通过对汽车主轴齿轮在使用过程中断裂的分析,得出主轴齿轮主要是由于冷矫正过程中花键部分因截面积最小而承受了最大的弯曲应力,使齿轴局部发生过度塑性变形而产生裂纹源,从而在随后装配锤击螺母和汽车运行过程中,主轴因受到冲击载荷发生断裂。对该零件的热处理变形规律进行了分析讨论,提出了该零件生产工艺流程的改进建议。

The fracture reason for the principal axis gear of car was caused by bend stress according to the failure analysis results. Cracking initiated on spline due to local over plastic deformation in the process of cold leveling,because spline has the maximum bend stress for minimum section size. Impact load on the principal axis led to final fracture during nut assemblying and car running. The heat treatment deformation rule for the part was analyzed and discussed,the suggestion of improved manufacturing process was proposed.