Method for controlling eccentric deformation of a transmission shaft part during cold working

Abstract

The present application belongs to the field of aviation machining process, and relates to a method for controlling eccentric deformation of transmission shaft parts through a cold machining process. The method comprises the following steps: adjusting the axial size and radial size allowance of the part before heat treatment, at least ensuring the part position required by the penetration layer, and giving the allowance according to the penetration layer calculation size; adjusting the thin-wall shaft diameter position and the web position of the part structure before heat treatment; establishing the machining datum after heat treatment; designing the post-heat process, reasonably arranging the post-heat machining sequence, determining the alignment method and checking the run-out position, giving the alignment value, and refining the machining steps and allowance; determining the control method of the eccentricity of the part by post-heat turning machining; balancing the process control, adding a pre-balancing process, and adjusting the key position of the part before weight removal and the unbalance amount through local tolerance change.

Description

Technical Field

[0001] This invention belongs to the field of aerospace processing technology and relates to a method for controlling eccentric deformation of transmission shaft parts through cold working process. Background Technology

[0002] The main processing problem encountered with drive shaft parts is deformation after heat treatment, which leads to a series of processing issues due to severe deformation. Secondary problems mainly affect areas where heat treatment deformation makes them unprocessable, resulting in uneven diffusion layers, excessive initial imbalance, and surface cracks. It is necessary to clarify the processing problems of these parts and develop an overall processing plan to mitigate or avoid these problems as much as possible.

[0003] Whether the eccentric deformation control of the drive shaft meets the requirements directly affects the performance of the verification machine. Proper control can improve its working vibration amplitude, extend the service life of the machine body, and greatly benefit the reduction of fatigue of various components and the improvement of work efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method for controlling post-heat deformation of drive shafts with a length-to-diameter ratio greater than 2 and containing gears or splines. This method aims to achieve an overall part eccentricity of no more than 0.05 mm and a reference shaft runout of no more than 0.01 mm after heating. The initial imbalance of the part is controlled at level 6.3, achieving a final balance reduction from 100% to 20% of the deviation, and reducing the deviation in surface penetration thickness and grinding roughness from 40% to 0%. The causes of part deformation affecting drive shaft performance and efficiency are analyzed, and reasonable solutions are developed based on the technical problems encountered during processing, thereby optimizing and improving drive shaft performance.

[0005] The technical solution of this invention is:

[0006] This invention provides a method for controlling eccentric deformation during cold working of transmission shaft parts, comprising:

[0007] Step 1: Adjust the axial and radial dimension allowances of the parts before heat treatment, ensuring that at least the parts requiring diffusion layering have the allowance calculated according to the diffusion layer dimensions.

[0008] Step 2: Adjust the thin-walled shaft diameter section and spoke section of the part structure before heat treatment to reduce the complexity of the pre-heat treatment structure, increase the support force, and prevent the spokes from deforming under stress.

[0009] Step 3: Establish machining datum after heat treatment: In order to prevent the dimensional deviation of the diffusion layer caused by the eccentricity of the parts and the inability to machine to the final state in some areas, a joint datum should be established after heat treatment to evenly distribute the machining allowance of the parts and avoid the above situation caused by severe deformation in a certain position.

[0010] Step 4: Design post-heat treatment processes, rationally arrange post-heat treatment machining processes, determine alignment methods and check runout locations, give alignment values, and refine machining steps and allowances;

[0011] Step 5: Determine the method for controlling the eccentricity of the part during post-heat turning, and provide specific turning schemes for the outer shape and inner cavity of the long shaft;

[0012] Step 6: Determine the method for controlling the eccentricity of the parts in the post-heat external grinding process, and formulate a method for controlling vibration marks for the cavity structure to improve surface roughness;

[0013] Step 7: Determine the method for controlling the eccentricity of the part in the post-heat grinding process, and customize the grinding allowance and penetration depth control scheme according to the tooth deformation.

