A multi-material 3D printer and printing method thereof

Abstract

The present invention relates to a multi-material 3D printer and a printing method thereof, comprising a molding device, a powder spreading and suction device and a control device; the molding device comprises a molding chamber, a laser scanning head, a powder supply assembly, and a molding cylinder and a molding platform located in the molding chamber; the powder spreading and suction device comprises a powder spreading box, a scraper, a powder spreading assembly, a powder suction assembly and a translation assembly; the powder spreading box is located above the top plane of the molding cylinder and can be controllably reciprocated along the X-axis direction of the top plane of the molding cylinder; the translation assembly is arranged on the powder spreading box, the translation assembly is arranged along the Y-axis direction of the top plane of the molding cylinder, and is provided with a slidable mounting block; the powder spreading assembly and the powder suction assembly are arranged on the mounting block; the scraper is fixed to the bottom of the powder spreading box corresponding to the powder spreading assembly. The multi-material 3D printer realizes precise powder spreading according to the specified area through the coordinated movement of the powder spreading box and the translation assembly in the X-axis and Y-axis directions, which greatly reduces the ineffective supply of powder during the printing process.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a multi-material 3D printer and a printing method thereof. Background Art

[0002] 3D printing, also known as additive manufacturing, is based on digital model files, using materials such as powdered metal or filamentary plastic as molding materials, and constructing objects by printing layer by layer. Its part structure design is not limited by traditional processing technology, and various complex surface features can be processed relatively quickly.

[0003] At present, laser 3D printing technologies based on the principle of powder bed fusion mainly include selective laser melting (SLM) and selective laser sintering (SLS). This type of technology generally uses a scraper or roller to lay the powder layer by layer in the molding area, and then uses a laser beam to selectively melt or sinter the powder in the molding area to solidify it. After that, the next layer of powder is laid and solidified again. In this way, the three-dimensional entity is accumulated layer by layer. In the molding process, in addition to being used to mold parts, the remaining powder accumulated on the molding platform also plays the role of filling the molding platform to provide powder support or even part support for the laying of the next layer of powder.

[0004] At present, when printing a certain material area in the multi-material laser selective melting 3D printing process, the powder laying work basically requires laying a whole layer of powder for printing and cleaning up the excess powder to re-lay the heterogeneous powder; and in the process of cleaning up the excess powder, it is often necessary to clean up almost all the powder in the current layer that has not been laser selectively melted, including the powder that plays a powder support role. This will cause the amount of powder to be used in the printing process to be artificially high, and most of the powder is recycled into the powder collection chamber instead of being used for the manufacture of parts, and the powder utilization rate is low; and the powder recycling process cannot completely clean up the excess powder in certain corners, causing these excess powders to be mixed into the next laser selective melting of heterogeneous powders, affecting the part molding accuracy and reducing the molding quality. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a multi-material 3D printer and a printing method thereof that can accurately lay powder in a designated area to achieve additive manufacturing of heterogeneous materials in different layers and additive manufacturing of heterogeneous materials in the same layer.

[0006] The present invention is achieved through the following scheme:

[0007] A multi-material 3D printer, comprising:

[0008] Forming device, powder laying and suction device and control device;

[0009] The molding device comprises a molding chamber, a laser scanning head, a powder supply assembly, a molding cylinder body and a molding platform located in the molding chamber, the powder supply assembly is connected to a powder supply port at the top of the molding chamber, the laser scanning head is located directly above the molding platform, and the molding platform is escalably arranged inside the molding cylinder body;

[0010] The powder spreading and suction device comprises a powder spreading box, a scraper, a powder distribution assembly, a powder suction assembly and a translation assembly; the powder spreading box is located above the top plane of the molding cylinder, and can be controllably reciprocated along the X-axis direction of the top plane of the molding cylinder; the translation assembly is arranged on the powder spreading box, the translation assembly comprises a linear guide and a first driving source, the linear guide is arranged along the Y-axis direction of the top plane of the molding cylinder, the linear guide is provided with a slidable mounting block, and the first driving source is used to drive the mounting block; the powder distribution assembly and the powder suction assembly are arranged on the mounting block; the powder distribution assembly is used to receive powder from the powder supply assembly and discharge powder; the powder suction assembly is used to absorb powder; the scraper is fixed to the bottom of the powder spreading box corresponding to the powder distribution assembly;

[0011] The control device controls the operation of the powder laying and absorbing device and the forming device.

