Powder cleaning method for thin-wall part of cavity structure based on laser powder bed melting additive manufacturing

Abstract

The invention discloses a powder cleaning method for a thin-wall part of a cavity structure based on laser powder bed melting additive manufacturing, and belongs to the technical field of powder bed melting additive manufacturing. The powder cleaning method comprises the following steps that based on the laser powder bed melting additive manufacturing technology, a supporting mechanism is arranged in the cavity structure, and the cavity structure is supported by the supporting mechanism; the thin-wall part with a cavity structure is manufactured, and a fluid flowing channel used for communicating the interior of the cavity structure of the thin-wall part with the exterior of the thin-wall part is arranged on the supporting mechanism; a plurality of powder discharging holes are formed in the thin-wall part, threaded structures used for being connected with the outside are arranged in the powder discharging holes, and the fluid circulation channel communicates with the outside of the thin-wall part through the powder discharging holes. A thin-wall part provided with a powder discharging hole is installed on a base plate of a rotating table, a powder suction pipe and a plurality of powder blowing pipes are installed according to the position of the powder discharging hole, powder remaining in a cavity of the part can be cleaned after a powder bed is melted, the influence of residual powder agglomeration or caking caused by subsequent heat treatment is avoided, and the powder feeding efficiency is improved. The part forming quality is ensured; and the part performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder bed fusion additive manufacturing, and in particular to a powder cleaning method for manufacturing thin-walled parts with cavity structures based on laser powder bed fusion additive manufacturing. Background Art

[0002] Powder bed fusion is a widely used manufacturing technology in additive manufacturing. It uses laser or electron beam as heat source and processes discrete materials in a layer-by-layer manner through the three-dimensional sheet model in computer software. This technology can directly form metal parts close to full density. Compared with traditional processing technology, the overall utilization rate of materials is high and the cycle is short. It can form freely designed and manufactured complex structural parts. Therefore, this technology has good market prospects and broad application prospects in the fields of aerospace, medical and so on.

[0003] Powder bed fusion technology is an important technology in additive manufacturing. It uses the laser emitted by the laser to melt metal powder in a program-edited order. After each layer of powder is laid, the molten layer solidifies and is continuously superimposed to finally produce a molded part. The forming of cavity structures is of great significance for the lightweight of parts and products, and additive manufacturing technology is particularly suitable for the forming of cavity structures. At present, there are the following problems: In the current design process of thin-walled cavity structures based on additive manufacturing technology, it is necessary to add a self-supporting structure to the inside of the thin-walled cavity structure for forming, and the internal cavity is too large, which can easily cause the surface of the formed cavity to produce surface unevenness due to stress, thereby affecting the surface forming accuracy;

[0004] After the parts are formed, the excess powder in the cavity needs to be cleaned and recovered in the equipment cabin. However, since the parts are formed on the substrate and the substrate is connected to the equipment cabin by bolts, it cannot be flipped and moved. For small parts without cavities, the powder can be cleaned in the cabin, but with complex cavity structures, it is difficult to completely clean the powder inside the cavity. If the powder is not completely cleaned, it may affect the subsequent heat treatment. In addition to the fact that the excess powder may affect the vacuum pump of the vacuum heat treatment, the residual powder inside the part may agglomerate during the subsequent heat treatment, thereby affecting the performance and quality of the part. Therefore, it is necessary to design a powder cleaning method for thin-walled parts with cavity structures manufactured based on laser powder bed melting additive manufacturing. Summary of the invention

[0005] The object of the present invention is to provide a powder cleaning method for manufacturing thin-walled parts with cavity structures based on laser powder bed fusion additive manufacturing, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a powder cleaning method for thin-walled parts with cavity structures manufactured based on laser powder bed fusion additive manufacturing, comprising the following steps:

[0007] S1. Based on the laser powder bed fusion additive manufacturing technology, a thin-walled part having a cavity structure is manufactured by providing a support mechanism inside the cavity structure, wherein the support mechanism is provided with a fluid flow channel for connecting the inside of the cavity structure of the thin-walled part and the outside of the thin-walled part;

[0008] S2. A plurality of powder discharge holes are provided on the thin-walled member, wherein the powder discharge hole is provided with a threaded structure for connecting with the outside, and the fluid flow channel is connected with the outside of the thin-walled member through the powder discharge hole;

