A surface cleaning apparatus and method for additive manufacturing

Abstract

A surface cleaning device and method for additive manufacturing is disclosed. The device includes a working head, rollers, a lower body, a downward pressure mechanism, an upper body, and a moving actuator. An inert gas exhaust pipe is located at the center of the working head, and a roller mounting groove is located at the bottom of the exhaust pipe. The rollers can move up and down within the mounting groove. A sealing ring is located at the groove opening, and a blowing groove communicating with the inert gas exhaust pipe is located on the inner wall of the groove. An inert gas inlet pipe is located on the lower body. The method involves controlling the surface cleaning device to move along a predetermined trajectory at a set speed while applying downward pressure. The rollers move upward to the bottom of the groove, and the inert gas is discharged from the working head through the groove. Under positive pressure, the rollers generate friction with the surface of the deposited layer, removing the oxide layer and deposits through friction. Debris is blown away by the inert gas. After cleaning, the surface cleaning device leaves the deposited layer, the rollers move downward to tightly fit the sealing ring, and the inert gas automatically shuts off during non-cleaning operations.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, and in particular relates to a surface cleaning device and method for additive manufacturing. Background Technology

[0002] Additive manufacturing, as an emerging manufacturing technology, has advantages over traditional subtractive and equal-material manufacturing technologies, such as shorter production cycles, higher material utilization, more flexible manufacturing, and the ability to achieve near-net-shape forming of complex structural parts. Parts produced using additive manufacturing technology have been widely used in aerospace, medical, and automotive fields.

[0003] In metal additive manufacturing technology, directional energy deposition (DED) is one of the most widely used additive manufacturing technologies. Among them, the most common directional energy deposition technologies include laser powder feeding additive manufacturing (LDM) and arc wire feeding additive manufacturing (WAAM).

[0004] Because directional energy deposition (OED) technology delivers raw materials synchronously during the manufacturing process, eliminating the need for pre-setting powder and supports, it can perform deposition on substrates of any shape. This high flexibility and applicability has led to its widespread application in the additive manufacturing and additive repair of large components.

[0005] In the directional energy deposition of non-ferrous metal materials such as aluminum alloys and magnesium alloys, due to the nature of the metals themselves, they inevitably react with oxygen in the working environment, forming an oxide layer on the surface of the deposited layer. Furthermore, during the deposition process, low-boiling-point elements (such as zinc and magnesium) in the alloy will burn off, generating solid dust that adheres to the surface of the formed part.

[0006] However, in the additive manufacturing process of "layer-by-layer cladding and stacking," if the oxide film and deposits on the surface of the formed part are not treated, defects will occur inside the formed part. For example, during the remelting process in additive manufacturing, the oxide layer or deposits on the surface can enter the molten pool and act as impurities, thereby causing defects such as porosity, inclusions, and incomplete fusion within the deposited layer. The occurrence of these defects will seriously affect the mechanical properties and service life of the additively manufactured part.

[0007] Therefore, in order to obtain additively manufactured parts with good internal quality and excellent mechanical properties, it is essential to take certain measures to remove the oxide layer and deposits on the surface of the deposited layer of the part during the additive manufacturing process. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides a surface cleaning device and method for additive manufacturing. During the additive manufacturing process, the device can remove the oxide layer and deposits on the surface of the deposited layer of the formed part, reduce the generation of internal defects in the deposited layer, optimize the microstructure of the deposited layer, improve the mechanical properties of the deposited layer, and extend the service life of the additively manufactured formed part.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: a surface cleaning device for additive manufacturing, comprising a working head, a roller, a lower body, a downward pressure mechanism, an upper body, and a moving actuator; an inert gas exhaust pipe is installed at the center of the working head, and a roller mounting groove is provided at the bottom of the inert gas exhaust pipe, wherein the roller is located in the roller mounting groove and has vertical movement freedom within the roller mounting groove; a sealing ring is installed at the opening of the roller mounting groove to limit the downward movement freedom of the roller; multiple air blowing grooves are formed circumferentially on the inner wall surface of the roller mounting groove, and the air blowing grooves are connected to the inert gas exhaust pipe; the upper end of the working head is connected to the lower end of the lower body by a screw connection, and an inert gas inlet pipe is provided on the lower body, which is connected to the inert gas exhaust pipe; the upper body is fixedly mounted on the moving actuator, the downward pressure mechanism is fixedly mounted at the bottom of the upper body, and the lower body is fixedly mounted at the bottom of the downward pressure mechanism.

[0010] The mobile actuator is, but is not limited to, a six-axis articulated robot or a three-coordinate machine tool.

[0011] The downward pressure application mechanism is, but is not limited to, a pneumatic cylinder application device, a hydraulic cylinder application device, or an electric cylinder application device.

[0012] The rollers may be, but are not limited to, spherical rollers or cylindrical rollers.

