Special machine printing equipment and method for large circular ring type parts based on SLM

Abstract

The invention discloses special machine printing equipment and method for large circular ring type parts based on SLM, belongs to the technical field of 3D printing, and aims at the shape characteristics of the circular ring type parts, the special printing equipment is designed, and the structure and the function of the special printing equipment can adapt to the printing process of the parts to the maximum extent. Compared with general equipment, complex adjustment and adaptation are not needed, the printing task can be rapidly executed, the preparation time is shortened, and therefore the overall production efficiency is improved, the powder consumption is reduced, and the cost is saved. On the basis, the ventilation mode of the printing chamber is improved, an annular wind field is formed, and the situation that the quality of printed parts is abnormal is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of 3D printing, and specifically relates to a special machine printing device and method for large annular parts based on SLM. Background Art

[0002] Large ring parts are widely used in many fields, such as aircraft engine turbine outer rings, large bearing outer rings, slewing bearings (such as large ring parts in the rotating position of cranes and excavators), connecting flanges in other positions such as wind turbine towers, engine cylinder sleeves, etc. The existing SLM (selective laser melting) printing method for rings adopts rectangular and full-format printing. That is, a layer of powder is spread on a rectangular substrate, and after being scraped flat by a scraper, a layer is laser sintered, and parts are printed layer by layer. Among them, the unsintered part of the powder will be cleaned up at the end. It is equivalent to taking out a ring part from a rectangular parallelepiped. In this way, the waste of powder is serious and the efficiency is not high. For mass production of ring parts, the amount of powder waste is huge, especially high-value titanium metal powder, and the cost of mass printing such parts is high. Secondly, the existing ventilation method of rectangular and full-format printing is that the air enters one side of the printing room and the air is discharged on the other side, and the air flow flows in one direction. For ring parts that are blown by unidirectional airflow, one side cools down quickly and the other side cools down slowly, and the parts are easily deformed, affecting the printing quality. In addition, too fast wind speed will blow away lighter powders, and slow wind speed will affect the dust removal effect. For general large-format printing, the wind speed will gradually decay from one side to the other. It is difficult to achieve reasonable dust removal on the entire format without blowing away powders with smaller particle size and lighter mass. In the prior art, for example, a metal printing device and a printing control method for large annular parts disclosed in the patent with announcement number CN114289736A. The defects of this patent include that its scraper holder adopts a cantilever structure. The longer the cantilever, the worse the stability of the scraper rotation and the lower the powder flatness. The driving mechanism of the scraper is outside the molding chamber, and the scraper holder rotates in the molding chamber. During the metal powder printing process, it should be carried out in an inert gas environment, which makes it difficult to seal the rotating scraper holder. It does not have an excess powder discharge channel, which causes its excess powder to accumulate on the printing format, affecting the printing quality. Its air outlet is higher than the printing format, which means that the printing cylinder cannot be moved, and the powder and parts coexist in the cylinder after printing. When the cylinder cannot move, it will be very difficult to remove the parts. When the printing cylinder cannot move, the printing depth is also limited by the height of the molding chamber. In short, this patent is equivalent to giving a printing idea for ring-like parts, but it is difficult to apply in practice, and there is still a lack of effective 3D printing equipment dedicated to ring-like parts in the existing technology. Summary of the invention

[0003] In order to overcome the deficiencies in the background technology, the present invention provides a special machine printing device and method for large circular ring parts based on SLM, the purpose of which is to design a special printing device based on the shape characteristics of circular ring parts, and its structure and function can adapt to the printing process of such parts to the greatest extent. Compared with general equipment, there is no need for complex adjustments and adaptations, and it can quickly perform printing tasks and reduce preparation time, thereby improving overall production efficiency, reducing powder consumption, and saving costs. On this basis, the ventilation mode of the printing room is improved to form an annular wind field to reduce the abnormal quality of printed parts.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a special machine printing device for large circular ring parts based on SLM, comprising a printing chamber with a laser module on the top; a cylindrical cavity is provided inside the printing chamber; a movable cylindrical printing platform is docked at the bottom of the printing chamber; the printing platform comprises an outer cylinder body and an inner cylinder body both fixedly connected to the platform bottom plate, and an annular piston that can slide up and down is provided between the outer cylinder body and the inner cylinder body; the lower end of the annular piston is connected to a lifting drive mechanism for driving the annular piston to rise and fall; the top of the inner cylinder body is fixedly connected to an overflow powder funnel, and the overflow powder tube fixedly connected to the lower end of the overflow powder funnel is used to discharge the powder received by the overflow powder funnel out of the printing platform; the inner wall of the printing chamber is slidably connected to an annular dust cover for rotating the dust cover; a gear ring is fixedly connected to the outer side of the dust cover; a synchronous belt is sleeved on the gear ring, and its other One end is meshedly connected with a driving gear on an output shaft of a rotating motor fixedly connected to the side wall of the printing chamber, and is used for driving the dust cover to rotate through the rotating motor; an annular mounting plate is fixedly connected to the inner wall of the dust cover, and a scraper assembly is fixedly connected to the annular mounting plate; the scraper assembly includes a bracket fixedly connected to the annular mounting plate; a powder dropping pipe is fixedly connected to the bracket, and a powder dropping port at its lower end faces the annular piston, and a scraper located on the side of the powder dropping port is fixedly connected to the lower end of the bracket, and is used for driving the scraper to scrape the powder fallen on the annular piston when the dust cover rotates; the powder inlet at the upper end of the powder dropping pipe corresponds to the position of the powder supply interface fixedly arranged at the top of the printing chamber, and is used for when the powder dropping pipe rotates to the powder dropping position, the powder inlet faces the bottom of the powder supply interface; the powder supply interface is provided with an electrically controlled valve and is connected to the powder supply barrel located above the printing chamber through a powder supply pipe.

