Multi-material laser powder bed melting device based on pneumatic adsorption and forming process

Abstract

The invention relates to a multi-material laser powder bed melting device based on pneumatic adsorption and a forming process, the device comprises a laser unit, a feeding unit and a forming chamber, the lower part of the forming chamber is provided with a forming cavity and at least two powder cavities, the forming cavity is internally provided with a forming platform capable of moving up and down, the powder cavities are used for filling powder, and the forming platform is provided with a feeding unit. A lifting platform used for driving powder to move up and down is arranged in the powder cavity, the feeding unit is arranged in the forming chamber and comprises an adsorption face, the feeding unit is used for driving the adsorption face to move and / or rotate in the forming chamber, and when the adsorption face is located above the powder cavity and is away from the surface of the powder by a preset distance, the powder is fed into the powder cavity. The feeding unit is further used for applying negative pressure to the adsorption area of the adsorption face so that powder in the powder cavity can be adsorbed to the adsorption area of the adsorption face. Powder feeding is completed through pneumatic adsorption, the phenomenon of cross contamination of materials can be avoided, and the powder supply efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of additive manufacturing, and in particular to a multi-material laser powder bed melting device and a forming process based on pneumatic adsorption. Background Art

[0002] Laser powder bed fusion technology selectively melts metal powder layer by layer through a high-energy laser beam, and accurately builds a three-dimensional structure in the powder bed according to the preset CAD model. This technology breaks the traditional processing mode and can produce high-performance parts with complex structures, which has a wide range of application prospects.

[0003] Disadvantages:

[0004] Dual-material laser powder bed fusion technology can realize the integrated direct formability of bimetallic materials and customize the local performance or function of the same component. However, there are currently few dual-material printing solutions using laser powder bed fusion technology, and all of them have the phenomenon of large-scale mixing of materials, resulting in serious waste of powder. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a multi-material laser powder bed melting device and forming process based on pneumatic adsorption in view of the above shortcomings. The present invention completes the loading of powder through pneumatic adsorption, which can avoid the phenomenon of cross contamination of materials and improve the powder supply efficiency.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A multi-material laser powder bed melting device based on pneumatic adsorption includes a laser unit, a loading unit and a forming chamber.

[0008] The lower part of the forming chamber is provided with a forming cavity and at least two powder material cavities.

[0009] The forming cavity is provided with a forming platform which can move up and down.

[0010] The powder cavity is used to fill powder, and a lifting platform is provided in the powder cavity to drive the powder to move up and down.

[0011] The feeding unit is arranged in the forming chamber, and the feeding unit comprises an adsorption surface, and the feeding unit is used to drive the adsorption surface to move and / or rotate in the forming chamber. When the adsorption surface is located above the powder cavity and at a preset distance from the surface of the powder, the feeding unit is also used to apply negative pressure to the adsorption area of ​​the adsorption surface to adsorb the powder in the powder cavity on the adsorption area of ​​the adsorption surface; when the adsorption surface is located above the forming cavity and at a preset distance from the surface of the forming platform or the surface of the solidified powder layer, the feeding unit is also used to release the powder adsorbed on the adsorption surface.

[0012] The laser unit is used to melt the powder in the intended forming area of ​​the powder layer to be formed in the forming cavity by laser.

[0013] Furthermore, the feeding unit includes an adsorption head and a rotating / moving mechanism, wherein the adsorption head is arranged on the rotating / moving mechanism, and the rotating / moving mechanism is used to drive the adsorption head to move and / or rotate in the forming chamber.

[0014] The adsorption head is provided with an adsorption surface, and the adsorption head is externally connected to a negative pressure device, and the negative pressure device is used to apply negative pressure to the adsorption area of ​​the adsorption surface.

[0015] Furthermore, the rotating / moving mechanism can drive the adsorption head to move along one or more of the X-axis direction, the Y-axis direction and the Z-axis direction.

[0016] Furthermore, the adsorption surface is provided with a plurality of pores, the particle size of the pores is smaller than the particle size of the powder, and the negative pressure device can apply negative pressure at the pores.

[0017] Furthermore, the adsorption surface can cover the forming platform.

