Adsorption-type multi-material additive powder spreading system and powder spreading method based on micropore array

Abstract

The present invention discloses an adsorption-type multi-material additive powder spreading system and a powder spreading method based on a micropore array. The powder spreading system comprises a forming chamber, a powder supply device, a powder spreading device and a powder scraping device; a forming platform is arranged in the forming chamber; the powder spreading device comprises a mesh screen, a vacuum pump and a powder dropping mechanism. The mesh screen and the vacuum pump cooperate to evenly adsorb powder particles on the periphery of the mesh screen, and the powder particles will not pass through the micropores to enter the interior of the mesh screen, nor will they completely cover the micropores, so that the airflow can still pass through the gaps between the micropores and the powder particles, and can continue to adsorb more powder particles, and then some of the powder particles are scraped off by the powder scraping device, so as to accurately control the thickness of the powder adsorbed on the periphery of the mesh screen. When spreading the powder, the powder dropping mechanism will spread the powder particles on the periphery of the mesh screen onto the forming platform, so that a variety of powder materials can be evenly and accurately spread in the corresponding areas, so as to solve the problem of accurately spreading different powders in one layer, and realize XY plane multi-material additive manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to an adsorption-type multi-material additive powder spreading system and a powder spreading method based on a micropore array. Background Art

[0002] Additive manufacturing is a new bottom-up material forming method that manufactures three-dimensional entities by stacking materials. As a cutting-edge branch of additive manufacturing technology, multi-material additive manufacturing can achieve rapid design and direct manufacturing of three-dimensional objects composed of multiple materials without complex manufacturing processes and expensive molds, thus greatly expanding the application scope and possibilities of additive manufacturing. Parts produced using multi-material additive manufacturing can achieve comprehensive optimization of performance, integrating the best properties of different materials to create parts with excellent comprehensive performance.

[0003] At present, by replacing different powder laying components, it is possible to achieve multi-material additive manufacturing of parts along the Z-axis direction. However, it is still a huge challenge to achieve multi-material additive manufacturing with variable materials in the XY plane. How to lay powder evenly and accurately in the corresponding area and prevent powders from contaminating each other are still urgent issues that need to be solved. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide an adsorption-type multi-material additive powder laying system based on a micropore array, which can evenly and accurately lay a variety of powder materials in the corresponding area, solve the problem of accurately laying different powders in a layer, and realize XY plane multi-material additive manufacturing.

[0005] In order to solve the above problems, the technical solution adopted by the present invention is as follows: an adsorption-type multi-material additive powder spreading system based on a micropore array, comprising a forming chamber, a powder supply device and a powder spreading device; a forming platform and a moving platform are arranged in the forming chamber, and the moving platform can move above the forming platform for powder spreading; the powder supply device is arranged on the forming chamber and distributed in plurality, and is used to provide powders of various materials; the powder spreading device is arranged on the moving platform and distributed in plurality, and when supplying powder, the plurality of the powder spreading devices are respectively located below the plurality of the powder supply devices, and each of the powder spreading devices comprises a mesh screen, a vacuum pump and a powder dropping device. The mesh screen is rotatably connected to the mobile platform, the periphery of the mesh screen has a plurality of polygonal micropores distributed in a circular array, the inscribed circle diameter D1 of the micropores is less than the outer diameter d of the powder particles and less than the circumscribed circle diameter D2 of the micropores, the vacuum pump can draw suction from the inside of the mesh screen to adsorb the powder particles dropped from the powder supply device on the periphery of the mesh screen, the powder scraping device is located on the side of the mesh screen, and is used to scrape off part of the powder particles on the periphery of the mesh screen so that the powder thickness on the periphery of the mesh screen reaches the desired thickness, and the powder dropping mechanism is used to spread the powder particles on the periphery of the mesh screen onto the forming platform.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] 1. The powder spreading system is equipped with multiple powder supply devices and multiple powder spreading devices. Multiple powder supply devices can provide powders of multiple materials, and multiple powder spreading devices can spread powders of multiple materials, which can prevent mutual contamination between powders, meet the additive manufacturing needs of complex multi-material parts, and can be used to manufacture complex components with different material performance combinations;

[0008] 2. The powder spreading system adopts a mesh screen and a vacuum pump to cooperate, which can evenly adsorb the powder particles on the periphery of the mesh screen, and the inscribed circle diameter D1 of the micropores is less than the outer diameter d of the powder particles and less than the circumscribed circle diameter D2 of the micropores. Therefore, when the vacuum pump sucks inside the mesh screen, the powder particles will only be adsorbed on the periphery of the mesh screen and will not pass through the micropores to enter the inside of the mesh screen, and the powder particles will not completely cover the micropores, so that the airflow can still pass through the gap between the micropores and the powder particles, thereby maintaining the pressure difference between the inside and outside of the mesh screen, and can continue to adsorb more powder particles, and then use the powder scraping device to scrape off some of the powder particles to accurately control the thickness of the powder adsorbed on the periphery of the mesh screen. Finally, the mobile platform drives the powder spreading device to move above the forming platform, and the powder dropping mechanism spreads the powder particles on the periphery of the mesh screen onto the forming platform, so that a variety of powder materials can be evenly and accurately spread in the corresponding area, solving the problem of accurately laying different powders in one layer, and realizing XY plane multi-material additive manufacturing.

[0009] The above-mentioned adsorption-type multi-material additive powder spreading system based on micropore array also includes a laser device, a control device and a gas circulation device; the laser device is arranged above the forming platform, and is used to emit laser toward the forming platform to melt the powder on the forming platform; the control device is electrically connected to the mobile platform, the powder supply device, the powder spreading device and the powder scraping device, and is used to control the working states of the mobile platform, the powder supply device, the powder spreading device and the powder scraping device; the gas circulation device is used to provide an inert gas environment in the forming chamber during the working process.

[0010] The above-mentioned adsorption-type multi-material additive powder spreading system based on micropore array, the powder spreading device also includes a bracket, the bracket is arranged inside the mesh screen, the powder dropping mechanism includes a ejector pin, and the ejector pin is telescopically connected to the bracket; the lower end of the ejector pin has a curved surface, when powder spreading is required, the ejector pin can move toward the micropores inside the mesh screen so that the curved surface blocks the micropores, thereby reducing or eliminating the adsorption force on the powder particles, and falling onto the forming platform under the action of gravity, when powder spreading is not required, the ejector pin can move away from the micropores to open the micropores, thereby allowing the powder particles to be adsorbed to the periphery of the mesh screen.