[0014] Step 8: Balance process control. Add a pre-balancing process and adjust the key positions and imbalance of parts before balancing by changing local tolerances.

[0015] Adjusting the axial allowance includes:

[0016] Based on previous deformation patterns, the allowance for the total shaft diameter before heat treatment should be no less than 1 mm on each side, and no less than 0.5 mm at local locations on the shaft diameter. If a spoke structure exists, the allowance on each side of both ends of the spoke should be no less than 0.7 mm. For areas requiring a diffusion layer, allowances should be given according to the calculated dimensions of the diffusion layer.

[0017] Adjusting the radial allowance includes:

[0018] For non-carburized surfaces that are easy to machine, the allowance on one side shall not be less than 1 mm, and the allowance on thin-walled surfaces may be increased to 2 mm; for non-carburized surfaces that are difficult to machine, the allowance on one side shall not be less than 0.5 mm; for parts that cannot be machined, they may be pre-machined to the final state.

[0019] Adjusting the radial allowance includes:

[0020] For non-carburized surfaces and easily machinable parts, adjust the single-sided allowance to be no less than 1mm, and increase the allowance to 2mm for thin-walled parts.

[0021] For non-carburized surfaces and difficult-to-machine areas, adjust the single-sided allowance to be no less than 0.5mm;

[0022] Unprocessable parts are pre-processed to their final state before heating.

[0023] Adjustments were made to the thin-walled shaft diameter section and spoke section of the part structure before heat treatment, including:

[0024] For thin-walled shaft diameter sections, reduce complex pre-heating structures and replace them with through-rod structures;

[0025] For the spoke section, a reinforced rounded base is added with a radius one-third of the spoke's radial length to enhance support.

[0026] If the part has a spoke hole structure, the bottom hole is machined out before heat treatment to allow the heat treatment quenching oil to flow and prevent the spoke from deforming under stress.

[0027] Before heat treatment, the dimensional arrangement is based on the post-heat treatment reference surface as the starting surface to reduce the risk of insufficient machining allowance caused by dimensional chain movement due to heat treatment deformation.

[0028] Establish machining standards after heat treatment, including:

[0029] After heat treatment, align the overall axis of the part to reduce local deviations: use a three-jaw chuck to clamp one side of the shaft diameter of the part, and clamp the shaft end ring with 5mm; check the runout of the left reference shaft, align the runout of the other end, and repeatedly adjust the shaft diameter with larger runout until the runout of the reference shafts at both ends is within 0.015.

[0030] Check the pitch circle runout of the teeth and splines of the part. Use a four-jaw chuck to hold a three-jaw chuck and adjust the runout of the part radially to ensure that the pitch circle runout is within 0.05.

[0031] Based on the processing allowance and penetration depth of each part, fine-tune using the same method as the previous step to ensure that the runout of each part meets the requirements.

[0032] Machining the center hole and grinding the datum surface, using the datum surface for clamping and alignment in subsequent processes: Before and after finishing processes such as precision turning, grinding the center hole, and precision grinding, check the runout of the part. If the runout is large in a local area, correct the datum using the above alignment method.

[0033] The machining process includes: sequentially performing internal and external shaping, milling, grinding the center hole, external grinding, internal grinding, and gear grinding.

[0034] Determine the method for controlling the eccentricity of parts during the post-heat grinding process, and develop a method for controlling vibration marks based on the cavity structure to improve surface roughness, including:

[0035] Choosing two datums with a relatively large axial distance—the joint datum between the double-sided bearing shaft and the gear major diameter—as the overall axis of the part is more reasonable for alignment after hot machining. After establishing the axis, check all carburized parts of the part before machining, and determine whether the dimensional requirements are met based on the grinding allowance at each location. After hot machining, grind the centers to check the two newly selected locations, and then grind the datum shaft. During subsequent machining, align the gear tooth major diameter and the two side bearing shafts, and check the runout of the datum shaft in the middle. Before finishing the journal, align the datum, and at the same time check that the runout of the gear teeth and spline pitch circle is within 0.02, and check that the runout of the journal to be ground is within 0.01.

