the control system in a signal manner separately.

[0203] As shown in FIG. 5, the electronic control pan-tilt 206 includes: a fixing platform 2061 fixed to the electronic control telescopic device 205 and a rotating platform 2062 rotatably connected to the fixing platform 2061 and rotating along a vertical axis relative to the fixing platform 2061. The rotating platform 2062 is rotatably connected to a fixed end of a second electronic control telescopic device 2064 through a reducer 2063. The reducer 2063 controls the second electronic control telescopic device 2064 to rotate along a horizontal axis. A telescopic end of the second electronic control telescopic device 2064 is fixed to the scanning device 207.

[0204] As shown in FIG. 6, the scanning device 207 includes: a photographing device 2071, a thermal imager 2072, a scanning and distance measuring device 2073, and an infrared temperature measuring device 2074. The photographing device 2071 is configured to acquire image data of the to-be-dried ceramic shell 4. The scanning and distance measuring device 2073 is configured to measure a distance of the to-be-dried ceramic shell 4 from the scanning device 207 in real time.

[0205] The control system includes: a vacuum drying control module, a fan set control module, a ceramic shell analysis module, a scanning device control module, and a drying process analysis module.

[0206] The vacuum drying control module controls opening and closing of the vacuum pump 8, the first electronic control switching valve 10, and the second electronic control valve 107.

[0207] The ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell 4 and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell 4, and same are sent to the fan set control module. The fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell 4 and then controls starting and stopping and / or control parameters of each fan set according to an analysis result.

[0208] The scanning device control module is configured to control movement of the two first displacement devices 203, the second displacement device 204, the electronic control telescopic device 205 and the electronic control pan-tilt 206, such that the scanning device 207 photographs / scans the to-be-dried ceramic shell 4 in all directions, and image / scanning data of the to-be-dried ceramic shell 4 is obtained.

[0209] The drying process analysis module acquires a measurement quantity of the infrared temperature measuring device 2074 for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell 4 is completed.

[0210] A method for model structure analysis includes: Step 1.1, the scanning and distance measuring device 2073 scans a surface n of the to-be-dried ceramic shell 4 in all directions according to a preset line, and a distance measuring data set G n of all scanning points on the surface n from the scanning and distance measuring device 2073 is acquired. Step 1.2, end points of the distance measuring data set G n are connected, and a digital surface m of the surface n of the to-be-dried ceramic shell 4 is obtained. Step 1.3, graphic analysis is performed on the digital surface m of the to-be-dried ceramic shell 4 by combining the image data, and a basic surface, a protruding surface and a recess surface of the digital surface m are determined. Step 1.4, a difference C mk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess is computed, where mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk. Step 1.5, C mk-b >K 2 is used as a deep hole and C mk-b >K 3 is used as a through hole. K 2 denotes a preset deep hole determination threshold, and K 3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell 4. Step 1.6, positions W mc of all deep holes in the digital surface m of the to-be-dried ceramic shell 4 and a depth H mc corresponding to each deep hole are counted, where c denotes a natural number of the deep hole in the digital surface m. Step 1.7, step 1.1 to step 1.6 are repeated until positions W mc and depths H mc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell 4 are counted, and an orientation X mc of the deep hole is determined according to the surface n where the deep hole is located. Step 1.8, data of positions W mc , depths H mc and orientations X mc of all deep holes in the surface of the to-be-dried ceramic shell 4 are output. Step 2.1, a scanning and distance measuring device 2073 is controlled to move to the position of the deep hole according to the position of the deep hole. Step 2.2, depth measurement data of a plurality of deep holes is acquired by adjusting orientations of the scanning and distance measuring device 2073 relative to the deep holes. Step 2.3, depth data H m-c of an original deep hole is corrected with depth measurement data having a maximum depth, and corrected data H m-c ' is obtained.

[0211] A method for acquiring the basic surface, the protruding surface and the recess surface includes: Step 1.3.1, the image data corresponding to the digital surface m of the to-be-dried ceramic shell 4 is acquired, and the image data is spliced so as to obtain an image surface R. Step 1.3.2, element identification is performed on the image surface R, and an element zone rn-m on the image surface R is obtained, where rn denotes a sequence number of the element zone in the digital surface m. Step 1.3.3, the digital surface m is adjusted to have a same orientation and a similar size to the image surface R. Step 1.3.4, an element zone rc-m having a maximum continuous area is used as the basic surface, where the rc-m belongs to rn-m. Step 1.3.5, distance measuring point data of an element zone of each non-basic surface is acquired, where a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point. Step 1.3.6, the element zone is used as a boundary, and adjacent recess point and protruding point are connected to form the recess surface and the protruding surface.

[0212] The drying process analysis includes the following steps: an internal temperature T of the deep hole is measured regularly or continuously; and a curve Qv of deep hole temperature T V -drying time t is made. In response to determining that a curve segment conforming to a preset curve rule appears in Qv, it is indicated that drying of the to-be-dried ceramic shell 4 is completed, where v denotes a natural number of all the deep holes of the to-be-dried ceramic shell 4.

[0213] As shown in FIG. 9, the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T 1 to a temperature T 2 with the drying time, and then gradually increases to a drying environment temperature T 3 with the drying time. In response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell 4 changes from T 1 to T 2 and to T 3 and is kept at the drying environment temperature T 3 for preset time U, it is determined that drying is completed. The initial drying temperature T 1 is 22°C-26°C. The temperature T 2 is 5°C-7°C lower than the temperature T 1 . The drying environment temperature T 3 is 24±1°C.

[0214] In response to determining that a plurality of to-be-dried ceramic shells 4 are provided, a method for determining whether drying of the to-be-dried ceramic shells 4 is completed includes the following steps: temperatures of all the deep holes of all the to-be-dried ceramic shells 4 are measured one by one; and in response to determining that drying of more than L% of the to-be-dried ceramic shells 4 is completed, it is determined that drying of an entire batch of to-be-dried ceramic shells 4 is completed. L%=(L g-d ) / (L 0-d )*100%, where L g-d denotes a number of to-be-dried ceramic shells 4 of a batch d after drying is completed, and L 0-d denotes a number of all to-be-dried ceramic shells 4 of the batch d. A value of L% is: 100%≥L%≥E%. E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells 4 of the batch d.

[0215] The fan set control analysis includes: a method A for fan set control analysis, a method B for fan set control analysis, a method C for fan set control analysis, and a method D for fan set control analysis, where the method A for fan set control analysis includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: step 3.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1; step 3.2, k S-p %=D p / D 0 *100% is computed, where k S-p % denotes control parameters of the fan sets p; and step 3.3, step 3.1 to step 3.2 are repeated until k S-p % of all the fan sets is obtained.

