Studies On The Elastohydrodynamic Lubrication Films Under Rolling/Spinning Conditions

Elastohydrodynamic lubrication under spinning/rolling conditions has been investigated both experimentally and theoretically in this project.An optical test rig was revised for the present experimental studies. An mechanical unit, mainly for positioning and backing the steel ball against the galss disc, has been deliberately devised to facilitate rolling EHL with spinning.Using optical interferometry, the transport characteristics of an entrapped lubricant, which was formed by impacting the steel ball against the disc, was studied experimentally under spinning/rolling conditions. In the tests, different spinning levels were gained by changing the distance between the contact center and the disc rotation center. Experimental results show that the entrapped lubricant moves along the spinning direction, i.e., towards the side nearer to the disc rotation center. At the start stage, with larger spin ratios, there is faster discharge of the entrapped lubricants. However, at the late stage, faster discharge of entrapped lubricants occurs with lower spin levers..Steady state elastohydrodynamic lubrication (EHL) films were also studied experimentally under spinning/rolling conditions. The film thickness was obtained for different entrainment speeds, loads and spin ratios. Results show that with increasing speeds the film thickness increases, and the minimum side lobe film thickness has the largest speed index. The speed indices of the two side lobe film thicknesses are larger than that of the central film thickness. When the load is increased, the film thickness decreases and the film shape become more un-symmetrical. With increasing eccentricity, the influence of spin ratios on the film shape diminishes and the film shape becomes symmetrical and the minimum film thickness increases.Numerical calculations of circular contact EHL with spinning have been carried out in the study. The film thickness and pressure were obtained for different entrainment speeds, loads and spin ratios. The numerical results show good correlation with experiments qualitatively.