| 摘要 |
<p>PROBLEM TO BE SOLVED: To obviate the necessity of the complicated structure in a hardening device and the large size of a part inserted into a bottomed cylindrical work of the hardening device by hardening the inner peripheral surface to near the topmost part of the bottomed cylindrical work, at the time of shift-hardening the inner peripheral surface of the bottomed cylindrical work with the opening hole side down from the lower part to the upper part. SOLUTION: At the point of time when an induction heating coil 20 for heating the inner peripheral surface of the bottomed cylindrical work 10 reaches near the topmost part of the bottomed cylindrical work 10, the jetting quantity of the hardening liquid 50 jetted from a cooling jacket 30 arranged below the induction heating coil 20 is increased by two times. A part of the jetting hardening liquid 50 is flowed upward along the inner peripheral surface of the bottomed cylindrical work 10, and the hardening liquid 50 is supplied to the last heating part of the inner peripheral surface with the induction heating coil 20.</p> |