[0216] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p %=[1-D 0 / (D 0 +1)]*100% is computed, where k F-p % denotes control parameters of the fan sets p; and the fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p % .

[0217] The method B for fan set control analysis includes: In a case that all fan sets p face the to-be-dried ceramic shells 4 having deep holes in surfaces, the following method is used: Step 4.1, a total number D 0 of all the deep holes of the to-be-dried ceramic shells 4 is acquired, and a total number D p of all the deep holes in the surfaces of the to-be-dried ceramic shells 4 faced by the fan sets p is acquired, where p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber 1. Step 4.2, k S-p % is acquired from a control parameter database according to the numbers of D 0 and D p , where the k S-p % denotes the control parameters of the fan sets p. Step 4.3, step 4.1 to step 4.2 are repeated until k S-p % of all the fan sets is obtained.

[0218] In a case that all fan sets p face the to-be-dried ceramic shells 4 having no deep holes in surfaces, the following method is used: k F-p % is acquired from the control parameter database according to the total number D 0 of all the deep holes of the to-be-dried ceramic shells 4, where the k F-p % denotes the control parameters of the fan sets p.

[0219] The fan set control module sends obtained k S-p % and k F-p % of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full k S-p % or k F-p % .

[0220] A method for inputting k S-p % and k F-p % into the control parameter database includes: Step 5.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 5.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and the control parameters k S-p % and k F-p % in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution are determined, where the deep hole distribution includes: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 5.3, step 5.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D 0 -D p -k S-p %-k F-p % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0221] The method C for fan set control analysis includes: Step 6.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 6.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 6.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 6.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 6.5, k up-e %=(D up-e / D up )* k S-p % is computed.

[0222] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %. The fan corresponding to D up-e =0 runs at minimum power.

[0223] The method D for fan set control analysis includes: Step 7.1, a three-dimensional coordinate system is created based on a scanning starting point preset by the scanning device 207. Step 7.2, the scanning device 207 records a three-dimensional coordinate point in a space in a displacement process, and three-dimensional coordinate point marking is performed on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell 4 in a model structure analysis process. Step 7.3, a coordinate system range U p-e covered by an air blowing orientation of each fan in the fan set p is acquired, where e denotes a natural number of the fans in the fan set p. Step 7.4, a number D up-e of deep holes in coverage U p-e and a number D up of deep holes in entire coverage of the fan set p are counted. Step 7.5, k up-e % of the corresponding fan is acquired from the control parameter database according to D up and D up-e , where the k up-e % denotes the control parameters of the fan numbered e in the fan set p.

[0224] The fan set control module sends obtained k up-e % of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full k up-e %.

[0225] A method for inputting k up-e % into the control parameter database specifically includes: Step 8.1, a same position and orientation of the fan set as a target vacuum drying chamber 1 are simulated in a simulation apparatus. Step 8.2, a deep hole distribution of different to-be-dried ceramic shells 4 is preset for drying training, and a running ratio k up-e % in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution is determined. The deep hole distribution includes: an orientation and a number of the deep holes. The optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells 4. Step 8.3, step 8.2 is repeated until training of the deep hole distribution under a normal condition is completed, a deep hole-control parameter relation set of D up -D up-e -k up-e % is created, and the deep hole-control parameter relation set is stored in the control parameter database.

[0226] Drying of the to-be-dried ceramic shell 4 with input data in the control parameter database is performed through methods B+D for fan set control analysis. Drying of the to-be-dried ceramic shell 4 without input data in the control parameter database is performed through methods A+C for fan set control analysis.

[0227] A method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical includes: Step 9.1, the thermal imager 2072 performs real-time thermal imaging photographing on the to-be-dried ceramic shell 4 along with the scanning device 207 in a drying process of the to-be-dried ceramic shell 4, and sends an image obtained through real-time thermal imaging photographing to the control system. Step 9.2, the control system determines whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and in response to determining that there is the zone T, the following determination and operations are performed: in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T is reduced; in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T is enhanced; and in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T is enhanced.

[0228] The preset low-temperature threshold is 14°C.

[0229] The preset high-temperature threshold is 27°C.

[0230] The preset first drying time is 2 min.

[0231] The preset time threshold is 50 s.

[0232] After the to-be-dried ceramic shell is put into the vacuum rapid drying system, the vacuum rapid drying treatment is performed after standing is performed for 60 s. A method for the vacuum rapid drying treatment includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0233] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0234] At least three supporting layers are sequentially arranged from a transition layer to a sealing layer. A method for drying the supporting layers includes the following steps: An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0235] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0236] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0237] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0238] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0239] A method 2 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry. S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0240] The vacuum rapid drying system includes: a vacuum drying chamber 1, a vacuum pump 8, and a control system. The vacuum pump 8 vacuumizes the vacuum drying chamber 1. The vacuum pump 8 is in communication with the vacuum drying chamber 1 through a first connecting tube. The first connecting tube is provided with a first electronic control switching valve 10. The vacuum drying chamber 1 is in communication with an air tube 106. The air tube 106 is provided with a second electronic control valve 107.

[0241] The vacuum drying chamber 1 is internally detachably provided with a drying frame 3. A to-be-dried ceramic shell 4 is detachably arranged on the drying frame 3 so as to be dried. The vacuum drying chamber 1 is internally provided with a first air blower set 101 on a top of the drying frame 3. A bottom of the drying frame 3 is provided with a second air blower set 102. The drying frame 3 is provided with a third air blower set 103 arranged on an opening and closing door of the vacuum drying chamber 1 along a section of the vacuum drying chamber 1. The drying frame 3 is provided with a fourth air blower set 104 and a fifth air blower set 105 at two sides of the vacuum drying chamber 1 in an axial direction respectively. An opposite side of the third air blower set 103 is provided with an adjustable member 108. The adjustable member 108 is: a sixth air blower set.

[0242] After the to-be-dried ceramic shell is put into the vacuum rapid drying system, the vacuum rapid drying treatment is performed after standing is performed for 60 s. A method for the vacuum rapid drying treatment includes: In a case that a surface layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 750 mmHg-720 mmHg within 5 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 750 mmHg-720 mmHg to the normal pressure within 5 s; and the above process is circulated until drying of the surface layer is completed.

[0243] In a case that a transition layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 720 mmHg-680 mmHg within 7 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored from 720 mmHg-680 mmHg to the normal pressure within 7 s; and the above process is circulated until drying of the transition layer is completed.

