Directional powder spreading device for selective laser melting forming

Abstract

The invention discloses a selective laser melting forming directional powder laying device which comprises a base plate at the bottom of a printing bin and a powder bin above the base plate. The first movement mechanisms are horizontally arranged on the side wall of the printing bin in the first direction, the second movement mechanism is horizontally arranged between the two first movement mechanisms in the second direction and horizontally moves in the first direction, and the first direction and the second direction are orthogonal. The powder spreading scraper is vertically mounted on the second movement mechanism and horizontally moves along a second direction under the action of the second movement mechanism; the size of a powder outlet of the powder bin is matched with the size of an upper end opening of the powder laying scraper. An annular rubber strip is arranged at the bottom of the powder laying scraper and used for scraping powder. The use amount of powder in the printing process can be reduced, and the workload of follow-up cleaning is reduced.

Description

Technical Field

[0001] The invention relates to the field of laser selective melting, and in particular to a laser selective melting molding directional powder spreading device. Background Art

[0002] Selective laser melting technology is a type of 3D printing technology. It is a revolutionary manufacturing technology developed in recent years. It is based on the basic principle of discrete-deposition. It selectively melts metal powder through high-energy lasers. Through layer-by-layer melting and accumulation, it can eventually form three-dimensional parts with tiny size and complex structure. It has the advantages of fast forming speed, high forming freedom, and single-piece small-batch production. Therefore, its application in aerospace, medical industry and other fields has developed rapidly.

[0003] However, when laying powder, traditional powder spreading mechanisms usually use a scraper that is longer than the length of the substrate to cover the entire surface of the substrate with powder. During the printing process, the laser selectively scans and melts the powder, and the powder in the space where the parts are not placed will not be used. Therefore, the traditional powder spreading method greatly increases the consumption of powder, especially expensive metal powders, such as precious metals and high-temperature alloys, which greatly increases the cost of printing. And when cleaning the powder after printing, the excess metal powder also increases the workload of cleaning. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a laser selective melting molding directional powder spreading device to reduce the demand and consumption of expensive metal powder and reduce the time cost of removing powder after printing.

[0005] The specific technical solutions are as follows:

[0006] A laser selective melting molding directional powder spreading device comprises: a powder bin, a first motion mechanism, a second motion mechanism, a powder spreading scraper, and a substrate; the substrate is horizontally arranged at the bottom of the printing bin, and the powder bin is arranged above the substrate and is used to contain powder for printing; first motion mechanisms are horizontally arranged along a first direction on two parallel side walls of the printing bin, and the second motion mechanism is horizontally arranged along a second direction between the two first motion mechanisms, and moves horizontally along the first direction under the action of the first motion mechanism, and the first direction and the second direction are two orthogonal directions on a horizontal plane;

[0007] The powder spreading scraper is vertically mounted on the second motion mechanism, and moves horizontally along the second direction under the action of the second motion mechanism; the powder outlet size of the powder bin is matched with the upper port size of the powder spreading scraper, and when the powder bin is docked with the powder spreading scraper, the powder falls from the powder bin into the powder spreading scraper; a ring-shaped rubber strip is provided at the bottom of the powder spreading scraper for flattening the powder.

[0008] Furthermore, the first motion mechanism includes: a shell body 1, a motor 1, a lead screw 1, and a connecting block 1; the shell body 1 is fixedly connected to the side wall of the printing chamber and its axis is parallel to the first direction; the motor 1 is fixedly connected to one axial end inside the shell body 1, one end of the lead screw 1 is coaxially fixed to the output shaft of the motor 1, and the other end of the lead screw 1 is rotatably connected to the other axial end of the shell body 1, so that the lead screw 1 can rotate around its axis under the action of the motor 1; a through hole is provided on the connecting block 1, and the through hole has an internal thread that is compatible with the lead screw 1, and the connecting block 1 is installed on the lead screw 1 through the through hole.

[0009] Furthermore, the shell is made of 6063 aluminum alloy profile.

