Machining method for generator input shaft of electric drive assembly

Abstract

The invention discloses a machining method for an input shaft of an electric drive assembly generator. The machining method comprises the following steps of first finish turning, second finish turning, gear hobbing, spline broaching, heat treatment, spline hard broaching, outer circle and end face grinding and gear grinding. In the step of hard pulling of the spline, the internal spline is subjected to hard pulling after being heated, the large diameter, the small diameter and the tooth side of the internal spline are subjected to hard pulling, and the precision of the internal spline subjected to heat treatment is corrected. In the step of grinding the outer circle and the end face, an internal spline of the input shaft of the generator is expanded, the end face and a center hole are positioned, and the outer circle and the end face of the input shaft of the generator are ground. In the gear grinding step, the internal spline of the input shaft of the generator is expanded, the end face is positioned, and gear grinding is conducted on the gear. Thermal deformation of the internal spline is corrected after heat treatment, then the internal spline is adopted as a standard for machining of subsequent procedures, the standard is unified, and it is guaranteed that the internal spline of the generator input shaft and the external spline of the generator rotor are well matched, torque is transmitted, a bearing operates stably, and operation stability of an electric drive assembly is guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of electric drive assembly shaft gear processing, and in particular relates to a method for processing an electric drive assembly generator input shaft. Background Art

[0002] In the existing electric drive assembly, shaft parts with internal spline structures are usually processed using two top holes as the reference. This method easily leads to poor concentricity of splines, outer circles, and gears. With the increase in the speed requirements of the electric drive assembly of new energy vehicles, extremely high requirements are placed on the mating internal and external splines. The traditional generator input shaft processing method uses center hole positioning to process the outer circle, without considering the concentricity of the generator input shaft outer circle, gears, and splines, resulting in the concentricity of the spline and the bearing outer circle being greater than 0.05mm, and it is difficult to ensure that the runout of the internal spline relative to the bearing outer circle of the two generator input shafts is within 0.05mm. At the same time, the internal splines of thin-walled parts are greatly deformed during the heat treatment process, causing the generator input shaft to move unbalancedly during rotation, poor dynamic balancing effect, and uneven bearing force, which leads to abnormal noise and knocking of the entire electric drive assembly, which is easy to cause NVH (noise, vibration and harshness) problems. Summary of the invention

[0003] In order to solve the problem that the internal spline of the existing generator input shaft is not concentric with the outer circle of the bearing, the purpose of the present invention is to provide a method for processing the input shaft of the electric drive assembly generator. The present invention corrects the thermal deformation of the internal spline after heat treatment, and then uses the internal spline as a reference for subsequent processing. The reference is unified to ensure that the internal spline of the generator input shaft and the external spline of the generator rotor are well matched, the torque is transmitted, the bearing runs smoothly, and the electric drive assembly runs smoothly.

[0004] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0005] A method for processing an input shaft of an electric drive assembly generator comprises the following steps: fine turning 1, fine turning 2, gear hobbing, spline drawing, heat treatment, hard drawing spline, grinding of outer circle and end face, and gear grinding; in the step of hard drawing spline, the inner spline is hard drawn after heat treatment, the size diameter and tooth side of the inner spline are hard drawn, and the accuracy of the inner spline after heat treatment is corrected; in the step of grinding the outer circle and end face, the inner spline of the generator input shaft is expanded, the end face and the top hole are positioned, and the outer circle and end face of the generator input shaft are ground; in the step of grinding the gear, the inner spline of the generator input shaft is expanded, the end face is positioned, and the gear is ground.

[0006] In the above scheme, through this series of steps, especially the correction of the internal spline accuracy by hard-drawing the spline, and the subsequent processing method based on the internal spline, the concentricity of the internal spline, outer circle and gear of the generator input shaft is ensured, and the running stability of the electric drive assembly is improved.

[0007] As a further optimization scheme of the present invention, in the finishing step 1, the first outer circle, the second outer circle, the first end face, the second end face and the top circle of the generator input shaft are finished.