[0244] At least three supporting layers are sequentially arranged from a transition layer to a sealing layer. A method for drying the supporting layers includes the following steps: An inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 11.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 11.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 260 mmHg-220 mmHg within 30 s. Step 11.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s. Step 11.6, step 11.4 and step 11.5 are repeated until drying of the first layer of the supporting layers is completed.

[0245] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 12.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 12.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 200 mmHg-150 mmHg within 30 s. Step 12.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s. Step 12.6, step 12.4 and step 12.5 are repeated until drying of the second layer of the supporting layers is completed.

[0246] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 13.1, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.2, the environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min. Step 13.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.4, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from normal pressure to 80 mmHg-20 mmHg within 30 s. Step 13.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s. Step 13.6, step 13.4 and step 13.5 are repeated until drying of the third layer of the supporting layers is completed.

[0247] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

[0248] In a case that a sealing layer is dried, an environmental vacuum degree of the to-be-dried ceramic shell is firstly reduced from normal pressure to 120 mmHg-90 mmHg within 40 s; then, the environmental vacuum degree of the to-be-dried ceramic shell is restored to the normal pressure within 120 s; and the above process is circulated until drying of the sealing layer is completed.

[0249] In a case of performing the vacuum rapid drying treatment, the control system controls the fan set in the vacuum rapid drying system to run at a fixed wind direction and rated power. It is determined that drying of each layer of ceramic shell is completed after drying for preset time according to work experience or work instructions.

[0250] A method 3 for preparing a ceramic shell includes: S1, an exterior of a wax pattern is smeared with corresponding layers of ceramic shell slurry layer by layer, where a to-be-dried ceramic shell is obtained at a corresponding layer each time after smearing of the ceramic shell slurry is completed. S2, the to-be-dried ceramic shell at each corresponding layer is put into a vacuum rapid drying system for a vacuum rapid drying treatment, and after drying of the ceramic shell at the layer is completed, same is smeared with a subsequent layer of ceramic shell slurry. S3, the ceramic shell for precision casting is obtained after completion of drying of the ceramic shells at all the layers.

[0251] S2 is performed with a rapid drying method and device for a ceramic shell of ZL201610416881.4.Example 1

[0252] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.Example 2

[0253] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.Example 3

[0254] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 3 for preparing the ceramic shell.Comparative Example 1

[0255] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thin slurry through a method 1 for preparing the ceramic shell. In order to achieve an equivalent supporting force of the ceramic shell obtained in Example 1, a number of supporting layers is 5.Comparative Example 2

[0256] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thin slurry through a method 3 for preparing the ceramic shell. In order to achieve an equivalent supporting force of the ceramic shell obtained in Example 1, a number of supporting layers is 5.Comparative Example 3

[0257] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry, and is dried at normal pressure and with 120°C hot air in a drying process.

[0258] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1-3 and Comparative Examples 1-3 are tested, and test results are shown in Table 1. Table 1 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1-3 and Comparative Examples 1-3Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 2785.450.82318-2586Example 3845.560.71240-18085Comparative Example 1705.130.96518-2595Comparative Example 2720.110.93220-12090Comparative Example 31061.090.501360 or above71%

[0259] As can be seen from the above table: (1) Through comparison between Example 1 and Example 2, it can be seen that compared with a technology of multi-directional fixed wind directions and fixed fan power, drying time of a ceramic shell of the disclosure is slightly improved by adjusting control parameters of fans in all directions during drying of the ceramic shell under the control of same control parameters such as a vacuum drying degree. However, drying time of all portions of the ceramic shell in a drying process of the ceramic shell of the disclosure is almost consistent, such that a drying yield of the ceramic shell is significantly improved. (2) Through comparison between Example 1 and Example 3, it can be seen that compared with an existing vacuum rapid drying technology, in a case that a thick slurry ceramic shell is dried, performance of the ceramic shell obtained by the disclosure is significantly improved, and a drying yield of the ceramic shell can also be significantly improved. A main reason why the drying time of Example 3 is unstable is that in the prior art, vacuum rapid drying is performed by fixing wind at two sides and rotating the ceramic shell. In a case that a deep hole faces a windward side, the drying time is relatively short. In a case that the deep hole faces a leeward side, the drying time is relatively long, and a problem of overdrying on the windward side is likely to be caused. That is, a drying yield of the ceramic shell is decreased. (3) Through comparison between Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the disclosure can promote expansion of a supporting layer of the ceramic shell to obtain the supporting layer of the ceramic shell having a greater thickness, and reduce a breaking strength coefficient of the ceramic shell. Due to less materials, a thickness of an expandable thin slurry ceramic shell is smaller than that of a thick slurry ceramic shell. Thus, in order to achieve a necessary thickness of the ceramic shell to support the ceramic shell with a sufficient supporting force, it is necessary to increase a number of supporting layers, resulting in an increase in overall drying time (a number of layers * drying time). (4) Through comparison between Example 1, Example 3 and Comparative Example 3, it can be seen that a drying yield of the thick slurry ceramic shell prepared by the disclosure is significantly improved, which is mainly due to a fact that the drying time is significantly shortened while the disclosure ensures that a drying process tends to be identical. However, the drying time is too long in a case that the thick slurry ceramic shell is dried in the prior art. Drying of the ceramic shell is a cooling process of water volatilization. That is, a temperature of the ceramic shell may drop by about 6°C during volatilization of water of the ceramic shell. In this case, the wax pattern may be cooled and shrunk due to low temperature of the ceramic shell. Because drying of the ceramic shell is also a shrinking process, the ceramic shell may shrink with shrinkage of the wax pattern. In a case that the drying time is too long, a shrinkage ratio of the wax pattern may increase, leading to a great shrinkage ratio of the ceramic shell after drying. In a case that drying is completed and the entire ceramic shell returns to a room temperature, the wax pattern may expand and lead to cracks at a joint between a surface layer of the ceramic shell and the wax pattern, thus seriously influencing a drying yield of the ceramic shell. However, due to short drying time of the disclosure, a shrinkage ratio of the wax pattern due to influence of low temperature is small. Generally, cracks may not appear at the joint between the surface layer of the ceramic shell and the wax pattern, thus improving a drying yield of the thick slurry ceramic shell. Example 4

[0260] A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 6. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 4 for preparing the ceramic shell. Compared with a method 1 for preparing a ceramic shell, the method 4 for preparing a ceramic shell has the following differences: 1, A vacuum rapid drying system further includes: a vacuum tank 5. One end of the vacuum tank 5 is in communication with a vacuum pump 8 through a second connecting tube. The second connecting tube is provided with a third electronic control valve 9. The other end of the vacuum tank 5 is in communication with a vacuum drying chamber 1 through a third connecting tube 7. The third connecting tube 7 is provided with a fourth electronic control valve 6. 2, A method for vacuum rapid drying of supporting layers and a sealing layer includes: An inner surface of a first layer of the supporting layers is attached to an outer surface of a transition layer. A method for performing a vacuum rapid drying treatment of the first layer of the supporting layers includes the following steps: Step 14.1, an instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 14.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.4, an instantaneous pressure reduction operation is performed, an environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 14.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 40 s, and the vacuum tank 5 continues to be vacuumized. Step 14.6, step 14.4 and step 14.5 are repeated until drying of the first layer of the supporting layers is completed.

