Self-cleaning optical assembly and selective laser melting forming equipment

Abstract

The invention relates to a self-cleaning optical assembly and selective laser melting forming equipment, belongs to the technical field of additive manufacturing, and solves the problem that in the prior art, smoke dust generated in the metal powder melting process pollutes a laser window module. The self-cleaning optical assembly comprises a laser window module, a cyclone generator and an optical supporting plate. Wherein the laser window module is arranged at the top of a forming bin of the selective laser melting forming equipment through an optical supporting plate, and a laser beam is irradiated to a selective laser melting forming area through the laser window module; the cyclone generator is arranged between the laser window module and the optical supporting plate and can generate downward cyclone below the laser window module. The cyclone generator is adopted to generate downward annular airflow.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a self-cleaning optical component and laser selective melting forming equipment. Background Art

[0002] Laser selective melting forming technology selectively irradiates pre-spread metal powder by focusing a fine laser light source, and stacks it layer by layer into three-dimensional metal parts. Compared with traditional casting and forging technology, laser selective melting forming technology can obtain rapidly solidified non-equilibrium structure, small internal grains, excellent comprehensive mechanical properties, and can form parts with any complex structure. It provides new ideas for lightweight aircraft structure, topological optimization design and manufacturing, and has become an important development direction for advanced manufacturing in the aerospace field.

[0003] During the use of traditional laser selective melting forming equipment, the temperature of the molten pool generated when the laser energy is partially absorbed by the powder bed will exceed the boiling temperature of the powder material. Therefore, the temperature of the molten pool generated when the laser energy is locally absorbed by the powder bed will exceed the boiling temperature of the powder material. Then a vapor jet is formed on the surface of the molten pool, and the vaporized metal and entrained powder are ejected from the surrounding liquid molten pool particles. This vapor condenses into black smoke particles, and the entrained powder is partially gathered during the ejection. After the laser beam hits the powder bed, the smoke particles can reach the laser window module on the top of the molding chamber. When this happens, the smoke will contaminate the laser window module, resulting in a lower energy of the laser beam irradiated on the surface of the powder bed, which will seriously affect the printing quality and reduce the success rate of the equipment's prints. In order to solve this problem, the laser window module must be stopped and cleaned during the long-term operation of the laser selective melting forming equipment, which will in turn lead to a decrease in production efficiency. Summary of the invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a self-cleaning optical component and a laser selective melting forming device to solve the problem of smoke generated during the metal powder melting process polluting the laser window module in the prior art.

[0005] On the one hand, the present invention provides a self-cleaning optical component, including a laser window module, a cyclone generator and an optical support plate; the laser window module is arranged on the top of a forming chamber of a laser selective melting forming device through the optical support plate, and a laser beam is irradiated to the laser selective melting forming area through the laser window module; the cyclone generator is arranged between the laser window module and the optical support plate, and can generate a downward cyclone below the laser window module.

[0006] Furthermore, the cyclone generator comprises a first air inlet, an annular air inlet groove, a guide port, a cyclone guide channel and a bottom opening which are connected in sequence.

[0007] Furthermore, the gas enters the cyclone generator from the first air inlet, leaves the cyclone generator from the bottom opening, and forms a downward cyclone.

[0008] Furthermore, one or more first air inlets are provided.

[0009] Furthermore, a plurality of guide ports are provided, and the guide ports correspond one-to-one to the cyclone guide channels.

[0010] Furthermore, the sizes of the plurality of guide ports are different.

[0011] Furthermore, the closer the guide port is to the first air inlet, the smaller its size is.

[0012] Furthermore, the cyclone guide channel extends spirally downward.

[0013] Furthermore, the cross-sectional area of ​​the cyclone guide channel gradually decreases from top to bottom.

[0014] Furthermore, it also includes a cyclone air supply component, which can generate a downward airflow in the middle of the cyclone generator.

[0015] Furthermore, the cyclone air supply component is provided with a central opening and a second air inlet, and the second air inlet is evenly distributed along the circumference of the central opening.

[0016] Furthermore, the distance between the center of the middle opening and the center of the second air inlet is smaller than the inner diameter of the annular top plate of the cyclone generator and larger than the maximum outer diameter of the laser window module.

[0017] In another aspect, the present invention provides a selective laser melting forming device, comprising the self-cleaning optical component as described above.

[0018] Furthermore, it also includes a forming chamber and a forming substrate, wherein the forming substrate is arranged on the bottom plate of the forming chamber; a lateral air inlet is arranged on the side wall of one side of the forming chamber, and a lateral air outlet is arranged on the side wall of the opposite side.

