Composite material manufacturing equipment for space environment

Abstract

The invention discloses composite material manufacturing equipment facing space environment in the technical field of space manufacturing, which comprises a controller, a support frame, a working platform and a photoetching assembly, the photoetching assembly is fixed on the support frame, the support frame is fixedly connected with an adsorption assembly, the working platform is located in the motion trail of the photoetching assembly and the adsorption assembly, and the adsorption assembly is fixedly connected with the controller. The adsorption assembly, the photoetching assembly and the working platform are electrically connected with the controller; the working platform comprises a working table, a working groove is formed in the top of the working table, a discharging assembly is arranged in the working groove, a printing groove and a plurality of storage grooves are formed in the bottom of the working groove from left to right, a first telescopic rod is fixedly connected to the bottom of the printing groove, a working plate is fixedly connected to the top of the first telescopic rod, and a plurality of first electromagnets are evenly arranged in the working plate. The device is simple and easy to operate, and the printing raw materials can be uniformly and stably laid on the printing substrate through cooperative work of the controller, the photoetching assembly, the adsorption assembly, the workbench and the discharging assembly, so that the printing precision is improved.

Description

Technical Field

[0001] The invention belongs to the field of space manufacturing technology, and in particular is a composite material manufacturing device for space environment. Background Art

[0002] With the continuous development of aerospace technology, human exploration of space is becoming more and more in-depth, and the performance requirements for spacecraft are becoming higher and higher. In this context, composite materials and composite manufacturing technology have gradually received attention due to their unique advantages. Composite materials have excellent properties such as high strength, high stiffness, low density, corrosion resistance, and high temperature resistance, which can meet the use requirements of spacecraft in extreme environments. Composite manufacturing technology can realize the precise manufacturing of complex structural parts and improve the overall performance of spacecraft. Composite manufacturing is an advanced manufacturing technology that integrates multiple processes, tools or energy sources to achieve the processing and forming of materials through synchronous work or synergy. This technology significantly improves the flexibility and efficiency of the manufacturing process, and can produce products with complex structures and excellent performance.

[0003] At the same time, as one of the composite manufacturing technologies for space, 3D printing technology can quickly manufacture the required parts and tools according to mission requirements, thereby improving the flexibility and autonomy of missions. Through space manufacturing, the transportation cost from the earth to space can be reduced, thereby reducing the total cost of the mission. Moreover, on distant planets such as the moon and Mars, 3D printing technology can manufacture parts and tools that adapt to the environment according to actual needs, providing strong guarantees for the smooth progress of missions.

[0004] Some composite material manufacturing equipment currently used in space environments uses jet airflow to lay the 3D printing materials on the printing area and then performs 3D printing by laser curing layer by layer. When the airflow contacts the printing substrate, a certain degree of turbulence will be generated. Since the printing environment is a microgravity environment, these turbulences will have a great impact on the uniformity of the materials laid on the substrate. Therefore, it is necessary to propose a composite material manufacturing equipment for space environments that can lay the printing materials evenly and stably on the printing substrate to improve printing accuracy. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a composite material manufacturing equipment for space environment. The present invention is simple and easy to operate. Through the coordinated work of the controller, photolithography component, adsorption component, workbench and material discharge component, the printing raw materials can be evenly and stably laid on the printing substrate to improve the printing accuracy.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: A composite material manufacturing device for a space environment, comprising a controller, a support frame, a working platform and a device for curing printed materials, a photolithography component is mounted on the support frame, an adsorption component for cleaning printed materials is mounted on the support frame, the working platform is within the motion trajectory of the photolithography component and the adsorption component, and the adsorption component, the photolithography component and the working platform are all electrically connected to the controller; The working platform includes a working table, a working groove is opened on the top of the working table, a plurality of slide rails are fixedly connected to the two inner side walls in the length direction of the working groove, a material discharge component which slides with the slide rails is arranged in the working groove, a printing groove and a plurality of material storage grooves are arranged at the bottom of the working groove along its width direction, a first telescopic rod is fixedly connected to the bottom of the printing groove, a working plate is fixedly connected to the top of the first telescopic rod, the working plate slides with the printing groove, a plurality of first electromagnets are evenly arranged inside the working plate, and the first electromagnets are electrically connected to the controller.

