Numerical simulation study on integral induction heating of backup roll

Abstract

A finite element model (FEM) of the electromagnetic-thermal coupling is developed to study the integral induction heating of the backup roll. The method of calling different B–H curves of the material at different temperature moments is proposed to consider the change of the relative permeability of the backup roll in the temperature rise process. The magneto-thermal two-way coupling simulation of backup rolls was carried out in ANSYS with consideration of the heating power or current change, and the field test verifies the result. The influence of critical heating process parameters, such as the effective heating length of the coil, the chamfer radial, and the diameter of the backup roll on the temperature distribution, is studied. The results reflect that the length of the induction coil above the roll on one side should be controlled between 100 mm and 200 mm. Temperature near the end of the backup roll increases significantly when the length of one side of the coil exceeds 200 mm. The coils with the same diameter can heat the rolls with different diameters. The diameter difference between the coil to the roll should control around 200 mm to ensure uniformity of temperature distribution along the axial direction. The current value needs to be increased to confirm that the temperature near the end of the roll meets the requirement when the diameter difference between the coil and the roll exceeds 200 mm. The results provide a possibility for pre-evaluating the rationality of induction heating processes in production.