[0005] As a further optimization, it also includes a frame; the powder supply barrel is fixedly connected to the top of the frame; the printing chamber is fixedly connected to the middle of the frame; the platform bottom plate is fixedly connected to the top of the square box body, and the lifting drive mechanism is arranged in the square box body; the square box body is slidably connected to the lower part of the frame, and the end of the telescopic rod of the translation cylinder fixedly connected to the frame is fixedly connected to the square box body, which is used to push the square box body to translate through the translation cylinder so that the printing platform is docked at the bottom of the printing chamber.

[0006] As a further optimization, the lifting drive mechanism includes a lifting motor, a transmission box, a transfer case and a pair of left-right symmetrical lead screws; the middle part of the lead screw is inserted into the transfer case, the upper end thereof passes through the platform bottom plate and is connected to the annular piston, and the lower end thereof passes through the transfer case and extends out from under the square box body; the transmission box is arranged between the two transfer cases; a transmission shaft extends out from each side of the transmission box, and the end of the transmission shaft is transmission-connected to the transfer case; the output shaft of the lifting motor is connected to the transmission box, and is used to drive the two lead screws to rise and fall synchronously through the lifting motor.

[0007] As a further optimization, the lifting drive mechanism also includes a plurality of spline shafts, which are evenly distributed around the axial circumference of the annular piston; the top end of each spline shaft passes through the platform bottom plate and is fixedly connected to the annular piston, the middle part of the spline shaft is inserted into a spline sleeve preset at the bottom of the square box body, and the lower end thereof extends out of the square box body.

[0008] As a further optimization, a sieve plate is installed at the top of the overflow powder funnel; densely distributed sieve holes are provided around the sieve plate; the lower end of the ventilation disk abuts against the middle of the sieve plate, and its side wall is provided with evenly distributed ventilation holes, and its upper end is fixedly connected to a ventilation pipe, and the upper end of the ventilation pipe is fixedly connected to the printing room and passes through the outside of the printing room, and is used to ventilate the printing room by connecting an air blowing device; densely distributed air outlet holes are provided on the lower side wall of the printing room; the air outlet duct fixedly connected to the outer wall of the printing room corresponds to the position of the air outlet hole, and an air outlet interface is provided on the outer wall of the air outlet duct.

[0009] As a further optimization, the upper side wall of the printing chamber is provided with an air inlet hole for the sealing cloth; the air inlet duct fixedly connected to the outer wall of the printing chamber corresponds to the position of the air inlet hole; and the outer wall of the air inlet duct is provided with an air inlet interface.

[0010] As a further optimization, an inflatable annular sealing ring is fixedly provided at the edge of the upper port of the outer cylinder body; an annular groove corresponding to the annular sealing ring is provided at the edge of the bottom port of the printing chamber, so that the upper end of the annular sealing ring is embedded in the annular groove when the printing platform is docked at the bottom of the printing chamber.

[0011] As a further optimization, an upper powder falling sensor and a lower powder falling sensor are respectively provided at the upper and lower ends of the powder falling pipeline, which are respectively used to detect the upper and lower limit material levels of the powder in the powder falling pipeline.

[0012] As a further optimization, there are multiple powder dropping positions, which are evenly distributed around the axis circumference of the printing chamber; each powder dropping position is provided with a powder supply interface, and the upper end of each powder supply interface is connected to the powder supply barrel through a pipeline.

[0013] The present invention also provides a method for using a special machine printing device for large circular ring parts based on SLM, which comprises the following steps using the special machine printing device for large circular ring parts based on SLM as described above.

[0014] S1: The lifting drive mechanism controls the annular piston to move away from the top of the printing platform, and then moves the printing platform to the bottom of the printing chamber, so that the printing platform coincides with the axis in the printing chamber, and the annular piston 44 is directly below the scraper;

[0015] S2: The rotary motor drives the scraper assembly to rotate to the powder dropping position so that the powder dropping port is directly opposite to the bottom of the powder supply interface;

[0016] S3: the electrically controlled valve of the powder supply interface is opened, the powder enters the powder dropping pipeline, the powder dropping opening at the lower end of the powder dropping pipeline is restricted by the annular piston, and the powder accumulates in the powder dropping pipeline until the powder stored in the powder dropping pipeline reaches a predetermined amount, and the electrically controlled valve is closed;

[0017] S4: The rotary motor drives the scraper assembly to rotate, the powder drop port spreads powder evenly along the annular piston 44, the synchronously rotating scraper scrapes the powder flat on the annular piston, and the excess powder falls into the overflow powder funnel and is discharged outside the printing platform;

[0018] S5: The surface of the annular piston is evenly divided into at least two areas, A and B, and the powder dropping position is correspondingly located in area A; when the scraper assembly rotates one circle from the powder dropping position, area B starts printing;

[0019] S6: When the printing of area B is completed, the scraper assembly rotates to area B on the other side, and area A is printed;

[0020] S7: When the printing of area A and area B is completed, the lifting drive mechanism controls the annular piston to descend one layer;

[0021] S8: Repeat steps S2 to S7, printing layer by layer, until the part is printed;

