Large-size motor shell inner fan electric arc additive and subtractive composite manufacturing method and application thereof

Abstract

This invention discloses a method for manufacturing a large-size motor housing internal fan using an arc-additive / subtractive composite process and its application. It belongs to the field of arc-additive manufacturing technology. The manufacturing method includes the following steps: Step 1, designing a large-size motor housing internal fan using an aerodynamic-structural coupling design model; Step 2, material selection: obtaining the chemical composition, mechanical property parameters, and additive layer size information of the arc-additive filament material according to the design requirements of the aerodynamic-structural coupling design model; Step 3, substrate pretreatment; Step 4, process control; Step 5, additive-subtractive composite manufacturing. The large-size motor housing internal fan obtained by this invention has a room temperature tensile strength ≥320MPa, yield strength ≥260MPa, elongation ≥12%, elastic modulus ≥71 GPa, density ≥99.9%, and fatigue life ≥10 at 12000 r / min. 8 Second-rate.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a large-size motor housing fan using an arc-additive / subtractive composite material and its application. It belongs to the field of arc-additive manufacturing technology. Background Technology

[0002] In modern industry, internal fans, as the core heat dissipation and cooling component of motor housings, are widely used in high-end equipment such as industrial motors with an outer diameter ≥500mm, operating speeds of 1500-12000r / min, and rated power of 30-280kW, as well as drive motors for new energy vehicles and traction motors for rail transit. Their structural performance and manufacturing precision directly determine the motor's operating efficiency, temperature rise control, and service life. Traditional manufacturing methods mainly rely on high-pressure die casting followed by machining, which suffers from numerous defects, cumbersome processes, limited performance, and low design freedom. Traditional additive manufacturing (SLM / EBM / ordinary arc) are all general-purpose additive methods without specific processes for internal fans of motors. They suffer from low efficiency, insufficient density, easy deformation in large sizes, poor dynamic balance accuracy, and poor stability of aluminum alloy forming, failing to address the specific technical challenges of internal fans for high-speed, high-power, and large-size motors.

[0003] Large-size fans (outer diameter ≥ 500mm): Additive molding is prone to warping and deformation, and coaxiality and dynamic balance are difficult to meet standards; High-speed operation (8000-12000 r / min): The blade fatigue strength is insufficient, and fatigue fracture is likely to occur; High-power, heavy-load operation: poor high-temperature mechanical properties, unable to meet long-term reliable operation requirements; Aluminum alloy laser additive manufacturing has high reflectivity, poor stability, and low yield. Near-net-shape forming relies on general interlayer milling, lacks a dedicated fan-based shape and property control solution, and is not innovative.

[0004] To address the specific technical challenges of internal fans in motors that cannot be solved by existing technologies, this invention provides a proprietary manufacturing solution that achieves significantly better performance than traditional die casting and general additive manufacturing. Summary of the Invention

[0005] This invention provides a dedicated electric arc additive and subtractive composite manufacturing method for fans inside motor housings. It abandons the general additive manufacturing approach and is specifically designed for large-size, high-speed, and high-power operating conditions, solving core problems such as deformation, precision, strength, fatigue, and heat dissipation efficiency matching that cannot be overcome by existing technologies.

[0006] Meanwhile, this invention provides an application of a method for manufacturing a large-size motor housing fan using an arc-additive / subtractive composite material.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The entire production process is designed based on product usage requirements and equipment characteristics, starting from model analysis and ending with precision machining, and arranged according to the process to ensure product quality.

[0008] A method for manufacturing a large-size motor housing internal fan using an arc-additive / subtractive composite material includes the following steps: Step 1, Model Design: A dedicated aerodynamic-structural coupling design model for the internal fan of the motor is adopted. The parameters of the dedicated aerodynamic-structural coupling design model are as follows: Wheel hub ratio formula: d / D = 0.35-0.5; d: Hub diameter (mm), which is the diameter of the center mounting part of the fan; D: Fan outer diameter (mm), which is the diameter of the outermost part of the fan blades.

[0009] Blade installation angle: β1=30°-55°, β2=10°-25°; β1: Leaf root installation angle (°), which is the angle between the leaf root and the plane of rotation; β2: Tip installation angle (°), which is the angle between the tip of the blade and the plane of rotation.

[0010] Distortion distribution law: θ(r) = θ0·(R / r) 1.58 θ(r): Blade twist angle (°) at radius r; θ0: Reference twist angle at the blade tip (°); R: Radius (mm) corresponding to the outer diameter D of the fan; r: The radius (mm) of the current calculation position, ranging from the hub radius to the fan outer radius.

[0011] Flow channel area constraint: A(r) = C•Q / (ρ•u•ΔP) 0.5 A(r): Flow area at radius r (mm²) 2 ); C: Flow channel correction factor, which is set to 1.12 for large-size fans in this invention; Q: Fan design airflow, i.e., fan rated airflow (m³ / s). 3 / s); ρ: Cooling air density (kg / m³) 3 The value is taken as 1.205 kg / m under standard working conditions. 3 ; u: Average airflow velocity (m / s) within the flow channel; ΔP: Allowable pressure loss in the flow channel (Pa).

[0012] Step 2, Model Building and Optimization Methods: The model construction and optimization process is as follows, which is a dedicated multi-field coupling optimization method: Step 1: Input operating parameters Simulation was performed using ANSYS Workbench (ANSYS Mechanical + Fluent + System Coupling) software, with the target motor's rated power P = 280kW, rated speed n = 12000r / min, and rated air volume Q = 12m³ / min as input. 3 Basic operating parameters include / s and allowable temperature rise ΔT=40K.

[0013] Step 2: Aerodynamic simulation iterative optimization CFD (Computational Fluid Dynamics) simulation (existing technology) is used. Twelve orthogonal simulation experiments were conducted for different hub ratios d / D, blade mounting angles β1 and β2, torsion coefficient (a dimensionless exponent controlling the degree of blade torsion), and aerodynamic efficiency (the ratio of the effective aerodynamic power output by the fan to the input power of the drive shaft). By comparing the results of orthogonal simulations, it was determined that the fan has the highest aerodynamic efficiency and the lowest pressure loss when the torsion coefficient is 1.58, the hub ratio is 0.35-0.5, the blade root installation angle is 30°-55°, and the blade tip installation angle is 10°-25°, thus obtaining the optimal aerodynamic parameters.

