Powder spreading system and powder spreading method for multi-material additive manufacturing

Abstract

The invention belongs to the related technical field of metal additive manufacturing, and discloses a powder spreading system for multi-material additive manufacturing, which comprises a powder feeding device, a powder storage cabin and a powder spreading device, the powder feeding device comprises a powder feeding gas circuit, a powder supply port and a rotary powder changing arm, the powder supply port is used for adding printing powder, the first end of the rotary powder changing arm is rotatably connected to the powder feeding gas circuit and communicates with the powder feeding gas circuit, and the powder feeding port is formed in the second end of the rotary powder changing arm; the inner space of the powder storage bin is divided into a plurality of independent sub-bins in the circumferential direction, the upper end of each sub-bin is provided with a powder inlet matched with the powder feeding port, the powder feeding port is connected with the different powder inlets through rotation so as to feed and store powder for the different sub-bins, and the lower end of each sub-bin is provided with a bin door. And opening and closing of the cabin doors control the printing powder in the corresponding sub-cabins to fall into the powder laying device, so that partitioned storage before processing of the printing powder with different components and flowing powder falling during processing are realized, the operation process of workers is simplified, and the applicability of powder laying type additive manufacturing in a multi-material application scene is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field related to metal additive manufacturing, and more specifically, relates to a powder spreading system and a powder spreading method for multi-material additive manufacturing. Background Art

[0002] Metal additive manufacturing technology is an important branch of additive manufacturing. The basic principle of additive manufacturing is to first use a computer to design a three-dimensional model of the part, then slice and layer the three-dimensional model through special software to obtain the contour data of the cross section, and then import it into the rapid prototyping equipment. The equipment controls the laser beam to selectively melt the metal powder of each layer according to the contour data, and gradually stack it into a three-dimensional metal part. Compared with other traditional precision machining technologies, the advantage of the technology is that it can directly manufacture metal parts with high precision, complex geometric structure, dense organization and good mechanical properties. The advantage of metal additive manufacturing technology is that it can directly manufacture metal parts with high precision, light weight, complex geometric structure, dense organization and good mechanical properties.

[0003] At present, metal additive manufacturing technology can be divided into two types according to the feeding method of metal powder: powder feeding type and powder spreading type. Although the powder feeding type has a faster forming speed, it is far inferior to the powder spreading type in terms of the accuracy of the parts obtained. Therefore, powder spreading metal additive manufacturing has great advantages in the preparation of high-precision complex precision parts. For example, laser selective melting technology has been well applied in the fields of medicine and automobiles. However, when changing powder during the processing, the current powder spreading additive manufacturing equipment generally needs to print one powder and then replace it with another. There is a defect of cumbersome steps for changing powder during processing, which makes most powder spreading additive manufacturing parts made of a single powder material. With the increase in application scenarios and the improvement of performance requirements, traditional powder spreading additive manufacturing equipment is difficult to prepare diversified parts with different components.

[0004] Therefore, in order to improve the applicability of powder-spreading additive manufacturing in multi-material application scenarios, it is urgent to develop a new type of powder-spreading system for additive manufacturing to solve the problems that the existing powder-spreading system for multi-material additive manufacturing is difficult to replace powder during processing and the manual operation is cumbersome. Summary of the invention

[0005] In view of the problems of difficulty in replacing powder during processing and cumbersome manual operation in existing multi-material additive manufacturing powder spreading systems, the present invention provides a powder spreading system and a powder spreading method for multi-material additive manufacturing, the purpose of which is to achieve partitioned storage of printing powders of different compositions before processing and separate powder flow during processing by providing a rotatable powder changing arm and a controllable opening and closing door, thereby simplifying the operation process of the staff and improving the applicability of powder spreading additive manufacturing in multi-material application scenarios.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a powder spreading system for multi-material additive manufacturing is provided, which comprises, from top to bottom, a powder feeding device, a powder storage cabin and a powder spreading device; the powder feeding device comprises a powder feeding air path and a powder supply port and a rotating powder changing arm which are sequentially arranged on the powder feeding air path, the powder supply port is used to add printing powder, the first end of the rotating powder changing arm can be rotatably connected to the powder feeding air path and communicated with the powder feeding air path, the second end of the rotating powder changing arm is provided with a powder feeding port; the internal space of the powder storage cabin is divided into a plurality of independent compartments along the circumferential direction, the upper end of each compartment is provided with a powder inlet matching the powder feeding port, the powder feeding port is connected with different powder inlets by rotation to feed powder to different compartments for storage, and the lower end of each compartment is provided with a hatch, the opening and closing control of the hatch corresponds to the printing powder in the compartment falling to the powder spreading device for powder spreading printing.

