An additive manufacturing apparatus based on the principle of fluidized bed and method thereof

Abstract

An additive manufacturing equipment based on the principle of fluidized bed and a method thereof, wherein the equipment comprises a forming cylinder and a base plate, the base plate comprises an upper base plate and a lower base plate, and a gas-permeable porous material is arranged between the upper base plate and the lower base plate, the upper base plate is provided with a plurality of air holes, and the lower base plate is provided with at least one gas inlet for introducing external gas, the additive manufacturing equipment takes metal powder as raw material, when a continuous printing work package forms an intermediate part of a preset height, the base plate is lowered by N layer thicknesses, and a filling material is added to a working area of the forming cylinder, the external gas is controlled to be discharged into the gas-permeable porous material through the gas inlet, and then discharged into the metal powder on the base plate through the gas-permeable porous material and the plurality of air holes, so that the metal powder flows and the filling material sinks into the base plate. The metal powder and the filling material are replaced based on the base plate, the printing of the entire work package can be continuously completed even if the metal powder is not enough to fill the entire forming cylinder, the utilization rate of the metal powder is improved, and the printing cost is reduced.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing technology, and in particular to an additive manufacturing device and method based on the fluidized bed principle. Background Technology

[0002] Laser powder bed fusion (LPF) is a high-precision metal additive manufacturing technology. The basic process is as follows: a powder feeding device delivers a certain amount of powder to the worktable, and a powder spreading device spreads the powder evenly onto the substrate in the forming cavity or the top surface of the printed part. The laser performs selective sintering based on the layered content defined by the CAD model. After the current layer is sintered, the substrate descends by one layer thickness, and the powder feeding device supplies powder again in the same manner. The sintering process repeats with the number of layers as the number of cycles, and after several layers are scanned and sintered, the entire part is formed.

[0003] Due to limitations in powder feeding and recycling methods, current metal additive manufacturing technology only recovers excess powder after the initial powder layer is laid out; residual powder within the forming cavity cannot be recovered, resulting in low real-time powder utilization. Therefore, to continuously print large metal parts, the amount of powder required is far greater than that needed to print just the workpiece. This significantly increases the printing cost of large metal parts, hindering the widespread adoption and application of additive manufacturing for high-cost metals. Summary of the Invention

[0004] To address the aforementioned technical problems in the existing technology, this invention provides an additive manufacturing device and method based on the fluidized bed principle. This additive manufacturing device replaces metal powder and filler material on a substrate, enabling continuous printing of the entire work package even if the metal powder is insufficient to fill the entire molding cylinder, thereby improving powder utilization and reducing printing costs.

[0005] To achieve the above objectives, the present invention provides an additive manufacturing apparatus based on the fluidized bed principle, comprising a forming cylinder and a substrate. The substrate includes an upper substrate, a lower substrate, and a permeable porous material disposed between the upper and lower substrates. The upper substrate has a plurality of air holes, and the lower substrate has at least one air inlet for introducing external gas.

[0006] The additive manufacturing equipment uses metal powder as raw material. When the work package is continuously printed to form an intermediate part of a preset height, the substrate is lowered by N layers and filler material is added to the working area of ​​the forming cylinder. The filler material has a three-dimensional structure, the density of the filler material is greater than the density of the metal powder, the minimum cross-section of the filler material is greater than a and greater than the inner diameter of the pores, N*a is greater than the minimum cross-section of the filler material, N≧1 and N≦ the total number of layers of the work package, and a is the layer thickness of the work package.

[0007] External gas is controlled to be discharged into the permeable porous material through the air inlet, and then discharged into the metal powder on the substrate through the permeable porous material and several air holes, so that the metal powder flows and the filling material sinks into the substrate, and the metal powder is replaced on top of the filling material.

[0008] As a further preferred embodiment of the present invention, the additive manufacturing equipment further includes a sealing ring disposed around the perimeter between the upper substrate and the lower substrate.

