A multi-material laser powder bed fusion powder spreading device and additive manufacturing method

Abstract

The present application relates to the technical fields of metal additive manufacturing, in particular to a multi-material laser powder bed fusion powder laying device and additive manufacturing method, the device comprises a forming cabin, a first powder laying assembly and a second powder laying assembly, the first powder laying assembly comprises a powder supply cylinder and a first scraper, which is used for laying the first powder on the forming area; the second powder laying assembly comprises a powder suction tube, a powder feeding mechanism and a second scraper, the three are connected with the movement mechanism on the inner wall top surface of the forming cabin through a connecting plate, the movement mechanism drives the three to move in the horizontal direction as a whole, and sequentially completes the negative pressure suction of the un-melted first powder in the second powder melting area, the quantitative feeding of the second powder and the local flattening operation. Through the physical separation of the first scraper and the second scraper, the cross contamination problem of heterogeneous powder is eliminated from the root, and the forming quality and process stability of multi-material composite parts are ensured.

Description

Technical Field

[0001] This invention relates to the field of metal additive manufacturing technology, and in particular to a multi-material laser powder bed melting and powder spreading device and an additive manufacturing method. Background Technology

[0002] With the rapid development of metal additive manufacturing technology, laser powder bed fusion molding has been widely applied in key manufacturing fields such as aerospace, high-end equipment, and medical devices due to its outstanding advantages such as high forming accuracy, good component density, and excellent mechanical properties. As industrial equipment continues to iterate and upgrade towards lightweight, integrated, and multifunctional directions, single-material components are no longer suitable for complex and extreme service conditions. Multi-material integrated forming technology is gradually becoming the core development direction of the industry. Among them, achieving stable, clean, and interference-free partitioning of dissimilar metal powders is the core prerequisite for ensuring the quality and process stability of multi-material laser powder bed fusion molding.

[0003] Currently, most existing laser powder bed fusion molding equipment adopts a traditional single-scraper integrated powder spreading structure. This structure uses a single fixed scraper to reciprocate and complete the conveying, leveling, and full-coverage spreading of the entire powder layer. While this structure is simple and mature, and can meet the stable forming requirements of a single metal powder, it has significant technical drawbacks in multi-material zoned composite forming conditions. During multi-material alternating powder spreading operations, different types of metal powders share the same scraper, spreading stroke, and powder storage structure. The scraper surface, scraper gaps, and spreading path are highly susceptible to residues of previously mixed powders, leading to cross-contamination and severe problems. This results in substandard mechanical properties of the parts, increased forming defects, and the scrapping of large quantities of high-purity metal powder, significantly increasing the production cost and material waste in multi-material additive manufacturing.

[0004] Current technologies for preventing contamination in multi-material laser powder bed fusion can be broadly categorized into two types: improved traditional single-scraper powder placement schemes and non-contact powder placement schemes. The first type, improved traditional single-scraper powder placement schemes, attempts to reduce powder mixing probability by adding isolation baffles, zoned powder hoppers, and blowing / suction structures. However, this approach still relies on a single scraper to complete the entire powder placement operation, with the scraper constantly contacting various dissimilar powders. This fails to eliminate the root causes of scraper adhesion and powder entrainment, leaving contamination risks unresolved and limiting the effectiveness of isolation and contamination prevention. The second type, non-contact powder placement schemes, primarily include ultrasonic vibration powder feeding, electrostatic adsorption powder placement, and micro-nozzle spray powder placement. This approach abandons the physical scraper contact leveling mode, relying instead on ultrasonic vibration powder delivery, electric field adsorption powder setting, and precise micro-nozzle spraying to complete powder placement. This effectively avoids powder residue and cross-contamination caused by mechanical contact. However, this type of technology generally suffers from defects such as poor uniformity of powder layer thickness, insufficient flatness of large-area powder spreading, easy agglomeration and clogging of fine powder, poor process stability, and low forming efficiency. It is only suitable for small-scale, low-precision test scenarios and cannot be adapted to industrial continuous forming production.