[0008] In the above scheme, this step ensures the basic shape and dimensional accuracy of the generator input shaft, providing a good foundation for subsequent processing.

[0009] As a further optimization scheme of the present invention, in the fine turning step 2, the first outer circle and the second outer circle are clamped, the second end face is positioned, and the inner spline minor diameter is finely machined.

[0010] In the above scheme, the machining accuracy of the inner spline minor diameter is ensured by clamping and positioning, providing an accurate reference for the subsequent spline drawing and hard drawing steps.

[0011] As a further optimization scheme of the present invention, when the inner spline minor diameter is finely processed, it is necessary to ensure that the runout of the inner spline minor diameter based on the first outer circle and the second outer circle is within 0.015 mm.

[0012] In the above scheme, this precision requirement ensures the stability and accuracy of the inner spline diameter, helps to reduce thermal deformation during heat treatment and improve the concentricity of the final product.

[0013] As a further optimization scheme of the present invention, in the spline drawing step, the first end face is positioned and the internal spline is broached using an involute spline composite broach.

[0014] In the above scheme, the use of the involute spline composite broach ensures the shape and dimensional accuracy of the internal spline and provides a reliable benchmark for subsequent processing.

[0015] As a further optimization scheme of the present invention, the heat treatment steps include: pre-oxidation, convection heating, vacuum heating, pulse carburizing treatment, heating and heat preservation, quenching and cooling, and low-temperature tempering; wherein the temperature of the pre-oxidation treatment is 350-410°C, and the time of the pre-oxidation treatment is 60-120min; the temperature of the convection heating is 920-950°C, and the time of the convection heating is 20-40min; the temperature of the vacuum heating is 920-950°C, and the time of the vacuum heating is 40-70min; the number of pulse carburizing treatments is 5-9 times, and the pulse carburizing treatment is The pulse time is 30-180s, the temperature of pulse carburizing treatment is 920℃-1000℃, the time of pulse carburizing treatment is 3-14min, and the acetylene flow rate of pulse carburizing treatment is 2000-10000L / h; the temperature of heating and thermal insulation diffusion is 920-950℃, and the time of heating and thermal insulation diffusion is 30-120min; the time of quenching and cooling is 8-15min, and the pressure of quenching and cooling is 12-16bar; the temperature of low-temperature tempering is 150-300℃, and the time of low-temperature tempering is 120-180min.

[0016] Among them, pre-oxidation is to remove oil stains on the surface of parts, and to preliminarily heat the parts, saving heating energy in the carburizing process. Convection heating uses nitrogen circulation heating, the gas and parts have a large contact area, high heat exchange efficiency, shortened heating cycle, and vacuum heating can ensure that the parts are heated evenly without oxidation. Pulse multi-stage carburizing can use the concentration difference of acetylene in each carburizing stage to improve the utilization rate of acetylene infiltration. At the same time, the infiltration process is more controllable and uniform. The higher temperature of the heating process can improve the carburizing efficiency, and the lower temperature of the last stage of insulation can reduce the thermal stress of the cooling process and improve the accuracy of thermal deformation. Helium quenching has high cooling efficiency, can be recycled, and is safe and environmentally friendly. The low-temperature tempering process can eliminate the residual stress of the cooling process and improve the comprehensive performance of the parts.

[0017] As a further optimization scheme of the present invention, in the step of hard drawing the splines, the first end face is used for positioning, and the internal splines are subjected to post-heat hard drawing.

[0018] In the above scheme, the accuracy of the internal spline is further corrected through hot post-hard drawing processing, which ensures the stability of the internal spline and provides an accurate benchmark for subsequent processing.

[0019] As a further optimization scheme of the present invention, in the step of grinding the outer circle and end face, the internal spline of the generator input shaft is expanded with a spline expansion sleeve, the first end face and the right center hole are positioned, and the first outer circle, the second outer circle, the first end face and the second end face of the generator input shaft are ground.

[0020] In the above scheme, the grinding process is performed based on the internal spline, which ensures the accuracy and concentricity of the outer circle and the end face and improves the overall quality of the product.