[0009] As a further preferred embodiment of the present invention, the breathable porous material is wood pulp sponge, polyurethane sponge, activated carbon non-adhesive cotton, porous foam metal, porous zirconia ceramic, or ceramic alumina.

[0010] As a further preferred embodiment of the present invention, the shape of the filling material is a sphere, cuboid, cube, or tetrahedron.

[0011] As a further preferred embodiment of the present invention, when the shape of the filling material is sphere, the diameter of the filling material is greater than or equal to 10 times the particle size of the metal powder.

[0012] As a further preferred embodiment of the present invention, when the filling material is copper balls or tungsten balls, the diameter of the copper balls or tungsten balls is 0.2 mm to 100 mm.

[0013] The present invention also provides a method for additive manufacturing equipment based on the fluidized bed principle, the method being based on the additive manufacturing equipment based on the fluidized bed principle described in any of the preceding claims, wherein the method includes the following steps:

[0014] Step S1: Using metal powder as raw material, continuously print work packages using additive manufacturing. When the continuously printed work package forms an intermediate part of a preset height, the substrate is lowered by N layers, and filler material is added to the working area.

[0015] Step S2: Control the external gas to be discharged into the breathable porous material through the air inlet, and discharge the metal powder on the substrate through the breathable porous material and several air holes, so that the metal powder flows and the filling material sinks into the substrate, and the metal powder is replaced above the filling material.

[0016] Step S3: Control the substrate to rise by N-1 layers, spread metal powder on the working area using a scraper, and return to step S1 until the work package printing is completed and the process ends.

[0017] As a further preferred embodiment of the present invention, the continuous printing of the work package using additive manufacturing specifically includes the following steps:

[0018] Step S11: Spread the metal powder evenly onto the working area of ​​the current layer and selectively scan the working area;

[0019] Step S12: After the current layer's working area is scanned, control the substrate to descend by one layer thickness and return to step S11.

[0020] As a further preferred embodiment of the present invention, the preset height is greater than the minimum cross-section of the filling material.

[0021] As a further preferred embodiment of the present invention, the preset height is 2-3 times the minimum cross-section of the filling material.

[0022] The additive manufacturing equipment and method based on the fluidized bed principle of the present invention, by adopting the above technical solution, has the following advantages:

[0023] Beneficial effects:

[0024] This invention uses a fluidized bed principle substrate to replace metal powder and filler material, enabling continuous printing of the entire work package even when the metal powder is insufficient to fill the entire molding cylinder, thereby improving the utilization rate of metal powder; and since the price of metal powder is generally much higher than that of filler material, the printing cost is greatly reduced. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the substrate structure in the additive manufacturing equipment based on the fluidized bed principle of this invention;

[0026] Figure 2 for Figure 1 Cross-sectional view;

[0027] Figure 3 A working state diagram a is provided for an embodiment of the additive manufacturing equipment based on the fluidized bed principle of the present invention;

[0028] Figure 4 Figure b shows the working state of an embodiment of the additive manufacturing equipment based on the fluidized bed principle of the present invention.

[0029] Figure 5 Diagram c shows the working state of an embodiment of the additive manufacturing equipment based on the fluidized bed principle of the present invention.

[0030] Figure 6 A working state diagram d is provided for an embodiment of the additive manufacturing equipment based on the fluidized bed principle of the present invention;

[0031] Figure 7 This is a flowchart illustrating an embodiment of the additive manufacturing method based on the fluidized bed principle of the present invention.

[0032] Marked in the image:

[0033] 1. Metal powder, 2. Intermediate component, 3. Molding cylinder, 4. Substrate, 5. Copper ball, 6. Scraper, 4.1. Upper substrate, 4.2. Pores, 4.3. Breathable porous material, 4.4. Sealing ring, 4.5. Lower substrate, 4.6. Air inlet. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0035] To address the technical problems of existing metal additive manufacturing technologies, such as the need for a significantly larger amount of powder than required to produce a workpiece, low real-time powder utilization, and increased printing costs, this invention provides an additive manufacturing device based on the fluidized bed principle, such as... Figure 1 and Figure 2 As shown, the additive manufacturing equipment includes a forming cylinder 3 and a substrate 4. The substrate 4 includes an upper substrate 4.1, a lower substrate 4.5, and a breathable porous material 4.3 disposed between the upper substrate 4.1 and the lower substrate 4.5. The upper substrate 4.1 is provided with a plurality of air holes 4.2, and the lower substrate 4.5 is provided with at least one air inlet 4.6 for introducing external gas.