[0010] Furthermore, the second motion mechanism comprises: a crossbeam, a second housing, a second motor, a second lead screw, and a second connecting block; both ends of the crossbeam are respectively mounted on the first motion mechanism, and moves horizontally along the first direction under the action of the first motion mechanism;

[0011] The second shell is fixedly connected to the crossbeam and its axis is parallel to the second direction. The second motor is fixedly connected to one axial end inside the second shell. One end of the second screw is coaxially fixed to the output shaft of the second motor, and the other end of the second screw is rotatably connected to the other axial end of the second shell, so that the second screw can rotate around its axis under the action of the second motor. A through hole is provided on the second connecting block, and the through hole has an internal thread matched with the second screw. The second connecting block is installed on the second screw through the through hole.

[0012] Furthermore, the cross beam and the second shell are both made of 6063 aluminum alloy profiles.

[0013] Furthermore, the powder silo is a shell structure with a hollow interior. The top powder inlet of the powder silo is used to load powder for printing, and the bottom powder outlet is used to output powder. A spring sliding cover is provided at the powder outlet. In the absence of any external force, the spring sliding cover is closed, that is, the powder outlet is closed; when the powder spreading scraper is docked with the powder outlet of the powder silo, the spring sliding cover opens.

[0014] Furthermore, the powder spreading scraper is a shell pipe with a hollow interior, which is narrow at the top and wide at the bottom. The shell pipe is divided into two sections, the upper section is a rectangular pipe; the lower section is a prism-shaped pipe with a rectangular bottom.

[0015] Furthermore, the powder bin, powder spreading scraper and base plate are all made of 316L stainless steel.

[0016] Furthermore, a gap of 1 mm is left between the bottom plane of the powder spreading scraper and the plane of the substrate, and a gap of 30 μm is left between the lower end of the annular rubber strip installed at the bottom and the substrate.

[0017] A method for directional powder spreading by laser selective melting molding is implemented according to the directional powder spreading device for laser selective melting molding, and comprises the following steps:

[0018] S1: Install the laser selective melting molding directional powder spreading device in the printing chamber as required, and load the powder for printing into the powder chamber;

[0019] S2: The control end sends a signal to drive the motor 1 and the motor 2 to rotate forward or reverse, so that the powder spreading scraper moves to the lower end of the powder bin to receive the powder;

[0020] S3: The control end drives the motor 1 and the motor 2 to rotate forward or reverse, so that the powder spreading scraper moves along a set path, and the powder falls onto the substrate through the channel in the powder spreading scraper and is flattened by the annular rubber strip;

[0021] S4: performing subsequent laser sintering steps;

[0022] S5: Repeat S2-S4 until printing is completed.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention uses a laser selective melting molding directional powder spreading device to avoid spreading powder on the entire substrate during metal printing and spreading powder, thereby reducing the amount of powder used in the printing process, reducing the mining and processing of new metal raw materials, reducing damage to the environment, and meeting the requirements of sustainable development; especially when printing precious metals, the cost of materials can be greatly reduced.

[0025] (2) After metal 3D printing is completed, the present invention needs to clean the parts buried by metal powder from the powder bed. Since the cleaning process needs to be cleaned through the glove window in a small isolation space, the process is usually cumbersome. Therefore, using less powder during the printing process can directly reduce the workload of subsequent cleaning and shorten the processing cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a laser selective melting molding directional powder spreading device in an embodiment of the present invention.

[0027] Figure 2 It is a cross-sectional view of the powder bin structure in an embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the structure of the longitudinal motion mechanism in an embodiment of the present invention.

[0029] Figure 4 Schematic diagram of the structure of the lateral motion mechanism in an embodiment of the present invention.

[0030] Figure 5It is a schematic diagram of the connection between the connecting block 2 and the scraper in an embodiment of the present invention.

[0031] Figure 6 It is a cross-sectional view of the scraper structure in an embodiment of the present invention.

[0032] Figure 7 2 is a bottom view schematic diagram of a scraper structure in an embodiment of the present invention.

