Green compact method for powder binder jet 3D printing

Abstract

The invention discloses a green body compacting method for powder binder spraying 3D printing, belongs to the technical field of powder 3D printing, and aims to solve the problem that in the prior art, compacting treatment cannot be performed after single-layer slices are laid in the 3D printing process. The method comprises the steps that a reciprocating compacting plate is provided, surface treatment is conducted on the working face of the reciprocating compacting plate, and the working face subjected to surface treatment is not or partially adhered to an adhesive and powder in a single-layer slice; a reciprocating compacting plate is arranged over the single-layer slice, and the working face of the reciprocating compacting plate faces the single-layer slice; the reciprocating compacting plate is driven to move downwards, and compacting and pressure maintaining are conducted on the single-layer slices; and after pressure maintaining, the reciprocating compacting plate is driven to move upwards, the reciprocating compacting plate is separated from the single-layer slices, and compacting treatment of the single-layer slices is completed. The method can be used for compacting green bodies for powder binder jet 3D printing.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder 3D printing, and in particular relates to a green compact densification method for powder binder jet 3D printing. Background Art

[0002] Powder binder jet 3D printing is a 3D printing technology that stacks powder layer by layer, lays each single layer of slices, bonds them with a liquid binder, and finally sinters them to form the final part.

[0003] In order to facilitate the penetration of the binder into the single-layer slice, the single-layer slice cannot be compacted after laying. After spraying the binder, due to the certain viscosity of the binder, if it is compacted, the binder and powder will stick to the compacted part together, resulting in deformation of the single-layer slice or even failure of the entire 3D printing. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a green compaction method for powder binder jet 3D printing, so as to solve the problem in the prior art that a single layer of slices cannot be compacted after laying during the 3D printing process.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions.

[0006] The present invention provides a green compact densification method for powder binder jet 3D printing, comprising the following steps:

[0007] Step 1: providing a reciprocating compacting plate, and performing surface treatment on the working surface of the reciprocating compacting plate, so that the working surface after the surface treatment is not adhered to or partially adhered to the binder and powder in the single-layer slice;

[0008] Step 2: Place the reciprocating compacting plate directly above the single-layer slice, with the working surface of the reciprocating compacting plate facing the single-layer slice;

[0009] Step 3: Drive the reciprocating compacting plate downward to compact and maintain the pressure of the single-layer slices;

[0010] Step 4: After the pressure is maintained, the reciprocating densifying plate is driven to move upward, and the reciprocating densifying plate is separated from the single-layer slice, thereby completing the densification process of the single-layer slice.

[0011] Furthermore, in step 3, the process of driving the reciprocating compacting plate to move downward also includes the following steps:

[0012] Step 31: The displacement detection component collects the actual displacement of the reciprocating compacting plate in real time and transmits it to the main control unit;

[0013] Step 32: the main control unit receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If so, proceed to step b3; if not, continue to drive the reciprocating compacting plate downward;

[0014] Step 33: The main control unit sends a stop downward movement instruction to the drive control unit;

[0015] Step 34: The driving control unit receives the instruction to stop moving downward, and controls the reciprocating compacting plate to stop moving downward.

[0016] Furthermore, in step 3, the process of driving the reciprocating compacting plate to move downward also includes the following steps:

[0017] Step 31': the pressure detection component collects the actual downward pressure of the reciprocating compacting plate in real time and transmits it to the main control unit;

[0018] Step 32': the main control unit receives the actual downforce and determines whether the actual downforce is equal to the set downforce. If so, proceed to step b3'; if not, continue to drive the reciprocating compacting plate downward;

[0019] Step 33': the main control unit sends a stop downward movement instruction to the drive control unit;

[0020] Step 34 ′: the driving control unit receives the instruction to stop moving downward, and controls the reciprocating compacting plate to stop moving downward.

[0021] Furthermore, in step 3, before driving the reciprocating compacting plate to move downward, the following steps are also included:

[0022] The total control unit calculates the maximum downward force of the reciprocating compacting plate according to the maximum compressive strength of the adhesive and powder after curing and the impact of the area.

[0023] Furthermore, in step 3, the downward movement speed of the reciprocating compacting plate is 0.8 to 200 mm / min.

[0024] Furthermore, the upward movement speed of the reciprocating compacting plate is 2 to 200 mm / min.