[0036] The original input gear was clamped using a substitute tooling. The substitute tooling was a long rod structure with annular outer centers at both ends that mate with the bevel gear center holes, and external nuts were used for locking. Before machining, the center holes at both ends of the substitute rod were tightened, and the outer diameter reference was aligned for machining. The cylindricity was improved from 0.02 to 0.005, and the radial clamping deformation was reduced by about 0.01.

[0037] The advantages of this invention are:

[0038] The present invention provides a method for controlling eccentric deformation during cold working of transmission shaft parts, comprising: Step 1, adjusting the dimensions of the part before heat treatment, and adjusting the axial and radial dimension allowances; Step 2, adjusting the structure of the part before heat treatment, adjusting the thin-walled shaft diameter and spoke areas; Step 3, establishing the machining datum after heat treatment; Step 4, designing the post-heat treatment machining process, rationally arranging the post-heat treatment machining processes, determining the alignment method and checking the runout position, giving the alignment value, and refining the machining steps and allowances; Step 5, determining the method for controlling the eccentricity of the part during post-heat turning, and providing specific turning schemes for the external shape and internal cavity of the long shaft; Step 6, determining the method for controlling the eccentricity of the part during post-heat external grinding, and developing a method for controlling vibration marks and improving surface roughness for the cavity structure; Step 7, determining the method for controlling the eccentricity of the part during post-heat gear grinding, and customizing grinding allowance and penetration depth control schemes for tooth deformation; Step 8, controlling the balancing process, adding a pre-balancing process, and adjusting the key positions and unbalance of the part before balancing and weight removal through local tolerance changes. The new method solves the machining problems encountered after heat treatment of shaft parts, and improves the machining process and steps. It meets the journal dimensional tolerance of ±0.006, journal total runout of 0.015, and journal cylindricity of 0.003. It meets the Class 5 accuracy requirements for the gear teeth and splines of the transmission shaft, ensuring the uniformity of gear parameters and carburized layer. It innovatively studies a machining compensation method for easily deformable long shafts and a multi-gear tooth alignment machining method, achieving zero deviation in the diameter deformation control of long shafts. It also improves the wall thickness control method for slender shafts, making the part wall thickness more uniform, reducing the initial balance amount, and improving the stability of the part during operation. Attached Figure Description

[0039] Figure 1 Comparison of alignment before and after the grinding of the center hole process;

[0040] Figure 2 A schematic diagram showing the eccentricity after changing the alignment and inspection method;

[0041] Figure 3 Schematic diagram of a transmission shaft being machined using auxiliary support for a lathe;

[0042] Figure 4 Schematic diagram of tie rod clamping on an external cylindrical grinding machine;

[0043] Figure 5 Schematic diagram of gear grinding and clamping of drive shaft. Detailed Implementation

[0044] Reference Figures 1-5 The present invention provides a method for controlling eccentric deformation during cold working of transmission shaft parts, comprising:

[0045] Step 1: Adjust the dimensions and structure of the parts before heat treatment

[0046] Axial allowance adjustment: Based on the previous deformation patterns, the allowance for the total shaft diameter before heat treatment should be no less than 1mm on each side, and the allowance at local locations on the shaft diameter should be no less than 0.5mm. If there is a spoke structure, the allowance on each side of both ends of the spokes should be no less than 0.7mm. For parts requiring carburization, the allowance should be given according to the calculated dimensions of the carburization layer. Radial allowance adjustment: For non-carburized surfaces and easily machinable parts (such as outer diameters and large-diameter inner holes), the allowance on each side should be no less than 1mm, and the allowance for thin-walled parts can be increased to 2mm; for non-carburized surfaces and difficult-to-machinable parts (such as inner hole grooves), the allowance on each side should be no less than 0.5mm; parts that cannot be machinable can be pre-machined to the final state (this should be avoided if possible).