[0036] The additive manufacturing equipment uses metal powder 1 as raw material. When the work package is continuously printed to form an intermediate part 2 of a preset height, the substrate 4 drops by N layers and adds filler material to the working area of ​​the forming cylinder 3. The filler material has a three-dimensional structure and its density is greater than that of the metal powder 1. The minimum cross-section of the filler material is greater than a and greater than the inner diameter of the pore 4.2. N*a is greater than the minimum cross-section of the filler material. N≧1 and N≦ the total number of layers of the work package. a is the layer thickness of the work package.

[0037] External gas is controlled to be discharged into the breathable porous material 4.3 through the air inlet 4.6, and then discharged into the metal powder 1 on the substrate 4 through the breathable porous material 4.3 and several air holes 4.2, so that the metal powder 1 flows and the filling material sinks into the substrate 4, and the metal powder 1 is replaced above the filling material.

[0038] Preferably, in order to ensure the airtightness between the upper substrate 4.1 and the lower substrate 4.5, all the gas is discharged into the metal powder 1 through the vent 4.2. The additive manufacturing equipment also includes a sealing ring 4.4, which is disposed around the upper substrate 4.1 and the lower substrate 4.5.

[0039] In one specific implementation, the breathable porous material 4.3 is wood pulp sponge, polyurethane sponge, activated carbon non-adhesive cotton, porous foam metal, porous zirconia ceramic, or ceramic alumina. The shape of the filling material is sphere, cuboid, cube, or tetrahedron, and of course, other three-dimensional structures are also possible, which will not be listed here.

[0040] When the filler material is spherical, preferably, the diameter of the filler material is greater than or equal to 10 times the particle size of the metal powder 1, which can further facilitate the subsequent separation of the filler material and the metal powder 1.

[0041] In another specific embodiment, when the filling material is copper ball 5 or tungsten ball, the diameter of the copper ball 5 or tungsten ball is 0.2mm~100mm. The diameter of the pore 4.2 is 0.1~3mm and the pore spacing is 1~50mm; it should be noted that the gas introduced through the air inlet 4.6 is argon, nitrogen or helium.

[0042] It should be noted that since the core of protection of this invention lies in the substrate 4 with a fluidized bed, the existing components included in the additive manufacturing equipment will not be specifically described here. For example, the additive manufacturing equipment also includes existing powder spreading devices, energy radiation sources, scanning systems, etc.

[0043] Further reading Figure 7 The present invention also provides a method for additive manufacturing equipment based on the fluidized bed principle, the method being based on the additive manufacturing equipment based on the fluidized bed principle described in any of the above embodiments, wherein the method includes the following steps:

[0044] Step 1: Using metal powder 1 as raw material, continuously print work packages using additive manufacturing, such as... Figure 3 As shown; when the continuous printing of the work package forms the intermediate part 2 of the preset height, the substrate 4 descends by N layers and adds filler material to the working area, such as Figure 4 As shown;

[0045] Step 2: Control the external gas to be discharged into the breathable porous material 4.3 through the air inlet 4.6, and then into the metal powder 1 on the substrate 4 through the breathable porous material 4.3 and several air holes 4.2, so that the metal powder 1 flows and the filling material sinks into the substrate 4, and the metal powder 1 is replaced above the filling material; such as Figure 5 As shown.

[0046] Step 3: Control the substrate 4 to rise by N-1 layers, and spread metal powder 1 on the working area using a scraper 6, such as... Figure 6 As shown. Return to step 1 and continue until the work package is printed and the process ends.