[0019] Furthermore, the transverse air inlet and the transverse air outlet are provided in plurality and evenly distributed in the horizontal direction; or are concentratedly arranged in the middle of the side wall of the forming chamber, corresponding to the area range of the cyclone generated by the cyclone generator.

[0020] Furthermore, the lateral air inlet and the lateral air outlet are at the same height, and are arranged at a height of 5-15 mm from the upper surface of the forming substrate.

[0021] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0022] (1) The self-cleaning optical component of the present invention is designed to generate an annular airflow through a cyclone generator to prevent pollutants such as smoke generated during the melting process of metal powder from contaminating the laser lens, so that the laser window module of the continuously operating laser selective melting forming equipment can achieve a self-cleaning effect, providing favorable protection for the continuous operation of the laser selective melting forming equipment.

[0023] (2) The present invention can achieve a self-cleaning effect for the laser window module, ensuring that the laser window module is always in a clean state, ensuring that the energy of the laser beam irradiated on the powder bed is consistent, and ensuring the printing quality of the product.

[0024] (3) The self-cleaning optical component of the present invention can also use the downward airflow generated by the cyclone air replenishment component to replenish the blank area in the center of the cyclone, so that a continuous downward "cyclone vortex" is generated at the bottom of the laser window module, further improving the cleaning effect.

[0025] (4) The laser selective melting forming equipment of the present invention can form a horizontal air flow inside the forming chamber by arranging a horizontal air inlet and a horizontal air outlet on the side wall. The horizontal air flow can block the downward air flow vortex generated by the cyclone generator and the cyclone air supply component, thereby preventing these air flows from blowing metal dust to affect the forming process. At the same time, the smoke generated by the melting can be sent out of the forming chamber, further improving the cleaning effect.

[0026] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0028] Figure 1 It is a structural schematic diagram of a self-cleaning optical component according to Embodiment 1 of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the self-cleaning optical component of Example 1 of the present invention when viewed from the bottom;

[0030] Figure 3 is a cross-sectional schematic diagram of a self-cleaning optical component according to Example 1 of the present invention;

[0031] Figure 4The figure is a schematic diagram of the internal structure of the cyclone generator of the self-cleaning optical component of the present invention (without the annular top plate and inner wall);

[0032] Figure 5 It is a front view of the cyclone generator of the present invention;

[0033] Figure 6 for Figure 5 AA sectional view of the cyclone generator;

[0034] Figure 7 for Figure 5 AA section view of the cyclone generator (without the inner wall);

[0035] Figure 8 for Figure 5 A top view of a cyclone generator in FIG.

[0036] Fig. 9 It is a top view of a cyclone air supply component according to embodiment 2 of the present invention;

[0037] Fig.10 for Fig. 9 A BB-direction cross-sectional view of the cyclone air supply component;

[0038] Fig.11 It is a schematic assembly diagram of a self-cleaning optical component, a forming chamber and a forming substrate in a laser selective melting forming device according to Example 3 of the present invention;

[0039] Fig.12 Schematic diagram of the airflow direction in the forming chamber of Example 3 of the present invention.

[0040] Reference numerals:

[0041] 10-self-cleaning optical component; 11-laser output unit; 12-collimating mirror; 13-galvanometer; 14-laser window module; 15-cyclone air supply component; 151-second air inlet; 152-middle opening; 16-cyclone generator; 161-annular top plate; 162-first air inlet; 163-annular air inlet groove; 165-cyclone guide channel; 166-inner wall; 167-outer wall; 1671-outer cylindrical surface; 1672-annular step surface; 1673-outer conical surface; 168-spiral partition; 169-inner cylindrical surface; 1691-guide port; 164-bottom opening; 17-optical support plate; 20-forming chamber; 21-lateral air inlet; 22-lateral air outlet; 30-forming substrate. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] Example 1

[0044] This embodiment 1 provides a self-cleaning optical component 10, such as Figure 1-Figure 3 As shown, it includes a laser output unit 11, a collimating mirror 12, a galvanometer 13, a laser window module 14, a cyclone generator 16 and an optical support plate 17.

[0045] Among them, Figure 1 As shown, the laser output unit 11, the collimator 12, the galvanometer 13, and the laser window module 14 are connected in sequence and arranged on the top of the forming chamber 20 of the laser selective melting forming device through the optical support plate 17, so as to provide a laser beam for the laser selective melting forming. The laser window module 14 is used to output the laser beam required for the melting forming of the powder bed on the forming substrate 30 and the motion trajectory of the laser beam. During the operation of the laser selective melting forming device, the laser beam will be irradiated on the forming substrate 30 through the laser window module 14 to melt the powder, thereby generating residue and dust.

