Residual-stress-driven deformation of thin-walled ring gears during hobbing

Abstract

Thin-walled ring gears are prone to hobbing-induced distortion because material removal redistributes body residual stress (BRS) and introduces machining-induced residual stress (MIRS). This study distinguishes BRS and MIRS and establishes a coupled finite element method (FEM) workflow for normalized 18CrNiMo7-6 ring gears by combining AdvantEdge cutting simulation with ANSYS material-removal analysis. Initial BRS was evaluated using strain energy density, and residual-stress evolution during hobbing was examined under different hobbing-cutter rotational speeds and axial feed rates. Cutting power was used to assess the cutting-load input, whereas post-hobbing deformation measurements were used to evaluate the endpoint prediction of the coupled model. The results show that residual stress is concentrated near the tooth root and that a moderate increase in rotational speed or axial feed rate can reduce tensile surface residual stress within the tested parameter range. The through-thickness machining position also strongly affects radial deformation. These findings provide a basis for controlling hobbing distortion in thin-walled ring gears through process-parameter selection and blank-position planning.