[0013] A surface cleaning method for additive manufacturing, employing the aforementioned surface cleaning device for additive manufacturing, specifically involves: under the drive of a moving actuator, the entire surface cleaning device moves along a predetermined trajectory at a set speed; simultaneously, under the drive of a downward pressure applying mechanism, downward pressure is applied to the working head via the lower body. Under this downward pressure, the rollers rise to the bottom of the roller mounting groove. Inert gas is discharged from the working head through the inert gas exhaust pipe and the blowing groove. The working head generates positive pressure on the surface of the deposited layer on the formed part through the rollers, thereby... The dynamic friction coefficient between the roller and the surface of the deposit layer causes the roller to generate frictional force on the surface of the deposit layer, thereby removing the oxide layer and deposits on the surface of the deposit layer through this frictional force. At the same time, the inert gas blown out by the working head blows the oxide layer and deposit debris away from the deposit layer and the roller surface. When the cleaning work is completed, the surface cleaning device is controlled by the moving actuator to leave the deposit layer. Under the combined action of gravity and inert gas, the roller will slide down and fit tightly with the sealing ring, causing the blowing of inert gas to be blocked. The inert gas will automatically shut off when the non-cleaning work is completed.

[0014] During the surface cleaning process, the surface cleaning device is used alternately or in conjunction with the directional energy deposition device.

[0015] During the surface cleaning process, the predetermined trajectory of the surface cleaning device during movement is, but is not limited to, a serpentine trajectory, a spiral trajectory, or a zigzag trajectory.

[0016] During the surface cleaning process, the friction force is controlled by changing the dynamic friction coefficient between the roller and the surface of the deposited layer and the normal pressure.

[0017] During the surface cleaning process, the thickness of the oxide layer and deposits removed from the deposited layer surface is controlled by changing the moving speed of the moving actuator and the number of cleaning operations.

[0018] The beneficial effects of this invention are:

[0019] The additive manufacturing surface cleaning apparatus and method of the present invention removes the oxide layer and deposited substances from the surface of the deposited layer through contact and friction between the roller and the deposited layer during the directional energy deposition additive manufacturing process. At the same time, the inert gas blown out can remove the oxide layer, deposited debris and excess powder from the roller and the surface of the deposited layer, reducing the generation of internal defects in the formed part and making the mechanical properties of the additively manufactured component more excellent.

[0020] The surface cleaning apparatus and method for additive manufacturing of the present invention can improve the surface flatness of the deposited layer and enhance the forming quality and surface accuracy of the additive manufacturing structure during the directional energy deposition additive manufacturing process. After surface cleaning, the surface of the deposited layer is flatter, the surface flatness is improved, the standard deviation between the highest and lowest points of the deposited layer surface can be controlled within 1 mm, and the deviation of the centerline between adjacent deposited layers can be controlled within ±0.5 mm.

[0021] The additive manufacturing surface cleaning device and method of the present invention have a working head with a threaded connection and a detachable structure, which can replace different types of rollers for different surface cleaning needs. It can be applied to a variety of additive manufacturing applications and has good applicability.

[0022] The additive manufacturing surface cleaning device and method of the present invention, relying on a mobile actuator, can flexibly adjust the moving speed and moving trajectory of the surface cleaning device. The moving speed can be adjusted according to different additive manufacturing technology requirements to meet different cleaning requirements. It can be applied to most laser powder feeding additive manufacturing and arc wire feeding additive manufacturing scenarios through different moving trajectories.

[0023] The surface cleaning apparatus and method for additive manufacturing of the present invention can simultaneously clean the surface of the deposited layer during the directional energy deposition additive manufacturing process, effectively saving the manufacturing time of the formed parts, with a high degree of automation, which can improve the productivity of additive manufacturing and improve economic benefits. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a surface cleaning device for additive manufacturing according to the present invention;

[0025] Figure 2 This is a schematic diagram of the combined structure of the working head, roller, and inert gas exhaust pipe of the present invention;

[0026] Figure 3 This is a schematic diagram illustrating the cleaning of the deposited layer surface using the additive manufacturing surface cleaning apparatus of the present invention;

[0027] Figure 4 This is a schematic diagram of the cleaning trajectory used by the additive manufacturing surface cleaning apparatus of the present invention when cleaning the surface of the deposited layer (wherein, Figure 4 (a) shows a serpentine trajectory. Figure 4 (b) is a spiral trajectory. Figure 4 (c) is a zigzag trajectory);

