Binder jetting 3D printing device suitable for cylindrical products and working method thereof

Abstract

The present invention belongs to the field of 3D printing technology, and in particular, is a binder jet 3D printing device suitable for cylindrical products and a working method thereof, comprising a printing outer cylinder and a printing inner cylinder, the center of the printing outer cylinder is the same as that of the printing inner cylinder, a circular printing groove is formed between the printing outer cylinder and the printing inner cylinder, a printing powder spreading mechanism is arranged above the printing groove, and the printing powder spreading mechanism rotates clockwise or counterclockwise along the rotation axis. The present invention adopts an annular printing space, which greatly reduces the use of powder in non-model space, greatly improves the powder utilization rate on the one hand, and greatly reduces the invalid empty stroke on the other hand, greatly improves the printing efficiency. Compared with the existing 3D printing method, the number of expensive nozzles and the load-bearing capacity of the lifting platform are greatly reduced, thereby greatly reducing the equipment cost, which is of great significance for extending the service life of the equipment and improving the printing accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing, and in particular to a binder jetting 3D printing device suitable for cylindrical products and a working method thereof. Background Art

[0002] In the chemical and energy fields, there are many ceramic tubular parts with diameters and lengths ranging from several hundred millimeters to several thousand millimeters, especially wear-resistant linings, thermal insulation linings, reaction tanks, etc. made of ceramic materials such as silicon carbide and zirconium oxide. Although these parts are mainly simple cylindrical in shape, they are large in size and difficult to process using traditional mold forming, subtractive cutting or extrusion molding manufacturing processes.

[0003] Existing binder jet 3D printing equipment mainly adopts the XYZ space rectangular coordinate system layout, and the printing box is a rectangular parallelepiped or a cube and the height is generally not high. Therefore, when printing the above-mentioned large-diameter and high-height cylindrical parts, printing and cleaning powder are extremely inconvenient. If printing in the vertical direction, due to the insufficient height of the printing platform, a cylinder needs to be divided into multiple small cylinders for splicing, which not only affects the quality, but also increases the process, which is time-consuming and labor-intensive; and the cylinder model is arranged in a square printing platform. Due to the limitation of geometric relationships, there will be a large amount of powder inside the cylinder and around the square platform that does not participate in printing, so the space utilization rate and printing efficiency are extremely low. If printing is done in a flat manner, due to the large diameter of the cylinder, there will also be a large amount of powder inside the cylinder that does not participate in printing, so the space utilization rate and printing efficiency are also very low. The lying cylinder will form step patterns on the radial ring surface that are difficult to ignore due to the step effect of 3D printing, and the steps continue to change with the height, making it difficult to polish. Moreover, due to the anisotropic characteristics of 3D printing, the interlayer bonding defects that are most likely to occur in the vertical direction of the Z axis will be distributed along the radial direction of the model, which brings hidden dangers to the cylindrical structure, such as leakage and cracks. More importantly, when the flat cylinder is cleaning the powder inside and outside the cylinder, after the powder on the outside and inside of the lower half of the cylinder is cleared, the bottom of the lower half of the flat cylinder will be subjected to great pressure under the action of gravity, which can easily cause the cylinder to collapse or deform. Summary of the invention

[0004] In order to overcome the defects of the above-mentioned prior art, the present invention proposes a binder jet 3D printing device suitable for cylindrical products and its working method, which not only solves the problem of insufficient printing space in the vertical direction of cylindrical parts, but also solves the problem of difficult powder cleaning after printing of cylindrical parts, and avoids the problems such as step effect and collapse risk caused by printing in a flat manner; the present invention adopts an annular printing space, which greatly reduces the use of powder in non-model space, greatly improving the powder utilization rate on the one hand, and greatly reducing invalid empty strokes on the other hand, greatly improving printing efficiency. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] A binder jet 3D printing device suitable for cylindrical products comprises a printing outer cylinder and a printing inner cylinder, the centers of the printing outer cylinder and the printing inner cylinder are the same, a circular printing groove is formed between the printing outer cylinder and the printing inner cylinder, a printing powder spreading mechanism is arranged above the printing groove, and the printing powder spreading mechanism rotates clockwise or counterclockwise along the rotating axis; a printing base plate and a lifting base plate are arranged in the printing groove, an elongated hole is arranged on the printing inner cylinder, the lifting base plate is fixedly connected to a sleeve slider through a base plate connecting rod passing through the elongated hole, a lifting mechanism is arranged on the inner side of the printing inner cylinder, the lifting mechanism comprises a lifting screw and a sealing tape, and the sleeve slider is movably connected to the lifting screw; the sealing tape is arranged above the elongated hole, the sealing tape is fixedly connected to the inner wall of the printing inner cylinder through a roll frame, the extended end of the sealing tape bypasses the printing inner cylinder from above and is fixedly connected to the printing base plate along the outer wall of the printing inner cylinder, and the width of the sealing tape is greater than the width of the elongated hole.

[0006] Furthermore, the printing base plate is in a circular shape, the inner diameter of the printing base plate is 0.1mm-0.5mm larger than the inner diameter of the printing groove, the outer diameter of the printing base plate is 0.1mm-0.5mm smaller than the outer diameter of the printing groove, and the printing base plate and the printing outer cylinder and the printing inner cylinder are sealed by wool felt or sealing rubber.

[0007] Furthermore, a circular hanging base plate is placed above the printing base plate, the inner diameter of the hanging base plate is 0.1mm-5mm larger than the inner diameter of the printing base plate, and the outer diameter of the hanging base plate is 0.1mm-5mm smaller than the outer diameter of the printing base plate.

[0008] Furthermore, the elongated holes are arranged along the vertical direction, and there are at least two elongated holes.

[0009] Furthermore, the number of the bottom plate connecting rods, the sleeve sliders and the lifting mechanisms is consistent with the number of the long strip holes.

