3D printing device and method based on laser melting heterogeneous material surface layer additive material

Abstract

The invention relates to a 3D printing device and method based on laser melting heterogeneous material surface layer additive, the device comprises a support table, a rotating assembly, a laser melting assembly and a feeding assembly, the rotating assembly, the laser melting assembly and the feeding assembly are installed on the support table, and the rotating assembly is used for fixing blades and driving the blades to rotate; the laser melting assembly is used for conducting matrix pit printing treatment on the surface of the blade. According to the method, laser pit point printing treatment is conducted on the surface of the blade, so that a uniform high-density pit surface is formed on the surface of the blade, then high-temperature alloy powder is sprayed into pits, meanwhile, melting treatment is conducted through laser, and metal piles distributed in a high-density matrix mode are planted on the surface of the whole blade; and after the surface of the blade is continuously subjected to powder spraying and laser melting treatment, the whole blade coating and the metal pile are combined in a high-strength mode due to the homogeneous material, and the problem that the whole coating on the dissimilar metal surface is prone to falling off is effectively solved.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing technology, and particularly to a 3D printing device and method for additive manufacturing of the surface layer of heterogeneous materials based on laser melting. Background Art

[0002] As an important technology in the field of material protection, metal spraying forms a new coating layer by spraying a high-speed particle flow of molten metal on the surface of a substrate, so as to improve the wear resistance and high-temperature resistance of mechanical parts. For example, various parts in aircraft engines, after being sprayed with high-temperature metals, cermets or special refractory materials, etc., the overhaul period can be extended from several thousand hours to tens of thousands of hours. On the surface of ordinary steel materials that are easily worn in machinery and equipment, spraying high-chromium metal by plasma spraying can extend the service life of the machinery and equipment by more than twice.

[0003] Currently, for the application of metal spraying technology in the industry, most rely on compressed air to blow the melted metal into a mist through a spray gun and spray it on the surface of a rapid prototyping workpiece (substrate), and quickly solidify to form a metal thin shell. However, this technology has the following disadvantages: when applied to the surfaces of metals made of different materials, the coating formed after the heterogeneous metals are fused with each other has a low strength and is extremely easy to fall off during use; at the same time, due to the lack of the ability of 3D all-round spraying with multi-axis linkage, the spraying effect on the surface of complex substrates is uneven, and it cannot meet the requirements of high-precision processing. Specifically, taking the patent with the application number 201710534002 as an example, although the additive manufacturing system proposed in its disclosed patent uses a rotary multi-nozzle switching printing device to achieve multi-material switching printing, this solution not only depends on a 3D printer for the manufacture of the product matrix, with high costs and low production efficiency, but also the problem of easy coating peeling still cannot be effectively solved when dealing with the substrate material and the sprayed heterogeneous material. Furthermore, currently in the industry, to increase the working temperature of turbine blade parts of jet aircraft and various gas turbines and extend their service life, harsh requirements are put forward for the protective coating, especially the bond strength of the coating on the surface of turbine blades working under hot corrosion conditions. Therefore, traditional diffusion aluminide coatings and aluminide-silicon coatings can no longer meet the working requirements of high-pressure turbine blades for high-temperature oxidation resistance and high-temperature gas erosion resistance, and can only be used for the protection of the surfaces of low-pressure turbine guides and fairing struts. Furthermore, the industry actively explores, and there are the following two new metal coating processes: 1. Plasma spray coatings have been applied to gas turbine turbine blades. Currently, in use, plasma-sprayed CoCrAlSiY / ZrO2 coatings are mainly applied to high-pressure turbine guides.

[0004] 2. Electron beam CoCrAlSiY / ZrO2 coatings are mainly applied to the surfaces of high-pressure turbine moving blades and the surfaces of high-temperature components of gas turbines; Although these two processes have brought new breakthroughs in high-temperature protection, there are still defects: after the surface metal is melted by spraying, the connection strength between the two heterogeneous spraying materials is low and easy to fall off, resulting in a reduced service life of the high-temperature blade. Summary of the Invention

[0005] The present invention provides a 3D printing device and method based on laser melting of heterogeneous material surface layer additive manufacturing to solve the problems raised in the above-mentioned background technology.

