Layering and compacting device and method for binder spraying additive manufacturing

Abstract

The invention discloses a paving layer compacting device and method for binder spraying additive manufacturing, belongs to the technical field of additive manufacturing, and aims to solve the problems of large deformation, large shrinkage rate, large self-weight influence and the like in binder spraying additive manufacturing in the prior art. The paving layer compacting device comprises a pressing plate and a reciprocating driving assembly used for driving the pressing plate to be away from or make contact with a paving layer, and the pressing plate is arranged over the paving layer; when the paving layer compacting device has the first compacting mode, the paving layer compacting device is in the first compacting mode, a surface treatment layer is arranged on the face, facing the paving layer, of the pressing plate, and the surface treatment layer is not adhered to or partially adhered to an adhesive in the paving layer. The device and the method can be used for paving and compacting of binder spraying additive manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a ply compacting device and method for binder jet additive manufacturing. Background Art

[0002] Binder Jetting (BJ) is a high-efficiency, high-precision "line scanning" 3D printing technology that uses the material system and sintering process of the traditional powder metallurgy industry. It has low cost and a high degree of material standardization, and can achieve high-efficiency, high-quality, and low-cost 3D printing.

[0003] The process of binder jetting additive manufacturing of metal, ceramic and other parts usually includes powder bed preparation, green body printing, green body curing, green body debinding and high-temperature sintering.

[0004] Since the microstructure of the component body after sintering changes from a loosely packed powder state to a tightly bonded state, a dimensional shrinkage of more than 15 to 20% will occur, resulting in problems such as large deformation and poor precision in binder jet additive manufacturing. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a ply compaction device and method for binder jetting additive manufacturing, so as to solve the problems of large deformation, large shrinkage rate, large influence of self-weight, etc. in the prior art of binder jetting additive manufacturing.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions.

[0007] The present invention provides a ply compacting device for binder jetting additive manufacturing, which is used to compact plies in a binder jetting additive manufacturing process, wherein the plies include powder and a binder;

[0008] The ply compacting device includes a pressing plate and a reciprocating drive assembly for driving the pressing plate away from or in contact with the ply, the pressing plate being arranged just above the ply;

[0009] When the ply compacting device has a first compacting mode, the ply compacting device is in the first compacting mode, a surface treatment layer is provided on a side of the pressing plate facing the ply, and the surface treatment layer is not adhered to or partially adhered to the adhesive in the ply.

[0010] Furthermore, the adhesive is a water-based adhesive, and the surface treatment layer is a super-hydrophobic coating.

[0011] Furthermore, the super hydrophobic coating is a polytetrafluoroethylene layer, a polyperfluoroethylene propylene layer, an ethylene chlorotrifluoroethylene copolymer layer or an ethylene-tetrafluoroethylene copolymer layer.

[0012] Furthermore, a micro-nano structure is processed on a side of the press plate facing the laminate as a surface treatment layer;

[0013] The water contact angle of the surface treatment layer is greater than 150°, and the sliding angle is less than 10°.

[0014] Furthermore, the adhesive is an oil-based adhesive, and the surface treatment layer is a super oleophobic coating.

[0015] Furthermore, the super oleophobic coating is a nano-silicon dioxide layer.

[0016] Furthermore, the ply compacting device also includes an ultrasonic vibrator for driving the pressing plate to vibrate.

[0017] Furthermore, the reciprocating drive assembly includes a reciprocating motor and a telescopic guide rail, one end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the other end of the telescopic guide rail is fixedly connected to the pressing plate, and the reciprocating motor drives the pressing plate to reciprocate in the vertical direction;

[0018] Alternatively, the reciprocating drive assembly includes a robot arm and a robot arm driver for driving the robot arm to reciprocate.

[0019] Furthermore, the reciprocating drive assembly is arranged above the pressing plate, the upper end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the lower end of the telescopic guide rail is fixedly connected to the upper end surface of the pressing plate;

[0020] Alternatively, the reciprocating drive assembly is arranged below the pressing plate, the lower end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the upper end of the telescopic guide rail is fixedly connected to the upper end surface of the pressing plate.

