| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a heat treatment method which can not only increase an amount of retained austenite on a surface layer part of a raceway surface, but also can inhibit the increase of an amount of retained austenite on a part except the surface layer part. <P>SOLUTION: This heat treatment method includes sequentially induction-heating an inner ring 5 by supplying a high-frequency power having a frequency with a fixed cycle to a high-frequency heating coil 9 having a first heating part 12 and a second heating part 13 which have different diameters from each other. The heat treatment method also includes: a first step of firstly, uniformly heating the whole inner ring 5 to the transformation point A1 or higher with the first heating part 12 which has a larger clearance C1 between the inner ring 5 and the first heating part; and a second step of subsequently heating only the surface layer part of a raceway 4 of the inner ring to a higher temperature with the second heating part 13 which has a smaller clearance C2 between the raceway 4 of the inner ring and the second heating part. The above problem can be solved by the above heat treatment method. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
