A method for preparing a closed impeller with a complex structure

Abstract

The present application discloses a method for preparing a closed impeller with a complex structure. A front cover plate product is prepared by machining; the front cover plate product is fixed on a selective laser additive manufacturing device, and blades and a first support member for supporting the blades are printed layer by layer on its inner surface to obtain a first impeller semi-finished product; the first support member in the first impeller semi-finished product is removed, and the front cover plate product and the blade part contacted by the first support member are polished to obtain a second impeller semi-finished product; the second impeller semi-finished product is fixed on a selective laser additive manufacturing device, and the rear cover plate and the second support member located at the inlet of the impeller flow channel are printed layer by layer on the side of the blade away from the front cover plate product to obtain a third impeller semi-finished product; the second support member in the third impeller semi-finished product is removed, and post-processed to obtain a finished impeller. This manufacturing method has excellent comprehensive performance, can meet high-speed and high-performance operating conditions, and has high manufacturing efficiency.

Description

Technical Field

[0001] The present application relates to the field of pump technology, and in particular to a method for preparing a closed impeller with a complex structure. Background Art

[0002] In the field of fluid machinery, impellers, as core components of equipment such as turbines, aircraft engines, expanders, pumps and compressors, undertake the key functions of pressurization or energy conversion. With the rapid development of modern industrial technology, the application environment of impellers is becoming increasingly complex and harsh, which puts higher requirements on their overall performance. Specifically, they need to have high-speed operation stability, high-pressure bearing capacity, low vibration characteristics and high-efficiency energy conversion capabilities. In order to meet these performance indicators, impeller design tends to adopt a closed structure with twisted blades and narrow gap flow channels. This design not only optimizes the fluid dynamics performance, but also significantly improves the energy conversion efficiency.

[0003] However, traditional methods face many challenges in the manufacturing process of impellers. Although five-axis machining technology has high machining accuracy and flexibility, when machining complex structures such as impellers, due to the large amount of material removal and high cutting force, it is easy to produce large stress and deformation, thus affecting the accuracy and performance of the impeller. Similarly, traditional welding methods also face the problems of large welding stress and easy deformation, and the quality and performance of welded joints are often difficult to guarantee. In addition, one-piece printed impellers often require a large number of support structures to maintain the stability of the shape during the printing process. These support structures are difficult to completely remove in subsequent processing, which not only increases the difficulty and cost of post-processing, but may also have an adverse effect on the surface quality and performance of the impeller. Summary of the invention

[0004] The embodiment of the present application provides a method for preparing a closed impeller with a complex structure, thereby solving the technical problems in the prior art that the closed impeller is prone to generate large stress and deformation when using five-axis machining and welding, and the supporting structure is difficult to completely remove when using one-piece printing.

[0005] The present application provides a method for preparing a closed impeller with a complex structure, comprising:

[0006] Prepare the front cover product by machining;

[0007] The front cover plate product is fixed on a selective laser additive manufacturing device, and blades and a first support member for supporting the blades are printed layer by layer on the inner surface thereof to obtain a first impeller semi-finished product;

[0008] Removing the first support member from the first impeller semi-finished product, and grinding the front cover plate product and the blade portion contacted by the first support member to obtain a second impeller semi-finished product;

[0009] The second impeller semi-finished product is fixed to the selective laser additive manufacturing device, and a rear cover plate and a second support member located at the inlet of the impeller flow channel are printed layer by layer on the side of the blade away from the front cover plate product to obtain a third impeller semi-finished product;

[0010] The second support member in the third impeller semi-finished product is removed and post-processed to obtain an impeller finished product.

[0011] In a possible implementation, the front cover plate product is prepared by machining, including:

[0012] The inner surface, outer surface and outer circle profile of the front cover are prepared by machining until the required size of the finished product is reached;

[0013] Performing acetone ultrasonic cleaning on the front cover plate that has been processed to the size required for the finished product to remove oil stains and impurities on the surface;

[0014] The cleaned front cover plate is dried to obtain a front cover plate product.

[0015] In a possible implementation, when the wall thickness of the front cover plate is less than a preset thickness range, a processing allowance of 2-3 mm is reserved on its outer surface.

