No abstract

Induction hardening of large bearing rings is a very challenging procedure due to the complex physical processes and their interactions, which need to be properly controlled to produce components meeting the imposed requirements of e.g. wind turbines. The different process parameters significantly alter the resulting microstructures and properties of such a bearing ring. The evolution of numerical simulations in the last decades allows the modelling of processes with a growing complexity. In this work, the challenges of a simulation model for induction surface hardening are shown and discussed. Besides the theoretical background of the interacting physical fields and a brief note about available software packages, the paper focusses on the elaboration of a necessary material database and on the specific problems of induction scan hardening processes for large bearing rings.

Heat treatment simulation of inductive surface hardening of large bearing rings is a challenging multi-physical task. Besides the determination of material and process parameters of induction heating, the quenching process must be modelled to obtain realistic results concerning surface hardening depth as well as information about residual stresses and distortions of the bearing rings. A common method to model quenching processes is to determine heat transfer coefficients for the specific process depending on component surface temperature. This method was used to characterize the shower cooling process using an aqueous polymer solution of a modified polyalkylene glycol (PAG) type. A specifically designed test set-up allowed to determine the heat transfer coefficients for different distances between shower and hot specimen as well as for different impingement angles of the fluid relative to gravitation. Additionally, the calculated heat transfer coefficients were checked and corrected by FEM simulations.