Study on the influence of structural parameters of flexspline tooth rings on the maximum load stress in harmonic drives

ObjectiveIn order to reveal the influence of tooth ring structural parameters on the maximum load stress under the load and provide theoretical guidance for the strength design of tooth rings, a calculation method of load stress of flexspline tooth rings was proposed.MethodsAccording to the load of the tooth in the meshing zone of the long axis of the flexspline under load conditions, the tooth was equivalent to a variable section beam model considering the rounding of the tooth dedendum. The additional bending stress generated by the maximum meshing force between the teeth at the cogging under different load torques was studied, and the expression of the maximum load stress of tooth rings was obtained by superimposing it with the highest assembly stress. The influence of parameters such as the tooth ring thickness, the fillet radius at tooth dedendum and the groove width ratio on the maximum load stress was analyzed. Finite element models were established to numerically verify the theoretical solutions of assembly and load stresses.ResultsThe results show that the maximum load stress of the tooth ring decreases sharply and then increases slowly with the tooth ring thickness, and the optimal thickness coefficients of the tooth ring increase with the increase of loads. The optimal fillet radius of the flexspline tooth ring is 0.6<italic>m</italic>-0.7<italic>m</italic>. The optimal groove width ratio decreases with the increase of the load torque.