Additive manufacturing system and method for metal powder

Abstract

The invention discloses an additive manufacturing system and method for metal powder, belongs to the technical field of additive manufacturing, and aims to solve the problem that the forming precision of a final product is affected due to non-uniform density of a green body caused by insufficient densification in a green body manufacturing and forming process in the prior art. The system comprises a forming cylinder, a powder laying mechanism, a binder spraying mechanism and a compacting mechanism. The powder laying mechanism is used for laying powder in the forming cylinder to form a single layer; the binder spraying mechanism is used for spraying a binder into the single layer; and the compacting mechanism is used for compacting the single layer sprayed with the binder. According to the method, the single layer sprayed with the binder is compacted after the binder is sprayed into the single layer. The method can be used for additive manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to an additive manufacturing system and method for metal powder. Background Art

[0002] Metal powder combined with binder jetting additive manufacturing is an additive manufacturing technology that uses a binder and metal powder to create three-dimensional objects.

[0003] The specific additive manufacturing process is as follows:

[0004] Spread a layer of metal powder and spray a binder into the metal powder; repeat the above steps until the green body manufacturing of the three-dimensional workpiece is completed; and sinter the green body.

[0005] However, during the green body manufacturing process, insufficient densification results in uneven density of the green body. In the subsequent sintering process, due to the low density of the green body, large deformation will occur, and the powder gap is large, resulting in a long sintering time, which affects the molding accuracy and performance of the final product. Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide an additive manufacturing system and method for metal powders, so as to solve the problem in the prior art that insufficient densification during the green body manufacturing process leads to uneven density of the green body, affecting the molding accuracy and performance of the final product.

[0007] The purpose of the present invention is mainly achieved through the following technical solutions.

[0008] The present invention provides an additive manufacturing system for metal powder, comprising a forming cylinder, a powder spreading mechanism, a binder injection mechanism and a compacting mechanism; the powder spreading mechanism is used to spread powder in the forming cylinder to form a single layer; the binder injection mechanism is used to inject binder into the single layer; the compacting mechanism is used to compact the single layer injected with binder.

[0009] Furthermore, the additive manufacturing system also includes a first vertical drive mechanism, a first horizontal drive structure, a second horizontal drive mechanism and a second vertical drive mechanism; the first vertical drive mechanism is used to drive the forming cylinder to reciprocate in the vertical direction; the first horizontal drive mechanism is used to drive the powder spreading mechanism to reciprocate horizontally, so that the powder spreading mechanism leaves or is directly above the forming cylinder; the second horizontal drive mechanism is used to drive the binder injection mechanism to reciprocate horizontally, so that the binder injection mechanism leaves or is directly above the forming cylinder; the second vertical drive mechanism is used to drive the compaction mechanism to reciprocate in the vertical direction, so that the compaction mechanism is close to or away from the single layer.

[0010] Furthermore, the additive manufacturing system also includes a powder supply mechanism, and a powder outlet of the powder supply mechanism is connected to a powder inlet of the powder spreading mechanism.

[0011] Furthermore, the powder supply mechanism is fixedly connected to the powder spraying mechanism.

[0012] Furthermore, the additive manufacturing system also includes a workbench and a bracket. The workbench is arranged on the mounting surface through the bracket. A mounting groove for accommodating the forming cylinder is provided on the workbench, and the forming cylinder is located in the mounting groove.

[0013] Furthermore, the additive manufacturing system also includes a slide rail, and the powder spreading mechanism and the binder injection mechanism are arranged on the slide rail and are slidably connected to the slide rail.

[0014] The present invention also provides an additive manufacturing method for metal powder, which adopts the additive manufacturing system for metal powder.

[0015] Furthermore, the additive manufacturing method comprises the following steps:

[0016] Step 1: The powder spreading mechanism is turned on and moves from the first side of the forming cylinder to the second side. During the movement, powder is spread into the forming cylinder to form a single layer.

