Study on induction heating of workpiece before gear rolling process with different coil structures

The temperature distribution of heated workpiece has a great impact on the subsequent gear rolling process. To get a satisfied temperature distribution, longitudinal magnetic flux (LMF) coil and transverse magnetic flux (TMF) coil were designed. The influences of current density and current frequency on the heating efficiency and the temperature distribution of the workpiece corresponding to two coil structures were investigated by establishing an induction heating model combing the coupling of electromagnetic and thermal fields and the rotary motion of the workpiece. In addition, an induction heating experiment was conducted to verify the model. From the numerical results, a conclusion can be made that compared with TMF coil, the LMF coil can reduce the inner hole temperature and improve the heating efficiency. With proper current density and current frequency, the workpiece heated by LMF coil can obtain a better temperature distribution than that heated by TMF coil.