[0005] Therefore, how to effectively avoid cross-contamination of different powders during the multi-material powder bed melting process while ensuring process stability, improve the cleanliness and operational reliability of multi-material powder bed laying, and ensure the continuous and stable forming of multi-material components are the technical challenges that urgently need to be solved in the field of multi-material laser powder bed melting technology. Summary of the Invention

[0006] To alleviate the above-mentioned technical problems, the technical solution provided by the present invention is as follows: A multi-material laser powder bed melting and spreading device includes a laser system for selectively scanning and melting powder layers, comprising a forming chamber, a first powder spreading component, and a second powder spreading component; A forming cylinder is installed at the bottom of the forming chamber; The bottom surface of the inner wall of the forming chamber is provided with a forming area corresponding to the forming cylinder; The first powder spreading component includes a powder supply cylinder and a first scraper; The powder supply cylinder is located at the bottom of the forming chamber and is used to store the first powder; The first scraper is located inside the forming chamber and can move horizontally along the bottom surface of the inner wall; The second powder spreading component includes a powder suction tube, a powder feeding mechanism, and a second scraper; The powder suction pipe, powder feeding mechanism, and second scraper are connected to the motion mechanism located on the top surface of the inner wall of the forming chamber via a connecting plate; The motion mechanism can drive the powder suction tube, the powder feeding mechanism, and the second scraper to move horizontally; The powder feeding mechanism is used to store the second powder.

[0007] Furthermore, the powder suction pipe is connected to the negative pressure powder suction tank via a pipeline, and the negative pressure powder suction tank and the forming chamber are set up separately.

[0008] Furthermore, the powder feeding mechanism includes a powder feeding hopper and a screw valve fixed to the frame; The top of the frame is fixedly connected to the connecting plate; The powder feeding hopper is connected to the feed end of the screw valve; The screw inside the screw valve is connected to the motor drive. The motor is used to drive the screw to rotate so that the second powder in the powder feeding bin is discharged quantitatively from the discharge end of the screw valve.

[0009] Furthermore, the motor is a servo motor or a stepper motor, and the motor is connected to the screw drive of the screw valve through a reduction gearbox; the number of rotations or the rotation angle of the motor can be adjusted to regulate the single discharge amount of the screw valve.

[0010] Furthermore, the second scraper includes a fixed plate, a drive unit, and a scraper holder; The top of the fixing plate is fixedly connected to the connecting plate; The drive unit is fixed to one side of the fixed plate and connected to the scraper holder, on which the scraper holder is fitted with a blade head; The drive unit is used to drive the scraper holder and the cutter head to reciprocate in the vertical direction.

[0011] Furthermore, guide components are provided on both sides of the drive unit, and the guide components include guide rods and linear bearings; The linear bearing is mounted vertically on the fixed plate, and the guide rod passes through the linear bearing and can slide vertically. The bottom end of the guide rod is connected to the scraper holder, and the upper end of the guide rod is equipped with a limit ring to limit the lifting stroke of the cutter head.

[0012] Furthermore, the forming area includes a first powder melting zone and a second powder melting zone.

[0013] Furthermore, one or more sets of second powder spreading components are installed inside the forming chamber.

[0014] A multi-material laser powder bed fusion additive manufacturing method, employing the aforementioned powder spreading apparatus, includes the following steps: S1. Drive the first scraper to reciprocate linearly along the forming area to spread the first powder over the entire forming area to form the first powder layer; S2. Drive the laser system to selectively scan and melt the first powder layer in the first powder melting zone according to the preset scanning and melting path of the first powder; S3. Drive the second powder spreading component to move horizontally to the preset position, remove the unmelted first powder in the second powder melting zone, and spread the second powder in the second powder melting zone; S4. Drive the laser system to selectively scan and melt the second powder in the melting zone according to the preset scanning melting path of the second powder; S5. Drive the powder suction tube to move above the second powder melting zone and remove the unmelted second powder; S6. Drive the forming cylinder downwards by one layer thickness, return to step S1 to continue performing powder spreading and selective scanning melting, and cyclically stack layer by layer until the additive manufacturing of the multi-material composite part is completed.

[0015] Furthermore, Step S3 specifically includes: S31. The driving suction tube uses negative pressure to remove the unmelted first powder; S32. Drive the powder feeding mechanism to quantitatively feed the second powder into the second powder melting zone; S33. Drive the second scraper to move above the second powder melting zone and lower it to the preset powder spreading height; S34. Drive the second scraper to move horizontally and scrape the second powder placed in the second powder melting zone; S35. Drive the second scraper to lift, so that the second powder spreading component returns to standby state.