[0010] Specifically, the lifting mechanism also includes a lifting motor, which is connected to a lifting screw through a coupling. The lifting mechanism is arranged on a bracket, and the lifting screw is connected to the bracket through a lead screw nut. The bracket is fixedly connected to the base plate.

[0011] Specifically, the printing powder spreading mechanism includes a nozzle and a powder dropping trough, the nozzle is arranged on one side of the telescopic arm, and the powder dropping trough is arranged on the other side of the telescopic arm; a powder spreading scraper is arranged at the lower end of one side of the powder dropping trough, and the powder spreading scraper is arranged on the side of the powder dropping trough close to the nozzle, and a vibrator is arranged at the lower end of the other side of the powder dropping trough, and a powder upper limit detector and a powder lower limit detector are arranged above the vibrator, and the vibrator is driven by a vibration motor or compressed air; the telescopic arm is connected to the rotating arm through a telescopic guide rail, and the rotating arm is fixedly connected to the rotating shaft, and the rotating shaft is arranged at the center of the printing inner cylinder, and the rotation of the rotating shaft is driven by a motor.

[0012] Preferably, it further includes a powder replenishing mechanism, which includes a powder storage trough, a powder outlet movable plate is arranged at the lower end of the powder storage trough, an outlet vibrator is arranged on one side of the lower end of the powder storage trough, and an inclined vibrator is arranged on the other side of the lower end of the powder storage trough, and the powder storage trough is movably connected to the rotating sleeve through a movable bracket; a residual powder cylinder is arranged outside the printing outer cylinder, the rotating sleeve is fixedly connected to the outer wall of the residual powder cylinder, and the residual powder cylinder, the printing outer cylinder, and the printing inner cylinder are respectively fixedly connected to the base plate.

[0013] A working method of a binder jetting 3D printing device suitable for cylindrical products, when the printing system adopts a step-by-step printing method, comprises the following steps:

[0014] S200: The printing base plate drives the hoisting base plate to rise to the top;

[0015] S201: The printing base plate drives the lifting base plate to descend by one layer thickness, and the sealing tape descends along with the printing base plate and is pressed against the printing inner cylinder to seal the long strip hole. The printing powder spreading mechanism rotates clockwise or counterclockwise with the powder replenishing position as the starting point. At this time, the nozzle does not work, the powder dropping trough is dropping powder, and the powder spreading scraper is spreading powder;

[0016] S202: The printing powder spreading mechanism completes the spreading of a layer of powder by rotating one circle. When the printing powder spreading mechanism returns to the powder replenishing position again, it stops rotating and the powder dropping trough replenishes powder.

[0017] S203: Repeat steps S201 and S202 until the base powder is applied and the total thickness of the base powder is 20 times or more of the thickness of the printing layer. After the base powder is applied, execute S204;

[0018] S204: The printing base plate descends by one layer thickness, and the sealing tape descends along with the printing base plate and is pressed against the printing inner cylinder to seal the long strip hole. The printing powder spreading mechanism continues to rotate with the powder replenishing position as the starting point. At this time, the powder dropping trough drops powder, the powder spreading scraper spreads powder, and the nozzle sprays the adhesive.

[0019] S205: The printing powder spreading mechanism rotates one circle to complete the spreading of a layer of powder and the sprayed binder forms a slice layer on the current layer of the model. When the printing powder spreading mechanism returns to the powder replenishing position again, it stops rotating, the nozzle stops spraying the binder, the powder drop trough replenishes powder, and the nozzle inkjet information is changed to the next slice layer of the model;

[0020] S206: Repeat steps S204 and S205 until the powdering and adhesive spraying of all model slice layers are completed.

[0021] A working method of a binder jet 3D printing device suitable for cylindrical products, when the printing system adopts a continuous printing method, comprises the following steps:

[0022] S300: The printing base plate drives the hoisting base plate to rise to the top;

[0023] S301: The printing powder spreading mechanism rotates clockwise or counterclockwise at a constant speed with the powder replenishing position as the starting point, and the printing base plate drives the hoisting base plate to descend at a constant speed. The time for the printing powder spreading mechanism to rotate one circle at a constant speed is equal to the time for the printing base plate to descend at a constant speed by one layer, that is, the printing base plate descends at a constant speed while spreading powder. At this time, the nozzle does not work, the powder dropping trough is dropping powder, the powder spreading scraper is spreading powder, and the sealing tape descends with the printing base plate and is close to the printing inner cylinder to form a seal for the long strip hole;

[0024] S302: maintaining the rotation speed and the descending speed, and replenishing the powder in the powder drop chute during the time period of passing through the powder replenishing mechanism;

[0025] S303: Repeat steps S301 and S302 until the base powder is applied and the total thickness of the base powder is 20 times or more of the thickness of the printing layer. After the base powder is applied, execute S304;

[0026] S304: maintaining the rotation speed and the descending speed, the powder dropping trough drops powder, the powder spreading scraper spreads powder, and the nozzle sprays the binder;

[0027] S305: When the printing powder spreading mechanism returns to the powder replenishing position again, a layer of powder is spread and the sprayed binder forms a slice layer on the current layer of the model, and the inkjet information of the nozzle is changed to the next slice layer of the model;

[0028] S306: Repeat steps S304 and S305 until the powdering and adhesive spraying of all model slice layers are completed.