[0007] Preferably, the powder storage cabin is a hollow inverted cone structure, and the powder spreading system also includes a powder falling air path, which passes through the central axis of the powder storage cabin. A partition is fixedly connected between the tube wall of the powder falling air path and the outer wall of the powder storage cabin, and the partition divides the internal space of the powder storage cabin into a plurality of independent sub-cabins. The opening and closing control of each cabin door corresponds to the connection and isolation between the sub-cabin and the powder falling air path.

[0008] Preferably, there is a gap between the bottom end of the tube wall of the powder falling gas path and the bottom end of the powder storage cabin, so that there is an opening between the powder falling gas path and the lower end of each of the sub-cabins, or the tube wall of the powder falling gas path is provided with openings at corresponding positions at the lower end of each of the sub-cabins;

[0009] The hatch is arranged between two adjacent partitions at the opening and can slide up and down along the outer wall of the powder falling gas path. The hatch has a first position located above and a second position located below the powder storage cabin. In the first position, the hatch is located above the opening, and the opening connects the sub-cabin with the powder falling gas path. In the second position, the hatch is located at the opening, so that the sub-cabin is separated from the powder falling gas path.

[0010] Preferably, the powder spreading system also includes a powder wholeing component, which includes a connecting section and a powder wholeing section, the upper end of the connecting section is connected to the powder storage cabin and the connecting section is connected to the powder falling air path, the lower end of the connecting section is connected to the powder wholeing section, the powder wholeing section is a flat hollow structure, and a plurality of small holes are evenly distributed on the bottom surface; the connecting section is provided with a powder flow meter and a pressure limiting valve with adjustable opening.

[0011] Preferably, the powder spreading device includes a scraper and a forming substrate, the forming substrate is located directly below the powder whole assembly, the scraper is arranged above the forming substrate and can slide in the horizontal direction, and the scraper is used to spread the printing powder that falls from the small hole onto the forming substrate.

[0012] Preferably, the rotary powder changing arm further comprises a main section and a telescopic section, both of which are tubular structures, the inner diameter of the main section is larger than the outer diameter of the telescopic section, the main section faces the powder inlet and is fixedly connected to the second end of the rotary powder changing arm, the telescopic section is coaxially arranged with the main section, the telescopic section can be slid up and down and connected to the main section, the lower end of the telescopic section forms the powder delivery port, and the up and down sliding of the telescopic section drives the powder delivery port to rise and fall.

[0013] Preferably, a raised portion is provided on the upper end surface of each of the compartments, the powder inlet is provided on the raised portion, a sealing cover is provided on the periphery of the powder delivery port, the sealing cover matches the shape of the raised portion, and when the powder delivery port is in a position connected to any of the powder inlets, the sealing cover is sealed and connected to the corresponding raised portion.

[0014] Preferably, each of the compartments is provided with a spiral stirring rod inside, the spiral stirring rod comprises a rotating shaft and a spiral sheet obliquely surrounding the rotating shaft, the rotating shaft is fixedly connected to the spiral sheet, the spiral stirring rod is connected to an external motor, and the external motor controls the spiral stirring rod to rotate around the rotating shaft;

[0015] And / or, the inner wall of each of the compartments is provided with a heating plate.

[0016] According to another aspect of the present invention, a powder spreading method for multi-material additive manufacturing is provided, and the specific steps are as follows:

[0017] Step 1: Prepare various materials required for additive manufacturing and form various printing powders;

[0018] Step 2: Adding the first printing powder into the powder supply port;

[0019] Step 3: Control the rotation angle of the rotary powder exchange arm to above one of the powder inlets, introduce inert gas into the powder feeding gas path, and adjust the gas pressure so that the first type of printing powder flows into the corresponding compartment through the powder feeding gas path, the rotary powder exchange arm, the powder feeding port, and the powder inlet;

[0020] Step 4: When the storage amount of the first printing powder reaches a preset requirement, stop introducing the inert gas;

[0021] Step 5: Repeat the operations of steps 2 to 4 in sequence until each type of printing powder is stored in its respective compartment;

[0022] Step 6: According to the printing powder required for each layer of the additive manufacturing process, the hatch of the compartment storing the corresponding printing powder is controlled to open, so that the printing powder falls to the powder spreading device;

[0023] Step 7: After the printing powder required for each layer flows out of the hatch, close the corresponding hatch.

