Tooth Surface Stress and Flash Temperature Analysis with Trochoid Interference of Gears

Abstract

Typical damage to gears is pitting and breakage of teeth, so it was traditionally designed based on these two damage and tooth surface shape design was done to avoid edge contact. However, in recent years, a design method that minimizes the tooth surface modification amount to maximize the load capacity and a tooth surface modification method that can secure a contact region even in a low load region are adopted. However, damage due to trochoid interference occurs outside the geometric meshing range and can’t be calculated by the strength calculation formula (ex. gear strength standard). And, with such a tooth surface modification, since tooth edge contact is accompanied in a high load region, it is necessary to consider edge contact stress analysis of the tooth due to trochoid interference. For this reason, this software (CT-FEM Opera iii [1]) adopts the finite element method (FEM) as a method capable of edge contact analysis and analyzes it. With the occurrence of edge contact, a large stress is generated in that portion and the flash temperature becomes high temperature, so temperature analysis of this portion is important. In the stress analysis of the teeth, it is necessary to analyze considering the tooth surface modification, the tooth profile error, the pitch error, and the posture error of the axis in consideration of tooth deformation and load sharing. At the time of engagement of the teeth, the curvature of the tooth profile, the sliding speed, the tooth surface roughness and the lubricant greatly change the friction coefficient and the oil film thickness depending on the tooth surface position. Therefore, tooth surface stress, edge contact stress, and flash temperature are also greatly affected. In this paper, the damaged picture of the experiment gear and the edge contact stress analysis result are shown, and they are in good agreement. And the analysis results of flash temperature, friction coefficient distribution, oil film thickness, power loss, transmission error, and tooth bending stress are shown.