Research on an Optimized Hob to Increase the Bending Strength of Involute Gears by Changing the Root Fillet Profile

An optimized hob to increase the bending strength of involute gears by changing the root fillet profile is presented in this paper. The maximum bending stress which determines the service life of a gear in many applications depends on stress concentration caused by the gear root fillet. Better control of the root fillet can result in gears with higher bending strength. The optimised hob tool is a modification based on the standard hob tool, with constant normal base pitch, but a different pressure angle and module, which will generate a different gear root fillet area. The comparison analysis demonstrates that the gear generated by the optimised hob has higher bending strength than that generated by the common standard hob. For analysis and validation of results, three methods of predicting bending stress - ISO standard, three-dimensional tooth contact analysis (3D-TCA) method, and finite element analysis (FEA) are applied and discussed.