[0006] To solve the above technical problems, the technical solutions adopted by the present invention are as follows: A 3D printing device based on laser melting of heterogeneous material surface layer additive manufacturing includes a support table, a rotating assembly, a laser melting assembly, and a feeding assembly respectively installed on the support table. The rotating assembly is used to fix the blade and drive the blade to rotate. The laser melting assembly is used to perform matrix pit printing on the blade surface and melt the powder ejected by the feeding assembly. The feeding assembly is used to spray powder into the matrix pits and onto the blade surface and perform a rolling operation on the sprayed powder.

[0007] Preferably, the laser melting assembly includes a laser melting emission device, a printer light source, a position sensor, a melting workbench, a first driving part, a second driving part, and a third driving part. The laser melting emission device is used for matrix pit printing and powder melting processing. The cooperation of the first driving part, the second driving part, and the third driving part is used to drive the laser melting emission device, the printer light source, and the position sensor to move synchronously along the X-axis, Y-axis, and Z-axis.

[0008] Preferably, the feeding assembly includes a feeding bin, a powder nozzle, a fourth driving part, a fifth driving part, and a rolling wheel. The powder nozzle is used to spray the powder in the feeding bin onto the surface of the blade or the inner cavity of the pit. The cooperation of the fourth driving part and the fifth driving part is used to drive the feeding bin and the powder nozzle to move synchronously along the X-axis and Z-axis, and the powder nozzle is replaced by a rolling wheel through an automatic replacement mechanism.

[0009] Preferably, the rotating assembly includes a blade positioning part and a blade rotating part. The blade positioning part is used to fix the blade, and the blade rotating part is used to drive the fixed blade to rotate.

[0010] Preferably, the blade positioning part is a blade fixing tenon tooth, and the blade rotating part is a pair of symmetrically arranged rotating driving mechanisms and a rotating workbench fixing mechanism. The rotating driving mechanism is installed on the support table.

[0011] Preferably, the rotating driving mechanism is connected to the powder nozzle through a linkage mechanism.

[0012] Preferably, the matrix pits processed by the laser melting assembly are all in a horn-shaped structure that gradually increases from the surface of the blade inward.

[0013] Preferably, the depth of the pits is 500 - 2000 μm.

[0014] Preferably, in the matrix pits processed by the laser melting assembly, the distance between every two pits is 1000 - 3000 μm.

[0015] A printing method of a 3D printing device for additive manufacturing on the surface of a laser - melted heterogeneous material includes the following steps: S100: Place the blade to be processed on the blade positioning part and fix it by the blade positioning part; S200: Start the blade rotating part to drive the blade to rotate at a set speed. At the same time, control the laser melting emission device to move along the X - axis, Y - axis or Z - axis, and perform dot - matrix laser pit printing on the surface of the blade according to a preset dot - matrix pattern, so as to form a uniformly distributed high - density matrix of pits on the surface of the blade; S300: Continuously maintain the rotation of the blade, and use the powder nozzle in the feeding assembly to spray metal powder into each pit one by one according to the layout of the matrix pits until all the pits are completely filled with metal powder; S400: During the continuous rotation of the blade, in cooperation with the movement of the laser melting emission device, make the laser melting emission device emit a high - energy laser beam to melt the metal powder in the pits, so that the metal powder melts and solidifies, promoting the formation of multiple metal posts on the surface of the blade; S500: Based on the rotation of the blade, uniformly spray powder on the whole surface of the blade through the powder nozzle, and after powder spraying, trigger the automatic replacement mechanism to quickly replace the powder nozzle with a rolling wheel, and make the rolling wheel roll the powder on the surface of the blade; S600: Drive the blade to rotate through the rotating assembly, and control the laser melting emission device to move along the planned path, so that the laser beam emitted by the laser melting emission device can perform laser melting on the powder on the surface of the blade, promoting the melting of the powder and the fusion with multiple metal posts to complete the first - layer printing on the surface of the blade; S700: Repeat steps S500 and S600, continuously perform powder spraying, rolling and laser melting operations, and gradually increase the layer thickness of the metal printing on the surface of the blade in a layer - by - layer stacking manner until the preset layer - thickness requirement is reached. At this point, the printing work ends.