[0007] The principle of the basic solution is: the support frame is used to support, fix and position the photolithography component, the adsorption component is used to clean and classify the printing materials in the working tank for recycling, and the discharge component is used to spread the magnetic raw material dust required for 3D additive printing on the working plate, and the first electromagnet is used to stabilize the dust in the printing area, and then the photolithography component is used to solidify or sinter the dust.

[0008] The beneficial effects of the basic scheme are: 1. The magnetic metal powder or other magnetic powder to be 3D printed is adsorbed on the working plate by the first electromagnet, thereby reducing the possibility that the dust is extremely unstable in position under microgravity in space.

[0009] 2. The design of the adsorption component can clean up and recycle unused powder at the end of printing, saving costs and reducing the burden of manual cleaning; and when multiple materials are stacked and printed in sequence, the previous material can be cleaned to facilitate the placement of the next material, thereby reducing the possibility of mixing different materials.

[0010] 3. The design of the discharge assembly and the first telescopic rod ensures that after each layer of powder is printed, the powder can be continuously laid, while ensuring that the height of the stacked powder is always equal to or lower than the bottom of the working tank, thereby ensuring that the powder stacked in the printing tank will not spread around.

[0011] Furthermore, the photolithography assembly includes a first robot arm and a laser emitter, the first robot arm is detachably connected to the laser emitter, and both the first robot arm and the laser emitter are electrically connected to the controller.

[0012] The beneficial effects of the basic scheme are: through the multi-degree-of-freedom rotation of the first robotic arm, the position of the laser emitter on its hand in space is adjusted to ensure that the laser emitter can accurately complete the production of the required components; the powder layer is laser solidified or sintered by the laser emitter to complete the corresponding printed object.

[0013] Furthermore, the adsorption component includes a second robotic arm and a negative pressure machine. The input end of the negative pressure machine is connected to a straw. The bottom of the second robotic arm is detachably connected to the straw. The output end of the negative pressure machine is connected to a recovery component. The second robotic arm and the negative pressure machine are both electrically connected to the controller.

[0014] The beneficial effects of the basic scheme are: through the multi-degree-of-freedom rotation of the second robot arm, the position of the straw on its hand in space is adjusted, and the negative pressure machine is used to generate negative pressure to clean the dust raw materials in the printing tank.

[0015] Furthermore, the discharge assembly includes a moving block and several servo motors, the servo motors are all located inside the moving block, and several slide grooves corresponding to the slide rails are opened on both sides of the length direction of the moving block, and the top and bottom of the slide grooves are respectively rotatably connected to several driven wheels and several driving wheels driven by servo motors, and the servo motors are all electrically connected to the controller; a groove is opened at the bottom of the moving block, and a second telescopic rod is fixedly connected to the top wall of the groove, and a discharge plate is fixedly connected to the lower end of the second telescopic rod, and several second electromagnets are evenly arranged inside the discharge plate, and the second electromagnets are all electrically connected to the controller.

[0016] The beneficial effects of the basic scheme are: through the rolling cooperation between the driving wheel and the driven wheel in the slide rail and the slide groove, the moving block can move along the slide rail, and the servo motor can accurately control the moving block to move to the position corresponding to the printing slot and the storage slot; the discharge plate is raised or lowered by the second telescopic rod, and the powder is taken and discharged by opening and closing the second electromagnet.

[0017] Furthermore, a material storage plate is fixedly connected to the bottom of the material storage trough, and a first magnetic attraction layer is arranged in an array at the bottom of the material storage plate, and the first magnetic attraction layer is electrically connected to the controller.

[0018] The beneficial effect of the basic solution is: the material to be printed is placed in the storage trough to facilitate continuous material laying, and the material in the storage trough is stabilized in the storage trough through the magnetic absorption layer to prevent these printing powders from floating around in the microgravity environment and affecting the normal operation of other components.

[0019] Furthermore, the controller uses pulses to control the first electromagnet.

