往复冲击对脂润滑成膜性能影响的试验研究

Experimental Study on Effect of Repeating Impact on Grease Film Formation

冲击现象广泛存在于工业链、滚动轴承等机械零部件中,严重的情况下会引起冲击磨损。为探究冲击载荷对脂润滑条件下成膜性能的影响,在点接触光干涉弹流试验台上对锂基脂润滑条件下的膜厚演化进行冲击试验研究。试验时钢球和玻璃盘的初始间隙设置为0,冲击载荷按三角波往复变化。结果发现:在第一个冲击周期内,接触区存在大块的增稠剂纤维团,该纤维团造成接触区内的脂膜凹陷;随着冲击周期的增加,接触区内的大块增稠剂纤维团消失,脂膜厚度逐渐降低,润滑状态进入到薄膜润滑状态,最后发生了表面损伤;在任何一个冲击周期内,中心膜厚和最小膜厚大部分的时间都呈现固定值;中心膜厚随着冲击周期数的增加而减小,最小膜厚在最初的100个周期内变化很小,此后逐渐降低,最后为0。

Impact phenomenon exists widely in mechanical components such as rolling element bearings and industrial chains,which can cause impact wear in the worst case.To investigate the effect of impact load on film formation under grease lubrication conditions,impact tests were carried out to study the grease film thickness evolution under lithium grease lubrication on a point contact optical interferometric test rig.During the experiment,the initial distance between the steel ball and the glass disk is set to zero and the load repeatedly varies in the form of a triangle wave.The results indicate that during the first impact period,there exists big lump of thickener fibers in the contact area,which results in an entrapment of the grease film.With the increase of the impact periods,the big lump thickener disappears,the film thickness is gradually reduced and lubrication state turns to be thin film lubrication.At last,surface damage occurs in the surfaces of both the steel ball and the glass disk.In each impact period,either central or minimum film thickness mainly exhibits a constant value.The central film thickness decreases with the increase of the impact periods.The minimum film thickness varies only slightly in the first 100 periods and gradually decreases to zero.