[0016] In a possible implementation, the front cover plate product is fixed on a selective laser additive manufacturing device, and blades and a first support member for supporting the blades are printed layer by layer on its inner surface to obtain a first impeller semi-finished product, including:

[0017] Fixing the front cover plate product on the selective laser additive manufacturing device and adjusting it to a horizontal position, ensuring that its inner surface faces upward, and clamping the outer circular contour of the front cover plate product by the chuck of the selective laser additive manufacturing device;

[0018] The printing of the blade is sliced ​​by using a computer control system, and a printing path is planned; during this process, high-purity argon gas is introduced from the air inlet of the selective laser additive manufacturing equipment;

[0019] The laser processor of the selective laser additive manufacturing device is started to print the blades layer by layer on the inner surface of the front cover product according to the planned printing path; in this printing process, a powder spreading method is adopted, that is, after each layer is printed, the forming cylinder of the selective laser additive manufacturing device moves downward by a preset stroke, and the powder cylinder moves upward by the same stroke, so that the powder spreading brush can evenly spread a new layer of powder;

[0020] Among them, for the parts of the blades with an angle lower than 45°, the first support will be printed simultaneously to obtain a first impeller semi-finished product.

[0021] In a possible implementation, during the entire printing process, the dust purification system of the selective laser additive manufacturing equipment continues to work to collect and process excess powder.

[0022] In a possible implementation, when the powder brush lays each layer, the thickness of the powder layer is 0.2 mm.

[0023] In a possible implementation, the laser processor of the selective laser additive manufacturing device is started to print the blades layer by layer on the inner surface of the front cover plate product by selective melting according to the planned printing path.

[0024] In a possible implementation, the front cover plate product and the blade portion in contact with the first support member are polished until the surface roughness thereof is lower than Ra3.2.

[0025] In a possible implementation, in a post-processing stage, the surface of the third impeller semi-finished product from which the second support member has been removed is optimized by using an abrasive flow treatment technique to obtain a finished impeller product.

[0026] In a possible implementation, after abrasive flow treatment, the surface roughness of the impeller product at the flow channel inlet is lower than Ra1.6.

[0027] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects:

[0028] This application provides a method for preparing a closed impeller with a complex structure. First, this application adopts machining to prepare the front cover plate product. This production method is not only high in production efficiency and low in cost, and can meet the needs of large-scale production, but also has better surface quality of the machined front cover plate product. The raw material is forging as a whole, and its performance in all aspects is better than that of printing molding technology.

[0029] Secondly, this application makes full use of the high-precision layer-by-layer printing capability of the selective laser additive manufacturing technology. This technology not only successfully realizes the precise manufacturing of the blades and the first support, but also excels in processing complex structures that are difficult to achieve with traditional manufacturing methods, such as the twisted morphology and variable thickness characteristics of the blades. At the same time, by precisely controlling the printing process, it is ensured that the shape, size and position accuracy of the printed parts fully meet the design requirements. In addition, the first support effectively prevents the collapse and deformation of the blades during the printing process, thereby ensuring a high standard of printing quality.

[0030] Again, this application also uses selective laser additive manufacturing technology when manufacturing the rear cover. This technology achieves precise docking and integration between the rear cover and the blades, avoiding assembly errors and matching problems that may occur in traditional manufacturing methods. At the same time, in order to optimize the printing process and reduce costs, the rear cover is only added with a second support at the inlet of the impeller flow channel during the printing process, and other parts rely on the printed blades for support. This optimization not only reduces the number of second support members used, but also reduces the complexity and cost of the printing process.

[0031] In addition, compared with expensive five-axis machining equipment, the selective laser additive manufacturing technology used in this application significantly reduces the large amount of material waste caused by cutting, effectively saving processing time and cost. At the same time, compared with five-axis machining and traditional welding, the selective laser additive manufacturing technology avoids the problem of easy deformation due to excessive stress, and improves the stability and reliability of the product. This application also innovatively solves the problems of low efficiency, high cost and difficulty in removing support structures in the integrated printing process. Through step-by-step printing and precise control of the use of the first support member and the second support member, this application successfully realizes the efficient and low-cost manufacturing of closed impellers with complex structures, further enhancing the market competitiveness and application value of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic diagram of the structure of the finished impeller provided in the embodiment of the present application;

[0034] Figure 2 A schematic diagram of the structure of a selective laser additive manufacturing device provided in an embodiment of the present application;

[0035] Figure 3 A cross-sectional view of a front cover product provided in an embodiment of the present application;

[0036] Figure 4 A cross-sectional view of a semi-finished second impeller provided in an embodiment of the present application;

[0037] Figure 5 A cross-sectional view of a finished impeller provided in an embodiment of the present application;

[0038] Figure 6 A process flow chart of a method for preparing a closed impeller with a complex structure provided in an embodiment of the present application.