[0046] In this embodiment 1, a cyclone generator 16 is provided between the laser window module 14 and the optical support plate 17. The cyclone generator 16 is used to generate a downward cyclone below the laser window module 14 to prevent pollutants such as residues and dust generated during the melting of the metal powder from adhering to the laser window module 14.

[0047] The structure of the cyclone generator 16 is as follows: Figure 4-Figure 8 The cyclone generator 16 comprises an annular top plate 161 , an outer wall 167 , an inner wall 166 , an inner cylindrical surface 169 and a spiral partition 168 .

[0048] The annular top plate 161 is a flat plate in the shape of an annular ring and is located at the top of the cyclone generator 16 . The inner diameter of the annular ring is larger than the maximum outer diameter of the laser window module 14 , so that the laser window module 14 can be inserted from the center of the annular ring into the middle of the cyclone generator 16 .

[0049] like Figure 5 As shown, the outer wall 167 includes, from top to bottom, an outer cylindrical surface 1671, an annular step surface 1672 and an outer conical surface 1673, wherein the outer cylindrical surface 1671 extends vertically downward from the outer periphery of the annular top plate 161, the annular step surface 1672 extends radially inward in a horizontal plane from the bottom of the outer cylindrical surface 1671, and the outer conical surface 1673 extends obliquely inward and downward from the inner end of the annular step surface 1672.

[0050] See also Figure 6 The inner wall 166 is an inner conical surface, which extends downwardly from the inner side of the annular top plate 161 to a position close to the bottom of the outer conical surface 1673 .

[0051] See also Figure 7 The vertically extending inner cylindrical surface 169 is disposed between the annular step surface 1672 and the annular top plate 161. In a preferred embodiment, the inner diameter of the annular step surface 1672 is larger than the inner diameter of the annular top plate 161, and the inner cylindrical surface 169 extends vertically upward from the inner end of the annular step surface 1672, and its top is connected to the annular top plate 161.

[0052] See also Figure 4 , Figure 7 , Figure 8 A plurality of spiral baffles 168 are provided, uniformly distributed along the circumference of the cyclone generator 16. The spiral baffles 168 extend between the annular top plate 161, the inner cylindrical surface 169, the inner conical surface and the outer conical surface 1673, and divide the space enclosed by the above surfaces into a plurality of spiral cyclone guide channels 165.

[0053] The projection of the spiral partition 168 on the horizontal plane is as follows: Figure 8 As shown, the projection extends from the bottom opening 164 (i.e., the bottom of the outer conical surface 1673) along the curve to the inside of the inner cylindrical surface 169, and is tangent to the inner cylindrical surface 169. The curve formed by the projection is a part of a circle with the radius of the circle at the top of the inner wall 166 as the diameter. Through this arrangement, the radius of the airflow vortex formed can be minimized, thereby achieving the best cleaning effect. In addition, the diameter of the circle where the curve formed by the projection is located can be larger than the radius of the circle at the top of the inner wall 166. In this case, the radius of the cyclone will become larger, and the airflow blocking area formed will also become larger, but a blank area with no airflow will appear in the middle.

[0054] See also Figure 4 , a first air inlet 162 is provided on the outer cylindrical surface 1671, and the first air inlet 162 is connected to the air source. The annular top plate 161, the outer cylindrical surface 1671, the annular step surface 1672 and the inner cylindrical surface 169 enclose an annular groove, which is an annular air inlet groove 163. The first air inlet 162 is connected to the annular air inlet groove 163. Preferably, two or more first air inlets 162 can be provided, evenly distributed along the circumferential direction.

[0055] The inner cylindrical surface 169 is provided with a plurality of flow guide ports 1691, such as Figure 4 As shown, these guide ports 1691 are evenly distributed along the circumference of the inner cylindrical surface 169, and correspond one to one with the cyclone guide channel 165. In the preferred solution, the calibers of the guide ports 1691 are not equal. Specifically, the caliber of the guide port 1691 is proportional to the distance between the guide port 1691 and the first air inlet 162, that is, the closer the guide port 1691 is to the first air inlet 162, the smaller the caliber. Through this arrangement, the gas flow rate entering each guide port 1691 can be made roughly equal.