[0014] Step 3: Structural mechanics simulation verification: Import the optimized 3D model (twist coefficient of 1.58, hub ratio of 0.35-0.5, blade root installation angle of 30°-55°, blade tip installation angle of 10°-25°) into ANSYS Workbench software and perform mesh generation simultaneously. Input the material properties after additive manufacturing into the simulation software (ANSYS Workbench): tensile strength 320 MPa, yield strength 260 MPa, elastic modulus: 71 GPa, Poisson's ratio: 0.33, density: 2.75 g / cm³. 3 ); Set boundary conditions (simulating product installation status) and apply centrifugal load to simulate high-speed operation at 12000 r / min, while superimposing the maximum pressure load (125 Pa) obtained from the aerodynamic simulation in step 2 onto the blade surface.

[0015] Based on the torsion coefficient n=1.58, hub ratio d / D=0.45, inlet installation angle (i.e., blade root installation angle) 45°, outlet installation angle (i.e., blade tip installation angle) 20°, and the stagnation Bernoulli equation, the static pressure load (i.e., maximum pressure load) at the blade leading edge is calculated: When the fan is working, the airflow at the outer edge of the impeller impacts the stagnation point at the blade leading edge, causing flow stagnation. The local fluid velocity approaches 0, and the airflow pressure is completely converted into static pressure. According to the stagnation Bernoulli equation:

[0016] impeller outer edge linear velocity U 2:

[0017] The boundary conditions are a natural aspiration environment and an intake gauge pressure. P 0 = 0 Pa, the initial velocity of the incoming flow is approximately 0; ρ The density of the medium (air at normal temperature and pressure). n This refers to the fan's rated operating speed. R 2 represents the radius of gyration of the outer edge of the impeller.

[0018] By substituting the basic parameters into the formula, the theoretical calculated value of the static pressure at the leading edge of the blade (i.e., the maximum pressure load) of 125 Pa can be obtained.

[0019] The static structural analysis module [ANSYS Workbench Static Structural (ANSYS, USA)] was used to enable large deformation effects and solve for the equivalent stress distribution and total deformation of the blade.

[0020] The large deflection effect refers to the phenomenon where a structure undergoes sufficiently large displacement / deformation under load, resulting in a significant change in the structure's geometry, thereby altering the direction of the load and the structure's stiffness matrix.

[0021] In this invention, the large deformation effect is a deformation amount ≥ 5%.

[0022] The final results show that the maximum stress on the blade is 185 MPa, which is less than the material yield strength, and the deformation is 0.08 mm, which meets the dynamic balance requirements and verifies the reliability of the structure.

[0023] Step 4: Additive manufacturing process adaptation and adjustment: Based on the process characteristics of electric arc additive manufacturing, the optimized model was adapted and adjusted: for the thermal deformation problem of large-sized parts (≥500mm), the model was split into upper and lower sections, and the minimum wall thickness of the blades was constrained to ensure that the minimum wall thickness is ≥3mm, adapting to the stability of additive manufacturing, and finally obtaining exclusive model parameters.

[0024] Through 12 sets of orthogonal simulation experiments, the optimal torsion coefficient of 1.58, as well as the optimal range of hub ratio and mounting angle, were selected. The structural reliability of the parameters was verified through structural simulation. The partitioning and features of the model were adjusted through process adaptation, and finally, exclusive model parameters adapted to the internal fan of a large-size motor were obtained.

[0025] Combining the process characteristics of electric arc additive and subtractive manufacturing, and addressing the issue of large thermal deformation in large-sized parts, the model is specifically split into two parts: Partition 1 and Partition 2, i.e., Partition 1 is the hub circular structure of the fan inside the large-sized motor housing; Partition 2 is the remaining part of the fan inside the large-sized motor housing) are manufactured separately. At the same time, the split model is optimized for support and regularized for features to avoid unsupported overhanging structures or excessively small feature structures, thus ensuring the stability of the additive and subtractive composite manufacturing process.

[0026] Step 3, Material Selection: After model optimization, the chemical composition, mechanical properties, and additive layer dimensions of the wire material are obtained according to the design requirements of the internal fan model. The commonly used manufacturing material for the internal fan is aluminum alloy, and the additive manufacturing uses aluminum alloy wire specifically for arc additive manufacturing. The grade and manufacturer are as follows: ER4043 (AlSi5): Xingtai Yuguang Welding Materials Co., Ltd., Gongyi Siweite Welding Materials Co., Ltd., Hangzhou Xingguan New Materials Co., Ltd.; AlSi7Mg / AlSi10Mg series general-purpose welding wire (including 3D printing wire): Xingtai Yuguang Welding Materials Co., Ltd., Smic Welding Materials (Suzhou) Co., Ltd.; ER6061: Shandong Fuert Welding Materials Co., Ltd., Zhengzhou Chuanwang Welding Materials Co., Ltd.; ZL114A and ZL205A special wires: Xingtai Yuguang Welding Materials Co., Ltd., China Ordnance Industry No. 52 Research Institute The substrate is made of homologous aluminum alloy with a thickness of 20-40mm, and the difference in thermal expansion coefficient between the wire and the substrate is ≤5×10. -6 / K prevents the interface from cracking.

[0027] Step 4, Substrate pretreatment: The substrate pretreatment includes preheating and surface treatment. Specifically, the printing substrate is preheated to above 150°C and then polished using an angle grinder moved horizontally until the substrate is shiny. Step 5, Process Path Planning: Based on the principle of electric arc additive manufacturing, the additive filling path and the subtractive processing path are planned.

[0028] Fill path planning: Setting additive manufacturing process parameters and configuring them according to different path characteristics; The path characteristics of partition 1 are: wall path and circular offset fill path.

[0029] Among them, the annular offset filling path is a special filling path for the circular structure of the wheel hub: with the center of the wheel hub as the origin, the filling is carried out from the inside to the outside using an annular offset path, with an offset distance of 2-5mm for each layer, to ensure the uniformity of filling and reduce thermal deformation.

[0030] The additive manufacturing process parameters for the annular bias filling path are set as follows: additive voltage 20-25 V, additive current 160-200 A, additive speed 10-15 mm / s, and wire feeding speed 5-15 m / min. The parameters for the wall path additive manufacturing process are set as follows: additive voltage 15-20 V, additive current 120-160 A, additive speed 10-15 mm / s, and wire feeding speed 5-15 m / min.

[0031] The path characteristics of partition 2 are: wall path and offset path.

