Improved structure of motorcycle main and auxiliary shafts and gear machining process and device thereof

Abstract

The application relates to the technical field of gear machining process, and discloses a motorcycle main and auxiliary shaft improved structure, a gear machining process and a device thereof. The machining process comprises the following steps: blanking and forging, isothermal normalizing, rough turning, key pulling, fine turning, gear hobbing, gear shaving, chamfering, fine inserting, deburring, carburizing and quenching, low-temperature tempering, polishing, straightening, external grinding and final inspection. During the isothermal normalizing, different cooling is carried out on different diameter shaft sections; during the fine turning, different expansion forces are applied to different diameter shaft sections by using taper mandrels; during the carburizing and quenching, local carburizing is carried out on large modulus gears; and during the straightening, different straightening pressures are applied to different diameter shaft sections. The application carries out different control on process parameters of different parts of the asymmetric structure gear, and effectively improves the gear machining precision and the finished product qualification rate.

Description

Technical Field

[0001] This invention relates to the field of gear processing technology, and in particular to an improved structure for a motorcycle main and auxiliary shaft, as well as its gear processing technology and apparatus. Background Technology

[0002] The main and countershaft gears in a motorcycle gearbox play a crucial role in power transmission, and their machining quality directly affects the overall transmission efficiency, running smoothness, and service life of the vehicle. Currently, the typical machining process for motorcycle main and countershaft gears usually includes multiple steps such as blanking and forging, normalizing, rough turning, spline drawing, finish turning, gear hobbing, gear shaving, chamfering, precision shaping, deburring, carburizing and quenching, low-temperature tempering, polishing, straightening, external grinding, and final inspection. These processes have largely become standardized operating procedures in gear manufacturing companies.

[0003] However, with the continuous increase in motorcycle engine power and torque, the load on gearbox gears is increasing, leading to more complex structural designs for the main and auxiliary shaft gears. Existing technologies have introduced asymmetrical structural designs with bosses on the auxiliary shaft, different diameters for different shaft sections, and different modules for different gears, in order to improve the load-bearing capacity and reliability of the gearbox. However, while these structural improvements enhance mechanical properties, they also introduce new technical challenges to gear manufacturing. Due to the differences in diameter between different shaft sections on the same gear shaft and the different modules of different gears, significant differences exist between the larger diameter and smaller diameter sections in terms of cooling rate, clamping force, carburized layer growth, and straightening pressure response during key processes such as isothermal normalizing, precision machining, carburizing and quenching, and straightening.

[0004] The existing processing technology uses the same processing parameters for all parts, without considering the impact of shaft diameter differences on cooling uniformity or the different requirements for carburized layer depth due to module differences. This results in large bending deformation of gear shafts after heat treatment, inconsistent hardened layer depths for different gears, and difficulty in controlling straightening accuracy, which seriously affects the final accuracy of gears and the yield of finished products. Summary of the Invention

[0005] The purpose of this invention is to provide an improved structure for the main and auxiliary shafts of motorcycles, as well as its gear machining process and apparatus, which solves the problems of low gear machining accuracy and poor finished product qualification rate caused by the failure to consider the differences in diameter of different shaft sections and the differences in gear modules in the prior art. To achieve the above objectives, the present invention provides a machining process for motorcycle main and auxiliary shaft gears, comprising the following steps: Round steel bars are selected, heated after blanking, and forged into gear blanks using a die forging process. The forged blank is subjected to isothermal normalizing treatment; Rough turning the outer diameter and end face of the gear blank on a CNC lathe; A broaching machine and a spline broach are used to broach the spline hole on the gear blank; Using the spline hole as the positioning reference, the outer circle, end face and groove of the upper mandrel are precision machined to the design dimensions; Gear teeth are machined using a gear hobbing machine; The gears after hobbing are precision machined using a gear shaving machine; Chamfer the ends of the gear teeth to remove sharp edges; A gear shaper is used to precision shape the keyway or special tooth profile of the gear; Remove burrs from all parts of the gears; The gears were placed in a carburizing furnace for gas carburizing, followed by direct quenching. The quenched gears are heated, held at that temperature, and then air-cooled. Polishing equipment is used to polish the gear surface to remove the surface oxide layer; A straightening machine is used to straighten the gear shaft that has bent after heat treatment; The outer diameter and mating surfaces of the gear shaft are precision ground using an external cylindrical grinding machine; The finished gears are inspected for dimensional accuracy, tooth profile accuracy, surface hardness, and carburized layer depth.