[0056] Each guide port 1691 is connected to a cyclone guide channel 165. The gas enters the annular air inlet groove 163 through the first air inlet 162, then enters the cyclone guide channel 165 through the guide port 1691, moves spirally downward along the cyclone guide channel 165, flows out from the bottom opening 164 of the cyclone generator 16, and forms a spiral downward airflow below the laser window module 14, preventing black smoke particles from adhering to the laser window module 14, and realizing self-cleaning of the optical system.

[0057] The optical support plate 17 is provided with a mounting hole. During assembly, the bottom of the cyclone generator 16 is inserted downwardly into the mounting hole from the top of the optical support plate 17. The annular step surface 1672 of the cyclone generator 16 is engaged with the upper surface of the optical support plate 17 and fixedly connected together. The laser window module 14 is inserted into the cyclone generator 16 from the middle of the annular top plate 161.

[0058] Further, see Figure 6 The inner conical surface and the outer conical surface 1673 have different vertex angles, and the vertex angle of the outer conical surface 1673 is greater than the vertex angle of the inner conical surface. This arrangement makes the cross-sectional area of ​​the cyclone guide channel 165 shrink faster along the gas flow direction, which is conducive to increasing the gas pressure, forming a faster cyclone flow rate, and better blocking the smoke and dust.

[0059] The vertex angle of the outer conical surface 1673 ranges from 65° to 70°, and the vertex angle of the inner conical surface ranges from 70° to 75°. The size of the vertex angles of the outer conical surface 1673 and the inner conical surface determines the speed direction of the cyclone. In the preferred embodiment, the lateral velocity component of the cyclone is greater than the vertical velocity component, so that the cyclone rotates faster to achieve a better barrier effect, and at the same time consumes most of the energy in the lateral rotational movement. When the airflow moves to the bottom of the forming chamber 20, the vertical velocity component is almost zero, which can better block the smoke and dust while not blowing metal dust downward to affect the forming effect.

[0060] Further, see Figure 3 The diameter of the bottom opening 164 of the cyclone generator 16 is greater than or equal to the maximum outer diameter of the laser window module 14. Generally, the diameter of the bottom opening 164 of the cyclone generator 16 is designed to be 1-1.5 times the maximum outer diameter of the laser window module 14, so that the "cyclone vortex" field can cover the entire laser window module 14. Such a setting can better protect the laser window module 14.

[0061] The distance from the bottom plane of the laser window module 14 to the bottom opening 164 of the cyclone generator 16 is between one tenth and one fifth of the diameter of the bottom opening 164. Through this setting, on the one hand, the laser window module 14 can be better protected, and on the other hand, the operation of the laser beam emitted by the laser window module 14 is not affected.

[0062] A self-cleaning optical component 10 of this embodiment 1 can form a whirlwind between the laser window module 14 and the metal powder melting area to block the smoke formed by the melting of the metal powder, thereby preventing the smoke from adhering to the laser window module 14 and affecting the forming quality.

[0063] Example 2

[0064] This embodiment 2 relates to a self-cleaning optical component 10, which, based on the embodiment 1, further includes a cyclone air supply component 15, which is used to provide a downward airflow in the middle of the cyclone generator 16 to provide supplementary protection for the blank area in the center of the cyclone generated by the cyclone generator 16.

[0065] See also Figure 9-10 The cyclone air supply member 15 is a flat plate structure, and a circular middle opening 152 is provided in the middle thereof for the laser window module 14 to pass through. Figure 1 , Figure 3 The cyclone air supply component 15 is arranged above the cyclone generator 16, and the two can be fixed by welding or other connection methods. The galvanometer 13 is arranged above the cyclone air supply component 15, and the laser window module 14 passes through the middle opening 152 from the bottom to the top and is fixedly connected to the galvanometer 13.

[0066] A second air inlet 151 is provided on each side of the central opening 152, and the second air inlet 151 is connected to the air source. Obviously, a plurality of second air inlets 151 can be provided, which are evenly distributed around the central opening 152. The distance between the center of the central opening 152 and the center of the second air inlet 151 is less than the inner diameter of the annular top plate 161 of the cyclone generator 16, and is greater than or equal to the maximum outer diameter of the laser window module 14. Preferably, the distance between the center of the central opening 152 and the center of the second air inlet 151 can make the airflow tangent to the maximum outer diameter position of the laser window module 14, that is, the second air inlet 151 is tangent to the projection of the laser window module 14 on the horizontal plane, because the closer to the center of the cyclone, the easier it is to form a vertically downward "cyclone vortex". The second air inlet 151 extends in the vertical direction. The airflow entering from the second air inlet 151 flows vertically downward, and after encountering the inner conical surface of the cyclone generator 16, it continues downward along the inner conical surface, and finally forms a downward airflow in the center of the cyclone generated by the cyclone generator 16, further blocking the smoke generated by the melting of the metal powder.