[0009] S3. The thin-walled part with the powder discharge hole is installed on the base plate of the rotating table, the base plate is in a horizontal position, and a powder suction pipe and a plurality of powder blowing pipes are installed according to the positions of the powder discharge holes, so that the powder blowing device is connected with the thin-walled part through the powder blowing pipe, and the powder suction device is connected with the thin-walled part through the powder suction pipe. The total number of the powder suction pipes and the powder blowing pipes is equal to the number of the powder discharge holes. The powder suction pipe and the powder blowing pipe are both provided with threaded joints that match the threaded structure of the powder discharge holes. The thin-walled part is a part with the largest cross section as the symmetry plane, and the rotating axis of the rotating table and the largest cross section of the thin-walled part are in the same plane;

[0010] S4. Drive the rotating table to rotate around the rotating axis by a preset angle, turn on the powder blowing device and the powder sucking device to perform a powder cleaning operation, turn off the powder blowing device and the powder sucking device after the preset time is reached, drive the rotating table to rotate around the rotating axis in the opposite direction by twice the preset angle, then turn on the powder blowing device and the powder sucking device to perform a powder cleaning operation, turn off the powder blowing device and the powder sucking device after the preset time is reached, and reset the substrate to a horizontal state;

[0011] S5. Disconnect the powder suction pipe from the corresponding exhaust hole, disconnect one of the powder blowing pipes from the corresponding exhaust hole, connect the powder suction pipe to the exhaust hole corresponding to the powder blowing pipe, connect the powder blowing pipe to the powder exhaust hole corresponding to the powder suction pipe, and repeat step S4 until the last powder blowing pipe and the powder suction pipe are interchanged;

[0012] S6. Disconnect the powder suction pipe that has completed the last position exchange from the corresponding exhaust hole, and check whether there is residual powder at the powder exhaust hole connected to the powder suction pipe. If there is, continue to repeat steps S4 and S5 until the powder cleaning is completed.

[0013] In a further embodiment, in step S1, the supporting mechanism is a rib structure retained within the boundary trajectory after Boolean operation between a honeycomb structure formed by ribs and a boundary trajectory formed at the maximum cross-section of the cavity, the rib structure and the inner wall of the cavity form a plurality of closed chambers, and the fluid flow channel connects the plurality of closed chambers.

[0014] In a further embodiment, in step S3, the powder blowing device is a gas pressure storage tank, and the powder suction device is a vacuum cleaner.

[0015] In a further embodiment, in step S4, the preset angle is 30-60 degrees, and the preset time is 5-15 minutes.

[0016] In a further embodiment, the preset angle is 45 degrees, and the preset time is 10 minutes.

[0017] In a further embodiment, in step S1, the maximum distance of the cavity perpendicular to the maximum cross-section of the thin-walled member is 50 mm, and the minimum distance of the cavity perpendicular to the maximum cross-section of the thin-walled member is 3 mm.

[0018] In a further embodiment, in step S2, the number of the powder discharge holes is 4-6.

[0019] In a further embodiment, in step S3, the diameters of the powder suction pipe and the powder blowing pipe are larger than the diameter of the powder discharge hole by 1-2 mm.

[0020] In a further embodiment, in the step S3, a channel for the powder suction pipe and the powder blowing pipe to pass through is opened on the substrate.

[0021] In a further embodiment, in step S6, filter paper or cotton is placed at the powder discharge hole connected to the powder suction pipe and lightly pressed at the exhaust hole, and after waiting for one minute, it is checked whether there is any residual powder on the filter paper or cotton.

[0022] Compared with the prior art, the beneficial effects achieved by the present invention are: through the structural design of the powder discharge holes of thin-walled parts and the connection with the powder suction pipe and the powder blowing pipe, the powder cleaning sequence and the rotation angle of the turntable are reasonably designed, and for skin-reinforced parts with complex cavity structures, the powder remaining inside the cavity can be cleaned after the powder bed is melted, thereby avoiding the influence of residual powder agglomeration or agglomeration caused by subsequent heat treatment, thereby ensuring the part forming quality and improving the part performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of powder removal of thin-walled parts according to the present invention. DETAILED DESCRIPTION

[0024] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0025] See also Figure 1The present invention provides a technical solution: a powder cleaning method for thin-walled parts with cavity structures manufactured based on laser powder bed fusion additive manufacturing, comprising the following steps:

[0026] S1. Based on the laser powder bed fusion additive manufacturing technology, a thin-walled part with a cavity structure is manufactured by setting a support mechanism inside the cavity structure, and a fluid flow channel for connecting the inside of the cavity structure of the thin-walled part and the outside of the thin-walled part is set on the support mechanism;