[0029] The present invention adopts an annular printing space, which greatly reduces the use of powder in non-model space. On the one hand, it greatly improves the powder utilization rate, and on the other hand, it greatly reduces the invalid empty stroke, greatly improving the printing efficiency. Compared with the existing 3D printing method, the number of expensive nozzles and the load-bearing capacity of the lifting platform are greatly reduced, thereby greatly reducing the equipment cost. The present invention not only solves the problem of insufficient printing space in the vertical direction for cylindrical parts, but also solves the problem of difficulty in clearing powder after printing cylindrical parts, and avoids the problems of step effect and collapse risk caused by printing in a lying manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of the printing device of the present invention;

[0031] Figure 2 for Figure 1 A top view of

[0032] Figure 3 It is a top view of the lifting base plate;

[0033] Figure 4 This is a schematic diagram of the initial state of powder spreading;

[0034] Figure 5 This is a schematic diagram of the powder spreading end state;

[0035] Figure 6 It is a structural diagram of the printing powder spreading mechanism;

[0036] Figure 7 This is a schematic diagram of the printing powder laying process;

[0037] Figure 8 It is a schematic diagram of the powder cleaning state;

[0038] Fig. 9 is a schematic diagram of the control system;

[0039] Fig.10 is a flow chart of a step-by-step printing method;

[0040] Fig.11 is a flow chart of a continuous printing method;

[0041] Fig.12 This is the flow chart for powder cleaning. DETAILED DESCRIPTION

[0042] Combination Figures 1 to 8 As shown, the entire printing device is divided into the following mechanisms or parts according to its functions: a cylindrical printing bin mechanism 10, a lifting mechanism 20, a rotary motion mechanism 30, a printing powder spreading mechanism 40, powder 50, a powder replenishing mechanism 60, and a hoisting mechanism 70.

[0043] A binder jet 3D printing device suitable for cylindrical products comprises a printing outer cylinder 12 and a printing inner cylinder 13, wherein the centers of the printing outer cylinder 12 and the printing inner cylinder 13 are the same, and a circular printing groove is formed between the printing outer cylinder 12 and the printing inner cylinder 13, and a printing powder spreading mechanism 40 is arranged above the printing groove, and the printing powder spreading mechanism 40 rotates clockwise or counterclockwise along the rotation axis; a printing bottom plate 21 and a lifting bottom plate 22 are arranged in the printing groove, and a long strip hole 17 is arranged on the printing inner cylinder 13, and the lifting bottom plate 22 is fixedly connected with a sleeve slider 22.2 through a bottom plate connecting rod 22.1 passing through the long strip hole 17 Next, a lifting mechanism 20 is arranged on the inner side of the printing inner cylinder 13, and the lifting mechanism 20 includes a lifting screw 23 and a sealing tape 27, and the sleeve slider 22.2 is movably connected to the lifting screw 23; the sealing tape 27 is arranged above the elongated hole 17, and the sealing tape 27 is fixedly connected to the inner wall of the printing inner cylinder 13 through the roll frame 28, and the protruding end of the sealing tape 27 bypasses the printing inner cylinder 13 from above and is fixedly connected to the printing base plate 21 along the outer wall of the printing inner cylinder 13, and the width of the sealing tape 27 is greater than the width of the elongated hole 17, and the sealing tape 27 is used to seal the elongated hole 17 to prevent powder leakage.

[0044] The lifting mechanism 20 also includes a lifting motor 25, which is connected to the lifting screw 23 through a coupling 24. The sleeve slider 22.2 is sleeved on the lifting screw 23. The sleeve slider 22.2 can move along the lifting direction 26 on the lifting screw 23. The lifting mechanism 20 is set on the bracket 14. The lifting screw 23 is connected to the bracket 14 through a screw nut, and the bracket 14 is fixedly connected to the base plate 16.

[0045] A powder blocking plate 15 is provided above the bracket 14 , the inner side of the powder blocking plate 15 is fixedly connected to the bracket 14 , and the length of the powder blocking plate 15 is equivalent to the diameter of the printing inner cylinder 13 to prevent printing powder from falling onto the lifting mechanism 20 .

[0046] The long strip holes 17 are arranged in the vertical direction, and there are at least two long strip holes 17. The number of the bottom plate connecting rods 22.1, the sleeve sliders 22.2 and the lifting mechanism 20 is consistent with the number of the long strip holes 17. In this embodiment, the length of the long strip holes 17 is 2.2m, and there are 4 long strip holes 17. Figure 3 As shown, there are four bottom plate connecting rods 22.1, four sleeve sliders 22.2, and four sets of lifting mechanisms 20, that is, four sets of lifting screws 23, sealing tapes 27, lifting motors 25, couplings 24, and reel racks 28.

[0047] The printing powder spreading mechanism 40 includes a nozzle 46 and a powder dropping trough 41, the nozzle 46 is arranged on one side of the telescopic arm 35, the powder dropping trough 41 is arranged on the other side of the telescopic arm 35, a powder spreading scraper 45 is arranged at the lower end of one side of the powder dropping trough 41, the powder spreading scraper 45 is arranged on the side of the powder dropping trough 41 close to the nozzle 46, a vibrator 44 is arranged at the lower end of the other side of the powder dropping trough 41, a powder upper limit detector 42 and a powder lower limit detector 43 are arranged above the vibrator 44, and the vibrator 44 is driven by a vibration motor or compressed air (not shown in the figure).

[0048] A telescopic guide rail 34 is installed above the rotating arm 33, and the telescopic arm 35 is connected to the rotating arm 33 through the telescopic guide rail 34. The rotating arm 33 is fixedly connected to the rotating shaft 32. The rotating shaft 32 is arranged at the center of the printing inner cylinder 13. The rotating shaft 32 is installed above the base 31 and provides rotational power to the rotating arm 33 to move along the rotation direction 36. The rotation of the rotating shaft 32 is driven by a first motor (not shown in the figure), and the telescopic arm 35 is driven by a second motor (not shown in the figure); a printing powder spreading mechanism 40 is installed at the end of the telescopic arm 35, and the working space of the printing powder spreading mechanism 40 is adjusted by adjusting the position of the telescopic arm 35 on the telescopic guide rail 34.