[0025] Furthermore, in step 3, the ratio of the downward pressure of the reciprocating densifying plate to the thickness of the single-layer slice before densification is less than or equal to 1:4.

[0026] Furthermore, in step 3, the ratio of the downward pressure of the reciprocating densifying plate to the thickness of the single-layer slice before densification is 1:5 to 1:4.5.

[0027] Furthermore, in step 3, the holding time is 0.5 to 1.0 s.

[0028] Furthermore, the green compaction method of powder binder jet 3D printing uses a green compaction device.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] A) The green compaction method for powder binder jet 3D printing provided by the present invention can perform a compaction treatment on the current single-layer slice after each single-layer slice is laid through the setting of a reciprocating compaction plate, thereby reducing the pores between the powders in the single-layer slice and improving the compactness of the single-layer slice and the green compact, so that the parts are close to or reach the theoretical density, and realize high-density, high-efficiency and high-precision forming of the parts.

[0031] B) The green compaction densification method for powder binder jet 3D printing provided by the present invention, through surface treatment of the reciprocating densification plate, makes the working surface after the surface treatment not stick to or partially stick to the binder and powder in the single-layer slice. After the single-layer slice is densified, the reciprocating densification plate can be separated from the single-layer slice, and basically will not stick to the powder and binder, thereby being able to further ensure the forming accuracy of the parts.

[0032] 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

[0033] 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.

[0034] Figure 1 A flow chart of a green compact densification method for powder binder jet 3D printing provided in Example 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the first structure of a green compacting device used in the green compacting method for powder binder jet 3D printing provided in the first embodiment of the present invention, wherein the direction of the arrow is the direction of movement of the reciprocating compacting plate;

[0036] Figure 3 A second structural schematic diagram of a green body densification device used in the green body densification method for powder binder jet 3D printing provided in the first embodiment of the present invention.

[0037] Reference numerals:

[0038] 1-reciprocating compacting plate; 2-single-layer slice; 3-surface treatment layer; 4-multi-dimensional ultrasonic instrument; 5-reciprocating motor; 6-telescopic guide rail; 7-vacuum suction cup; 8-transition solidification layer; 9-displacement detection part; 10-drive control unit; 11-general control unit; 12-pressure detection part; 13-vacuum suction cup; 14-transition solidification layer. DETAILED DESCRIPTION

[0039] 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.

[0040] Embodiment 1

[0041] This embodiment provides a green compacting method for powder binder jet 3D printing, see Figure 1 , including the following steps:

[0042] Step 1: providing a reciprocating compacting plate 1, and performing surface treatment on the working surface of the reciprocating compacting plate 1, so that the working surface after the surface treatment is not adhered to or partially adhered to the binder and powder in the single-layer slice 2;

[0043] Step 2: Place the reciprocating densifying plate 1 directly above the single-layer slice 2, with the working surface of the reciprocating densifying plate 1 facing the single-layer slice 2;

[0044] Step 3: driving the reciprocating compacting plate 1 to move downward to compact and maintain the pressure of the single-layer slice 2;

[0045] Step 4: After the pressure is maintained, the reciprocating densifying plate 1 is driven to move upward, and the reciprocating densifying plate 1 is separated from the single-layer slice 2, thereby completing the densification process of the single-layer slice 2.

[0046] Compared with the prior art, the green body densification method of powder binder jet 3D printing provided in this embodiment, on the one hand, through the setting of the reciprocating densification plate 1, can densify the current single-layer slice 2 after each single-layer slice 2 is laid, reduce the pores between the powder in the single-layer slice 2, and improve the compactness of the single-layer slice 2 and the green body, so that the parts are close to or reach the theoretical density, and realize high-density, high-efficiency and high-precision forming of the parts.

[0047] On the other hand, by treating the surface of the reciprocating densifying plate 1, the working surface after the surface treatment will not stick to or will partially stick to the binder and powder in the single-layer slice 2. After the single-layer slice 2 is densified, the reciprocating densifying plate 1 can be separated from the single-layer slice 2, and basically will not stick to the powder and binder, thereby further ensuring the forming accuracy of the parts.

