Stress Analysis of Cup Type Strain Wave Gearing : 2nd Report : Effect by the Contact with Circular Spline

Abstract

In the strain wave gearing, the flexspline is a thin-wall cylinder with external teeth, the circular spline is a rigid ring with internal teeth, and the wave generator is an oval bearing. The main purpose of this study is the numerical evaluation of the stress in the flexspline which is the key element for the motion transmission in this components. When 'the flexspline is deformed into an elliptical shape by repeated load from the wave generator, the fatigue strength at the root of the tooth in the flexspline is a serious problem. The cup type strain wave gearing is modeled for FEM analysis. In the three dimensional field, the work ball of bearing and the oil film are modeled. And 16 nodes element is used as the contact element to consider the contact problem between the teeth of flexspline and circular spline. Deformation shape of the flexspline, various stress distribution at the root of tooth in the flexspline, and load of the bearing ball are calculated. The results show good agreement with experimental measurement qualitatively and quantitatively.