| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress bend of a rail in a vertical direction without increasing cooling time.SOLUTION: A heat treatment device 3 performs forced cooling of a head part 11 and a leg part 13 of a rail 1 of high temperature which is subjected to hot rolling at temperature of an austenite region or higher temperature, or which is heated to the austenite region temperature or higher temperature. Then, the heat treatment device 3 calculates target temperature of a rear face of the leg part 13 at the time of transformation completion of the head part 11 using temperature of a front face of the head part 11 at the time of starting of forced cooling of the head part 11 in cooling of the leg part 13. Then, forced cooling of the leg part 13 is started after starting of forced cooling of the head part 11, and the forced cooling of the leg part 13 is performed so that the temperature of the rear face of the leg part 13 at the time of the transformation completion of the head part 11 becomes the target temperature.</p> |
