Powder spreading structure and multi-material 3D printing system

Abstract

The present application belongs to the technical field of additive manufacturing, and particularly relates to a powder spreading structure and a multi-material 3D printing system, mainly comprising a control module, a powder outlet assembly, a fixed grid assembly and a recycling assembly. The fixed grid assembly comprises a plurality of fixed grid units arranged side by side. Each fixed grid unit comprises a fixed grid seat, a fixed grid arm and a driver. The fixed grid arm is rotatably connected to the fixed grid seat. An end of the fixed grid arm away from the fixed grid seat is provided with a notch. The driver drives the fixed grid arm to rotate in the fixed grid seat. The notch side is provided with a shielding part. The powder outlet assembly comprises a powder storage bin and a powder outlet nozzle. The powder outlet nozzle is connected to the powder storage bin. The powder outlet nozzle is used to deliver the powder material stored in the powder storage bin to the notch on the fixed grid arm. The control module is signal connected to the driver and controls the driver to adjust the angle of rotation of the fixed grid arm. The recycling assembly is used to recycle the powder material remaining on the fixed grid assembly. The present application solves the problem of difficult manufacturing of parts that need to be printed by multiple metal materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of additive manufacturing, and particularly relates to a powder spreading structure and a multi-material 3D printing system. BACKGROUND

[0002] A common 3D printing system based on laser melting technology (SLM) can usually only use one kind of powder material for printing, and can only spread the same kind of metal powder. The rigidity and strength of the printed parts are uniformly distributed overall. However, for some parts, the rigidity and strength may not be uniformly distributed in their own structure. For example, a piston is a key part of an engine, and its quality directly affects the performance of the engine. The top of the piston contacts the combustion chamber, so it requires high temperature and high pressure resistance, and higher rigidity and strength. The skirt of the piston is relatively lower in strength and rigidity from the mechanical structure, so the top and the skirt can be made of different alloys. For metal parts that need to be printed by different metal powders, the existing 3D printing system is limited by its own powder spreading structure and can only spread one kind of metal powder, making it difficult to manufacture parts that need to be printed by multiple metal materials. SUMMARY

[0003] The present application aims to provide a powder spreading structure and a multi-material 3D printing system to solve the problem of difficulty in manufacturing parts that need to be printed by multiple metal materials.

[0004] To achieve the above-mentioned purpose, one aspect of the present application provides a powder spreading structure, comprising a control module, a powder outlet assembly, a grid assembly and a recycling assembly:

[0005] The grid assembly comprises a plurality of grid units arranged side by side. The grid unit comprises a grid seat, a grid arm and a driver. The grid arm is rotatably connected in the grid seat. An opening is formed at one end of the grid arm away from the grid seat. The driver drives the grid arm to rotate in the grid seat. A shielding part is provided on the side of the opening.

[0006] The powder outlet assembly comprises a powder storage bin and a powder outlet nozzle. The powder outlet nozzle is connected to the powder storage bin. The powder outlet nozzle is used to deliver the powder material stored in the powder storage bin to the opening on the grid arm.

[0007] The control module is signal connected with the driver and controls the driver to adjust the angle of rotation of the grid arm.

[0008] The recycling assembly is used to recycle the powder material remaining on the grid assembly.

[0009] The working principle and beneficial effects of the present application are as follows:

[0010] The control module controls the rotation stroke of the sizing arm in the sizing seat by controlling the drivers of the sizing assembly, so that the end of the sizing part rotates, the gap faces upward, and the gap is combined into a certain shape, and then the powder material is released from the gap by the powder outlet assembly, so that the powder laying is completed. The excess powder material that falls and stays on the sizing assembly is recycled by the recycling assembly. Each sizing unit can form a gap independently, and multiple sizing units can control the position and size of the gap formed by the control module through stroke control, so as to form a complex pattern with multiple gaps. Therefore, the scheme is also applicable to 3D printing of parts with complex cross-sectional structures.

[0011] When laying multiple types of powder, the scheme has the following advantages: 1. Multiple powder outlet assemblies correspond to one sizing assembly: the gap of each sizing unit of the sizing assembly can be controlled independently, so that the gaps of multiple sizing units can be controlled to form a pattern, and then different powder materials are released from the gaps of the sizing units by the nozzles of different powder outlet assemblies, thereby realizing the printing of multiple metal materials; 2. Multiple powder outlet assemblies correspond to multiple sizing assemblies: each sizing assembly controls its own gap to form a pattern, and then different powder materials are released from the gaps of each sizing assembly by the nozzles of the corresponding powder outlet assemblies, thereby realizing the printing of multiple metal materials, and the efficiency is higher than that of the aforementioned one-to-many scheme.