[0027] S2. A plurality of powder discharge holes are provided on the thin-walled member, and a threaded structure for connecting with the outside is also provided in the powder discharge hole, and the fluid flow channel is connected with the outside of the thin-walled member through the powder discharge hole;

[0028] S3. Install a thin-walled part with a powder discharge hole on a base plate of a rotating table, the base plate is in a horizontal position, and a powder suction pipe and a plurality of powder blowing pipes are installed according to the positions of the powder discharge holes, so that the powder blowing device is connected to the thin-walled part through the powder blowing pipe, and the powder suction device is connected to the thin-walled part through the powder suction pipe. The total number of the powder suction pipes and the powder blowing pipes is equal to the number of the powder discharge holes. The powder suction pipe and the powder blowing pipe are both provided with threaded joints that match the threaded structure of the powder discharge holes. The thin-walled part is a part with the largest cross section as the symmetry plane, and the rotating axis of the rotating table and the largest cross section of the thin-walled part are in the same plane;

[0029] S4. Drive the rotating table to rotate around the rotating axis by a preset angle, turn on the powder blowing device and the powder suction device to clean the powder, turn off the powder blowing device and the powder suction device after the preset time is reached, drive the rotating table to rotate around the rotating axis in the opposite direction by twice the preset angle, then turn on the powder blowing device and the powder suction device to clean the powder, turn off the powder blowing device and the powder suction device after the preset time is reached, and reset the substrate to a horizontal state;

[0030] S5. Disconnect the powder suction pipe from the corresponding exhaust hole, disconnect one of the powder blowing pipes from the corresponding exhaust hole, connect the powder suction pipe to the exhaust hole corresponding to the powder blowing pipe, connect the powder blowing pipe to the powder exhaust hole corresponding to the powder suction pipe, and repeat step S4 until the last powder blowing pipe and the powder suction pipe are interchanged;

[0031] S6. Disconnect the powder suction pipe that has completed the last position exchange from the corresponding exhaust hole, and check whether there is residual powder at the powder exhaust hole connected to the powder suction pipe. If there is, continue to repeat steps S4 and S5 until the powder cleaning is completed.

[0032] In a further embodiment, in step S1, the support mechanism is a rib structure retained within the boundary track after Boolean operation between the honeycomb structure formed by the ribs and the boundary track formed at the maximum cross section of the cavity, the rib structure and the inner wall of the cavity form a plurality of closed chambers, and the fluid flow channel connects the plurality of closed chambers.

[0033] The cavity is flat, and the rib structure includes a main rib portion and a boundary rib portion. The main rib portion is a plurality of hexagonal structures surrounded by ribs, and the boundary rib portion is a plurality of open rib structures located within and adjacent to the boundary track. The hexagonal structure forms a closed first chamber with the inner wall of the cavity, and the open rib structure forms a closed second chamber with the inner wall of the cavity; the plurality of hexagonal structures and the plurality of open rib structures each have at least one connecting hole, and the connecting hole is used to connect two adjacent first chambers or two adjacent second chambers or adjacent first chambers and second chambers; a plurality of powder discharge holes are opened at positions along the boundary track on the thin-walled part, and the plurality of powder discharge holes are connected to the second chamber adjacent to the corresponding powder discharge holes;

[0034] A reinforcing oblique rib is also provided between two points located at the longest straight-line distance of the boundary track in the cavity, and the reinforcing oblique rib passes through the first cavity or the second cavity;

[0035] The boundary track is a polygonal structure, and adjacent powder discharge holes are arranged at positions corresponding to each side of the polygonal structure on the thin-walled part;

[0036] When the distance between the cavity and the maximum vertical cross-section is less than 3 mm, no powder discharge hole is provided on the thin-walled part at a position corresponding to one of the sides of the polygonal structure; when the distance between the cavity and the maximum vertical cross-section is greater than 3 mm, and when the length of one of the sides of the polygonal structure is greater than 50 mm, at least one powder discharge hole is provided on the thin-walled part at a position corresponding to one of the sides of the above-mentioned polygonal structure.

[0037] Through the above technical solution, by setting a supporting mechanism inside the cavity structure of the thin-walled part, the structure is optimized, which is beneficial to controlling the deformation of the thin-walled surface, is beneficial to the high-precision and effective forming of the thin-walled part, and facilitates the subsequent powder cleaning operation.

[0038] In a further embodiment, in step S3, the powder blowing device is a gas pressure storage tank, and the powder suction device is a vacuum cleaner.