[0021] The present invention also provides a ply compaction method for binder jet additive manufacturing, which uses the ply compaction device as described above to compact the plies.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] A) The binder jetting additive manufacturing ply compacting device provided by the present invention can compact the current ply after each plying through the setting of the pressing plate, thereby reducing the voids in the ply, compressing the thickness of the ply, and improving the compactness of the ply 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, thereby achieving high-density, high-efficiency, and high-precision forming of the final workpiece. The workpiece performance can be accurately controlled through the subsequent heat treatment system, thereby enhancing the mechanical properties, wear resistance, and corrosion resistance of the workpiece.

[0024] B) The binder jet additive manufacturing ply compacting device provided by the present invention, through the provision of a surface treatment layer, can separate the pressing plate from the ply well after the ply is compacted, and basically will not be sticky to powder and binder, thereby further ensuring the forming accuracy.

[0025] C) The binder jet additive manufacturing ply compaction device provided by the present invention can be modified on the basis of the existing binder jet additive manufacturing equipment and directly arranged above the forming cylinder. It has a simple structure and can reduce 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 is easy to apply in practice and mass production.

[0026] D) The binder jetting additive manufacturing ply compacting device provided by the present invention densifies the green body. The same amount of the same type of binder can increase the bonding area of ​​more powders, thereby improving the overall bonding strength of the green body. When the device is working, it can make the bonding between powder particles tighter, enhance the bonding strength between particles, enable it to withstand greater external forces and loads, and reduce the occurrence of collapse or local damage, thereby realizing the manufacturing of large-size, high-specific-gravity workpieces.

[0027] E) The binder jet additive manufacturing ply compacting device provided by the present invention can further vibrate the ply with the aid of ultrasonic vibration during the compaction process to reduce the thickness of the ply, thereby achieving compaction of the ply in the opposite directions of length and width, while ensuring that the underlying ply is not damaged.

[0028] 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

[0029] 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.

[0030] Figure 1 A schematic diagram of the structure of a binder jetting additive manufacturing ply compacting device provided by an embodiment of the present invention in a first compacting mode, wherein a reciprocating motor is located above a pressing plate, and the direction of the arrow is the direction of movement of the pressing plate;

[0031] Figure 2A schematic diagram of the structure of a binder jetting additive manufacturing ply compacting device in a first compacting mode provided by an embodiment of the present invention, wherein the reciprocating motor is located below the pressing plate, and the direction of the arrow is the direction of movement of the pressing plate;

[0032] Figure 3 A schematic diagram of the structure of a ply compaction device for binder jet additive manufacturing provided by an embodiment of the present invention in a first compaction mode, wherein the reciprocating drive assembly is in the form of a mechanical arm, and the direction of the arrow is the direction of movement of the pressing plate;

[0033] Figure 4 A schematic structural diagram of a binder jet additive manufacturing ply compaction device in a second compaction mode provided in an embodiment of the present invention, wherein a reciprocating motor is located above a pressing plate, and the direction of the arrow is the direction of movement of the pressing plate.

[0034] Reference numerals:

[0035] 1-pressing plate; 2-laying layer; 3-surface treatment layer; 4-ultrasonic vibrator; 5-reciprocating motor; 6-telescopic guide rail; 7-mechanical arm; 8-mechanical arm driver; 9-displacement sensor; 10-drive controller; 11-master controller; 12-pressure sensor; 13-vacuum suction cup; 14-transition curing layer. DETAILED DESCRIPTION

[0036] 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.

[0037] Embodiment 1

[0038] This embodiment provides a ply compacting device for binder jetting additive manufacturing, see Figures 1 to 4 , used for compacting the ply 2 during the binder jetting additive manufacturing process, the components of the ply 2 including powder and binder.

[0039] The ply compacting device comprises a pressing plate 1 and a reciprocating driving assembly for driving the pressing plate 1 to move away from or contact the ply 2 , and the pressing plate 1 is arranged just above the ply 2 .

[0040] The ply compacting device has a first compacting mode. When the ply compacting device is in the first compacting mode, a surface treatment layer 3 is provided on one side of the press plate 1 facing the ply 2 . The surface treatment layer 3 is non-adhesive or partially adhesive to the binder and powder in the ply 2 .