[0017] Step 2: The powder spreading mechanism is reset and closed, and the binder spraying mechanism is turned on. The binder spraying mechanism moves from the second side of the forming cylinder to the first side, and during the movement, the binder is sprayed into the single layer;

[0018] Step 3: The binder spraying mechanism is reset and closed, and the compacting mechanism is turned on to compact the single layer sprayed with the binder;

[0019] Step 4: The compacting mechanism is reset and closed, and the forming cylinder moves downward;

[0020] Step 5: Repeat steps 1 to 4 until additive manufacturing is completed.

[0021] Furthermore, in step 1, the initial thickness of the single layer is 0.1 to 500 μm.

[0022] Furthermore, the following steps are also included between step 4 and step 5:

[0023] The compacted single layer is pre-cured.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] A) The additive manufacturing system for metal powder provided by the present invention is provided with a compacting mechanism specifically used for compacting a single layer sprayed with a binder. Through the setting of the compacting mechanism, each time after the binder is sprayed in the single layer, the current single layer can be compacted to reduce the gaps in the single layer, compress the thickness of the single layer, and improve the compactness of the single layer and the green body, so that the workpiece approaches or reaches the theoretical density. In the subsequent sintering process, the workpiece can shrink evenly in all directions, achieving high-density, high-efficiency, and high-precision molding of the workpiece. Through the subsequent heat treatment system, the various properties of the workpiece can be accurately controlled, thereby enhancing the mechanical properties, wear resistance, and corrosion resistance of the workpiece.

[0026] B) The additive manufacturing system for metal powder provided by the present invention can be modified on the basis of existing equipment, and the compaction mechanism is directly arranged above the forming cylinder, which can reduce the deformation in the subsequent sintering process and the internal force between the workpiece materials, thereby reducing the number of sintering and solidification iterations, reducing the melting and sintering time, and facilitating practical application and mass production.

[0027] 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 embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 A schematic diagram of a first structure of an additive manufacturing system for metal powder provided in Embodiment 1 of the present invention;

[0030] Figure 2 A second structural schematic diagram of the additive manufacturing system for metal powder provided in the first embodiment of the present invention;

[0031] Figure 3 A flow chart of an additive manufacturing method for metal powder provided in Embodiment 2 of the present invention.

[0032] Reference numerals:

[0033] 1-compacted part; 2-single layer; 3-anti-sticking layer; 4-vibrator; 5-second vertical drive mechanism; 6-forming cylinder; 7-powder spreading mechanism; 8-binder injection mechanism; 9-displacement detector; 10-slide rail; 11-bracket; 12-pressure detector; 13-vacuum adsorption part; 14-material transition layer; 15-powder supply mechanism; 16-workbench. DETAILED DESCRIPTION

[0034] 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.

[0035] Embodiment 1

[0036] This embodiment provides an additive manufacturing system for metal powder, see Figure 1 , including a forming cylinder 6, a powder spreading mechanism 7, a binder injection mechanism 8 and a compacting mechanism. The powder spreading mechanism 7 is used to spread powder in the forming cylinder 6 to form a single layer 2, the binder injection mechanism 8 is used to inject binder into the single layer 2, and the compacting mechanism is used to compact the single layer 2 injected with binder.

[0037] It can be understood that in order to realize the driving of each of the above mechanisms, the above-mentioned additive manufacturing system for metal powder also includes a first vertical driving mechanism, a first horizontal driving structure, a second horizontal driving mechanism and a second vertical driving mechanism 5. Among them, the first vertical driving mechanism is used to drive the forming cylinder 6 to reciprocate in the vertical direction to realize the laying of multiple layers of single layer 2; the first horizontal driving mechanism is used to drive the powder spreading mechanism 7 to reciprocate horizontally, so that the powder spreading mechanism 7 leaves or is directly above the forming cylinder 6 to realize the laying of the single layer 2; the second horizontal driving mechanism is used to drive the binder injection mechanism 8 to reciprocate horizontally, so that the binder injection mechanism 8 leaves or is directly above the forming cylinder 6 to realize the binder injection; the second vertical driving mechanism 5 is used to drive the compaction mechanism to reciprocate in the vertical direction, so that the compaction mechanism is close to or away from the single layer 2 to realize the compaction of the single layer 2.

