| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the pitch error after hardening even in the case of being a carbon steel-made or alloy steel-made ball thread, or cut thread or rolled thread, as a work. SOLUTION: A high frequency induction hardening apparatus 100 is provided with a hardening mechanism 110, a temp. measuring instrument 180 fitted to this mechanism, a transporting mechanism 130 for transporting the hardening mechanism 110 along the work W and a turning and elongation detecting mechanism 150 for turning the work W and also, detecting the elongation of the work W, etc., are provided. In a hardening control method, by which for reducing the pitch error after high frequency induction hardening of the ball thread as the transported and hardened work W, the extension of the whole length of the work W during transporting and hardening, is measured and the heating quantity to the portion in the work W hardened thereafter, is corrected by utilizing the data of the measured result of this elongation, the temp. before hardening the work W and the remaining temp. at the portion just after hardening the work W, are measured. The heating quantity of the work W is further corrected so as to reduce the pitch error by utilizing the data of measured temp. difference, and to the portion in the work W hardened thereafter, the transportation and the hardening based on this correction, are progressed.</p> |