[0039] Through the above technical solution, the gas pressure storage tank cooperates with the powder blowing pipe to carry out the powder blowing operation, and the vacuum cleaner cooperates with the powder suction pipe to carry out the powder suction operation.

[0040] In a further embodiment, in step S4, the preset angle is 30-60 degrees, and the preset time is 5-15 minutes.

[0041] The above technical solution makes it easier to clean the powder.

[0042] In a further embodiment, the preset angle is 45 degrees and the preset time is 10 minutes.

[0043] The above technical solution can improve the powder cleaning effect.

[0044] In a further embodiment, in step S1, the maximum distance of the cavity from the maximum cross section of the vertical thin-walled member is 50 mm, and the minimum distance of the cavity from the maximum cross section of the vertical thin-walled member is 3 mm.

[0045] Through the above technical solution, the size of the cavity is ensured, thereby ensuring the forming of the support mechanism, thereby ensuring the size of the thin-walled part, and facilitating the opening of the powder discharge hole.

[0046] In a further embodiment, in step S2, the number of the powder discharge holes is 4-6.

[0047] Through the above technical solution, by setting a smaller number of powder discharge holes, the powder blowing pipe and the powder suction pipe are interchanged to perform the powder cleaning operation without consuming a lot of time while ensuring the powder cleaning efficiency.

[0048] In a further embodiment, in step S3, the diameters of the powder suction pipe and the powder blowing pipe are 1-2 mm larger than the diameter of the powder discharge hole.

[0049] Through the above technical solution, the powder cleaning operation is facilitated by using the powder suction pipe and the powder blowing pipe which are larger than the diameter of the powder discharge hole.

[0050] In a further embodiment, in step S3, a channel for the powder suction pipe and the powder blowing pipe to pass through is opened on the substrate.

[0051] Through the above technical solution, the replacement and installation of the powder suction pipe and the powder blowing pipe are facilitated by the setting of the channel.

[0052] In a further embodiment, in step S6, filter paper or cotton is placed at the powder discharge hole connected to the powder suction pipe and lightly pressed at the exhaust hole, and after waiting for one minute, it is checked whether there is residual powder on the filter paper or cotton.

[0053] The above technical solution facilitates the detection of residual powder and ensures that the powder cleaning operation is sufficient.

[0054] Working principle: Based on the laser powder bed melting additive manufacturing technology, a thin-walled part with a cavity structure is manufactured by setting a supporting mechanism inside the cavity structure. The supporting mechanism is provided with a fluid flow channel for connecting the inside of the thin-walled part's cavity structure and the outside of the thin-walled part; a plurality of powder discharge holes are opened on the thin-walled part, and a threaded structure for connecting with the outside is also provided in the powder discharge hole, and the fluid flow channel is connected with the outside of the thin-walled part through the powder discharge hole; the thin-walled part with the powder discharge hole is installed on the substrate of the rotating table, and the substrate is in a horizontal position. A powder suction pipe and a plurality of powder blowing pipes are installed according to the position of the powder discharge hole, so that the gas pressure storage tank is connected with the thin-walled part through the powder blowing pipe, and the vacuum cleaner is connected with the thin-walled part through the powder suction pipe. The total number of powder suction pipes and powder blowing pipes is equal to the number of powder discharge holes. The powder suction pipe and the powder blowing pipe are both provided with threaded joints that cooperate with the threaded structure of the powder discharge hole. The thin-walled part is a part with the largest cross-section as the symmetry plane, and the rotating axis of the rotating table and the maximum cross-section of the thin-walled part are The surfaces are in the same plane; the rotating table is driven to rotate around the rotating axis by a preset angle, the gas pressure storage tank and the vacuum cleaner are turned on for powder cleaning, and the gas pressure storage tank and the vacuum cleaner are turned off after the preset time is reached, and the rotating table is driven to rotate around the rotating axis in the opposite direction by twice the preset angle, and the gas pressure storage tank and the vacuum cleaner are turned on for powder cleaning, and the gas pressure storage tank and the vacuum cleaner are turned off after the preset time is reached, and the substrate is reset to a horizontal state; the powder suction pipe is disconnected from the corresponding exhaust hole, one of the powder blowing pipes is disconnected from the corresponding exhaust hole, and the powder suction pipe is connected to the exhaust hole corresponding to the powder blowing pipe, and the powder blowing pipe is connected to the powder discharge hole corresponding to the powder suction pipe, and the above powder cleaning operation is repeated until the last powder blowing pipe and the powder suction pipe are interchanged; the powder suction pipe that has completed the position interchange last is disconnected from the corresponding exhaust hole, and whether there is residual powder at the powder discharge hole connected to the powder suction pipe is detected, and if there is, the powder cleaning operation is repeated until the powder cleaning is completed.

