| 摘要 |
<p>PURPOSE:To allow the simultaneous hardening of a prescribed position even if a work expands by moving a high-frequency heating coil toward a moving center pin in correspondence to the axial elongation of the work. CONSTITUTION:A high-frequency current is passed to heating coils 31, 32, 33 while the work 10 is kept rotated around an axis 23. The work 10 is heated by the induced current induced in circular cylindrical parts 11, 12, 13 and elongates toward the movable center pin 22. The heating coils 31, 32, 33 are moved toward the movable center pin 22 by commanding moving devices 41, 42, 43 from a heating coil position controller 46 or by other methods in correspondence thereto. The respective centers of the heating coils 31 to 33 are aligned to the centers in the axial 23 direction of the hardened layers to be formed on the peripheral surfaces 11a to 13a of the work 10. The hardened layers are formed in the prescribed positions on the peripheral surfaces 11a to 13a even if the work 10 expands.</p> |
