线接触零卷吸弹流条件下的急停分析

Analyses of the Zero-entrainment Line Contact EHL at Sudden Stop

对滚珠丝杠、滚珠蜗杆、无保持架滚柱轴承中常见的零卷吸状态下的急停问题进行热弹性流体动力润滑模拟;采用不同的初始零卷吸表面速度和急停时间,探讨线接触零卷吸条件下发生急停时油膜压力、膜厚和温升的变化。结果表明:相同急停时间下,中心压力和中心膜厚在急停过程中逐渐增大,随初始零卷吸表面速度的增加而轻微减小;初始零卷吸表面速度相同时,中心压力和中心膜厚均随急停时间的增加而逐渐增加;油膜的温度峰在急停前期缓慢下降,而在急停后期急剧下降。零卷吸工况下的急停会造成运动过程中接触区中心压力的急剧增加,会导致两接触固体间的应力远超过材料的屈服极限,使两接触表面会发生塑性变形,造成表面损伤。

Numerical analyses about sudden stop of zero-entrainment line contact elastohydrodynamic lubrication(EHL),which is common in ball screw,ball worm and roller bearing without cage,was carried out to investigate the pressure,the film thickness and the temperature of the oil film under different initial zero-entrainment surface velocities and sudden-stop times.The results show that under the same sudden stop time,the central pressure and central film thickness are increased in the process of the sudden stop,and decreased slightly when initial zero-entrainment surface velocity is increased.The central pressure and central film thickness are increased as the sudden-stop time increases if the initial zero-entrainment surface velocity is identical.The temperature peak of the oil film is decreased slowly at first but rapidly decreased at the last stage of the sudden stop.Sudden stop of zero-entrainment causes the central pressure increase dramatically,therefore,plastic deformation happens in both two surfaces because stress surpasses the yield limit of steel,which leads to surface damage.