[0012] In the scheme, the powder outlet assembly can release powder to multiple gaps simultaneously, which is efficient and thus the 3D printing system using the scheme has higher printing efficiency. More importantly, the powder outlet assembly does not need to be positioned and controlled, which greatly reduces the control difficulty of the powder outlet assembly and makes the powder outlet structure simpler and more reliable.

[0013] Compared with the traditional powder laying structure, the scheme has the following advantages: due to the ability to lay multiple types of powder locally, a part of the sizing assembly and the powder outlet assembly can accurately lay multiple metal powder materials that need to be sintered on the sintering position, and the remaining part of the sizing assembly and the powder outlet assembly can lay cheaper powder materials that are not used for part forming on the remaining positions to form the support of the metal powder materials of the part. Compared with the scheme in the prior art in which the entire layer is laid to form the powder material of the part, the recycling assembly can also recycle the powder material that stays on the sizing assembly, which can greatly reduce the consumption of the metal powder material of the part and greatly reduce the production cost.

[0014] Optionally, a walking assembly is further included, which comprises a walking driver, a walking seat, and a guide rail. The walking driver is installed on the walking seat and drives the walking seat to rotate along the guide rail. The sizing assembly is installed on the walking seat, and the walking driver is signal-connected with the control module. When the walking assembly is not included, it is more suitable for printing sheet metal (or shell) parts. When the walking assembly is combined, it is widely applicable to 3D printing of various parts.

[0015] Optionally, the driver comprises a number of servo motors corresponding to the number of the fixed arms, the output end of each servo motor is connected with one fixed arm, and the servo motors are controlled by the control module. The rotation angle of the fixed arm is controlled by the servo motor.

[0016] Optionally, the driver comprises a gear and rack mechanism, a driver motor, and a number of electromagnetic clutch pins corresponding to the number of the fixed arms. The gear and rack mechanism comprises a rack and a number of driven gears corresponding to the number of the fixed arms. The output end of the driver motor is provided with a driving gear, and the driving gear and the driven gears are engaged with the rack. The electromagnetic clutch pin comprises an electromagnetic induction part and a plug pin. The fixed arm comprises a connecting part and a rotating part, and the rotating part is rotatably connected with the fixed seat. One end of each connecting part is coaxially connected with one driven gear, and the other end of each connecting part is provided with one electromagnetic induction part and has a plug slot corresponding to the plug pin. One end of the rotating part has a connecting slot corresponding to the plug slot, and the plug pin is rotatably connected in the connecting slot. The plug pin is made of a permanent magnet, and the two magnetic levels are located on the two ends of the plug pin. The other end of the rotating part has a notch slot in the radial direction. The control module accurately controls the magnetic field generated by some electromagnetic induction parts, and controls the magnetism of the side of the magnetic field facing the plug pin. When the magnetism of the magnetic field is different from the magnetism of the end close to the plug pin, the plug pin is attracted and inserted into the connecting slot. The driver motor drives the rack to translate a distance. During the translation of the second rack, the fixed arm connected by the connecting part and the rotating part is driven to rotate by a certain angle. Until the notch slot faces the powder outlet nozzle, the powder material can be released. After the release of the powder material is completed, the driver motor is reversed again, the notch slot is reset, the direction of the notch slot changes, and the notch slot is no longer exposed. The control module controls the electromagnetic induction part corresponding to the fixed arm connected by the connecting part and the rotating part to generate an opposite magnetic field, repel the plug pin, and reset the plug pin.

[0017] Optionally, the powder outlet nozzle comprises a nozzle, which is used to spray the powder material in a conical shape when the powder material is released. This can avoid the dead angle of powder spreading caused by the shielding of the shielding part when the notch is exposed after the shielding part is rotated, and ensure the uniformity and continuity of the powder spreading.