[0006] In the isothermal normalizing step, different cooling is performed on different diameter parts of the gear shaft, with auxiliary forced cooling used for larger diameter parts and natural cooling for smaller diameter parts. In the steps of using the spline hole as the positioning reference and precision machining the outer circle, end face and groove to the design size with the upper mandrel, a tapered mandrel is used to tighten the upper mandrel of the workpiece inner hole for precision machining, and different tensioning forces are applied to shaft sections of different diameters. In the step of placing the gear in a carburizing furnace for gas carburizing and then directly quenching, the gear with a larger module is subjected to local carburizing treatment so that the effective hardened layer depth is greater than that of the gear with a smaller module. In the step of straightening the gear shaft that has been bent after heat treatment using a straightening machine, different straightening pressures are applied to shaft segments of different diameters.

[0007] In the isothermal normalizing step, the forged blank is heated to 920±10℃ and held for 120 minutes. The larger diameter parts are forced to cool to 650±20℃ with compressed air, while the smaller diameter parts are cooled naturally. After the overall temperature reaches 650±20℃, it is held isothermally for 60 minutes and then air-cooled to room temperature. In the steps of using the spline hole as the positioning reference and precision machining the outer circle, end face and groove of the mandrel to the design size, the tensioning force of the shaft section with a larger diameter is greater than that of the shaft section with a smaller diameter, and the tensioning force is increased by 10% to 15%. In the step of placing the gear in a carburizing furnace for gas carburizing and then directly quenching, the carburizing temperature is 930±5℃, the total carburized layer depth is controlled at 0.8~1.2mm, the local supplementary carburizing time for gears with larger modules is 15~20 minutes, so that the effective hardened layer depth reaches 1.1~1.2mm, and the effective hardened layer depth for gears with smaller modules is controlled at 0.8~0.9mm. In the step of straightening the gear shaft that has bent after heat treatment using a straightening machine, the straightening pressure applied to the shaft section with a larger diameter is 1.2 to 1.5 times that of the shaft section with a smaller diameter, and the straightening accuracy is controlled within 0.02 mm.

[0008] In the step of selecting round steel bars, heating them after blanking, and forging them into gear blanks using a die forging process, 20CrMo round steel bars are selected, heated to 1150-1200℃, and the forging ratio is not less than 3.

[0009] In the step of broaching spline holes on the gear blank using a broaching machine and a spline broach, the outer circle of the gear blank is used as a correction reference before broaching, and the runout accuracy of the outer circle of the gear blank is corrected to be within 0.02 to 0.04 mm. In the step of machining the gear teeth using a gear hobbing machine, the shaving allowance for the gear hobbing is 0.07 to 0.10 mm. In the step of finishing the gear after hobbing with a gear shaving machine, the length of the common normal is machined to the upper limit of the dimension; In the step of heating and holding the quenched gear, followed by air cooling, the quenched gear is heated to 180±10℃, held for 120 minutes, and then air cooled.

[0010] The present invention also provides an improved structure for the main and auxiliary shafts of a motorcycle, which is manufactured using the aforementioned process.

[0011] The present invention also provides a machining device for motorcycle main and auxiliary shaft gears, used for machining the aforementioned improved motorcycle main and auxiliary shaft structure.

[0012] This invention discloses an improved structure for the main and auxiliary shafts of a motorcycle, along with its gear machining process and apparatus. Addressing the differences in diameter at different sections of the gear shaft, differentiated cooling is implemented during the isothermal normalizing process. This effectively eliminates the problem of uneven cooling caused by cross-sectional differences, significantly improving the uniformity of hardness between shaft sections after normalizing and providing a uniformly structured blank foundation for subsequent machining. To address the differences in diameter at different sections of the gear shaft, a tapered mandrel is used during the precision machining and clamping process to apply different tension forces to different shaft sections. This effectively compensates for the uneven clamping force caused by the asymmetrical structure, ensuring the coaxiality of the machining datum and the assembly datum. To address the differences in the module of gears at different gear positions, localized supplementary carburizing is applied to large-module gears during the carburizing and quenching process, resulting in a deeper and more effective hardened layer. This avoids the problem of insufficient core hardness in large-module gears and overly brittle carburized layers in small-module gears, which is common in traditional uniform carburizing processes. To address the differences in diameter at different sections of the gear shaft, asymmetrical straightening pressure loading is implemented during the straightening process. This effectively offsets the differences in deformation response of the asymmetrical structure during straightening, improving straightening accuracy and product yield. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0014] Figure 1 This is the first embodiment of the present invention. Detailed Implementation