[0261] An inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the second layer of the supporting layers includes the following steps: Step 15.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 15.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.4, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 15.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 60 s, and the vacuum tank 5 continues to be vacuumized. Step 15.6, step 15.4 and step 15.5 are repeated until drying of the second layer of the supporting layers is completed.

[0262] An inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the third layer of the supporting layers includes the following steps: Step 16.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.2, an environmental vacuum degree of the to-be-dried ceramic shell is kept in a negative pressure state for 4 min-6 min, and the vacuum tank 5 continues to be vacuumized. Step 16.3, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.4, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 16.5, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 90 s, and the vacuum tank 5 continues to be vacuumized. Step 16.6, step 16.4 and step 16.5 are repeated until drying of the third layer of the supporting layers is completed.

[0263] An inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers. A method for performing a vacuum rapid drying treatment of the sealing layer includes the following steps: Step 17.1, the instantaneous pressure reduction operation is performed, the environmental vacuum degree of the to-be-dried ceramic shell is reduced from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, the vacuum tank 5 is kept vacuumized. Step 17.2, the environmental vacuum degree of the to-be-dried ceramic shell is restored to normal pressure within 120 s, and the vacuum tank 5 continues to be vacuumized. Step 17.3, step 17.1 and step 17.2 are repeated until drying of the sealing layer is completed. The instantaneous pressure reduction operation includes: the fourth electronic control valve 6 is firstly closed before pressure reduction, and pumping is performed on the vacuum tank 5 to a low vacuum state in advance; then, the fourth electronic control valve 6 is opened during pressure reduction, such that the vacuum drying chamber 1 is in communication with the vacuum tank 5, and balanced low pressure is instantaneously dropped to within 0.5 s; and finally, the vacuum pump 8 simultaneously extracts gas-phase components in the vacuum tank 5 and the vacuum drying chamber 1, the fourth electronic control valve 6 and the first electronic control switching valve 10 are closed after a vacuum degree in the vacuum drying chamber 1 satisfies a preset target, and meanwhile, the vacuum pump 8 continues to extract the gas-phase components in the vacuum tank 5 until the vacuum tank 5 is in the low vacuum state.

[0264] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1 and 4 are tested, and test results are shown in Table 2. Table 2 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1 and 4Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Total drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 4715.631.1338-1298

[0265] As can be seen from the above table: Through an instantaneous pressure reduction action, a breaking strength coefficient of the obtained ceramic shell can be further reduced, and a thickness of the obtained ceramic shell can be further increased. In this way, a sufficient supporting force is kept, and meanwhile, a thick slurry ceramic shell further has an excellent breaking strength coefficient, thus improving an application field of the thick slurry ceramic shell in precision casting.Example 5

[0266] As shown in FIG. 10, a structure of a ceramic shell has a conventional configuration and is provided with a holding part 402. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.Example 6

[0267] As shown in FIG. 10, a structure of a ceramic shell has a conventional configuration and is provided with a holding part 402. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.

[0268] Breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of the ceramic shells obtained in Examples 1-2 and 5-6 are tested, and test results are shown in Table 3. Table 3 Testing result table of breaking strength coefficients, ceramic shell thicknesses, total drying time and drying yields of Examples 1-2 and 5-6Breaking strength coefficient (Psi)Ceramic shell thickness (cm)Total drying time (min)Drying yield (%)Example 1785.230.82120-3098Example 2785.450.82318-2586Example 5788.040.81715-2099Example 6787.970.81815-2099

[0269] As can be seen from the above table: (1) In a case that a to-be-cast member has a simple configuration, compared with a technology of fixed wind directions, the disclosure achieves similar total drying time and drying yield. (2) In a case that a to-be-cast member has a complex configuration, compared with a technology of fixed wind directions, the disclosure may achieve slightly longer total drying time and an obviously improved drying yield.

[0270] It can be seen that the method for preparing a ceramic shell of the disclosure achieves similar preparing efficiency and preparing success rate to the technology of fixed wind directions in a case that the ceramic shell having a simple configuration is prepared, and may obviously improve a technical effect in a case that the ceramic shell having a complex configuration is prepared with a breaking coefficient. Thus, the method for preparing a ceramic shell of the disclosure not only makes the obtained ceramic shell have good performance, but also is suitable for preparing ceramic shells having various configurations. The method has wide applicability, and is especially suitable for preparing ceramic shells having a complex configuration.

[0271] Although the examples of the disclosure are illustrated and described, it should be understood that those of ordinary skill in the art can make various changes, modifications, replacements and variations to the examples without departing from the principle and spirit of the disclosure, and the scope of the disclosure is limited by the appended claims and their legal equivalents.

Examples

example 1

[0252]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 1 for preparing the ceramic shell.

example 2

[0253]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 2 for preparing the ceramic shell.

example 3

[0254]A structure of a ceramic shell includes a deep hole 401 and a holding part 402 as shown in FIG. 7. The deep hole 401 is of a casting structure. The holding part 402 is a component held by a worker during slurry application instead of a casting structure. The ceramic shell is prepared with thick slurry through a method 3 for preparing the ceramic shell.

