| 摘要 |
<p>PURPOSE: To execute uniform hardening without uneven hardening by accurately positioning a hardening head in the inner surface of a cylindrical body while shifting a tapered member vertically moved in the axial direction of the cylindrical body, at the time of executing induction hardening of the inner surface of the steel-made cylindrical body. CONSTITUTION: The hardening head 24 having an induction heating coil 33 is inserted into the inner surface 30a of the steel-made cylindrical body 30, and a driving rod 23 is shifted downward, and a positional block 38 is pressed and uniformly expanded to the outer part in the diameter direction in the inner surface 30a of the cylindrical body with an expanded cone at the lower end of the driving rod 23 and abutted on the inner surface 30a of the cylindrical body. A facing part 34 of the inner surface 30a of the cylindrical body is heated to high temp. by Joule's heat with the induction current conducted in a heat input part 33a of the induction heating coil laid on a flange part 32a at the tip part of the hardening head 24. Therefore, the conduction of the induction current is switched off and the rapid cooling is executed with the cooling water W to accurately harden the prescribed position 34 of the inner surface 30a of cylindrical body.</p> |