[0024] Preferably, the types of materials in the multiple different printing powders are the same, the ratios of the different materials vary in a gradient, and the multiple printing powders are printed in sequence to form gradient material additive manufacturing.

[0025] In general, the above technical solutions conceived by the present invention have the following technical effects compared with the prior art:

[0026] 1. Provide a powder spreading system for multi-material additive manufacturing, which can add printing powder of different components to each compartment before printing by arranging the internal space of the powder storage compartment to be divided into a plurality of mutually independent compartments along the circumferential direction, and by rotating a rotating powder changing arm connected to the powder inlet of each compartment at different angles, and by arranging a respective door for each compartment, the door of the corresponding compartment can be opened as needed during the printing process, thereby realizing the partitioned storage of printing powder of different components before processing and the divided flow of powder during processing, simplifying the operation process of the staff, and improving the applicability of powder spreading additive manufacturing in multi-material application scenarios;

[0027] 2. The present invention sets the powder storage cabin as a hollow inverted cone structure, so that the printing powder in the cabin is easier to move downward under the action of gravity, and sets a powder falling air path through the central axis of the powder storage cabin, so that when the cabin door is opened, the printing powder in the corresponding cabin enters the powder falling air path under the action of gravity and the turbulence of the powder falling air path, which is conducive to evenly dispersing the printing powder;

[0028] 3. The present invention further provides a powder sorting component, by connecting the connecting section of the powder sorting component with the powder dropping gas path, and providing a powder flow meter and a pressure-limiting valve with adjustable opening in the connecting section, so as to control the amount of printing powder falling into the powder spreading device; by setting the powder sorting section as a flat hollow structure with a plurality of small holes evenly distributed on the bottom surface, the printing powder enters the powder sorting component through the powder dropping gas path and is further dispersed evenly, which is conducive to improving the uniformity and flatness of the printing powder falling into the powder spreading device, thereby improving the printing quality;

[0029] 4. The present invention designs the raised portion at the upper end of the compartment and the sealing cover around the powder delivery port, so that when the powder delivery port is connected with any powder inlet, the raised portion and the sealing cover are sealed to avoid loss or contamination of printing powder when entering the compartment;

[0030] 5. The present invention provides a spiral stirring rod inside the compartment, and an external motor is provided to control the spiral stirring rod to rotate around the rotating shaft, so that the spiral blades obliquely surrounding the outside of the rotating shaft stir the printing powder in the compartment, thereby preventing the printing powder from sticking or agglomerating and causing the fluidity to decrease. A heating plate is provided on the inner wall of the compartment to heat the printing powder to keep it dry, so as to further improve the fluidity and enhance the printing quality.

[0031] 6. The present invention provides a powder spreading method for multi-material additive manufacturing. The method can pre-prepare a variety of different printing powders of the same material type and with gradient ratios of each material, store the multiple printing powders in partitions, and separate the powders for powder drop, and then perform powder spreading and printing in sequence to achieve gradient material additive manufacturing. The method has a wide range of application scenarios in the field of gradient material preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is an overall schematic diagram of a powder laying system for multi-material additive manufacturing provided by an embodiment of the present invention;

[0033] Figure 2 It is a structural schematic diagram of a powder storage cabin provided by an embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of the structure of the powder dropping gas path and the cabin door provided in an embodiment of the present invention;

[0035] Figure 4 is a schematic structural diagram of a spiral stirring rod provided in an embodiment of the present invention;

[0036] Figure 5 A schematic structural diagram of a rotary powder changing arm provided in an embodiment of the present invention;

[0037] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0038] 1-powder storage cabin, 2-rotating powder changing arm, 3-powder dropping gas path, 4-powder finishing section, 5-scraper, 6-forming substrate, 7-powder supply port, 8-powder delivery gas path, 9-sealing cover, 10-first high-pressure gas cylinder, 11-connecting section, 12-second high-pressure gas cylinder, 13-first gas path valve, 14-second gas path valve, 15-cavity, 16-pressure limiting valve, 17-powder inlet, 18-spiral stirring rod, 19-compartment, 20-protrusion, 21-cabin door, 181-rotating shaft, 182-spiral sheet, 201-main section, 202-first telescopic section, 203-second telescopic section, 204-third telescopic section. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The technical solution of the present invention is described in detail below with specific embodiments.