[0012] Furthermore, the first driving source is a synchronous belt transmission driving assembly, and the mounting block is fixed on a synchronous belt of the synchronous belt transmission driving assembly.

[0013] Furthermore, the powder distributing assembly includes a powder distributing nozzle, a second driving source and a powder blocking plate, the powder distributing nozzle is installed on the mounting block, a powder receiving port is provided at the top of the powder distributing nozzle, a powder distributing port is provided at the bottom of the powder distributing nozzle, the bottom of the powder distributing nozzle is located above the top plane of the forming cylinder body, the second driving source is provided at the outside of the powder distributing nozzle, the powder blocking plate is provided in the inner cavity of the powder distributing nozzle and is connected to the output end of the second driving source.

[0014] Furthermore, a vibration motor is arranged on the outer side of the top of the powder dispensing nozzle.

[0015] Furthermore, the top of the powder dispensing nozzle is funnel-shaped.

[0016] Furthermore, the powder suction assembly includes a powder suction nozzle, which is installed on the mounting block, and the powder distribution nozzle and the powder suction nozzle are arranged on opposite sides of the mounting block. The powder suction nozzle is located in front of the powder spreading box body along the X-axis direction, and the top of the powder suction nozzle is connected to the outside of the molding room through a pipe and connected to an external recovery device, and the bottom of the powder suction nozzle is located above the top plane of the molding cylinder.

[0017] Furthermore, the powder supply assembly includes multiple powder supply funnels, multiple powder supply branch pipes and a powder supply main pipe. The multiple powder supply funnels are correspondingly connected to one end of the multiple powder supply branch pipes, the other ends of the multiple powder supply branch pipes are connected to one end of the powder supply main pipe, and the other end of the powder supply main pipe is connected to the powder supply port at the top of the molding chamber.

[0018] Furthermore, a vibration motor is arranged outside the powder feeding main pipe.

[0019] Furthermore, a cleaning brush is provided on the wall plate of the molding chamber, and the cleaning brush is located at the end position of the moving path of the scraper.

[0020] The present invention also includes a printing method of a multi-material 3D printer, comprising the following steps:

[0021] S10: Assume that each layer of the multi-material part includes at least one material region. If there are multiple material regions, the material composition of each material region is different. Assume that the 3D printing process of the multi-material part is controlled by a control device. Place multiple powder materials in different powder supply funnels respectively.

[0022] S20: The molding platform descends a layer thickness;

[0023] S30: The control device moves the powder distribution component of the powder distribution and suction device to the bottom of the powder supply port according to the material type required by the current printing material area, and controls the powder material in the corresponding powder supply hopper to fall into the powder distribution component in a quantitative manner;

[0024] S40: The powder distribution component moves to the top of the molding platform, and controls the translation component to move while advancing to the preset current material area, so that the powder flows down to the current material area of ​​the molding platform, and the scraper spreads the powder onto the molding platform. The powder distribution component continues to translate to the top of the recycling box, and the excess powder is dumped into the recycling box; the control device directs the laser beam through the laser scanning head to selectively melt or sinter the powder material according to the scanning data of the current printing material area;

[0025] S50: The control device executes the residual powder cleaning program; the powder suction component starts to return above the recycling box, and when the powder suction component returns to the current molding area, the powder suction component is started, and the translation component is controlled to move, so that the powder suction component moves in the next printing material area to remove the residual powder in the area;

[0026] S60: Determine whether the current layer is printed. If not, repeat steps S30 to S60. If it is completed and the current layer is not the last layer, repeat steps S20 to S60. If it is completed and the current layer is the last layer, the printing of the multi-material part is completed.

