Prediction of the wear pattern in worm gears

Abstract

The paper is concerned with the prediction of the detailed pattern of wear, which takes place on the teeth of worm gear wheels under lubricated conditions. The wear model adopted is based on a published empirical standard, which includes the effect of fluid film thickness in the form of a lambda ratio parameter (film thickness/RMS roughness). The analysis is based upon a full elastohydrodynamic lubrication (EHL) solution in which the detailed distribution of wear on the tooth surfaces during meshing is summed to determine the calculated wear per meshing cycle. The calculated wear is then used to modify the unloaded geometry of the tooth surfaces, and the EHL and wear calculations are repeated in a series of “wear steps”. Results are presented that show the way in which the pattern of wear develops to produce the wear scars seen on the teeth of gears in practice.