[0020] The beneficial effect of the basic solution is: by adjusting the pulse parameters (width, frequency and amplitude), the magnetic force of the first electromagnet is adjusted, so as to complete the subsequent printing stabilization, cleaning and recycling of raw materials.

[0021] Furthermore, the lengths and widths of the unloading plate, the working plate and the material storage plate are all equal.

[0022] The beneficial effect of the basic solution is that the length and width of the discharge plate, the working plate and the storage plate are designed to be equal, which can ensure that the powder is evenly spread on the working plate each time, thereby improving the printing accuracy.

[0023] Furthermore, the controller controls the laser emitter in a pulse manner.

[0024] The beneficial effect of the basic solution is that by controlling the laser emitter with pulses, the powder printing in the designated area can be completed more accurately and quickly, thereby ensuring the integrity and accuracy of the final product, while also reducing the waste of raw materials and saving costs.

[0025] Furthermore, the diameter of the end of the straw close to the second mechanical arm is greater than the diameter of the end of the straw close to the negative pressure machine.

[0026] The beneficial effect of the basic solution is that the diameter of the end of the straw close to the second robotic arm is larger than the diameter of the end of the straw close to the negative pressure machine, which can facilitate the adsorption and cleaning of powder in some smaller areas, improve powder recovery efficiency and save costs.

[0027] Furthermore, the recovery component includes a reversing valve connected to the output end of the negative pressure machine, the reversing valve is connected to a plurality of recovery tanks, the inner walls of the recovery tanks are provided with a second magnetic attraction layer, and the second magnetic attraction layer is electrically connected to the controller.

[0028] The beneficial effect of the basic solution is: negative pressure is generated by the negative compressor to suck the powder that needs to be recycled and cleaned into the recycling tank. At the same time, based on the type of material used, these powders are classified and collected back into the corresponding recycling tank through the reversing valve, and then the recycled powders are accumulated in the recycling tank through the second magnetic attraction layer, thereby reducing the possibility of these powders being scattered and difficult to handle when they are recovered in a microgravity environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is an axonometric view of the composite material manufacturing equipment for the space environment in this embodiment.

[0030] Figure 2 This is a front cross-sectional view of the working platform of the composite material manufacturing equipment for space environment in this embodiment.

[0031] Figure 3 This is a front cross-sectional view of the unloading assembly of the composite material manufacturing equipment for space environment in this embodiment.

[0032] Figure 4 This is a front cross-sectional view of the recovery component of the composite material manufacturing equipment for space environment in this embodiment.

[0033] List of reference numerals: 1. Support frame; 2. Second robot arm; 3. Workbench; 4. Moving block; 5. Slide rail; 6. Laser transmitter; 7. First robot arm; 8. Working slot; 9. Printing slot; 10. Working plate; 11. First electromagnet; 12. First telescopic rod; 13. Material storage slot; 14. Material storage plate; 15. First magnetic layer; 16. Driving wheel; 17. Driven wheel; 18. Second telescopic rod; 19. Material discharge plate; 20. Second electromagnet; 21. Recovery tank; 22. Second magnetic layer; 23. Reversing valve. DETAILED DESCRIPTION

[0034] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Example 1

[0035] Basically as attached Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown: A composite material manufacturing device for a space environment, comprising a controller, a support frame 1, a working platform and a photolithography component for curing printed materials, the photolithography component is mounted on the support frame 1, an adsorption component for cleaning printed materials is mounted on the support frame 1, the working platform is within the motion trajectory of the photolithography component and the adsorption component, and the adsorption component, the photolithography component and the working platform are all electrically connected to the controller; The working platform includes a working table 3, and a working groove 8 is opened on the top of the working table 3; a plurality of slide rails 5 are fixedly connected to the two inner side walls of the working groove 8 in the length direction by screws; a material discharge component slidably matched with the slide rail 5 is arranged in the working groove 8, and a printing groove 9 and a plurality of material storage grooves 13 are respectively arranged at the bottom of the working groove 8 along its width direction; a material storage plate 14 is adhesively fixedly connected to the bottom of the material storage groove 13; a first magnetic attraction layer 15 is arranged in an array at the bottom of the material storage plate 14; the first magnetic attraction layer 15 is electrically connected to the controller, and a first telescopic rod 12 is fixedly connected to the bottom of the printing groove 9 by screws; a working plate 10 is fixedly connected to the top of the first telescopic rod 12 by screws; the working plate 10 is slidably matched with the printing groove 9, and a plurality of first electromagnets 11 are evenly arranged inside the working plate 10; the first electromagnets 11 are electrically connected to the controller; and the controller adopts pulse control to control the first electromagnet 11.