[0033] In the figure, powder bin 1, first motion mechanism 2, shell 1 2-1, motor 1 2-2, screw 1 2-3, connecting block 1 2-4; second motion mechanism 3, shell 2 3-1, motor 2 3-2, screw 2 3-3, connecting block 2 3-4; powder scraper 4, annular rubber strip 4-1; substrate 5. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effect of the present invention will become more clear. The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] like Figure 1 As shown, a laser selective melting molding directional powder spreading device includes: a powder bin 1, a first motion mechanism 2, a second motion mechanism 3, a powder spreading scraper 4, and a substrate 5. The substrate 5 is horizontally arranged at the bottom of the printing bin, and the powder bin 1 is arranged directly above the substrate 5, with its powder drop opening facing vertically downward. Taking the vertical direction as the z direction, a pair of vertical and parallel walls of the printing bin are side walls, the normal of the side walls is the y direction, and the other pair of vertical and parallel walls are the front wall and the rear wall, the normal of the front and rear walls is the x direction, the x direction and the y direction are perpendicular to each other and are located on the same plane; the x direction is also the conventional movement direction of the scraper of the existing powder spreading device. The two side walls of the printing bin are respectively moved in the first direction (i.e. Figure 1 The first motion mechanism 2 is arranged horizontally along the x direction in the figure; the second motion mechanism 3 is arranged along the second direction (i.e. Figure 1 The second motion mechanism 3 is horizontally arranged between the two first motion mechanisms 2 (in the y direction); the two ends of the second motion mechanism 3 are respectively installed on the two first motion mechanisms 2, and can move horizontally along the first direction under the action of the first motion mechanism 2. The powder spreading scraper 4 is vertically installed on the second motion mechanism 3, and can move horizontally along the second direction under the action of the second motion mechanism 3. Preferably, the powder bin 1, the powder spreading scraper 4, and the base plate 5 are all made of 316L stainless steel.

[0036] like Figure 2As shown, the powder bin 1 is a shell structure with a hollow interior. The powder for printing can enter the powder bin 1 from the top powder inlet and fall out from the bottom powder outlet. A spring slide cover is provided at the powder outlet. When there is no external force, the spring slide cover is closed, and the powder cannot fall out through the powder outlet. The size of the powder outlet of the powder bin 1 is adapted to the size of the upper end of the powder spreading scraper 4. When the powder spreading scraper 4 moves to the bottom of the powder bin 1 and docks with the powder outlet, the spring slide cover is pushed, and the powder falling from the powder bin 1 can completely enter the powder spreading scraper 4 to receive the powder; when the powder spreading scraper 4 moves away, the spring slide cover is closed again under the action of the spring.

[0037] Preferably, the lower end of the powder bin 1 is arranged to be a structure bent in the first direction. On the one hand, this design ensures that when the powder bin 1 is set close to the front wall or the rear wall of the printing bin, the powder scraper 4 will not collide with the front wall or the rear wall. On the other hand, the curved structure slows down the speed at which the powder falls, which can better achieve the acceptance of the powder.

[0038] like Figure 3 As shown, the first motion mechanism 2 includes: a housing 2-1, a motor 2-2, a lead screw 2-3, and a connecting block 2-4. The housing 2-1 is a profile made of 6063 aluminum alloy, fixedly connected to the side wall of the printing chamber and with its axis parallel to the x direction; the motor lead screw structure composed of a motor 2-2 and a lead screw 2-3 is arranged inside the housing 2-1, and the housing 2-1 plays a protective role. In the motor lead screw structure, the motor 2-2 is fixedly connected to one axial end of the housing 2-1, one end of the lead screw 2-3 is coaxially fixedly connected to the output shaft of the motor 2-2, and the other end of the lead screw 2-3 is rotatably connected to the other axial end of the housing 2-1, so that the lead screw 2-3 can rotate around its axis under the action of the motor 2-2. The connecting block 2-4 includes a connecting platform and a protruding structure thereon, a through hole is provided on the protruding structure, and the through hole has an internal thread matched with the lead screw 2-3. The connecting block 2-4 is installed on the lead screw 2-3 through the through hole. When the lead screw 2-3 rotates, the connecting block 2-4 can move horizontally along the x direction. At this time, the lead screw 2-3 acts as a guide rail.