[0016] The beneficial effects of the multi-material laser powder bed melting and powder spreading device and additive manufacturing method in this invention are analyzed as follows: 1. This invention sets up two independent powder spreading systems, a first powder spreading component and a second powder spreading component. The first scraper only contacts the first powder and the second scraper only contacts the second powder. This completely eliminates the problems of powder sticking, entrainment and cross-contamination caused by dissimilar powders sharing the same scraper from the physical structure level, and ensures the cleanliness and forming quality of multi-material zoned powder spreading from the source.

[0017] 2. In this invention, the second powder spreading component integrates the powder suction pipe, the powder feeding mechanism, and the second scraper into one unit. The three components are driven to move horizontally as a whole by the motion mechanism, thereby completing the removal of residual powder, quantitative feeding of the second powder, and local leveling in sequence. The process is tightly connected and highly automated. The powder feeding mechanism uses a screw valve in conjunction with a servo motor or stepper motor to achieve quantitative discharge, ensuring the uniformity and consistency of the local powder spreading layer thickness.

[0018] 3. In this invention, the second scraper achieves vertical lifting and lowering of the blade head through a drive unit. In the non-operation state, the blade head is raised and detached from the powder layer to avoid interference with the formed surface. The powder suction pipe is connected to the negative pressure powder suction tank outside the forming chamber through a pipeline. The separate setting avoids the impact of vibration transmission on the powder spreading accuracy, and at the same time facilitates independent cleaning and maintenance without opening the forming chamber.

[0019] 4. In this invention, one or more sets of second powder spreading components can be set in the forming chamber, which has good scalability and can flexibly adapt to the composite forming requirements of two or more materials, and is suitable for the manufacturing of multi-material integrated components. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the structure of the multi-material laser powder bed melting and powder spreading device provided in the embodiments of the present invention; Figure 2 This is a schematic diagram of the powder feeding mechanism; Figure 3 This is a schematic diagram of the second scraper. Figure 4 A flowchart of a multi-material laser powder bed fusion additive manufacturing method provided for an embodiment of the present invention.

[0022] icon: 100 - Forming chamber; 110 - Forming cylinder; 120 - Forming area; 121 - First powder melting zone; 122 - Second powder melting zone; 200 - First powder spreading component; 210 - Powder supply cylinder; 220 - First scraper; 300-Second powder spreading assembly; 310-Powder suction pipe; 320-Powder feeding mechanism; 321-Frame; 322-Powder feeding hopper; 323-Screw valve; 324-Motor; 325-Discharge end; 330-Second scraper; 331-Fixing plate; 332-Drive unit; 333-Scraper holder; 334-Cut head; 335-Guide rod; 336-Linear bearing; 337-Limit ring; 340-Connecting plate; 350-Motion mechanism. Detailed Implementation

[0023] like Figures 1 to 4 As shown, this solution provides a multi-material laser powder bed melting and spreading device, including a laser system, a forming chamber 100, a first spreading component 200 and a second spreading component 300. The laser system is set in the forming chamber 100 and can selectively scan and melt the powder layer in the forming chamber 100 according to a preset scanning path. The laser system is an existing conventional component and is not separately labeled in the figure.

[0024] The bottom surface of the inner wall of the forming chamber 100 is provided with a forming area 120 corresponding to the forming cylinder 110. This forming area 120 is a working plane area on the bottom surface of the inner wall of the forming chamber 100 for powder laying and laser melting, including a first powder melting area 121 and a second powder melting area 122. The first powder melting area 121 is the area where the first powder is melted by laser scanning to form the first material part of the part, and the second powder melting area 122 is the area where the second powder is melted by laser scanning to form the second material part of the part. The division of the first powder melting area 121 and the second powder melting area 122 is determined according to the multi-material distribution design of the part, and the area ratio and relative position of the two can be set according to the structural requirements of the part. It should be noted that the division of the first powder melting area 121 and the second powder melting area 122 is a functional partition in the process concept. In terms of physical structure, the forming area 120 is a continuous plane, and there is no physical separation between the first powder melting area 121 and the second powder melting area 122.