[0047] Step 2: Adjust the structure of the parts before heat treatment, and make adjustments to the thin-walled shaft diameter section and the spoke section.

[0048] Structural adjustments: For thin-walled shaft diameter sections, minimize pre-heat treatment complexity and replace with a through-rod structure. For spoke sections, add a root reinforcement rounded end with a radius one-third of the spoke's radial length to enhance support. If the final part has spoke hole structures, it is recommended to machine the bottom holes before heat treatment to allow for the flow of heat treatment quenching oil and prevent spoke deformation under stress.

[0049] Before heat treatment, the dimensions should be arranged with the post-heat treatment reference surface as the starting surface as much as possible. This can reduce the risk of insufficient machining allowance caused by dimensional chain movement due to heat treatment deformation.

[0050] Step 3: Establishing the machining datum after heat treatment.

[0051] (1) After heat treatment, align the overall axis of the part to reduce local deviations. Use a three-jaw chuck to clamp one side of the shaft diameter of the part, with a 5mm clamping ring at the shaft end. To prevent damage, copper jaws or copper pads can be used for clamping. Check the runout of the left reference shaft, align the runout of the other end, and repeatedly adjust the shaft diameter with the larger runout until the runout of the reference shafts at both ends is within 0.015. The alignment amounts for each process after heat treatment are shown in Table 1.

[0052] Table 1

[0053]

[0054] (2) Check the pitch circle runout of the teeth and splines of the part. Use a four-jaw chuck to hold a three-jaw chuck and adjust the runout of the part radially to ensure that the pitch circle runout is within 0.05. Note that during the adjustment process, the axis of the part should be kept parallel to the machining plane of the machine tool and there should be no tilt adjustment.

[0055] (3) Combine the processing allowance and penetration depth of each part, and make fine adjustments using the same method as in the second step to ensure that the vibration of each part meets the requirements.

[0056] (4) Machining the center hole and grinding the datum surface, using the datum surface for clamping and alignment in subsequent processes. Before and after finishing the finishing turning, grinding the center hole and finishing grinding processes, it is necessary to check the runout of the part. If the runout is large in a local area, the datum needs to be corrected by the above alignment method.

[0057] Step 4: Design post-heat treatment processes, rationally arrange post-heat treatment machining processes, determine alignment methods and check runout locations, set alignment values, and refine machining steps and allowances.

[0058] (1) After the datum machining is completed after heat treatment, all machining processes such as turning the inner and outer shapes, milling, grinding the center hole, external grinding, internal grinding, and gear grinding should be carried out in sequence.

[0059] (2) After heat treatment, improve the step of aligning the reference surface before machining and increase the requirement for checking the runout of the machining part to the reference surface after machining.

[0060] (3) Post-heat treatment dimension arrangement: For parts with significant heat treatment deformation, such as the ends of the shaft diameter and spokes, even with large tolerances, dimensions should be arranged directly related to the datum plane to reduce the risk of exceeding tolerances due to excessive dimensional chain overlap. Furthermore, to prevent missing the optimal correction process for part deformation, post-heat treatment processes (except for dimensions with special requirements) should not deviate from the datum plane and establish axial dimensions separately.

[0061] Step 5: Determine the method for controlling the eccentricity of the part during post-heat turning, and provide specific turning schemes for the outer shape and inner cavity of the long shaft.

[0062] Turning of the inner cavity after heating is the key part turning process. The quality of the inner cavity turning directly affects the uniformity of the wall thickness and the overall eccentricity of the part.

[0063] (1) To counteract the effect of heat treatment deformation on the reference shaft, a process of grinding the center and the reference shaft is added before finish turning. The ground center hole is used to clamp the part during finish turning. The ground reference shaft is used to check the runout of the part before finish turning. All carburized surfaces and parts with wall thickness that are prone to exceeding tolerance are aligned before grinding the reference shaft to ensure a runout value of 0.03. The turning process establishes a relationship between the reference journal and the overall axis of the part to ensure that the small end of the finish turning is eccentric to the axis of the part. Due to the small allowance, the finish turning process has the conditions for CNC turning with two center holders. After turning the small end, the part does not need to be unloaded, and thread turning is performed directly.