[0032] The offset path additive manufacturing process parameters are set as follows: additive voltage 20-25 V, additive current 160-200 A, additive speed 10-15 mm / s, and wire feeding speed 5-15 m / min. The parameters for the wall path additive manufacturing process are set as follows: additive voltage 15-20 V, additive current 120-160 A, additive speed 10-15 mm / s, and wire feeding speed 5-15 m / min.

[0033] Processing path planning: Machining in Zone 1: Rotation speed S = 5000-8000 r / min, Feed F = 3000-7000 mm / min. Partition 2 machining: Rotation speed S = 2000-8000 r / min, feed F = 4000-7000 mm / min.

[0034] Step Six, Process Control: High-purity argon is selected as the protective gas in additive manufacturing, with a gas flow rate set at 15-30 L / min. The interlayer temperature is controlled between 80-120℃ during the additive manufacturing process. Compressed air is used as a cooling method during the subtractive process, and the upper surface of the additive material is processed at intervals of 30-50mm to achieve interlayer shape control.

[0035] Step 7, Additive and Subtractive Material Composite Manufacturing: Section 1: Additive manufacturing direction is from bottom to top. For the first layer of additive manufacturing, use an additive voltage of 20-30V, an additive current of 180-220A, an additive speed of 10-15 mm / s, and a wire feed speed of 10-15 m / min for the outer wall. Then, use the set offset filling parameters and a circular offset path for filling additive manufacturing. Starting with the next layer, the wall layer uses an additive voltage of 15-20V, an additive current of 120-160A, an additive speed of 10-15 mm / s, and a wire feed speed of 5-15 m / min for additive manufacturing. The filling layer uses an additive voltage of 20-25V, an additive current of 160-200A, an additive speed of 10-15 mm / s, and a wire feed speed of 5-15 m / min. All other parameters and paths remain unchanged, and additive manufacturing is performed according to the predetermined process planning parameters.

[0036] Each time the additive material reaches a height of 30-50mm, the additive surface is machined. The subtractive process is planned as follows: rotation speed S=5000-8000r / min, feed F=3000-7000mm / min. After machining, the surface must be completely exposed to light to check for defects such as pores inside. At the same time, it ensures the flatness of the additive surface, reduces the occurrence of defects, corrects the warping of rotating parts, ensures dynamic balance reference, and facilitates subsequent quality control until the entire blank is completed.

[0037] After the additive manufacturing of the blank in section 1 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 1. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0038] Section 2: Additive fabrication direction is from bottom to top. For the first layer of additive fabrication, use an additive voltage of 20-30V, an additive current of 180-220A, an additive speed of 10-15 mm / s, and a wire feed speed of 10-15 m / min for the outer wall. Then, use the set offset filling parameters and a circular offset path for filling additive fabrication. Starting from the second layer, the wall is added using an additive voltage of 15-20V, an additive current of 120-160A, an additive speed of 10-15 mm / s, and a wire feed speed of 5-15 m / min. The filling is added using an additive voltage of 20-25V, an additive current of 160-200A, an additive speed of 10-15 mm / s, and a wire feed speed of 5-15 m / min. All other parameters and paths remain unchanged until the additive fabrication for Section 2 is complete.

[0039] After the additive manufacturing of the blank in section 2 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 2. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0040] After the partition printing is completed, partition 1 and partition 2 are connected together through the reserved installation holes. Finally, they are connected by manual TIG welding. The process uses DC positive polarity, φ2.4mm cerium tungsten electrode, and aluminum alloy welding wire of the same material as the additive manufacturing wire. The welding current is 80-120A, the argon gas protection flow rate is 8-12L / min, and the wire feed speed is 5-15m / min. After welding, the weld is inspected by X-ray and no defects are found. The whole body is then annealed to relieve stress.

[0041] The specific parameters for annealing are: The workpiece is heated to 300±10℃ and held for 2 hours, then cooled to room temperature in the furnace to eliminate additive manufacturing residual stress and welding stress, thus ensuring overall dimensional stability.

[0042] After completion, further surface processing is required to meet dimensional and usability requirements, which will not be elaborated upon here. X-ray inspection of the manufactured internal fan was performed to determine defect distribution. Results showed that the additive manufacturing method yielded an internal fan component with a density ≥99.9%, superior to casting (92%~96%), free of porosity and keyhole defects, meeting normal product usage standards. Simultaneously, the development cycle was shortened by more than 40%, and development costs were reduced by more than 50%.

[0043] Performance comparison data: Density: ≥99.9% for this invention; 95%–98.5% for SLM; 92%–96% for die casting; Tensile strength: ≥320MPa for this invention; ≤240MPa for die casting; ≤290MPa for SLM; Fatigue life (12000 r / min): ≥10 of this invention 8 Die casting ≤ 2×10 7 Times; SLM≤5×10 7 Second-rate; Improved heat dissipation efficiency: 18%–25% for this invention; ≤5% for die casting / general additive manufacturing; Near-net-shape allowance: ≤0.3mm for this invention; ≥1.0mm for traditional additive manufacturing; ≥1.5mm for die casting.

[0044] The present invention relates to a method for manufacturing a large-size motor housing fan using an arc-additive and subtractive composite manufacturing method.

[0045] The large-size motor housing fan of the present invention has an outer diameter ≥ 500 mm, an operating speed of 1500-12000 r / min, and a rated power of 30-280 kW.

[0046] The large-size motor housing fan of this invention has a room temperature tensile strength ≥320MPa, yield strength ≥260MPa, elongation ≥12%, elastic modulus ≥71 GPa, density ≥99.9%, and fatigue life ≥10 at 12000r / min. 8 Second-rate.

[0047] The application of the large-size motor housing fan in the motor according to the present invention.

[0048] Electric motors include high-end equipment such as industrial motors, new energy vehicle drive motors, and rail transit traction motors.

[0049] An industrial motor comprising a large-sized motor housing fan according to the present invention.

[0050] A new energy vehicle drive motor includes a large-sized motor housing fan as described in this invention.

[0051] A rail transit traction motor includes a large-sized motor housing fan according to the present invention.

[0052] Compared with the prior art, the present invention has the following significant advantages: The specific technical problem solved by this invention is: Large-sized (≥500mm) fans are prone to deformation due to their one-piece molding process, and their coaxiality / dynamic balance accuracy is insufficient. At high speeds (8000-12000 r / min), the blades have insufficient fatigue life and their strength does not meet the standards. Aluminum alloy laser additive manufacturing has high reflectivity, poor stability, and low yield. The near-net-shape forming accuracy is low, the subsequent processing volume is large, and it is impossible to achieve the optimal matching of the fan aerodynamic profile. Traditional processes cannot achieve optimal aerodynamic design for complex twisted blades and flow channels.