[0039] like Figure 4As shown, the second motion mechanism 3 includes: a crossbeam, a shell 3-1, a motor 3-2, a lead screw 3-3, and a connection block 3-4. The two ends of the crossbeam are respectively fixedly connected to the connection platform of the connection block 2-4, and the crossbeam and the shell 3-1 are also made of 6063 aluminum alloy profiles; the shell 3-1 is fixedly connected to the crossbeam, and the motor lead screw structure is arranged inside it, and the shell 3-1 plays a protective role. In the motor lead screw structure, the motor 3-2 is fixedly connected to one axial end of the shell 3-1, one end of the lead screw 3-3 is coaxially fixedly connected to the output shaft of the motor 3-2, and the other end of the lead screw 3-3 is rotatably connected to the other axial end of the shell 3-1, so that the lead screw 3-3 can rotate around its axis under the action of the motor 3-2. A through hole is provided on the connecting block 3-4, and an internal thread matching the lead screw 3-3 is provided in the through hole. The connecting block 3-4 is installed on the lead screw 3-3 through the through hole. When the lead screw 3-3 rotates, the connecting block 3-4 can move horizontally along the y direction.

[0040] The longitudinal motion mechanism 2 cooperates with the transverse motion mechanism 3. Through the forward and reverse rotation of motor 1 2-2 and motor 2 3-2, the corresponding connecting block moves on the corresponding screw rod, thereby driving the powder scraper 4 to realize customized movement in the x direction and y direction.

[0041] like Figure 5 As shown, the powder spreading scraper 4 is fixedly connected to the connecting block 2 3-4. Figure 6 As shown, the powder spreading scraper 4 is a shell pipe, which is divided into two sections. The upper section is a rectangular pipe; the lower section is a prism-shaped pipe with a rectangular bottom; the powder spreading scraper 4 is narrow at the top and wide at the bottom. Figure 7 As shown, a "mouth"-shaped groove is provided at the bottom of the powder spreading scraper 4, and a ring-shaped rubber strip 4-1 is installed in the groove for flattening the powder. In this embodiment, there is a 1mm gap between the bottom plane of the powder spreading scraper 4 and the plane of the substrate 5. After the ring-shaped rubber strip 4-1 is installed, there is a 30μm gap between the lower end of the ring-shaped rubber strip 4-1 and the substrate 5. During the powder spreading process, the powder spreading scraper 4 can flatten the powder when spreading the powder in the x-direction and the y-direction, and lay a metal powder layer with a thickness of 30μm.

[0042] According to the above-mentioned laser selective melting forming directional powder spreading device, this embodiment also proposes a laser selective melting forming directional powder spreading method, which specifically includes the following steps:

[0043] S1: Install the laser selective melting molding directional powder spreading device in the printing chamber as required, and load the powder for printing into the powder chamber 1.

[0044] S2: The control end sends a signal to drive the motor 1 2-2 and the motor 2 3-2 to rotate forward or reverse, so that the powder spreading scraper 4 moves to the lower end of the powder bin 1 to receive the powder.

[0045] S3: The control end drives motor 1 2-2 and motor 2 3-2 to rotate forward or reverse, so that the powder spreading scraper 4 moves along the set path, and the powder falls onto the substrate 5 through the channel in the powder spreading scraper 4 and is flattened by the annular rubber strip.

[0046] S4: Perform the subsequent laser sintering step.

[0047] S5: Repeat S2-S4 until printing is completed.

[0048] Those skilled in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the invention shall be included in the protection scope of the invention.

Claims

1. A laser selective melting molding directional powder spreading device, characterized in that: include: Powder bin, first motion mechanism, second motion mechanism, powder spreading scraper, substrate; The substrate is horizontally arranged at the bottom of the printing chamber, and the powder chamber is arranged above the substrate and is used to contain powder for printing; first motion mechanisms are horizontally arranged along a first direction on two parallel side walls of the printing chamber, and the second motion mechanism is horizontally arranged along a second direction between the two first motion mechanisms, and moves horizontally along the first direction under the action of the first motion mechanism, and the first direction and the second direction are two orthogonal directions on a horizontal plane; The powder spreading scraper is vertically mounted on the second motion mechanism, and moves horizontally along the second direction under the action of the second motion mechanism; the powder outlet size of the powder bin is matched with the upper port size of the powder spreading scraper, and when the powder bin is docked with the powder spreading scraper, the powder falls from the powder bin into the powder spreading scraper; a ring-shaped rubber strip is provided at the bottom of the powder spreading scraper for flattening the powder.

