Abstract
This paper presents a study on residual stresses and hardened layers of gears due to dual frequency induction hardening (using both high-and low-frequency heat sources). Temperatures during a single frequency induction heating process of the gear were calculated by FEM electromagnetic field analysis and heat conduction analysis methods, considering changes of the magnetic permeability and the resistivity with the temperature, and were measured using thermocouples. An electromagnetic field analysis, a heat conduction analysis and an elastic-plastic stress analysis, considering changes of the magnetic permeability, the resistivity, the thermal expansion coefficient and the yield stress with the temperature, during the single frequency and the dual frequency induction hardening process of the gear were carried out by the three-dimensional finite-element method (3D-FEM), and then residual stresses and hardened layers were obtained. The effects of the electric power and the frequency on the temperature and the stress change during the induction hardening process, the residual stress and the hardened layer were determined.