[0022] S9: The lifting drive mechanism controls the annular piston to continue to descend for a distance until the top of the printed part is away from the top of the printing platform. After the printing platform is transferred to a pickup station away from the printing room, the lifting drive mechanism controls the annular piston to lift, push the printed part out of the top of the printing platform 4, and then take the part away to complete the printing of the part.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the annular piston of the present invention is the molding basis for annular parts, and the annular powder spreading and powder scraping greatly reduce the consumption of powder and save costs compared with the traditional rectangular powder spreading. Compared with the traditional rectangular powder spreading, the annular powder spreading and powder scraping of the present invention greatly improve the efficiency of powder spreading due to the reduction in the amount of powder spread, shorten the time for the laser module to suspend work, and improve the printing efficiency. The annular airflow formed in the printing chamber of the present invention can reduce smoke and dust while avoiding uneven hot and cold parts being printed, reduce deformation, and improve the quality of printing and molding. The partitioned printing method of the present invention can replenish powder for the scraper assembly while printing, reducing waiting time and further improving printing efficiency.

[0024] In summary, the present invention can adapt to the printing process of annular parts to the greatest extent; compared with general equipment, it does not require complicated adjustments and adaptations, can efficiently perform printing tasks, reduce powder consumption, save costs, and can improve the printing quality of annular parts; BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0026] Figure 2 is a schematic cross-sectional structural diagram of a printing chamber according to an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the internal three-dimensional structure of a printing chamber according to an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the three-dimensional structure of the dust cover according to an embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the three-dimensional structure of the scraper assembly according to an embodiment of the present invention;

[0030] Figure 6 It is a schematic diagram of the appearance of the assembly of the printing platform and the square box body according to an embodiment of the present invention;

[0031] Figure 7 for Figure 6 A schematic cross-sectional structure diagram of ;

[0032] Figure 8 A schematic diagram of the internal structure of a square box body according to an embodiment of the present invention;

[0033] Fig. 9 Schematic diagram of the AB area for partition printing according to an embodiment of the present invention.

[0034] The corresponding relationship between the technical features and the reference numerals in the figure is: powder supply barrel 1; frame 2; printing chamber 3; laser module 30; dust cover 31; annular mounting plate 311; annular guide rail mounting plate 312; annular guide rail 313; synchronous belt 32; scraper assembly 33; bracket 331; powder falling pipe 332; powder falling port 333; scraper 334; powder inlet 335; powder falling upper sensor 336; powder falling lower sensor 337; powder supply interface 34; spare powder supply interface 341; powder supply pipe 35; air outlet 36 ; air outlet duct 37; air inlet hole 38; air inlet duct 39; printing platform 4; platform bottom plate 41; outer cylinder body 42; inner cylinder body 43; annular piston 44; overflow powder funnel 45; sieve plate 451; sieve hole 452; overflow powder pipe 46; annular sealing ring 47; annular groove 48; square box body 5; lifting motor 51; transmission box 52; transfer box 53; screw 54; transmission shaft 55; spline shaft 56; spline sleeve 57; translation cylinder 6; pick-up station 61; ventilation plate 7; vent 71; ventilation pipe 73. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the preferred embodiments of the present invention, rather than all the embodiments. It should be understood by those skilled in the art that these implementation modes are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0036] Example; see Figure 1-9 .

[0037] The present invention provides the following technical solution: a special machine printing device for large ring-like parts based on SLM, and the components and functions of the device are as follows.

[0038] Powder supply barrel 1 is responsible for the powder supply of the equipment.

[0039] The frame 2 is responsible for supporting the powder supply barrel 1 .

[0040] Printing chamber 3 is responsible for the printing and forming of parts. It adopts a cylindrical design to match circular ring parts. At the same time, a sealed design is adopted to ensure that the printing process is carried out in a stable environment to prevent interference from external factors. High-precision sensors are installed in the chamber to monitor parameters such as temperature, humidity, and oxygen content in real time for precise printing control. The internal space of the chamber has been optimized to accommodate circular ring parts of different sizes for printing, while ensuring that the powder spreading port has sufficient moving space, and the cylindrical design is more suitable for annular wind fields. During the laser printing process, impurities in the format will appear in the smoke and dust, which will affect the penetration of the laser. In order to avoid the accumulation of smoke and dust, the annular wind field is more conducive to the diffusion and discharge of smoke and dust, thereby improving the efficiency of the laser. At the same time, it also avoids uneven cooling of parts, reduces deformation of parts, and improves the molding quality of parts.

[0041] The printing platform 4 is responsible for printing and forming parts and taking out the parts after printing. After printing is completed, the printing platform 4 moves to a barrier-free place on one side for easy removal. It includes a lifting annular piston 44 that matches the shape of the annular parts. The platform is made of high-strength material and can withstand the high temperature and pressure during metal printing, while ensuring the stability and accuracy of lifting.

[0042] The frame 2 is responsible for the installation foundation of various components and provides support for the printing chamber, printing platform 4 and other devices.

[0043] The cylinder is responsible for the movement of the printing platform 4.

[0044] Among them, the components and functions of the printing chamber 3 are as follows.

[0045] The powder dropping interface realizes the powder supply to the scraper assembly 33 and controls the powder supply amount through the electric control valve.

[0046] The optical module is responsible for generating laser to print parts.

[0047] The upper powder falling sensor 336 and the lower powder falling sensor 337 are responsible for detecting the position of the powder in the scraper assembly 33 .