[0018] Optionally, the powder outlet assembly comprises a powder storage pipe, an inner nozzle pipe, and an adjusting assembly. The powder storage pipe is provided with an inlet. The nozzle is arranged on the side of the powder storage pipe in the axial direction parallel to the powder storage pipe. The nozzle is a strip-shaped through hole. The inner nozzle pipe is sleeved in the powder storage pipe. The inner pipe side wall is provided with a power seam matched with the nozzle. The two ends of the inner nozzle pipe are rotatably connected with the two ends of the powder storage pipe. The adjusting assembly is connected with the end of the inner nozzle pipe and is used to adjust the distance between the power seam and the nozzle. The inner nozzle pipe is connected with an inflation nozzle. The inflation nozzle inflates the pressure gas. The gas in the power seam is taken out from the nozzle after the powder material enters the powder storage pipe, and can maintain a conical shape. The size of the powder spraying amount is controlled by adjusting the distance between the power seam and the nozzle through the adjusting assembly. The greater the distance, the greater the powder spraying amount, and the greater the thickness of the single-layer powder spreading. Conversely, the smaller the distance, the thinner the single-layer powder spreading.

[0019] Alternatively, recyclable components may include brushes or vacuum cleaners.

[0020] Optionally, the brush assembly includes a brush shaft, bristles, and a collection groove. The bristles are distributed on the side of the brush shaft, which is driven by a servo motor controlled by a control module. The collection groove is located below the brush shaft and the stationary arm.

[0021] Optionally, the vacuum cleaner includes a negative pressure tube and a solenoid valve. The negative pressure tube has several air holes on its side, which face the end of the fixed arm that forms a notch. The solenoid valve is installed at one end of the negative pressure tube and is connected to the vacuum pump. The solenoid valve is controlled by the control module.

[0022] Another aspect of the present invention is to provide a 3D printing system, including a body, a laser sintering assembly, a power supply module and a controllable lifting worktable, and employing the aforementioned powder spreading structure. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the powder spreading mechanism in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the powder-spreading structure in Embodiment 2 of the present invention;

[0025] Figure 3 This is a cross-sectional view of the powder dispensing component of the powder spreading structure in Embodiment 2 of the present invention;

[0026] Figure 4 This is a schematic diagram of a fixed unit of the powder-spreading structure in Embodiment 3 of the present invention. Detailed Implementation

[0027] The following detailed description illustrates the specific implementation method:

[0028] The markings in the accompanying drawings include: 1. Fixed base; 2. Fixed arm; 3. Servo motor; 4. Notch; 5. Powder storage bin; 6. Conveying pipe; 7. Turntable; 8. Nozzle; 9. Powder dispensing assembly; 901. Powder storage pipe; 902. Inner spray pipe; 903. Push plate; 904. Feed inlet; 905. Assist slit; 10. Linear motor; 11. Powder guide plate; 12. Electromagnetic induction part; 13. Connecting part; 14. Rotating part; 15. Slot; 16. Pin; 17. Brush shaft; 18. Baffle plate; 19. Driven gear; 20. Brush bristles; 21. Collection trough; 22. Negative pressure pipe; 23.

[0029] Example 1

[0030] The multi-material 3D printing system in this example includes a machine body, a laser sintering assembly, a power supply module, and a controllable lifting worktable. All of these components are mature existing technologies and will not be described in detail here, nor are they shown in the figures. The system includes a powder spreading structure, which comprises a control module, a powder dispensing assembly 9, a stabilization assembly, and a recycling assembly.

[0031] As attached Figure 1 As shown, in this embodiment, the grading assembly includes 32 grading units arranged side by side. Each grading unit includes a grading base 1, a grading arm 2, and a driver 3. One end of the grading arm 2 is rotatably connected to the grading base 1. A servo motor 3 drives one or more grading arms 2 to rotate 90° within the grading base 1, causing the baffle plate 18 to rotate to a vertical position with the notch 4 facing upwards. The powder outlet nozzle of the powder dispensing assembly 9 only needs to uniformly release powder to the end of the grading arm 2 with the notch 4. Some powder accumulates on the worktable through the notch 4, while some powder is blocked and retained on the grading arm 2 by the baffle plate 18 at the end of the grading arm 2, and is finally collected by the recycling assembly. In this embodiment, to ensure a neater edge of powder accumulation after powder is released from the notch 4, a baffle plate 20 is also provided at the notch 4 end of the grading arm 2. The servo motor 3 can be reset by reversing 90°.

