对频繁出现轮齿早期断裂的变速箱六档齿轮进行了分析。通过对齿轮断裂特征、显微组织、硬度等方面的综合分析, 确定了其断裂形式为低应力高周疲劳断裂。由裂纹扩展过程判断齿轮轮辐设计强度不足是导致其大批量早期疲劳失效的根本原因。据此通过改进齿形、油孔等设计措施, 降低齿根部的设计应力水平, 解决了这一问题。

Frequent preliminary fracture of six speed gears of transmission have been investigated by means of analysis on fracture feature, microstructure hardness and so on. The results showed that the fracture model was low stress and high cycle fatigue fracture. It was indicated by crack propagation process that the insufficient design strength of gear spoke was the primary cause of the kind of gear fatigue fracture in the primary stage. Accordingly, such problem would be resolved by bending stress reduction of gear root, which could be achieved through the design modification of gear tooth shape and oilhole.