2018 Volume 104 Issue 11 Pages 699-707
The applicability of the finite element method coupled with electromagnetic field analysis and heat conduction analysis to optimization of induction heating of a bearing raceway was assessed. In order to obtain temperature uniformity in a heated raceway, precise design of the coil arrangement and heating schedule are required. It is important to know how the internal temperature changes with time for the development stage.
The one-dimensional skin current model predicts that the temperature difference between the outer and inner surfaces decreases and that the temperature becomes uniform as the heating region moves inward when the outer surface temperature nears the Curie point. This phenomenon was reproduced in simulations and experiments for a ring sample, but it depended on the balance between the thickness of the ring and the penetration depth of the electromagnetic field. It is necessary to set an appropriate rate of temperature increase and frequency for the power source according to the thickness of ring.
High accuracy analysis was possible by using temperature-dependent B-H characteristics when a heated ring was in the ferromagnetic state. However, in the paramagnetic state, the agreement between simulation and experiment became worse. This may be due to the high rate of temperature increase used in this study, which suggests that the shift in the transformation point to high temperature must be taken into account.