Claims

1. A method for preparing a ceramic shell for precision casting, comprising: S1, smearing an exterior of a wax pattern with corresponding layers of ceramic shell slurry layer by layer, wherein a to-be-dried ceramic shell is obtained for each corresponding layer each time after smearing of the ceramic shell slurry is completed; S2, putting the to-be-dried ceramic shell of the corresponding layer into a vacuum rapid drying system for a vacuum rapid drying treatment, and smearing, after drying of the ceramic shell of the corresponding layer is completed, same with a subsequent layer of ceramic shell slurry, wherein during the vacuum rapid drying treatment, model information of the to-be-dried ceramic shell is first acquired, and then control parameters of each air blower in different side directions of the to-be-dried ceramic shell are adjusted according to the model information, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical; and the vacuum rapid drying system comprises: a vacuum drying chamber (1), a vacuum pump (8), and a control system, wherein the vacuum pump (8) vacuumizes the vacuum drying chamber (1); and the vacuum drying chamber (1) is internally provided with a drying frame (3), and a to-be-dried ceramic shell (4) is arranged on the drying frame (3) so as to be dried; and the vacuum drying chamber (1) is internally provided with at least two groups of fan sets having different wind directions around the drying frame (3); the control system comprises: a vacuum drying control module and a fan set control module; and the vacuum drying control module vacuumizes the vacuum drying chamber (1) and / or restores chamber pressure, and the fan set control module controls starting and stopping and / or control parameters of all fan sets, such that drying time of all portions of the entire to-be-dried ceramic shell tends to be identical; the vacuum drying chamber (1) is internally provided with a three-dimensional detection mechanism (2); and the three-dimensional detection mechanism (2) drives a scanning device (207) to move along an X axis, a Y axis, and a Z axis; the scanning device (207) at least comprises: a photographing device (2071); and the photographing device (2071) is configured to acquire image data of the to-be-dried ceramic shell (4); and the control system comprises: a ceramic shell analysis module, wherein the ceramic shell analysis module acquires the image data of the to-be-dried ceramic shell (4) and performs model structure analysis, so as to obtain a position, an orientation and a depth of a deep hole in the to-be-dried ceramic shell (4), and same are sent to the fan set control module; and the fan set control module performs fan set control analysis according to the position, the orientation and the depth of the deep hole in the to-be-dried ceramic shell (4) and then controls starting and stopping and / or control parameters of each fan set according to an analysis result; and S3, obtaining the ceramic shell for precision casting after completion of drying of the ceramic shells at all the layers.

2. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the vacuum pump (8) is in communication with the vacuum drying chamber (1) through a first connecting tube, and the first connecting tube is provided with a first electronic control switching valve (10); the vacuum drying chamber (1) is in communication with an air tube (106), and the air tube (106) is provided with a second electronic control valve (107); and the vacuum drying control module vacuumizes the vacuum drying chamber (1) and / or restores the chamber pressure by controlling starting and stopping of the vacuum pump (8), the first electronic control switching valve (10), and the second electronic control valve (107).

3. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the vacuum drying chamber (1) is provided with a controller assembly; the controller assembly receives and sends a control signal to the fan set control module, so as to control starting and stopping and / or the control parameters of each fan set; and a controller comprises: at least one of a knob controller, a key controller, a touch screen controller, and a toggle switch.

4. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the three-dimensional detection mechanism (2) comprises: two X-axis guide rails (201) that are parallel to each other, horizontally arranged in an axial direction of the vacuum drying chamber (1) and located at two sides of the drying frame (3) respectively, and a Y-axis guide rail (202) horizontally arranged along a section of the vacuum drying chamber (1); the two X-axis guide rails (201) are provided with first displacement devices (203) movable along the X-axis guide rails (201) respectively, and the Y-axis guide rail (202) is fixedly arranged between the two first displacement devices (203) and is driven to move along the X-axis guide rails (201) by the two first displacement devices (203); the Y-axis guide rail (202) is provided with a second displacement device (204) movable along the Y-axis guide rail (202); the second displacement device (204) is vertically provided with an electronic control telescopic device (205) that expands and shrinks in a Z-axis direction; a tail end of a telescopic end of the electronic control telescopic device (205) is fixedly provided with the scanning device (207) through an electronic control pan-tilt (206); and the first displacement devices (203), the second displacement device (204), the electronic control telescopic device (205) and the electronic control pan-tilt (206) are connected to the control system in a signal manner separately.

5. The method for preparing a ceramic shell for precision casting according to claim 4, wherein the control system comprises: a scanning device control module; and the scanning device control module is configured to control movement of the two first displacement devices (203), the second displacement device (204), the electronic control telescopic device (205) and the electronic control pan-tilt (206), such that the scanning device (207) photographs / scans the to-be-dried ceramic shell (4) in all directions, and image / scanning data of the to-be-dried ceramic shell (4) is obtained.

6. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the model structure analysis comprises image analysis as follows: firstly, acquiring outer contour model data, deep hole position data and deep hole depth data of the to-be-dried ceramic shell (4); then, comparing the acquired image data with the outer contour model data, and determining a spatial orientation of the to-be-dried ceramic shell (4) currently hanging in the vacuum drying chamber (1); and finally, determining a current position and orientation of a deep hole in the to-be-dried ceramic shell (4) according to the spatial orientation of the to-be-dried ceramic shell (4), and outputting the current position and orientation of the deep hole in the to-be-dried ceramic shell (4) and depth data corresponding to the deep hole.

7. The method for preparing a ceramic shell for precision casting according to claim 5, wherein the scanning device (207) further comprises: a scanning and distance measuring device (2073); and the scanning and distance measuring device (2073) is configured to measure a distance of the to-be-dried ceramic shell (4) from the scanning device (207) in real time; and the model structure analysis comprises: step 1.1, scanning, by the scanning and distance measuring device (2073), a surface n of the to-be-dried ceramic shell (4) in all directions according to a preset line, and acquiring a distance measuring data set Gn of all scanning points on the surface n from the scanning and distance measuring device (2073); step 1.2, connecting end points of the distance measuring data set Gn, and obtaining a digital surface m of the surface n of the to-be-dried ceramic shell (4); step 1.3, performing graphic analysis on the digital surface m of the to-be-dried ceramic shell (4) by combining the image data, and determining a basic surface, a protruding surface and a recess surface of the digital surface m; step 1.4, computing a difference Cmk-b between each distance measuring point on the recess surface and each distance measuring point on the basic surface adjacent to a recess, wherein mk denotes a recess numbered k on the digital surface m, and b denotes another number of the distance measuring point in the recess mk; step 1.5, using Cmk-b>K2 as a deep hole and Cmk-b>K3 as a through hole, wherein K2 denotes a preset deep hole determination threshold, and K3 denotes a model width, a model length or a model height corresponding to the surface n of the to-be-dried ceramic shell (4); step 1.6, counting positions Wmc of all deep holes in the digital surface m of the to-be-dried ceramic shell (4) and a depth Hmc corresponding to each deep hole, wherein c denotes a natural number of the deep hole in the digital surface m; step 1.7, repeating step 1.1 to step 1.6 until positions Wmc and depths Hmc of all the deep holes in a to-be-scanned surface of the to-be-dried ceramic shell (4) are counted, and determining an orientation Xmc of the deep hole according to the surface n where the deep hole is located; and step 1.8, outputting data of positions Wmc, depths Hmc and orientations Xmc of all deep holes in the surface of the to-be-dried ceramic shell (4).