[0025] A forming cylinder 110 is provided at the bottom of the forming chamber 100. The forming cylinder 110 is a cylinder that can be raised and lowered in the vertical direction. Its top surface serves as a reference surface for powder laying and part forming. The forming cylinder 110 is driven by a lifting drive mechanism and moves downward by one layer thickness distance after each forming cycle.

[0026] The first powder spreading assembly 200 includes a powder supply cylinder 210 and a first scraper 220. The powder supply cylinder 210 is disposed at the bottom of the forming chamber 100 and is used to store the first powder. The powder supply cylinder 210 is disposed adjacent to the forming cylinder 110. The top surface of the powder supply cylinder 210 is flush with the bottom surface of the inner wall of the forming chamber 100 so that the first scraper 220 can scrape the first powder from the opening of the powder supply cylinder 210 to the forming area 120. The first scraper 220 is disposed in the forming chamber 100 and can move horizontally along the bottom surface of the inner wall. Specifically, the first scraper 220 can make reciprocating linear motion in the horizontal direction to evenly spread the first powder pushed out of the powder supply cylinder 210 onto the entire forming area 120 to form a first powder layer of uniform thickness.

[0027] The second powder spreading assembly 300 includes a powder suction pipe 310, a powder feeding mechanism 320, and a second scraper 330. The powder suction pipe 310, the powder feeding mechanism 320, and the second scraper 330 are connected to a motion mechanism 350 disposed on the top surface of the inner wall of the forming chamber 100 via a connecting plate 340. The motion mechanism 350 can drive the powder suction pipe 310, the powder feeding mechanism 320, and the second scraper 330 to move horizontally. Specifically, the powder suction pipe 310, the powder feeding mechanism 320, and the second scraper 330 are respectively fixedly installed on the connecting plate 340, and the three are arranged in sequence horizontally. The motion mechanism 350 is disposed on the top surface of the inner wall of the forming chamber 100. The motion mechanism 350 drives the connecting plate 340 to move horizontally, thereby moving the powder suction pipe 310, the powder feeding mechanism 320, and the second scraper 330 as a whole horizontally to a preset position above the forming area 120. The forming chamber 100 is provided with one or more sets of second powder spreading components 300. When multiple sets of second powder spreading components 300 are provided in the forming chamber 100, the multiple sets of second powder spreading components 300 can correspond to different powder materials respectively, thereby realizing the composite forming of three or more materials in the same part. The multiple sets of second powder spreading components 300 are arranged in sequence along the horizontal direction, and each set does not interfere with the others.

[0028] The powder suction pipe 310 is connected to the negative pressure powder suction tank via a pipeline, and the negative pressure powder suction tank is separately installed from the forming chamber 100. Specifically, the powder suction pipe 310 has a hollow tubular structure, with its lower end opening towards the forming area 120, and its upper end connected to the negative pressure powder suction tank via a pipeline. The negative pressure powder suction tank is located outside the forming chamber 100 and is separate from it. The negative pressure powder suction tank generates negative pressure inside through a vacuum pump to suck up and collect the powder. A preset distance is maintained between the lower end opening of the powder suction pipe 310 and the surface of the powder layer to ensure effective powder removal while avoiding interference with the surface of the molten and formed parts. The separate installation of the negative pressure powder suction tank and the forming chamber 100 prevents the vibration of the negative pressure powder suction tank from being transmitted into the forming chamber 100 and affecting the powder spreading accuracy. It also facilitates independent cleaning and maintenance of the negative pressure powder suction tank without opening the forming chamber 100.