[0041] See also Figure 1 The present embodiment provides a powder spreading system for multi-material additive manufacturing, which includes a powder feeding device, a powder storage cabin 1 and a powder spreading device from top to bottom. The powder feeding device includes a powder feeding air path 8 and a powder supply port 7 and a rotary powder exchange arm 2 which are sequentially arranged on the powder feeding air path 8. The powder supply port 7 is used to add printing powder. The first end of the rotary powder exchange arm 2 can be circumferentially rotatably connected to the powder feeding air path 8 and communicated with the powder feeding air path 8. The second end of the rotary powder exchange arm 2 is provided with a powder feeding port. The internal space of the powder storage cabin 1 is circumferentially divided into a plurality of mutually independent compartments 19, such as Figure 2 As shown, a powder inlet 17 matching the powder delivery port is provided at the upper end of each of the compartments 19, and the powder delivery port is connected with different powder inlets 17 by rotating the powder changing arm 2 around the first end to deliver powder to different compartments 19 for storage, and a hatch 21 is provided at the lower end of each of the compartments 19, and the opening and closing control of the hatch 21 causes the printing powder in the corresponding compartment 19 to fall to the powder spreading device for powder spreading printing.

[0042] Specifically, each compartment 19 is provided with a pressure-stabilizing hole at the upper end, and the pressure-stabilizing hole is covered by a mesh surface or a film, so that gas can flow through the pressure-stabilizing hole and restrict the solid powder from passing through, thereby balancing the pressure in each compartment 19 while preventing the printing powder from leaking out. The powder supply port 7 is provided with a sealing cover above and a cavity 15 connected to the powder delivery gas path 8 below. The pre-prepared printing powder is added to the powder supply port 7 and temporarily stored in the cavity 15. When the inert gas is introduced, the printing powder in the cavity 15 is driven to enter the powder delivery gas path 8; the powder delivery gas path 8 can also be directly set as an opening on the powder delivery gas path 8, or other structures that match the device for adding printing powder, which are not limited here. The front end of the powder delivery gas path 8 is connected to the first high-pressure gas cylinder 10, and the first high-pressure gas cylinder 10 is provided with a first gas path valve 13. By controlling the opening and closing of the first gas path valve 13, the first high-pressure gas cylinder 10 is controlled to provide high-pressure inert gas to transport printing powder; the powder delivery gas path 8 can also be directly connected to other structures that can provide a high-pressure gas source, which are not limited here. The inert gas used is argon, and other inert gases may also be used, which is not limited here.

[0043] In the zoning powder storage link before printing, the pre-prepared printing powder is added to the powder feeding air path 8 through the powder supply port 7. After adding enough printing powder of the same type, the powder supply port 7 is sealed, and the rotating powder exchange arm 2 is controlled to rotate so that the powder feeding port is connected to the powder inlet 17 of the compartment 19 storing the printing powder. At this time, high-pressure inert gas is introduced into the powder feeding air path 8, so that the printing powder in the powder feeding air path 8 passes through the rotating powder exchange arm 2 under the action of gas pressure and falls into the corresponding compartment 19. According to the number of types of printing powders with different components required for additive manufacturing, the above process is repeated until each printing powder is stored in a sufficient amount in different compartments 19, thereby realizing the zoning storage of printing powders with different components before processing.

[0044] Specifically, the powder storage cabin 1 is a hollow inverted cone structure, so that the printed powder in the compartment 19 can move downward more easily under the action of gravity. The powder spreading system also includes a powder falling gas path 3, which passes through the central axis of the powder storage cabin 1. Eight evenly distributed partitions are fixedly connected between the tube wall of the powder falling gas path 3 and the outer wall of the powder storage cabin 1. The partition divides the internal space of the powder storage cabin 1 into eight independent compartments 19. The opening and closing control of each of the hatches 21 corresponds to the connection and separation between the compartment 19 and the powder falling gas path 3. The front end of the powder falling gas path 3 is connected to the second high-pressure gas cylinder 12, and the second high-pressure gas cylinder 12 is provided with a second gas path valve 14. By controlling the opening and closing of the second gas path valve 14, the second high-pressure gas cylinder 12 is controlled to provide high-pressure inert gas to the powder falling gas path 3; the powder delivery gas path 8 can also be directly connected to other structures that can provide a high-pressure gas source, which is not limited here. The inert gas uses argon gas, and other inert gases can also be used, which is not limited here.