[0064] (2) Selection of clamping points: To ensure the smoothness of turning, the overall center of gravity should be clamped as much as possible. The journal reference of the part should be selected for clamping and close to the stop. However, the turning part of the previous process and the reference shaft are buried in the chuck and cannot be aligned. By observing the process route, it can be seen that adding the turning of the toothed spoke plate and the outer diameter of the lower step can not only increase the alignment point for the internal cavity machining, but also offset the influence of heat treatment deformation on the thickness and curvature of the spoke plate. The subsequent process has been improved.

[0065] (3) Selection of machining method: To prevent excessive machining allowance from causing stress deformation, roughing and finishing can be carried out separately when machining the cavity to release stress. First, rough machine the part, leaving a 0.2mm allowance on one side of the inner diameter surface, and do not machine the inner diameter annular groove. Unload the part and let it stand still for 2 hours to release the stress of the part. Re-clamp the part and finish machine the inner diameter using the previous clamping method.

[0066] (4) Selection of machining path: For internal diameter turning, rough turning mainly uses Z-axis feed to ensure that the internal diameter insert cuts into the cutting edge and reduce the resistance of the insert to the part. For main cutting, use R0.4 internal diameter insert, single layer 0.4 cutting amount, speed 500 r / min, feed 0.1. For finish turning, turn along the internal cavity path, single layer 0.1 cutting amount, speed 1000 r / min, feed 0.05.

[0067] Step 6: Determine the method for controlling the eccentricity of the parts in the post-heat external grinding process, and formulate a method for controlling vibration marks for the cavity structure to improve surface roughness;

[0068] Choosing two datums with a relatively large axial distance—the joint datum between the double-sided bearing shaft and the gear major diameter—as the overall axis of the part is more reasonable for alignment after hot machining. After establishing the axis, inspect all carburized areas of the part before machining, and determine whether the dimensional requirements are met based on the grinding allowance at each location. After hot machining, re-grind the centers to check the two newly selected locations, and then grind the datum shaft. During subsequent machining, align the gear tooth major diameter and the two side bearing shafts, and check the runout of the datum shaft in the middle. Before finish grinding the journal, align the datum, and simultaneously check that the runout of the gear teeth and spline pitch circle is within 0.02, and check that the runout of the journal to be ground is within 0.01.

[0069] Use a substitute tooling for the original input gear for clamping, such as... Figure 3 -6. The substitute tooling is a long rod structure with annular outer centers at both ends that mate with the center holes of bevel gears, and is locked in place by external nuts. Before machining, tighten the center holes at both ends of the substitute rod and align the outer diameter reference before machining. This can improve the cylindricity from 0.02 to 0.005 and reduce radial tightening deformation by approximately 0.01.

[0070] Step 7: Determine the method for controlling the eccentricity of the part in the post-heat grinding process, and customize the grinding allowance and penetration depth control scheme according to the tooth deformation.

[0071] The grinding quality of the gear teeth is determined by the grinding quality of the reference shaft. Rough machining before heat treatment ensures the pitch circle of the gear teeth is properly aligned with the reference shaft. During post-heat machining of the journal reference, the runout of the rough-machined pitch circles of each tooth is checked, and the eccentricity of the pitch circles on the tooth surface is controlled. During the gear grinding process, the grinding mandrel is positioned with the reference shaft. Before machining, a probe is used to check whether the allowance on the left and right tooth surfaces is uniform, generally controlled within 0.03 mm. Gears with good tooth condition before machining will meet the requirements for tooth parameters, the uniformity of the tooth surface diffusion layer depth, and the alignment requirements with the shaft axis after machining.