[0048] In order to detect the downward pressure of the reciprocating compacting plate 1 in real time and thus control the compactness of the single-layer slice 2, in the above step 3, the process of driving the reciprocating compacting plate 1 downward also includes the following steps:

[0049] Step 31: The displacement detection member 9 collects the actual displacement of the reciprocating compacting plate 1 in real time and transmits it to the general control unit 11;

[0050] Step 32: the main control unit 11 receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If so, step b3 is performed; if not, the reciprocating compacting plate 1 is continuously driven to move downward.

[0051] Step 33: the general control unit 11 sends a stop downward movement instruction to the drive control unit 10;

[0052] Step 34: The driving control unit 10 receives the instruction to stop moving downward, and controls the reciprocating compacting plate 1 to stop moving downward.

[0053] Alternatively, in order to detect the downward pressure of the reciprocating compacting plate 1 in real time and thus control the compactness of the single-layer slice 2, in the above step 3, the process of driving the reciprocating compacting plate 1 downward may further include the following steps:

[0054] Step 31': the pressure detection element 12 collects the actual downward pressure of the reciprocating compacting plate 1 in real time and transmits it to the general control unit 11;

[0055] Step 32': the main control unit 11 receives the actual downforce and determines whether the actual downforce is equal to the set downforce. If so, step b3' is performed; if not, the reciprocating compacting plate 1 is continuously driven to move downward.

[0056] Step 33': the general control unit 11 sends a stop downward movement instruction to the drive control unit 10;

[0057] Step 34 ′: the driving control unit 10 receives the instruction to stop moving downward, and controls the reciprocating compacting plate 1 to stop moving downward.

[0058] In order to avoid the reciprocating compacting plate 1 from pressing down too fast and causing damage to the solidified single-layer slice 2 of the lower layer, illustratively, in the above step 3, the downward movement speed of the reciprocating compacting plate 1 is set to be gradually reduced by 2 to 200 mm / min, and when the distance from the upper layer of powder is 0.5 mm, the downward movement speed is reduced to 0.8 to 5 mm / min.

[0059] Accordingly, from the perspective of the efficiency of the compaction process, the upward movement speed of the reciprocating compaction plate 1 is 2 to 200 mm / min.

[0060] Similarly, in order to avoid excessive downward pressure and damage to the lower solidified single-layer slice 2, illustratively, in the above step 3, the ratio of the downward pressure to the thickness of the single-layer slice 2 before densification is less than or equal to 1:4.

[0061] Exemplarily, the ratio of the pressing amount to the thickness of the single-layer slice 2 before densification is 1:5 to 1:4.5.

[0062] In order to ensure the density of the single-layer slice 2 after densification, in the above step 3, the holding time is 0.5 to 1.0 s.

[0063] Based on the configuration of the displacement detection member 9, the drive control unit 10, the general control unit 11 and the pressure detection member 12, the above step 3 includes the following steps:

[0064] Step A: The general control unit 11 calculates the maximum downward force of the reciprocating compacting plate 1 according to the maximum compressive strength of the cured binder and powder and the impact of the area. Considering the weight of the powder cylinder, the downward force needs to decrease layer by layer according to the height;

[0065] Step B: driving the reciprocating compacting plate 1 to press downward, the pressure detection member 12 detects the downward pressure of the reciprocating compacting plate 1, if the downward pressure reaches 90-95% of the maximum downward pressure, the reciprocating compacting plate 1 is stopped from pressing downward, and the displacement detection member 9 detects the maximum downward pressure of the reciprocating compacting plate 1;

[0066] Step C: the overall control unit 11 calculates the final thickness of the single layer according to the difference between the initial thickness of the single layer and the maximum downward pressure of the reciprocating compacting plate 1; and re-slices the part according to the forming height and the final thickness of the single layer to obtain the corrected number of slice layers.

[0067] Considering that the material of the part changes during the additive manufacturing process, that is, the powder composition of two adjacent single-layer slices 2 is different, in order to achieve the compaction during the material conversion process, see Figure 3 , the above steps 2 to 4 include the following steps:

[0068] Step a: placing the reciprocating densifying plate 1 directly above the single-layer slice 2, with the working surface of the reciprocating densifying plate 1 facing the single-layer slice 2;

[0069] Step b: arranging a vacuum suction cup 7 and a transition solidification layer 8 on the working surface, and the vacuum suction cup 7 adsorbs the transition solidification layer 8;

[0070] Step c: driving the reciprocating compacting plate 1 to move downward, compacting and pressurizing the single-layer slice 2 through the transition solidification layer 8, and bonding the transition solidification layer 8 to the single-layer slice 2;

[0071] Step d: After the pressure is maintained, the vacuum suction cup 7 releases the transition solidified layer 8, drives the reciprocating densifying plate 1 to move upward, and the reciprocating densifying plate 1 and the vacuum suction cup 7 are separated from the transition solidified layer 8, thereby completing the densification process of the single-layer slice 2.