[0048] The scraper assembly 33 is responsible for spreading and storing powder.

[0049] The dust cover 31 and the scraper assembly 33 are installed on the dust cover 31 , and the dust cover 31 is responsible for the circular motion of the scraper assembly 33 .

[0050] The ventilation plate 7 is responsible for directing the airflow to the bottom of the printing chamber 3 and evenly diffusing it.

[0051] The air outlet holes 36 and the air outlet duct 37 are responsible for discharging the airflow rich in smoke and dust; together with the ventilation disk 7, they create an annular wind field.

[0052] The air inlet hole 38 and the air inlet duct 39 are responsible for strengthening the flow of air and accelerating the exhaust of smoke and dust.

[0053] The spare powder dropping interface is responsible for adding powder to the scraper assembly 33 in the non-printing area to improve the efficiency of adding powder.

[0054] The components and functions of the dust cover 31 are as follows.

[0055] The annular guide rail mounting plate 312 is fixedly connected to the printing chamber 3 and is responsible for supporting the annular guide rail.

[0056] The annular guide rail 313 is responsible for maintaining high-precision rotation of the dust cover 31 .

[0057] The synchronous belt 32 meshes with the gear ring on the outer wall of the dust cover 31 to transmit power and drive the dust cover 31 to rotate with high precision.

[0058] The synchronous wheel is connected to the output shaft of the rotating motor and is provided with a synchronous belt to provide power for the dust cover 31 to rotate.

[0059] The annular mounting plate 311 is fixedly connected to the inner side of the dust cover 31 and is connected to the scraper assembly 33 , serving as a supporting base for the scraper assembly 33 .

[0060] The components and functions of the scraper assembly 33 are as follows.

[0061] The powder dropping pipeline 332 is responsible for receiving powder from the powder dropping interface, transporting it to the powder dropping port 333, and storing powder.

[0062] The powder dropping fixing plate is responsible for fixing the powder dropping pipe 332 .

[0063] The fixing plate is assembled to connect the scraper assembly 33 with the dust cover 31 .

[0064] Reinforcement ribs: Because the powder dropping pipe 332 is a thin-walled part, reinforcement ribs are provided here to withstand the radial force during the powder spreading process and prevent the powder dropping pipe 332 from being deformed due to excessive force.

[0065] The scraper mounting block is used to mount the scraper 334 so that the scraper 334 and the scraper assembly 33 become a whole.

[0066] The scraper 334 is made of rubber and is used for spreading powder. The scraper 334 is installed in an eight-shaped shape, and can discharge excess powder to the overflow powder funnel 45 during the powder spreading process. Two scrapers 334 are arranged on both sides of the powder outlet 333, so that the powder can be scraped flat from both directions.

[0067] The powder drop opening 333 is used to spread powder onto the surface of the annular piston 44 .

[0068] Among them, the components and functions of the printing platform 4 are as follows.

[0069] The outer cylinder body 42 and the inner cylinder body 43 are both fixedly connected to the platform bottom plate 41 to form an annular space, which is the molding space.

[0070] The sealing ring is inflatable and is responsible for sealing the printing platform 4 and the printing chamber.

[0071] The overflow powder funnel 45 is responsible for transferring away the excess powder.

[0072] The annular piston 44 is driven by the lifting drive mechanism to move up and down.

[0073] The various parts and functions of the overflow powder funnel 45 are as follows.

[0074] The funnel is responsible for collecting excess powder.

[0075] The powder overflow pipe 46 is connected to the bottom of the funnel, and its end obliquely passes through the platform bottom plate 41, does not interfere with the lifting drive mechanism, and is responsible for discharging the powder in the funnel to the printing platform 4. Its end is connected to the receiving device to avoid disorderly discharge of powder.

[0076] The sieve plate 451 is buckled and covered on the top of the funnel. The middle part of the sieve plate is a closed circle. The sieve holes 452 are arranged around the sieve plate. The sieve holes 452 are close to the piston plate. The excess powder on the piston plate falls into the funnel through the sieve holes 452.

[0077] Among them, the components and functions of the lifting drive mechanism are as follows.

[0078] The lifting motor 51 is fixedly connected in the square box body 5 and is responsible for providing the lifting power.

[0079] The square box body 5 is responsible for providing a foundation for installing various components and is connected to the printing platform 4 by connecting to the platform bottom plate 41 .

[0080] The spline shaft 56 has an upper end connected to the annular piston 44 and a lower end passing through a spline sleeve 57 fixed at the bottom of the square box body 5, which is responsible for motion guidance to ensure that the annular piston 44 is lifted and lowered smoothly in a horizontal posture.

[0081] The upper end of the lead screw 54 is connected to the annular piston 44 and is responsible for pushing and pulling the annular piston 44 .

[0082] The transfer case 53 has a lead screw 54 and a nut therein, which are responsible for driving the lead screw 54 to move up and down.

[0083] One end of the transmission shaft 55 is inserted into the transfer case 53 and connected to a pinion gear, which meshes with a bevel gear fixed to one end of the screw 54 nut and is responsible for transmitting power to the screw 54 nut.

[0084] The transmission box 52 is connected to the other end of the transmission shaft 55 , and a gear transmission mechanism is arranged inside the transmission box 52 , which is responsible for equally dividing the power of the output shaft of the lifting motor 51 to the two transmission shafts 55 .

