Study On The EHL Films Under Intermittent Motion

In this thesis, the EHL oil film in the intermittent motion was studiedexperimentally and theoretically.Firstly, an optical EHL test system developed in tribology laboratory was improved.In order to control the two servo motors to drive the steel ball and the glass disk, a PLCprogram was compiled. The oil supplied conditions in the experiments were dividedinto two states: fully supplied oil condition and starvation. The EHL films wereobserved in the intermittent motion in the two working conditions, respectively. Theoptical interferometry images were obtained in the experiments. Sliding-rolling ratio inthe experiments was0.0325. The experimental images were processed with a softwareMBI.For the fully supplied condition, the experimental results indicated that: in thestage of constant speed, the lower the entraining velocity was, the easier the elasticdeformation in the contact region would appear, the easier the horseshoe-shaped oilfilms would present, the earlier the exit constriction would appear at the same instant; inthe stages of deceleration and acceleration, the lower the entraining velocity was, theclearer the horseshoe-shaped oil films would be at the same instant; in the intermittentperiod, the lower the entraining velocity was, the fewer the oil entrapped would be inthe contact region, the more closely would the oil entrapped region near the exit, theslowlier the entrapped oil would move out of the contact region at the same instant.For the starved condition, the results compared with the fully supplied conditionindicated that: in the stages of constant speed, deceleration and acceleration, the centralfilm thickness in the starved condition was smaller than that in the fully suppliedcondition; the variations of the central film thickness in the stop period in the two oilsupplied conditions were similar: the central film thickness decreased at the end of thestop period. The minimum film thickness in the stages of constant speed, decelerationand acceleration was affected significantly by starvation.At last, the mathematical model of fully supplied oil lubrication was applied. Thenthe fully supplied oil lubrication was simulated in theory. The theoretical results were compared with the experimental results quantitatively. It was indicated that the trends ofvariation of oil films were consistent in the two results.