[0032] The powder dispensing assembly 9 also includes three sets of conveying pipes 6 and a turntable 7. Each conveying pipe 6 has a strip-shaped nozzle 8 on its side, installed at the powder outlet, and always facing downwards. Powder is pumped from the powder storage hopper 5 by a pumping device and then fed into the conveying pipes 6. The pumped powder is then sprayed from the nozzles 8 at the same pressure, ensuring uniform powder distribution. A main solenoid valve and 32 conduits are located at the outlet of the pumping device. The control module controls the main solenoid valve, thereby controlling the opening and closing of the powder conveying and the conveying volume. The 32 conduits are connected to each nozzle 8. The three conveying pipes 6 are mounted on the turntable 7, which is located above the notch 4 formed by the positioning assembly. The turntable 7 is driven by another servo motor and controlled by the control module. When a specific type of powder needs to be sprayed, the conveying pipe 6 for that powder is rotated directly above the notch 4.

[0033] The control module is connected to the driver 3 and controls the driver 3 to adjust the rotation angle of the fixed arm 2. In this embodiment, the control module is a computer with input, output, calculation and storage functions. After inputting the model information of the part, the control module can automatically slice the part according to the model and analyze the distribution position of the notch 4 corresponding to each layer of the part when printing. When the fixed component cooperates with the lifting worktable to print to the layer, it sends a signal to the driver 3 to simulate the notch 4 at that point. It also controls the corresponding powder dispensing component 9 and the turntable 7 to spray out the corresponding powder to complete the powder spreading. Then, auxiliary powder is spread at the complementary position of the notch 4 in each layer (the position where the powder required for part forming has not been spread).

[0034] The recycling component is used to recover powder residue on the stationary assembly. In this embodiment, the brush assembly includes a brush shaft 17, brush bristles 21, and a collection groove 22. The brush bristles 21 are arranged in a row on the side of the brush shaft 17, which is driven by a servo motor controlled by a control module. The collection groove is located below the brush shaft 17 and the stationary arm 2. When the stationary arm 2 is reset after the powder is laid, the control module starts the servo motor to rotate the brush bristles 21, sweeping the powder residue on the stationary arm 2 into the collection groove 22 below. To prevent the powder from being recovered more smoothly, a powder guide plate 11 is also provided above the stationary arm to block the powder and, together with the brush assembly, allow the powder to fall better into the collection groove 22.

[0035] In this embodiment, since no walking component is used, 3D printing can only be completed by lifting the worktable, making it more suitable for printing sheet metal (or shell) parts with linear cross-sections.

[0036] Example 2

[0037] The difference between this embodiment and Embodiment 1 is as follows: Appendix Figure 2 As shown, it also includes a traveling assembly, enabling the stationary assembly to move as a whole perpendicular to the lifting direction of the worktable. The traveling assembly includes a traveling driver 3, a traveling seat, and a guide rail. The traveling driver 3 is mounted on the traveling seat and drives the traveling seat to rotate along the guide rail. The stationary assembly is mounted on the traveling seat, and the traveling driver 3 is signal-connected to the control module. In this embodiment, the combination of the traveling driver 3 and the guide rail is a linear motor 10, which is controlled by the control module. The traveling seat is mounted on the output end of the linear motor 10, thereby precisely controlling the displacement of the stationary assembly perpendicular to the lifting direction. Combined with the constantly changing notches 4 of the stationary assembly, 3D printing of parts with more complex cross-sections can be produced.