[0049] The powder upper limit detector 42 is used to provide a signal of sufficient powder replenishment, and the powder lower limit detector 43 is used to detect a signal of insufficient powder in the powder drop trough 41. The vibrator 44 is installed at the outlet of the powder drop trough 41. The vibrator 44 can control the fluidity of the powder by adjusting the vibration frequency and amplitude, thereby roughly controlling the powder in front of the powder scraper 45. The nozzle 46 can spray the adhesive 47 to form a bonding shape for the powder.

[0050] It also includes a powder replenishing mechanism 60, which includes a powder storage groove 62, a powder outlet movable plate 65 is arranged at the lower end of the powder storage groove 62, an outlet vibrator 63 is arranged on one side of the lower end of the powder storage groove 62, and an inclined vibrator 64 is arranged on the other side of the lower end of the powder storage groove 62. The powder storage groove 62 is movably connected to the rotating sleeve 67 through a movable bracket 61; a residual powder cylinder 11 is arranged outside the printing outer cylinder 12, and a residual powder groove is formed between the residual powder cylinder 11 and the printing outer cylinder 12, and the rotating sleeve 67 is fixedly connected to the outer wall of the residual powder cylinder 11, the upper end of the movable bracket 61 is fixedly connected to the powder storage groove 62, and the lower end is inserted into the rotating sleeve 67, which can rotate along the rotation direction 66, and the residual powder cylinder 11, the printing outer cylinder 12, and the printing inner cylinder 13 are respectively fixedly connected to the base plate 16.

[0051] The hanging base plate 71 is placed above the printing base plate 21 to support the powder and the printing model. The hanging ring 72 is fixed to the hanging base plate 71 during the powder cleaning stage, and the hanging belt 73 and the hanging hook 74 are connected and installed accordingly.

[0052] The powder 50 is temporarily stored in the powder storage tank 62 as powder 51, and becomes powder falling powder 52 when transferred to the powder dropping mechanism. After being spread by a scraper, it is compacted and flattened on the printing platform to form powder spreading powder 53. The part selectively bonded by the adhesive 47 is bonding powder 54, and the excess overflowed powder is temporarily stored in the residual powder tank to form residual powder 55.

[0053] The printing base plate 21 is in the shape of a ring, the inner diameter of the printing base plate 21 is 0.1mm-0.5mm larger than the inner diameter of the printing tank, the outer diameter of the printing base plate 21 is 0.1mm-0.5mm smaller than the outer diameter of the printing tank, and the printing base plate 21 is sealed with the printing outer cylinder 12 and the printing inner cylinder 13 by wool felt or sealing rubber. A ring-shaped hanging base plate 71 is placed above the printing base plate 21, the inner diameter of the hanging base plate 71 is 0.1mm-5mm larger than the inner diameter of the printing base plate 21, and the outer diameter of the hanging base plate 71 is 0.1mm-5mm smaller than the outer diameter of the printing base plate 21. When the printing base plate 21 rises to the highest point, the upper surface of the hanging base plate 71 is 0-3mm lower than the upper surface of the printing tank.

[0054] The printing base plate 21 is arranged between the printing outer cylinder 12 and the printing inner cylinder 13, and serves as a base plate for supporting powder and printing models; the bottoms of the printing outer cylinder 12 and the printing inner cylinder 13 of this embodiment are respectively connected to the base plate by detachable pins and screws.

[0055] The length of the sealing tape 27 of the present invention exceeds the length of the long strip hole 17, and since the width of the sealing tape 27 is much larger than the long strip hole 17, the sealing tape 27 will be evenly compressed by the surrounding powder when in use, so no bulge will be formed towards the long strip hole 17; the protruding end of the sealing tape 27 is fixed to the printing base plate 21, so that as the printing platform descends, the sealing tape 27 can be gradually pulled downward, and the long strip hole 17 can be sealed under the pressure of the powder.

[0056] The lifting mechanism 20 of the present invention is arranged inside the printing inner cylinder 13 and does not need to be arranged below the printing inner cylinder 13. Therefore, the overall height of the equipment is much lower than that of the existing binder jet 3D printing equipment, which solves the problem of insufficient printing space for cylindrical parts in the vertical direction; wherein, the elongated hole 17 and the sealing tape 27 play an important role: the elongated hole 17 serves as a channel for moving up and down, and the sealing tape prevents powder from leaking out of the hole to avoid affecting the internal structure of the equipment, while ensuring the sealing of the printing environment, which is conducive to improving printing accuracy.

[0057] The present invention adopts a polar coordinate system structure to replace the existing XYZ rectangular coordinate system structure, adopts a circular ring as a printing platform, and the printing nozzle 46 and the powder spreading mechanism are installed on the same telescopic arm 35 as a printing mechanism. The telescopic arm 35 is installed on a rotating swing arm, and the telescopic arm 35 can translate on the slide rail, so it is suitable for printing cylindrical parts of different sizes. The present invention can change the size of the cylinder and the platform according to actual needs, and adjust the elongation of the telescopic arm 35, so as to adapt to the manufacturing of products of different sizes.

[0058] The printing outer cylinder and the printing inner cylinder of the present invention are arranged concentrically, and the annular printing groove formed between the two is the main space for printing cylindrical products. This annular printing space is different from the traditional rectangular printing space, and is more in line with the shape characteristics of cylindrical products, laying a foundation for subsequent efficient printing.

[0059] The printing powder spreading mechanism located above the printing tank can rotate clockwise or counterclockwise along the rotation axis. During the printing process, it is responsible for spreading the powder evenly in the printing tank, ensuring that the thickness and uniformity of each layer of powder meet the printing requirements, thereby providing a good foundation for the injection of the binder and the molding of the model. The printing base plate set in the printing tank is the starting plane for the printing of cylindrical products, providing bottom support for the printed model, ensuring the stability of the printing process and the bottom quality of the model.