[0015] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0016] This invention provides a machining process for motorcycle main and auxiliary shaft gears, comprising the following steps: S1: Select round steel bars, heat them after cutting, and forge them into gear blanks using a die forging process.

[0017] Specifically, select 20CrMo round steel bars, heat them to 1150-1200℃, and forge a ratio of not less than 3.

[0018] In this embodiment, a circular saw is used to cut the material to a predetermined length during blanking, and the flatness of the end face is controlled within ±0.5mm. Heating is performed using a medium-frequency induction heating furnace, with a heating rate controlled at 8-10℃ / s to ensure uniform temperature between the core and surface of the bar stock. Forging is carried out on a hot forging press, with a final forging temperature not lower than 850℃, followed by natural cooling using residual heat. After forging, batch sampling is conducted to inspect the streamline distribution and grain size of the blanks, ensuring that the forging streamlines are continuously distributed along the tooth profile and that the grain size is not lower than grade 5.

[0019] S2: The forged blank is subjected to isothermal normalizing treatment.

[0020] Specifically, differentiated cooling is applied to different diameter parts of the gear shaft, with auxiliary forced cooling used for larger diameter parts and natural cooling for smaller diameter parts.

[0021] The forged blank is heated to 920±10℃ and held for 120 minutes. Larger diameter parts are forced to cool to 650±20℃ with compressed air, while smaller diameter parts are cooled naturally. Once the overall temperature reaches 650±20℃, it is held at the same temperature for 60 minutes, and then air-cooled to room temperature.

[0022] In this embodiment, the blanks are arranged on the normalizing tray, with a spacing of not less than 20 mm between adjacent blanks to ensure airflow. Heating is carried out in a continuous isothermal normalizing furnace, with a nitrogen protective atmosphere inside the furnace to prevent surface decarburization. Auxiliary forced cooling is achieved by setting a compressed air nozzle array at the furnace outlet. The number of nozzles that are open is automatically adjusted according to the diameter of the shaft section. The nozzles are fully open for sections with a diameter greater than the reference value, and closed or half-open for sections with a smaller diameter. After the isothermal holding is completed, the blanks are taken out of the furnace and allowed to cool naturally in the air. During the cooling process, an infrared thermometer is used to monitor the temperature field distribution in real time to ensure overall cooling uniformity.

[0023] S3: Rough turn the outer diameter and end face of the gear blank on a CNC lathe.

[0024] In this embodiment, a dual-spindle CNC lathe is used for rough turning. The spindle speed is controlled at 300-500 r / min, the feed rate is 0.3-0.5 mm / r, and the depth of cut is 2-3 mm. The blank is clamped using a hydraulic chuck, and the clamping pressure is controlled at 2.0-2.5 MPa to prevent clamping deformation. After rough turning, the cutting chips on the workpiece surface are removed with an air gun, and the outer diameter is re-measured with a vernier caliper to ensure that the allowance on one side is uniform.

[0025] S4: Use a broaching machine and a spline broach to broach the spline hole on the gear blank.

[0026] Specifically, before broaching, the outer circle of the gear blank is used as the calibration reference, and the runout accuracy of the outer circle of the gear blank is calibrated to be within 0.02 to 0.04 mm.