[0072] (1) Reduce the length of the mandrel, retaining only the effective length to prevent bending deformation. Increase the size of the center holes at both ends of the substitute shaft journal to increase the contact area between the two ends and the machine tool center, and strengthen the support force, such as... Figure 3 -8.

[0073] (2) Change the feed path, check the dimensions of several sections in the tooth width direction before fine grinding, and adjust the grinding path according to the dimensional deviation on the tooth surface to compensate for the defective parts in reverse.

[0074] (3) To prevent hollow vibration during processing, elastic cotton or other fillers can be filled into the inner hole of the grinding area.

[0075] Step 8: Balance process control. Add a pre-balancing process. Adjust the key positions and imbalance of parts before balancing by changing local tolerances.

[0076] The process route was revised, and the deformation and eccentricity of the parts were reduced by changing the process methods, thereby reducing the initial imbalance.

[0077] (1) After stabilizing the tempering, reduce the amount of machining on the CNC lathe. Leave a allowance of about 0.5mm on the entire surface of the part, including the inner hole and spline end face. The allowance in local positions can be adjusted according to the original allowance, but it should not be less than 0.2mm.

[0078] (2) After nitriding, the alignment requirement of the shaft diameter-spline joint datum is increased. The positioning datum is ground to include the shaft diameter datum and the center datum, ensuring that the runout between the tooth tip, shaft diameter and center is within 0.005.

[0079] (3) Add a nitrided model surface machining process. Clamp the reference surface and check that the grinding reference surface of the previous process is within 0.005mm before turning the part surface. Pay attention to the following points: 1. The clamping force should not be too large, and use a finish turning soft jaw clamp. 2. When turning, try to use a tool with a small rake angle and a sharp cutting edge to reduce the zero cutting resistance and prevent deformation. 3. During rough turning and finish turning, the part can be unloaded and re-clamped to release machining stress and prevent stress deformation of the part after one-time forming turning. 4. Auxiliary supports are required during turning, such as center rests, machine tool centers, etc. Depending on the deformation, multi-positioning point fixtures may be used if necessary.

[0080] (4) Add a stress relief process after turning to prevent stress relief deformation.

[0081] (5) Use special fixtures to process external grinding and gear grinding to avoid twisting and deformation of different cross sections due to improper clamping, which will cause stress accumulation during processing.

Claims

1. A method for controlling eccentric deformation during cold working of transmission shaft parts, characterized in that, include: Step 1: Adjust the axial and radial dimension allowances of the parts before heat treatment, ensuring that at least the parts requiring diffusion layering have the allowance calculated according to the diffusion layer dimensions. Step 2: Adjust the thin-walled shaft diameter section and spoke section of the part structure before heat treatment to reduce the complexity of the pre-heat treatment structure, increase the support force, and prevent the spokes from deforming under stress. Step 3: Establish machining datum after heat treatment: In order to prevent the dimensional deviation of the diffusion layer caused by the eccentricity of the parts and the inability to machine to the final state in some areas, a joint datum should be established after heat treatment to evenly distribute the machining allowance of the parts and avoid the above situation caused by severe deformation in a certain position. Step 4: Design post-heat treatment processes, rationally arrange post-heat treatment machining processes, determine alignment methods and check runout locations, give alignment values, and refine machining steps and allowances; Step 5: Determine the method for controlling the eccentricity of the part during post-heat turning, and provide specific turning schemes for the outer shape and inner cavity of the long shaft; Step 6: Determine the method for controlling the eccentricity of the parts in the post-heat external grinding process, and formulate a method for controlling vibration marks for the cavity structure to improve surface roughness; Step 7: Determine the method for controlling the eccentricity of the part in the post-heat grinding process, and customize the grinding allowance and penetration depth control scheme according to the tooth deformation. Step 8: Balance process control. Add a pre-balancing process and adjust the key positions and imbalance of parts before balancing by changing local tolerances.