[0018] The multi-material laser powder forming process based on pneumatic adsorption includes the following steps:

[0019] Step S1, filling all powder cavities with powder, wherein the types of the powder are at least two;

[0020] Step S2, introducing an inert gas into the forming chamber to reduce the oxygen content in the forming chamber to a preset value;

[0021] Step S3, the adsorption head is driven to move to the top of the powder cavity by the rotating / moving mechanism, and is at a preset distance from the surface of the powder in the powder cavity, so that the pores in the adsorption area on the adsorption surface form a negative pressure to adsorb the powder in the powder cavity into the adsorption area of ​​the adsorption surface;

[0022] Step S4, the adsorption head is driven to move to the top of the forming cavity by the rotating / moving mechanism, and the distance from the surface of the forming platform or the surface of the uppermost solidified powder layer is preset, and all the pores in the adsorption area on the adsorption surface are converted from negative pressure to zero pressure, so as to unload the powder in the powder cavity onto the forming platform or the uppermost solidified powder layer;

[0023] Step S5, repeating steps S3 to S4 to form a powder material layer to be formed formed of multiple powder materials on the forming platform or the uppermost solidified powder material layer;

[0024] Step S6, the moving mechanism drives the adsorption head to reset;

[0025] Step S7, the laser unit applies laser to the intended forming area of ​​the powder material layer to be formed, so as to melt the powder in the intended forming area of ​​the powder material layer to be formed, so as to transform the powder material layer to be formed into a solidified powder material layer;

[0026] Step S8: the forming platform descends one layer, all the powder chambers ascend one layer, and steps S3 to S7 are repeated until the whole part is formed.

[0027] Furthermore, in step S3, the powder in the powder cavity is adsorbed in the adsorption area of ​​the adsorption surface, wherein the adsorption area of ​​the adsorption surface includes a pseudo-forming area and a non-pseudo-forming area.

[0028] Furthermore, before step S1, step S0 is also included, and step S0 is: importing the slicing data of the part into a control unit, and the control unit is used to analyze the slicing data and generate the intended forming area and non-intended forming area of ​​different materials of each layer of powder material to be formed according to the slicing data.

[0029] After adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0030] (1) The present invention can realize integrated additive manufacturing of multi-material structural parts;

[0031] (2) In the present invention, powders of different materials only come into contact in the forming cavity to avoid mixing of different materials;

[0032] (4) In the present invention, there is no need to use a powder spreading vehicle or a scraper to spread the powder, which can improve the powder supply efficiency.

[0033] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the structure of a device according to Embodiment 1 of the present invention;

[0035] Figure 2 It is a structural schematic diagram of the adsorption surface of the adsorption head of the present invention;

[0036] Figure 3 It is the adsorption principle diagram of the present invention;

[0037] Figure 4 Schematic diagram of dual-material powder supply of the present invention, wherein (a) is Example 1 and (b) is Example 2.

[0038] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0039] 1. Laser unit; 2. Loading unit; 2a. Adsorption surface; 2b. Air hole; 21. Adsorption head; 22. Rotation / movement mechanism; 3. Forming chamber; 4. Forming cavity; 41. Forming platform; 5. Powder cavity; 51. Lifting platform; 5a. First powder cavity; 5b. Second powder cavity. DETAILED DESCRIPTION

[0040] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise" and "counterclockwise" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0042] Embodiment 1:

[0043] This embodiment takes a dual-material laser powder bed melting device and forming process as an example.

[0044] like Figure 1 As shown, in this embodiment, a forming cavity 4 and two powder cavities 5 are provided at the bottom of the forming chamber 3. The two powder cavities 5 are respectively arranged on both sides of the forming cavity 4, and the forming cavity 4 and the two powder cavities 5 are distributed on the same straight line (X axis). The two powder cavities 5 are respectively a first powder cavity 5a and a second powder cavity 5b. The first powder cavity 5a and the second powder cavity 5b are respectively used to fill A powder and B powder. A powder and B powder are powders of different materials.