[0011] In the above-mentioned adsorption-type multi-material additive powder spreading system based on a micropore array, the powder dropping mechanism also includes an electrostrictive element, a reset member and a reset plate. The bracket is provided with a groove, the electrostrictive element is installed in the groove and is electrically connected to the control device, the ejector pin is connected to the end of the electrostrictive element, the reset plate is fixedly connected to the ejector pin, and the two ends of the reset member are respectively fixedly connected to the bracket and the reset plate; when powder spreading is required, the electrostrictive element is energized and drives the ejector pin to move toward the micropore, and the reset member is stretched to store elastic potential energy. When powder spreading is not required, the electrostrictive element is de-energized, and the reset member releases the elastic potential energy to drive the ejector pin to move away from the micropore.

[0012] In the above-mentioned adsorption-type multi-material additive powder laying system based on micropore array, the mesh screen is coaxially arranged with the bracket, the bracket is a hollow structure, and the first end of the bracket is connected to the vacuum pump, and the outer periphery of the other end has a plurality of air holes distributed in a circular array. When the vacuum pump is sucking, the gas flows through in sequence: the forming chamber, the micropores on the mesh screen, the air holes on the bracket, the interior of the bracket, and the vacuum pump.

[0013] The above-mentioned adsorption-type multi-material additive powder spreading system based on micropore array, the powder spreading device also includes a rotating shaft, a fixed seat, a top screw, a sleeve, a bearing, a first bearing seat, a first coupling and a rotating motor; the fixed seat, the first bearing seat and the rotating motor are all installed on the mobile platform, the bracket is connected to the fixed seat through a top screw, the rotating shaft is installed on the first bearing seat, and the rotating shaft is connected to the rotating motor through the first coupling, the mesh screen is fixedly connected to the sleeve, and the bearing is installed between the sleeve and the bracket.

[0014] The above-mentioned adsorption-type multi-material additive powder spreading system based on micropore array, the powder scraping device includes a slide and a scraper, the scraper is installed on the slide, and the slide can move relative to the screen along the X-axis, Y-axis and Z-axis directions to adjust the distance between the scraper and the screen.

[0015] The above-mentioned adsorption-type multi-material additive powder laying system based on micropore array also includes a moving mechanism. A fixed platform is provided in the forming chamber. The moving mechanism includes a linear guide, a second bearing seat, a ball screw, a nut seat, a second coupling, a moving motor and a linear slider. The moving motor and the second bearing seat are installed on the fixed platform, one end of the ball screw is connected to the second bearing seat, and the other end is connected to the moving motor through the second coupling. The moving platform is connected to the ball screw through the nut seat, and is connected to the linear guide through the linear slider.

[0016] The above-mentioned adsorption-type multi-material additive powder spreading system based on micropore array also includes a powder collecting bin, and a plurality of the powder collecting bins are provided, and the plurality of the powder collecting bins are correspondingly located below the plurality of the powder supply devices.

[0017] The present invention also provides an adsorption-type multi-material additive powder spreading system based on a micropore array, which is carried out using the above-mentioned adsorption-type multi-material additive powder spreading system based on a micropore array, and includes the following steps:

[0018] Step S1, according to the number of materials of the multi-material product, install a corresponding number of powder spreading devices, put different powder materials into each powder spreading device, adjust the distance between the powder scraping device and the mesh screen, turn on the system power, return each device to the origin, import the data of the multi-material product that has been sliced, start the gas circulation device, until the oxygen content in the forming chamber reaches the working level, and prepare for printing;

[0019] Step S2, turning on the vacuum pump to form a relative negative pressure inside the mesh screen, turning on the powder supply device, and rotating the mesh screen until the outer periphery of the mesh screen absorbs powder particles to form a powder layer, turning on the powder scraping device to scrape the powder layer on the outer periphery of the mesh screen, and the obtained powder layer thickness is the printed layer thickness;

[0020] Step S3, moving the mobile platform above the forming platform, keeping the mesh screen rotating, and using a powder dropping mechanism to spread powder particles on the periphery of the mesh screen, wherein when the mesh screen rotates one circle, the powder can just cover the corresponding powder spreading area, and according to the slicing data, during the powder spreading process, if the area needs to be spread with powder, the control device energizes the electrostrictive element, controls the ejector pin to move toward the mesh screen, and makes the curved surface of the ejector pin block the micropores of the mesh screen;

[0021] Step S4, after the powder spreading of the area is completed, if the next area still needs to be powdered, the power-on state of the electrostrictive element remains unchanged, the curved surface of the ejector pin is still attached to the inner surface of the mesh screen and blocks the micropores, so as to achieve continuous powder spreading; if the next area does not need to be powdered, the control device turns off the power of the electrostrictive element, and the reset element moves the ejector pin away from the mesh screen, so as to stop the powder spreading;

[0022] Step S5, multiple powder spreading devices work simultaneously, and driven by the moving mechanism, a layer of multi-material powder spreading of parts is achieved;

[0023] Step S6: using a laser device to irradiate and melt the laid powder to complete the manufacturing of a layer of parts;

[0024] Step S7, determining whether the multi-material product has been manufactured, if it has been completed, then the process ends, if it has not been completed, then executing step S8;

[0025] Step S8, lowering the forming platform by a layer thickness;

[0026] Step S9: The moving mechanism drives the powder spreading device to move in the reverse direction, and repeats steps S3 to S7.

[0027] This method uses the above-mentioned powder spreading system for powder spreading, and it has at least all the beneficial effects that the above-mentioned powder spreading system can bring. In addition, this powder spreading method controls the expansion and contraction of the electrostrictive element to drive the ejector pin to block the micropores on the mesh screen or open the micropores, thereby achieving continuous powder spreading or stopping powder spreading. Using multiple powder spreading devices to work simultaneously can achieve XY plane multi-material additive manufacturing, and then through the vertical movement of the forming platform, it can achieve Z direction multi-material additive manufacturing, and finally can achieve the manufacturing of parts with fully optimized performance.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a powder spreading system according to an embodiment of the present invention;

[0030] Figure 2 for Figure 1 The enlarged schematic diagram of point Ⅰ in the middle;

[0031] Figure 3It is an overall schematic diagram of the powder spreading device and the moving mechanism of an embodiment of the present invention;

[0032] Figure 4 for Figure 3 The enlarged schematic diagram of the middle II;

[0033] Figure 5 It is a schematic cross-sectional structure diagram of a powder spreading system according to an embodiment of the present invention;

[0034] Figure 6 It is a schematic diagram of the principle of adsorbing powder by the powder spreading system according to an embodiment of the present invention;

[0035] Figure 7a and Figure 7b A schematic diagram of the principle of laying powder by the powder laying system according to an embodiment of the present invention (single point);

[0036] Figure 8 A schematic diagram of the principle of laying powder by the powder laying system according to an embodiment of the present invention (lines and surfaces);

[0037] Fig. 9 A material distribution diagram of a certain layer of a multi-material product according to an embodiment of the present invention;

[0038] Fig.10 The multi-material product of the embodiment of the present invention Fig. 9 Material distribution diagram of the next layer adjacent to the material layer;

[0039] Fig.11 for Fig. 9 Schematic diagram of the slices of the material layer after computer processing;

[0040] Fig.12 for Fig.10 Schematic diagram of the slices of the material layer after computer processing;

[0041] Fig.13 The figure is a schematic diagram of the principle of computer data processing according to an embodiment of the present invention.

