Induction heating apparatus, and induction heating method of gear and stepped axis

摘要

An object of the present invention is to provide an induction heater and an induction heating method capable of heating by induction a work in which a gear portion and a shaft are integrated. An induction heater for a gear portion and a stepped shaft is arranged in such a manner that a first heating coil (annular coil) surrounds the gear portion and that a second heating coil (linear coil) faces the stepped shaft in an axial direction. Alternating currents of different frequencies are supplied to the first heating coil 1 and the second heating coil. Further, a part of the second heating coil is arranged so as to come opposite a boundary between the gear portion and the stepped shaft and thereby connecting a hardened pattern of the gear portion by the first heating coil and a hardened pattern of the stepped shaft by the second heating coil.