[0085] It can be seen that the special machine printing device at least includes a printing chamber 3 with a laser module 30 on the top; a cylindrical cavity is provided inside the printing chamber 3; a movable cylindrical printing platform 4 is docked at the bottom of the printing chamber 3; the printing platform 4 includes an outer cylinder body 42 and an inner cylinder body 43 both fixedly connected to the platform bottom plate 41, and an annular piston 44 that can slide up and down is provided between the outer cylinder body 42 and the inner cylinder body 43; the lower end of the annular piston 44 is connected to the lifting drive mechanism for driving the The annular piston 44 is raised and lowered; the top of the inner cylinder body 43 is fixedly connected to the overflow powder funnel 45, and the overflow powder pipe 46 fixedly connected to the lower end of the overflow powder funnel 45 is used to discharge the powder received by the overflow powder funnel 45 out of the printing platform 4; the inner wall of the printing chamber 3 is slidably connected to the annular dust cover 31, so that the dust cover 31 can rotate; a gear ring is fixedly connected to the outer side of the dust cover 31; a synchronous belt 32 is sleeved on the gear ring, and the other end of the synchronous belt 32 is connected to the output shaft of the rotating motor fixedly connected to the side wall of the printing chamber 3. The driving gear is meshed and connected to drive the dust cover 31 to rotate through the rotating motor; an annular mounting plate is fixedly connected to the inner wall of the dust cover 31, and a scraper assembly 33 is fixedly connected to the annular mounting plate 311; the scraper assembly 33 includes a bracket 331 fixedly connected to the annular mounting plate 311; a powder dropping pipe 332 is fixedly connected to the bracket 331, and a powder dropping port 333 at the lower end thereof faces the annular piston 44, and a scraper 334 located on the side of the powder dropping port 333 is fixedly connected to the bracket 3 The lower end of 31 is used to drive the scraper 334 to scrape the powder falling on the annular piston 44 when the dust cover 31 rotates; the powder inlet 335 at the upper end of the powder dropping pipe 332 corresponds to the position of the powder supply interface 34 fixed on the top of the printing chamber 3, and is used for when the powder dropping pipe 332 rotates to the powder dropping position, the powder inlet 335 is directly opposite to the bottom of the powder supply interface 34; the powder supply interface 34 is provided with an electric control valve and is connected to the powder supply barrel 1 located above the printing chamber 3 through the powder supply pipe 35.

[0086] When in use, the steps for using the dedicated printing device of this embodiment are as follows.

[0087] S1: The lifting drive mechanism controls the annular piston 44 to move away from the top of the printing platform 4, and then moves the printing platform 4 to dock with the bottom of the printing chamber 3, so that the printing platform 4 coincides with the axis in the printing chamber 3. At this time, the annular piston 44 is directly opposite to the scraper 334.

[0088] S2: The rotary motor drives the scraper assembly 33 to rotate to the powder dropping position, so that the powder dropping port 333 is directly opposite to the bottom of the powder supply interface 34.

[0089] S3: The electrically controlled valve of the powder supply interface 34 is opened, and the powder enters the powder dropping pipe 332. The powder dropping port 333 at the lower end of the powder dropping pipe 332 is restricted by the annular piston 44, and the powder accumulates in the powder dropping pipe 332 until the powder stored in the powder dropping pipe 332 reaches a predetermined amount, and the electrically controlled valve is closed.

[0090] S4: The rotating motor drives the scraper assembly 33 to rotate, and the powder outlet 333 spreads powder evenly along the annular piston 44. The synchronously rotating scraper 334 scrapes the powder on the annular piston 44, and the excess powder falls into the overflow powder funnel 45 and is discharged outside the printing platform 4.

[0091] S5: The surface of the annular piston 44 is evenly divided into at least two areas A and B, and the powder dropping position is correspondingly located in area A; when the scraper assembly 33 rotates one circle from the powder dropping position, area B starts printing.

[0092] S6: After the printing of area B is completed, the scraper assembly 33 rotates to area B on the other side, and area A is printed.

[0093] S7: After the printing of both area A and area B is completed, the lifting drive mechanism controls the annular piston 44 to descend one layer.

[0094] S8: Repeat steps S2 to S7, printing layer by layer, until the part is printed.

[0095] S9: The lifting drive mechanism controls the annular piston 44 to continue to descend for a distance until the top of the printed part is away from the top of the printing platform 4, and then the printing platform 4 is transferred to the retrieval station 61 away from the printing chamber 3. The lifting drive mechanism controls the annular piston 44 to lift, push the printed part out of the top of the printing platform 4, and then take the part away to complete the printing of the part.

[0096] Among them, in step S3, the predetermined amount of powder stored in the powder falling pipeline 332 can be controlled by timing, that is, the predetermined amount can be controlled by opening the electric control valve for a period of time. However, the timing control is not accurate enough. In order to more accurately control the storage amount of the powder falling pipeline 332, a detection amount control is added, and an upper powder falling sensor 336 and a lower powder falling sensor 337 are respectively provided at the upper and lower ends of the powder falling pipeline 332, which are used to detect the upper and lower limit material levels of the powder in the powder falling pipeline 332. When the powder in the powder falling pipeline 332 is lower than the detection value of the lower powder falling sensor 337, the electric control valve opens until the powder in the powder falling pipeline 332 is higher than the detection value of the upper powder falling sensor 336, and then the electric control valve closes. At this time, the predetermined amount is controlled by the detection amount of the upper powder falling sensor 336 and the lower powder falling sensor 337, which is more accurate.