[0045] The feeding unit 2 includes an adsorption head 21, an X-moving mechanism and a Z-moving mechanism. The adsorption head 21 is arranged on the Z-moving mechanism, and the Z-moving mechanism is arranged on the X-moving mechanism. The X-moving mechanism is used to drive the adsorption head 21 to move along the X-axis direction to move between the forming cavity 4 and the two powder cavities 5; the Z-moving mechanism is used to drive the adsorption head 21 to move along the Z-axis direction (i.e., rise or fall), and the distance between the adsorption surface 2a and the surface of the forming platform 41 or the surface of the powder layer to be formed or the surface of the powder in the powder cavity 5.

[0046] In this embodiment, since the powder cavity 5 and the forming cavity 4 are distributed on the X-axis, the adsorption head 21 does not need to move along the Y-axis, and generally, the adsorption head 21 does not need a rotation function, which is also omitted in this embodiment.

[0047] like Figure 2As shown, the adsorption surface 2a of the adsorption head 21 is covered with dense pores 2b, and the aperture of the pores 2b is smaller than the minimum particle size of the powder (about 20mm); Figure 3 As shown, the adsorption head 21 is externally connected to a negative pressure device, and negative pressure is applied to the pores by the negative pressure device to adsorb the powder at the bottom of the pores 2b.

[0048] In this embodiment, the shape of the adsorption head 21 is rectangular, and the cross-sectional shapes of the forming cavity 4, the first powder cavity 5a, and the second powder cavity 5b are also rectangular. The adsorption surface 2b can cover the forming platform 41 (that is, the cross-sectional shape and size of the adsorption head 21 are larger than the cross-sectional shape and size of the forming cavity 4).

[0049] The forming process based on the above device includes the following steps:

[0050] (1) Importing the slice data of the part to be formed into an industrial computer (control unit), analyzing the slice data of the part by the industrial computer, and generating the intended forming area and non-intended forming area of ​​the A powder material and the B powder material of each layer of the powder material to be formed;

[0051] (2) Powder A and powder B are respectively filled into the first powder cavity 5a and the second powder cavity 5b;

[0052] (3) introducing an inert gas into the molding chamber 3 until the oxygen content in the molding chamber 3 drops to 100 ppm;

[0053] (4) The adsorption head 21 is driven to move above the first powder chamber 5a along the X-axis direction by the X-moving mechanism, and then the adsorption head 21 is driven to move along the Z-axis direction by the Z-moving mechanism until the adsorption surface 2b contacts the A powder;

[0054] (5) Figure 4 (a) or Figure 4 As shown in (b), the pores in the A adsorption area (i.e., the intended forming area and the non-intended forming area of ​​the A powder) on the adsorption surface 2a form a negative pressure to adsorb the A powder in the first powder cavity 5a into the A adsorption area of ​​the adsorption surface 2a;

[0055] (6) After the adsorption head 21 has adsorbed the A powder, the X-moving mechanism drives the adsorption head 21 to move above the forming cavity 4 along the X-axis direction, and then the Z-moving mechanism drives the adsorption head 21 to move along the Z-axis direction until the A powder on the adsorption surface 2b contacts the forming platform 41 or the uppermost solidified powder layer, and then the air holes in the A adsorption area on the adsorption surface 2a are turned from negative pressure to zero pressure, so that the A powder on the adsorption surface 2a is unloaded in situ onto the forming platform 41 or the uppermost solidified powder layer;

[0056] (7) The adsorption head 21 is driven to move above the second powder chamber 5b along the X-axis direction by the X-moving mechanism, and then the adsorption head 21 is driven to move along the Z-axis direction by the Z-moving mechanism until the adsorption surface 2b contacts the B powder;

[0057] (8) Figure 4 (a) or Figure 4 As shown in (b), the pores in the B adsorption area (i.e., the intended forming area and the non-intended forming area of ​​the B powder) on the adsorption surface 2a form a negative pressure to adsorb the B powder in the second powder cavity 5b into the B adsorption area of ​​the adsorption surface 2a;