[0027] Compared with the prior art, the multi-material 3D printer of the present invention has the following beneficial effects:

[0028] 1. A multi-material 3D printer of the present invention realizes precise powder spreading in a designated area by coordinating the movement of a powder spreading box and a translation component in the X-axis and Y-axis directions, thereby greatly reducing the ineffective supply of powder during the printing process and realizing additive manufacturing of heterogeneous materials of different layers and additive manufacturing of heterogeneous materials of the same layer.

[0029] 2. A multi-material 3D printer of the present invention, by arranging a powder distribution nozzle and a powder suction nozzle on opposite sides of a mounting block, can accurately remove powder from a designated area, realize regionalized powder distribution and powder suction, and greatly improve the working efficiency of the printer. At the same time, only one powder distribution and suction device is needed in the molding chamber, which reduces the overall volume of the printer and makes the structure more compact.

[0030] 3. In a multi-material 3D printer of the present invention, after each material area is formed, the excess powder outside the material area can be cleaned up, thereby preventing the mixing of the currently printed material into the next printing of heterogeneous materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of a multi-material 3D printer provided by the present invention;

[0032] Figure 2 for Figure 1 A schematic diagram of the structure of a powder-laying and suction device;

[0033] Figure 3 for Figure 2 Forward schematic diagram of

[0034] Figure 4 for Figure 1 A schematic diagram of the structure of a powder supply component;

[0035] Figure 5 This is a schematic diagram of the powder receiving state of the powder suction device;

[0036] Figure 6 It is a schematic diagram of the powder laying state of the powder absorbing device;

[0037] Figure 7 This is a schematic diagram of the cleaning scraper state of the powder suction device;

[0038] Figure 8 This is a schematic diagram of the powder absorbing state of the powder absorbing device;

[0039] Fig. 9 A schematic diagram of material distribution of a forming layer of a part processed according to an embodiment of the present invention;

[0040] In the figure: 10, molding chamber; 11, laser scanning head; 12, powder supply assembly; 121, powder supply funnel; 122, powder delivery branch pipe; 123, powder delivery main pipe; 13, powder spreading and suction device; 131, powder spreading box; 132, scraper; 133, linear guide; 134, first driving source; 1341, synchronous belt; 135, powder distribution nozzle; 136, second driving source; 137, powder suction nozzle; 138, powder baffle; 139, mounting block; 14, molding cylinder; 15, molding platform; 16, recycling box; 161, cleaning brush; 21, vibration motor; 22, first travel switch; 23, second travel switch. DETAILED DESCRIPTION

[0041] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0044] Aiming at the technical problem that a large amount of first material powder needs to be removed in the secondary laying process of powder in the background technology, and then the second material powder is laid, resulting in low powder utilization and low powder laying efficiency, the embodiment of the present invention provides a multi-material 3D printer, such as Figure 1 and 2 As shown, in one embodiment, the multi-material 3D printer includes a molding device, a powder-laying and suction device 13 and a control device (not shown), and the control device controls the operation of the powder-laying and suction device 13 and the molding device.

[0045] like Figure 1As shown, the molding device includes a molding chamber 10, a laser scanning head 11, a powder supply assembly 12, and a molding cylinder 14 and a molding platform 15 located in the molding chamber 10. The powder supply assembly 12 is connected to the powder supply port at the top of the molding chamber 10. The molding platform 15 is arranged in a liftable manner inside the molding cylinder 14. The laser scanning head 11 is located directly above the molding platform 15, receives instructions from the control device, and melts or sinters the powder on the molding platform 15 according to the graphic scanning data.