[0016] By adopting the above technical solutions, the beneficial effects obtained by the present invention are: In the present invention, by first performing dot matrix laser pit printing treatment on the blade surface, a uniform high-density concave pit surface is formed on the blade surface. Then, spraying superalloy powder into the high-density surface pits, and using the laser to melt the superalloy powder, so as to promote the planting of metal piles with a high-density matrix distribution on the entire blade surface. Subsequently, after continuous powder spraying and laser melting treatment on the blade surface, the entire blade coating and the metal piles are strongly bonded due to the same homogeneous material, effectively improving the service life of the blade, and at the same time effectively solving the problem that the overall coating on the surface of dissimilar metals is prone to peeling off.

[0017] In the present invention, through the mutual cooperation of the first driving part, the second driving part, the third driving part, the fourth driving part and the fifth driving part, the spraying effect on the blade surface is effectively guaranteed to be uniform, and the high-precision processing of the blade surface coating is ensured. Brief Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of the laser melting component of the present invention.

[0020] Figure 3 It is a schematic diagram of the matrix of the pits on the blade surface of the present invention.

[0021] Figure 4 It is a schematic cross-sectional view of the pit of the present invention.

[0022] Figure 5 It is a flow chart of the printing method of the present invention.

[0023] In the figure: 1. Support platform; 2. Rotating assembly; 21. Rotating drive mechanism; 22. Rotating workbench fixing mechanism; 23. Blade fixing dovetail teeth; 3. Laser melting component; 31. Laser melting emission device; 32. Printer light source; 33. Position sensor; 34. Melting workbench; 35. First driving part; 36. Second driving part; 37. Third driving part; 4. Feeding component; 41. Feeding bin; 42. Powder nozzle; 43. Fourth driving part; 44. Fifth driving part; 5. Blade; 6. Pit. Detailed Embodiments

[0024] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the following further describes the present invention with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0025] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the limitations of the specific embodiments disclosed in the following specification. Embodiment 1

[0026] As shown in Figures 1-4 the figure, the present invention provides a 3D printing device for additive manufacturing of the surface layer of a laser-fused heterogeneous material, including a support table 1, a rotating assembly 2, a laser melting assembly 3, and a feeding assembly 4 respectively installed on the support table 1. The rotating assembly 2 is used to fix the blade 5 and drive the blade 5 to rotate. The laser melting assembly 3 is used to perform matrix pit 6 printing on the surface of the blade 5 and melt the superalloy powder ejected by the feeding assembly 4. The feeding assembly 4 is used to spray the superalloy powder into the matrix pit 6 and onto the surface of the blade 5 and roll the sprayed superalloy powder.

[0027] Furthermore, the laser melting assembly 3 includes a laser melting emission device 31, a printer light source 32, a position sensor 33, a melting workbench 34, a first driving part 35, a second driving part 36, and a third driving part 37. The laser melting emission device 31 is used for the printing of the matrix pit 6 and the treatment of powder melting. The cooperation of the first driving part 35, the second driving part 36, and the third driving part 37 is used to drive the laser melting emission device 31, the printer light source 32, and the position sensor 33 to move synchronously along the X-axis, Y-axis, and Z-axis.

