| 摘要 |
PURPOSE:To perform a hardening test with reliability by sandwiching a hot- rolled steel sheet with the respective cooling surfaces of a pair of plural cooling boxes to cool locally the steel sheet so that the steel sheet positioned in the intermediate part of the cooling boxes is cooled by heat conduction and the cooling rate is thus changed continuously. CONSTITUTION:Two sets a pair of cooling boxes 4A, B, 5A, B of which the cooling faces are positioned oppositely to each other are disposed at suitable intervals and are moved by movable mechanisms 6A, B, 7A, B such as air cylinders so that a hot-rolled steel sheet 1 is sandwiched by the respective cooling surfaces P. A cooling medium C is ejected to the inside of the boxes 4A, B, 5A, B and the rolling surfaces of the sheet 1 facing the surfaces P are cooled. The parts of the sheet 1 which are not sandwiched by the boxes 4A, B, 5A, B are kept air cooled, and the cooling rate is continuously changed by the heat conduction in the rolling direction of the sheet 1. |
