Patent ID: 6648995
Filing Date: 2003-11-18
Classification: C21D,Y02P,Y10S,Y10T

Abstract:
A method of hardening a workpiece having a hole, comprising the steps of:loading an inductive member covered with an electrically insulating member into a hole defined in a workpiece; effecting high-frequency induction hardening on the workpiece while the inductive member is being held in position by a holder member made of an electrically conductive material which is disposed in an opening in an end of the hole; simultaneously, during application of said inducting hardening, generating a magnetic field from the inductive member loaded in the hole to produce a treated layer adjacent said hole, wherein a radial distance between an axial line of said hole and a surface of said treated layer progressively increases in an axial direction from a position inside of said hole toward openings in respective ends of the hole; and quenching said workpiece and said hole by cooling said treated layer to produce a hardened layer.