通过断口分析、化学成分分析、硬度测试等方法, 对某液压泵壳体螺纹的拉脱原因进行了分析。结果表明: 液压泵壳体螺纹拉脱的失效性质为剪切疲劳断裂; 循环散热导管接头装配过紧, 造成了液压泵壳体螺纹损伤, 是导致剪切疲劳断裂的原因; 为有效避免螺纹拉脱故障, 应增加管接头与液压泵壳体螺纹的有效配合长度。

In order to analyze the reason for pull-off of hydraulic pump body thread, the means, such as fracture analysis, chemical composition analysis and hardness testing, were conducted. The results showed that the hydraulic pump body thread failed due to cutting fatigue fracture, and the main cause of thread fatigue fracture was the joint to the circle radiating pipe was assembled too tightly, it made the hydraulic pump body thread damaged. In order to void the thread fracture again, the effective thread conjugate length between hydraulic pump body and pipe joint should be increased.