[0046] like Figure 2 As shown, the powder spreading and suction device 13 includes a powder spreading box 131, a scraper 132, a powder distribution component, a powder suction component and a translation component. The powder spreading box 131 is located above the molding cylinder 14 and can be reciprocated in a controllable manner along the X-axis direction of a horizontal plane; the translation component is arranged on the powder spreading box 131, and the translation component includes a linear guide 133 and a first driving source 134, the linear guide 133 is arranged along the Y-axis direction of the horizontal plane, and the linear guide 133 is provided with a slidable mounting block 139, and the first driving source 134 is used to drive the mounting block 139 to move; the powder distribution component and the powder suction component are arranged on the mounting block 139, the powder distribution component is used to receive the powder of the powder supply component 12 and discharge the powder, and the powder suction component is used to absorb the powder; the scraper 132 is fixed to the bottom of the powder spreading box 131 corresponding to the powder distribution component, and is used to scrape the powder on the molding platform 15 flat, and send the excess powder to the recycling box 16.

[0047] A first travel switch 22 is also provided at the end of one side of the linear guide rail. The first travel switch 22 is electrically connected to the control device. The first travel switch 22 can sense the in-position signal of the mounting block 139. During the 3D printing process, the control device uses the first travel switch 22 as the position zero point, combined with the first driving source 134, to achieve precise control of the position of the mounting block 139 on the linear guide rail 133.

[0048] During operation, the powder spreading and suction device 13 moves in the X-axis and Y-axis directions through the powder spreading box 131 and the translation component, respectively, to achieve accurate powder spreading in the specified area, greatly reducing the ineffective supply of powder during the printing process, and no large amount of powder needs to be provided to complete the printing. At the same time, regionalized powder spreading and suction greatly improves the working efficiency of the printer, and only one powder spreading and suction device 13 is required in the molding chamber 10, so that the overall volume of the printer is not too large and the structure is more compact.

[0049] Preferably, the first driving source 134 is a synchronous belt transmission driving assembly, and the synchronous belt transmission driving assembly realizes the transmission function by pulling the synchronous belt 1341 through the synchronous belt pulley by a stepping motor controlled by the control device. The mounting block 139 is fixed on the synchronous belt 1341 of the synchronous belt transmission driving assembly, and when the synchronous belt 1341 moves, it drives the powder distribution assembly and the powder suction assembly on the mounting block 139 to move along the Y-axis direction of the horizontal plane.

[0050] In one embodiment, if Figure 1 , 2 As shown in Figure 5, the powder dispensing assembly includes a powder dispensing nozzle 135, a second driving source 136 and a powder blocking plate 138. The powder dispensing nozzle 135 is mounted on a mounting block 139. A powder receiving port is provided at the top of the powder dispensing nozzle 135, and a powder dispensing port is provided at the bottom of the powder dispensing nozzle 135. The bottom of the powder dispensing nozzle 135 is located 0.3 mm to 1 mm above the top plane of the molding cylinder 14. The second driving source 136 is provided at the outside of the powder dispensing nozzle 135. The powder blocking plate 138 is provided in the inner cavity of the powder dispensing nozzle 135 and is connected to the output end of the second driving source 136. The rotation position of the powder blocking plate 138 is controlled by the control device. When the powder blocking plate 138 is in a fully closed state, the powder blocking plate 138 blocks the inner cavity channel of the powder dispensing nozzle 135. The upper part of the powder blocking plate 138 is used to temporarily hold the powder required for the printing. The control device controls the rotation of the powder blocking plate 138 to control when the powder falls onto the molding platform 15. In this embodiment, the top of the powder distributing nozzle 135 is in a funnel shape, which is more conducive to receiving powder below the powder supply port at the top of the molding chamber 10 and promoting the falling of powder.