[0042] Description of the accompanying drawings: 1 forming chamber, 2 laser device, 3 moving mechanism, 4 first powder supply funnel, 5 first powder spreading device, 6 second powder supply funnel, 7 second powder spreading device, 8 third powder supply funnel, 9 third powder spreading device, 10 third powder bin, 11 second powder bin, 12 first powder bin, 13 multi-material product, 14 forming platform, 15 sixth powder bin, 16 fifth powder bin, 17 fourth powder bin, 18 fourth powder supply funnel, 19 fifth powder supply funnel, 20 sixth powder supply funnel, 21 fixed seat, 22 top screw, 23 mobile platform, 24 sleeve, 25 bearing, 26 rotating shaft, 27 first bearing seat, 28 first coupling, 29 rotating motor, 30 fixed platform, 31 linear guide, 32 second bearing seat, 33 ball screw, 34 nut seat, 35 second coupling, 36 mobile motor, 51 mesh screen, 52 micropore, 53 powder scraping device, 531 slide, 532 scraper, 54 vacuum pump, 55 electrostrictive element, 56 ejector pin, 57 reset member, 58 bracket, 59 reset plate, 60 control device, 70 gas circulation device, 80 signal line. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below. Figures 1 to 5 The embodiment of the present invention provides an adsorption-type multi-material additive powder spreading system based on a micropore array, comprising a forming chamber 1, a powder supply device and a powder spreading device. A forming platform 14 and a moving platform 23 are provided in the forming chamber 1. The forming platform 14 can be lifted and moved in the forming chamber 1 under the drive of a motor or other structure, and the moving platform 23 can move above the forming platform 14 for powder spreading. The powder supply device is arranged on the forming chamber 1 and is distributed in multiple numbers, and is used to provide powders of various materials. Furthermore, the powder supply device includes a powder supply funnel, such as Figure 1 As shown, six powder supply devices are provided, including the first powder supply funnel 4, the second powder supply funnel 6, the third powder supply funnel 8, the fourth powder supply funnel 18, the fifth powder supply funnel 19 and the sixth powder supply funnel 20. Among them, the first powder supply funnel 4, the second powder supply funnel 6, the third powder supply funnel 8 and the sixth powder supply funnel 20, the fifth powder supply funnel 19 and the fourth powder supply funnel 18 are symmetrically arranged on both sides of the forming chamber 1. The feeding port of the powder supply funnel penetrates into the forming chamber 1, and the neck of the powder supply funnel is provided with an electromagnetic valve, and the electromagnetic valve can be opened to add powder to the powder spreading device.

[0044] The powder spreading device is arranged on the mobile platform 23 and is distributed in multiple numbers, and the number is equal to the powder supply device on one side of the forming chamber 1. The mobile platform 23 is provided with multiple powder spreading windows, and the multiple powder spreading devices are correspondingly installed at the multiple powder spreading windows. During powder supply, a plurality of powder spreading devices are respectively located below a plurality of powder supply devices, each of which comprises a mesh screen 51, a vacuum pump 54 and a powder dropping mechanism. The mesh screen 51 is rotatably connected to the movable platform 23. The periphery of the mesh screen 51 has a plurality of polygonal micropores 52 distributed in a circular array. The inscribed circle diameter D1 of the micropore 52 is less than the outer diameter d of the powder particles and less than the circumscribed circle diameter D2 of the micropore 52. The vacuum pump 54 can draw from the inside of the mesh screen 51 to adsorb the powder particles dropped from the powder supply device onto the periphery of the mesh screen 51. The powder scraping device 53 is located on the side of the mesh screen 51, and is used to scrape off some of the powder particles on the periphery of the mesh screen 51 so that the powder thickness on the periphery of the mesh screen 51 reaches the desired thickness. The powder dropping mechanism is used to spread the powder particles on the periphery of the mesh screen 51 onto the forming platform 14.

[0045] The present powder spreading system is provided with a plurality of powder supply devices and a plurality of powder spreading devices. The plurality of powder supply devices can provide powders of various materials, and the plurality of powder spreading devices can spread powders of various materials, thereby preventing the powders from contaminating each other, meeting the additive manufacturing requirements of complex multi-material parts, and can be used to manufacture complex components with different material performance combinations. The present powder spreading system uses a mesh screen 51 and a vacuum pump 54 in coordination, which can evenly adsorb the powder particles on the periphery of the mesh screen 51, and the inscribed circle diameter D1 of the micropores 52 is less than the outer diameter d of the powder particles and less than the circumscribed circle diameter D2 of the micropores 52. Therefore, when the vacuum pump 54 draws suction inside the mesh screen 51, the powder particles will only be adsorbed on the periphery of the mesh screen 51, and will not pass through the micropores 52 and enter the interior of the mesh screen 51, and the powder particles will not completely cover the micropores 52, so that the airflow can still pass through the gap between the micropores 52 and the powder particles, thereby being able to In order to maintain the pressure difference between the inner and outer sides of the mesh screen 51, more powder particles can continue to be adsorbed, and then some powder particles are scraped off by the powder scraping device 53, and the thickness of the powder adsorbed on the periphery of the mesh screen 51 is accurately controlled. Finally, the powder spreading device is driven by the mobile platform 23 to move above the forming platform 14, and the powder dropping mechanism spreads the powder particles on the periphery of the mesh screen 51 onto the forming platform 14. A variety of powder materials can be evenly and accurately spread in the corresponding areas, solving the problem of accurately spreading different powders in one layer, and realizing XY plane multi-material additive manufacturing.

[0046] Further, refer to Figure 1The powder spreading system also includes a laser device 2, a control device 60 and a gas circulation device 70. The laser device 2 is arranged above the forming platform 14, and is used to emit a laser toward the forming platform 14 to melt the powder on the forming platform 14. The laser device 2 can adopt an existing conventional laser scanning galvanometer device, and the laser emitted by it can reach any position on the surface directly above the forming platform 14 to ensure that the powder at any position on the forming platform 14 can be melted by the laser. The control device 60 is electrically connected to the mobile platform 23, the powder supply device, the powder spreading device and the powder scraping device 53, and is used to control the working state of the mobile platform 23, the powder supply device, the powder spreading device and the powder scraping device 53. The gas circulation device 70 is used to provide an inert gas environment in the forming chamber 1 during operation to prevent the multi-material product 13 from being oxidized during the manufacturing process.