[0053] The outstanding advantages and significant effects of this invention are as follows: Density: The workpiece density is ≥99.9%, which is significantly better than SLM laser additive manufacturing (95%–98.5%). Mechanical properties: room temperature tensile strength ≥320MPa, yield strength ≥260MPa, elongation ≥12%; Fatigue life: ≥10 at 12000 r / min 8 The second time there was no fracture, which is more than 5 times that of die castings; Heat dissipation efficiency: Optimal aerodynamic blades improve the heat dissipation efficiency of the motor by 18%-25% and reduce the temperature rise by 12-18K; Near-net-shape forming: blade profile allowance ≤ 0.3mm, machining amount reduced by 70%, dynamic balance accuracy ≤ G1 level. Attached Figure Description

[0054] Figure 1 This is a flowchart of the present invention; Figure 2 This is a schematic diagram of the internal fan model of the present invention; Figure 3 This is a schematic diagram of the structure of partition 1 of the present invention; Figure 4 This is a schematic diagram of the structure of partition 2 of the present invention; Figure 5 This is a schematic diagram of the wall path and the ring-shaped offset fill path of partition 1 of the present invention; Figure 6 This is a schematic diagram of the wall path in partition 2 of the present invention; Figure 7 This is a schematic diagram of the bias path of partition 2 in this invention. Detailed Implementation

[0055] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0056] Example 1 like Figure 1 As shown, the entire production and manufacturing process of the product is designed according to the product usage requirements and equipment characteristics. From model analysis to finishing, the process is arranged according to the steps to ensure product quality.

[0057] A method for manufacturing a large-size motor housing internal fan using an arc-additive / subtractive composite material includes the following steps: Step 1, Model Design: A dedicated aerodynamic-structural coupling design model for the internal fan of the motor is adopted. The parameters of the dedicated aerodynamic-structural coupling design model are as follows: Wheel hub ratio formula: d / D = 0.35-0.5; d: Hub diameter (mm), which is the diameter of the center mounting part of the fan; D: Fan outer diameter (mm), which is the diameter of the outermost part of the fan blades.

[0058] Blade installation angle: β1=30°-55°, β2=10°-25°; β1: Leaf root installation angle (°), which is the angle between the leaf root and the plane of rotation; β2: Tip installation angle (°), which is the angle between the tip of the blade and the plane of rotation.

[0059] Distortion distribution law: θ(r) = θ0·(R / r) 1.58 θ(r): Blade twist angle (°) at radius r; θ0: Reference twist angle at the blade tip (°); R: Radius (mm) corresponding to the outer diameter D of the fan; r: The radius (mm) of the current calculation position, ranging from the hub radius to the fan outer radius.

[0060] Flow channel area constraint: A(r) = C•Q / (ρ•u•ΔP) 0.5 A(r): Flow area at radius r (mm²) 2 ); C: Flow channel correction factor, which is set to 1.12 for large-size fans in this invention; Q: Fan design airflow, i.e., fan rated airflow (m³ / s). 3 / s); ρ: Cooling air density (kg / m³) 3 The value is taken as 1.205 kg / m under standard working conditions. 3 ; u: Average airflow velocity (m / s) within the flow channel; ΔP: Allowable pressure loss in the flow channel (Pa).

[0061] Step 2, Model Building and Optimization Methods: The model construction and optimization process is as follows, which is a dedicated multi-field coupling optimization method: Step 1: Input operating parameters Simulation was performed using ANSYS Workbench (ANSYS Mechanical + Fluent + System Coupling) software, with the target motor's rated power P = 280kW, rated speed n = 12000r / min, and rated air volume Q = 12m³ / min as input. 3 Basic operating parameters include / s and allowable temperature rise ΔT=40K.

[0062] Step 2: Aerodynamic simulation iterative optimization CFD (Computational Fluid Dynamics) simulations were used (References 1-9). 1. Chen, Y.-C., Chen, C.-L., & Dong, Q. (2003). CFD Modeling for MotorFan System. Proceedings of the IEEE / ASME International Conference on Advanced Electronic Materials and Processes, 456-461.

[0063] 2. State Intellectual Property Office. (2013). A method for manufacturing an improved motor ventilation and heat dissipation structure based on fluid dynamics (Patent No.: CN201320225283.X).

[0064] 3.E-Cooling Engineering. (2026). CFD Cooling Calculations for Motors and Generators. Industry White Paper.

[0065] 4. Biesinger, T., & Schmidt, H. (2011). Evaluation of the MultipleReference Frame Approach for the Modeling of an Axial Cooling Fan. ASMETurbo Expo: Turbine Technical Conference and Exposition, GT2011-45237.

[0066] 5. Zhang, L., & Wang, H. (2017). Validation of an advanced fan model with multiple reference frame approach. Proceedings of the IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems(ITherm), 789-796.

[0067] 6. Li Gang, Wang Jun, Zhang Lei. (2023). Multi-factor orthogonal optimization design of fan considering impeller-volute clearance. Fluid Machinery, 51(6), 34-40.

[0068] 7. Liu, S., & Li, Y. (2020). Multiparameter and MultiobjectiveOptimization Design Based on Orthogonal Method for Mixed Flow Fan. Processes, 8(11), 1427.

[0069] 8. Wang Fujun, Zhang Zhaohui. (2018). Aerodynamic Design and Numerical Simulation of Axial Flow Fans. Machinery Industry Press.

[0070] 9. Kim, J., & Park, J. (2019). High-efficiency Axial Flow Fan Design by Combining Through-flow Modeling, Optimization Algorithm and CFDSimulation. Journal of Mechanical Science and Technology, 33(8), 3897-3906.

[0071] Twelve orthogonal simulation experiments were conducted for different hub ratios d / D, blade mounting angles β1 and β2, torsion coefficient (a dimensionless exponent controlling the degree of blade torsion), and aerodynamic efficiency (the ratio of the effective aerodynamic power output by the fan to the input power of the drive shaft). The parameters of the orthogonal simulation experiments are shown in Table 1 below. Table 1 Orthogonal simulation experiment parameters

[0072] By comparing the orthogonal simulation results in Table 1, it was determined that the fan has the highest aerodynamic efficiency and the lowest pressure loss when the torsion coefficient is 1.58, the hub ratio is 0.35-0.5, the blade root installation angle is 30°-55°, and the blade tip installation angle is 10°-25°, thus obtaining the optimal aerodynamic parameters.