[0029] like Figure 2As shown, the powder feeding mechanism 320 includes a powder feeding bin 322 and a screw valve 323 fixed on the frame 321. The top of the frame 321 is fixedly connected to the connecting plate 340. The powder feeding bin 322 is connected to the feed end of the screw valve 323. The screw inside the screw valve 323 is connected to the motor 324 for transmission. The motor 324 is used to drive the screw to rotate so as to discharge the second powder in the powder feeding bin 322 from the discharge end 325 of the screw valve 323 in a metered manner. Specifically, the top of the frame 321 is fixedly connected to the connecting plate 340, so that the powder feeding mechanism 320 is suspended below the connecting plate 340. The powder feeding bin 322 is fixedly installed on the frame 321, and its bottom outlet is connected to the feed end of the screw valve 323. The powder feeding bin 322 is used to store the second powder, which is a material powder different from the first powder. The screw valve 323 includes a valve body and a screw set inside the valve body. The outer surface of the screw is provided with a spiral groove. When the screw rotates, the spiral groove pushes the second powder from the feed end to the discharge end 325 to achieve quantitative discharge. The discharge end 325 of the screw valve 323 is set downward, so that the second powder falls onto the surface of the forming area 120 under the action of gravity. Motor 324 is either a servo motor 324 or a stepper motor 324. Motor 324 is connected to the screw drive of screw valve 323 through a reduction gearbox. The number of rotations or rotation angle of motor 324 can be adjusted to adjust the single discharge amount of screw valve 323. Specifically, by controlling the number of pulses or rotation angle of servo motor 324 or stepper motor 324, the number of rotations of screw can be precisely controlled, thereby achieving precise control of the second powder feeding amount.

[0030] Reference Figure 3 The second scraper 330 includes a fixed plate 331, a drive unit 332, and a scraper holder 333. The top of the fixed plate 331 is fixedly connected to the connecting plate 340. The drive unit 332 is fixed on one side of the fixed plate 331 and connected to the scraper holder 333. A blade head 334 is mounted on the scraper holder 333. The drive unit 332 is used to drive the scraper holder 333 and the blade head 334 to reciprocate in the vertical direction. Specifically, the fixing plate 331 is a vertical plate structure, with its top end fixedly connected to the connecting plate 340. The driving unit 332 is fixed to one side of the fixing plate 331, and its output end is connected to the scraper holder 333, driving the scraper holder 333 to reciprocate vertically. A blade head 334 is mounted on the scraper holder 333, which is used to scrape the second powder. The blade head 334 is mounted on the scraper holder 333 by a snap-fit ​​method, which facilitates the replacement of different specifications of blade heads 334 according to the size of the second powder melting zone 122. When powder spreading is required, the driving unit 332 drives the scraper holder 333 to descend, so that the bottom edge of the blade head 334 is at a preset powder spreading height with the surface of the second powder melting zone 122. After the powder spreading is completed, the driving unit 332 drives the scraper holder 333 to rise, so that the blade head 334 is removed from the powder layer surface, and the second powder spreading assembly 300 returns to the standby state.

[0031] Continue to refer to Figure 3 Guide components are provided on both sides of the drive unit 332. Each guide component includes a guide rod 335 and a linear bearing 336. The linear bearing 336 is mounted vertically on the fixed plate 331. The guide rod 335 passes through the linear bearing 336 and can slide vertically. The bottom end of the guide rod 335 is connected to the scraper holder 333. A limit ring 337 is provided at the upper end of the guide rod 335 to limit the lifting stroke of the cutter head 334. Specifically, the guide components are symmetrically arranged on both sides of the drive unit 332. Each set of guide components includes a guide rod 335 and a linear bearing 336. The linear bearing 336 is mounted vertically on the fixed plate 331. The guide rod 335 passes through the linear bearing 336 and can slide freely vertically, providing precise vertical guidance for the lifting movement of the scraper holder 333 and preventing the scraper holder 333 from tilting or swaying during lifting. The bottom end of the guide rod 335 is connected to the scraper holder 333. The connection 33 allows the scraper holder 333 and the guide rod 335 to rise and fall synchronously. The upper end of the guide rod 335 is provided with a limit ring 337. When the scraper holder 333 rises to the highest position, the limit ring 337 abuts against the upper end face of the linear bearing 336 or the upper end face of the fixing plate 331, thereby limiting the maximum lifting height of the cutter head 334, that is, limiting the lifting stroke of the cutter head 334. By adjusting the fixed position of the limit ring 337 on the guide rod 335, the lifting stroke range of the cutter head 334 can be adjusted.

