Method of Induction Hardening
AssigneeHonda Motor Co., Ltd.
InventorsKazuo Minemura, Yukihiro Chikazawa
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Abstract
Long work of Fe based alloy while being rotated at a given rotation speed under the action of rotating chucks is heated by high-frequency heating coil to thereby accomplish the heating step. In the first cooling step after termination of the heating, the long work while having its rotation speed increased is brought into contact with first to fourth correction rollers, and in that state is cooled so as to fall within a temperature range of Pf temperature or below to over Ms temperature. The time spent in the cooling preferably ranges from 5 to 10 sec. In the subsequent second cooling step, the rotation speed of the long work is reduced, preferably so as to be equal to that at the heating, and cooling of the long work is continued.
Claims4
An induction hardening method for hardening a long work containing an Fe-based alloy, wherein said long work is heated by high-frequency induction heating while being rotated, and when said long work is distorted in the hardening, a correction roller is brought into contact with said long work to correct the distortion,
- said method comprising:
- a heating step of heating said long work by said high-frequency induction heating to a first temperature range, within which an austenite is formed, while rotating said long work at a first rotational speed;
- a first cooling step of cooling said long work to a second temperature range of higher than the martensite start temperature and at most the pearlite finish temperature while rotating said long work at a second rotational speed higher than said first rotational speed;
- and
- a second cooling step of further cooling said long work having a temperature within said second temperature range while rotating said long work at a third rotational speed lower than said second rotational speed.
Dependencies are inferred from the claim text.