[0047] Further, continue to refer to Figure 1 The powder spreading system also includes a powder collecting bin, and there are multiple powder collecting bins, and the multiple powder collecting bins are correspondingly located below the multiple powder supply devices. When supplying powder, the powder spreading device is located between the powder supply funnel and the powder collecting bin. The width of the powder collecting bin is slightly larger than the diameter of the mesh screen 51, and is used to collect excess powder, which includes: powder thrown out when the mesh screen 51 rotates, powder that is not adsorbed on the mesh screen 51 by the air pressure difference, and powder scraped off the mesh screen 51 by the powder scraping device 53. After the powder spreading device receives and scrapes the powder between the powder supply funnel and the powder collecting bin, it is driven by the mobile platform 23 to the top of the forming platform 14 for spreading the powder. Furthermore, in the present embodiment, there are six powder collecting bins, namely the first powder collecting bin 12, the second powder collecting bin 11, the third powder collecting bin 10, the fourth powder collecting bin 17, the fifth powder collecting bin 16 and the sixth powder collecting bin 15, wherein the first powder collecting bin 12, the second powder collecting bin 11, the third powder collecting bin 10 and the sixth powder collecting bin 15, the fifth powder collecting bin 16 and the fourth powder collecting bin 17 are symmetrically arranged on both sides of the forming chamber 1. The number of powder collecting bins on either side of the forming chamber 1 is equal to the number of powder spreading devices, and each powder collecting bin is also arranged correspondingly under each powder supply funnel. For example, in the present embodiment, there are three powder spreading devices on the right side of the forming chamber 1, namely, a first powder spreading device 5, a second powder spreading device 7 and a third powder spreading device 9. When supplying and scraping powder, the first powder spreading device 5 is located below the first powder supply funnel 4, the first powder collecting bin 12 is located below the first powder spreading device 5, the second powder spreading device 7 is located below the second powder supply funnel 6, the second powder collecting bin 11 is located below the second powder spreading device 7, the third powder spreading device 9 is located below the third powder supply funnel 8, and the third powder collecting bin 10 is located below the third powder spreading device 9.

[0048] Further, refer to Figures 2 to 5The powder spreading device further includes a bracket 58, a rotating shaft 26, a fixed seat 21, a top screw 22, a sleeve 24, a bearing 25, a first bearing seat 27, a first coupling 28 and a rotating motor 29. The fixed seat 21, the first bearing seat 27 and the rotating motor 29 are all installed on the mobile platform 23. The bracket 58 is arranged inside the mesh screen 51, and the bracket 58 is connected to the fixed seat 21 through the top screw 22. The rotating shaft 26 is installed on the first bearing seat 27, and the rotating shaft 26 is connected to the rotating motor 29 through the first coupling 28. Figure 5 As shown, the two ends of the mesh 51 can be connected to the rotating shaft 26 and the sleeve 24 by screw connection or the like, and the bearing 25 is installed between the sleeve 24 and the bracket 58. Specifically, the bearing 25 is sleeved on the outer periphery of the bracket 58, and the sleeve 24 is sleeved on the outer periphery of the bearing 25. When the rotating motor 29 rotates, the rotating shaft 26, the sleeve 24 and the mesh 51 can be driven to rotate together, and because the bearing 25 isolates the motion transmission between the sleeve 24 and the bracket 58, and the top screw 22 can fix the bracket 58 on the fixed seat 21, the bracket 58 is kept in a stationary state.

[0049] Furthermore, the powder dropping mechanism includes an ejector pin 56, which is retractably connected to a bracket 58; the lower end of the ejector pin 56 has a curved surface, which can fit with the inner surface of the mesh screen 51 to block the micropores 52. Specifically, the curvature radius of the curved surface can be equal to the curvature radius of the inner surface of the mesh screen 51. When the curved surface at the lower end of the ejector pin 56 fits with the inner surface of the mesh screen 51, the curvature radii of the curved surface at the lower end of the ejector pin 56 and the inner surface of the mesh screen 51 at each fitting point are equal, so that the curved surface at the lower end of the ejector pin 56 can completely fit with the inner surface of the mesh screen 51 to prevent air leakage from affecting the powder spreading. When powder spreading is required, the ejector pin 56 can move inside the mesh 51 toward the micropore 52 so that the curved surface blocks the micropore 52, thereby reducing or eliminating the adsorption force on the powder particles, and the powder particles fall onto the forming platform 14 under the action of gravity. When powder spreading is not required, the ejector pin 56 can move away from the micropore 52 to open the micropore 52, thereby allowing the powder particles to be adsorbed to the periphery of the mesh 51. Furthermore, the powder dropping mechanism also includes an electrostrictive element 55, a reset member 57 and a reset plate 59. The bracket 58 is provided with a groove, the electrostrictive element 55 is installed in the groove and is electrically connected to the control device 60. The ejector pin 56 is connected to the end of the electrostrictive element 55, the reset plate 59 is fixedly connected to the ejector pin 56, and the two ends of the reset member 57 are respectively fixedly connected to the bracket 58 and the reset plate 59; when powder spreading is required, the electrostrictive element 55 is energized and drives the ejector pin 56 to move toward the micropore 52, and the reset member 57 is stretched to store elastic potential energy. When powder spreading is not required, the electrostrictive element 55 is de-energized, and the reset member 57 releases the elastic potential energy to drive the ejector pin 56 away from the micropore 52.

[0050] Furthermore, if Figure 2 and Figure 5As shown, the bracket 58 is divided into two parts, namely, a cylindrical part coaxial with the mesh 51 and a powder spreading part where the electrostrictive element 55 and the ejector pin 56 are placed. One end of the cylindrical part is connected to the vacuum pump 54, and the other end is provided with evenly distributed pores around it, and the pores are distributed in a circular array on the outer periphery of the cylindrical part. When the vacuum pump 54 sucks, the gas flows through the forming chamber 1, the micropores 52 on the mesh 51, the pores on the bracket 58, the inside of the bracket 58, and the vacuum pump 54 in sequence. The part of the bracket 58 with pores is coaxially arranged with the mesh 51, and these evenly distributed pores on the bracket 58 can ensure the uniformity of the air pressure inside the mesh 51, that is, on the side surfaces of each concentric cylinder of the mesh 51, the air pressure is consistent, so that the powder particles can be better ensured to be evenly adsorbed on the outer periphery of the mesh 51.

[0051] Furthermore, the mesh 51 is cylindrical in shape, a through hole is provided on the reset plate 59, the number of grooves on the bracket 58, the number of through holes on the reset plate 59, and the number of micropores 52 on the mesh 51 along the generatrix direction are the same, and the electrostrictive element 55 and the ejector pin 56 are used in combination, and the number is the same as the number of grooves on the bracket 58. The side surface of the mesh 51 is unfolded into a rectangle, and the area of ​​the unfolded rectangle is the same as the area of ​​the effective working area on the forming platform 14, and the length and width of the unfolded rectangle are correspondingly equal to the length and width of the effective working area on the forming platform 14.