[0028] Specifically, the laser melting emission device 31, the printer light source 32, and the position sensor 33 are commonly installed on a moving seat plate, and the first driving part 35, the second driving part 36, and the third driving part 37 are respectively used to drive the moving seat plate to move along the X-axis, Y-axis, and Z-axis. It should be emphasized that the structures of the first driving part 35, the second driving part 36, and the third driving part 37 are all conventional technologies in this technical field and are well known and applied by those skilled in the art. And the driving parts of the first driving part 35, the second driving part 36, and the third driving part 37 may specifically be the cooperation of a servo motor and a lead screw, or the cooperation of a servo motor and a synchronous belt and a synchronous pulley; and when each driving component cooperates, those skilled in the art can cooperate with a gearbox and an optical axis guide according to specific circumstances to ensure the stability of the moving seat plate during movement and improve the accuracy of the laser melting emission device 31 during operation.

[0029] As a further step, a 3D printing device based on laser melting of heterogeneous material surface additive also includes a rectangular frame and a pair of vertical plates, the pair of vertical plates are fixedly mounted on the support table 1, the third drive unit 37 is fixedly mounted on the pair of vertical plates, the second drive unit 36 is fixedly mounted on the rectangular frame, and the first drive unit 35 is fixedly mounted on the slide of the second drive unit 36; thus, when the third drive unit 37 is started, it can drive the rectangular frame to move forward and backward, thereby realizing the Z-axial movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33; and when the second drive unit 36 is started, it can drive the slide to move up and down, thereby realizing the Y-axial movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33; when the first drive unit 35 is started, it can drive the movable seat plate to move left and right, thereby realizing the X-axial movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33.

[0030] Furthermore, the feeding assembly 4 includes a feeding bin 41, a feeding bin 41, a fourth driving unit 43, a fifth driving unit 44 and a rolling wheel. The powder nozzle 42 is used to spray the powder in the feeding bin 41 onto the surface of the blade 5 or the inner cavity of the pit 6. The cooperation of the fourth driving unit 43 and the fifth driving unit 44 is used to drive the feeding bin 41 and the powder nozzle 42 to move synchronously along the X-axis and the Z-axis, and the powder nozzle 42 is replaced by the rolling wheel through an automatic replacement mechanism.

[0031] Specifically, it should be noted that in this solution, the technology of the automatic replacement mechanism replacing the powder nozzle 42 with a rolling wheel, as well as the structures of the fourth drive unit 43 and the fifth drive unit 44, are conventional technologies in this field, and the technology of the automatic replacement mechanism has been widely used in the market. Its technical principle can refer to the automatic tool replacement technology of mechanical CNC machining centers; and the structure of the fourth drive unit 43 and the fifth drive unit 44 can both be driven by a servo motor to drive the screw to rotate, and the screw drives the mobile mounting platform to drive the feed bin 41 and the powder nozzle 42 to move forward, backward, left and right. It is worth noting that the description of this in this solution is to ensure the authenticity and feasibility of the embodiment of this solution, but the fourth drive unit 43 and the fifth drive unit 44 in the present invention include but are not limited to servo motor drive and screw.

[0032] Furthermore, the fourth driving unit 43 and the fifth driving unit 44 further include cable threading chains respectively.

[0033] Furthermore, the rotating assembly 2 includes a blade positioning part and a blade rotating part, the blade positioning part is used to fix the blade 5, and the blade rotating part is used to drive the fixed blade 5 to rotate; wherein, the blade positioning part is a blade fixing falcon tooth 23, and the blade rotating part is a pair of symmetrically arranged rotating drive mechanisms 21 and a rotating worktable fixing mechanism 22, and the rotating drive mechanism 21 is installed on the support platform 1.

[0034] Furthermore, the rotary drive mechanism 21 is connected to the powder nozzle 42 through a linkage mechanism, wherein the rotary drive mechanism 21 for rotating the blade 5 and the powder nozzle 42 of the 3D laser printing device are in a linkage relationship, thereby jointly realizing powder spraying, powder rolling and laser melting of the curved surface of the blade 5.