8. The method for preparing a ceramic shell for precision casting according to claim 7, wherein in step 1.3, a method for acquiring the basic surface, the protruding surface and the recess surface comprises: step 1.3.1, acquiring the image data corresponding to the digital surface m of the to-be-dried ceramic shell (4), and splicing the image data so as to obtain an image surface R; step 1.3.2, performing element identification on the image surface R, and obtaining an element zone rn-m on the image surface R, wherein rn denotes a sequence number of the element zone in the digital surface m; step 1.3.3, adjusting the digital surface m to have a same orientation and a similar size to the image surface R; step 1.3.4, using an element zone rc-m having a maximum continuous area as the basic surface, wherein the rc-m belongs to rn-m; step 1.3.5, acquiring distance measuring point data of an element zone of each non-basic surface, wherein a distance measuring point of an element zone having a distance greater than that of a distance measuring point of an adjacent basic surface is a recess point, and a distance measuring point of an element zone having a distance smaller than that of the distance measuring point of the adjacent basic surface is a protruding point; and step 1.3.6, using the element zone as a boundary, and connecting adjacent recess point and protruding point to form the recess surface and the protruding surface.

9. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the three-dimensional detection mechanism (2) is provided with an electronic control telescopic device (205), and a tail end of a telescopic end of the electronic control telescopic device (205) is fixedly provided with a scanning device (207) through an electronic control pan-tilt (206); and the model structure analysis further comprises: step 2.1, controlling a scanning and distance measuring device (2073) to move to the position of the deep hole according to the position of the deep hole; step 2.2, acquiring depth measurement data of a plurality of deep holes by adjusting orientations of the scanning and distance measuring device (2073) relative to the deep holes; and step 2.3, correcting depth data Hm-c of an original deep hole with depth measurement data having a maximum depth, and obtaining corrected data Hm-c'.

10. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the scanning device (207) further comprises: an infrared temperature measuring device (2074); and the control system comprises: a drying process analysis module that acquires a measurement quantity of the infrared temperature measuring device (2074) for drying process analysis, so as to determine whether drying of the to-be-dried ceramic shell (4) is completed; and the drying process analysis comprises: measuring an internal temperature T of the deep hole regularly or continuously; and making a curve Qv of deep hole temperature TV-drying time t, wherein in response to determining that a curve segment conforming to a preset curve rule appears in Qv, it is indicated that drying of the to-be-dried ceramic shell (4) is completed; and v denotes a natural number of all the deep holes of the to-be-dried ceramic shell (4).

11. The method for preparing a ceramic shell for precision casting according to claim 10, wherein the preset curve rule is as follows: the internal temperature T of the deep hole gradually decreases from an initial drying temperature T1 to a temperature T2 with the drying time, and then gradually increases to a drying environment temperature T3 with the drying time, and in response to determining that the temperature T of the deep hole of the to-be-dried ceramic shell (4) changes from T1 to T2 and to T3 and is kept at the drying environment temperature T3 for preset time U, it is determined that drying is completed; and the initial drying temperature T1 is 22°C-26°C, the temperature T2 is 5°C-7°C lower than the temperature T1, and the drying environment temperature T3 is 24±1°C.

12. The method for preparing a ceramic shell for precision casting according to claim 11, wherein in response to determining that a plurality of to-be-dried ceramic shells (4) of a same batch are provided, temperatures of all the deep holes of all the to-be-dried ceramic shells (4) are measured one by one, and in response to determining that drying of more than L% of the to-be-dried ceramic shells (4) is completed, it is determined that drying of the entire batch of to-be-dried ceramic shells (4) is completed; and L%=(Lg-d) / (L0-d)*100%, wherein Lg-d denotes a number of to-be-dried ceramic shells (4) of a batch d after drying is completed, and L0-d denotes a number of all to-be-dried ceramic shells (4) of the batch d; a value of L% is: 100%≥L%≥E%; and E denotes a minimum preset percentage threshold of drying completion of all the to-be-dried ceramic shells (4) of the batch d.

13. The method for preparing a ceramic shell for precision casting according to claim 12, wherein the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells (4) having deep holes in surfaces, the following method is used: step 3.1, acquiring a total number D0 of all the deep holes of the to-be-dried ceramic shells (4), and acquiring a total number Dp of all the deep holes in the surfaces of the to-be-dried ceramic shells (4) faced by the fan sets p, wherein p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber (1); step 3.2, computing kS-p%=Dp / D0*100%, wherein kS-p% denotes control parameters of the fan sets p; and step 3.3, repeating step 3.1 to step 3.2 until kS-p% of all the fan sets is obtained; and in a case that all fan sets p face the to-be-dried ceramic shells (4) having no deep holes in surfaces, the following method is used: computing kF-p%=[1-D0 / (D0+1)]*100%, wherein kF-p% denotes control parameters of the fan sets p; and sending, by the fan set control module, obtained kS-p% and kF-p% of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full kS-p% or kF-p%.

14. The method for preparing a ceramic shell for precision casting according to claim 12, wherein the fan set control analysis is as follows: in a case that all fan sets p face the to-be-dried ceramic shells (4) having deep holes in surfaces, the following method is used: step 4.1, acquiring a total number D0 of all the deep holes of the to-be-dried ceramic shells (4), and acquiring a total number Dp of all the deep holes in the surfaces of the to-be-dried ceramic shells (4) faced by the fan sets p, wherein p denotes a number of the fan sets arranged at different sides in the vacuum drying chamber (1); step 4.2, acquiring kS-p% from a control parameter database according to the numbers of D0 and Dp, wherein the kS-p% denotes the control parameters of the fan sets p; and step 4.3, repeating step 4.1 to step 4.2 until kS-p% of all the fan sets is obtained; and in a case that all fan sets p face the to-be-dried ceramic shells (4) having no deep holes in surfaces, the following method is used: acquiring kF-p% from the control parameter database according to the total number D0 of all the deep holes of the to-be-dried ceramic shells (4), wherein the kF-p% denotes the control parameters of the fan sets p; and sending, by the fan set control module, obtained kS-p% and kF-p% of all the fan sets to the corresponding fan sets p, so as to control the fan sets p to run with full kS-p% or kF-p%.