[0045] In the powder dropping stage, the hatch 21 of the corresponding compartment 19 is opened according to the printing powder required during processing, and high-pressure inert gas is introduced into the powder dropping gas path 3, so that the printing powder in the corresponding compartment 19 enters the powder dropping gas path 3 under the action of gravity and the turbulence of the powder dropping gas path 3, which is conducive to evenly dispersing the printing powder.

[0046] Specifically, Figure 3As shown, there is a gap between the bottom end of the tube wall of the powder falling gas path 3 and the bottom end of the powder storage cabin 1, so that there is an opening between the powder falling gas path 3 and the lower end of each of the sub-cabins 19, or the tube wall of the powder falling gas path 3 is provided with openings at the corresponding positions of the lower ends of each of the sub-cabins 19; the hatch 21 is arranged between two adjacent partitions at the opening and can slide up and down along the outer wall of the powder falling gas path 3, and the hatch 21 has a first position located at the top and a second position located at the bottom relative to the powder storage cabin 1, in the first position, the hatch 21 is located above the opening, and the opening makes the sub-cabin 19 communicate with the powder falling gas path 3, and in the second position, the hatch 21 is located at the opening so that the sub-cabin 19 is separated from the powder falling gas path 3. The opening and closing of the hatch 21 is controlled by setting a pneumatic transmission structure or by electric remote control, which is not limited here.

[0047] As a further preferred embodiment, the powder spreading system also includes a powder wholeing component, which includes a connecting section 11 and a powder wholeing section 4. The upper end of the connecting section 11 is connected to the powder storage cabin 1 and the connecting section 11 is connected to the powder falling air path 3. The connecting section 11 is provided with a powder flow meter and a pressure limiting valve 16 with an adjustable opening. The opening of the pressure limiting valve 16 is adjusted according to the powder flow meter to control the flow rate of the printed powder falling into the powder spreading device. After the powder has finished falling, the pressure limiting valve 16 is closed to stop the air supply to the powder falling air path 3 to prevent the powder from flying to the area outside the powder spreading device and causing blockage; the lower end of the connecting section 11 is connected to the powder wholeing section 4. The powder wholeing section 4 is a flat hollow structure with a plurality of small holes evenly distributed on the bottom surface, so that the printed powder enters the powder wholeing component through the powder falling air path 3 and is further dispersed evenly, which is beneficial to improve the uniformity and flatness of the printed powder falling into the powder spreading device, thereby improving the printing quality.

[0048] Specifically, the powder spreading device includes a scraper 5 and a forming substrate 6, wherein the forming substrate 6 is located directly below the powder whole assembly, and the scraper 5 is disposed above the forming substrate 6 and can slide in a horizontal direction, and the scraper 5 is used to spread the printing powder that falls from the small hole onto the forming substrate 6.

[0049] As a further preferred embodiment, Figure 5As shown, the rotary powder exchange arm 2 also includes a main section 201 and a telescopic section. Both the main section 201 and the telescopic section are tubular structures. The main section 201 faces the powder inlet 17 and is fixedly connected to the second end of the rotary powder exchange arm 2. The telescopic section is coaxially arranged with the main section 201. The inner diameter of the main section 201 is larger than the outer diameter of the telescopic section. The lower end of the telescopic section forms the powder delivery port. The telescopic section can be slid up and down and connected to the main section 201, including a retracted state of sliding upward into the main section 201 and an extended state of sliding downward. The telescopic section is in a retracted state (such as when the rotary powder exchange arm 2 rotates) when the rotary powder exchange arm 2 rotates. Figure 5 b, c in the figure), when the powder delivery port and the powder drop port are connected, the powder delivery port is in the extended state (as shown in Figure 5 As shown in a and b in the figure), the position interference between the rotating powder changing arm 2 and the powder storage chamber 1 is avoided, and at the same time, it is beneficial to the connection between the powder delivery port and the powder drop port.