[0060] Compared with existing 3D printing methods, this binder jet 3D printing device for cylindrical products has significant advantages in many aspects. First, due to the use of an annular printing space, there is no need to use a large number of nozzles to cover the entire printing area like the traditional rectangular printing space, which greatly reduces the number of expensive nozzles and reduces the hardware cost of the equipment. Secondly, the annular printing groove makes the load-bearing of the lifting platform more uniform, and because the weight of the powder in the non-model space is reduced, the load-bearing requirements of the lifting platform are further reduced, which is of great significance for extending the service life of the equipment and improving printing accuracy.

[0061] The present invention also includes a control system, such as Fig. 9As shown, the control system 100 includes a processor 110 and a memory 120, and the control system 100 is respectively connected to the cylindrical printing bin mechanism 10, the lifting mechanism 20, the rotating motion mechanism 30, the printing powder spreading mechanism 40 and the powder replenishing mechanism 60. The processor 110 includes a controller 111 and an operator 112, which are used to provide calculations for the control parameters of the actuator; the parameter settings 121 of the memory 120 include the control parameters, process parameters and equipment component information preset in the printing software, and the control instructions 122 of the memory 120 are instructions stored in advance, or new instructions calculated after obtaining information through the operator 112 and the controller 111. In the entire printing device control system, the input data includes the parameter settings from the printing software, the parameter settings of the controller, the model slicing information provided by the slicing software, and the sensor information of the device actuator. The output data is the control parameters of each actuator and the data display of the printing software display interface.

[0062] In order to be suitable for printing equipment that produces cylindrical parts with a small diameter range, the following parts can be replaced with new sizes: residual powder cylinder 11, printing outer cylinder 12, printing inner cylinder 13, powder baffle 15, long strip hole 17, printing base plate 21, lifting base plate 22 and hanging base plate 71; through these changes, while retaining other mechanisms or parts, combined with the length adjustment of the telescopic arm 35, it is more suitable for printing cylindrical parts with a small diameter range.

[0063] The printing powder of the present invention can be polymer powder, metal powder, or other inorganic non-metal powder, including silicon carbide, zirconium oxide, aluminum oxide, kaolin, silicate, quartz, and graphite.

[0064] The printing powder of the present invention is suitable for powder materials with a repose angle between 35° and 48°. The powder passing through the powder replenishing port and the powder dropping port can obtain sufficient fluidity under the vibration motor, and the powder outflow will not be uncontrollable due to excessive fluidity.

[0065] The adhesive of the present invention can be a two-component or multi-component adhesive or a single-component adhesive; it can also be an aqueous or oily adhesive, a water-based or alcohol-based adhesive; it can also be an organic or inorganic adhesive, and it can also be an adhesive of the type of drying, heat curing, chemical reaction curing, or UV curing.

[0066] The invention is suitable for cylindrical products with inner diameters ranging from 500 mm to 5000 mm and heights ranging from 1 mm to 3000 mm. The thickness of the cylindrical products can be adapted by increasing the number of side-by-side nozzles.

[0067] The design capacity of the residual powder tank of the present invention should be greater than half of the amount of powder involved in printing.

[0068] The lifting base plate of the present invention can be driven by a lead screw and a lead screw nut, a linear slider and a synchronous belt, or a linear motor module, and the number of linear motors can be 2-6 depending on the size of the load.

[0069] The number of nozzles in the printing and powder spreading mechanism of the present invention can be one or more.

[0070] In the printing powder spreading mechanism of the present invention, the bottom of the scraper has a smooth surface, which avoids generating greater friction during rotation, and can compact the powder while avoiding horizontal shear displacement of the powder, thereby avoiding problems such as pushing the powder.

[0071] The amplitude and vibration frequency of the powder outlet vibrator of the present invention can be adjusted by the eccentricity or rotation speed of the eccentric wheel. The vibrator can be an eccentric wheel vibration motor, a pneumatic vibrator, an ultrasonic vibrator, etc.

[0072] The powder replenishing amount of the powder replenishing mechanism of the present invention can be adjusted by the working frequency and amplitude of the powder outlet vibrator, and can also be changed by adjusting the opening size of the powder outlet moving plate.

[0073] The height of the base powder of the present invention is usually 10-100 times the thickness of the powder layer. The particle size corresponding to the cumulative particle size distribution of the powder sample reaches 50%, also called the median diameter or median particle size, i.e. D50. The printing layer thickness is usually more than 2 times the powder particle size D50 to achieve a uniform powder density.

[0074] The amount of powder added each time in the present invention is 0.5-2 times the amount required for each layer of powder spreading, which is specifically determined by the distance between the upper and lower limit sensors of the powder. When the powder spreading is completed, the remaining powder that does not participate in the powder spreading should fall into the remaining powder groove under the guidance of the scraper and the centrifugal force, so as to avoid cumulative errors in the next powder adding and powder spreading process.

[0075] The linear speed of the nozzle and the scraper of the present invention is within the range of 50 mm to 500 mm, and the linear speed is changed by changing the rotation speed of the rotating arm.

[0076] The falling powder of the present invention should have sufficient fluidity under the action of the vibrator and flow to the front of the scraper under the action of gravity, but at the same time the fluidity should not be too good to cause the powder to flow out quickly, and the powder should be maintained accumulated in a limited range in front of the scraper.

[0077] The dimensions of the telescopic guide rail and the telescopic arm of the present invention need to be determined according to the diameters of the largest and smallest printing models.

[0078] The present invention only needs to spread powder and spray binder in the annular printing space, so the powder utilization rate is very high and the powder cleaning work is convenient; the design of the replaceable cylinder printing platform and the retractable printing mechanism can adapt to the batch production of cylinder products of different sizes. The continuous spiral printing method is adopted, and there is no powder replenishment and lifting waiting process, which greatly improves the printing efficiency; during the printing process, the main power of the equipment is only lifting and rotation, and the main components are simple cylinder structures, and one or two nozzles can be used to realize the printing of large-sized cylinders, which greatly reduces the equipment cost.