15. The method for preparing a ceramic shell for precision casting according to claim 14, wherein a method for inputting kS-p% and kF-p% into the control parameter database comprises: step 5.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber (1) in a simulation apparatus; step 5.2, presetting a deep hole distribution of different to-be-dried ceramic shells (4) for drying training, and determining the control parameters kS-p% and kF-p% in a case that each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, wherein the deep hole distribution comprises: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells (4); and step 5.3, repeating step 5.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of D0-Dp-kS-p%-kF-p%, and storing the deep hole-control parameter relation set in the control parameter database.

16. The method for preparing a ceramic shell for precision casting according to claim 14 or 15, wherein at least two fans are arranged and mounted in the fan set; and the fan set control module synchronously or independently controls the fans in each fan set.

17. The method for preparing a ceramic shell for precision casting according to claim 16, wherein the fan set control analysis further comprises: step 6.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device (207); step 6.2, recording, by the scanning device (207), a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell (4) in a model structure analysis process; step 6.3, acquiring a coordinate system range Up-e covered by an air blowing orientation of each fan in the fan set p, wherein e denotes a natural number of the fans in the fan set p; step 6.4, counting a number Dup-e of deep holes in coverage Up-e and a number Dup of deep holes in entire coverage of the fan set p; and step 6.5, computing kup-e%=(Dup-e / Dup)*kS-p%, wherein the fan set control module sends obtained kup-e% of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full kup-e%; and the fan corresponding to Dup-e=0 runs at minimum power.

18. The method for preparing a ceramic shell for precision casting according to claim 16, wherein the fan set control analysis comprises: step 7.1, creating a three-dimensional coordinate system based on a scanning starting point preset by the scanning device (207); step 7.2, recording, by the scanning device (207), a three-dimensional coordinate point in a space in a displacement process, and performing three-dimensional coordinate point marking on the obtained position, orientation and depth of the deep hole of the to-be-dried ceramic shell (4) in a model structure analysis process; step 7.3, acquiring a coordinate system range Up-e covered by an air blowing orientation of each fan in the fan set p, wherein e denotes a natural number of the fans in the fan set p; step 7.4, counting a number Dup-e of deep holes in coverage Up-e and a number Dup of deep holes in entire coverage of the fan set p; and step 7.5, acquiring kup-e% of the corresponding fan from the control parameter database according to Dup and Dup-e, wherein the kup-e% denotes the control parameters of the fan numbered e in the fan set p, wherein the fan set control module sends obtained kup-e% of each fan in the fan set p to the corresponding fan, so as to control the corresponding fan to run with full kup-e%.

19. The method for preparing a ceramic shell for precision casting according to claim 18, wherein a method for inputting kup-e% into the control parameter database comprises: step 8.1, simulating a same position and orientation of the fan set as a target vacuum drying chamber (1) in a simulation apparatus; step 8.2, presetting a deep hole distribution of different to-be-dried ceramic shells (4) for drying training, and determining a running ratio kup-e% in a case that each fan in each fan set p corresponding to optimal drying time is relatively fully loaded under each deep hole distribution, wherein the deep hole distribution comprises: an orientation and a number of the deep holes; and the optimal drying time is minimum time for simultaneous drying of all the deep holes in the surfaces and surface layers of the to-be-dried ceramic shells (4); and step 8.3, repeating step 8.2 until training of the deep hole distribution under a normal condition is completed, creating a deep hole-control parameter relation set of Dup-Dup-e-kup-e%, and storing the deep hole-control parameter relation set in the control parameter database.

20. The method for preparing a ceramic shell for precision casting according to claim 14 or 18, wherein the vacuum rapid drying system comprises: a first data transmission module, a local database module, and a remote system module; the first data transmission module is connected to the remote system module through a signal line or is in signal connection with the remote system module in a wireless network connection manner; the local database module is used as the control parameter database, so as to store a related deep hole-control parameter relation set and running result data; the remote system module collects a deep hole-control parameter relation set and running result data of each vacuum rapid drying system through the first data transmission module, and selects the deep hole-control parameter relation set corresponding to an optimal running result from a same deep hole relation; and based on authorization and / or an instruction and / or automatic synchronization, the deep hole-control parameter relation set corresponding to the optimal running result is centralized through the remote system module, and then synchronized into the local database module of each vacuum rapid drying system through the first data transmission module, or is directly synchronized into the local database module of each vacuum rapid drying system through the first data transmission module; and in response to determining that the vacuum rapid drying system retrieves the deep hole-control parameter relation set in the local database module, and for instance, a new optimal deep hole-control parameter relation set exists, the new optimal deep hole-control parameter relation set is preferentially retrieved.

21. The method for preparing a ceramic shell for precision casting according to claim 20, wherein the vacuum rapid drying system further comprises a second data transmission module; the remote system module is connected to the control system of the vacuum rapid drying system by means of a signal line through the second data transmission module, or is in signal connection with the control system of the vacuum rapid drying system in a wireless network connection manner, so as to send a remote control instruction to the control system, and / or obtain a control instruction sent by the control system, and / or obtain running state parameters of all electronic control devices in the vacuum rapid drying system; and an execution priority of the remote control instruction sent by the remote system module is higher than that of the control instruction sent by the control system.

22. The method for preparing a ceramic shell for precision casting according to claim 1, wherein the scanning device (207) comprises: a thermal imager (2072); and a method for making the drying time of all the portions of the entire to-be-dried ceramic shell tend to be identical comprises: step 9.1, performing, by the thermal imager (2072), real-time thermal imaging photographing on the to-be-dried ceramic shell (4) along with the scanning device (207) in a drying process of the to-be-dried ceramic shell (4), and sending an image obtained through real-time thermal imaging photographing to the control system; and step 9.2, determining, by the control system, whether there is a zone T having a high-low temperature difference exceeding a preset temperature difference threshold according to a thermal imaging pattern in a case that the drying time exceeds preset first drying time according to a heat distribution in the thermal imaging pattern, and performing, in response to determining that there is the zone T, the following determination and operations: reducing, in response to determining that a low-temperature zone temperature of the zone T is lower than a preset low-temperature threshold, running power of the fan set corresponding to the zone T; enhancing, in response to determining that a high-temperature zone temperature of the zone T is higher than a preset high-temperature threshold, running power of the fan set corresponding to the zone T; and enhancing, in response to determining that time exceeds a preset time threshold in the zone T, the low-temperature zone temperature of the zone T is higher than a preset low-temperature threshold, and the high-temperature zone temperature of the zone T is lower than a preset high-temperature threshold, the running power of the fan set corresponding to the zone T.

23. The method for preparing a ceramic shell for precision casting according to claim 22, wherein the preset low-temperature threshold is 12°C-15°C, the preset high-temperature threshold is 26°C-28°C, the preset first drying time is 1 min-3 min, and the preset time threshold is 30 s-60 s.