2. The laser selective melting forming directional powder spreading device according to claim 1, characterized in that: The first motion mechanism includes: a shell body 1, a motor 1, a lead screw 1, and a connecting block 1; the shell body 1 is fixedly connected to the side wall of the printing chamber and its axis is parallel to the first direction; the motor 1 is fixedly connected to one axial end inside the shell body 1, one end of the lead screw 1 is coaxially fixedly connected to the output shaft of the motor 1, and the other end of the lead screw 1 is rotatably connected to the other axial end of the shell body 1, so that the lead screw 1 can rotate around its axis under the action of the motor 1; a through hole is provided on the connecting block 1, and the through hole has an internal thread matched with the lead screw 1, and the connecting block 1 is installed on the lead screw 1 through the through hole.

3. The laser selective melting molding directional powder spreading device according to claim 2 is characterized in that: The shell body is made of 6063 aluminum alloy profile.

4. The laser selective melting forming directional powder spreading device according to claim 1, characterized in that: The second motion mechanism comprises: a crossbeam, a second housing, a second motor, a second lead screw, and a second connecting block; both ends of the crossbeam are respectively mounted on the first motion mechanism, and the crossbeam performs horizontal motion along the first direction under the action of the first motion mechanism; The second shell is fixedly connected to the crossbeam and its axis is parallel to the second direction. The second motor is fixedly connected to one axial end inside the second shell. One end of the second screw is coaxially fixed to the output shaft of the second motor, and the other end of the second screw is rotatably connected to the other axial end of the second shell, so that the second screw can rotate around its axis under the action of the second motor. A through hole is provided on the second connecting block, and the through hole has an internal thread matched with the second screw. The second connecting block is installed on the second screw through the through hole.

5. The laser selective melting molding directional powder spreading device according to claim 4 is characterized in that: The cross beam and the second shell are both made of 6063 aluminum alloy profiles.

6. The laser selective melting molding directional powder spreading device according to claim 1, characterized in that: The powder bin is a shell structure with a hollow interior. The top powder inlet of the powder bin is used to load powder for printing, and the bottom powder outlet is used to output powder. A spring slide cover is provided at the powder outlet. In the absence of any external force, the spring slide cover is closed, that is, the powder outlet is closed; when the powder spreading scraper is docked with the powder outlet of the powder bin, the spring slide cover opens.

7. The laser selective melting molding directional powder spreading device according to claim 1, characterized in that: The powder spreading scraper is a shell pipe with a hollow interior, which is narrow at the top and wide at the bottom. The shell pipe is divided into two sections, the upper section is a rectangular pipe; the lower section is a prism-shaped pipe with a rectangular bottom.

8. The laser selective melting molding directional powder spreading device according to claim 1, characterized in that: The powder bin, powder spreading scraper and base plate are all made of 316L stainless steel.

9. The laser selective melting forming directional powder spreading device according to claim 1, characterized in that: A gap of 1 mm is left between the bottom plane of the powder spreading scraper and the plane of the substrate, and a gap of 30 μm is left between the lower end of the annular rubber strip installed at the bottom and the substrate.

10. A method for directional powder spreading by laser selective melting molding, implemented by the directional powder spreading device for laser selective melting molding according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Install the laser selective melting molding directional powder spreading device in the printing chamber as required, and load the powder for printing into the powder chamber; S2: The control end sends a signal to drive the motor 1 and the motor 2 to rotate forward or reverse, so that the powder spreading scraper moves to the lower end of the powder bin to receive the powder; S3: The control end drives the motor 1 and the motor 2 to rotate forward or reverse, so that the powder spreading scraper moves along a set path, and the powder falls onto the substrate through the channel in the powder spreading scraper and is flattened by the annular rubber strip; S4: performing subsequent laser sintering steps; S5: Repeat S2-S4 until printing is completed.

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