[0058] (9) After the adsorption head 21 has adsorbed the B powder, the X-moving mechanism drives the adsorption head 21 to move above the forming cavity 4 along the X-axis direction, and then drives the adsorption head 21 to move along the Z-axis direction through the Z-moving mechanism until the B powder on the adsorption surface 2b contacts the forming platform 41 or the uppermost solidified powder layer, and then the air holes in the B adsorption area on the adsorption surface 2a are turned from negative pressure to zero pressure, so that the B powder on the adsorption surface 2a is unloaded in situ onto the forming platform 41 or the uppermost solidified powder layer;

[0059] (10) Powder A and powder B form a powder layer to be formed on the forming platform 41 or the uppermost solidified powder layer, and the X-moving mechanism and the Z-moving mechanism drive the adsorption head 21 to reset;

[0060] (11) The laser unit 1 is started, and the laser selectively melts the powder in the intended forming area of ​​the powder layer to be formed, so that the powder in the intended forming area of ​​the layer is solidified to obtain a solidified powder layer;

[0061] (12) The forming platform 41 descends one layer, and the lifting platforms 51 of the first powder chamber 5a and the second powder chamber 5b ascend one layer, and steps (4) to (11) are repeated until the integral forming of the part is completed.

[0062] In the above-mentioned forming process, the A adsorption area and the B adsorption area both include a simulated forming area and a non-simulated forming area of ​​the powder (the non-simulated forming area is the powder bed area), wherein the simulated forming area is related to the slicing data of the part to be formed, and the non-simulated forming area is related to the area of ​​the forming platform 41 (that is, the cross-section of the forming cavity) and the slicing data of the part to be formed.

[0063] In this embodiment, when the adsorption head 21 contacts the powder, the Z moving mechanism can drive the adsorption head 21 to further descend to level the surface of the powder in the powder chamber 5, so that there is no need to use a scraper or a powder spreading vehicle for leveling, thereby greatly improving the powder supply efficiency.

[0064] Embodiment 2:

[0065] In this embodiment, the number of powder cavities 5 is greater than two, and the powder cavities 5 are distributed on the peripheral side of the forming cavity 4. In this case, the rotating / moving mechanism 2 needs to add a Y axis. Therefore, in this embodiment, the rotating / moving mechanism 2 includes an X moving mechanism, a Y moving mechanism and a Z moving mechanism. The adsorption head 21 is arranged on the Z moving mechanism, the Z moving mechanism is arranged on the X moving mechanism, and the X moving mechanism is arranged on the Y moving mechanism. The Z moving mechanism is used to drive the adsorption head to move along the Z axis direction, the X moving mechanism is used to drive the adsorption head to move along the X axis direction, and the Y moving mechanism is used to drive the adsorption head to move along the Y axis direction.

[0066] Furthermore, when there is an angular offset between the powder chamber 5 and the forming chamber 4, the rotating / moving mechanism 2 needs to increase the ability to drive the adsorption head 21 to rotate in the XY plane. Therefore, in this embodiment, a rotating platform is provided on the moving end of the Z moving mechanism, and the adsorption head 21 is provided on the rotating platform. The rotating platform is used to drive the adsorption head 21 to rotate in the XY plane.

[0067] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. A multi-material laser powder bed melting device based on pneumatic adsorption, characterized in that: It comprises a laser unit (1), a loading unit (2) and a forming chamber (3), The lower part of the forming chamber (3) is provided with a forming cavity (4) and at least two powder material cavities (5). The forming cavity (4) is provided with a forming platform (41) which can move up and down. The powder cavity (5) is used to fill powder, and a lifting platform (51) is provided in the powder cavity (5) for driving the powder to move up and down. The feeding unit (2) is arranged in the forming chamber (3), and the feeding unit (2) comprises an adsorption surface (2a). The feeding unit (2) is used to drive the adsorption surface (2a) to move and / or rotate in the forming chamber (3). When the adsorption surface (2a) is located above the powder cavity (5) and at a preset distance from the surface of the powder, the feeding unit (2) is also used to apply negative pressure to the adsorption area of ​​the adsorption surface (2a) so as to adsorb the powder in the powder cavity (5) on the adsorption area of ​​the adsorption surface (2a); when the adsorption surface (2a) is located above the forming cavity (4) and at a preset distance from the surface of the forming platform (41) or the surface of the solidified powder layer, the feeding unit (2) is also used to release the powder adsorbed on the adsorption surface (2a). The laser unit (1) is used to melt the powder in the intended forming area of ​​the powder layer to be formed in the forming cavity (4) by laser.