[0038] It should be noted that, in actual operation, powder spreading, binder injection and compaction are performed in sequence, so the powder spreading mechanism 7, the binder injection mechanism 8 and the compaction mechanism will not interfere with each other during the movement.

[0039] Compared with the prior art, the additive manufacturing system for metal powder provided in this embodiment is provided with a compacting mechanism specifically used to compact a single layer sprayed with a binder. Through the setting of the compacting mechanism, each time the binder is sprayed in the single layer 2, the current single layer 2 can be compacted, the voids in the single layer 2 can be reduced, the thickness of the single layer 2 can be compressed, and the compactness of the single layer 2 and the green body can be improved, so that the workpiece is close to or reaches the theoretical density. In the subsequent sintering process, the workpiece can shrink evenly in all directions, realizing high-density, high-efficiency, and high-precision molding of the workpiece. Through the subsequent heat treatment system, the various properties of the workpiece can be accurately controlled, thereby enhancing the mechanical properties, wear resistance and corrosion resistance of the workpiece.

[0040] In addition, the above-mentioned additive manufacturing system for metal powder can be modified on the basis of existing equipment, and the compaction mechanism can be directly set above the forming cylinder 6, which can reduce the deformation in the subsequent sintering process and the internal force between the workpiece materials, thereby reducing the number of sintering and solidification iterations, reducing the melting and sintering time, and facilitating practical application and mass production.

[0041] It should be noted that the above-mentioned additive manufacturing system for metal powder is particularly suitable for large-size, high-density (final size is 2 to 800 mm, specific gravity is 1 to 18 g / cm 3 ) workpiece manufacturing. This is because the bonding force of the powder in the green body of a large-sized workpiece is weak, and collapse or local damage is prone to occur during the powder cleaning or transportation process. The above-mentioned compacting mechanism is used to densify the single layer 2 and the green body. The same amount and type of binder can increase the bonding area of ​​more powders, making the bonding between powder particles tighter, thereby improving the overall bonding force of the green body, enabling it to withstand greater external forces and loads, and reducing the occurrence of collapse or local damage.

[0042] It is understandable that, in order to achieve powder supply, the above-mentioned additive manufacturing system for metal powder further includes a powder supply mechanism 15 , and a powder outlet of the powder supply mechanism 15 is connected to a powder inlet of the powder spreading mechanism 7 .

[0043] Exemplarily, the powder supply mechanism 15 is fixedly connected to the powder spreading mechanism 7 to ensure continuous powder supply to the powder spreading mechanism 7 .

[0044] In order to achieve stable installation and support of the forming cylinder 6, the above-mentioned additive manufacturing system for metal powder also includes a workbench 16 and a bracket 11. The workbench 16 is arranged on a mounting surface (for example, the ground) through the bracket 11. An installation groove for accommodating the forming cylinder 6 is opened on the workbench 16, and the forming cylinder 6 is located in the installation groove.

[0045] In order to facilitate the sliding of the powder spreading mechanism 7 and the binder injection mechanism 8, the above-mentioned additive manufacturing system for metal powder also includes a slide rail 10, which is arranged on the workbench 16, and the powder spreading mechanism 7 and the binder injection mechanism 8 are arranged on the slide rail 10 and are slidably connected to the slide rail 10.

[0046] As for the structure of the compacting mechanism, specifically, it includes a compacting member 1 (for example, a compacting plate or a compacting sheet), which is arranged directly above the single layer 2 , and the molding width of the compacting member 1 is less than or equal to the molding width of the molding cylinder 6 .