[0028] In the figure, 1—working head, 2—roller, 3—lower body, 4—lower pressure application mechanism, 5—upper body, 6—moving actuator, 7—inert gas exhaust pipe, 8—roller mounting groove, 9—sealing ring, 10—air blowing groove, 11—deposit layer, 12—substrate, 13—inert gas inlet pipe, 14—oxide layer and deposits, F—positive pressure, f—friction force, V—moving speed. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1-4 As shown, a surface cleaning device for additive manufacturing includes a working head 1, a roller 2, a lower body 3, a downward pressure mechanism 4, an upper body 5, and a moving actuator 6. An inert gas exhaust pipe 7 is installed at the center of the working head 1, and a roller mounting groove 8 is formed at the bottom of the inert gas exhaust pipe 7. The roller 2 is located within the roller mounting groove 8 and has vertical movement freedom within the roller mounting groove 8. A sealing ring 9 is installed at the opening of the roller mounting groove 8 to restrict the downward movement freedom of the roller 2. The roller mounting groove 8 has multiple air-blowing grooves 10 circumferentially formed on its inner wall surface, which are connected to the inert gas exhaust pipe 7. The upper end of the working head 1 is connected to the lower end of the lower body 3 by a screw connection. An inert gas inlet pipe 13 is provided on the lower body 3, which is connected to the inert gas exhaust pipe 7. The upper body 5 is fixedly installed on the moving actuator 6, the lower pressure force application mechanism 4 is fixedly installed at the bottom of the upper body 5, and the lower body 3 is fixedly installed at the bottom of the lower pressure force application mechanism 4.

[0031] In this embodiment, the mobile actuator 6 can be a six-axis articulated robot or a three-coordinate machine tool. The downward force application mechanism 4 can be a pneumatic cylinder force application device, a hydraulic cylinder force application device, or an electric cylinder force application device. The roller 2 can be a spherical roller or a cylindrical roller.

[0032] A surface cleaning method for additive manufacturing employs the aforementioned surface cleaning device for additive manufacturing. Specifically, under the drive of the moving actuator 6, the entire surface cleaning device is controlled to move along a predetermined trajectory at a set speed. Simultaneously, under the drive of the downward pressure application mechanism 4, downward pressure is applied to the working head 1 through the lower body 3. Under the action of the downward pressure, the roller 2 moves upward to the bottom side of the roller mounting groove 8. Inert gas is discharged from the working head 1 through the inert gas exhaust pipe 7 and the blowing groove 10. The working head 1 generates positive pressure on the surface of the deposited layer 11 of the formed part through the roller 2, and then through the roller 2... The dynamic friction coefficient between the roller 2 and the surface of the deposit layer 11 causes the roller 2 to generate frictional force on the surface of the deposit layer 11, thereby removing the oxide layer and deposits on the surface of the deposit layer 11 through this frictional force. At the same time, the inert gas blown out by the working head 1 blows the oxide layer and deposit debris away from the surface of the deposit layer 11 and the roller 2. When the cleaning work is completed, the moving actuator 6 controls the surface cleaning device to leave the deposit layer 11. Under the combined action of gravity and inert gas, the roller 2 will slide down and fit tightly with the sealing ring 9, causing the blowing of inert gas to be blocked. The inert gas will automatically shut off when the non-cleaning work is completed.

[0033] During the surface cleaning process, the surface cleaning device is used alternately or in conjunction with the directional energy deposition device.

[0034] During the surface cleaning process, the predetermined trajectory of the surface cleaning device during movement is, but is not limited to, a serpentine trajectory, a spiral trajectory, or a zigzag trajectory.

[0035] During the surface cleaning process, the friction force is controlled by changing the dynamic friction coefficient and normal pressure between the roller 2 and the surface of the deposit layer 11.

[0036] During the surface cleaning process, the thickness of the oxide layer and the thickness of the residue removal layer on the surface of the deposited layer 11 are controlled by changing the moving speed of the moving actuator 6 and the number of cleaning operations.

[0037] In this embodiment, a 200mm×200mm×20mm magnesium alloy substrate 12 is first prepared and the surface of the substrate 12 is polished. Then, the polished magnesium alloy substrate 12 is fixed on the worktable of the directional energy deposition apparatus. At the same time, magnesium alloy powder is prepared. Before formal use, the magnesium alloy powder is dried and then supplied to the directional energy deposition apparatus.

[0038] In the data modeling software, a 200mm×150mm×50mm part is modeled. The modeled part is then sliced ​​into layers. The single-layer printing thickness of each deposition layer 11 is set to 2mm, and the printing trajectory of each deposition layer 11 is set to a zigzag trajectory.

[0039] Based on the pre-set single-layer printing thickness and printing trajectory of the deposition layer 11, select rollers 2 with appropriate shape, surface roughness and size, and screw the working head 1 with the selected rollers 2 onto the lower body 3 of the surface cleaning device. Set the initial height of the surface cleaning device to 10mm to 50mm from the surface of the substrate 12. The running trajectory of the surface cleaning device is exactly the same as the printing trajectory of each deposition layer 11, and is also set as a zigzag trajectory. At the same time, the moving speed of the surface cleaning device is set to 5mm / s.