[0039] Icons: 1- finished impeller; 11- front cover product; 12- blades; 13- rear cover; 2- second impeller semi-finished product; 3- selected area laser additive manufacturing equipment; 31- laser processor; 32- forming cylinder; 33- powder cylinder; 34- air inlet; 35- powder brush; 36- chuck; 37- dust purification system; 4- computer control system; 5- third impeller semi-finished product. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0042] The present application embodiment provides a method for preparing a closed impeller with a complex structure, such as Figures 1 to 6 As shown, the method includes the following steps S1-S5:

[0043] S1: Prepare the front cover plate product 11 by machining.

[0044] Specifically, the present application adopts a CNC lathe to perform machining to prepare the front cover plate product 11, thereby improving production efficiency and meeting the needs of large-scale production.

[0045] S2: Fix the front cover plate product 11 on the selective laser additive manufacturing device 3, and print the blades 12 and the first support member for supporting the blades 12 on the inner surface layer by layer to obtain the first impeller semi-finished product.

[0046] It should be noted that the selective laser additive manufacturing technology, with its high-precision layer-by-layer printing capability, can ensure that the shape, size and position accuracy of the blade 12 and the first support member fully meet the design requirements. This technology is not only good at manufacturing complex structures that are difficult to achieve with traditional methods, such as the twisted shape and variable thickness characteristics of the blade 12, but can also easily cope with these challenges. During the printing process, the first support member plays an indispensable supporting role. It effectively prevents the blade 12 from collapsing and deforming due to its own weight or the thermal stress generated during the printing process, thereby ensuring a high standard of printing quality.

[0047] S3: removing the first support member from the first impeller semi-finished product, and grinding the front cover plate product 11 and the blades 12 contacted by the first support member to obtain the second impeller semi-finished product 2.

[0048] It should be noted that the present application can remove the traces and burrs left after the removal of the first support member and the minor unevenness that may be generated during the printing process through grinding treatment, so that the surface of the front cover plate product 11 and the blades 12 are smoother and flatter, and the appearance quality and touch of the second impeller semi-finished product 2 are improved. The grinding treatment of the surface of the blade 12 can optimize the shape and size of the flow channel of the second impeller semi-finished product 2 and reduce the resistance and eddy current in the flow channel of the second impeller semi-finished product 2.

[0049] S4: Fix the second impeller semi-finished product 2 to the selective laser additive manufacturing device 3, and print the rear cover plate 13 and the second support member located at the flow channel inlet of the second impeller semi-finished product 2 layer by layer on the side of the blade 12 away from the front cover plate product 11, to obtain the third impeller semi-finished product 5. Specifically, the present application adopts a layer-by-layer powder spreading method to print the rear cover plate 13 and the second support member.

[0050] It should be noted that the selective laser additive manufacturing technology can ensure the precise docking and integration between the rear cover plate 13 and the blades 12, avoiding assembly errors and matching problems that may occur in traditional manufacturing methods. During the additive manufacturing process, the rear cover plate 13 only adds a second support member at the inlet of the flow channel of the second impeller semi-finished product 2, and the other parts rely on the printed blades 12 for support.

[0051] S5: removing the second support member in the third impeller semi-finished product 5 and performing post-processing to obtain the impeller finished product 1.

[0052] Specifically, removing the second support member can eliminate the support marks that may be produced during the printing process, making the surface of the impeller product 1 smoother and neater. The post-processing step can further eliminate any minor surface defects and improve the appearance quality and overall performance of the impeller product 1.

[0053] Furthermore, the first support member and the second support member of the present application are removed by cutting, and then the cut parts are finely polished by a rotary file. This step not only ensures that the first support member and the second support member are completely and cleanly removed without any residue or impact on the final product; at the same time, the polishing process of the rotary file can also effectively smooth the cut surface, remove possible burrs and unevenness, and improve the surface quality and overall aesthetics of the product. In addition, this treatment method also helps to improve the durability and service life of the product, because the finely polished surface is smoother, reducing the possibility of friction and wear.

[0054] It should be noted that, firstly, the present application adopts machining to prepare the front cover plate product 11. This production method is not only highly efficient and low-cost, and can meet the needs of large-scale production, but also has better surface quality of the machined front cover plate product 11. The raw material is forged as a whole, and its performance in all aspects is better than that of printing molding technology.

