The Heat Treatment Deformation Law and the Improvement of Accuracy of the Transmission Gear

Transmission is one of the core assembly units of automobile, and its performance has a decisive effect on the overall performance of automobile. And gear accuracy has the biggest influence on the performance of transmission, and to improve gear accuracy is the key point to improve the performance of transmission. But the heat treatment deformation of gear has become the tiger on the road (means the obstacle on the road) to improve gear accuracy, especially for the shaved gear which would not have finish machining after heat treatment. The heat treatment deformation quantity can directly influence gear accuracy, and as the factor of heat treatment is complicated and sophisticated, the deformation can be diminished as far as possible, but cannot be eliminated, usually we can try to diminish the deformation and analyze and summarize the deformation law to make a reverse machining, we do both at the same time to improve gear accuracy. This thesis through the analysis and researches on deformation law of gear heat treatment, tested and verified by gear shaved in FAW shaft and gear manufacturing center, finally made a summarization on the deformation law of gear heat treatment, and with this law, we can direct the machining of white parts, make a reverse modification to counteract the heat treatment deformation finally to achieve the goal of improving finished gear accuracy. Here are the researches done: 1. The influence of heat treatment deformation on gear common normal line; 2. The influence of heat treatment deformation on gear involute; 3. The influence of heat treatment deformation on gear helical line; 4. The influence of heat treatment deformation on gear tooth spacing; Through this research, the gear deformation law of heat treatment is summarized, and under the direction of this law, we can make a reverse modification machining to improve gear accuracy, and then to improve the performance of transmission.