[0079] like Fig.10 As shown, a working method of a binder jet 3D printing device suitable for cylindrical products, when the printing system adopts a step-by-step printing method, includes the following steps:

[0080] S200: The lifting motor 25 drives the lifting screw 23 to rotate through the coupling 24, thereby driving the lifting base plate 22, the printing base plate 21 and the hanging base plate 71 to rise, so that the hanging base plate 71 rises to the top, and the telescopic arm 35 extends along the telescopic guide rail 34 to the top of the printing base plate 21.

[0081] S201: The lifting motor 25 drives the lifting screw 23 to rotate through the coupling 24, thereby driving the lifting base plate 22, the printing base plate 21 and the hanging base plate 71 to descend by one layer thickness. The printing powder spreading mechanism rotates clockwise or counterclockwise with the powder replenishing position as the starting point according to the installation sequence of the powder dropping trough 41 and the powder spreading scraper 45. The initial state is shown in FIG. Figure 3 As shown, at this time, the nozzle 46 is not working, the powder dropping groove 41 is dropping powder, and the powder spreading scraper 45 is spreading powder, that is, the powder spreading scraper 45 scrapes the falling powder flat.

[0082] In this process, since the lifting base plate 22 drives the printing base plate 21 to move in the vertical direction, it needs to pass through the long strip hole 17 on the printing inner cylinder 13, and the sealing tape 27 will be pulled out and descend together with the printing base plate 21. During the descent process, the sealing tape 27 will be close to the printing inner cylinder 13 under the action of the powder pressure, and form a seal on the long strip hole 17 to prevent powder leakage.

[0083] S202: The printing powder spreading mechanism completes the spreading of a layer of powder after one rotation. When the printing powder spreading mechanism returns to the powder replenishing position, it stops rotating and the powder dropping trough 41 replenishes powder. Whether to replenish powder is determined based on whether the powder lower limit detector 43 is stimulated. If the powder height is lower than the detection point of the powder lower limit detector 43, powder replenishment is required.

[0084] When replenishing powder, the powder outlet movable plate 65 moves to the right, and the temporarily stored powder 51 is gradually filled into the powder falling groove 41 under the action of its own weight. The amount of powder replenished per unit time can be adjusted by the outlet vibrator 63, the vibration frequency and amplitude, and the moving distance of the powder outlet movable plate 65. During this process, the inclined vibrator 64 maintains vibration to ensure that the powder on the left side of the powder storage groove 62 will not be difficult to flow due to the problem of the stacking angle.

[0085] S203: Repeat steps S201 and S202 until the base powder is applied. The total thickness of the base powder is 20 times or more of the print layer thickness. See the completion status. Figure 4 As shown, after the base powder is applied, S204 is executed.

[0086] S204: The printing base plate 21 descends by one layer thickness, and the sealing tape 27 descends along with the printing base plate 21 and is pressed against the printing inner cylinder 13 to seal the long strip hole 17. The printing powder spreading mechanism continues to rotate with the powder replenishing position as the starting point. At this time, the powder dropping trough 41 drops powder, the powder spreading scraper 45 spreads powder, and the nozzle 46 sprays the adhesive.

[0087] S205: The printing powder spreading mechanism rotates one circle to complete the spreading of a layer of powder and the sprayed binder forms a slice layer on the current layer of the model. When the printing powder spreading mechanism returns to the powder replenishing position again, it stops rotating, the nozzle 46 stops spraying the binder, the powder drop groove 41 replenishes powder, and the nozzle inkjet information is changed to the next slice layer of the model. The binder of the present invention is also called ink.

[0088] S206: Repeat steps S204 and S205 until the powdering and adhesive spraying of all model slice layers are completed.

[0089] See also Figure 7 As shown, the second layer printing is performed. At this time, the first layer of powder 53 will contact and be compacted with the new layer of powder 53 to form a bonding powder 54, and the first layer of bonding powder 54 and each subsequent layer of bonding powder 54 will contact and bond together, and finally complete the printing of the entire cylindrical 3D model by stacking layer by layer.

[0090] like Fig.11 As shown, a working method of a binder jet 3D printing device suitable for cylindrical products, when the printing system adopts a continuous printing method, includes the following steps:

[0091] S300: The lifting motor 25 drives the lifting screw 23 to rotate through the coupling 24, thereby driving the lifting base plate 22, the printing base plate 21 and the hanging base plate 71 to rise, so that the hanging base plate 71 rises to the top.

[0092] S301: The printing powder spreading mechanism rotates clockwise or counterclockwise at a constant speed with the powder replenishing position as the starting point, and the printing base plate 21 drives the lifting base plate 71 to descend at a constant speed, and the time for the printing powder spreading mechanism to rotate one circle at a constant speed is equal to the time for the printing base plate 21 to descend one layer at a constant speed, that is, the printing base plate 21 descends at a constant speed while spreading powder. At this time, the nozzle 46 does not work, the powder dropping trough 41 is dropping powder, and the powder spreading scraper 45 is spreading powder, that is, the powder spreading scraper 45 scrapes the fallen powder flat, although the scraped powder layer is spirally rising, because the thickness of each layer is very small, the impact can be ignored relative to the size of the entire product; the sealing roll 27 descends with the printing base plate 21, and is close to the printing inner cylinder 13 to form a seal for the long strip hole 17.

[0093] S302: The rotation speed and the descending speed are maintained, and the powder dropping chute 41 is replenished with powder during the time period of the powder replenishing mechanism.

[0094] S303: Repeat steps S301 and S302 until the base powder is applied and the total thickness of the base powder is 20 times or more of the thickness of the printing layer. After the base powder is applied, execute S304.

[0095] S304: Maintain the rotation speed and the descending speed, see Figure 7 As shown, the powder dropping trough 41 drops powder, the powder spreading scraper 45 spreads powder, and the nozzle 46 sprays the adhesive.