[0073] Step 3: Structural mechanics simulation verification: Import the optimized 3D model (twist coefficient of 1.58, hub ratio of 0.35-0.5, blade root installation angle of 30°-55°, blade tip installation angle of 10°-25°) into ANSYS Workbench software and perform mesh generation simultaneously. Input the material properties after additive manufacturing into the simulation software (ANSYS Workbench): tensile strength 320 MPa, yield strength 260 MPa, elastic modulus: 71 GPa, Poisson's ratio: 0.33, density: 2.75 g / cm³. 3 ); Set boundary conditions (simulating product installation status) and apply centrifugal load to simulate high-speed operation at 12000 r / min, while superimposing the maximum pressure load (125 Pa) obtained from the aerodynamic simulation in step 2 onto the blade surface.

[0074] Based on the torsion coefficient n=1.58, hub ratio d / D=0.45, inlet installation angle (i.e., blade root installation angle) 45°, outlet installation angle (i.e., blade tip installation angle) 20°, and the stagnation Bernoulli equation, the static pressure load (i.e., maximum pressure load) at the blade leading edge is calculated: When the fan is working, the airflow at the outer edge of the impeller impacts the stagnation point at the blade leading edge, causing flow stagnation. The local fluid velocity approaches 0, and the airflow pressure is completely converted into static pressure. According to the stagnation Bernoulli equation:

[0075] impeller outer edge linear velocity U 2:

[0076] The boundary conditions are a natural aspiration environment and an intake gauge pressure. P 0 = 0 Pa, the initial velocity of the incoming flow is approximately 0; ρ The density of the medium (air at normal temperature and pressure). n This refers to the fan's rated operating speed. R 2 represents the radius of gyration of the outer edge of the impeller.

[0077] By substituting the basic parameters into the formula, the theoretical calculated value of the static pressure at the leading edge of the blade (i.e., the maximum pressure load) of 125 Pa can be obtained.

[0078] The static structural analysis module [ANSYS Workbench Static Structural (ANSYS, USA)] was used to enable large deformation effects and solve for the equivalent stress distribution and total deformation of the blade.

[0079] The large deflection effect refers to the phenomenon where a structure undergoes sufficiently large displacement / deformation under load, resulting in a significant change in the structure's geometry, thereby altering the direction of the load and the structure's stiffness matrix.

[0080] In this invention, the large deformation effect is a deformation amount ≥ 5%.

[0081] The final results show that the maximum stress on the blade is 185 MPa, which is less than the material yield strength, and the deformation is 0.08 mm, which meets the dynamic balance requirements and verifies the reliability of the structure.

[0082] Step 4: Additive manufacturing process adaptation and adjustment: Based on the process characteristics of electric arc additive manufacturing, the optimized model was adapted and adjusted: for the thermal deformation problem of large-sized parts (≥500mm), the model was split into upper and lower sections, and the minimum wall thickness of the blades was constrained to ensure that the minimum wall thickness is ≥3mm, adapting to the stability of additive manufacturing, and finally obtaining exclusive model parameters.

[0083] Through 12 sets of orthogonal simulation experiments, the optimal torsion coefficient of 1.58, as well as the optimal range of hub ratio and mounting angle, were selected. The structural reliability of the parameters was verified through structural simulation. The partitioning and features of the model were adjusted through process adaptation, and finally, exclusive model parameters adapted to the internal fan of a large-size motor were obtained.

[0084] Combining the characteristics of arc additive and subtractive manufacturing processes, and addressing the issue of large thermal deformation in large-sized parts, the model is specifically disassembled: [e.g., ...] Figure 2 The model shown is divided into two parts (such as...). Figure 3 Partition 1 shown and as Figure 4 The partition 2 shown is the hub circular structure of the fan inside the large-size motor housing (partition 1 is the fan hub circular structure inside the large-size motor housing; partition 2 is the remaining part of the fan inside the large-size motor housing). The partitioned models are manufactured separately. At the same time, the support optimization and feature regularization are performed on the disassembled models to avoid unsupported overhanging structures or overly small feature structures, so as to ensure the stability of the additive and subtractive composite manufacturing process.

[0085] Step 3, Material Selection: After model optimization, the chemical composition, mechanical properties, and additive layer dimensions of the wire material are obtained according to the design requirements of the internal fan model. The commonly used manufacturing material for the internal fan is aluminum alloy, and the additive manufacturing uses aluminum alloy wire specifically for arc additive manufacturing. The grade and manufacturer are as follows: ER4043 (AlSi5): Xingtai Yuguang Welding Materials Co., Ltd., Gongyi Siweite Welding Materials Co., Ltd., Hangzhou Xingguan New Materials Co., Ltd.; AlSi7Mg / AlSi10Mg series general-purpose welding wire (including 3D printing wire): Xingtai Yuguang Welding Materials Co., Ltd., Smic Welding Materials (Suzhou) Co., Ltd.; ER6061: Shandong Fuert Welding Materials Co., Ltd., Zhengzhou Chuanwang Welding Materials Co., Ltd.; ZL114A and ZL205A special wire materials: Xingtai Yuguang Welding Materials Co., Ltd., and the 52nd Research Institute of China Ordnance Industry.

[0086] The substrate is made of homologous aluminum alloy with a thickness of 20-40mm, and the difference in thermal expansion coefficient between the wire and the substrate is ≤5×10. -6 / K prevents the interface from cracking.

[0087] Step 4, Substrate pretreatment: The substrate pretreatment includes preheating and surface treatment. Specifically, the printing substrate is preheated to above 150°C and then polished using an angle grinder moved horizontally until the substrate is shiny. Step 5, Process Path Planning: Based on the principle of electric arc additive manufacturing, the additive filling path and the subtractive processing path are planned.

[0088] Fill path planning: Setting additive manufacturing process parameters and configuring them according to different path characteristics; The path characteristics of partition 1 are: wall paths and circular offset fill paths, such as... Figure 5 As shown.

[0089] Among them, the annular offset filling path is a special filling path for the circular structure of the wheel hub: with the center of the wheel hub as the origin, the filling is carried out from the inside to the outside using an annular offset path, with an offset distance of 2mm for each layer, to ensure the uniformity of filling and reduce thermal deformation.