[0052] like Figure 6 As shown, when working normally, the vacuum pump 54 draws the inside of the mesh 51 into a relatively negative pressure state. When the powder falls from the powder supply funnel, the air pressure difference presses the powder particles onto the mesh 51, and the inscribed circle diameter D1 of the micropore 52 is less than the outer diameter d of the powder particles and less than the circumscribed circle diameter D2 of the micropore 52, so the powder particles will not be sucked into the mesh 51, but stuck in the small holes. It can be understood that the micropore 52 is a hole with a circumscribed circle, such as a regular polygonal hole. Further, the micropore 52 is a square hole, and the cross-sectional side length of the square hole is less than the diameter of the smallest powder particle. In general, the shape of the powder particle can be considered to be an absolute sphere, and any cross-sectional shape thereof is circular. The cross-sectional shape of the micropore 52 is square, so the powder cannot completely cover the entire micropore 52, and the airflow can still pass through the gap between the micropore 52 and the powder particles, thereby maintaining the pressure difference to continuously adsorb more powder particles. Finally, through the scraping action of the powder scraping device 53, the thickness of the powder layer on the periphery of the mesh 51 reaches the required thickness.

[0053] Since the mesh 51 is in a rotating state when working, ignoring other minor factors, the outermost layer of powder attached to the mesh 51 is subjected to three forces in total, namely the gravity of the powder itself, the suction caused by the adsorption of the powder, and the contact force generated when it contacts the inner layer of powder, hereinafter referred to as gravity, suction and contact force. The thickness of the powder layer attached to the mesh 51 is determined by these three forces. It is easy to understand that as the thickness of the powder layer increases, the suction force on the outermost layer of powder continues to decrease. For powders with equal layer thickness, when the rotating motor 29 is working, the magnitude and direction of gravity remain unchanged, the magnitude of suction remains unchanged, the direction changes, and the magnitude and direction of the contact force change. Considering the outermost layer of powder at a certain busbar position of the mesh 51, the combined force of its gravity and suction can just provide the centripetal force required for circular motion. At this time, the contact force is zero, the powder is in a critical state, and the thickness of the powder layer is the smallest. Therefore, the thickness of the powder layer is not uniform on the outer surface of the entire mesh 51. Furthermore, whenever other positions on the mesh 51 are turned to this position, a certain amount of powder will fall off, and after leaving this position, it will have the ability to attract more powder again. Therefore, in the present invention, a powder scraping device 53 is installed to control the thickness of the powder layer on the mesh 51, so that the thickness of the powder layer on the mesh 51 reaches the required thickness, and the thickness is more uniform, which is conducive to improving the accuracy of subsequent powder spreading.

[0054] Further, refer to Figure 4 The powder scraping device 53 includes a slide 531 and a scraper 532. The scraper 532 is installed on the slide 531. The slide 531 can move relative to the mesh 51 along the X-axis, Y-axis and Z-axis directions to adjust the distance between the scraper 532 and the mesh 51. The scraper 532 includes two parts, namely a scraper bar and a main body for installing the scraper bar. The scraper bar has a cylindrical shape. The slide 531 has the freedom of movement in the three directions of X, Y and Z. After the scraper 532 is installed on the slide 531, the Z axis of the slide 531 is adjusted to make the axis of the scraper bar and the axis of the mesh 51 equal in height; the X axis of the slide 531 is adjusted to align the working surface of the scraper bar with the working surface of the mesh 51; the Y axis of the slide 531 is adjusted to change the distance between the scraper bar and the axis of the mesh 51. The difference obtained by subtracting the outer surface radius of the mesh 51 and the outer surface radius of the scraper bar from this distance is the thickness of the required powder layer, that is, the printing layer thickness.

[0055] Further, refer to Figure 3The movement of the mobile platform 23 is realized by the mobile mechanism 3. A fixed platform 30 is provided in the forming chamber 1. The mobile mechanism 3 includes a linear guide 31, a second bearing seat 32, a ball screw 33, a nut seat 34, a second coupling 35, a mobile motor 36 and a linear slider. The mobile motor 36 and the second bearing seat 32 are installed on the fixed platform 30. One end of the ball screw 33 is connected to the second bearing seat 32, and the other end is connected to the mobile motor 36 through the second coupling 35. The mobile platform 23 is connected to the ball screw 33 through the nut seat 34, and is connected to the linear guide 31 through the linear slider. When the mobile motor 36 is started, the ball screw 33 rotates, and the nut seat 34 thereon will move along the axial direction of the ball screw 33, thereby driving the mobile platform 23 on the nut seat 34 to move along the ball screw 33 and the linear guide 31.

[0056] like Figure 7a As shown, when powder needs to be spread, the control device 60 sends an electrical signal to the electrostrictive element 55, so that the electrostrictive element 55 extends outward, pushes the ejector pin 56 to slide outward, and stretches the reset member 57, that is, the spring, and moves the reset plate 59 downward. The bottom of the ejector pin 56 is a curved surface, and its cross-sectional size is slightly larger than the size of the micropore 52. Therefore, the ejector pin 56 can completely fit the inner surface of the mesh 51. At this time, the gas outside the mesh 51 quickly fills the gap between the powder particles in the micropore 52 and the surface of the ejector pin 56, so that the pressure difference on both sides of the powder disappears, and the powder at the micropore 52 is no longer under pressure. Under the action of gravity, the powder will fall on the forming platform 14 to achieve powder spreading. At this time, the powder at other positions is still adsorbed on the outer surface of the mesh 51 under the action of the pressure difference, and will not fall on the forming platform 14. Then, the moving mechanism 3 drives the powder spreading device to move forward and arrive at the next area. If this area still needs to be spread with powder, the control device 60 controls the electrostrictive element 55 to remain powered. As the rotary motor 29 rotates, the powder will be sent to the bottom of the ejector pin 56, so that the powder is no longer affected by the pressure difference and falls on the forming platform 14. Figure 7b As shown, if this area does not need to be spread with powder, the control device 60 stops sending electrical signals to the electrostrictive element 55. In the power-off state, the electrostrictive element 55 begins to retract, and the elastic potential energy previously stored in the reset member 57 is released. The retraction drives the reset plate 59 to move upward, thereby driving the ejector pin 56 and the electrostrictive element 55 to slide into the groove, and the lowermost curved surface of the ejector pin 56 is separated from the inner surface of the mesh 51. As the rotary motor 29 rotates, the powder sent to the bottom of the ejector pin 56 is still affected by the pressure difference and is adsorbed on the outer surface of the mesh 51, thereby stopping the spreading of powder.