[0096] S305: When the printing powder spreading mechanism returns to the powder replenishing position again, a layer of powder is spread and the sprayed binder forms a slice layer on the current layer of the model, and the inkjet information of the nozzle is changed to the next slice layer of the model.

[0097] S306: Repeat steps S304 and S305 until the powdering and adhesive spraying of all model slice layers are completed.

[0098] During printing, the printing powder spreading mechanism rotates under the drive of the rotating shaft, and evenly spreads the powder from the powder dropping groove onto the printing base plate in the printing groove, forming a thin powder layer. As the powder spreading mechanism continues to rotate, the powder can be more evenly distributed in the printing groove under the combined action of centrifugal force and gravity, preparing for subsequent binder spraying.

[0099] When the powder layer is laid, the nozzle will accurately spray the binder to the corresponding position on the powder layer according to the preset model data. Due to the use of an annular printing space, the nozzle's spray path is relatively more concentrated and regular, ensuring the full combination of the binder and the powder, and improving the molding quality of the model; at the same time, the annular printing space also enables the nozzle to completely cover the entire printing area during the spraying process. The nozzle only needs to rotate and does not need to move radially along the diameter, which reduces unnecessary empty strokes and improves spraying efficiency.

[0100] The powder sprayed with the binder solidifies quickly under the action of the binder to form a model layer with a certain strength. Then, the printing powder spreading mechanism continues to rotate and spread the powder, and the nozzle sprays the binder again, and this is repeated, layer by layer, until the entire cylindrical product model is printed. In this process, since the annular printing space reduces the use of powder in the non-model space, it not only improves the powder utilization rate and reduces the material cost, but also reduces the invalid empty stroke, greatly shortens the printing time, and improves the printing efficiency.

[0101] Combination Figure 8 and Fig.12 As shown, let it stand for 2-12 hours before cleaning the powder until the green body sprayed with the binder hardens, and then clean the powder.

[0102] S400 : the lifting mechanism 20 and the rotating mechanism 30 stop, the printing powder spreading mechanism 40 retracts to a minimum length along the telescopic guide rail 34 , and then the powder replenishing mechanism 60 rotates to the outside along the rotating direction 66 .

[0103] S401: The printing base plate 21 rises to a height of 100-500 times the layer thickness, and the powder inside and outside the printed body is manually cleaned. At this time, due to the effect of gravity, the solidified bonding powder 54 is maintained on the printing base plate 21, and the loose powder 53 on the outside falls into the residual powder groove and mixes with the residual powder 55, while the loose powder on the inside falls above the powder blocking plate 15. The powder here needs to be cleaned in time with a vacuum powder extractor or a vacuum cleaner.

[0104] S402: Repeat step S401 until the hoisting bottom plate 71 is exposed, clean out the hoisting screw holes, and recycle the powder collected on the powder blocking plate 15 together with the residual powder 55.

[0105] S403: The installation ring 72 is fixed to the lifting base plate 71, and the lifting belt 73 and the hook 74 are connected and installed accordingly. Finally, the printed body is taken out by lifting to perform necessary post-processing work, and all printing work is completed.

[0106] In short, the present invention adopts an annular printing space, which greatly reduces the use of powder in non-model space. On the one hand, it greatly improves the powder utilization rate, and on the other hand, it greatly reduces the invalid empty stroke, greatly improving the printing efficiency. Compared with the existing 3D printing method, the number of expensive nozzles and the load-bearing capacity of the lifting platform are greatly reduced, thereby greatly reducing the equipment cost, which is of great significance for extending the service life of the equipment and improving the printing accuracy. The present invention not only solves the problem of insufficient printing space in the vertical direction of cylindrical parts, but also solves the problem of difficulty in cleaning powder after printing of cylindrical parts, and avoids the step effect and collapse risk caused by printing in a lying manner. By replacing printing platforms and printing cylinders of different sizes, and correspondingly changing the length of the telescopic arm and the number of nozzles, the manufacture of cylindrical parts of different sizes can be realized on the same printing equipment, which is particularly suitable for 3D printing of cylindrical parts with large diameters and high heights.

Claims

1. A binder jet 3D printing device suitable for cylindrical products, characterized in that: The printing machine comprises a printing outer cylinder and a printing inner cylinder, wherein the centers of the printing outer cylinder and the printing inner cylinder are the same, and a circular printing groove is formed between the printing outer cylinder and the printing inner cylinder, and a printing powder spreading mechanism is arranged above the printing groove, and the printing powder spreading mechanism rotates clockwise or counterclockwise along the rotating shaft; a printing base plate and a lifting base plate are arranged in the printing groove, and an elongated hole is arranged on the printing inner cylinder, and the lifting base plate is fixedly connected to the sleeve slider through a base plate connecting rod passing through the elongated hole, and a lifting mechanism is arranged on the inner side of the printing inner cylinder, and the lifting mechanism comprises a lifting screw and a sealing tape, and the sleeve slider is movably connected to the lifting screw; the sealing tape is arranged above the elongated hole, and the sealing tape is fixedly connected to the inner wall of the printing inner cylinder through a roll frame, and the extended end of the sealing tape bypasses the printing inner cylinder from above and is fixedly connected to the printing base plate along the outer wall of the printing inner cylinder, and the width of the sealing tape is greater than the width of the elongated hole.

2. The binder jetting 3D printing device for cylindrical products according to claim 1, characterized in that: The printing powder spreading mechanism includes a nozzle and a powder dropping trough, the nozzle is arranged on one side of the telescopic arm, and the powder dropping trough is arranged on the other side of the telescopic arm; a powder spreading scraper is arranged at the lower end of one side of the powder dropping trough, and the powder spreading scraper is arranged on the side of the powder dropping trough close to the nozzle, a vibrator is arranged at the lower end of the other side of the powder dropping trough, and a powder upper limit detector and a powder lower limit detector are arranged above the vibrator, and the vibrator is driven by a vibration motor or compressed air; the telescopic arm is connected to the rotating arm through a telescopic guide rail, the rotating arm is fixedly connected to the rotating shaft, the rotating shaft is arranged at the center of the printing inner cylinder, and the rotation of the rotating shaft is driven by a motor.

