Appreciable improvements in oil film formation and surface durability of gears with the tooth profile modification.

Abstract

The influence of tooth profile modification on the surface durability of spur gears has been studied by using mirror-like finished gears with a high accuracy(=0.1μm Rmax, JIS M 00 class). In order to explain the effectiveness of tooth profile modification, the durations of the elastohydrodynamic lubrication condition (EHL) at the point of contact were measured by utilizing an electric resistance method. The results clearly showed that the duration of the EHL condition on gear pairs with tooth profile modification were improved, especially at the first and the last points of contact. Even though low hardness gears are used, it is necessary to modify the tooth profile in order to form the lubricating oil film between the meshing teeth, and to reduce the surface distress.