[0035] As a further step, the matrix pits 6 printed and processed by the laser melting component 3 are all trumpet-shaped structures that gradually increase in size from the surface of the blade 5 inward. Specifically, the characteristics of the pits 6 are: the shape of the pits is a trumpet-shaped shape that is large inside and small outside. When the laser ablates the pits, the ablation time of the pit bottom is longer than that of the pit mouth.

[0036] Furthermore, in the matrix pits 6 printed and processed by the laser melting component 3, the distance between each two pits 6 is 1000~3000μm, and the depth of each pit 6 is 500~2000μm. When the laser ablates the pit point, the ablation time of the pit bottom is three times longer than that of the pit mouth. Example 2

[0037] Combine Figures 1-5 As shown, the present invention also provides a printing method of a 3D printing device based on laser melting of a heterogeneous material surface additive, which mainly provides a method for additively printing the surface of a blade 5 made of ordinary metal 17-4PH material with metal powder of another titanium alloy material. The other titanium alloy material is specifically titanium alloy 6AL-4V Ti gold powder sprayed as an example, which specifically includes the following steps: S100, placing the blade 5 to be processed on the blade positioning part, and fixing it by the blade positioning part to ensure that the blade 5 does not move or shake during the subsequent processing; S200, starting the blade rotating unit to drive the blade 5 to rotate at a set speed, and at the same time controlling the laser melting emission device 31 to move along the X-axis, Y-axis or Z-axis, performing a dot matrix laser pit printing process on the surface of the blade 5 according to a preset dot matrix pattern, so that a high-density matrix of pits 6 with uniform distribution is formed on the surface of the blade 5; Among them, when the first driving part 35 is started, it can drive the movable base plate to move left and right, thereby realizing the X-axis movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33; When the second driving unit 36 is activated, the slide table can be driven to move up and down, thereby realizing the Y-axis movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33; When the third driving unit 37 is activated, it can drive the rectangular frame to move forward and backward, thereby realizing the Z-axis movement of the laser melting emission device 31, the printer light source 32 and the position sensor 33; S300, while maintaining the rotation of the blade 5, the powder nozzle 42 in the feeding assembly 4 sprays metal powder into each of the pits 6 one by one according to the layout of the matrix pits 6 until all the pits 6 are completely filled with metal powder; Among them, the rotary drive mechanism 21 for rotating the blade 5 and the powder nozzle 42 of the 3D laser printing device are in a linkage relationship, so that powder spraying, powder rolling and laser melting of the curved surface of the blade 5 can be achieved. It is worth noting that changes in parameters such as the rotation speed and direction of the rotary drive mechanism 21 will directly affect the moving speed, angle or powder injection amount of the powder nozzle 42 of the 3D laser printing device to achieve specific 3D printing functions or process requirements. This linkage relationship is usually achieved through a specific mechanical structure, transmission device or control system to ensure that the movements of the two can be precisely coordinated, thereby ensuring the accuracy and stability of the 3D printing process. This technology is already well known and applied by those skilled in the art, and this article will not elaborate on it in detail. S400, while the blade 5 is rotating, the laser melting emitting device 31 is moving, so that the laser melting emitting device 31 emits a high-energy laser beam to melt the metal powder in the pit 6, causing the metal powder to melt and solidify, thereby forming a plurality of metal piles on the surface of the blade 5; S500: Based on the rotational motion of the blade 5, the entire surface of the blade 5 is evenly powder-sprayed through the powder nozzle 42. After the powder spraying, the automatic replacement mechanism is triggered to quickly replace the powder nozzle 42 with a rolling wheel, so that the rolling wheel rolls the powder on the surface of the blade 5 to improve the density and flatness of the powder. Specifically, the powder nozzle 42 sprays atomized high-temperature alloy powder onto the surface of the blade 5. It is worth noting that the characteristics of the high-temperature alloy powder are: the high-temperature alloy powder is mixed with an organic flux and high-pressure air in the 3D printer feed bin 41 to form atomized particles with a certain viscosity; S600: The blade 5 is driven to rotate by the rotating assembly 2, and the laser melting emission device 31 is controlled to move along the planned path, so that the laser beam emitted by the laser melting emission device 31 can perform a laser melting process on the powder on the surface of the blade 5, causing the powder to melt and fuse with the multiple metal piles to complete the first layer printing on the surface of the blade 5; S700, repeating steps S500 and S600, continuing the powder spraying, rolling and laser melting operations, so as to gradually increase the thickness of the metal printing layer on the surface of the blade 5 by stacking, until the preset layer thickness requirement is reached, and the printing work is completed.