[0097] In step S4, according to the different powder consumption of the parts, if the predetermined amount of powder stored in the powder dropping pipeline 332 is insufficient, a spare powder dropping position with a spare powder supply interface 341 can be set in area B. When printing area A in step S6, the scraper assembly 33 in area B adds powder at the same time to improve the powder adding efficiency. Similarly, multiple printing partitions can be set to meet the needs of printing parts with different powder consumption.

[0098] Among them, in step S9, it is preferred that a detachable annular substrate is installed on the upper end of the annular piston 44. When the parts are removed, the annular substrate is removed together to avoid cutting and repairing processes between the bottom of the parts and the annular piston 44, which is efficient and ensures the service life of the annular piston 44.

[0099] In order to provide an installation foundation for the printing chamber 3 and the printing platform 4, in another embodiment, it also includes a frame 2; the powder supply barrel 1 is fixedly connected to the top of the frame 2; the printing chamber 3 is fixedly connected to the middle of the frame 2; the platform bottom plate 41 is fixedly connected to the top of the square box body 5, and the lifting drive mechanism is arranged in the square box body 5; the square box body 5 is slidably connected to the lower part of the frame 2, and the end of the telescopic rod of the translation cylinder 6 fixedly connected to the frame 2 is fixedly connected to the square box body 5, which is used to push the square box body 5 to translate through the translation cylinder 6 so that the printing platform 4 is docked at the bottom of the printing chamber 3.

[0100] In another embodiment, the printing platform 4 is arranged in the frame 2 so that it can be lifted and lowered by a cylinder, so that after printing is completed, the printing platform 4 can be lowered away from the printing chamber 3, and then the printed parts can be taken out, although the printing task can still be completed. However, this method occupies more height space, and the powder supply barrel 1, the printing chamber 3 and other components are relatively high, which is inconvenient for maintenance, and its effect is not as good as the previous printing platform 4 that moves horizontally.

[0101] In another embodiment, the annular piston 44 can be connected to a lifting mechanism such as an air cylinder or an oil cylinder, although the printing task can still be completed. However, this method is not precise enough to control the annular piston 44. The preferred embodiment of this embodiment is that the lifting drive mechanism includes a lifting motor 51, a transmission box 52, a transfer box 53 and a pair of left-right symmetrical lead screws 54; the middle part of the lead screw 54 is inserted into the transfer box 53, its upper end passes through the platform bottom plate 41 and is connected to the annular piston 44, and its lower end passes through the transfer box 53 and extends below the square box body 5; the transmission box 52 is arranged between the two transfer boxes 53; a transmission shaft 55 extends from each side of the transmission box 52, and the end of the transmission shaft 55 is connected to the transfer box 53 in a transmission manner; the output shaft of the lifting motor 51 is connected to the transmission box 52, and is used to drive the two lead screws 54 to rise and fall synchronously through the lifting motor 51. The lifting motor 51 drives the annular piston 44 to move up and down through the transmission box 52, the transfer box 53 and the lead screw 54, so that the control is more precise and it is convenient for printing layer by layer.

[0102] In another embodiment, a cylindrical guide shaft or a square shaft can play a guiding role. The preferred embodiment of this embodiment is that the lifting drive mechanism also includes a plurality of spline shafts 56, which are evenly distributed around the axis of the annular piston 44; the top of each spline shaft 56 passes through the platform bottom plate 41 and is fixedly connected to the annular piston 44, and the middle part is inserted into the spline sleeve 57 preset at the bottom of the square box body 5, and the lower end thereof extends out of the square box body 5. The contact area between the spline shaft 56 and the spline sleeve 57 is larger, which can better play a guiding role, and the lifting and lowering of the annular piston 44 is more stable.

[0103] In order to ventilate the printing chamber 3 and avoid smoke accumulation that affects the function of the laser, a sieve plate 451 is installed at the top of the overflow powder funnel 45; dense sieve holes 452 are arranged around the sieve plate 451; the lower end of the ventilation plate 7 is against the middle of the sieve plate 451, and its side wall is provided with uniform ventilation holes 71, and its upper end is fixedly connected to a ventilation pipe 73, and the upper end of the ventilation pipe 73 is fixedly connected to the printing chamber 3 and passes through the outside of the printing chamber 3, which is used to ventilate the inside of the printing chamber 3 by connecting a blasting device; dense air outlet holes 36 are arranged on the lower side wall of the printing chamber 3; the air outlet duct 37 fixedly connected to the outer wall of the printing chamber 3 corresponds to the position of the air outlet hole 36, and the outer wall of the air outlet duct 37 is provided with an air outlet interface. The sieve plate 451 does not hinder the discharge of excess powder. The ventilation plate 7 and the air outlet holes 36 cooperate to form a circumferentially uniform ventilation system in the printing chamber 3, which reduces smoke and dust, avoids uneven hot and cold of the printed parts, and reduces deformation.

[0104] In order to enhance ventilation, the upper side wall of the printing chamber 3 is provided with an air inlet hole 38 of a sealing cloth; an air inlet duct 39 fixedly connected to the outer wall of the printing chamber 3 corresponds to the position of the air inlet hole 38; an air inlet interface is provided on the outer wall of the air inlet duct 39. On the basis of the annular wind field, an airflow from top to bottom is formed to prevent smoke and dust from contaminating the lens of the laser module 30, which can better discharge smoke and dust and extend the service life.

