INDUCTION HARDENING METHOD, DEVICE THEREFOR AND HARDENED PRODUCT THEREFROM

摘要

PROBLEM TO BE SOLVED: To execute a hardening which can improve both characteristics of lubricity and wear resistance. SOLUTION: A hardening head 23 is shifted by a prescribed interval from the upper part toward the lower part of a cylinder bore 14a by driving a Z-axis motor and an induction hardening is applied in the hardening order of forming every one line in the hardening part. The hardening process of one line is completed within about 0.5sec and the hardening head is shifted to the next position within about 0.5sec. In the case of forming five lines of the annular hardening part, it takes about 5sec. to execute the hardening to the inner surface of one cylinder bore. Cooling waste W for cooling the heating position in the cylinder bore 14a is supplied from the reverse direction opposite to the above hardening order direction. The cooling water is always spouted so that the spouted flow A from cooling water injecting holes 77b in a cooling water ejecting nozzle 77 at the lower part of the cylinder bore 14a prepositioned to be fixed at a fixed position is ejected from the lower part toward the upper part along the inner wall surface of the cylinder bore 4a.