[0055] Secondly, this application makes full use of the high-precision layer-by-layer printing capability of the selective laser additive manufacturing technology. This technology not only successfully realizes the precise manufacturing of the blade 12 and the first support, but also excels in processing complex structures that are difficult to achieve with traditional manufacturing methods, such as the twisted morphology and variable thickness characteristics of the blade 12. At the same time, by precisely controlling the printing process, it is ensured that the shape, size and position accuracy of the printed parts fully meet the design requirements. In addition, the first support effectively prevents the collapse and deformation of the blade 12 during the printing process, thereby ensuring a high standard of printing quality.

[0056] Again, the present application also uses the selective laser additive manufacturing technology when manufacturing the rear cover plate 13. This technology realizes the precise docking and integration between the rear cover plate 13 and the blades 12, avoiding the assembly errors and matching problems that may occur in the traditional manufacturing method. At the same time, in order to optimize the printing process and reduce costs, the rear cover plate 13 only adds a second support member at the inlet of the impeller flow channel during the printing process, and the other parts rely on the printed blades 12 for support. This optimization not only reduces the number of second support members used, but also reduces the complexity and cost of the printing process.

[0057] In addition, compared with expensive five-axis machining equipment, the selective laser additive manufacturing technology used in this application significantly reduces the large amount of material waste caused by cutting, effectively saving processing time and cost. At the same time, compared with five-axis machining and traditional welding, the selective laser additive manufacturing technology avoids the problem of easy deformation due to excessive stress, and improves the stability and reliability of the product. This application also innovatively solves the problems of low efficiency, high cost and difficulty in removing support structures in the integrated printing process. Through step-by-step printing and precise control of the use of the first support member and the second support member, this application successfully realizes the efficient and low-cost manufacturing of closed impellers with complex structures, further enhancing the market competitiveness and application value of the product.

[0058] In the embodiment of the present application, the front cover plate product 11 is prepared by machining, including the following steps S101-S103:

[0059] S101: The inner surface, outer surface and outer circle profile of the front cover are prepared by machining until the required size of the finished product is reached. This process not only ensures the geometric accuracy of the front cover product 11, but also lays a solid foundation for its subsequent precise matching with other components.

[0060] S102: The front cover plate that has been processed to the size required for the finished product is cleaned with acetone ultrasonic wave to remove oil stains and impurities on the surface.

[0061] It should be noted that the present application utilizes the strong solubility of acetone and the cavitation effect of ultrasound to effectively remove oil stains, metal debris and other tiny impurities attached to the surface of the front cover plate, ensuring that the surface cleanliness reaches a high standard.

[0062] S103: Drying the cleaned front cover to obtain a front cover product 11.

[0063] It should be noted that after cleaning, the front cover is dried to remove residual moisture and acetone to obtain a dry and clean front cover product 11. This step uses a suitable drying temperature and time to avoid thermal damage to the material of the front cover product 11 and ensure that the product can be quickly put into use.

[0064] In the embodiment of the present application, when the wall thickness of the front cover plate is less than the preset thickness range, a processing allowance of 2-3 mm is reserved on its outer surface. The processing allowance is reserved to ensure the subsequent processing accuracy and allow adjustment for slight deformation.

[0065] In the embodiment of the present application, the front cover plate product 11 is fixed on the selective laser additive manufacturing device 3, and the blades 12 and the first support member for supporting the blades 12 are printed layer by layer on the inner surface thereof to obtain the first impeller semi-finished product, including the following steps S201-S203:

[0066] S201: Fix the front cover plate product 11 on the selective laser additive manufacturing equipment 3 and adjust it to a horizontal position, ensure that its inner surface faces upward, and clamp the outer circular contour of the front cover plate product 11 by the chuck 36 of the selective laser additive manufacturing equipment 3.

[0067] It should be noted that adjusting the front cover plate product 11 to a horizontal position can ensure that the laser beam can act evenly and stably on the entire surface of the front cover plate product 11 during the subsequent laser additive manufacturing process. This can avoid processing errors caused by position tilt, thereby ensuring processing quality. At the same time, by clamping the outer circular contour of the front cover plate product 11 by the chuck 36 of the selective laser additive manufacturing equipment 3, it can ensure that the front cover plate product 11 maintains extremely high stability and precision during the processing. This clamping method effectively avoids processing errors caused by shaking or movement, and further improves the processing quality of the product.

