EHL OF LARGE LENGTH/DIAMETER RATIO PROFILED NEEDLE ROLLER

摘要

Needle roller bearings are the cylindrical roller bearings, in which the ratio of roller length over diameter is larger than three. They are usually used for applications requiring exceptionally high load-supporting capability with very small section space, because their radial section area or the axial thickness is the smallest for all kind rolling bearings at the same basic dynamic load rating. They are usually crowned slightly toward their both ends to relieve high edge stress concentration caused by their finite line contacts or by misalignment or eccentric loads. The edge stresses will considerably shorten the bearing fatigue life. Based on the multi-level multi-integration (MLMI) technique, an effective, robust and stable algorithm was established by Sun et al [1, 2] with the aid of several developing numerical skills for the finite line contact EHL (FEHL). The Wymer and Cameron's [3] optical interferometric experiment results have been systematic and complete numerical simulated by this algorithm, the results agreed quite well with each other. It was found that the convergent solutions could be obtained under 1 GPa pressure for the rollers with less one length/diameter ratio, which means the length/width ratio of contact area was not larger than 70. For solving the FEHL calculation problems of large length/diameter ratio roller contacts at high pressure, and improving the efficiency of the numerical calculation of above MLMI method, Wu et al [4] investigated the influence of initial values setting on the calculated results. The convergent solutions could be gotten directly by numerical program itself when the optimized pressure and temperature initial values are used at the 1.45 GPa maximum pressure for the rollers length/diameter ratio reach to three.