[0051] Preferably, the second driving source 136 adopts a stepper motor controlled by a control device, and is combined with a second travel switch 23 and an induction iron (not shown) to realize the rotation position control of the powder blocking plate 138. The second travel switch 23 is installed on the outer side of the stepper motor shaft coaxially, and the stepper motor shaft is equipped with an induction iron. The second travel switch 23 can sense the rotation position signal of the induction iron, thereby realizing the rotation position control of the powder blocking plate 138.

[0052] Preferably, Figure 2 , 3 As shown, in this embodiment, in order to facilitate the disassembly and assembly of the powder blocking plate 138, the powder dispensing nozzle 135 is designed to be composed of an upper part and a lower part, which are connected into one by screws.

[0053] Preferably, a vibration motor 21 is also provided on the outer side of the top of the powder dispensing nozzle 135. The vibration motors 21 are distributed on both sides of the top of the powder dispensing nozzle 135. During the powder supply process, the two vibration motors 21 maintain a vibration state, and the powder remaining on the top of the powder dispensing nozzle 135 is shaken off to avoid mixing of different materials when laying heterogeneous materials next time.

[0054] In one embodiment, if Figure 2 and 3As shown, the powder suction assembly includes a powder suction nozzle 137, which is installed on a mounting block 139, and the bottom of the powder suction nozzle 137 is located 0.3 mm to 1 mm above the top plane of the molding cylinder 14, and the powder distribution nozzle 135 and the powder suction nozzle 137 are arranged on opposite sides of the mounting block 139, and the powder suction nozzle 137 is located in front of the powder spreading box 131 along the X-axis direction, and the top of the powder suction nozzle 137 is connected to the outside of the molding chamber 10 through a pipe, and is connected to an external recovery device.

[0055] The powder suction nozzle 137 is arranged in front of the powder spreading box body 131 to ensure that the powder suction nozzle 137 has a higher working efficiency.

[0056] In one embodiment, if Figure 1 and 4 As shown, the powder supply assembly 12 includes a plurality of powder supply funnels 121, a plurality of powder delivery branches 122 and a powder delivery main pipe 123. The plurality of powder supply funnels 121 are connected to one end of the plurality of powder delivery branches 122, and the other ends of the plurality of powder delivery branches 122 are connected to one end of the powder delivery main pipe 123. The other end of the powder delivery main pipe 123 is connected to the powder supply port at the top of the molding chamber 10. When a certain type of powder is needed, the corresponding powder supply funnel 121 is opened to deliver the powder into the molding chamber 10 through the powder delivery branches 122 and the powder delivery main pipe 123.

[0057] Preferably, a vibration motor 21 is also installed on the outside of the powder delivery main pipe 123. During the powder delivery process from the powder delivery main pipe 123, the vibration motor 21 keeps vibrating to prevent the powder from remaining on the powder delivery main pipe 123 and the powder delivery branch pipe 122, so as to avoid the mixing of different materials and powder contamination when laying heterogeneous materials next time.

[0058] In one embodiment, if Figure 7 As shown, a cleaning brush 161 is also installed on the wall of the molding chamber 10 on the right side of the molding platform 15, and the cleaning brush 161 is located at the end position of the moving path of the scraper 132. When the scraper 132 sends excess powder to the recovery box 16, the cleaning brush 161 and the bottom of the scraper 132 rub against each other, and the cleaning brush 161 cleans the powder particles remaining at the bottom of the scraper 132 to prevent powder contamination caused by multiple powder particles on the scraper 132.

