| 摘要 |
<p>PURPOSE:To obtain the controller for cooling a hot-rolled steel sheet capable of uniformizing the cooling rates on the upper and lower faces of the hot steel sheet by providing a means for controlling the amt. of cooling water to be sprayed from a nozzle arranged on the upper face so that the temp. difference between the upper and lower faces is kept at a value lower than the predetermined allowable value. CONSTITUTION:The relation between the amt. of cooling water to be sprayed from each nozzle 7c arranged on the upper and lower faces of a hot steel sheet 1 and the heat transfer rate of the sheet 1 is obtained by first and second arithmetic means. The amt. of cooling water to be sprayed from the nozzle 7c arranged on the upper face is controlled by a cooling water control means based on the obtained relation with the cooling water amt. from the nozzle 7c on the lower face as a reference. At the same time, the amts. of water to be sprayed on the upper and lower faces are controlled so that the temp. difference between the upper and lower faces of the sheet 1 is kept at a value lower than the predetermined allowable value. Accordingly, since the temp. difference between the upper and lower faces of the sheet 1 at the time of cooling is kept at a value lower than the predetermined value in this way, the cooling rate of the sheet is uniformized, deformation in cooling is prevented, and a quality symmetrical in the thickness direction is obtained.</p> |
