装载机销轴断裂分析

某厂家生产的销轴在使用过程中多次在同一部位发生断裂。采用断口分析、化学成分分析、金相组织分析、硬度检验及CAE模拟受力分析等试验方法对两个销轴的断裂原因进行了分析。结果表明：销轴径向油孔位置具有随机性，当油孔位于最大弯曲应力一侧时，由于油孔的应力集中作用，导致油孔口位置的应力过大，在油孔口位置萌生疲劳裂纹，故油孔位置不合适是销轴断裂的主要原因。另外，销轴表面硬化层深度偏低，降低了失效件的疲劳强度，也是销轴早期疲劳断裂的重要原因。因此，通过在销轴生产时避免将油孔置于弯曲应力最大的一侧，同时增加表面硬化层的深度，可有效地避免类似故障的发生。

Fracture Analysis on Pins of Loader

Several pins fractured during service at the same position. Two of them were investigated. The failure cause of the pins was analyzed by fracture surface observation, chemical composition analysis, metallurgical structure and hardened ease depth examination, and stress analysis by CAE. The results show that the fracture of the pins mainly resulted from the improper location of the oil holes. The oil holes were random located in the pins. If the oil hole was located in the side under the effect of the maximal bending stress, stress concentration effect of the oil hole would lead to overlarge stress at the port of the oil hole. As a result,fatigue cracks initiated at the port of the oil orifice. In addition, lower fatigue resistance resulting from thinner hardened case is another cause for the early fatigue fracture of the pins. According to the analysis above, the similar fatigue fracture of the pins can be avoided by locating the oil holes in the side under the effect of the lower bending stress and increasing the depth of the surface hardened cases.