[0036] The photolithography assembly includes a first mechanical arm 7 and a laser emitter 6; the first mechanical arm 7 is screw-connected to the laser emitter 6, and both the first mechanical arm 7 and the laser emitter 6 are electrically connected to a controller; the controller controls the laser emitter 6 in a pulse manner.

[0037] The adsorption component includes a second robotic arm 2 and a negative pressure machine. The input end of the negative pressure machine is connected to a straw. The bottom of the second robotic arm 2 is connected to the straw screw. The output end of the negative pressure machine is connected to a recovery component. The second robotic arm 2 and the negative pressure machine are both electrically connected to the controller.

[0038] The discharge assembly includes a moving block 4 and a plurality of servo motors, the servo motors are all located inside the moving block 4, a plurality of slide grooves corresponding to the slide rails 5 are provided on both sides of the length direction of the moving block 4, a plurality of driven wheels 17 and a plurality of driving wheels 16 driven by servo motors are rotatably connected to the top and bottom of the slide grooves respectively, and the servo motors are all electrically connected to the controller; a groove is provided at the bottom of the moving block 4, a second telescopic rod 18 is fixedly connected to the top wall of the groove by screws; a discharge plate 19 is fixedly connected to the lower end of the second telescopic rod 18 by screws; a plurality of second electromagnets 20 are evenly arranged inside the discharge plate 19; and the second electromagnets 20 are all electrically connected to the controller.

[0039] The recovery component includes a reversing valve 23 connected to the output end of the negative pressure machine, and the reversing valve 23 is connected to a plurality of recovery tanks 21; the inner walls of the recovery tanks 21 are each provided with a second magnetic attraction layer 22, and the second magnetic attraction layer 22 is electrically connected to the controller.

[0040] The specific implementation process is as follows. First, a powder material to be 3D printed is placed in the corresponding storage tank 13. Due to the microgravity environment, if the dust material is not restrained, it will float in the storage tank 13, and the slight air flow will cause these powders to diffuse and escape from the storage tank 13, and even the floating magnetic powder will affect the normal operation of other components; and because the moving block 4 and the discharge plate 19 will cause a large flow of air above the storage tank 13 during operation, it will also drive the air flow above it to cause the printing powder material to escape, so that these magnetic powder materials are adsorbed and accumulated in the storage tank 13 through the first magnetic absorption layer 15, thereby ensuring the normal progress of magnetic powder 3D printing and the stability of the device.

[0041] Then the controller controls the servo motor to rotate, so that the driving wheel 16 and the driven wheel 17 slide along the slide rail 5, and then the moving block 4 moves to the top of the storage tank 13, and then the controller controls the second telescopic rod 18 to move, so that the discharge plate 19 lightly presses the magnetic powder to ensure that the top of the accumulated dust is parallel to the bottom of the discharge plate 19, thereby ensuring that the magnetic dust can be evenly adsorbed on the bottom of the discharge plate 19 during subsequent adsorption; then the discharge plate 19 is lifted and separated from the top of the accumulated powder by 1 to 2 cm, and then the second electromagnet 20 is started, and the magnetic force of the second electromagnet 20 and the first magnetic attraction layer 15 are controlled by the controller at the same time, to ensure that the discharge plate 19 can evenly adsorb 10-30 micron magnetic powder.