2. The multi-material laser powder bed melting device based on pneumatic adsorption according to claim 1 is characterized in that: The loading unit (2) comprises an adsorption head (21) and a rotating / moving mechanism (22), wherein the adsorption head (21) is arranged on the rotating / moving mechanism (22), and the rotating / moving mechanism (22) is used to drive the adsorption head (21) to move and / or rotate in the forming chamber (3). The adsorption head (21) is provided with an adsorption surface (2a), and the adsorption head (21) is externally connected to a negative pressure device, and the negative pressure device is used to apply negative pressure to the adsorption area of ​​the adsorption surface (2a).

3. The multi-material laser powder bed melting device based on pneumatic adsorption according to claim 2 is characterized in that: The rotating / moving mechanism (22) can drive the adsorption head (21) to move along one or more of the X-axis direction, the Y-axis direction and the Z-axis direction.

4. The multi-material laser powder bed melting device based on pneumatic adsorption according to claim 2 is characterized in that: The adsorption surface (2a) is provided with a plurality of pores (2b), the particle size of the pores (2b) is smaller than the particle size of the powder, and the negative pressure device can apply negative pressure at the pores (2b).

5. The multi-material laser powder bed melting device based on pneumatic adsorption according to claim 1 is characterized in that: The adsorption surface (2a) can cover the forming platform (41).

6. Multi-material laser powder forming process based on pneumatic adsorption, characterized in that: The following steps are involved: Step S1, filling all powder material chambers (5) with powder materials, wherein the types of the powder materials are at least two; Step S2, introducing an inert gas into the forming chamber (3) to reduce the oxygen content in the forming chamber (3) to a preset value; Step S3, driving the adsorption head (21) to move to the top of the powder cavity (5) by the rotating / moving mechanism (22), and to a preset distance from the surface of the powder in the powder cavity (5), so that the pores (2b) in the adsorption area on the adsorption surface (2a) form a negative pressure, so that the powder in the powder cavity (5) is adsorbed in the adsorption area of ​​the adsorption surface (2a); Step S4, driving the adsorption head (21) to move to the top of the forming cavity (4) by the rotating / moving mechanism (22), and to a preset distance from the surface of the forming platform (41) or the surface of the uppermost solidified powder layer, so that all the pores (2b) in the adsorption area on the adsorption surface (2a) are converted from negative pressure to zero pressure, so as to unload the powder in the powder cavity (5) onto the forming platform (41) or the uppermost solidified powder layer; Step S5, repeating steps S3 to S4 to form a powder material layer to be formed consisting of a plurality of powder materials on the forming platform (41) or the uppermost solidified powder material layer; Step S6, the moving mechanism drives the adsorption head (21) to reset; Step S7, the laser unit (1) applies laser to the intended forming area of ​​the powder material layer to be formed, so as to melt the powder in the intended forming area of ​​the powder material layer to be formed, so as to transform the powder material layer to be formed into a solidified powder material layer; Step S8: the forming platform (41) descends one layer, all the powder chambers (5) ascend one layer, and steps S3 to S7 are repeated until the integral part is formed.

7. The multi-material laser powder forming process based on pneumatic adsorption according to claim 6 is characterized in that: In step S3, the powder in the powder cavity (5) is adsorbed into the adsorption area of ​​the adsorption surface (2a), wherein the adsorption area of ​​the adsorption surface (2a) includes a pseudo-forming area and a non-pseudo-forming area.

8. The multi-material laser powder forming process based on pneumatic adsorption according to claim 7 is characterized in that: Before step S1, step S0 is also included, and step S0 is: importing the slicing data of the part into a control unit, and the control unit is used to analyze the slicing data and generate the proposed forming area and the non-planned forming area of ​​different materials of each layer of powder material to be formed according to the slicing data.

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