Bending Load Capacity Enhancement Using an Asymmetric Tooth Profile (1st Report, Influences of Pressure Angle on Tooth Root Stress and Bending Stiffness)

摘要

This research is to develop a new method to enhance the bending load capacity of gear tooth using asymmetric tooth profiles. For many power transmission devices operate in one direction, only one side of the tooth surfaces (the front of tooth) is in mesh. So the tooth is not necessary to be a symmetric form. The dimensions of the front and back profiles of the tooth could be designed individually. The back profile of the tooth that does not contact in running could be decided to decrease the maximum tensile stress at the root of tooth. Different standard pressure angles are used in the front and back profiles of an asymmetric tooth. Tooth root stress and bending stiffness of the asymmetrical tooth for several combinations of standard pressure angles were calculated by the use of finite element method. Based on the results of calculations, it is clarified that a larger standard pressure angle in the back profile of tooth makes the tooth root stress decrease remarkably and bending stiffness of tooth increase, but dose not change the load sharing ratio.