[0047] Exemplarily, the compacting element 1 is a whole block or a divided block structure, which is determined according to specific format requirements.

[0048] The compacting mechanism has a first compacting mode. When the compacting mechanism is in the first compacting mode, a non-sticking layer 3 is provided on one side of the compacting member 1 facing the single layer 2. The non-sticking layer 3 does not adhere to or partially adheres to the binder and powder in the single layer 2. In this way, by providing the non-sticking layer 3, after the single layer 2 is compacted, the compacting member 1 can be well separated from the single layer 2, and basically will not adhere to the powder and binder, thereby further ensuring the molding accuracy of the workpiece.

[0049] Exemplarily, the binder is a water-based binder, and the anti-adhesive layer 3 is a super hydrophobic coating, for example, a polytetrafluoroethylene layer, a polyperfluoroethylene propylene layer, an ethylene chlorotrifluoroethylene copolymer layer, or an ethylene-tetrafluoroethylene copolymer layer. Alternatively, a micro-nano structure is processed on one side of the compact 1 facing the monolayer 2 as the anti-adhesive layer 3, so that the water contact angle of the anti-adhesive layer 3 is greater than 150° and the sliding angle is less than 10°. The binder is an oil-based binder, and the anti-adhesive layer 3 is a super oleophobic coating, for example, a nano silica layer.

[0050] In order to further improve the compaction of the single layer 2 and the green body, the above-mentioned compacting mechanism also includes a vibrator 4 for driving the compacting part 1 to vibrate. During the compaction process, the ultrasonic vibration is assisted to further vibrate the single layer 2, thereby reducing the thickness of the single layer 2. It can achieve compaction of the single layer 2 in the opposite directions of length and width without damaging the lower single layer 2.

[0051] Exemplarily, the vibrator 2 is a multi-dimensional ultrasonic vibrator, which has the ability of adjustable frequency and amplitude, realizes ultrasonic-assisted vibration, achieves the effect of compacting the single layer 2, and prevents the adhesive or powder from adhering to the compacted part 1.

[0052] In order to detect the pressing amount of the compacting member 1 in real time and thus control the compaction degree of the single layer 2, the compacting mechanism further includes a displacement detector 9, a drive controller and a master controller.

[0053] The main controller is connected to the drive controller and the displacement detector 9 respectively, the drive controller is connected to the reciprocating drive assembly, the displacement detector 9 collects the actual displacement of the compaction part 1 in real time and transmits it to the main controller, the main controller receives the actual displacement and determines whether the actual displacement is equal to the set displacement, if it is equal, the main controller sends a stop downward movement instruction to the drive controller, the drive controller receives the stop downward movement instruction, and controls the reciprocating drive assembly to stop moving downward.

[0054] In order to detect the downward pressure of the compacting piece 1 in real time and avoid damage to the solidified single layer 2 of the lower layer, the compacting mechanism further includes a pressure detector 12 for detecting the downward pressure of the compacting piece 1 .

[0055] Correspondingly, the main controller is connected to the drive controller and the pressure detector 12 respectively, the drive controller is connected to the reciprocating drive assembly, the pressure detector 12 collects the actual downward pressure of the compacting part 1 in real time and transmits it to the main controller, the main controller receives the actual downward pressure and determines whether the actual downward pressure is equal to the set downward pressure, if equal, the main controller sends a stop downward movement instruction to the drive controller, the drive controller receives the stop downward movement instruction, and controls the reciprocating drive assembly to stop moving downward.

[0056] Based on the settings of the displacement detector 9 , the drive controller, the main controller and the pressure detector 12 .

[0057] The main controller calculates the maximum downward force of the compaction piece 1 according to the maximum compressive strength of the binder and powder after curing and the impact of the area; the reciprocating drive assembly drives the compaction piece 1 to be pressed downward, and the pressure detector 12 detects the downward force of the compaction piece 1. If the downward force reaches 90-95% of the maximum downward force, the downward force of the compaction piece 1 is stopped, and the displacement detector 9 detects the maximum downward force of the compaction piece 1; the main controller calculates the final thickness of the single layer according to the difference between the initial thickness of the single layer and the maximum downward force of the compaction piece 1; and the workpiece is sliced ​​according to the forming height and the final thickness of the single layer to obtain the number of slice layers.