[0027] In this embodiment, a vertical broaching machine is used for broaching, and the broaching speed is controlled at 4-6 m / min. The gear blank is mounted on a special positioning fixture, and the outer circle of the gear blank is used as the calibration reference. A dial indicator is used to detect the runout of the outer circle at four evenly distributed measuring points in the circumferential direction. If the runout exceeds the tolerance, it is corrected by adjusting the fine-tuning screw on the fixture. An involute spline broach is used, and the broach material is powder metallurgy high-speed steel. During the broaching process, cutting fluid is used for sufficient cooling and lubrication. The cutting fluid is an emulsion with a concentration controlled at 5%-8%. After broaching, spline gauges are used to inspect each spline hole.

[0028] S5: Using the spline hole as the positioning reference, the outer circle, end face and groove of the upper mandrel are precision machined to the design dimensions.

[0029] Specifically, a tapered mandrel is used to tension the mandrel on the inner hole of the workpiece during precision machining, and different tensioning forces are applied to shaft sections of different diameters.

[0030] The tension force of a shaft section with a larger diameter is greater than that of a shaft section with a smaller diameter, and the increase in tension force is 10% to 15%.

[0031] In this embodiment, the tapered mandrel is a hydraulically tensioned mandrel with a taper of 1:5000. During clamping, the mandrel is first inserted into the spline hole, and then hydraulic oil is introduced into the inner cavity of the mandrel to make the outer wall of the mandrel evenly tensioned and fit against the inner wall of the spline hole. The output pressure of the hydraulic station is set according to the diameter of the shaft section: the hydraulic pressure corresponding to the shaft section with a larger diameter is 4.0 to 4.5 MPa, and the hydraulic pressure corresponding to the shaft section with a smaller diameter is 3.5 to 4.0 MPa. The finish turning is completed on a CNC lathe with one clamp and one support, the spindle speed is 600 to 800 r / min, the feed rate is 0.1 to 0.2 mm / r, and the depth of cut is 0.2 to 0.5 mm.

[0032] S6: Gear teeth are machined using a gear hobbing machine.

[0033] In this embodiment, a six-axis CNC hobbing machine is used, and the hob is a single-head right-hand involute hob. The hobbing cutting parameters are: spindle speed 200-400 r / min, axial feed 0.8-1.2 mm / r, and radial depth of cut completed in three feeds: rough hobbing depth of 1.0 mm, semi-finish hobbing depth of 0.5 mm, and finish hobbing depth of 0.2 mm. During the hobbing process, oil-based cutting fluid is used for sufficient cooling, and the flow rate of the cutting fluid is not less than 30 L / min. After the hobbing is completed, the common normal length is measured using a common normal micrometer, and the radial runout of the gear ring is measured using a gear ring radial runout detector.

[0034] S7: Use a gear shaving machine to finish the gears after hobbing.

[0035] Specifically, the length of the common normal is machined to the upper limit of the dimension.

[0036] In this embodiment, the gear shaving machine is a CNC gear shaving machine, and the shaving cutter is a disc-shaped shaving cutter that matches the gear parameters, made of M35 high-speed steel. The shaving processing parameters are: shaving cutter speed 150-200 r / min, axial feed 0.3-0.5 mm / r, radial feed 0.02-0.04 mm / pass, completed in 3-5 passes. During the shaving process, a special cutting oil for gear shaving is used for sufficient lubrication and cooling. After the shaving is completed, a gear measuring center is used to check the tooth profile accuracy to ensure that the tooth profile error and tooth direction error meet the requirements of subsequent heat treatment.

[0037] S8: Chamfer the ends of the gear teeth to remove sharp edges.

[0038] In this embodiment, the chamfering is performed using a CNC chamfering machine with a chamfering angle of 30° to 45° and a chamfering width of 0.5 to 1.0 mm. The machining process is completed in two passes: tooth tip chamfering and tooth root chamfering. The spindle speed is 800 to 1200 r / min and the feed rate is 0.1 to 0.2 mm / r. After the chamfering is completed, visual inspection and touch inspection are used to ensure that all sharp edges at the tooth tip have been uniformly removed and that there are no residual burrs or steps.

[0039] S9: Use a gear shaper to perform precision shaping on the keyway or special tooth profile of the gear.

