| 摘要 |
<p>PROBLEM TO BE SOLVED: To execute hardening for a block with small strains even if an induction heating coil with a simple shape is used, after the completion of a 1st stage in which the bottom wall is subjected to stationary hardening, by executing a 2nd stage in which a pair of side walls are successively subjected to stationary hardening one by one. SOLUTION: This hardening method contains a 1st stage in which a bottom wall elongating in a prescribed direction is subjected to stationary hardening and a 2nd stage in which, upon the end of the 1st stage, a pair of side walls are successively subjected to stationary hardening one by one, and preferably contains a 3rd stage in which a pair of side walls are simultaneously subjected to stationary hardening instead of the 2nd stage or a 4th stage in which either side wall of the pair of side walls and the bottom wall are simultaneously subjected to stationary hardening and a 5th stage in which the remaining side wall is subjected to stationary hardening instead of the 1st stage and the 2nd stage. Though the shape of the induction heating coil to be used in the 4th stage is made to be the slightly complicated one, the productivity improves. A groove 20 for bearing sliding formed on a block 10 has a bottom wall 22 elongating in the direction of the arrow A and a pair of side walls 24 and 26 having recessed parts 24a and 26b.</p> |