[0050] Specifically, the telescopic joint can be designed to be multi-layered, such as including a first telescopic joint 202, a second telescopic joint 203 and a third telescopic joint 204, the inner diameter of the main section 201 is larger than the outer diameter of the first telescopic joint 202, the inner diameter of the first telescopic joint 202 is larger than the outer diameter of the second telescopic joint 203, the inner diameter of the second telescopic joint 203 is larger than the outer diameter of the third telescopic joint 204, and the lower end of the third telescopic joint 204 forms the powder delivery port.

[0051] Specifically, a protrusion 20 is provided on the upper end surface of each of the compartments 19, the powder inlet 17 is provided on the protrusion 20, and a sealing cover 9 is provided on the periphery of the powder delivery port, the sealing cover 9 matches the shape of the protrusion 20, and when the powder delivery port is in a position connected to any of the powder inlets 17, the sealing cover 9 is sealed and connected to the corresponding protrusion 20 to avoid loss or contamination of printing powder when entering the compartment 19.

[0052] As a further preferred embodiment, Figure 4 As shown, each of the compartments 19 is provided with a spiral stirring rod 18, and the spiral stirring rod 18 includes a rotating shaft 181 and a spiral blade 182 obliquely surrounding the outside of the rotating shaft 181, the rotating shaft 181 is fixedly connected to the spiral blade 182, and the spiral stirring rod 18 is connected to an external motor, and the external motor controls the spiral stirring rod 18 to rotate around the rotating shaft 181, so that the spiral blade 182 stirs the printing powder in each compartment 19 to prevent the printing powder from sticking or clumping and causing a decrease in fluidity; and / or, the inner wall of each compartment 19 is provided with a heating plate to heat the printing powder to keep it dry so as to further improve the fluidity and enhance the printing quality.

[0053] According to another aspect of the present invention, a powder spreading method for multi-material additive manufacturing is provided, and the specific steps are as follows:

[0054] Step 1: Prepare various materials required for additive manufacturing and form various printing powders;

[0055] Step 2: Add the first printing powder into the powder supply port 7;

[0056] Step 3: Control the rotation angle of the rotary powder exchange arm 2 to above one of the powder inlets 17, introduce inert gas into the powder delivery gas path 8, and adjust the gas pressure so that the first type of printing powder flows into the corresponding compartment 19 through the powder delivery gas path 8, the rotary powder exchange arm 2, the powder delivery port and the powder inlet 17;

[0057] Step 4: When the storage amount of the first printing powder reaches a preset requirement, stop introducing the inert gas;

[0058] Step 5: Repeat the operations of steps 2 to 4 in sequence until each type of printing powder is stored in its respective compartment 19;

[0059] Step 6: According to the printing powder required for each layer of the additive manufacturing process, the hatch 21 of the compartment 19 storing the corresponding printing powder is controlled to open, so that the printing powder falls to the powder spreading device;

[0060] Step 7: After the printing powder required for each layer flows out from the hatch 21, close the corresponding hatch 21.

[0061] Preferably, the types of materials in the multiple different printing powders are the same, the ratios of the different materials vary in a gradient, and the multiple printing powders are printed in sequence to form gradient material additive manufacturing.

[0062] Based on this, the powder laying system and powder laying method for multi-material additive manufacturing are further described by taking Ti6Al4V-AlMgScZr composition gradient material additive manufacturing as an example. This example includes the following steps:

[0063] S1: 8 kinds of metal spherical powders for 3D printing with a particle size of 25-53 μm of different compositions required for printing are prepared in advance, and the mass fractions are 100% Ti6Al4V, 90% Ti6Al4V+10% AlMgScZr, 80% Ti6Al4V+20% AlMgScZr, 60% Ti6Al4V+40% AlMgScZr, 40% Ti6Al4V+60% AlMgScZr, 20% Ti6Al4V+80% AlMgScZr, 90% Ti6Al4V+10% AlMgScZr, and 100% AlMgScZr respectively;

[0064] S2: Add printing powder with a mass fraction of 100% Ti6Al4V into the powder supply port 7, open the first high-pressure gas cylinder 10 connected to the powder delivery gas path 8, adjust the gas pressure through the first gas path valve 13, and wait for the printing powder to flow to the rotating powder exchange arm 2;

