| 摘要 |
<p>PURPOSE:To surely prevent bending at top end in the control of the top end bending in which the lower face of the top end of a rolling material is cooled before roll. CONSTITUTION:In a hot rolling line which is provided with a bottom cooling device on the entrance side of a rolling mill, and in the performance of the top end bending control in which the lower face of the top end of the rolling material is cooled before rolling, (1) a bottom cooling header is divided to plural numbers in the width direction, and the cooling area in the width direction is made vaiable; (2) the cooling width of the lower face of the top end part in the width direction is made not more than the plate width (Wp), simultaneously the lower limit value (Wmin) for the cooling width in the width direction, for which the generation of bending can be prevented over the entire length in the plate width, is determined, and the lower face is cooled as not less than the lower limit value; (3) the time for cooling the lower face is determined, in consideration of the reduction of cooling area against the cooling time of the entire width, from the cooling time necessary in the case of cooling over the entire length in the width direction.</p> |