[0021] As a further optimization scheme of the present invention, in the gear grinding step, the splines inside the generator input shaft are expanded with a spline expansion sleeve, and the first end face and the second end face are used for positioning, and the gear is ground.

[0022] In the above scheme, the gear grinding is performed based on the internal spline, which ensures the accuracy and concentricity of the gear and improves the meshing performance and transmission efficiency of the gear.

[0023] As a further optimization scheme of the present invention, the method for tightening the internal spline of the generator input shaft during the steps of grinding the outer circle and end face and grinding the teeth is as follows: after the robot grasps the generator input shaft, a camera is used on the material channel to take a picture to identify the position of the internal spline, which is transmitted to the machine tool through communication, and the machine tool spindle is rotated to a corresponding angle. The robot moves to the loading position for loading, and the internal spline of the generator input shaft cooperates with the spline expansion sleeve on the machine tool spindle fixture to realize the automatic clamping function of the spline expansion sleeve.

[0024] In the above scheme, this automated clamping method improves processing efficiency and accuracy, reduces errors and uncertainties in manual operations, and ensures product stability and consistency. At the same time, automated clamping also reduces the labor intensity of workers and improves production efficiency.

[0025] The present invention has the following advantages and beneficial effects:

[0026] The processing method of the present invention corrects the internal spline accuracy by hard drawing after heat treatment of the generator input shaft, and then uses the internal spline as a reference for subsequent external circle grinding and end face grinding processes, and gear grinding processes, unifying the processing reference and ensuring the concentricity of the internal spline, external circle, and gear. From the perspective of product function, it ensures the smooth meshing of the internal spline of the generator input shaft and the external spline of the generator rotor shaft, ensures the stable operation of the bearing and increases the service life, and greatly improves the NVH performance of the electric drive assembly.

[0027] The heat treatment steps mentioned in the present invention include multiple stages such as pre-oxidation, convection heating, and vacuum heating, which help control the heating and cooling process of the material, thereby reducing thermal deformation during the heat treatment process. This is crucial to ensure the concentricity of the inner spline, outer circle, and gear of the generator input shaft. Since the heat treatment improves the material properties and processing accuracy of the generator input shaft, the outer spline of the generator input shaft and the generator rotor shaft can be meshed more smoothly, reducing the generation of vibration and noise. At the same time, the stable operation and extended service life of the bearing also help to improve the NVH performance (noise, vibration, and harshness) of the electric drive assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the generator input shaft of the present invention.

[0029] Figure 2 Take a picture of the inner spline using a camera.

[0030] Figure numerals: 1 - generator input shaft; 2 - first outer circle; 3 - second outer circle; 4 - first end face; 5 - second end face; 6 - gear; 7 - internal spline. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary description and cannot be understood as a limitation on this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationship described in the drawings is only for exemplary description and cannot be understood as a limitation on this patent.

[0032] In order to ensure the concentricity of the internal spline, the external circle and the gear, the present invention provides a method for processing the input shaft of the electric drive assembly generator, which comprises the following steps: fine turning 1, fine turning 2, gear hobbing, spline drawing, heat treatment, hard spline drawing, external circle and end face grinding, and gear grinding.

[0033] In some examples, a method for processing an input shaft of an electric drive assembly generator includes the following specific steps:

[0034] 1. Finishing step 1:

[0035] The first outer circle 2, the second outer circle 3, the first end face 4, the second end face 5 and the tooth top circle of the generator input shaft are finely machined. This step ensures the basic shape and dimensional accuracy of the generator input shaft.

[0036] 2. Finishing 2 steps:

[0037] The second outer circle 3 is expanded with an expansion sleeve, the second end face 5 is positioned, the first outer circle 2 is clamped with an auxiliary center frame, and the minor diameter of the internal spline 7 is finely machined. During the machining process, it is necessary to ensure that the minor diameter of the internal spline 7 based on the first outer circle 2 and the second outer circle 3 is within 0.015mm. This step further improves the accuracy and stability of the internal spline 7.