[0058] Considering that the workpiece changes materials during the additive manufacturing process, that is, the powder compositions of two adjacent single layers 2 are different, in order to achieve compaction during the material conversion process, the compaction mechanism has a second compaction mode. The compaction member 1 is provided with a vacuum adsorption member 13 and a material transition layer 14 on one side facing the single layer 2. The material transition layer 14 comprises a lower layer of powder, an upper layer of powder and a solidified binder. The material transition layer 14 is connected or separated from the anti-adhesive layer 3 via the vacuum adsorption member 13. Figure 2 .

[0059] In this way, in the process of converting different materials, the vacuum adsorption part 13 adsorbs the material transition layer 14 and places the material transition layer 14 on the single layer 2. After compacting the single layer 2, the vacuum adsorption part 13 releases the material transition layer 14, and the material transition layer 14 remains on the single layer 2 as one of the layers of the workpiece, realizing the transition after the conversion of two different materials.

[0060] Embodiment 2

[0061] This embodiment provides a method for additive manufacturing of metal powder, see Figure 3 , using the additive manufacturing system for metal powder provided in Example 1, the additive manufacturing method includes the following steps:

[0062] Step 1: The powder spreading mechanism 7 is turned on and moves from the first side of the forming cylinder 6 to the second side. During the movement, powder is spread into the forming cylinder 6 to form a single layer 2.

[0063] Step 2: The powder spreading mechanism 7 is reset and closed, and the binder spraying mechanism 8 is turned on. The binder spraying mechanism 8 moves from the second side of the forming cylinder 6 to the first side, and during the movement, the binder is sprayed into the single layer 2;

[0064] Step 3: The binder spraying mechanism 8 is reset and closed, and the compacting mechanism is turned on to compact the single layer 2 sprayed with the binder;

[0065] Step 4: The compacting mechanism is reset and closed, and the forming cylinder 6 moves downward;

[0066] Step 5: Repeat steps 1 to 4 until additive manufacturing is completed.

[0067] Illustratively, the initial thickness of the single layer is 0.1 to 500 μm.

[0068] Compared with the prior art, the beneficial effects of the additive manufacturing method for metal powder provided in this embodiment are basically the same as the beneficial effects of the additive manufacturing system for metal powder provided in Example 1, and are not described in detail here.

[0069] In order to further improve the compactness of the single layer 2 and the green body, the following steps are also included between step 4 and step 5:

[0070] The compacted single layer 2 is pre-cured.

[0071] Exemplarily, in the above step 3, compacting the single layer 2 sprayed with the binder further comprises the following steps:

[0072] Step a: driving the compacting member 1 to move downward to compact and maintain the pressure of the single layer 2;

[0073] Step b: After the pressure is maintained, the compacting member 1 is driven to move upward, and the compacting member 1 is separated from the single layer 2, thereby completing the compaction of the single layer 2.

[0074] In the above step a, in the process of driving the compacting member 1 to move downward, in order to detect the downward pressure of the compacting member 1 in real time and thus control the compactness of the single layer 2, the following steps are also included:

[0075] Step a1: the displacement detector 9 collects the actual displacement of the compacting member 1 in real time and transmits it to the main controller;

[0076] Step a2: the main controller receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If so, proceed to step a3;

[0077] Step a3: the main controller sends a stop downward movement instruction to the drive controller;

[0078] Step a4: The drive controller receives the stop downward movement instruction and controls the reciprocating drive assembly to stop moving downward.

