某手动传动薄壁直齿轮未经装机使用便在齿间发现了多条裂纹, 对裂纹形貌、断口特征进行了分析, 从设计、加工、装配等过程对失效原因进行了排查。结果表明: 该传动直齿轮出现的裂纹为振动疲劳所致, 直齿轮产生振动的原因是其在磨削加工时的夹具选择不当, 使齿轮产生倾斜, 给直齿轮施加了一个轴向分力, 导致直齿轮发生共振; 通过更改夹具结构, 采用夹辐板的装夹方式可以有效避免该类裂纹的出现。

Several cracks were found among the teeth of a manual thin walled drive spur gear before service, the cracks morphology and fracture characteristics were analyzed, and the failure causes were identified during the design, processing, assembly and other processes. The results show that the feature of the cracks in the spur gear are vibration fatigue. Because of improper clamping fixture, an extra axial component force is imposed on the spur gear during abrasive machining, which resulted in resonance vibration of the gear. By changing the fixture structure and adopting the clamp wheel disk clamping way, this type of defect can be avoided effectively.