[0038] 3. Gear Hobbing Steps:

[0039] The generator input shaft is clamped with two top holes, the expansion sleeve is used to expand the first outer circle 2, and the gear 6 of the generator input shaft is hobbed. This step ensures the shape and size accuracy of the gear 6.

[0040] 4. Steps for spline pulling:

[0041] With the first end face 4 positioned, an involute spline composite broach is used to broach the internal spline 7. This step forms the internal spline 7 structure of the generator input shaft.

[0042] 5. Heat treatment steps:

[0043] The specific process methods and parameters are shown in the following table:

[0044]

[0045] The hardness and strength of the generator input shaft material can be significantly improved through heat treatment, such as quenching and tempering. This is essential to improve the wear resistance, fatigue resistance and load-bearing capacity of the shaft, thereby extending the service life of the shaft. Heat treatment can change the microstructure of the material. For example, through pulse carburizing treatment, carbides can be formed in the material, which help to improve the hardness and wear resistance of the material. At the same time, heat treatment can also eliminate or reduce internal defects in the material, such as pores, inclusions, etc., thereby improving the overall performance of the material. After heat treatment, the hardness and strength of the material are improved, which makes it easier to obtain stable processing accuracy in subsequent processing (such as hard drawing splines, grinding outer circles and end faces, grinding teeth, etc.). At the same time, heat treatment can also reduce deformation and errors during processing, thereby improving the overall quality and stability of the product.

[0046] 6. Steps for hard pulling splines:

[0047] The internal spline 7 is positioned with the first end face 4, and then hard-drawn after heat treatment. During the hard-drawing process, the size diameter and tooth side of the internal spline 7 are corrected to eliminate the thermal deformation and error generated during the heat treatment process. This step ensures the accuracy and stability of the internal spline 7, and provides a reliable benchmark for subsequent processing.

[0048] 7. Steps for grinding the outer circle and end surface:

[0049] The spline expansion sleeve is used to expand the internal spline 7 of the generator input shaft, the first end face 4 and the right top hole are positioned, and the first outer circle 2, the second outer circle 3, the first end face 4 and the second end face 5 of the generator input shaft are ground. During the grinding process, the accuracy and surface quality of the outer circle and the end face must be ensured. This step further improves the accuracy and stability of the generator input shaft.

[0050] 8. Gear grinding steps:

[0051] The spline 7 in the generator input shaft is expanded with a spline expansion sleeve, and the first end face 4 and the second end face 5 are used for positioning, and the gear 6 is ground. During the grinding process, the shape, size and accuracy of the gear 6 must be ensured. This step ensures the meshing performance and transmission efficiency of the gear 6.

[0052] 9. Method for tightening the spline inside the generator input shaft:

[0053] After the manipulator grabs the generator input shaft, the camera on the material channel takes a photo to identify the position of the internal spline 7. The position is transmitted to the machine tool through communication, and the machine tool spindle rotates to the corresponding angle. The manipulator moves to the loading position for loading, and the internal spline 7 of the generator input shaft cooperates with the spline expansion sleeve on the machine tool spindle fixture to realize the automatic clamping function of the spline expansion sleeve. This step improves the processing efficiency and automation level.

[0054] In summary, after adopting the processing method of the present invention, the concentricity of the inner spline 7, the outer circle and the gear 6 of the generator input shaft is significantly improved. The smooth meshing of the inner spline 7 and the outer spline of the generator rotor shaft is guaranteed, and the stable operation and service life of the bearing are improved. At the same time, the NVH performance of the electric drive assembly is greatly improved. This invention is of great significance for improving the performance and reliability of the electric drive assembly of new energy vehicles.

[0055] According to the description and drawings of the present invention, those skilled in the art can easily use the method for processing the input shaft of an electric drive assembly generator of the present invention, and can produce the positive effects described in the present invention.

[0056] Unless otherwise specified, in the present invention, the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating orientation or positional relationships are based on the orientation or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or positional relationship in the present invention are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood in conjunction with the drawings and according to specific circumstances.