[0059] The present invention also provides a printing method of a multi-material 3D printer, comprising the following steps:

[0060] S10: Assume that each layer of a multi-material part contains at least one material region, such as Fig. 9 As shown, if there are multiple material areas, the material composition of each material area is different; it is assumed that the 3D printing process of the multi-material part is controlled and operated by the control device; multiple powder materials are placed in different powder supply funnels 121;

[0061] S20: the molding platform 15 descends by a layer thickness;

[0062] S30: The control device determines the material type required by the current printing material area, such as Fig. 9 The material area A shown in the figure moves the powder distribution assembly of the powder-sucking device 13 to the position just below the powder supply port, and controls the powder material in the corresponding powder supply hopper to fall quantitatively into the powder distribution assembly;

[0063] S40: Figure 6 and 7 As shown, the powder distribution component moves to the top of the molding platform 15, and controls the translation component to move while advancing to the preset current material area, so that the powder flows down to the current material area of ​​the molding platform 15, and the scraper 132 spreads the powder to the molding platform 15, and the powder distribution component continues to translate to the top of the recycling box 16, and the excess powder will be dumped into the recycling box 16; the control device directs the laser beam through the laser scanning head 11 to selectively melt or sinter the powder material according to the scanning data of the current printing material area;

[0064] S50: Figure 8 As shown, the control device executes the residual powder cleaning procedure; the powder suction component starts to return above the recovery box 16, and when the powder suction component returns to the current molding area, the powder suction component is started, and the translation component is controlled to move, so that the powder suction component moves in the next printing material area and removes the residual powder in the area;

[0065] S60: Determine whether the current layer has been printed. If not, repeat steps S30 to S60. If it has been printed and the current layer is not the last layer, repeat steps S20 to S60 to complete the subsequent processing of the B material area or the C material area. If it has been printed and the current layer is the last layer, the printing of the multi-material part is completed.

[0066] Compared with the prior art, the multi-material 3D printer according to the embodiment of the present invention has the following beneficial effects:

[0067] 1. A multi-material 3D printer according to an embodiment of the present invention realizes precise powder spreading in a designated area by coordinating the movement of a powder spreading box and a translation assembly in the X-axis and Y-axis directions, thereby greatly reducing the ineffective supply of powder during the printing process and realizing additive manufacturing of heterogeneous materials of different layers and additive manufacturing of heterogeneous materials of the same layer.

[0068] 2. A multi-material 3D printer according to an embodiment of the present invention, by arranging a powder distribution nozzle and a powder suction nozzle on opposite sides of a mounting block, can accurately remove powder from a designated area, thereby realizing regionalized powder distribution and powder suction, greatly improving the working efficiency of the printer. At the same time, only one powder distribution and suction device is required in the molding chamber, reducing the overall volume of the printer and making the structure more compact.

[0069] 3. In a multi-material 3D printer according to an embodiment of the present invention, after each material area is formed, the excess powder outside the material area can be cleaned up, thereby preventing the mixing of the currently printed material with the next printing of heterogeneous materials.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A multi-material 3D printer, characterized in that: include: Forming device, powder laying and suction device and control device; The molding device comprises a molding chamber, a laser scanning head, a powder supply assembly, a molding cylinder body and a molding platform located in the molding chamber, the powder supply assembly is connected to a powder supply port at the top of the molding chamber, the laser scanning head is located directly above the molding platform, and the molding platform is escalably arranged inside the molding cylinder body; The powder spreading and suction device comprises a powder spreading box, a scraper, a powder spreading assembly, a powder suction assembly and a translation assembly; the powder spreading box is located above the top plane of the forming cylinder and can be controllably moved back and forth along the X-axis direction of the top plane of the forming cylinder; The translation assembly is arranged on the powder spreading box body, and the translation assembly includes a linear guide and a first driving source. The linear guide is arranged along the Y-axis direction of the top plane of the forming cylinder body, and the linear guide is provided with a slidable mounting block. The first driving source is used to drive the mounting block. A first travel switch is also provided at one end of one side of the linear guide. The first travel switch is electrically connected to the control device, and the first travel switch can sense the in-position signal of the mounting block; the first driving source is a synchronous belt transmission drive assembly, and the mounting block is fixed on the synchronous belt of the synchronous belt transmission drive assembly. The synchronous belt transmission drive assembly realizes the transmission function by pulling the synchronous belt through the synchronous belt pulley by a stepping motor controlled by the control device; the The powder distribution component is used to receive powder from the powder supply component and discharge powder, and includes a powder distribution nozzle, a second driving source and a powder baffle plate. The top of the powder distribution nozzle is provided with a powder receiving port, and the bottom is provided with a powder distribution port. The bottom of the powder distribution nozzle is located above the top plane of the forming cylinder body, and a vibration motor is provided on the outer side of the top of the powder distribution nozzle; the second driving source is provided on the outer side of the powder distribution nozzle; the powder baffle plate is provided in the inner cavity of the powder distribution nozzle and connected to the output end of the second driving source; the powder suction component is used to absorb powder; the powder distribution nozzle and the powder suction component are provided on the mounting block; the scraper is fixed to the bottom of the powder spreading box body corresponding to the powder distribution component, and a cleaning brush is also installed at the end position of the scraper moving path; The control device controls the operation of the powder laying and absorbing device and the forming device.