[0038] The present invention adopts 3D printing to perform dot matrix laser pit printing treatment on the metal object to be electroplated (i.e., the blade 5) in advance, so as to form a uniform high-density concave pit 6 surface on the surface of the blade 5. Then, a superalloy powder is sprayed into the high-density concave pits 6 on the surface, and the superalloy powder in the concave pits 6 is subjected to selective laser melting treatment by laser, thus completing the treatment of planting high-density matrix-distributed metal piles on the entire metal surface. And since the metal piles and the powder to be sprayed on the whole blade 5 later are of the same material, after the subsequent powder spraying and laser melting treatment on the surface of the blade 5, the bonding strength between the entire blade 5 coating and the metal piles densely distributed on the surface, which are of the same material, is much higher than the bonding strength between the coating and the heterogeneous material of the part substrate. It is equivalent to adding uniformly distributed solder joints to the surface coating of the metal part, greatly improving the working life of the surface coating of the metal part, and effectively solving the problem of low spraying connection strength and easy shedding due to different materials between the surface-sprayed metal material and the substrate material.

[0039] It should be emphasized that the present invention only provides a physical architecture and does not involve the protection of software program algorithms. The introduction of existing software program algorithm technologies in this article is only for a supplementary explanation of the feasibility and authenticity of the present invention, and the present invention does not seek protection for control program algorithm technologies.

[0040] In the present invention, the term "a plurality of" refers to two or more, unless otherwise clearly defined. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. Terms such as "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] It should be noted that when an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation manner.

[0042] In the description of this specification, the descriptions of the terms "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0043] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A 3D printing device based on surface additive manufacturing of laser-melted heterogeneous materials, characterized in that, It includes a support platform (1), a rotating assembly (2), a laser melting assembly (3), and a feeding assembly (4) respectively installed on the support platform (1). The rotating assembly (2) is used to fix the blade (5) and drive the blade (5) to rotate. The laser melting assembly (3) is used to print matrix pits (6) on the surface of the blade (5) and melt the superalloy powder ejected by the feeding assembly (4). The feeding assembly (4) is used to spray superalloy powder into the matrix pits (6) and onto the surface of the blade (5), and to roll the sprayed superalloy powder.

2. The 3D printing device for surface additive manufacturing of laser-fused heterogeneous materials according to claim 1, wherein The laser melting assembly (3) includes a laser melting emission device (31), a printer light source (32), a position sensor (33), a melting workbench (34), a first driving part (35), a second driving part (36), and a third driving part (37). The laser melting emission device (31) is used for printing matrix pits (6) and melting the superalloy powder. The cooperation of the first driving part (35), the second driving part (36), and the third driving part (37) is used to drive the laser melting emission device (31), the printer light source (32), and the position sensor (33) to move synchronously along the X-axis, Y-axis, and Z-axis.

3. The 3D printing device for surface additive manufacturing of laser-fused heterogeneous materials according to claim 2, wherein The feeding assembly (4) includes a feeding bin (41), a powder nozzle (42), a fourth driving part (43), a fifth driving part (44), and a rolling wheel. The powder nozzle (42) is used to spray the superalloy powder in the feeding bin (41) onto the surface of the blade (5) or into the inner cavity of the pit (6). The cooperation of the fourth driving part (43) and the fifth driving part (44) is used to drive the feeding bin (41) and the powder nozzle (42) to move synchronously along the X-axis and Z-axis, and the powder nozzle (42) is replaced by a rolling wheel through an automatic replacement mechanism.