[0038] In other embodiments, the walking drive 3 can be an electric cylinder, hydraulic cylinder, pneumatic cylinder, electric lead screw, or other similar structure. In this embodiment, it includes two sets of positioning components, each corresponding to a powder dispensing component 9, used to lay two different metal powders for forming parts. (See attached...) Figure 3As shown, the powder dispensing assembly 9 includes a powder storage pipe 901, an inner spray pipe 902, and an adjusting assembly. The powder storage pipe 901 is provided with a feed inlet 904. In this embodiment, the feed inlet 904 is a strip-shaped through-hole. The feed inlet 904 is located below the powder storage bin 5 and is directly connected to the powder storage bin 5. The nozzle 8 is arranged on the side of the powder storage pipe 901 along a direction parallel to the axis of the powder storage pipe 901. The nozzle 8 is a strip-shaped through-hole. The inner spray pipe 902 is sleeved inside the powder storage pipe 901. The side wall of the inner pipe is provided with an assisting slit 905 that cooperates with the nozzle 8. The two ends of the inner spray pipe 902 are rotatably connected to the two ends of the powder storage pipe 901. The adjusting assembly is connected to the end of the inner spray pipe 902 and is used to adjust the distance between the assisting slit 905 and the nozzle 8. An air inlet is connected to the inner spray pipe 902. Since the feed inlet 904 in this embodiment is directly connected to the storage silo, a pusher plate 903 is installed at the feed inlet 904. The pusher plate 903 is wedge-shaped and is controlled by a miniature electric cylinder (connected to the end of the ejector plate, the end of which extends outside the powder storage silo 5, and the side wall of the powder storage silo 5 has a sliding groove). The electric cylinder is controlled by a control module and is used to push the powder material in the storage silo into the powder storage tube 901, and to block the feed inlet 904 when the powder storage tube 901 is inflated. When pressurized gas is injected into the inflation nozzle, the powder material enters the powder storage tube 901 and is carried out from the nozzle 8 by the gas rushing out of the assisted slit 905, maintaining a conical shape. The amount of powder sprayed is controlled by adjusting the distance between the assisted slit 905 and the nozzle 8 using an adjusting component. The greater the distance, the greater the amount of powder sprayed and the thicker the single layer of powder, and vice versa.

[0039] In this embodiment, the recycling component is a vacuum cleaner-type recycling component. The vacuum cleaner includes a negative pressure pipe 23 and a solenoid valve. The negative pressure pipe has 32 air holes on its side, each air hole facing one end of a notch formed by a fixed arm 2. The solenoid valve is installed at one end of the negative pressure pipe 23 and is connected to a vacuum pump. The solenoid valve is controlled by a control module. After the powder is spread, the control module activates the solenoid valve, which starts the vacuum pump, allowing the retained powder to be sucked away and recycled.

[0040] Example 3

[0041] The difference between this embodiment and Embodiment 2 is that: the driver 3 includes a gear and rack mechanism, a driver motor, and 32 electromagnetic clutch pins. The gear and rack mechanism includes a rack and 32 driven gears 19. A driving gear is mounted on the output end of the driver motor, and both the driving gear and the driven gears 19 mesh with the rack. The electromagnetic clutch pins include an electromagnetic induction part 12 and a pin 16, the pin 16 having a square cross-section. In this embodiment, the main structure of the electromagnetic induction part 12 is a conductive coil. (See attached...) Figure 4As shown, the fixed arm 2 includes a connecting part 13 and a rotating part 14. The rotating part 14 is rotatably connected to the fixed base 1. One end of each connecting part 13 is coaxially connected to a driven gear 19. The other end of each connecting part 13 is equipped with an electromagnetic induction part 12 and has a slot 15 corresponding to the pin 16. The slot 15 is square. One end of the rotating part 14 has a connecting groove corresponding to the slot 15. The connecting groove is also directional. The pin 16 is rotatably connected in the connecting groove. The pin 16 is made of a permanent magnet and the two magnetic poles are located at both ends of the pin 16. The other end of the rotating part 14 has a notch 17 in the radial direction. The control module precisely controls certain electromagnetic induction units 12 to generate a magnetic field, and controls the magnetism of the side of the magnetic field facing the pin 16. When the magnetic field is opposite to the magnetism of the end of the pin 16 closest to it, the pin 16 is attracted and inserted into the connecting slot. The driver motor drives the rack to translate a certain distance. During the translation of the second rack, the fixed arm 2 connecting the pin 16 to the connecting part 13 and the rotating part 14 rotates 90° until the notch 17 faces the powder nozzle, at which point the powder is released. In this embodiment, the nozzle 8 sprays the powder in a cone shape when releasing the powder, so that the powder can pass smoothly through the notch 4 and avoids the powder under-spread caused by dead corners. After the powder is released, the driver motor reverses, the notch 17 resets, the orientation of the notch 17 changes and it is no longer exposed, and the control module controls the electromagnetic induction units corresponding to the fixed arm 2 connecting the pin 16 to the connecting part 13 and the rotating part 14 to generate an opposite magnetic field, repelling the pin 16 and resetting it. In this embodiment, the notch 17 is composed of two parallel, eccentrically arranged baffles 18, which ensures that the notch 4 is large enough and that no gap is generated after the fixed arm 2 rotates 90°.