[0032] like Figure 4 As shown, this embodiment also provides a multi-material laser powder bed fusion additive manufacturing method, which uses the above-mentioned powder spreading device and includes the following steps: Step S1: Drive the first scraper 220 to reciprocate linearly along the forming area 120, spreading the first powder over the entire forming area 120 to form a first powder layer. Specifically, the piston of the powder supply cylinder 210 moves upward by a layer thickness, pushing the first powder out from the opening of the powder supply cylinder 210. Driven by the driving mechanism, the first scraper 220 reciprocates linearly in the horizontal direction from one side of the powder supply cylinder 210 to the other side of the forming area 120, evenly spreading the pushed-out first powder over the entire forming area 120, including the first powder melting zone 121 and the second powder melting zone 122, forming a first powder layer with a thickness equal to one layer thickness.

[0033] Step S2: The laser system is driven to selectively scan and melt the first powder layer within the first powder melting zone 121 according to the preset scanning and melting path of the first powder. Specifically, the laser system selectively scans and melts the first powder layer within the first powder melting zone 121 according to the pre-introduced preset scanning and melting path of the first powder. During the laser scanning process, the first powder within the first powder melting zone 121 is melted and solidified to form a dense first material entity, while the first powder that is not melted by the laser remains in an unmelted state.

[0034] Step S3 involves driving the second powder spreading component 300 to move horizontally to a preset position, removing unmelted first powder from the second powder melting zone 122, and spreading the second powder within the second powder melting zone 122. Specifically, the motion mechanism 350 drives the connecting plate 340 to move horizontally, causing the powder suction pipe 310, the powder feeding mechanism 320, and the second scraper 330 to move together to a preset position above the second powder melting zone 122. Step S3 specifically includes the following sub-steps: Step S31: Drive the powder suction pipe 310 to remove the unmelted first powder using negative pressure. Specifically, the powder suction pipe 310 moves to directly above the second powder melting zone 122, and starts the vacuum pump of the negative pressure powder suction tank to generate a negative pressure airflow in the powder suction pipe 310 to remove the unmelted first powder in the second powder melting zone 122. The removed first powder enters the negative pressure powder suction tank through the pipeline for collection. During the removal process, the powder suction pipe 310 can move along the length of the second powder melting zone 122 to ensure that the unmelted first powder in the area is completely removed, exposing the top surface of the forming cylinder 110 or the surface of the formed layer.

[0035] In step S32, the powder feeding mechanism 320 is driven to quantitatively feed the second powder into the second powder melting zone 122. Specifically, the powder feeding mechanism 320 moves with the connecting plate 340 to directly above the second powder melting zone 122, and the motor 324 is started. The motor 324 drives the screw in the screw valve 323 to rotate a preset number of turns or angle through the reduction gearbox, and quantitatively discharges the second powder in the powder feeding bin 322 from the discharge end 325 of the screw valve 323 onto the surface of the second powder melting zone 122. The single discharge amount of the screw valve 323 is determined according to the area of ​​the second powder melting zone 122 and the thickness of the powder layer.

[0036] In step S33, the second scraper 330 is driven to move above the second powder melting zone 122 and descend to the preset powder spreading height. Specifically, the second scraper 330 moves with the connecting plate 340 to directly above the second powder melting zone 122, and the drive unit 332 drives the scraper holder 333 to descend vertically, so that the gap between the bottom edge of the cutter head 334 and the surface of the second powder melting zone 122 is equal to the preset powder spreading height. The guide rod 335 slides down synchronously in the linear bearing 336 to provide vertical guidance for the descent of the scraper holder 333.

[0037] Step S34: Drive the second scraper 330 to move horizontally and scrape the second powder placed in the second powder melting zone 122. Specifically, the motion mechanism 350 drives the connecting plate 340 to move horizontally, causing the second scraper 330 to make unidirectional or reciprocating linear motion along the length of the second powder melting zone 122, scraping the second powder placed in the second powder melting zone 122 to make the thickness of the second powder layer equal to the preset powder spreading height. During the scraping process, excess second powder is pushed to the edge of the second powder melting zone 122 by the cutter head 334.

[0038] Step S35: Drive the second scraper 330 to lift, so that the second powder spreading assembly 300 returns to the standby state. Specifically, after the powder spreading is completed, the drive unit 332 drives the scraper holder 333 to rise in the vertical direction, and the guide rod 335 slides synchronously in the linear bearing 336 until the limit ring 337 abuts against the upper end face of the fixing plate 331, the cutter head 334 disengages from the powder layer surface, and the second powder spreading assembly 300 returns to the standby state as a whole, waiting for the next layer cycle.

