Simulation of Induction Surface Hardening of Large Bearing Rings Using Volume Heat Sources – Part 1

Abstract Induction hardening of large bearing rings made of steel is a very challenging task. The four interacting physical fields electromagnetics, temperature, phase transformations and mechanics combined with the highly nonlinear material properties of typical steel grades make it difficult to produce components with the desired hardened layer while maintaining dimensional stability. Especially in small-batch or single-unit production, as it is often the case for large bearing rings, the process parameters are mostly chosen based on experience. Numerical simulations taking into account all physical fields and the relevant interactions are up to now not feasible for large bearing rings due to their high effort. Therefore, a new approach has been developed which replaces the electromagnetic field and its interactions by a moving volume heat source acting as a boundary condition for the temperature field. The heat source parameters are determined based on in-situ temperature measurements in case of a moving inductor. In the following part 2, the thermal simulations using the volume heat sources are complemented by phase transformations to deepen process understanding and allow for process improvements. The simulation results are validated by metallographic images and hardness tests.