Wear life prediction method of crowned double helical gear drive in point contact mixed elastohydrodynamic lubrication

Abstract

Double helical gears are widely applied in the aviation, marine and energy equipment, and generally required to be modified as the crowned since the machining error and assembling error of the gear drive are inevitable. The crowned gears usually operate in point contact mixed elastohydrodynamic lubrication (EHL), and adhesive wear has been one of the most prominent problems, but few previous researches were focused on this problem. In this work, a wear life prediction model of crowned double helical gears in point contact mixed EHL is proposed. The tooth profiles of the crowned gears are obtained according to the generating principle, and the load is attained in consideration of multi-tooth pairs contact. The contact pressure is derived from Hertzian elastic contact theory and load sharing concept, and the sliding distance is determined by a generalized model. Then, the wear rate in point contact mixed EHL is evaluated by extending the Archard theory to lubricated case, and the extended Archard's wear model is used to formulate the gear tooth wear. Moreover, the wear life prediction model which takes account of rotation speed and input torque is established, and the influences of surface roughness and crowned amount on the wear life of the crowned gears are further studied. Results show that surface roughness has a great influence on the wear life at different rotational speeds, while input torque has a great influence on the wear life at different crowned amount. It indicates that the wear life of the crowned double helical gears can be improved by reasonable matching lubrication, modification and working parameters.