[0057] Unless otherwise clearly specified and limited, in the present invention, the terms "disposed", "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 directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for processing an input shaft of an electric drive assembly generator, characterized in that: The method comprises the following steps: fine turning 1, fine turning 2, gear hobbing, spline drawing, heat treatment, hard drawing spline, grinding of outer circle and end face, and gear grinding; in the step of hard drawing spline, the inner spline (7) is hard drawn after heat treatment, the size diameter and tooth side of the inner spline (7) are hard drawn, and the accuracy of the inner spline (7) after heat treatment is corrected; in the step of grinding the outer circle and end face, the inner spline (7) of the generator input shaft (1) is expanded, the end face and the top hole are positioned, and the outer circle and end face of the generator input shaft (1) are ground; in the step of grinding the gear, the inner spline (7) of the generator input shaft (1) is expanded, the end face is positioned, and the gear (6) is ground.

2. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the finishing step 1, the first outer circle (2), the second outer circle (3), the first end face (4), the second end face (5), and the tooth top circle of the generator input shaft (1) are finished.

3. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the fine turning step 2, the first outer circle (2) and the second outer circle (3) are clamped, the second end face (5) is positioned, and the minor diameter of the internal spline (7) is finely machined.

4. The method for processing the input shaft of the electric drive assembly generator according to claim 3, characterized in that: When fine machining is performed on the minor diameter of the internal spline (7), it is necessary to ensure that the runout of the minor diameter of the internal spline (7) based on the first outer circle (2) and the second outer circle (3) is within 0.015 mm.

5. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the spline drawing step, the first end face (4) is positioned, and an involute spline composite broach is used to perform broaching on the internal spline (7).

6. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: The heat treatment steps include: pre-oxidation, convection heating, vacuum heating, pulse carburizing, heating and heat preservation, quenching and cooling, and low-temperature tempering; wherein the temperature of the pre-oxidation treatment is 350-410°C, and the time of the pre-oxidation treatment is 60-120 minutes; the temperature of the convection heating is 920-950°C, and the time of the convection heating is 20-40 minutes; the temperature of the vacuum heating is 920-950°C, and the time of the vacuum heating is 40-70 minutes; the number of pulse carburizing treatments is 5-9 times, and the pulse time of the pulse carburizing treatment is 3 0~180s, the temperature of pulse carburizing treatment is 920℃~1000℃, the time of pulse carburizing treatment is 3~14min, and the acetylene flow rate of pulse carburizing treatment is 2000~10000L / h; the temperature of heating and thermal insulation diffusion is 920~950℃, and the time of heating and thermal insulation diffusion is 30~120min; the time of quenching and cooling is 8~15min, and the pressure of quenching and cooling is 12~16bar; the temperature of low-temperature tempering is 150~300℃, and the time of low-temperature tempering is 120~180min.

7. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the spline hard drawing step, the first end face (4) is used for positioning, and the internal spline (7) is subjected to a post-heat hard drawing process.

8. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the step of grinding the outer circle and end face, the internal spline (7) of the generator input shaft (1) is expanded with a spline expansion sleeve, the first end face (4) and the right center hole are positioned, and the first outer circle (2), the second outer circle (3), the first end face (4) and the second end face (5) of the generator input shaft (1) are ground.

9. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: In the gear grinding step, the internal spline (7) of the generator input shaft (1) is expanded with a spline expansion sleeve, the first end face (4) and the second end face (5) are used for positioning, and the gear (6) is subjected to gear grinding.

10. The method for processing the input shaft of the electric drive assembly generator according to claim 1, characterized in that: The method for tightening the internal spline (7) of the generator input shaft (1) during the steps of grinding the outer circle and end face and grinding the gear is as follows: after the manipulator grasps the generator input shaft (1), a camera is used on the material channel to take a picture to identify the position of the internal spline (7), which is transmitted to the machine tool by communication, the machine tool spindle is rotated to a corresponding angle, the manipulator moves to the loading position for loading, and the internal spline (7) of the generator input shaft (1) cooperates with the spline expansion sleeve on the machine tool spindle fixture to realize the automatic clamping function of the spline expansion sleeve.

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