[0040] In this embodiment, the gear shaping machine is a CNC gear shaping machine, and the gear shaping cutter is made of high-speed steel. The tooth profile of the gear shaping cutter matches the special tooth profile of the workpiece. The shaping parameters are: 200-300 strokes / min, circumferential feed rate 0.2-0.4mm / stroke, and radial depth of cut fed in three stages: rough shaping 0.3mm, semi-finish shaping 0.15mm, and finish shaping 0.05mm. During the shaping process, cutting fluid is used to flush the cutting area and remove chips in a timely manner.

[0041] S10: Remove burrs from all parts of the gear.

[0042] In this embodiment, deburring is performed using a combination of mechanical brushing and manual finishing. First, a nylon brush wheel is used to brush the outer tooth surface of the gear at a speed of 500-700 r / min, brushing back and forth 3-5 times to remove tiny burrs from the tooth surface. Then, the operator uses a fine file and an oilstone to manually finish the ends of the spline hole, the keyway opening, and the chamfered area of ​​the tooth ends. After finishing, compressed air is used to blow away metal shavings from the surface of the workpiece and the hole, and a visual inspection is performed to ensure that there are no residual burrs.

[0043] S11: The gear is placed in a carburizing furnace for gas carburizing, and then directly quenched.

[0044] Specifically, gears with a larger module undergo localized infiltration treatment to ensure that the effective hardened layer depth is greater than that of gears with a smaller module.

[0045] The carburizing temperature is 930±5℃, and the total carburized layer depth is controlled at 0.8~1.2mm. For gears with a larger module, the local carburizing time is 15~20 minutes to make the effective hardened layer depth reach 1.1~1.2mm. For gears with a smaller module, the effective hardened layer depth is controlled at 0.8~0.9mm.

[0046] In this embodiment, a continuous gas carburizing automated production line is used. The carburizing atmosphere is a mixture of methanol cracking gas and propane enriched gas, and the carbon potential control accuracy is ±0.05%. During furnace loading, the gears are arranged in sections according to their module size, with gears of larger module size placed near the enriched gas inlet. The carburizing process is divided into four stages: heating and venting, strong carburizing, diffusion, and cooling and homogenization. The total carburizing time is approximately 4 to 6 hours. The supplementary carburizing treatment is achieved by introducing enriched gas for an additional 15 to 20 minutes into the area where the gears of larger module size are located after the strong carburizing stage and before the diffusion stage. After carburizing, the workpiece is directly oil quenched at a temperature of 60 to 80°C, and the workpiece is cooled in the oil for no less than 10 minutes.

[0047] S12: Heat the quenched gear, hold it at that temperature, and then air cool it.

[0048] Specifically, the quenched gear is heated to 180±10℃, held at that temperature for 120 minutes, and then air-cooled.

[0049] In this embodiment, a continuous mesh belt tempering furnace is used for tempering. The workpieces are evenly laid on the mesh belt, and the thickness of the material layer does not exceed twice the height of a single workpiece layer. The tempering furnace is electrically heated, and the temperature uniformity of the furnace chamber is controlled within ±5℃. After the workpieces are taken out of the quenching tank, they are cleaned and dried and immediately loaded into the tempering furnace, with an interval of no more than 2 hours. After holding at this temperature for 120 minutes, the workpieces are taken out of the furnace with the mesh belt and allowed to cool naturally to room temperature in the air. After tempering, the hardness is tested by sampling in batches.

[0050] S13: Polish the gear surface using polishing equipment to remove the surface oxide layer.

[0051] In this embodiment, a planetary centrifugal polishing machine is used for polishing. The polishing medium is high-alumina ceramic abrasive with a particle size of 240 mesh. The polishing liquid is a water-based polishing liquid containing rust inhibitor. The volume ratio of the workpiece to the abrasive is 1:3 to 1:5. The polishing time is 30 to 60 minutes, and the drum speed is 40 to 60 r / min. After polishing, the workpiece is removed, and a high-pressure water gun is used to clean the surface to remove residual polishing liquid and abrasive debris. Then, it is dried.

[0052] S14: A straightening machine is used to straighten the gear shaft that has been bent after heat treatment.

[0053] Specifically, different straightening pressures are applied to shaft segments of different diameters.

[0054] The straightening pressure applied to the shaft section with a larger diameter is 1.2 to 1.5 times that of the shaft section with a smaller diameter, and the straightening accuracy is controlled within 0.02 mm.