[0079] Alternatively, in the above step a, in the process of driving the compacting member 1 to move downward, in order to detect the downward force of the compacting member 1 in real time and thus control the compactness of the single layer 2, the following steps are also included:

[0080] Step a1': the pressure detector 12 collects the actual downward pressure of the compacting member 1 in real time and transmits it to the main controller;

[0081] Step a2': the main controller receives the actual downforce and determines whether the actual downforce is equal to the set downforce. If so, proceed to step a3';

[0082] Step a3': the main controller sends a stop downward movement instruction to the drive controller;

[0083] Step a4': the drive controller receives the instruction to stop moving downward, and controls the reciprocating drive assembly to stop moving downward.

[0084] The above description is only a preferred specific implementation manner 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. An additive manufacturing system for metal powder, characterized in that: It includes a forming cylinder, a powder spreading mechanism, a binder injection mechanism and a compacting mechanism; The powder spreading mechanism is used to spread powder in the forming cylinder to form a single layer; The binder spraying mechanism is used to spray the binder into the single layer; The compacting mechanism is used to compact the single layer sprayed with the binder.

2. The additive manufacturing system for metal powder according to claim 1, characterized in that: The additive manufacturing system also includes a first vertical drive mechanism, a first horizontal drive mechanism, a second horizontal drive mechanism, and a second vertical drive mechanism; The first vertical driving mechanism is used to drive the forming cylinder to reciprocate in the vertical direction; The first horizontal driving mechanism is used to drive the powder spreading mechanism to reciprocate horizontally, so that the powder spreading mechanism leaves or is located directly above the forming cylinder; The second horizontal driving mechanism is used to drive the binder injection mechanism to reciprocate horizontally, so that the binder injection mechanism leaves or is located directly above the forming cylinder; The second vertical driving mechanism is used to drive the compacting mechanism to reciprocate in the vertical direction so that the compacting mechanism approaches or moves away from the single layer.

3. The additive manufacturing system for metal powder according to claim 1, characterized in that: The additive manufacturing system also includes a powder supply mechanism, and a powder outlet of the powder supply mechanism is connected to a powder inlet of the powder spreading mechanism.

4. The additive manufacturing system for metal powder according to claim 3, characterized in that: The powder supply mechanism is fixedly connected to the powder spraying mechanism.

5. The additive manufacturing system for metal powder according to claim 1, characterized in that: The additive manufacturing system further includes a workbench and a bracket. The workbench is arranged on a mounting surface via the bracket. A mounting groove for accommodating a forming cylinder is provided on the workbench. The forming cylinder is located in the mounting groove.

6. The additive manufacturing system for metal powder according to claim 1, characterized in that: The additive manufacturing system also includes a slide rail, and the powder spreading mechanism and the binder injection mechanism are arranged on the slide rail and are slidably connected to the slide rail.

7. A method for additive manufacturing of metal powder, characterized in that: An additive manufacturing system for metal powder as claimed in any one of claims 1 to 6 is used.

8. The additive manufacturing method for metal powder according to claim 7, characterized in that: The additive manufacturing method comprises the following steps: Step 1: The powder spreading mechanism is turned on and moves from the first side of the forming cylinder to the second side. During the movement, powder is spread into the forming cylinder to form a single layer. Step 2: The powder spreading mechanism is reset and closed, and the binder spraying mechanism is turned on. The binder spraying mechanism moves from the second side of the forming cylinder to the first side, and during the movement, the binder is sprayed into the single layer; Step 3: The binder spraying mechanism is reset and closed, and the compacting mechanism is turned on to compact the single layer sprayed with the binder; Step 4: The compacting mechanism is reset and closed, and the forming cylinder moves downward; Step 5: Repeat steps 1 to 4 until additive manufacturing is completed.

9. The additive manufacturing method for metal powder according to claim 8, characterized in that: In the step 1, the initial thickness of the single layer is 0.1 to 500 μm.

10. The additive manufacturing method for metal powder according to claim 8, characterized in that: The steps between step 4 and step 5 also include the following steps: The compacted single layer is pre-cured.

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