Claims

1. A powder-spreading structure, characterized in that: Includes a control module, powder dispensing component, grading component, and recycling component: The freeze-frame assembly includes multiple freeze-frame units arranged side by side. Each freeze-frame unit includes a freeze-frame base, a freeze-frame arm, and a driver. The freeze-frame arm is rotatably connected to the freeze-frame base. A notch is opened at the end of the freeze-frame arm away from the freeze-frame base. The driver drives the freeze-frame arm to rotate within the freeze-frame base. A blocking part is provided on the side of the notch. The powder dispensing assembly includes a powder storage bin and a powder dispensing nozzle. The powder dispensing nozzle is connected to the powder storage bin and is used to deliver the powder stored in the powder storage bin to the notch on the grid arm. The control module is connected to the driver via signals and controls the driver to adjust the rotation angle of the stationary arm; The recycling component is used to recover the powder material retained on the grading component.

2. The powder-spreading structure according to claim 1, characterized in that: It also includes a walking assembly, which includes a walking driver, a walking base, and a guide rail. The walking driver is mounted on the walking base and drives the walking base to rotate along the guide rail. The stationary assembly is mounted on the walking base. The walking driver is connected to the control module via signals.

3. The powder-spreading structure according to claim 2, characterized in that: The driver includes servo motors in a number corresponding to the number of grating arms. The output of each servo motor is connected to one grating arm, and the servo motors are controlled by the control module.

4. The powder-spreading structure according to claim 2, characterized in that: The actuator includes a gear and rack mechanism, a driver motor, and electromagnetic clutch pins corresponding to the number of fixed arms. The gear and rack mechanism includes a rack and driven gears corresponding to the number of fixed arms. A driving gear is installed on the output end of the driver motor, and both the driving gear and the driven gear mesh with the rack. The electromagnetic clutch pin includes an electromagnetic induction part and a pin. The fixed arm includes a connecting part and a rotating part. The rotating part is rotatably connected to the fixed base. One end of each connecting part is coaxially connected to a driven gear, and the other end of each connecting part is equipped with an electromagnetic induction part and has a slot corresponding to the pin. One end of the rotating part has a connecting groove corresponding to the slot, and the pin is rotatably connected in the connecting groove. The pin is made of a permanent magnet, and the two magnetic poles are located at both ends of the pin. The other end of the rotating part has a notch in the radial direction.

5. The powder-spreading structure according to claim 1, characterized in that: The powder nozzle includes a nozzle, which is used to spray the powder in a cone shape when releasing the powder.

6. The powder-spreading structure according to claim 5, characterized in that: The powder dispensing assembly includes a powder storage pipe, an inner spray pipe, and an adjustment assembly. The powder storage pipe has a feed inlet, and the nozzle is arranged on the side of the powder storage pipe along a direction parallel to the axis of the powder storage pipe. The nozzle is a strip-shaped through hole. The inner spray pipe is sleeved inside the powder storage pipe. The side wall of the inner pipe has an assist slit that cooperates with the nozzle. The two ends of the inner spray pipe are rotatably connected to the two ends of the powder storage pipe. The adjustment assembly is connected to the end of the inner spray pipe and is used to adjust the distance between the assist slit and the nozzle. An air inlet is connected to the inner spray pipe.

7. The powder-spreading structure according to claim 6, characterized in that: Recyclable components include brushes or vacuum cleaners.

8. The powder-spreading structure according to claim 6, characterized in that: The brush assembly includes a brush shaft, bristles, and a collection groove. The bristles are distributed on the side of the brush shaft, which is driven by a servo motor controlled by a control module. The collection groove is located below the brush shaft and the stationary arm.

9. The powder-spreading structure according to claim 1, characterized in that: The vacuum cleaner includes a negative pressure tube and a solenoid valve. Several air holes are opened on the side of the negative pressure tube, and the air holes face the end of the fixed arm that forms a notch. The solenoid valve is installed at one end of the negative pressure tube and is connected to the vacuum pump. The solenoid valve is controlled by the control module.

10. A multi-material 3D printing system, comprising a body, a laser sintering assembly, a power supply module, and a controllable lifting worktable, characterized in that: It adopts the powder-spreading structure as described in any one of claims 1 to 9.

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