[0042] After the raw material adsorption is completed, the controller controls the servo motor to move the moving block 4 to the top of the working plate 10, and then the second telescopic rod 18 moves the discharge plate 19 to a distance of 1-2 cm from the working plate 10 or the top of the dust pile, and at the same time controls the first telescopic rod 12 to move the working plate 10 through the controller, so that the discharge plate 19 discharges materials in the printing slot 9 each time, thereby improving the uniformity of dust laying; then the first magnetic absorption layer 15 is closed, and the pulse parameters (frequency, amplitude, width) of the first electromagnet 11 are adjusted and controlled to increase the magnetic force of the first electromagnet 11 instantly, so that the magnetic powder on the discharge plate 19 is quickly and evenly adsorbed on the surface of the working plate 10, thereby improving the accuracy of subsequent printing. In the process of layer-by-layer printing, the controller will also control the magnetic force of the first electromagnet 11 to gradually increase, so as to ensure that the magnetic attraction of the first electromagnet 11 on the top of the accumulated powder in the printing slot 9 is always greater than the magnetic attraction of the first magnetic absorption layer 15, thereby ensuring that the top of the accumulated magnetic powder in the printing slot 9 will not be offset during the printing work, thereby ensuring the accuracy of the final product.

[0043] After the magnetic powder is evenly and stably laid on the work plate 10, the controller controls the movement of the first robot arm 7 based on the preset 3D printing model data, thereby adjusting the posture of the laser emitter 6 in the hand of the first robot arm 7. At the same time, the laser emitter 6 is pulse-controlled by the controller to ensure that the laser emitter 6 can quickly and accurately perform corresponding laser irradiation curing or sintering processing on the preset area, thereby reducing material waste.

[0044] When it is necessary to use different materials to perform composite printing on the printing component, these magnetic powder raw materials or raw material powders that have been magnetized are placed in the corresponding storage tank 13 respectively, and these powders are constrained and accumulated in the storage tank 13 by the first magnetic absorption layer 15, and the accumulated powders are pressed flat one by one by the discharge plate 19 to ensure that they can be uniformly adsorbed later. Since the excess materials need to be recycled after printing, when printing multiple materials, it is necessary to clean and recycle the previous printing material, and then add the subsequent powder material to ensure that different materials are mixed for subsequent use. Therefore, after the printing of one material is completed, the movement of the second mechanical arm 2 is controlled by the controller, so that the straw of the hand of the second mechanical arm 2 moves to the printing tank 9, and the negative pressure machine is started at the same time to suck away the powder in the printing tank 9. Since the negative pressure machine is connected to the recovery tank 21, the sucked powder will enter the corresponding recovery tank 21, and the second magnetic absorption layer 22 will confine the powder in the recovery tank 21. Then, the magnetic force of the second electromagnet 20 in the discharge plate 19 is increased, so that the amount of the next powder material adsorbed by the discharge plate 19 increases, and then the next powder is quickly filled into the printing slot 9 until the accumulated powder is parallel to the last plane printed by the previous material, and then subsequent printing is started to complete composite 3D printing of multiple materials.

[0045] At the same time, when printing with multiple materials, in order to avoid mixing of different materials after cleaning and recycling, each time a pair of powder is cleaned and recycled, the controller will control the reversing valve 23 to connect the negative pressure machine and the corresponding recovery tank 21, so as to avoid mixing of different materials during recycling. Example 2

[0046] The difference from the above embodiment is that, as shown in the attached Figure 3 and Figure 4 As shown, the length and width of the unloading plate 19, the working plate 10 and the storage plate 14 are all equal.

[0047] The specific implementation process is as follows: since the length and width of the discharge plate 19 are equal to those of the storage plate 14, and when the discharge plate 19 moves to overlap with the storage plate 14, the discharge plate 19 can evenly adsorb the magnetic powder raw material in the storage trough 13 on the bottom of the discharge plate 19, and then move to overlap with the working plate 10 to discharge the material, thereby ensuring that the above-mentioned dust is evenly laid on the working plate 10 to ensure the printing accuracy; at the same time, it can also avoid that part of the powder is adsorbed through the gap between the discharge plate 19 and the storage trough 13 and adsorbed on the four sides of the discharge plate 19 in the height direction, thereby reducing the possibility of affecting the uniformity of the powder subsequently laid in the printing trough 9. Example 3

[0048] The difference from the above embodiment is that, as shown in the attached Figure 2As shown: the diameter of the end of the straw close to the second mechanical arm 2 is larger than the diameter of the end of the straw close to the negative pressure machine.