[0040] The directional energy deposition device is started and moves on the surface of the magnesium alloy substrate 12 according to the set printing trajectory. The magnesium alloy powder melts into a molten pool and then cools to form a deposition layer 11. The corresponding parameters of laser directional energy deposition are: power of 1200W, scanning speed of 5mm / s, and powder feeding speed of 2g / min.

[0041] The surface cleaning device is started. First, the moving actuator 6 moves the surface cleaning device to the starting position of the cleaning movement trajectory. Then, the downward pressure mechanism 4 is activated, so that the roller 2 generates a positive pressure F of 500N to 2000N on the surface of the deposit layer 11 of the formed part. Then, the surface cleaning device is controlled to move according to the set moving speed V and zigzag trajectory. The frictional force f generated during the movement of the roller 2 will cause the oxide layer and the adhering material 14 on the surface of the deposit layer 11 to detach. The inert gas blown out by the working head 1 will blow away the detached oxide layer and adhering material debris. After the surface cleaning device completes the set number of cleaning cycles, the surface cleaning device is controlled to leave the deposit layer 11.

[0042] Repeat the above printing and cleaning process. After each deposition layer 11 is printed, the surface of the deposition layer 11 is cleaned. When the last deposition layer 11 is printed and the surface of the last deposition layer 11 is cleaned, the additive manufacturing of the formed part is completed.

[0043] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A surface cleaning device for additive manufacturing, characterized in that: The machine includes a working head, rollers, a lower body, a downward pressure applying mechanism, an upper body, and a moving actuator. An inert gas exhaust pipe is installed at the center of the working head. A roller mounting groove is formed at the bottom of the inert gas exhaust pipe, and the roller is located within the roller mounting groove, having vertical movement freedom within the groove. A sealing ring is installed at the opening of the roller mounting groove to limit the downward movement freedom of the roller. Multiple air-blowing grooves are formed circumferentially on the inner wall of the roller mounting groove, and these grooves are connected to the inert gas exhaust pipe. The upper end of the working head is connected to the lower end of the lower body by a screw connection. An inert gas inlet pipe is provided on the lower body, and the inert gas inlet pipe is connected to the inert gas exhaust pipe. The upper body is fixedly mounted on the moving actuator, the downward force application mechanism is fixedly mounted on the bottom of the upper body, and the lower body is fixedly mounted on the bottom of the downward force application mechanism. The moving actuator is a six-axis articulated robot or a three-coordinate machine tool. The downward force application mechanism is a pneumatic cylinder force application device, a hydraulic cylinder force application device, or an electric cylinder force application device. The rollers are spherical rollers or cylindrical rollers.

2. A surface cleaning method for additive manufacturing, employing the surface cleaning apparatus for additive manufacturing as described in claim 1, characterized in that... Specifically, driven by the mobile actuator, the entire surface cleaning device moves along a predetermined trajectory at a set speed. Simultaneously, driven by the downward pressure mechanism, the lower body applies downward pressure to the working head. Under the action of the downward pressure, the rollers move upward to the bottom of the roller mounting groove. Inert gas is discharged from the working head through the inert gas exhaust pipe and the blowing groove. The working head generates positive pressure on the surface of the deposited layer of the formed part through the rollers. Then, through the dynamic friction coefficient between the rollers and the surface of the deposited layer, the rollers generate friction on the surface of the deposited layer. Thus, the oxide layer and deposits on the surface of the deposited layer are removed by the friction force. At the same time, the inert gas blown out by the working head blows the oxide layer and deposit debris away from the deposited layer and the roller surface. After the cleaning work is completed, the surface cleaning device is controlled by the mobile actuator to leave the deposit layer. The roller will slide down under the combined action of gravity and inert gas and fit tightly with the sealing ring, which will block the blowing of inert gas. The inert gas will automatically shut off when the non-cleaning work is completed.

3. The surface cleaning method for additive manufacturing according to claim 2, characterized in that: During the surface cleaning process, the surface cleaning device is used alternately or in conjunction with the directional energy deposition device.

4. The surface cleaning method for additive manufacturing according to claim 2, characterized in that: During the surface cleaning process, the predetermined trajectory of the surface cleaning device during movement is, but is not limited to, a serpentine trajectory, a spiral trajectory, or a zigzag trajectory.

5. The surface cleaning method for additive manufacturing according to claim 2, characterized in that: During the surface cleaning process, the friction force is controlled by changing the dynamic friction coefficient between the roller and the surface of the deposited layer and the normal pressure.

6. The surface cleaning method for additive manufacturing according to claim 2, characterized in that: During the surface cleaning process, the thickness of the oxide layer and deposits removed from the deposited layer surface is controlled by changing the moving speed of the moving actuator and the number of cleaning operations.

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