Patent ID: 8454767
Filing Date: 2013-06-04
Classification: F16D

Abstract:
1. A heat treatment method for forming hardened layers in roller guide surfaces of an outer joint member, the heat treatment method comprising: performing mobile quenching by moving a high-frequency induction heating coil in an axial direction relative to the outer joint member comprising track grooves that are formed at three positions of an inner periphery of the outer joint member, each of the track grooves comprising: the roller guide surfaces facing each other in a circumferential direction of the outer joint member; and a larger radially-inner portion provided between the roller guide surfaces; providing heating-suppressing portions for the larger radially-inner portions in the high-frequency induction heating coil by arranging magnetic field line cut-out bodies for cutting out magnetic field lines generated through the high-frequency induction heating coil at positions of the high-frequency induction heating coil that are opposed to the larger radially-inner portions; and setting a section of each of the larger radially-inner portions corresponding to a boot mounting portion at least a center portion in the circumferential direction of the outer joint member to be an unquenched portion.