[0068] S202: Slice the printed blade 12 using the computer control system 4 and plan a printing path. In this process, high-purity argon gas is introduced from the gas inlet 34 of the selective laser additive manufacturing device 3 .

[0069] Specifically, the purity of argon is 99.9%.

[0070] It should be noted that the present application utilizes a computer control system 4 to accurately slice the three-dimensional model of the blade 12 to generate a series of precise two-dimensional slices. Based on these two-dimensional slices, the computer control system 4 further plans the optimal printing path to ensure that the laser beam strictly follows the predetermined trajectory during the printing process, thereby improving the accuracy and efficiency of printing. At the same time, the use of high-purity argon as a protective gas effectively prevents oxidation reactions that may occur during laser additive manufacturing. Oxidation reactions will not only change the chemical composition and properties of the blade 12, but also lead to unstable printing quality. Therefore, the use of high-purity argon can ensure that the blade 12 maintains its original chemical composition and excellent performance during the printing process, thereby improving the overall printing quality.

[0071] S203: Start the laser processor 31 of the selective laser additive manufacturing device 3, and print the blades 12 layer by layer on the inner surface of the front cover plate product 11 according to the planned printing path. In this printing process, a powder spreading method is adopted, that is, after each layer is printed, the forming cylinder 32 of the selective laser additive manufacturing device 3 will move downward by a preset stroke, and the powder cylinder 33 will move upward by the same stroke, so that the powder spreading brush 35 can evenly spread a new layer of powder.

[0072] Among them, for the parts of the blade 12 where the angle is lower than 45°, the first support will be printed at the same time to obtain the first impeller semi-finished product.

[0073] It should be noted that the present application can ensure that each layer of the blade 12 is precisely formed in strict accordance with the predetermined design through a fine layer-by-layer printing method, thereby effectively avoiding the dimensional deviation and shape distortion problems that may occur in traditional processing methods. After each layer of printing is completed, the forming cylinder 32 and the powder cylinder 33 will move synchronously, and the powder brush 35 will evenly spread a new layer of powder. This ensures that the thickness of the powder layer of the next layer of printing remains consistent, thereby further improving the printing accuracy. In addition, for those fragile parts of the blade 12 with an angle lower than 45°, the first support member will be printed at the same time. The first support member can firmly support these parts and effectively prevent deformation or collapse caused by gravity or stress concentration during the printing process.

[0074] In the embodiment of the present application, during the entire printing process, the dust purification system 37 of the selective laser additive manufacturing equipment 3 works continuously to collect and process excess powder.

[0075] The dust purification system 37 can continuously collect and process excess powder, effectively avoiding the accumulation of powder in the printing area, not only keeping the printing environment clean, but also reducing the scattering and interference of powder on the laser beam, thereby ensuring that the laser beam can accurately act on the printing material and improving the printing accuracy.

[0076] In the embodiment of the present application, when the powder brush 35 lays each layer, the thickness of the powder layer is 0.2 mm.

[0077] It should be noted that setting the powder layer thickness to 0.2 mm can ensure that the laser beam can fully penetrate the powder layer, completely melt the powder and solidify it into the desired shape, thereby reducing material waste.

[0078] In the embodiment of the present application, the laser processor 31 of the selective laser additive manufacturing device 3 is started to print the blades 12 layer by layer on the inner surface of the front cover plate product 11 by selective melting according to the planned printing path.

[0079] The present application adopts the method of selective melting to print the blade 12 layer by layer by powder coating, which ensures that the blade 12 has high dimensional accuracy, low tissue stress and good tissue density, thereby avoiding the risk of impeller deformation that may be caused by traditional welding, and the problem that the weld interface is weak and cannot meet the high-speed and high-pressure working conditions.

[0080] In the embodiment of the present application, the front cover plate product 11 and the blade 12 that are in contact with the first support member are polished until the surface roughness thereof is lower than Ra3.2.

[0081] In the embodiment of the present application, in the post-processing stage, the surface of the third impeller semi-finished product 5 from which the second support member has been removed is optimized using abrasive flow treatment technology to obtain an impeller finished product 1.

[0082] After the abrasive flow treatment, a dense oxide film or work hardening layer is formed on the surface of the third impeller semi-finished product 5, which can significantly enhance the hardness and wear resistance of the surface, thereby extending the service life of the impeller finished product 1. At the same time, the smooth surface also helps to reduce the contact area between the corrosive medium and the surface of the impeller finished product 1, reduce the corrosion rate, and improve the corrosion resistance of the impeller finished product 1.