[0090] The additive manufacturing process parameters for the annular bias filling path are set as follows: additive voltage 20 V, additive current 160 A, additive speed 10 mm / s, and wire feeding speed 5 m / min. The parameters for the wall path additive manufacturing process are set as follows: additive voltage 15 V, additive current 120 A, additive speed 10 mm / s, and wire feeding speed 5 m / min.

[0091] The path characteristics of partition 2 are as follows: wall path and offset path are as follows. Figure 6 and Figure 7 As shown.

[0092] The offset path additive manufacturing process parameters are set as follows: additive voltage 20 V, additive current 160 A, additive speed 10 mm / s, and wire feeding speed 5 m / min. The parameters for the wall path additive manufacturing process are set as follows: additive voltage 15 V, additive current 120 A, additive speed 10 mm / s, and wire feeding speed 5 m / min.

[0093] Processing path planning: Partition 1 machining: Rotation speed S = 5000 r / min, feed F = 3000 mm / min. Partition 2 machining: rotational speed S = 2000 r / min, feed F = 4000 mm / min.

[0094] Step Six, Process Control: High-purity argon is selected as the protective gas in additive manufacturing, with a gas flow rate set at 15L / min. The interlayer temperature is controlled at 80℃ during the additive manufacturing process. Compressed air is used as a cooling method during the subtractive process, and the upper surface of the additive material is processed at 30mm intervals to achieve interlayer shape control.

[0095] Step 7, Additive and Subtractive Material Composite Manufacturing: Section 1: Additive manufacturing direction is from bottom to top. For the first layer of additive manufacturing, an outer wall additive manufacturing process is performed using an additive voltage of 20 V, an additive current of 180 A, an additive speed of 10 mm / s, and a wire feed speed of 10 m / min. Then, filling additive manufacturing is performed using the set offset filling parameters and a circular offset path. Starting with the next layer, the wall is added using an additive voltage of 15 V, an additive current of 120 A, an additive speed of 10 mm / s, and a wire feed speed of 5 m / min. The filling process uses an additive voltage of 20 V, an additive current of 160 A, an additive speed of 10 mm / s, and a wire feed speed of 5 m / min. All other parameters and paths remain unchanged, and additive manufacturing is performed according to the predetermined process planning parameters.

[0096] Each time the additive material reaches a height of 30mm, the additive surface is machined. The subtractive process is planned as follows: rotation speed S=5000r / min, feed F=3000mm / min. After machining, the surface must be completely exposed to light. This is used to check for defects such as pores inside the material, while ensuring the flatness of the additive surface, reducing the occurrence of defects, correcting the warping of rotating parts, ensuring dynamic balance reference, and facilitating subsequent quality control until the entire blank is completed.

[0097] After the additive manufacturing of the blank in section 1 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 1. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0098] Section 2: Additive manufacturing direction is from bottom to top. For the first layer of additive manufacturing, an outer wall additive manufacturing process is performed using an additive voltage of 20 V, an additive current of 180 A, an additive speed of 10 mm / s, and a wire feed speed of 10 m / min. Then, filling additive manufacturing is performed using the set offset filling parameters and a circular offset path. Starting from the second layer, the wall is additive manufactured using an additive voltage of 15 V, an additive current of 120 A, an additive speed of 10 mm / s, and a wire feed speed of 5 m / min. The filling process uses an additive voltage of 20 V, an additive current of 160 A, an additive speed of 10 mm / s, and a wire feed speed of 5 m / min. All other parameters and paths remain unchanged until the additive manufacturing process in Section 2 is complete.

[0099] After the additive manufacturing of the blank in section 2 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 2. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0100] After the partition printing is completed, partition 1 and partition 2 are connected together through the reserved mounting holes. Finally, they are connected by manual TIG welding. The process uses DC positive polarity, 2.4mm cerium tungsten electrode, and aluminum alloy welding wire of the same material as the additive manufacturing wire. The welding current is 80A, the argon gas protection flow rate is 8L / min, and the wire feed speed is 5m / min. After welding, the weld is inspected by X-ray and no defects are found. The whole body is then annealed to relieve stress.

[0101] The specific parameters for annealing are: The workpiece is heated to 300℃ and held for 2 hours, then cooled to room temperature in the furnace to eliminate residual stress from additive manufacturing and welding stress, thus ensuring overall dimensional stability.

[0102] After completion, further surface processing is required to meet dimensional and usability requirements, which will not be elaborated upon here. X-ray inspection of the manufactured internal fan was performed to determine defect distribution. Results showed that the additive manufacturing method yielded an internal fan component with a density ≥99.9%, superior to casting (92%~96%), free of porosity and keyhole defects, meeting normal product usage standards. Simultaneously, the development cycle was shortened by more than 40%, and development costs were reduced by more than 50%.

[0103] Performance comparison data: Density: 99.9% in this example; 95%–98.5% in SLM; 92%–96% in die casting; Tensile strength: 320 MPa in this example; ≤240 MPa for die casting; ≤290 MPa for SLM; Fatigue life (12000 r / min): 10 in this example 8 Die casting ≤ 2×10 7 Times; SLM≤5×10 7 Second-rate; Improved heat dissipation efficiency: 18% in this embodiment; ≤5% for die casting / general additive manufacturing; Near-net-shape allowance: 0.3 mm in this example; ≥1.0 mm in traditional additive manufacturing; ≥1.5 mm in die casting.

[0104] This embodiment describes a large-size motor housing fan manufactured using an arc-additive / subtractive composite manufacturing method.

[0105] The large-size motor housing fan in this embodiment has an outer diameter ≥ 500mm, an operating speed of 1500-12000r / min, and a rated power of 30-280kW.

[0106] The large-size motor housing fan in this embodiment has a room temperature tensile strength of 320 MPa, a yield strength of 260 MPa, an elongation of 15%, an elastic modulus of 71 GPa, a density of 99.9%, and a fatigue life of 10 at 12000 r / min. 8 Second-rate.

[0107] This embodiment describes the application of a large-sized internal fan in a motor housing.

[0108] Electric motors include high-end equipment such as industrial motors, new energy vehicle drive motors, and rail transit traction motors.

[0109] An industrial motor, including a large-sized motor housing fan as described in this embodiment.

[0110] A new energy vehicle drive motor includes a large-sized fan inside the motor housing as described in this embodiment.