2. The method according to claim 1, characterized in that, Adjusting the axial allowance includes: Based on the previous deformation patterns, the allowance for the total length of the shaft diameter before heat treatment should be no less than 1 mm on each side, and the allowance for local positions on the shaft diameter should be no less than 0.5 mm. If there is a spoke structure, the allowance for each side of the spokes should be no less than 0.7 mm.

3. The method according to claim 1, characterized in that, Adjusting the radial allowance includes: For non-carburized surfaces that are easy to machine, the allowance on one side shall not be less than 1 mm, and the allowance on thin-walled surfaces shall be increased to 2 mm; for non-carburized surfaces that are difficult to machine, the allowance on one side shall not be less than 0.5 mm; for parts that cannot be machined, pre-heat machining shall be performed to the final stage.

4. The method according to claim 1, characterized in that, Adjustments were made to the thin-walled shaft diameter section and spoke section of the part structure before heat treatment, including: For thin-walled shaft diameter sections, reduce complex pre-heating structures and replace them with through-rod structures; For the spoke section, a reinforced rounded base is added with a radius one-third of the spoke's radial length to enhance support. If the part has a spoke hole structure, the bottom hole is machined out before heat treatment to allow the heat treatment quenching oil to flow and prevent the spoke from deforming under stress. Before heat treatment, the dimensional arrangement is based on the post-heat treatment reference surface as the starting surface to reduce the risk of insufficient machining allowance caused by dimensional chain movement due to heat treatment deformation.

5. The method according to claim 1, characterized in that, Establish machining standards after heat treatment, including: The first step is to align the overall axis of the part after heat treatment to reduce local deviations and runout; use a three-jaw chuck to clamp one side of the shaft diameter of the part, with a 5mm ring at the clamping end; check the runout of the left reference shaft, align the runout of the other end, and repeatedly adjust the shaft diameter with larger runout until the runout of the reference shafts at both ends is within 0.

015. The second step is to check the pitch circle runout of the teeth and splines of the part. Use a four-jaw chuck to hold a three-jaw chuck and adjust the runout of the part radially to ensure that the pitch circle runout is within 0.

05. The third step involves fine-tuning the movement of each part using the same method as the second step, taking into account the processing allowance and penetration depth of each part, to ensure that the movement of each part meets the requirements. Machining the center hole and grinding the datum surface are used for clamping and alignment in subsequent processes. Before and after finishing processes such as precision turning, grinding the center hole, and precision grinding, the runout of the part is checked. If the runout is large in a certain area, the datum is corrected using the second step.

6. The method according to claim 1, characterized in that, The machining process includes: sequentially performing internal and external shaping, milling, grinding the center hole, external grinding, internal grinding, and gear grinding.

7. The method according to claim 1, characterized in that, Determine the method for controlling the eccentricity of parts during the post-heat grinding process, and develop a method for controlling vibration marks based on the cavity structure to improve surface roughness, including: Select two datums with a relatively large axial distance—the joint datum between the double-sided bearing shaft and the gear major diameter—as the overall axis of the part. This is more reasonable for alignment after hot machining. After establishing the axis, check all carburized parts of the part before machining. Determine whether the dimensional requirements are met based on the grinding allowance at each location. After hot machining, re-grind the center, check the two newly selected datums, and then grind the datum shaft. During subsequent machining, align the gear tooth major diameter and the two side bearing shafts, and check the runout of the datum shaft in the middle. Before fine grinding the journal, align the datum, and at the same time check that the runout of the gear teeth and spline pitch circle is within 0.02, and check that the runout of the journal to be ground is within 0.

01. The original input gear substitute tooling is selected for clamping; the substitute tooling is a long rod structure with annular external centers at both ends of the rod that mate with the center holes of the bevel gear, and external nuts are used for locking; before machining, the center holes at both ends of the substitute tooling are tightened, and the outer diameter reference is aligned for machining; the cylindricity is improved from 0.02 to 0.005, and the radial clamping deformation is reduced by about 0.01.

Images