有利于提高硬态切削滚动轴承疲劳寿命的残余应力临界条件

超精硬态切削在滚动轴承表面形成的残余压应力 ,经工作应力衰减后才成为影响滚动接触疲劳寿命的应力状态。基于此 ,本文在考虑特定滚动轴承使用条件的基础上 ,推导出滚动轴承采用超精硬态切削加工工艺时 ,已加工表面的残余应力需要满足的两个临界条件 ,即在接触区的每一离散点的残余应力必须与工作应力符号相同 ,且随时间变化残余应力的幅值应小于或等于工作应力幅值的两倍时 ,才有利于提高滚动轴承的使用寿命。该结论澄清了长久以来文献中所提出的残余压应力总是有利于提高工件疲劳寿命的这个似是而非的概念。

Critical Conditions of Residual Stresses to Optimize Fatigue Life of Rolling Bearings in Superfinish Hard Turning

The residual stress formed on the surface of rolling bearing in superfinish hard turning will influence the fatigue life of rolling contacting after stress decay. Based on it, two critical conditions that the residual stress on the finished surface should satisfies in superfinish hard turning, that the residual stress has to be of the same sign as the service stress at every point on the service stress profile and the magnitude of the residual stress should be less than or equal to twice the magnitude of the service stress with temporal change, are supposed to optimize the service life of rolling bearing. The result make clear the ambiguous concept that the compressive stress will always benefit component's fatigue life.