[0111] A rail transit traction motor includes a large-sized internal fan in the motor housing according to this embodiment. Example 2

[0112] The only difference between this embodiment and Embodiment 1 is that: The path characteristics of partition 1 are: wall path and circular offset fill path.

[0113] Among them, the annular offset filling path is a special filling path for the circular structure of the wheel hub: with the center of the wheel hub as the origin, the filling is carried out from the inside to the outside using an annular offset path, with an offset distance of 5mm for each layer, to ensure the uniformity of filling and reduce thermal deformation.

[0114] The additive manufacturing process parameters for the annular bias filling path are set as follows: additive voltage 25 V, additive current 200 A, additive speed 15 mm / s, wire feeding speed 15 m / min. The parameters for the wall path additive manufacturing process are set as follows: additive voltage 20 V, additive current 160 A, additive speed 15 mm / s, and wire feeding speed 15 m / min.

[0115] The path characteristics of partition 2 are: wall path and offset path.

[0116] The offset path additive manufacturing process parameters are set as follows: additive voltage 25 V, additive current 200 A, additive speed 15 mm / s, wire feeding speed 15 m / min; The parameters for the wall path additive manufacturing process are set as follows: additive voltage 20 V, additive current 160 A, additive speed 15 mm / s, and wire feeding speed 15 m / min.

[0117] Processing path planning: Partition 1 machining: Rotation speed S = 8000 r / min, feed F = 7000 mm / min. Partition 2 machining: rotational speed S = 8000 r / min, feed F = 7000 mm / min.

[0118] Step Six, Process Control: High-purity argon is selected as the protective gas in additive manufacturing, with a gas flow rate set at 30L / min. The interlayer temperature is controlled at 120℃ during the additive manufacturing process. Compressed air is used as a cooling method during the subtractive process, and the upper surface of the additive material is processed at 50mm intervals to achieve interlayer shape control.

[0119] Step 7, Additive and Subtractive Material Composite Manufacturing: Section 1: Additive manufacturing direction is from bottom to top. For the first layer of additive manufacturing, an outer wall additive manufacturing process is performed using an additive voltage of 30 V, an additive current of 220 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. Then, filling additive manufacturing is performed using the set offset filling parameters and a circular offset path. Starting with the next layer, the wall is added using an additive voltage of 20 V, an additive current of 160 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. The filling process uses an additive voltage of 25 V, an additive current of 200 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. All other parameters and paths remain unchanged, and additive manufacturing is performed according to the predetermined process planning parameters.

[0120] Each time the additive material reaches a height of 50mm, the additive surface is processed. The subtractive process is planned as follows: rotation speed S=8000r / min, feed F=7000mm / min. After processing, the surface must be completely exposed to light. This is used to check for defects such as pores inside the material, while ensuring the flatness of the additive surface, reducing the occurrence of defects, correcting the warping of rotating parts, ensuring dynamic balance reference, and facilitating subsequent quality control until the entire blank is additively processed.

[0121] After the additive manufacturing of the blank in section 1 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 1. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0122] Section 2: Additive manufacturing direction is from bottom to top. For the first layer of additive manufacturing, an outer wall additive manufacturing process is performed using an additive voltage of 30 V, an additive current of 220 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. Then, filling additive manufacturing is performed using the set offset filling parameters and a circular offset path. Starting from the second layer, the wall is additive manufactured using an additive voltage of 20 V, an additive current of 160 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. Filling additive manufacturing uses an additive voltage of 25 V, an additive current of 200 A, an additive speed of 15 mm / s, and a wire feed speed of 15 m / min. All other parameters and paths remain unchanged until the additive manufacturing process in Section 2 is complete.

[0123] After the additive manufacturing of the blank in section 2 is completed, the workpiece does not need to be disassembled. The milling spindle is switched to perform the machining of section 2. There is no need to repeat clamping, and the machining of the workpiece is completed in one go, reducing the error caused by clamping.

[0124] After the partition printing is completed, partition 1 and partition 2 are connected together through the reserved mounting holes. Finally, they are connected by manual TIG welding. The process uses DC positive polarity, 2.4mm cerium tungsten electrode, and aluminum alloy welding wire of the same material as the additive manufacturing wire. The welding current is 120A, the argon gas protection flow rate is 12L / min, and the wire feed speed is 15m / min. After welding, the weld is inspected by X-ray and no defects are found. The whole body is then annealed to relieve stress.

[0125] The specific parameters for annealing are: The workpiece is heated to 310℃ and held for 2 hours, then cooled to room temperature in the furnace to eliminate residual stress from additive manufacturing and welding stress, thus ensuring overall dimensional stability.

[0126] After completion, further surface processing is required to meet dimensional and usability requirements, which will not be elaborated upon here. X-ray inspection of the manufactured internal fan revealed defect distribution. Results showed that the additive manufacturing method achieved a density of 99.95%, superior to casting (92%~96%), with no porosity or keyhole defects, meeting normal product usage standards. Simultaneously, the development cycle was shortened by over 40%, and development costs were reduced by over 50%.

[0127] Performance comparison data: Density: 99.95% in this example; 95%–98.5% in SLM; 92%–96% in die casting; Tensile strength: 350 MPa in this example, yield strength 280 MPa, elongation 12%, elastic modulus 79 GPa; die casting ≤240 MPa; SLM ≤290 MPa; Fatigue life (12000 r / min): 10 in this example 9 Die casting ≤ 2×107 Times; SLM≤5×10 7 Second-rate; Improved heat dissipation efficiency: 25% in this embodiment; ≤5% for die casting / general additive manufacturing; Near-net-shape allowance: 0.25mm in this example; ≥1.0mm in traditional additive manufacturing; ≥1.5mm in die casting.

[0128] Example 3

[0129] The only difference between this embodiment and Embodiment 1 is that the annealing temperature is 290℃.