[0083] In the embodiment of the present application, after abrasive flow treatment, the surface roughness of the flow channel inlet of the impeller product 1 is lower than Ra1.6. With a surface roughness below Ra1.6, the surface quality of the impeller product 1 meets the high-quality manufacturing standard.

[0084] The present application effectively solves the problem that the support structure in the closed impeller manufactured by selective laser additive manufacturing is difficult to remove, and performs a grinding treatment on the surface roughness problem caused by removing the support structure. At the same time, the flow channel of the final impeller product 1 is subjected to abrasive flow treatment, thereby ensuring the efficient operation performance of the impeller product 1.

[0085] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0086] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A method for preparing a closed impeller with a complex structure, characterized in that: include: A front cover plate product (11) is prepared by machining, wherein the raw material of the front cover plate product (11) is a forging as a whole; The front cover plate product (11) is fixed on a selective laser additive manufacturing device (3), and blades (12) and a first support member for supporting the blades (12) are printed layer by layer on the inner surface thereof, so as to obtain a first impeller semi-finished product, comprising: The front cover plate product (11) is fixed on the selective laser additive manufacturing device (3) and adjusted to a horizontal position, ensuring that its inner surface faces upward, and the outer circular contour of the front cover plate product (11) is clamped by a chuck (36) of the selective laser additive manufacturing device (3); The printing of the blade (12) is sliced ​​using a computer control system (4) and a printing path is planned; during this process, high-purity argon gas is introduced from an air inlet (34) of the selective laser additive manufacturing device (3); The laser processor (31) of the selective laser additive manufacturing device (3) is started to print the blades (12) layer by layer on the inner surface of the front cover plate product (11) according to the planned printing path; during this printing process, a powder spreading method is adopted, that is, after each layer is printed, the forming cylinder (32) of the selective laser additive manufacturing device (3) moves downward by a preset stroke, and the powder cylinder (33) moves upward by the same stroke, so that the powder spreading brush (35) can evenly spread a new layer of powder; Wherein, for the portion of the blade (12) where the angle is less than 45°, the first support is printed simultaneously to obtain a first impeller semi-finished product; Removing the first support member from the first impeller semi-finished product, and grinding the portions of the front cover plate product (11) and the blades (12) contacted by the first support member, to obtain a second impeller semi-finished product (2); The second impeller semi-finished product (2) is fixed to the selective laser additive manufacturing device (3), and a rear cover plate (13) and a second support member located at the flow channel inlet of the second impeller semi-finished product (2) are printed layer by layer on the side of the blade (12) away from the front cover plate product (11), thereby obtaining a third impeller semi-finished product (5); Printing the rear cover plate (13) and the second support member in a layer-by-layer powder spreading manner; The second support member in the third impeller semi-finished product (5) is removed and post-processed to obtain an impeller finished product (1).

2. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: A front cover plate product (11) is prepared by machining, comprising: The inner surface, outer surface and outer circle profile of the front cover are prepared by machining until the required size of the finished product is reached; Performing acetone ultrasonic cleaning on the front cover plate that has been processed to the size required for the finished product to remove oil stains and impurities on the surface; The cleaned front cover plate is dried to obtain a front cover plate product (11).

3. The method for preparing a closed impeller with a complex structure according to claim 2, characterized in that: When the wall thickness of the front cover plate is less than a preset thickness range, a processing allowance of 2-3 mm is reserved on its outer surface.

4. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: During the entire printing process, the dust purification system (37) of the selective laser additive manufacturing device (3) continues to work to collect and process excess powder.

5. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: When the powder brush (35) lays each layer, the thickness of the powder layer is 0.2 mm.

6. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: The laser processor (31) of the selective laser additive manufacturing device (3) is started to print the blades (12) layer by layer on the inner surface of the front cover plate product (11) by selective melting according to the planned printing path.

7. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: The front cover plate product (11) and the blade (12) portions in contact with the first support member are polished until their surface roughness is lower than Ra3.

2.

8. The method for preparing a closed impeller with a complex structure according to claim 1, characterized in that: In the post-processing stage, the surface of the third impeller semi-finished product (5) from which the second support member has been removed is optimized using an abrasive flow treatment technique to obtain an impeller finished product (1).

9. The method for preparing a closed impeller with a complex structure according to claim 8, characterized in that: After abrasive flow treatment, the surface roughness of the flow channel inlet of the impeller product (1) is lower than Ra1.6.

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