[0039] Step S4: Drive the laser system to selectively scan and melt the second powder in the second powder melting zone 122 according to the preset scanning and melting path of the second powder. Specifically, the laser system selectively scans and melts the second powder in the second powder melting zone 122 according to the preset scanning and melting path of the second powder. The scanning strategy of the preset scanning and melting path of the second powder can be the same as or different from the preset scanning and melting path of the first powder, and can be set according to the material characteristics of the second powder.

[0040] Step S5: Drive the powder suction tube 310 to move above the second powder melting zone 122 and remove the unmelted second powder. Specifically, after the selective scanning melting of the second powder is completed, there is still excess second powder in the second powder melting zone 122 that has not been melted by the laser. The motion mechanism 350 drives the connecting plate 340 to move, so that the powder suction tube 310 moves directly above the second powder melting zone 122. Start the vacuum pump of the negative pressure powder suction tank to remove the unmelted second powder and collect it into the negative pressure powder suction tank. After the removal is completed, only the melted and solidified second material entity is left in the second powder melting zone 122.

[0041] In step S6, the forming cylinder 110 is driven to move downwards by one layer thickness, and the process returns to step S1 to continue powder spreading and selective scanning melting, layer by layer, until the additive manufacturing of the multi-material composite part is completed. Specifically, the lifting drive mechanism of the forming cylinder 110 drives the forming cylinder 110 to move downwards by one layer thickness, so that the top surface of the formed layer drops by one layer thickness, providing space for the next layer of powder spreading. Then, the process returns to step S1, and the steps of global powder spreading, selective scanning melting, and powder replacement are repeated, layer by layer, until all layers of the part are formed, completing the additive manufacturing of the multi-material composite part. After forming is completed, the forming chamber 100 is opened, the forming cylinder 110 is taken out, and the formed part is taken out of the forming cylinder 110.

[0042] As a variation of this embodiment, two sets of second powder-laying assemblies 300 are provided in the forming chamber 100. The two sets of second powder-laying assemblies 300 are arranged sequentially in the horizontal direction in the forming chamber 100 and are respectively connected to the motion mechanism 350 through their respective connecting plates 340. The powder feeding bins 322 of the two sets of second powder-laying assemblies 300 respectively store powders of different materials. The forming area 120 is correspondingly divided into a first powder melting zone 121, a second powder melting zone 122, and a third powder melting zone. In the additive manufacturing process, after step S1 is completed, the first set of second powder-laying assemblies 300 sequentially performs powder replacement and powder laying on the second powder melting zone 122, and the second set of second powder-laying assemblies 300 sequentially performs powder replacement and powder laying on the third powder melting zone, thereby realizing the composite forming of three materials in the same part. Those skilled in the art will understand that the number of second powder-laying assemblies 300 provided in the forming chamber 100 is not limited to two sets, and three or more sets can be set according to the number of material types required for the part.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-material laser powder bed melting additive manufacturing method, implemented using a multi-material laser powder bed melting powder spreading device, the powder spreading device comprising a laser system for selectively scanning and melting powder layers, a forming chamber (100), a first powder spreading component (200), and a second powder spreading component (300). A forming cylinder (110) is provided at the bottom of the forming chamber (100). The bottom surface of the inner wall of the forming chamber (100) is provided with a forming area (120) corresponding to the forming cylinder (110). The forming area (120) includes a first powder melting area (121) and a second powder melting area (122); The first powder spreading assembly (200) includes a powder supply cylinder (210) and a first scraper (220); The powder supply cylinder (210) is located at the bottom of the forming chamber (100) and is used to store the first powder; The first scraper (220) is disposed in the forming chamber (100) and is capable of moving horizontally along the bottom surface of the inner wall; The second powder spreading component (300) includes a powder suction tube (310), a powder feeding mechanism (320), and a second scraper (330); The powder suction pipe (310), the powder feeding mechanism (320), and the second scraper (330) are connected to the motion mechanism (350) disposed on the top surface of the inner wall of the forming chamber (100) via a connecting plate (340); The motion mechanism (350) can drive the powder suction tube (310), the powder feeding mechanism (320) and the second scraper (330) to move in the horizontal direction; The powder feeding mechanism (320) is used to store the second powder, characterized in that, The additive manufacturing method includes the following steps: S1. Drive the first scraper (220) to reciprocate linearly along the forming area (120) to spread the first powder over the entire forming area (120) to form a first powder layer; S2. Drive the laser system to selectively scan and melt the first powder layer in the first powder melting zone (121) according to the preset scanning and melting path of the first powder; S3. Drive the second powder spreading component (300) to move horizontally to a preset position, remove the unmelted first powder in the second powder melting zone (122), and spread the second powder in the second powder melting zone (122); S4. Drive the laser system to selectively scan and melt the second powder in the second powder melting zone (122) according to the preset scanning and melting path of the second powder; S5. Drive the powder suction tube (310) to move above the second powder melting zone (122) to remove the unmelted second powder; S6. Drive the forming cylinder (110) downward by one layer thickness distance, return to step S1 to continue to perform powder spreading and selective scanning melting, and cyclically stack layer by layer until the additive manufacturing of multi-material composite parts is completed.

