| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat treatment method of an outer member in a bearing device for a wheel capable of forming a consistently hardened layer by induction hardening. SOLUTION: A heating unit 21 integrally has annular high frequency heating coils 21a, 21b corresponding to double-row outer rolling surfaces 2a, 2b, and a coil 21c for a shoulder arranged therebetween. The difference between outside diameters Dc1, Dc2 is set to be identical to the difference between groove diameters d1, d2. The outside diameter Dc2 of the induction heating coil 21b corresponding to the outer rolling surface 2b on the inner side is set to be smaller than the inside diameter ds of a shoulder 18. When the heating unit 21 is inserted from the outer side of an outer member 2, and the axis of the heating unit 21 is matched, the induction heating coils 21a, 21b are arranged facing the double-row outer rolling surfaces 2a, 2b and conducted, the heating unit 21 is turned around the axis, and simultaneously hardened by cooling water 25 ejected from a cooling nozzle 22 to continuously form a predetermined hardened layer 14. COPYRIGHT: (C)2008,JPO&INPIT
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