[0067] The airflow entering the first air inlet 162 and the airflow entering the second air inlet 151 are respectively controlled by air source air inlet valves. The flow rate of the airflow entering the first air inlet 162 is 15L / min, and the flow rate of the airflow entering the second air inlet 151 is 10L / min.

[0068] The self-cleaning optical component 10 of this embodiment can better prevent smoke and dust from contaminating the laser window module 14, thereby ensuring the quality of laser selective melting.

[0069] Example 3

[0070] This embodiment 3 relates to a laser selective melting forming device, which includes the self-cleaning optical component 10 of embodiment 1 or embodiment 2.

[0071] like Fig.11 As shown, the laser selective melting forming device further includes a forming chamber 20 and a forming substrate 30. The forming chamber 20 includes four side walls, a top plate and a bottom plate. The forming substrate 30 is arranged on the bottom plate of the forming chamber 20 for laying metal powder.

[0072] In this embodiment, a transverse air inlet 21 and a transverse air outlet 22 are respectively provided near the bottom of two opposite side walls of the forming chamber 20. The transverse air inlet 21 is connected to the air source and can provide a transverse airflow to the forming chamber 20. The transverse air outlet 22 is connected to the exhaust gas treatment device and can take the transverse airflow and smoke out of the forming chamber 20.

[0073] The lateral airflow can block the downward airflow vortex generated by the cyclone generator 16 and the cyclone air supply component 15, preventing these airflows from blowing metal dust to affect the forming process. At the same time, it can also send the smoke generated by melting out of the forming chamber 20, further improving the cleaning effect.

[0074] In a preferred solution, a plurality of transverse air inlets 21 and transverse air outlets 22 are provided, uniformly distributed in the horizontal direction, so as to form a partition layer to avoid turbulence affecting the cleaning effect.

[0075] In other embodiments, the transverse air inlet 21 and the transverse air outlet 22 can be centrally arranged in the middle of the side wall of the forming chamber 20, corresponding to the area of ​​the cyclone generated by the cyclone generator 16. This arrangement can avoid blowing metal powder in other areas that are not irradiated by the laser beam.

[0076] Furthermore, the heights of the lateral air inlet 21 and the lateral air outlet 22 are equal, and are set at a height of 5-15 mm from the upper surface of the forming substrate 30, which effectively avoids the influence of the "cyclone vortex" on the powder bed.

[0077] The laser selective melting forming device of the present invention can generate a downward airflow vortex, such as Fig.12 As shown, the upward smoke and dust during the printing process will be continuously blocked, and the surface of the laser window module will be continuously cleaned by airflow. In the center of the airflow vortex, a downward airflow can also be generated. In addition, a lateral airflow can also be generated. Based on the above airflow effects, the laser window module is always in a clean state, achieving continuous operation without stopping.

[0078] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A self-cleaning optical component, characterized in that: It comprises a laser window module, a cyclone generator and an optical support plate; the laser window module is arranged on the top of a forming chamber of a laser selective melting forming device through the optical support plate, and a laser beam is irradiated to a laser selective melting forming area through the laser window module; the cyclone generator is arranged between the laser window module and the optical support plate, and can generate a downward cyclone below the laser window module.

2. The self-cleaning optical component according to claim 1, characterized in that The cyclone generator comprises a first air inlet, an annular air inlet groove, a flow guide port, a cyclone flow guide channel and a bottom opening which are connected in sequence.

3. The self-cleaning optical component according to claim 2, characterized in that Gas enters the cyclone generator from the first air inlet, leaves the cyclone generator from the bottom opening, and forms a downward cyclone.

4. A self-cleaning optical component according to claim 2 or 3, characterized in that The first air inlet is provided with one or more.

5. A self-cleaning optical component according to claim 2 or 3, characterized in that A plurality of guide ports are provided, and the guide ports correspond to the cyclone guide channels one by one.

6. The self-cleaning optical component according to claim 5, characterized in that The sizes of the plurality of guide ports are different.

7. The self-cleaning optical component according to claim 6, characterized in that The closer the guide port is to the first air inlet, the smaller its size is.

8. A self-cleaning optical component according to claim 2 or 3, characterized in that The cyclone guide channel spirally extends downward.

9. The self-cleaning optical component according to claim 8, characterized in that The cross-sectional area of ​​the cyclone guide channel gradually decreases from top to bottom.

10. A laser selective melting forming device, characterized in that: A self-cleaning optical assembly comprising any one of claims 1-9.

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