[0057] like Figure 8As shown, the control device 60 is connected to the electrostrictive element 55 through a signal line 80. The control device 60 can independently control the power-on state of each electrostrictive element 55, thereby controlling the falling state of the powder particles under each ejector pin 56. Each time the control device 60 sends a signal, all the powder on the bottom busbar of the mesh 51 falls once as required, thereby completing the powder laying on the forming platform 14 corresponding to this straight line. Subsequently, the moving motor 36 moves forward one step, and the rotating motor 29 rotates one step in coordination. The corresponding relationship can be obtained from parameters such as the diameter of the mesh 51, the lead of the ball screw 33, and the transmission ratio of the mechanism. Then, the control device 60 sends a signal again to complete the powder laying on the next straight line, repeating multiple times to finally complete the powder laying in the corresponding area.

[0058] The present invention also provides an adsorption-type multi-material additive powder spreading system based on a micropore array, which is carried out using the above-mentioned adsorption-type multi-material additive powder spreading system based on a micropore array, and includes the following steps:

[0059] Step S1, according to the number of materials of the multi-material product 13, a corresponding number of powder spreading devices are installed, different powder materials are placed in each powder spreading device, the distance between the powder scraping device 53 and the mesh screen 51 is adjusted, the system power is turned on, each device returns to the origin, the data of the multi-material product 13 that has been sliced ​​is imported, and the gas circulation device 70 is started until the oxygen content in the forming chamber 1 reaches the working level, and it is ready for printing;

[0060] Step S2, start the vacuum pump 54 to form a relative negative pressure inside the mesh 51, turn on the powder supply device, and rotate the mesh 51 until the outer periphery of the mesh 51 absorbs powder particles to form a powder layer, and start the powder scraping device 53 to scrape the powder layer on the outer periphery of the mesh 51. The obtained powder layer thickness is the printed layer thickness;

[0061] Step S3, moving the mobile platform 23 above the forming platform 14, keeping the mesh 51 rotating, and using the powder dropping mechanism to spread the powder particles on the periphery of the mesh 51, wherein when the mesh 51 rotates one circle, the powder can just cover the corresponding powder spreading area, and according to the slicing data, during the powder spreading process, if the area needs to be spread with powder, the control device 60 energizes the electrostrictive element 55, controls the ejector pin 56 to move toward the mesh 51, and makes the curved surface of the ejector pin 56 block the micropores 52 of the mesh 51;

[0062] Step S4: After the powder spreading of the area is completed, if the next area still needs to be powdered, the power-on state of the electrostrictive element 55 remains unchanged, and the curved surface of the ejector pin 56 is still attached to the inner surface of the mesh 51 and blocks the micropores 52, so that continuous powder spreading is achieved. If the next area does not need to be powdered, the control device 60 turns off the power of the electrostrictive element 55, and the reset member 57 moves the ejector pin 56 away from the mesh 51, so that the powder spreading stops.

[0063] Step S5, multiple powder spreading devices work simultaneously, and driven by the moving mechanism 3, a layer of multi-material powder spreading of parts is achieved;

[0064] Step S6, using the laser device 2 to irradiate and melt the laid powder to complete the manufacturing of one layer of parts;

[0065] Step S7, determining whether the multi-material product 13 has been manufactured, if it has been manufactured, then the process ends, if it has not been manufactured, then executing step S8;

[0066] Step S8, lowering the forming platform 14 by a layer thickness;

[0067] Step S9, the moving mechanism 3 drives the powder spreading device to move in the reverse direction, and repeats steps S3 to S7.

[0068] It should be noted that in step S1, although the gas circulation device 70 provides inert gas to the forming chamber 1, in actual circumstances, whether printing can be started is determined based on the oxygen content to prevent oxidation of the material during the printing process, and the oxygen content can also be directly detected and displayed using corresponding measuring instruments. Therefore, in step S1, after turning on the gas circulation device 70, the oxygen content in the forming chamber 1 is monitored in real time until the oxygen content in the forming chamber 1 reaches the working level before preparing for printing.

[0069] Example

[0070] Reference Figures 9 to 13 According to the above-mentioned powder spreading system and powder spreading method, this embodiment provides a multi-material product 13 with three materials and is printed using SLM technology: assuming that each layer of the multi-material product 13 is composed of two or more materials, through computer processing, each layer can be divided into multiple printing areas according to the type of material, and all printing areas with the same material will form a material model with the same material. For example, in this example, the multi-material product 13 model can be composed of a first material, a second material, and a third material. For example, the first material is chromium-nickel-inconel 625 stainless steel powder, which is loaded in the first powder spreading device 5 before printing, the second material is CuSn10 powder, which is loaded in the second powder spreading device 7 before printing, and the third material is 316L powder, which is loaded in the third powder spreading device 9 before printing. Assuming that the thickness of the powder spreading layer is 30μm, it is set in the computer that the forming platform 14 drops 30μm after each layer of printing is completed. Since the price of 316L stainless steel powder is the lowest among the three metal powders, this powder is used as the filling material of the filling area.

[0071] Assume that the next two printing layers of the multi-material product 13 are as follows: Fig. 9 and Fig.10As shown, it includes a first printing layer 41 and a second printing layer 42, wherein the first printing layer 41 includes two areas 411 and 412, and the second printing layer 42 includes three areas 421, 422, and 423. After computer processing, the powder laying direction of each layer can be determined, such as Fig.11 and Fig.12 As shown, there are three areas in the first printing layer 41, namely 411, 412 and 413, of which 413 is a filling area; there are four areas in the second printing layer 42, namely 421, 422, 423 and 424, of which 424 is a filling area. The powder materials used in areas 413, 423 and 424 are the same, which are all 316L stainless steel powder in the third powder spreading device 9. According to the divided areas, the computer can obtain the scanning path of each area. Fig.13 As shown, since the powder spreading device can spread a line of powder at a time, the scanning path is a series of parallel line segments, where the spacing between the parallel line segments is determined by the arc length between the busbars where two adjacent micropores 52 of the mesh 51 are located, and the spacing is recorded as the step size, and then the line segment is simulated by a series of discrete points, where the distance between adjacent points in each line segment is determined by the distance between adjacent micropores 52 on a busbar of the mesh 51. Obviously, each small dot corresponds to an electrostrictive element 55. When the point is on the line segment, it is recorded as "1", and when the point is not on the line segment, it is recorded as "0". Obviously, "1" represents that the corresponding electrostrictive element 55 is in an energized state and needs to be spread with powder, and "0" represents that the corresponding electrostrictive element 55 is in an off state and does not need to be spread with powder. Obviously, Fig.13 It only shows the powder spreading data of one material in a layer. In this embodiment, there are three materials in total, so there are powder spreading data of three materials in a layer.