[0041] Exemplarily, the adhesive is a water-based adhesive, and the surface treatment layer 3 is a super hydrophobic coating, such as a polytetrafluoroethylene layer (PTFE), a fluoroethylene propylene layer (FEP), an ethylene chlorotrifluoroethylene copolymer layer (ECTE), or an ethylene-tetrafluoroethylene copolymer layer (ETFE).

[0042] Alternatively, a micro-nano structure is processed on one side of the press plate 1 facing the laminate 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°.

[0043] 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.

[0044] Compared with the prior art, the binder jet additive manufacturing ply compacting device provided in this embodiment, on the one hand, through the setting of the pressing plate 1, can compact the current ply 2 after each ply 2, reduce the gaps in the ply 2, compress the thickness of the ply 2, and improve the compactness of the ply 2 and the green body, 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, achieving high-density, high-efficiency and high-precision forming of the workpiece, and the subsequent heat treatment system can accurately control the various properties of the workpiece, thereby enhancing the mechanical properties, wear resistance and corrosion resistance of the workpiece.

[0045] On the other hand, by providing the surface treatment layer 3, after the ply 2 is compacted, the pressing plate 1 can be well separated from the ply 2, and basically will not be adhered to by powder and adhesive, thereby further ensuring the forming accuracy of the workpiece.

[0046] On the other hand, the above-mentioned layer compaction device can be modified on the basis of the existing binder jet additive manufacturing equipment and directly arranged above the forming cylinder. It has a simple structure and can reduce 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.

[0047] It should be noted that the above-mentioned binder jet additive manufacturing ply compaction device is suitable for manufacturing any workpieces such as sand cores, metal workpieces, non-metal workpieces, etc. formed by binder jet additive manufacturing.

[0048] It is particularly suitable for the manufacture of large-sized and high-density workpieces. 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 ply compaction device manufactured by the above-mentioned binder jet additive manufacturing is used to densify the ply 2 and the green body. The same amount and type of binder can increase the bonding area of ​​more powders, making the bonding between the 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, thereby realizing the manufacture of large-sized and high-density workpieces.

[0049] For example, the final size of the large-size workpiece is 2 to 800 mm, and the specific gravity is 1 to 18 g / cm 3 .

[0050] In order to further improve the compactness of the ply 2 and the green body, the ply compacting device manufactured by binder jet additive manufacturing also includes an ultrasonic vibrator 4 for driving the pressing plate 1 to vibrate. During the compaction process, the ultrasonic vibration is assisted to further vibrate the ply 2, thereby reducing the thickness of the ply 2 and achieving compaction of the ply 2 in the opposite directions of length and width without damaging the underlying ply 2.

[0051] For the reciprocating drive assembly structure, specifically, the following two structures can be adopted:

[0052] In one structure, the reciprocating drive assembly 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 pressing plate 1, and the reciprocating motor 5 drives the pressing plate 1 to reciprocate in the vertical direction.

[0053] For example, the following two arrangements may be used for the arrangement of a reciprocating drive assembly in the form of a machine tool:

[0054] In one arrangement, the reciprocating drive assembly is arranged above the pressing 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 pressing plate 1, see Figure 1 This method makes it easier to modify existing binder jetting additive manufacturing equipment and reduces the difficulty of installing the reciprocating drive assembly.

[0055] In another way, the reciprocating drive assembly is arranged below the pressing 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 pressing plate 1, see Figure 2 By adopting this arrangement, the reciprocating drive assembly 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.

[0056] In another structure, the reciprocating drive assembly is in the form of a mechanical arm, specifically, it includes a mechanical arm 7 and a mechanical arm driver 8 for driving the mechanical arm 7 to reciprocate, see Figure 3 It should be noted that, in practical applications, a mechanical arm 7 capable of realizing the above functions can be used, which will not be described in detail here.

[0057] In order to detect the pressing amount of the pressing plate 1 in real time and thus control the compactness of the ply 2, the ply compacting device for binder jet additive manufacturing further includes a displacement sensor 9, a drive controller 10 and a master controller 11.

