| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the strain due to the shift-hardening of a long bar-like work, to unnecessitate a complicated setting operation for preventing the strain and to prevent the lowering of efficiency and the generation of defective product due to the setting operation. SOLUTION: The hardening surface of the work 10 is heated with a high-frequency induction in the axial direction in order by using a heating coil 20, and the heated surface is quickly cooled with a hardening liquid injected from cooling jackets 30A, 30B in order. The strain in this work 10 is detected during hardening with a sensor 40 arranged on the downstream side of the cooling jackets 30A, 30B. The injecting quantity from the cooling jackets 30A, 30B is controlled through a control part 50 during the hardening so as to obtain the injecting quantity distribution around the work axis needed to eliminate the detected strain.</p> |