[0055] The preferred specific embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above specific embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical scheme of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing, characterized in that: The steps include: S1. Based on the laser powder bed fusion additive manufacturing technology, a thin-walled part having a cavity structure is manufactured by providing a support mechanism inside the cavity structure, wherein the support mechanism is provided with a fluid flow channel for connecting the inside of the cavity structure of the thin-walled part and the outside of the thin-walled part; S2. A plurality of powder discharge holes are provided on the thin-walled member, wherein the powder discharge hole is provided with a threaded structure for connecting with the outside, and the fluid flow channel is connected with the outside of the thin-walled member through the powder discharge hole; S3. The thin-walled part with the powder discharge hole is installed on the base plate of the rotating table, the base plate is in a horizontal position, and a powder suction pipe and a plurality of powder blowing pipes are installed according to the positions of the powder discharge holes, so that the powder blowing device is connected with the thin-walled part through the powder blowing pipe, and the powder suction device is connected with the thin-walled part through the powder suction pipe. The total number of the powder suction pipes and the powder blowing pipes is equal to the number of the powder discharge holes. The powder suction pipe and the powder blowing pipe are both provided with threaded joints that match the threaded structure of the powder discharge holes. The thin-walled part is a part with the largest cross section as the symmetry plane, and the rotating axis of the rotating table and the largest cross section of the thin-walled part are in the same plane; S4. Drive the rotating table to rotate around the rotating axis by a preset angle, turn on the powder blowing device and the powder sucking device to perform a powder cleaning operation, turn off the powder blowing device and the powder sucking device after the preset time is reached, drive the rotating table to rotate around the rotating axis in the opposite direction by twice the preset angle, then turn on the powder blowing device and the powder sucking device to perform a powder cleaning operation, turn off the powder blowing device and the powder sucking device after the preset time is reached, and reset the substrate to a horizontal state; S5. Disconnect the powder suction pipe from the corresponding exhaust hole, disconnect one of the powder blowing pipes from the corresponding exhaust hole, connect the powder suction pipe to the exhaust hole corresponding to the powder blowing pipe, connect the powder blowing pipe to the powder exhaust hole corresponding to the powder suction pipe, and repeat step S4 until the last powder blowing pipe and the powder suction pipe are interchanged; S6. Disconnect the powder suction pipe that has completed the last position exchange from the corresponding exhaust hole, and check whether there is residual powder at the powder exhaust hole connected to the powder suction pipe. If there is, continue to repeat steps S4 and S5 until the powder cleaning is completed.

2. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In step S1, the supporting mechanism is a rib structure retained within the boundary trajectory after Boolean operation between a honeycomb structure formed by ribs and a boundary trajectory formed at the maximum cross-section of the cavity, the rib structure and the inner wall of the cavity form a plurality of closed chambers, and the fluid flow channel connects the plurality of closed chambers.

3. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In the step S3, the powder blowing device is a gas pressure storage tank, and the powder suction device is a vacuum cleaner.

4. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In step S4, the preset angle is 30-60 degrees, and the preset time is 5-15 minutes.

5. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 4, characterized in that: The preset angle is 45 degrees, and the preset time is 10 minutes.

6. A powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In the step S1, the maximum distance of the cavity perpendicular to the maximum cross section of the thin-walled part is 50 mm, and the minimum distance of the cavity perpendicular to the maximum cross section of the thin-walled part is 3 mm.

7. The powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In the step S2, the number of the powder discharge holes is 4-6.

8. The powder cleaning method for manufacturing thin-walled parts with cavity structures by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In the step S3, the diameters of the powder suction pipe and the powder blowing pipe are 1-2 mm larger than the diameter of the powder discharge hole.

9. The powder cleaning method for thin-walled parts with cavity structures manufactured by laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In the step S3, a channel for the powder suction pipe and the powder blowing pipe to pass through is opened on the substrate.

10. The powder cleaning method for manufacturing thin-walled parts with cavity structures based on laser powder bed fusion additive manufacturing according to claim 1, characterized in that: In step S6, filter paper or cotton is placed at the powder discharge hole connected to the powder suction pipe and lightly pressed on the exhaust hole, and after waiting for one minute, it is checked whether there is residual powder on the filter paper or cotton.

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