[0072] In this way, in the process of converting different materials, the vacuum suction cup 7 absorbs the transition solidified layer 8 and places the transition solidified layer 8 on the single-layer slice 2. After the single-layer slice 2 is compacted, the vacuum suction cup 7 releases the transition solidified layer 8, and the transition solidified layer 8 remains on the single-layer slice 2 as one of the layers of the part, realizing the transition after the conversion of two different materials.

[0073] Exemplarily, the green compaction method of the powder binder jet 3D printing uses a green compaction device having the following structure:

[0074] Specifically, see Figure 2 The green compacting device includes a reciprocating compacting plate 1 and a telescopic motor. The output end of the telescopic motor is fixedly connected to the reciprocating compacting plate 1 to drive the reciprocating compacting plate 1 to move away from or contact the single-layer slice 2.

[0075] Exemplarily, the adhesive is a water-based adhesive, and the surface treatment layer 3 is a super-hydrophobic coating.

[0076] For example, the super hydrophobic coating is one of a polytetrafluoroethylene layer (PTFE), a fluoroethylene propylene layer (FEP), an ethylene chlorotrifluoroethylene copolymer layer (ECTE), and an ethylene-tetrafluoroethylene copolymer layer (ETFE).

[0077] Alternatively, a micro-nano structure is processed on one side of the reciprocating dense plate 1 facing the single-layer slice 2 as the surface treatment layer 3, so that the water contact angle of the surface treatment layer 3 is greater than 150° and the sliding angle is less than 10°.

[0078] The adhesive is an oil-based adhesive, and the surface treatment layer 3 is a super oleophobic coating, for example, a nano silicon dioxide layer.

[0079] In order to further improve the compactness of the single-layer slice 2 and the green body, the green body densification equipment manufactured by the above-mentioned binder jet additive manufacturing also includes a multi-dimensional ultrasonic device 4. The multi-dimensional ultrasonic device 4 is used to drive the reciprocating densification plate 1 to vibrate in multiple dimensions. During the densification process, the auxiliary ultrasonic vibration can further vibrate the single-layer slice 2 to reduce the thickness of the single-layer slice 2. It can achieve the compaction of the single-layer slice 2 in the opposite directions of length and width without damaging the lower single-layer slice 2.

[0080] For the telescopic motor structure, specifically, the following two structures can be adopted:

[0081] In one structure, the telescopic motor is in the form of a machine tool, including a reciprocating motor 5 and a telescopic guide rail 6, one end of the telescopic guide rail 6 is connected to the output end of the reciprocating motor 5, and the other end of the telescopic guide rail 6 is fixedly connected to the reciprocating dense plate 1, and the reciprocating motor 5 drives the reciprocating dense plate 1 to reciprocate in the vertical direction.

[0082] For example, the following two arrangements can be used for the arrangement of the telescopic motor in the form of a machine tool:

[0083] In one arrangement, the telescopic motor is arranged above the reciprocating compacting plate 1, the upper end of the telescopic guide rail 6 is connected to the output end of the reciprocating motor 5, and the lower end of the telescopic guide rail 6 is fixedly connected to the upper end surface of the reciprocating compacting plate 1, see Figure 2 .

[0084] By adopting this method, it is more convenient to modify the existing binder jetting additive manufacturing equipment and can reduce the difficulty of installing the telescopic motor.

[0085] In another way, the telescopic motor is arranged below the reciprocating dense plate 1, the lower end of the telescopic guide rail 6 is connected to the output end of the reciprocating motor 5, and the upper end of the telescopic guide rail 6 is fixedly connected to the upper end surface of the reciprocating dense plate 1.

[0086] By adopting this arrangement, the telescopic motor is integrated into the existing binder jetting additive manufacturing equipment, which can effectively reduce the overall height of the binder jetting additive manufacturing equipment and thus reduce the overall volume of the binder jetting additive manufacturing equipment.