[0047] In specific implementation, the continuous printing of work packages using additive manufacturing includes the following steps:

[0048] Step 11: Spread the metal powder 1 evenly onto the working area of ​​the current layer and perform selective scanning on the working area;

[0049] Step 12: After the current layer's working area is scanned, control the substrate 4 to descend by one layer thickness and return to step 11 until the continuous printing of work packages forms the intermediate part 2 of the preset height, thus ending the current process.

[0050] The preset height is greater than the minimum cross-section of the filler material. Preferably, the preset height is 2-3 times the minimum cross-section of the filler material, so that more metal powder 1 in the forming cylinder 3 can be replaced while taking printing efficiency into account, thus further improving the utilization rate of the powder. More preferably, the preset height is equal to N layer thicknesses, that is, when the continuous printing of the work package forms an intermediate part 2 with an N layer thickness, the substrate 4 drops by N layer thicknesses.

[0051] It should be noted that this application is more suitable for printing large, thin-walled parts, meaning that it can better improve powder utilization for such parts.

[0052] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below in the form of embodiments.

[0053] Example 1: Printing of Large Thin-Walled Parts

[0054] The additive manufacturing equipment includes a forming cylinder 3 and a substrate 4. The substrate 4 includes an upper substrate 4.1 (made of carbon steel), vents 4.2 with a diameter of 1 mm and a hole spacing of 10 mm, low-density polyurethane foam, a sealing ring 4.4, a lower substrate 4.5, and an air inlet 4.6, such as... Figure 1 and 2 As shown. 316L stainless steel powder and a thin-walled part being printed are deposited on substrate 4, such as... Figure 3 As shown.

[0055] Figure 4In the process, when the part is printed to a height of 50mm (100 layers, each layer thickness is 0.05mm), the substrate 4 descends 50mm along with the part. Copper balls 5 with a diameter of 3mm are added. Nitrogen gas is introduced through the air inlet 4.6 and diffuses into the breathable polyurethane foam material, through which 316L powder is discharged via pores 4.2. At this time, due to the influence of nitrogen, the 316L powder has increased fluidity. The 3mm copper balls 5 sink above the substrate 4, and the 316L powder height increases, being replaced by the higher-density copper balls 5. Figure 5 As shown.

[0056] Figure 6 In the process, the substrate 4 rises to a height of 50mm-0.05mm (0.05mm is the thickness of one layer in the work package), and 316L stainless steel powder is laid. The scraper 6 moves 3 times to achieve the leveling of the powder surface. Excess powder can be recycled by sieving.

[0057] Repeat the above steps to continue printing layer by layer until the entire work package is printed. During this process, using the apparatus and method of this application, the amount of powder prepared can be reduced by three times. After printing, the copper balls 5 and 316L stainless steel powder can be sieved through a screen for reuse.

[0058] Example 2: Printing with silver powder

[0059] The additive manufacturing equipment includes a forming cylinder 3 and a substrate 4. The substrate 4 includes an upper substrate 4.1 (made of silver), pores 4.2 with a diameter of 1.5 mm and a hole spacing of 8 mm, low-density porous zirconia ceramic, a sealing ring 4.4, a lower substrate 4.5, and an air inlet 4.6, such as... Figure 1 and 2 As shown. Silver powder and silver parts being printed are deposited on substrate 4, as... Figure 3 As shown.

[0060] Figure 4 In the process, when the part is printed to a height of 20mm (100 layers, each layer is 0.02mm thick), the substrate 4 is lowered by 20mm. After adding tungsten balls with a diameter of 1mm, argon gas is introduced through the air inlet 4.6. The diffused gas diffuses into the permeable, low-density porous zirconia ceramic, and silver powder is discharged through the pores 4.2. At this time, due to the influence of argon gas, the fluidity of the silver powder is enhanced, and the 1mm tungsten balls sink above the substrate 4, increasing the height of the silver powder. Figure 5 As shown.