[0058] The main controller 11 is connected to the drive controller 10 and the displacement sensor 9 respectively. The drive controller 10 is connected to the reciprocating drive assembly. The displacement sensor 9 collects the actual displacement of the pressure plate 1 in real time and transmits it to the main controller 11. The main controller 11 receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If equal, the main controller 11 sends a stop downward movement instruction to the drive controller 10. The drive controller 10 receives the stop downward movement instruction and controls the reciprocating drive assembly to stop moving downward.

[0059] In order to detect the downward pressure of the pressing plate 1 in real time and avoid damage to the lower layer 2 after solidification, the above-mentioned binder jet additive manufacturing layer compaction device also includes a pressure sensor 12 for detecting the downward pressure of the pressing plate 1.

[0060] Correspondingly, the main controller 11 is connected to the drive controller 10 and the pressure sensor 12 respectively, the drive controller 10 is connected to the reciprocating drive assembly, the pressure sensor 12 collects the actual downward pressure of the pressure plate 1 in real time and transmits it to the main controller 11, the main controller 11 receives the actual downward pressure and determines whether the actual downward pressure is equal to the set downward pressure, if equal, the main controller 11 sends a stop downward movement instruction to the drive controller 10, the drive controller 10 receives the stop downward movement instruction, and controls the reciprocating drive assembly to stop moving downward.

[0061] Based on the setting of displacement sensor 9, drive controller 10, overall controller 11 and pressure sensor 12.

[0062] The main controller 11 calculates the maximum downward force of the pressing plate 1 according to the maximum compressive strength of the cured binder and powder and the impact area; the reciprocating drive assembly drives the pressing plate 1 to press down, and the pressure sensor 12 detects the downward force of the pressing plate 1. If the downward force reaches 90-95% of the maximum downward force, the pressing of the pressing plate 1 is stopped, and the displacement sensor 9 detects the maximum downward force of the pressing plate 1; the main controller 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 force of the pressing plate 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.

[0063] Considering that the workpiece may change its material during the additive manufacturing process, that is, the powder components in two adjacent layers 2 are different, in order to achieve compaction during the material conversion process, the ply compaction device has a second compaction mode. The ply compaction device has a second compaction mode. A vacuum suction cup 13 and a transitional solidification layer 14 are provided on one side of the press plate 1 facing the ply 2. The transitional solidification layer 14 includes a lower layer of powder, an upper layer of powder and a solidified binder. The transitional solidification layer 14 is connected or separated from the surface treatment layer 3 via the vacuum suction cup 13. Figure 4 .

[0064] In this way, in the process of converting different materials, the vacuum suction cup 13 absorbs the transition solidified layer 14 and places the transition solidified layer 14 on the ply 2. After compacting the ply 2, the vacuum suction cup 13 releases the transition solidified layer 14, and the transition solidified layer 14 remains on the ply 2 as one of the layers of the workpiece, realizing the transition after the conversion of two different materials.

[0065] Embodiment 2

[0066] This embodiment provides a binder jetting additive manufacturing ply 2 compaction method, using the compaction device of the first embodiment, including the following steps:

[0067] Step a: Turn on the reciprocating drive assembly;

[0068] Step b: the reciprocating drive assembly drives the pressing plate 1 to move downward to compact and maintain the pressure of the ply 2;

[0069] Step c: After the pressure is maintained, the reciprocating drive assembly drives the pressing plate 1 to move upward, and the pressing plate 1 is separated from the ply 2, thereby completing the compaction of the ply 2.

[0070] Compared with the prior art, the beneficial effects of the binder jet additively manufactured ply 2 compaction method provided in this embodiment are basically the same as the beneficial effects of the binder jet additively manufactured ply compaction device provided in Example 1, and are not elaborated here one by one.