[0087] In another structure, the telescopic motor is in the form of a robotic arm, specifically, it includes a robotic arm and a robotic arm driver for driving the robotic arm to reciprocate. It should be noted that in actual applications, a robotic arm that can achieve the above functions can be used, and the specific robotic arm structure is not described here one by one.

[0088] In order to be able to detect the downward pressure of the reciprocating densifying plate 1 in real time and thus control the compactness of the single-layer slice 2, the green compacting equipment manufactured by the above-mentioned binder jet additive manufacturing also includes a displacement detection part 9, a drive control unit 10 and a general control unit 11, wherein the general control unit 11 is respectively connected to the drive control unit 10 and the displacement detection part 9, and the general control unit 11 is connected to the telescopic motor through the drive control unit 10.

[0089] In order to be able to detect the downward pressure of the reciprocating densifying plate 1 in real time and avoid damage to the single-layer slice 2 after the lower layer is solidified, the above-mentioned binder jet additive manufacturing green compact densification equipment also includes a pressure detection component 12 for detecting the downward pressure of the reciprocating densifying plate 1. Accordingly, the general control unit 11 is respectively connected to the drive control unit 10 and the pressure detection component 12, and the general control unit 11 is connected to the telescopic motor through the drive control unit 10.

[0090] 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. A green compact densification method for powder binder jet 3D printing, characterized in that: The steps include: Step 1: providing a reciprocating compacting plate, and performing surface treatment on the working surface of the reciprocating compacting plate, so that the working surface after the surface treatment is not adhered to or partially adhered to the binder and powder in the single-layer slice; Step 2: Place the reciprocating compacting plate directly above the single-layer slice, with the working surface of the reciprocating compacting plate facing the single-layer slice; Step 3: Drive the reciprocating compacting plate downward to compact and maintain the pressure of the single-layer slices; Step 4: After the pressure is maintained, the reciprocating densifying plate is driven to move upward, and the reciprocating densifying plate is separated from the single-layer slice, thereby completing the densification process of the single-layer slice.

2. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In step 3, the process of driving the reciprocating compacting plate to move downward also includes the following steps: Step 31: The displacement detection component collects the actual displacement of the reciprocating compacting plate in real time and transmits it to the main control unit; Step 32: the main control unit receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If so, proceed to step b3; if not, continue to drive the reciprocating compacting plate downward; Step 33: The main control unit sends a stop downward movement instruction to the drive control unit; Step 34: The driving control unit receives the instruction to stop moving downward, and controls the reciprocating compacting plate to stop moving downward.

3. The green compaction method of powder binder jet 3D printing according to claim 1, characterized in that: In step 3, the process of driving the reciprocating compacting plate to move downward also includes the following steps: Step 31': the pressure detection component collects the actual downward pressure of the reciprocating compacting plate in real time and transmits it to the main control unit; Step 32': the main control unit receives the actual downforce and determines whether the actual downforce is equal to the set downforce. If so, proceed to step b3'; if not, continue to drive the reciprocating compacting plate downward; Step 33': the main control unit sends a stop downward movement instruction to the drive control unit; Step 34 ′: the driving control unit receives the instruction to stop moving downward, and controls the reciprocating compacting plate to stop moving downward.

4. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In the step 3, before driving the reciprocating compacting plate to move downward, the following steps are also included: The total control unit calculates the maximum downward force of the reciprocating compacting plate according to the maximum compressive strength of the adhesive and powder after curing and the impact of the area.

5. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In step 3, the downward movement speed of the reciprocating compacting plate is 0.8 to 200 mm / min.

6. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: The upward moving speed of the reciprocating compacting plate is 2-200 mm / min.

7. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In step 3, the ratio of the downward pressure of the reciprocating densifying plate to the thickness of the single-layer slice before densification is less than or equal to 1:

4.

8. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In the step 3, the ratio of the downward pressure of the reciprocating densifying plate to the thickness of the single-layer slice before densification is 1:5 to 1:4.

5.

9. The green compact densification method of powder binder jet 3D printing according to claim 1, characterized in that: In step 3, the holding time is 0.5 to 1.0 s.

10. The green compact densification method of powder binder jet 3D printing according to any one of claims 1 to 9, characterized in that: The green compaction densification method of the powder binder jet 3D printing adopts a green compaction device.

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