3. The binder jetting 3D printing device for cylindrical products according to claim 2, characterized in that: It also includes a powder replenishing mechanism, which includes a powder storage trough, a powder outlet movable plate is arranged at the lower end of the powder storage trough, an outlet vibrator is arranged on one side of the lower end of the powder storage trough, and an inclined vibrator is arranged on the other side of the lower end of the powder storage trough, and the powder storage trough is movably connected to the rotating sleeve through a movable bracket; a residual powder cylinder is arranged outside the printing outer cylinder, the rotating sleeve is fixedly connected to the outer wall of the residual powder cylinder, and the residual powder cylinder, the printing outer cylinder, and the printing inner cylinder are respectively fixedly connected to the base plate.

4. The binder jetting 3D printing device for cylindrical products according to claim 3, characterized in that A circular hoisting base plate is placed above the printing base plate, the inner diameter of the circular hoisting base plate is 0.1mm-5mm larger than the inner diameter of the printing base plate, and the outer diameter of the circular hoisting base plate is 0.1mm-5mm smaller than the outer diameter of the printing base plate.

5. The binder jetting 3D printing device for cylindrical products according to claim 1, characterized in that: The printing base plate is in a circular shape, the inner diameter of the printing base plate is 0.1mm-0.5mm larger than the inner diameter of the printing slot, the outer diameter of the printing base plate is 0.1mm-0.5mm smaller than the outer diameter of the printing slot, and the printing base plate and the printing outer cylinder and the printing inner cylinder are sealed by wool felt or sealing rubber.

6. The binder jetting 3D printing device for cylindrical products according to claim 1, characterized in that: The long strip holes are arranged along the vertical direction, and there are at least two of the long strip holes.

7. The binder jetting 3D printing device for cylindrical products according to claim 1, characterized in that: The number of the bottom plate connecting rods, sleeve sliders and lifting mechanisms is consistent with the number of the long strip holes.

8. The binder jetting 3D printing device for cylindrical products according to claim 1, characterized in that: The lifting mechanism also includes a lifting motor, which is connected to a lifting screw through a coupling. The lifting mechanism is arranged on a bracket, and the lifting screw is connected to the bracket through a lead screw nut. The bracket is fixedly connected to the base plate.

9. The working method of the binder jetting 3D printing device for cylindrical products according to claim 4, characterized in that: When the printing device adopts the step-by-step printing method, the following steps are included: S200: The printing base plate drives the circular hoisting base plate to rise to the top; S201: The printing base plate drives the annular lifting base plate to descend by one layer thickness, and the sealing tape descends along with the printing base plate and is pressed against the inner cylinder of the printing to seal the long strip hole. The printing powder spreading mechanism rotates clockwise or counterclockwise with the powder replenishing position as the starting point. At this time, the nozzle does not work, the powder dropping trough is dropping powder, and the powder spreading scraper is spreading powder; S202: The printing powder spreading mechanism completes the spreading of a layer of powder by rotating one circle. When the printing powder spreading mechanism returns to the powder replenishing position again, it stops rotating and the powder dropping trough replenishes powder. S203: repeat steps S201 and S202 until the base powder is applied and the total thickness of the base powder is more than 20 times the thickness of the printing layer. After the base powder is applied, execute S204; S204: The printing base plate descends by one layer thickness, and the sealing tape descends along with the printing base plate and is pressed against the printing inner cylinder to seal the long strip hole. The printing powder spreading mechanism continues to rotate with the powder replenishing position as the starting point. At this time, the powder dropping trough drops powder, the powder spreading scraper spreads powder, and the nozzle sprays the adhesive. S205: The printing powder spreading mechanism rotates one circle to complete the spreading of a layer of powder and the sprayed binder forms a slice layer on the current layer of the model. When the printing powder spreading mechanism returns to the powder replenishing position again, it stops rotating, the nozzle stops spraying the binder, the powder drop trough replenishes powder, and the nozzle inkjet information is changed to the next slice layer of the model; S206: Repeat steps S204 and S205 until the powdering and adhesive spraying of all model slice layers are completed.

10. The working method of the binder jet 3D printing device suitable for cylindrical products according to claim 4, characterized in that: When the printing device adopts the continuous printing method, the following steps are included: S300: The printing base plate drives the circular hoisting base plate to rise to the top; S301: The printing powder spreading mechanism rotates clockwise or counterclockwise at a constant speed with the powder replenishing position as the starting point, and the printing base plate drives the annular hoisting base plate to descend at a constant speed. The time for the printing powder spreading mechanism to rotate one circle at a constant speed is equal to the time for the printing base plate to descend at a constant speed by one layer. That is, the printing base plate descends at a constant speed while spreading powder. At this time, the nozzle does not work, the powder dropping trough is dropping powder, the powder spreading scraper is spreading powder, and the sealing tape descends with the printing base plate and is close to the printing inner cylinder to form a seal for the long strip hole. S302: maintaining the rotation speed and the descending speed, and replenishing the powder in the powder drop chute during the time period of passing through the powder replenishing mechanism; S303: repeat steps S301 and S302 until the base powder is applied and the total thickness of the base powder is more than 20 times the thickness of the printing layer. After the base powder is applied, execute S304; S304: maintaining the rotation speed and the descending speed, the powder dropping trough drops powder, the powder spreading scraper spreads powder, and the nozzle sprays the binder; S305: When the printing powder spreading mechanism returns to the powder replenishing position again, a layer of powder is spread and the sprayed binder forms a slice layer on the current layer of the model, and the inkjet information of the nozzle is changed to the next slice layer of the model; S306: Repeat steps S304 and S305 until the powdering and adhesive spraying of all model slice layers are completed.

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