[0065] S3: The rotary powder changing arm 2 is rotated to align with the first compartment 19 in the projection direction, and the telescopic section is extended downward to seal the sealing cover 9 and the raised portion 20 (such as Figure 5 As shown in a), the printing powder is stored in the first compartment 19, the heating plate and the rotating stirring rod in the first compartment 19 are turned on, and the first gas path valve 13 is closed to stop the gas supply of the powder delivery gas path 8;

[0066] S4: The connection port of the first compartment 19 is closed, and the telescopic joint is retracted upward (such as Figure 5 b), add 90% Ti6Al4V+10% AlMgScZr printing powder to the powder supply port 7, open the first high-pressure gas cylinder 10 connected to the powder delivery gas path 8, adjust the gas pressure through the first gas path valve 13, and wait for the printing powder to flow to the rotating powder exchange arm 2 (as shown in FIG. Figure 5 (as shown in c in the figure);

[0067] S5: Make the rotating powder changing arm 2 clockwise reach the top of the second to eighth compartments 19 in turn, and repeat steps S2 to S4 for printing powders of different mass fractions until all eight component powders are stored in their respective compartments 19;

[0068] S6: Open the hatch 21 corresponding to the first compartment 19, open the second high-pressure gas cylinder 12 connected to the powder dropping gas path 3, adjust the gas pressure through the second gas path valve 14, and control the flow through the pressure limiting valve 16, so that the printing powder with a mass fraction of 100% Ti6Al4V enters the powder assembly and is fully dispersed and evenly falls onto the forming substrate 6, thereby forming a layer of printing powder with a mass fraction of 100% Ti6Al4V on the forming substrate 6;

[0069] S7: Printing the layer of printing powder;

[0070] S8: Repeat the process of S7 to S8 to print the printing powder with a mass fraction of 100% Ti6Al4V layer by layer;

[0071] S9: Open the corresponding doors 21 of the second to eighth compartments 19 in sequence, and repeat the operations S7 to S9 until the printing of 8 kinds of printing powders by mass fractions is completed to obtain Ti6Al4V-AlMgScZr composition gradient parts.

[0072] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A powder spreading system for multi-material additive manufacturing, characterized in that: The invention comprises, from top to bottom, a powder feeding device, a powder storage chamber (1) and a powder spreading device; the powder feeding device comprises a powder feeding air path (8) and a powder supply port (7) and a rotary powder exchange arm (2) which are arranged on the powder feeding air path (8) in sequence, the powder supply port (7) being used for adding printing powder, the first end of the rotary powder exchange arm (2) being rotatably connected to the powder feeding air path (8) and communicating with the powder feeding air path (8), the second end of the rotary powder exchange arm (2) being provided with a powder feeding port; the interior of the powder storage chamber (1) The space is divided into a plurality of mutually independent compartments (19) along the circumferential direction, and a powder inlet (17) matching the powder delivery port is provided at the upper end of each compartment (19), and the powder delivery port is connected with different powder inlets (17) by rotation so as to deliver powder to and store powder in different compartments (19), and a door (21) is provided at the lower end of each compartment (19), and the opening and closing control of the door (21) causes the printing powder in the corresponding compartment (19) to fall to the powder spreading device for powder spreading printing.

2. The powder spreading system for multi-material additive manufacturing according to claim 1, characterized in that: The powder storage chamber (1) is a hollow inverted cone structure, and the powder spreading system also includes a powder falling air path (3), the powder falling air path (3) passes through the central axis of the powder storage chamber (1), and a partition is fixedly connected between the tube wall of the powder falling air path (3) and the outer wall of the powder storage chamber (1), and the partition divides the internal space of the powder storage chamber (1) into a plurality of mutually independent sub-cabins (19), and the opening and closing control of each of the cabin doors (21) corresponds to the connection and isolation between the sub-cabin (19) and the powder falling air path (3).

3. The powder spreading system for multi-material additive manufacturing according to claim 2, characterized in that: There is a distance between the bottom end of the tube wall of the powder falling gas path (3) and the bottom end of the powder storage cabin (1), so that there is an opening between the powder falling gas path (3) and the lower end of each of the compartments (19), or the tube wall of the powder falling gas path (3) is provided with an opening at a corresponding position at the lower end of each of the compartments (19); The door (21) is arranged between two adjacent partitions at the opening and can slide up and down along the outer wall of the powder falling gas path (3). The door (21) has a first position located above and a second position located below the powder storage cabin (1). In the first position, the door (21) is located above the opening, and the opening enables the sub-cabin (19) to be connected to the powder falling gas path (3). In the second position, the door (21) is located at the opening, so that the sub-cabin (19) is separated from the powder falling gas path (3).