[0072] Further, assuming that the forming platform 14 has been lowered to the specified height, the first powder spreading device 5, the second powder spreading device 7 and the third powder spreading device 9 have all prepared the corresponding powder. For the first printing layer 41, the powder spreading device performs powder spreading from bottom to top. When the first powder spreading device 5 reaches the effective area of ​​the forming platform 14, its rotary motor 29 starts to rotate in coordination with the movement of the moving mechanism 3. At the same time, the control device 60 will send an electrical signal to the electrostrictive element 55 of the first powder spreading device 5 according to the slice data. Every time the mesh screen 51 of the first powder spreading device 5 rotates an arc length of a step, the control device 60 will send an electrical signal in sequence until the mesh screen 51 of the first powder spreading device 5 rotates one circle, and the control device 60 has just sent all the electrical signals related to the 411 area, thereby completing the powder spreading of the 411 area. While the first powder spreading device 5 is spreading powder, the rotating motor 29 of the second powder spreading device 7 remains stationary until the second powder spreading device 7 reaches the effective area of ​​the forming platform 14, at which time its rotating motor 29 begins to rotate in coordination with the movement of the moving mechanism 3, and at the same time, the control device 60 sends an electrical signal to the electrostrictive element 55 of the second powder spreading device 7 according to the slicing data. Every time the mesh screen 51 of the second powder spreading device 7 rotates an arc length of a step, the control device 60 sends an electrical signal in sequence until the mesh screen 51 of the second powder spreading device 7 rotates a circle, and the control device 60 just sends all the electrical signals related to the 412 area, thereby completing the powder spreading of the 412 area. While the first powder spreading device 5 and the second powder spreading device 7 are spreading powder, the rotating motor 29 of the third powder spreading device 9 remains stationary until the third powder spreading device 9 reaches the effective area of ​​the forming platform 14, at which time its rotating motor 29 begins to rotate in coordination with the movement of the moving mechanism 3, and at the same time, the control device 60 sends an electrical signal to the electrostrictive element 55 of the third powder spreading device 9 according to the slicing data. Every time the mesh 51 of the third powder spreading device 9 rotates by an arc length of a step, the control device 60 will send an electrical signal in sequence until the mesh 51 of the third powder spreading device 9 rotates one circle, and the control device 60 has just sent all the electrical signals related to the 413 area, thereby completing the powder spreading of the 413 area. The computer determines that the first printing layer 41 has completed the powder spreading of all areas, and the laser device 2, under the control of the computer instructions, completes the melting of the powder in the 411 and 412 areas. The computer determines that the first printing layer 41 is not the last layer, so the forming platform 14 drops 30μm.

[0073] Furthermore, the computer controls the first powder spreading device 5, the second powder spreading device 7 and the third powder spreading device 9 to complete the powder spreading of the second printing layer 42. For the second printing layer 42, the powder spreading device performs powder spreading from top to bottom. When the third powder spreading device 9 reaches the effective area of ​​the forming platform 14, its rotary motor 29 starts to rotate in coordination with the movement of the moving mechanism 3. At the same time, the control device 60 sends an electrical signal to the electrostrictive element 55 of the third powder spreading device 9 according to the slice data. Every time the mesh screen 51 of the third powder spreading device 9 rotates an arc length of a step, the control device 60 will send an electrical signal in sequence until the mesh screen 51 of the third powder spreading device 9 rotates one circle, and the control device 60 just sends all the electrical signals related to the 423 and 424 areas, thereby completing the powder spreading of the 423 and 424 areas. While the third powder spreading device 9 is spreading powder, the rotating motor 29 of the second powder spreading device 7 remains stationary until the second powder spreading device 7 reaches the effective area of ​​the forming platform 14, at which time its rotating motor 29 begins to rotate in coordination with the movement of the moving mechanism 3, and at the same time, the control device 60 sends an electrical signal to the electrostrictive element 55 of the second powder spreading device 7 according to the slicing data. Every time the mesh screen 51 of the second powder spreading device 7 rotates an arc length of a step, the control device 60 sends an electrical signal in sequence until the mesh screen 51 of the second powder spreading device 7 rotates a circle, and the control device 60 just sends all the electrical signals related to the 422 area, thereby completing the powder spreading of the 422 area. While the third powder spreading device 9 and the second powder spreading device 7 are spreading powder, the rotating motor 29 of the first powder spreading device 5 remains stationary until the first powder spreading device 5 reaches the effective area of ​​the forming platform 14, at which time its rotating motor 29 begins to rotate in coordination with the movement of the moving mechanism 3, and at the same time, the control device 60 sends an electrical signal to the electrostrictive element 55 of the first powder spreading device 5 according to the slicing data. Each time the mesh 51 of the first powder spreading device 5 rotates by an arc length of a step, the control device 60 will send an electrical signal in sequence until the mesh 51 of the first powder spreading device 5 rotates a circle and the control device 60 just sends all the electrical signals related to the 421 area, thereby completing the powder spreading of the 421 area. The computer determines that the second printing layer 42 has completed the powder spreading of all areas, and the laser device 2 completes the powder melting of the 421, 422 and 423 areas under the control of the computer instructions. If the second printing layer 42 is the last layer, the computer determines that the printing of the multi-material product 13 is completed. Otherwise, the forming platform 14 drops 30μm to prepare for the next printing.

[0074] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.

[0075] In the description of the present invention, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0076] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0077] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. An adsorption-type multi-material additive powder laying system based on a micropore array, characterized in that: It comprises a forming chamber (1), a powder supply device, a powder spreading device and a powder scraping device (53); A forming platform (14) and a moving platform (23) are provided in the forming chamber (1), and the moving platform (23) is capable of moving above the forming platform (14) to spread powder; The powder supply device is disposed on the forming chamber (1) and is distributed in plurality, and is used to provide powders of various materials; The powder spreading device is disposed on the mobile platform (23) and is distributed in plurality. When supplying powder, the plurality of powder spreading devices are respectively located below the plurality of powder supply devices. Each of the powder spreading devices comprises a mesh screen (51), a vacuum pump (54) and a powder dropping mechanism. The mesh screen (51) is rotatably connected to the mobile platform (23). The outer periphery of the mesh screen (51) has a plurality of polygonal micropores (52) distributed in a circular array. The inscribed circle diameter D1 of the micropores (52) is less than the outer diameter d of the powder particles and less than the diameter of the micropores (5 2), the vacuum pump (54) is capable of sucking from the inside of the mesh screen (51) to adsorb the powder particles dropped from the powder supply device onto the periphery of the mesh screen (51), the powder scraping device (53) is located on the side of the mesh screen (51) and is used to scrape off part of the powder particles on the periphery of the mesh screen (51) so that the powder thickness on the periphery of the mesh screen (51) reaches a desired thickness, and the powder dropping mechanism is used to spread the powder particles on the periphery of the mesh screen (51) onto the forming platform (14); The powder spreading device further comprises a bracket (58), the bracket (58) being arranged inside the mesh screen (51), the powder dropping mechanism comprising an ejector pin (56), the ejector pin (56) being telescopically connected to the bracket (58); The lower end of the ejector pin (56) has a curved surface. When powder spreading is required, the ejector pin (56) can move inside the mesh screen (51) toward the micropores (52) so that the curved surface blocks the micropores (52), thereby reducing or eliminating the adsorption force on the powder particles and causing the powder particles to fall onto the forming platform (14) under the action of gravity. When powder spreading is not required, the ejector pin (56) can move away from the micropores (52) to open the micropores (52), thereby allowing the powder particles to be adsorbed to the periphery of the mesh screen (51).

2. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 1 is characterized in that: It also includes a laser device (2), a control device (60) and a gas circulation device (70); The laser device (2) is arranged above the forming platform (14) and is used to emit laser light towards the forming platform (14) so ​​as to melt the powder on the forming platform (14); The control device (60) is electrically connected to the mobile platform (23), the powder supply device, the powder spreading device and the powder scraping device (53), and is used to control the working states of the mobile platform (23), the powder supply device, the powder spreading device and the powder scraping device (53); The gas circulation device (70) is used to provide an inert gas environment in the forming chamber (1) during operation.

3. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 2 is characterized in that: The powder dropping mechanism further comprises an electrostrictive element (55), a reset member (57) and a reset plate (59); the bracket (58) is provided with a groove, the electrostrictive element (55) is installed in the groove and is electrically connected to the control device (60); the ejector pin (56) is connected to an end of the electrostrictive element (55); the reset plate (59) is fixedly connected to the ejector pin (56); and both ends of the reset member (57) are respectively fixedly connected to the bracket (58) and the reset plate (59); When powder spreading is required, the control device (60) energizes the electrostrictive element (55) and drives the ejector pin (56) to move toward the micropore (52), and the reset member (57) is stretched to store elastic potential energy. When powder spreading is not required, the control device (60) de-energizes the electrostrictive element (55), and the reset member (57) releases elastic potential energy to drive the ejector pin (56) away from the micropore (52).

4. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 1 is characterized in that: The mesh screen (51) is coaxially arranged with the support (58); the support (58) is a hollow structure; a first end of the support (58) is connected to the vacuum pump (54); a second end of the support (58) has a plurality of air holes distributed in a circular array on its outer periphery; when the vacuum pump (54) is pumping, gas flows sequentially through: the forming chamber (1); the micropores (52) on the mesh screen (51); the air holes on the support (58); the interior of the support (58); and the vacuum pump (54).

5. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 1 is characterized in that: The powder spreading device further comprises a rotating shaft (26), a fixing seat (21), a top screw (22), a sleeve (24), a bearing (25), a first bearing seat (27), a first coupling (28) and a rotating motor (29); The fixed seat (21), the first bearing seat (27) and the rotating motor (29) are all mounted on the mobile platform (23); the bracket (58) is connected to the fixed seat (21) via a top screw (22); the rotating shaft (26) is mounted on the first bearing seat (27), and the rotating shaft (26) is connected to the rotating motor (29) via the first coupling (28); the end of the mesh screen (51) is fixedly connected to the sleeve (24); and the bearing (25) is mounted between the sleeve (24) and the bracket (58).

6. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 2, characterized in that: The powder scraping device (53) comprises a slide table (531) and a scraper (532); the scraper (532) is mounted on the slide table (531); the slide table (531) is movable relative to the mesh screen (51) along the X-axis, Y-axis and Z-axis directions to adjust the distance between the scraper (532) and the mesh screen (51).

7. The micropore array-based adsorption-type multi-material additive powder laying system according to claim 2, characterized in that: The present invention also comprises a moving mechanism (3), wherein a fixed platform (30) is provided in the forming chamber (1), and the moving mechanism (3) comprises a linear guide rail (31), a second bearing seat (32), a ball screw (33), a nut seat (34), a second coupling (35), a moving motor (36) and a linear slider, wherein the moving motor (36) and the second bearing seat (32) are mounted on the fixed platform (30), one end of the ball screw (33) is connected to the second bearing seat (32), and the other end is connected to the moving motor (36) via the second coupling (35), and the moving platform (23) is connected to the ball screw (33) via the nut seat (34), and is connected to the linear guide rail (31) via the linear slider.

8. The adsorption-type multi-material additive powder laying system based on micropore array according to claim 1, characterized in that: It also includes a powder collecting bin, and a plurality of the powder collecting bins are provided, and the plurality of the powder collecting bins are correspondingly located below the plurality of the powder supply devices.

9. An adsorption-type multi-material additive powder laying method based on a micropore array, characterized in that: The method is carried out using the adsorption-type multi-material additive powder laying system based on a micropore array as described in any one of claims 1 to 8, comprising the following steps: Step S1, according to the number of materials of the multi-material product (13), a corresponding number of powder spreading devices are installed, different powder materials are placed in each powder spreading device, the distance between the powder scraping device (53) and the mesh screen (51) is adjusted, the system power is turned on, each device returns to the origin, the data of the multi-material product (13) that has been sliced ​​is imported, and the gas circulation device (70) is started until the oxygen content in the forming chamber (1) reaches the working level, and printing is prepared; Step S2, turning on the vacuum pump (54) to form a relative negative pressure inside the mesh screen (51), turning on the powder supply device, and rotating the mesh screen (51) until the outer periphery of the mesh screen (51) absorbs powder particles to form a powder layer, turning on the powder scraping device (53) to scrape the powder layer on the outer periphery of the mesh screen (51), and the obtained powder layer thickness is the printed layer thickness; Step S3, moving the mobile platform (23) above the forming platform (14), keeping the mesh screen (51) rotating, and using a powder dropping mechanism to spread powder particles on the periphery of the mesh screen (51), wherein when the mesh screen (51) rotates one circle, the powder can just cover the corresponding powder spreading area, and according to the slicing data, during the powder spreading process, if the area needs to be spread with powder, the control device (60) energizes the electrostrictive element (55), controls the ejector pin (56) to move toward the mesh screen (51), and causes the curved surface of the ejector pin (56) to block the micropores (52) of the mesh screen (51); Step S4: After the powder spreading of the area is completed, if the next area still needs to be spread with powder, the power-on state of the electrostrictive element (55) remains unchanged, and the curved surface of the ejector pin (56) is still attached to the inner surface of the mesh screen (51) and blocks the micropores (52), thereby achieving continuous powder spreading. If the next area does not need to be spread with powder, the control device (60) turns off the power of the electrostrictive element (55), and the reset member (57) moves the ejector pin (56) away from the mesh screen (51), thereby stopping the powder spreading. Step S5, multiple powder spreading devices work simultaneously, and driven by the moving mechanism (3), a multi-material powder spreading of a layer of parts is achieved; Step S6, using the laser device (2) to irradiate and melt the laid powder to complete the manufacturing of a layer of parts; Step S7, determining whether the multi-material product (13) has been manufactured, if it has been manufactured, then the process ends; if it has not been manufactured, then executing step S8; Step S8, lowering the forming platform (14) by a layer thickness; Step S9: The moving mechanism (3) drives the powder spreading device to move in the reverse direction, and steps S3 to S7 are repeated.

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