2. A multi-material 3D printer according to claim 1, characterized in that: The top of the powder dispensing nozzle is in a funnel shape.

3. A multi-material 3D printer according to claim 1, characterized in that: The powder suction assembly includes a powder suction nozzle, which is installed on the mounting block. The powder distribution nozzle and the powder suction nozzle are arranged on opposite sides of the mounting block. The powder suction nozzle is located in front of the powder spreading box body along the X-axis direction. The top of the powder suction nozzle is connected to the outside of the molding room through a pipe and connected to an external recovery device. The bottom of the powder suction nozzle is located above the top plane of the molding cylinder body.

4. A multi-material 3D printer according to claim 1, characterized in that: The powder supply assembly includes multiple powder supply funnels, multiple powder supply branch pipes and a powder supply main pipe. The multiple powder supply funnels are correspondingly connected to one end of the multiple powder supply branch pipes, the other ends of the multiple powder supply branch pipes are connected to one end of the powder supply main pipe, and the other end of the powder supply main pipe is connected to the powder supply port at the top of the molding chamber.

5. A multi-material 3D printer according to claim 4, characterized in that: A vibration motor is arranged outside the powder feeding main pipe.

6. A multi-material 3D printer according to claim 1, characterized in that: A cleaning brush is arranged on the wall plate of the molding chamber, and the cleaning brush is located at the end position of the moving path of the scraper.

7. A printing method of a multi-material 3D printer, using the 3D printer as claimed in any one of claims 1 to 6 for printing, characterized in that: The following steps are involved: S10: Assume that each layer of the multi-material part includes at least one material region. If there are multiple material regions, the material composition of each material region is different. Assume that the 3D printing process of the multi-material part is controlled by a control device. Place multiple powder materials in different powder supply funnels respectively. S20: The molding platform descends a layer thickness; S30: The control device moves the powder distribution component of the powder distribution and suction device to the bottom of the powder supply port according to the material type required by the current printing material area, and controls the powder material in the corresponding powder supply hopper to fall into the powder distribution component in a quantitative manner; S40: The powder distribution component moves to the top of the molding platform, and controls the translation component to move while advancing to the preset current material area, so that the powder flows down to the current material area of ​​the molding platform, and the scraper spreads the powder onto the molding platform. The powder distribution component continues to translate to the top of the recycling box, and the excess powder will be dumped into the recycling box; the control device directs the laser beam through the laser scanning head to selectively melt or sinter the powder material according to the scanning data of the current printing material area; S50: the control device executes the residual powder cleaning procedure; the powder suction component starts to return above the recycling box, and when the powder suction component returns to the current molding area, the powder suction component is started, and the translation component is controlled to move, so that the powder suction component moves in the next printing material area and removes the residual powder in the area; S60: Determine whether the current layer is printed. If not, repeat steps S30 to S60. If it is completed and the current layer is not the last layer, repeat steps S20 to S60. If it is completed and the current layer is the last layer, the printing of the multi-material part is completed.

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