Study on Oil Film formation of Rough Surfaces in Rolling Contact under Variable Load

进行了两次油压式脉动变载荷下的滚子试验，用电阻法测量了油膜的形成状态，并对部分弹流润滑特性进行了研究。(1)通过载荷幅值对油膜形成的影响和载荷周期与油膜电压互相关的测量结果，认识到挤压作用对油膜形成状态的影响。(2)在载荷与低硬度轧辊旋转同步变化的情况下进行的点蚀试验中，表面粗糙是由不起挤压作用的载荷降低位置的油膜破裂引起的，并观察到微裂纹和点蚀的连续发展。(3)证实了在积分传动比的情况下，研究了考虑表面粗糙度的两辊接触应力分析方法，并计算了应力集中，以阐明点蚀机理。(5)通过直齿圆柱齿轮的运转试验，得到了分别对应于油膜形成状态和动载荷的油膜电压与周向振动加速度之间的相关系数。对两次轧辊试验中采集的试验油进行了铁谱分析，研究了磨粒与运行过程的关系。观察到的颗粒类型几乎都是正常的摩擦磨损颗粒。

Two roller tests under variable loading pulsated by an oil pressure type pulsator were conducted, measuring the state of oil film formation by an electric resistance method, and the characteristics of partial elastohydrodynamic lubrication were investigated. Conclusions were as follows.(1) Effects of squeeze action on the state of oil film formation were recognized by existence of influence of load amplitude upon oil film formation and measuring result of cross-correlation between load cycle and oil film voltage.(2) In pitting tests which conducted under the synchronized load variation with the rotation of low hardness roller, the surface roughening was caused by break-down of oil film at the load decreasing position where the squeeze effect did not act, and micro-crackings and successive developments to pittings were observed.(3) It was confirmed that, in the case of integral drive ratio, almost complete improvement of oil film formation is caused by the increase in micro-geometrical conformity between two roller surfaces owing to replica impression of surface roughness, even under variable loading.(4) Method of analysis of contact stress between two-rollers considering the surface roughnesses was studied and stress concentrations can be calculated in order to clarify the mechanism of pitting.(5) By running tests of spur gears, cross corelation coefficients between the oil film voltage and the circumferential vibrating acceleration velocity, which correspond to the state of oil film formation and the dynamic load respectively, were calculated and these values were consistent with two-roller test results.(6) Analysis by ferrograph of test oils sampled during two roller tests was done and the relation between wear particles and running process were investigated. Types of particles which observed were almost normal rubbing wear particles.