24. The method for preparing a ceramic shell for precision casting according to claim 1, wherein a method for the vacuum rapid drying treatment is used and comprises: in a case that a surface layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 750 mmHg-720 mmHg within 5 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 750 mmHg-720 mmHg to the normal pressure within 5 s; and circulating the above process until drying of the surface layer is completed; in a case that a transition layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 720 mmHg-680 mmHg within 7 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell from 720 mmHg-680 mmHg to the normal pressure within 7 s; and circulating the above process until drying of the transition layer is completed; in a case that a supporting layer is dried, the method comprises the following steps: step 10.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 10.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 10.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-20 mmHg within 30 s; step 10.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 10.6, repeating step 10.4 and step 10.5 until drying of the supporting layer is completed; and in a case that a sealing layer is dried, firstly reducing an environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 120 mmHg-90 mmHg within 40 s; then restoring the environmental vacuum degree of the to-be-dried ceramic shell to the normal pressure within 120 s; and circulating the above process until drying of the sealing layer is completed.

25. The method for preparing a ceramic shell for precision casting according to claim 24, wherein at least three supporting layers are sequentially arranged from the transition layer to the sealing layer, wherein an inner surface of a first layer of the supporting layers is attached to an outer surface of the transition layer, and a method for performing a vacuum rapid drying treatment of the first layer of the supporting layers is used and comprises the following steps: step 11.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 11.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; step 11.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 260 mmHg-220 mmHg within 30 s; step 11.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and step 11.6, repeating step 11.4 and step 11.5 until drying of the first layer of the supporting layers is completed; an inner surface of a second layer of the supporting layers is attached to an outer surface of the first layer of the supporting layers, and a method for performing a vacuum rapid drying treatment of the second layer of the supporting layers is used and comprises the following steps: step 12.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 12.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; step 12.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 200 mmHg-150 mmHg within 30 s; step 12.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s; and step 12.6, repeating step 12.4 and step 12.5 until drying of the second layer of the supporting layers is completed; and an inner surface of a third layer of the supporting layers is attached to an outer surface of the second layer of the supporting layers, and a method for performing a vacuum rapid drying treatment of the third layer of the supporting layers is used and comprises the following steps: step 13.1, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min; step 13.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; step 13.4, reducing the environmental vacuum degree of the to-be-dried ceramic shell from normal pressure to 80 mmHg-20 mmHg within 30 s; step 13.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s; and step 13.6, repeating step 13.4 and step 13.5 until drying of the third layer of the supporting layers is completed, wherein an inner surface of the sealing layer is attached to an outer surface of the third layer of the supporting layers.

26. The method for preparing a ceramic shell for precision casting according to claim 2, wherein the vacuum rapid drying system further comprises: a vacuum tank (5); one end of the vacuum tank (5) is in communication with the vacuum pump (8) through a second connecting tube, and the second connecting tube is provided with a third electronic control valve (9); and the other end of the vacuum tank (5) is in communication with the vacuum drying chamber (1) through a third connecting tube (7), and the third connecting tube (7) is provided with a fourth electronic control valve (6).

27. The method for preparing a ceramic shell for precision casting according to claim 26, wherein a method for performing vacuum drying on the supporting layers and the sealing layer further comprises an instantaneous pressure reduction operation; and the instantaneous pressure reduction operation comprises: firstly closing the fourth electronic control valve (6) before pressure reduction, and performing pumping on the vacuum tank (5) to a low vacuum state in advance; then opening the fourth electronic control valve (6) during pressure reduction, such that the vacuum drying chamber (1) is in communication with the vacuum tank (5), and balanced low pressure is instantaneously dropped to within 0.5 s; and finally simultaneously extracting, by the vacuum pump (8), gas-phase components in the vacuum tank (5) and the vacuum drying chamber (1), closing the fourth electronic control valve (6) and the first electronic control switching valve (10) after a vacuum degree in the vacuum drying chamber (1) satisfies a preset target, and meanwhile, continuing to extract, by the vacuum pump (8), the gas-phase components in the vacuum tank (5) until the vacuum tank (5) is in the low vacuum state.

28. The method for preparing a ceramic shell for precision casting according to claim 27, wherein on the basis that the method for performing vacuum drying on the supporting layers and the sealing layer further comprises the instantaneous pressure reduction operation: a method for performing a vacuum rapid drying treatment of a first layer of the supporting layers is used and comprises the following steps: step 14.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 14.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank (5) continue to be vacuumized; step 14.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s; and making the vacuum tank (5) continue to be vacuumized; step 14.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 10 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 14.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 40 s, and making the vacuum tank (5) continue to be vacuumized; and step 14.6, repeating step 14.4 and step 14.5 until drying of the first layer of the supporting layers is completed; a method for performing a vacuum rapid drying treatment of a second layer of the supporting layers is used and comprises the following steps: step 15.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 15.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank (5) continue to be vacuumized; step 15.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s, and making the vacuum tank (5) continue to be vacuumized; step 15.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 200 mmHg-150 mmHg within 15 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 15.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 60 s, and making the vacuum tank (5) continue to be vacuumized; and step 15.6, repeating step 15.4 and step 15.5 until drying of the second layer of the supporting layers is completed; a method for performing a vacuum rapid drying treatment of a third layer of the supporting layers is used and comprises the following steps: step 16.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 16.2, keeping the environmental vacuum degree of the to-be-dried ceramic shell in a negative pressure state for 4 min-6 min, and making the vacuum tank (5) continue to be vacuumized; step 16.3, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s, and making the vacuum tank (5) continue to be vacuumized; step 16.4, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 80 mmHg-20 mmHg within 25 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 16.5, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 90 s, and making the vacuum tank (5) continue to be vacuumized; and step 16.6, repeating step 16.4 and step 16.5 until drying of the third layer of the supporting layers is completed; and a method for performing a vacuum rapid drying treatment of the sealing layer is used and comprises the following steps: step 17.1, performing the instantaneous pressure reduction operation, reducing an environmental vacuum degree of the to-be-dried ceramic shell from instantaneous balanced low pressure to 260 mmHg-220 mmHg within 35 s, and meanwhile, keeping the vacuum tank (5) vacuumized; step 17.2, restoring the environmental vacuum degree of the to-be-dried ceramic shell to normal pressure within 120 s, and making the vacuum tank (5) continue to be vacuumized; and step 17.3, repeating step 17.1 and step 17.2 until drying of the sealing layer is completed.

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