[0071] In the above step b, in the process of the reciprocating drive assembly driving the pressing plate 1 to move downward, in order to detect the pressing amount of the pressing plate 1 in real time and thus control the compactness of the ply 2, the following steps are also included:

[0072] Step b1: the displacement sensor 9 collects the actual displacement of the pressing plate 1 in real time and transmits it to the main controller 11;

[0073] Step b2: the main controller 11 receives the actual displacement and determines whether the actual displacement is equal to the set displacement. If so, proceed to step b3;

[0074] Step b3: the main controller 11 sends a stop downward movement instruction to the drive controller 10;

[0075] Step b4: the drive controller 10 receives the stop downward movement instruction and controls the reciprocating drive assembly to stop moving downward.

[0076] Alternatively, in the above step b, in the process of the reciprocating drive assembly driving the pressing plate 1 to move downward, in order to detect the downward pressure of the pressing plate 1 in real time and thus control the compactness of the ply 2, the following steps are also included:

[0077] Step b1': the pressure sensor 12 collects the actual downward pressure of the pressing plate 1 in real time and transmits it to the main controller 11;

[0078] Step b2': the master controller 11 receives the actual downforce and determines whether the actual downforce is equal to the set downforce. If so, proceed to step b3';

[0079] Step b3': the main controller 11 sends a stop downward movement instruction to the drive controller 10;

[0080] Step b4': the drive controller 10 receives the instruction to stop moving downward, and controls the reciprocating drive assembly to stop moving downward.

[0081] 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 ply compacting device for binder jetting additive manufacturing, characterized in that: For compacting a ply in a binder jetting additive manufacturing process, the ply comprising a powder and a binder; The ply compacting device comprises a pressing plate and a reciprocating drive assembly for driving the pressing plate to move away from or contact the ply, wherein the pressing plate is arranged directly above the ply; The ply compacting device has a first compacting mode. When the ply compacting device is in the first compacting mode, a surface treatment layer is provided on a side of the press plate facing the ply, and the surface treatment layer is non-adhesive or partially adhesive to the adhesive in the ply.

2. The binder jetting additive manufacturing ply compacting device according to claim 1, characterized in that: The adhesive is a water-based adhesive, and the surface treatment layer is a super-hydrophobic coating.

3. The binder jetting additive manufacturing ply compacting device according to claim 2, characterized in that: The super hydrophobic coating is a polytetrafluoroethylene layer, a polyperfluoroethylene propylene layer, an ethylene chlorotrifluoroethylene copolymer layer or an ethylene-tetrafluoroethylene copolymer layer.

4. The binder jetting additive manufacturing ply compacting device according to claim 2, characterized in that: Processing a micro-nano structure on a side of the press plate facing the laminate as a surface treatment layer; The water contact angle of the surface treatment layer is greater than 150°, and the sliding angle is less than 10°.

5. The binder jetting additive manufacturing ply compacting device according to claim 1, characterized in that: The adhesive is an oil-based adhesive, and the surface treatment layer is a super oleophobic coating.

6. The binder jetting additive manufacturing ply compacting device according to claim 5, characterized in that: The super oleophobic coating is a nano silicon dioxide layer.

7. The binder jetting additive manufacturing ply compacting device according to any one of claims 1 to 6, characterized in that: The ply compacting device further comprises an ultrasonic vibrator for driving the pressing plate to vibrate.

8. The binder jetting additive manufacturing ply compacting device according to any one of claims 1 to 6, characterized in that: The reciprocating drive assembly includes a reciprocating motor and a telescopic guide rail, one end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the other end of the telescopic guide rail is fixedly connected to the pressing plate, and the reciprocating motor drives the pressing plate to reciprocate in the vertical direction; Alternatively, the reciprocating drive assembly includes a robot arm and a robot arm driver for driving the robot arm to reciprocate.

9. The binder jetting additive manufacturing ply compacting device according to claim 8, characterized in that: The reciprocating drive assembly is arranged above the pressing plate, the upper end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the lower end of the telescopic guide rail is fixedly connected to the upper end surface of the pressing plate; Alternatively, the reciprocating drive assembly is arranged below the pressing plate, the lower end of the telescopic guide rail is connected to the output end of the reciprocating motor, and the upper end of the telescopic guide rail is fixedly connected to the upper end surface of the pressing plate.

10. A binder jetting additive manufacturing ply compaction method, characterized in that: The ply is compacted using the ply compacting device as described in any one of claims 1 to 9.

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