[0055] In this embodiment, before straightening, a gear measuring center is used to detect the bending deformation of the gear shaft, and the maximum bending point and bending direction are marked. The straightening machine is a servo-controlled automatic straightening machine, which automatically calculates the straightening point and straightening stroke based on the detection data. The gear shaft is placed horizontally on the V-shaped support of the straightening machine, and the pressure head is aligned with the radial opposite of the maximum bending point. The support spacing is automatically adjusted according to the shaft diameter, with larger diameter shafts corresponding to larger support spans. Straightening adopts a segmented multiple pressure application method, and the springback is detected after each pressure application, gradually approaching the target accuracy until the runout accuracy is controlled within 0.02mm.

[0056] S15: The outer diameter and mating surfaces of the gear shaft are precision ground using an external cylindrical grinding machine.

[0057] In this embodiment, the external cylindrical grinding machine is a CNC universal external cylindrical grinding machine, which adopts a two-center clamping method, and the center clamping force is controlled at 150-200N; the grinding uses a ceramic bonded white corundum grinding wheel, and the grinding parameters are: grinding wheel linear speed 35-45m / s, workpiece rotation speed 60-100r / min, feed rate 0.005-0.015mm / cycle, which is completed in four stages: rough grinding, semi-finish grinding, finish grinding and sparkless grinding; the grinding process is fully cooled by grinding fluid, which is a water-based synthetic grinding fluid, and the spray pressure is 0.3-0.5MPa.

[0058] S16: Inspect the dimensional accuracy, tooth profile accuracy, surface hardness, and carburized layer depth of the machined gears.

[0059] In this embodiment, dimensional accuracy inspection is performed using a coordinate measuring machine (CMM), checking key dimensions such as outer diameter, inner diameter, spline span, and gear common normal length item by item. Tooth profile accuracy inspection uses a gear measuring center to check tooth profile error, tooth direction error, cumulative tooth pitch error, and radial runout of the gear ring. Surface hardness testing uses a Rockwell hardness tester, taking three measuring points on both the gear end face and outer cylindrical surface; the hardness value must reach HRC 58–62. The carburized layer depth is measured using metallography; a sample is taken from the middle of the gear tooth surface, and the effective hardened layer depth is measured using a metallographic microscope; the test results must meet design requirements.

[0060] The motorcycle main and auxiliary shaft gear machining process of this invention effectively solves the technical difficulties caused by cross-sectional and module differences in asymmetrical gear machining by implementing differentiated control for different diameter sections and different module gears in each key process. Specifically, differentiated cooling is implemented for different diameter sections in the isothermal normalizing step to eliminate the problem of uneven cooling caused by cross-sectional differences; in the precision turning step, tapered mandrels are used to apply different tension forces to shaft sections of different diameters to compensate for the uneven clamping force caused by the asymmetrical structure; in the carburizing and quenching step, local supplementary carburizing is implemented for large module gears to obtain an effective hardened layer depth that matches their respective requirements; in the straightening step, different straightening pressures are applied to shaft sections of different diameters to effectively offset the differences in deformation response of the asymmetrical structure during the straightening process. The above four differentiated control methods work together to ensure that the dimensional accuracy, tooth profile accuracy, surface hardness, and carburized layer depth of the final gear product all meet the design requirements.

[0061] The present invention also provides an improved structure for the main and auxiliary shafts of a motorcycle, which is manufactured using the aforementioned process.

[0062] The present invention also provides a machining device for motorcycle main and auxiliary shaft gears, used for machining the aforementioned improved motorcycle main and auxiliary shaft structure.

[0063] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A machining process for motorcycle main and auxiliary shaft gears, characterized in that, Includes the following steps: Round steel bars are selected, heated after blanking, and forged into gear blanks using a die forging process. The forged blank is subjected to isothermal normalizing treatment; Rough turning the outer diameter and end face of the gear blank on a CNC lathe; A broaching machine and a spline broach are used to broach the spline hole on the gear blank; Using the spline hole as the positioning reference, the outer circle, end face and groove of the upper mandrel are precision machined to the design dimensions; Gear teeth are machined using a gear hobbing machine; The gears after hobbing are precision machined using a gear shaving machine; Chamfer the ends of the gear teeth to remove sharp edges; A gear shaper is used to precision shape the keyway or special tooth profile of the gear; Remove burrs from all parts of the gears; The gears were placed in a carburizing furnace for gas carburizing, followed by direct quenching. The quenched gears are heated, held at that temperature, and then air-cooled. Polishing equipment is used to polish the gear surface to remove the surface oxide layer; A straightening machine is used to straighten the gear shaft that has bent after heat treatment; The outer diameter and mating surfaces of the gear shaft are precision ground using an external cylindrical grinding machine; The finished gears are inspected for dimensional accuracy, tooth profile accuracy, surface hardness, and carburized layer depth.