[0105] For better sealing, an inflatable annular sealing ring 47 is fixedly provided at the upper edge of the outer cylinder 42; an annular groove 48 corresponding to the annular sealing ring 47 is provided at the bottom edge of the printing chamber 3, so that when the printing platform 4 is docked at the bottom of the printing chamber 3, the upper end of the annular sealing ring 47 is embedded in the annular groove 48. When in use, after the printing platform 4 is docked with the printing chamber 3, the annular sealing ring 47 is inflated and embedded in the annular groove 48, so as to seal the joint between the printing platform 4 and the printing chamber 3 and ensure the sealing of the printing chamber 3.

[0106] In order to better control the amount of powder in the powder falling pipe 332, an upper powder falling sensor 336 and a lower powder falling sensor 337 are respectively provided at the upper and lower ends of the powder falling pipe 332, which are respectively used to detect the upper and lower limit material levels of the powder in the powder falling pipe 332.

[0107] In order to improve the powder adding efficiency, there are multiple powder dropping positions, which are evenly distributed around the axis of the printing chamber 3; each powder dropping position is provided with a powder supply interface 34, and the upper end of each powder supply interface 34 is connected to the powder supply barrel 1 through a pipeline.

[0108] The advantage of this embodiment is that the annular piston 44 of the present invention is the molding basis for annular parts, and the annular powder spreading and scraping greatly reduce the consumption of powder and save costs compared with the traditional rectangular powder spreading. Compared with the traditional rectangular powder spreading, the annular powder spreading and scraping of the present invention greatly improves the efficiency of powder spreading due to the reduction in the amount of powder spread, shortens the time for the laser module 30 to suspend work, and improves the printing efficiency. The annular airflow formed in the printing chamber 3 of the present invention can reduce smoke and dust, avoid uneven hot and cold parts being printed, reduce deformation, and improve the quality of printing. The partitioned printing method of the present invention can replenish powder for the scraper assembly 33 while printing, reducing waiting time and further improving printing efficiency.

[0109] In summary, the present invention can adapt to the printing process of ring-like parts to the greatest extent; compared with general equipment, it does not require complicated adjustments and adaptations, can efficiently perform printing tasks, reduce powder consumption, save costs, and can improve the printing quality of ring-like parts.

[0110] The parts not described in detail in the present invention are prior art; for ordinary technicians in the field, the technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A special machine printing device for large ring-like parts based on SLM, comprising a printing chamber (3) with a laser module (30) on the top; characterized in that: The printing chamber (3) has a cylindrical cavity inside; a movable cylindrical printing platform (4) is docked at the bottom of the printing chamber (3); the printing platform (4) comprises an outer cylinder (42) and an inner cylinder (43) both of which are fixedly connected to the platform bottom plate (41); an annular piston (44) that can slide up and down is provided between the outer cylinder (42) and the inner cylinder (43); the lower end of the annular piston (44) is connected to a lifting drive mechanism for driving the annular piston (44) to move up and down; the top of the inner cylinder (43) is fixedly connected to an overflow powder funnel (45); the lower end of the overflow powder funnel (45) is fixedly connected to an overflow powder pipe (46) for discharging powder received by the overflow powder funnel (45) out of the printing platform (4); The inner wall of the printing chamber (3) is slidably connected to the annular dust cover (31) so that the dust cover (31) can rotate; a gear ring is fixedly connected to the outer side of the dust cover (31); a synchronous belt (32) is sleeved on the gear ring, and the other end of the synchronous belt (32) is meshedly connected to a driving gear on an output shaft of a rotating motor fixedly connected to the side wall of the printing chamber (3), so as to drive the dust cover (31) to rotate through the rotating motor; an annular mounting plate (311) is fixedly connected to the inner wall of the dust cover (31), and a scraper assembly (33) is fixedly connected to the annular mounting plate (311); The scraper assembly (33) comprises a bracket (331) fixedly connected to the annular mounting plate (311); a powder dropping pipe (332) is fixedly connected to the bracket (331), a powder dropping port (333) at the lower end of the powder dropping pipe (332) is directly opposite to the annular piston (44), and a scraper (334) located on the side of the powder dropping port (333) is fixedly connected to the lower end of the bracket (331) for driving the scraper (334) to scrape the powder dropped on the annular piston (44) when the dust cover (31) rotates. The powder on the shaped piston (44) is collected; the powder inlet (335) at the upper end of the powder dropping pipeline (332) corresponds to the position of the powder supply interface (34) fixedly arranged at the top of the printing chamber (3), so that when the powder dropping pipeline (332) rotates to the powder dropping position, the powder inlet (335) is directly opposite to the bottom of the powder supply interface (34); the powder supply interface (34) is provided with an electric control valve and is connected to the powder supply barrel (1) located above the printing chamber (3) through the powder supply pipeline (35).

2. According to claim 1, a special machine printing device for large ring-like parts based on SLM is characterized in that: The printing platform (4) is connected to the bottom of the printing chamber (3) by pushing the square box body (5) to move in translation.

3. The SLM-based special machine printing device for large ring-like parts according to claim 2 is characterized in that: The lifting drive mechanism comprises a lifting motor (51), a transmission box (52), a transfer box (53) and a pair of bilaterally symmetrical lead screws (54); the middle portion of the lead screw (54) is inserted into the transfer box (53), the upper end of the lead screw (54) passes through the platform bottom plate (41) and is connected to the annular piston (44), and the lower end of the lead screw (54) passes through the transfer box (53) and extends out from below the square box body (5); the transmission box (52) is arranged between the two transfer boxes (53); a transmission shaft (55) extends from each side of the transmission box (52), and the end of the transmission shaft (55) is transmission-connected to the transfer box (53); the output shaft of the lifting motor (51) is connected to the transmission box (52) and is used to drive the two lead screws (54) to rise and fall synchronously through the lifting motor (51).