[0061] Figure 6 In the process, the substrate 4 rises 20mm to 0.02mm (0.02mm is the thickness of one layer in the work package), silver powder is laid, and the scraper 6 moves once to level the powder surface. Excess powder is recycled for later use.

[0062] Repeat the above steps to continue printing layer by layer until the entire work package is printed. During this process, using the apparatus and method of this application, the amount of powder prepared can be reduced by four times. After printing, the tungsten balls and silver powder can be sieved through a screen for reuse.

[0063] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An additive manufacturing device based on the fluidized bed principle, characterized in that, The system includes a molding cylinder and a substrate. The substrate comprises an upper substrate, a lower substrate, and a breathable porous material disposed between the upper and lower substrates. The upper substrate has a plurality of air holes, and the lower substrate has at least one air inlet for introducing external gas. The additive manufacturing equipment uses metal powder as raw material. When the work package is continuously printed to form an intermediate part of a preset height, the substrate is lowered by N layers and filler material is added to the working area of ​​the forming cylinder. The filler material has a three-dimensional structure, the density of the filler material is greater than the density of the metal powder, the minimum cross-section of the filler material is greater than a and greater than the inner diameter of the pores, N*a is greater than the minimum cross-section of the filler material, N≧1 and N≦ the total number of layers of the work package, and a is the layer thickness of the work package. External gas is controlled to be discharged into the permeable porous material through the air inlet, and then discharged into the metal powder on the substrate through the permeable porous material and several air holes, so that the metal powder flows and the filling material sinks into the substrate, and the metal powder is replaced on top of the filling material.

2. The additive manufacturing equipment based on the fluidized bed principle according to claim 1, characterized in that, The additive manufacturing equipment also includes a sealing ring disposed around the perimeter between the upper substrate and the lower substrate.

3. The additive manufacturing equipment based on the fluidized bed principle according to claim 1, characterized in that, The breathable porous material is wood pulp sponge, polyurethane sponge, activated carbon non-adhesive cotton, porous foam metal, porous zirconia ceramic, or ceramic alumina.

4. The additive manufacturing equipment based on the fluidized bed principle according to claim 1, characterized in that, The filling material is in the shape of a sphere, cuboid, cube, or tetrahedron.

5. The additive manufacturing equipment based on the fluidized bed principle according to claim 4, characterized in that, When the filler material is spherical, the diameter of the filler material is greater than or equal to 10 times the particle size of the metal powder.

6. The additive manufacturing equipment based on the fluidized bed principle according to claim 5, characterized in that, When the filler material is copper or tungsten balls, the diameter of the copper or tungsten balls is 0.2 mm to 100 mm.

7. The method of the additive manufacturing equipment based on the fluidized bed principle according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Using metal powder as raw material, continuously print work packages using additive manufacturing. When the continuously printed work package forms an intermediate part of a preset height, the substrate is lowered by N layers, and filler material is added to the working area. Step S2: Control the external gas to be discharged into the breathable porous material through the air inlet, and discharge the metal powder on the substrate through the breathable porous material and several air holes, so that the metal powder flows and the filling material sinks into the substrate, and the metal powder is replaced above the filling material. Step S3: Control the substrate to rise by N-1 layers, spread metal powder on the working area using a scraper, and return to step S1 until the work package printing is completed and the process ends.

8. The method of additive manufacturing equipment based on fluidized bed principle according to claim 7, characterized in that, The continuous printing of work packages using additive manufacturing specifically includes the following steps: Step S11: Spread the metal powder evenly onto the working area of ​​the current layer and selectively scan the working area; Step S12: After the current layer's working area is scanned, control the substrate to descend by one layer thickness and return to execute step S11.

9. The method of additive manufacturing equipment based on fluidized bed principle according to claim 7 or 8, characterized in that, The preset height is greater than the minimum cross-section of the filling material.

10. The method of the additive manufacturing equipment based on the fluidized bed principle according to claim 9, characterized in that, The preset height is 2-3 times the minimum cross-section of the filling material.

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