4. A 3D printing device for additive manufacturing of the surface layer of a laser-melted heterogeneous material according to claim 3, characterized in that, The rotating assembly (2) includes a blade positioning part and a blade rotating part. The blade positioning part is used to fix the blade (5), and the blade rotating part is used to drive the fixed blade (5) to rotate.

5. The 3D printing device based on laser melting heterogeneous material surface additive manufacturing according to claim 4, wherein, The blade positioning part is a blade fixing tenon tooth (23), and the blade rotating part is a pair of symmetrically arranged rotating driving mechanisms (21) and a rotating workbench fixing mechanism (22). The rotating driving mechanism (21) is installed on the support platform (1).

6. The 3D printing device for additive manufacturing of the surface layer of a heterogeneous material based on laser melting according to claim 5, wherein, The rotating driving mechanism (21) is connected to the powder nozzle (42) through a linkage mechanism.

7. The 3D printing device for surface additive manufacturing of laser-fused heterogeneous materials according to claim 1, wherein, The matrix pits (6) printed by the laser melting assembly (3) are all trumpet-shaped structures that gradually increase from the surface of the blade (5) inward.

8. The 3D printing device for additive manufacturing of the surface layer of a laser-melted heterogeneous material according to claim 1, wherein, The depth of the pit (6) is 500 - 2000 μm.

9. The 3D printing device for additive manufacturing of the surface layer of a heterogeneous material based on laser melting according to claim 1, characterized in that, Among the matrix pits (6) printed by the laser melting assembly (3), the distance between every two pits (6) is 1000 - 3000 μm.

10. A printing method using the 3D printing device for additive manufacturing of the surface layer of heterogeneous materials based on laser melting according to any one of claims 1-9, characterized in that, It includes the following steps: S100. Place the blade (5) to be processed on the blade positioning part and fix it by the blade positioning part; S200. Start the blade rotating part to drive the blade (5) to rotate at a set speed. At the same time, control the movement of the laser melting and emitting device (31) along the X-axis, Y-axis or Z-axis, and perform dot matrix laser pit printing on the surface of the blade (5) according to a preset dot matrix pattern, so as to form uniformly distributed high-density matrix pits (6) on the surface of the blade (5); S300. Continuously maintain the rotation of the blade (5), and spray metal powder into each pit (6) one by one through the powder nozzle (42) in the feeding assembly (4) according to the layout of the matrix pits (6) until all the pits (6) are completely filled with metal powder; S400. During the continuous rotation of the blade (5), cooperate with the movement of the laser melting and emitting device (31) to make the laser melting and emitting device (31) emit a high-energy laser beam to melt the metal powder in the pits (6), so that the metal powder melts and solidifies, and multiple metal posts are formed on the surface of the blade (5); S500. Based on the rotation of the blade (5), uniformly spray powder on the entire surface of the blade (5) through the powder nozzle (42), and trigger the automatic replacement mechanism after powder spraying to quickly replace the powder nozzle (42) with a rolling wheel, and make the rolling wheel roll the powder on the surface of the blade (5); S600. Drive the blade (5) to rotate through the rotating assembly (2), and control the movement of the laser melting and emitting device (31) along the planned path, so that the laser beam emitted by the laser melting and emitting device (31) can perform laser melting on the powder on the surface of the blade (5), and promote the melting of the powder and the fusion with multiple metal posts to complete the first layer printing on the surface of the blade (5); S700. Repeat steps S500 and S600, continuously perform powder spraying, rolling and laser melting operations, and gradually increase the layer thickness of the metal printing on the surface of the blade (5) in a layered stacking manner until the preset layer thickness requirement is reached. At this point, the printing work ends.

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