4. The powder spreading system for multi-material additive manufacturing according to claim 1, characterized in that: The powder spreading system further comprises a powder finishing component, the powder finishing component comprising a connecting section (11) and a powder finishing section (4), the upper end of the connecting section (11) being connected to the powder storage chamber (1) and the connecting section (11) being in communication with the powder falling air path (3), the lower end of the connecting section (11) being connected to the powder finishing section (4), the powder finishing section (4) being a flat hollow structure with a plurality of small holes evenly distributed on the bottom surface; the connecting section (11) being provided with a powder flow meter and a pressure limiting valve (16) with an adjustable opening.

5. The powder spreading system for multi-material additive manufacturing according to any one of claims 1 to 4, characterized in that: The powder spreading device comprises a scraper (5) and a forming substrate (6), wherein the forming substrate (6) is located directly below the powder leveling component, and the scraper (5) is arranged above the forming substrate (6) and can slide in a horizontal direction, and the scraper (5) is used to spread the printing powder that falls from the small hole onto the forming substrate (6).

6. The powder spreading system for multi-material additive manufacturing according to any one of claims 1 to 4, characterized in that: The rotary powder exchange arm (2) further comprises a main section (201) and a telescopic section, wherein the main section (201) and the telescopic section are both tubular structures, the inner diameter of the main section (201) is larger than the outer diameter of the telescopic section, the main section (201) faces the powder inlet (17) and is fixedly connected to the second end of the rotary powder exchange arm (2), the telescopic section is coaxially arranged with the main section (201), the telescopic section can be slid up and down and connected to the main section (201), the lower end of the telescopic section forms the powder delivery port, and the upward and downward sliding of the telescopic section drives the powder delivery port to rise and fall.

7. The powder spreading system for multi-material additive manufacturing according to claim 6, characterized in that: A protrusion (20) is provided on the upper end surface of each compartment (19), the powder inlet (17) is provided on the protrusion (20), a sealing cover (9) is provided on the periphery of the powder delivery port, the sealing cover (9) matches the shape of the protrusion (20), and when the powder delivery port is in a position connected with any of the powder inlets (17), the sealing cover (9) is sealed and connected with the corresponding protrusion (20).

8. The powder spreading system for multi-material additive manufacturing according to any one of claims 1 to 4, characterized in that: Each of the compartments (19) is provided with a spiral stirring rod (18) inside, the spiral stirring rod (18) comprising a rotating shaft (181) and a spiral blade (182) obliquely surrounding the rotating shaft (181), the rotating shaft (181) and the spiral blade (182) being fixedly connected, the spiral stirring rod (18) being connected to an external motor, and the external motor controlling the spiral stirring rod (18) to rotate around the rotating shaft (181); And / or, the inner wall of each compartment (19) is provided with a heating plate.

9. A powder spreading method for multi-material additive manufacturing, characterized in that: The powder laying system for multi-material additive manufacturing based on any one of claims 1 to 8, the specific steps are as follows: Step 1: Prepare various materials required for additive manufacturing and form various printing powders; Step 2: Adding the first printing powder into the powder supply port (7); Step 3: Control the rotation angle of the rotary powder exchange arm (2) to above one of the powder inlets (17), introduce inert gas into the powder delivery air path (8), and adjust the air pressure so that the first type of printing powder flows into the corresponding compartment (19) through the powder delivery air path (8), the rotary powder exchange arm (2), the powder delivery port and the powder inlet (17); Step 4: When the storage amount of the first printing powder reaches a preset requirement, stop introducing the inert gas; Step 5: Repeat the operations of step 2 to step 4 in sequence until each type of printing powder is stored in its own compartment (19); Step 6: According to the printing powder required for each layer in the additive manufacturing process, the hatch (21) of the compartment (19) storing the corresponding printing powder is controlled to open, so that the printing powder falls to the powder spreading device; Step 7: After the printing powder required for each layer flows out from the hatch (21), the corresponding hatch (21) is closed.

10. The powder spreading method for multi-material additive manufacturing according to claim 9, characterized in that: The types of materials in the various printing powders are the same, and the ratios of the different materials vary in a gradient. The various printing powders are printed in sequence to form gradient material additive manufacturing.

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