Patent ID: 7253381
Filing Date: 2007-08-07
Classification: C21D,H05B,Y02P

Abstract:
1. A method of heating a workpiece comprising the steps of: placing the workpiece at least partially within an induction coil to magnetically couple the workpiece with a first ac magnetic field generated by the flow of a first ac current in the induction coil to inductively heat the workpiece; forming at least one magnetic circuit from the workpiece and at least one generally C-shaped inductor; and supplying a second ac current in at least one solenoidal coil wound around a section of the at least one generally C-shaped inductor to magnetically couple the at least one magnetic circuit with a second ac magnetic field generated by the flow of a second ac current in the solenoidal coil to heat the workpiece, the frequency of the first ac current greater than the frequency of the second ac current.