2. The machining process for motorcycle main and auxiliary shaft gears as described in claim 1, characterized in that, In the isothermal normalizing step, different cooling is performed on different diameter parts of the gear shaft, with auxiliary forced cooling used for larger diameter parts and natural cooling for smaller diameter parts. In the steps of using the spline hole as the positioning reference and precision machining the outer circle, end face and groove to the design size with the upper mandrel, a tapered mandrel is used to tighten the upper mandrel of the workpiece inner hole for precision machining, and different tensioning forces are applied to shaft sections of different diameters. In the step of placing the gear in a carburizing furnace for gas carburizing and then directly quenching, the gear with a larger module is subjected to local carburizing treatment so that the effective hardened layer depth is greater than that of the gear with a smaller module. In the step of straightening the gear shaft that has been bent after heat treatment using a straightening machine, different straightening pressures are applied to shaft segments of different diameters.

3. The machining process for motorcycle main and auxiliary shaft gears as described in claim 2, characterized in that, In the isothermal normalizing step, the forged blank is heated to 920±10℃ and held for 120 minutes. The larger diameter parts are forced to cool to 650±20℃ with compressed air, while the smaller diameter parts are cooled naturally. After the overall temperature reaches 650±20℃, it is held isothermally for 60 minutes and then air-cooled to room temperature. In the steps of using the spline hole as the positioning reference and precision machining the outer circle, end face and groove of the mandrel to the design size, the tensioning force of the shaft section with a larger diameter is greater than that of the shaft section with a smaller diameter, and the tensioning force is increased by 10% to 15%. In the step of placing the gear in a carburizing furnace for gas carburizing and then directly quenching, the carburizing temperature is 930±5℃, the total carburized layer depth is controlled at 0.8~1.2mm, the local supplementary carburizing time for gears with larger modules is 15~20 minutes, so that the effective hardened layer depth reaches 1.1~1.2mm, and the effective hardened layer depth for gears with smaller modules is controlled at 0.8~0.9mm. In the step of straightening the gear shaft that has bent after heat treatment using a straightening machine, the straightening pressure applied to the shaft section with a larger diameter is 1.2 to 1.5 times that of the shaft section with a smaller diameter, and the straightening accuracy is controlled within 0.02 mm.

4. The machining process for motorcycle main and auxiliary shaft gears as described in claim 1, characterized in that, In the step of selecting round steel bars, heating them after blanking, and forging them into gear blanks using a die forging process, 20CrMo round steel bars are selected, heated to 1150-1200℃, and the forging ratio is not less than 3.

5. The machining process for motorcycle main and auxiliary shaft gears as described in claim 1, characterized in that, In the step of broaching spline holes on gear blanks using a broaching machine and a spline broach, the outer circle of the gear blank is used as a correction reference before broaching, and the runout accuracy of the outer circle of the gear blank is corrected to be within 0.02 to 0.04 mm. In the step of machining the gear teeth using a gear hobbing machine, the shaving allowance for the gear hobbing is 0.07 to 0.10 mm. In the step of finishing the gear after hobbing with a gear shaving machine, the length of the common normal is machined to the upper limit of the dimension; In the step of heating and holding the quenched gear, followed by air cooling, the quenched gear is heated to 180±10℃, held for 120 minutes, and then air cooled.

6. An improved structure for a motorcycle main and auxiliary shaft, characterized in that, It is manufactured using the process described in any one of claims 1-5.

7. A machining device for motorcycle main and auxiliary shaft gears, characterized in that, Used for machining the improved motorcycle main and auxiliary shaft structure as described in claim 6.

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