Patent ID: 8567225

Claim:
A method of manufacturing a bent member having a bent portion which is bent three-dimensionally intermittently or continuously in its lengthwise direction comprising supporting a hollow elongated metal material having a closed transverse cross-sectional shape at a first position while feeding it in its lengthwise direction, forming a high temperature portion which moves in the axial direction of the metal material by performing induction heating of the metal material at a second position located downstream of the first position in the feed direction of the metal material using an induction heating coil and cooling the metal material at a third position located downstream of the second position in the feed direction of the metal material, and three-dimensionally varying the position of a gripping mechanism which grips the metal material in a region downstream of the third position in the feed direction of the metal material to apply a bending moment to the high temperature portion, characterized in that when the wall thickness of the metal material is at most 2.0 mm, the feed speed of the metal material is made 5-150 mm/sec, an induction heating coil having 1 winding is used as the induction heating coil, and an alternating current at 5-100 kHz is applied to the induction heating coil.