4. The SLM-based special machine printing device for large ring-like parts according to claim 3 is characterized by: The lifting drive mechanism further comprises a plurality of spline shafts (56) uniformly distributed around the axis of the annular piston (44); the top end of each spline shaft (56) passes through the platform bottom plate (41) and is fixedly connected to the annular piston (44), the middle portion of the spline shaft (56) is inserted into a spline sleeve (57) preset at the bottom of the square box body (5), and the lower end thereof protrudes out of the square box body (5).

5. According to claim 1, a special machine printing device for large ring-like parts based on SLM is characterized in that: A sieve plate (451) is installed at the top of the overflow powder funnel (45); densely distributed sieve holes (452) are provided around the sieve plate (451); the lower end of the ventilation plate (7) abuts against the middle of the sieve plate (451); the side wall of the ventilation plate (7) is provided with evenly distributed ventilation holes (71); the upper end of the ventilation plate (7) is fixedly connected to a ventilation pipe (73); the upper end of the ventilation pipe (73) is fixedly connected to the printing chamber (3) and passes through the outside of the printing chamber (3) for ventilating the inside of the printing chamber (3) by connecting to an air blowing device; densely distributed air outlet holes (36) are provided on the lower side wall of the printing chamber (3); an air outlet duct (37) fixedly connected to the outer wall of the printing chamber (3) corresponds to the position of the air outlet holes (36), and an air outlet interface is provided on the outer wall of the air outlet duct (37).

6. The SLM-based special machine printing device for large ring-like parts according to claim 5, characterized in that: The upper side wall of the printing chamber (3) is provided with an air inlet hole (38) for sealing the cloth; an air inlet duct (39) fixedly connected to the outer wall of the printing chamber (3) is located at a position corresponding to the air inlet hole (38); and an air inlet interface is provided on the outer wall of the air inlet duct (39).

7. The SLM-based special machine printing device for large ring-like parts according to claim 1, characterized in that: An inflatable annular sealing ring (47) is fixedly provided at the upper edge of the outer cylinder body (42); an annular groove (48) corresponding to the annular sealing ring (47) is provided at the bottom edge of the printing chamber (3), so that when the printing platform (4) is docked at the bottom of the printing chamber (3), the upper end of the annular sealing ring (47) is embedded in the annular groove (48).

8. The SLM-based special machine printing device for large ring-like parts according to claim 1, characterized in that: An upper powder falling sensor (336) and a lower powder falling sensor (337) are respectively provided at the upper and lower ends of the powder falling pipeline (332), and are respectively used to detect the upper and lower limit material levels of the powder in the powder falling pipeline (332).

9. The SLM-based special machine printing device for large ring-like parts according to claim 1, characterized in that: There are a plurality of powder dropping positions, which are evenly distributed around the axis of the printing chamber (3); each of the powder dropping positions is provided with a powder supply interface (34), and the upper end of each of the powder supply interfaces (34) is connected to the powder supply barrel (1) via a pipeline.

10. A method for using a special machine printing device for large ring-like parts based on SLM, characterized in that: The special machine printing device for large ring-like parts based on SLM as claimed in any one of claims 1 to 9 comprises the following steps: S1: the lifting drive mechanism controls the annular piston (44) to move away from the top of the printing platform (4), and then moves the printing platform (4) to dock with the bottom of the printing chamber (3), so that the axis of the printing platform (4) and the printing chamber (3) coincide with each other, and at this time, the annular piston (44) is directly below the scraper (334); S2: the rotary motor drives the scraper assembly (33) to rotate to a powder dropping position, so that the powder dropping opening (333) is directly opposite to the bottom of the powder supply interface (34); S3: the electrically controlled valve of the powder supply interface (34) is opened, and the powder enters the powder dropping pipeline (332). The powder dropping opening (333) at the lower end of the powder dropping pipeline (332) is restricted by the annular piston (44), and the powder accumulates in the powder dropping pipeline (332) until the powder stored in the powder dropping pipeline (332) reaches a predetermined amount, and the electrically controlled valve is closed; S4: the rotary motor drives the scraper assembly (33) to rotate, the powder drop port (333) evenly spreads powder along the annular piston (44), the synchronously rotating scraper (334) scrapes the powder on the annular piston (44) flat, and the excess powder falls into the overflow powder funnel (45) and is discharged outside the printing platform (4); S5: the surface of the annular piston (44) is evenly divided into at least two areas A and B, the powder dropping position being located in area A; when the scraper assembly (33) rotates one circle from the powder dropping position, area B starts printing; S6: When the printing of area B is completed, the scraper assembly (33) rotates to area B on the other side, and area A is printed; S7: When the printing of area A and area B is completed, the lifting drive mechanism controls the annular piston (44) to descend one layer; S8: Repeat steps S2 to S7, printing layer by layer, until the part is printed; S9: The lifting drive mechanism controls the annular piston (44) to continue to descend for a certain distance until the top of the printed part is away from the top of the printing platform (4), and then the printing platform (4) is transferred to a pickup station away from the printing chamber (3). The lifting drive mechanism controls the annular piston (44) to lift up, pushes the printed part out of the top of the printing platform (4), and then removes the part to complete the printing of the part.

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