[0130] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0131] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and edibility purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0132] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for arc additive-subtractive manufacturing of a fan inside a large size motor housing, characterized in that, Includes the following steps: Step 1: Design a large-size fan inside the motor housing using an aerodynamic-structural coupling design model; Step 2, Material Selection: Obtain the arc additive manufacturing filament material based on the design requirements of the aerodynamic-structural coupling design model of the motor's internal fan; Step 3, substrate pretreatment: Substrate pretreatment includes preheating and surface treatment; Step 4, Process Control: High-purity argon is selected as the protective gas in additive manufacturing, with a gas flow rate set at 15-30 L / min. The interlayer temperature is controlled between 80-120℃ during the additive manufacturing process. Compressed air is selected as the cooling method during the subtractive process, and the upper surface of the additive is processed at intervals of 30-50mm to achieve interlayer shape control. Step 5, Additive and Subtractive Material Composite Manufacturing: Section 1: Additive manufacturing direction is from bottom to top: When performing the first layer of additive manufacturing, first use an additive voltage of 20-30 V, an additive current of 180-220 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 10-15 m / min to perform one layer of outer wall additive manufacturing. Then, use the set wall path and the ring-shaped offset filling path for filling additive manufacturing. Starting from the next layer, the wall is added using an additive voltage of 15-20 V, an additive current of 120-160 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 5-15 m / min. The filling is added using an additive voltage of 20-25 V, an additive current of 160-200 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 5-15 m / min. All other parameters and paths remain unchanged, and additive manufacturing is performed according to the established process planning parameters. After each addition reaches a height of 30-50mm, the addition plane is machined. The subtractive process is planned as follows: rotation speed S=5000-8000r / min, feed F=3000-7000mm / min. The surface is completely exposed after machining until the entire blank is added. After the additive manufacturing of the blank in section 1 is completed, switch to the milling spindle to perform machining in section 1; Section 2: Additive direction from bottom to top: When performing the first layer of additive manufacturing, first use an additive voltage of 20-30 V, an additive current of 180-220 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 10-15 m / min to perform one layer of outer wall additive manufacturing. Then, use the set wall filling path and offset path to perform filling additive manufacturing. Starting from the second layer, the wall uses an additive voltage of 15-20 V, an additive current of 120-160 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 5-15 m / min for additive manufacturing. The filling uses an additive voltage of 20-25 V, an additive current of 160-200 A, an additive speed of 10-15 mm / s, and a wire feeding speed of 5-15 m / min. The other parameters and paths remain unchanged until the additive manufacturing of Section 2 is completed. Each time the additive material reaches a height of 30-50mm, the additive surface is machined. The subtractive process is planned as follows: rotation speed S = 2000-8000r / min, feed F = 4000-7000mm / min. The surface is completely exposed after machining until the entire blank is finished with additive material. After the additive manufacturing of the blank in section 2 is completed, switch to the milling spindle to perform machining in section 2; After partitions 1 and 2 are printed, they are connected together using the pre-drilled mounting holes, and finally connected using the TIG connection process.

2. The production method according to claim 1, characterized by In step two, the arc additive manufacturing filament material is an aluminum alloy filament, and the substrate is a homologous aluminum alloy.

3. The production method according to claim 1, characterized by In step three, the substrate pretreatment method is as follows: preheat the substrate to above 150°C, and use an angle grinder to grind it horizontally until the substrate is bright.

4. The production method according to claim 1, characterized by In step five, the annular offset filling path of partition 1 is the filling path for the hub circular structure of the fan inside the large-size motor housing: with the center of the hub as the origin, the annular offset filling path is used to fill from the inside to the outside, and the offset distance of each layer is 2-5mm.

5. The production method according to claim 1, characterized by In step five, the TIG joining process uses DC positive polarity, with a φ2.4mm cerium tungsten electrode, and the filler wire is an aluminum alloy wire of the same material as the additive manufacturing wire. The welding current is 80-120A, the argon gas protection flow rate is 8-12L / min, and the wire feed speed is 5-15m / min. After welding, the weld is inspected by X-ray and found to be defect-free. The entire weld is then subjected to annealing to relieve stress.

6. The manufacturing method according to claim 5, characterized in that, The annealing process is as follows: heat the workpiece to 300±10℃, hold for 2 hours, and then cool it to room temperature in the furnace.

7. The manufacturing method according to claim 1, characterized in that, Step one, the design method of the aerodynamic-structural coupling design model of the fan inside the motor includes the following steps: Step 01, Model Design: The parameters of the aerodynamic-structural coupling design model are as follows: Wheel hub ratio formula: d / D = 0.35-0.5; d: Hub diameter, i.e., the diameter of the center mounting part of the fan, in mm; D: Fan outer diameter, which is the diameter of the outermost part of the fan blades, in mm; Blade installation angle: β1=30°-55°, β2=10°-25°; β1: Leaf root installation angle, which is the angle between the leaf root and the plane of rotation, in degrees; β2: Tip installation angle, which is the angle between the tip of the blade and the plane of rotation, in degrees; Twist distribution law: θ(r) = θ0·(R / r) 1.58 θ(r): Blade twist angle at radius r, in degrees; θ0: The reference twist angle at the blade tip, in degrees; R: The radius corresponding to the outer diameter D of the fan, in mm; r: The radius of the current calculation position, ranging from the hub radius to the fan outer radius, in mm; Flow passage area constraint: A(r) = C • Q / (p • u • ΔP) 0.5 A(r): flow passage flow area at radius r, unit: mm 2 ; C: Flow channel correction factor, with a value of 1.12; Q: The fan design air volume, i.e. the fan rated air volume, in m 3 / s; p: cooling air density, 1.205 kg / m3 under standard working conditions 3 ; u: Average airflow velocity within the flow channel, in m / s; ΔP: Allowable pressure loss in the flow channel, in Pa; Step 02, Aerodynamic-Structure Coupled Design Model Construction and Optimization Method: Step 1: Input operating parameters: Input the target motor's rated power P, rated speed n, rated air volume Q, and allowable temperature rise ΔT; Step 2: Aerodynamic simulation iterative optimization: The optimal aerodynamic parameters were determined to be: a torsion coefficient of 1.58, a hub ratio of 0.35-0.5, a blade root installation angle of 30°-55°, and a blade tip installation angle of 10°-25°. Step 3: Structural mechanics simulation verification.

8. The manufacturing method according to claim 1, characterized in that, Large-size motor housing fan with an outer diameter ≥500mm, operating speed 1500-12000r / min, rated power 30-280kW, and minimum blade wall thickness ≥3mm.

9. A large-size motor housing fan obtained by the manufacturing method according to any one of claims 1-8, characterized in that, Tensile strength at room temperature ≥320MPa, yield strength ≥260MPa, elongation ≥12%, elastic modulus ≥71 GPa, density ≥99.9%, fatigue life at 12000r / min ≥10 8 Second-rate.

10. The application of the large-size motor housing fan in a motor according to claim 9, characterized in that, Electric motors include industrial motors, new energy vehicle drive motors, and rail transit traction motors.

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