[0049] The specific implementation process is as follows: Since the structure of some printing components is relatively complex, the powder in some areas is not easy to clean when cleaning and recovering the powder. Therefore, the diameter of the end of the straw close to the second robot arm 2 is larger than the diameter of the end of the straw close to the negative pressure machine, ensuring that the powder can be adsorbed while also being able to adsorb and recover dust in some relatively small areas.

[0050] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above technical features.

Claims

1. A composite material manufacturing equipment for space environment, characterized by: The invention comprises a controller, a support frame (1), a working platform and a photolithography component for curing printing materials, wherein the photolithography component is mounted on the support frame (1), an adsorption component for cleaning printing materials is mounted on the support frame (1), the working platform is within the motion trajectory of the photolithography component and the adsorption component, and the adsorption component, the photolithography component and the working platform are all electrically connected to the controller; the working platform comprises a working table (3), a working groove (8) is formed on the top of the working table (3), a plurality of slide rails (5) are fixedly connected to both inner side walls in the length direction of the working groove (8), a material discharge component slidably matched with the slide rails (5) is arranged in the working groove (8), a printing groove (9) and a plurality of material storage grooves (13) are respectively arranged at the bottom of the working groove (8) along its width direction, a first telescopic rod (12) is fixedly connected to the bottom of the printing groove (9), a working plate (10) is fixedly connected to the top of the first telescopic rod (12), the working plate (10) is slidably matched with the printing groove (9), a plurality of first electromagnets (11) are evenly arranged inside the working plate (10), and the first electromagnets (11) are all electrically connected to the controller.

2. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The photolithography component comprises a first mechanical arm (7) and a laser emitter (6), the first mechanical arm (7) and the laser emitter (6) being detachably connected, and the first mechanical arm (7) and the laser emitter (6) are both electrically connected to a controller.

3. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The adsorption component comprises a second mechanical arm (2) and a negative pressure machine, the input end of the negative pressure machine is connected to a suction pipe, the bottom of the second mechanical arm (2) is detachably connected to the suction pipe, the output end of the negative pressure machine is connected to a recovery component, and the second mechanical arm (2) and the negative pressure machine are both electrically connected to a controller.

4. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The material discharge assembly comprises a moving block (4) and a plurality of servo motors. The moving block (4) is provided with a plurality of slide grooves corresponding to the slide rails (5) on both sides in the length direction. The top and bottom of the slide grooves are respectively rotatably connected to a plurality of driven wheels (17) and a plurality of driving wheels (16) driven by the servo motors. The servo motors are electrically connected to a controller. The moving block (4) is provided with a groove at the bottom. A second telescopic rod (18) is fixedly connected to the top wall of the groove. A material discharge plate (19) is fixedly connected to the lower end of the second telescopic rod (18). A plurality of second electromagnets (20) are evenly arranged inside the material discharge plate (19). The second electromagnets (20) are electrically connected to the controller.

5. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The bottom of the material storage trough (13) is fixedly connected to a material storage plate (14), the bottom of the material storage plate (14) is provided with a first magnetic attraction layer (15) in an array, and the first magnetic attraction layer (15) is electrically connected to the controller.

6. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The controller uses pulses to control the first electromagnet (11).

7. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The length and width of the unloading plate (19), the working plate (10) and the material storage plate (14) are all equal.

8. The composite material manufacturing equipment for space environment according to claim 2, characterized in that: The controller controls the laser emitter (6) in a pulse mode.

9. The composite material manufacturing equipment for space environment according to claim 3, characterized in that: The diameter of the end of the straw close to the second mechanical arm (2) is larger than the diameter of the end of the straw close to the negative pressure machine.

10. The composite material manufacturing equipment for space environment according to claim 1, characterized in that: The recovery component comprises a reversing valve (23) connected to the output end of the negative pressure machine, the reversing valve (23) is connected to a plurality of recovery tanks (21), the inner walls of the recovery tanks (21) are each provided with a second magnetic attraction layer (22), and the second magnetic attraction layer (22) is each electrically connected to the controller.

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