2. The multi-material laser powder bed fusion additive manufacturing method according to claim 1, characterized in that, The powder suction pipe (310) is connected to the negative pressure powder suction tank through a pipeline, and the negative pressure powder suction tank is separately set from the forming chamber (100).

3. The multi-material laser powder bed fusion additive manufacturing method according to claim 1, characterized in that, The powder feeding mechanism (320) includes a powder feeding bin (322) and a screw valve (323) fixed on the frame (321). The top of the frame (321) is fixedly connected to the connecting plate (340); The powder feeding hopper (322) is connected to the feed end of the screw valve (323); The screw inside the screw valve (323) is connected to the motor (324) for transmission. The motor (324) is used to drive the screw to rotate so as to discharge the second powder in the powder feeding bin (322) from the discharge end (325) of the screw valve (323) in a metered manner.

4. The multi-material laser powder bed fusion additive manufacturing method according to claim 3, characterized in that, The motor (324) is a servo motor (324) or a stepper motor (324). The motor (324) is connected to the screw of the screw valve (323) through a reduction gearbox. The number of rotations or the rotation angle of the motor (324) can be adjusted to adjust the single output of the screw valve (323).

5. The multi-material laser powder bed fusion additive manufacturing method according to claim 1, characterized in that, The second scraper (330) includes a fixing plate (331), a drive unit (332), and a scraper holder (333); The top end of the fixing plate (331) is fixedly connected to the connecting plate (340); The drive unit (332) is fixed to one side of the fixed plate (331) and connected to the scraper holder (333), and the scraper holder (333) is fitted with a blade head (334). The drive unit (332) is used to drive the scraper holder (333) and the blade head (334) to reciprocate in the vertical direction.

6. The multi-material laser powder bed fusion additive manufacturing method according to claim 5, characterized in that, The drive unit (332) is provided with guide components on both sides, and the guide components include guide rods (335) and linear bearings (336). The linear bearing (336) is mounted on the fixed plate (331) in a vertical direction, and the guide rod (335) passes through the linear bearing (336) and can slide in a vertical direction; The bottom end of the guide rod (335) is connected to the scraper holder (333), and the upper end of the guide rod (335) is provided with a limit ring (337) to limit the lifting stroke of the cutter head (334).

7. The multi-material laser powder bed fusion additive manufacturing method according to claim 1, characterized in that, The forming chamber (100) is provided with one or more sets of the second powder spreading components (300).

8. The multi-material laser powder bed fusion additive manufacturing method according to claim 1, characterized in that, Step S3 specifically includes: S31. Drive the powder suction tube (310) to remove the unmelted first powder using negative pressure; S32. Drive the powder feeding mechanism (320) to quantitatively feed the second powder into the second powder melting zone (122); S33. Drive the second scraper (330) to move above the second powder melting zone (122) and lower it to the preset powder spreading height; S34. Drive the second scraper (330) to move horizontally and scrape the second powder placed in the second powder melting zone (122); S35. Drive the second scraper (330) to lift, so that the second powder spreading component (300) returns to the standby state.

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