| 摘要 |
PURPOSE:To make the lengthwise temp. distribution of a steel plate after cooling uniform and prevent variances in mechanical characteristic values and deformations from occuring in the steel plate by changing the cooling start time with the lengthwise direction of the steel plate at the time of cooling the hot rolled steel plate. CONSTITUTION:At the time of performing on-line accelerated cooling of a thick- walled steel plate which is hot rolled with finishing mills 1, it is cooled in a cooling zone 3 which is provided with plural headers 4 provided with cooling water jetting nozzles vertically opposedly in the direction of a pass line 2. In this case, the predetermined length at the trailing end of the steel plate of a low temp. is left outside of the cooling zone, thence the conveying is started at a predetermined speed. Cooling water is jetted by the headers to the steel plate except the leading end part of a low temp. in the lengthwise direction; at the same time, the jetting is successively progressed from the unjetting header near the same to the adjacent unjetting headers in the conveying direction of the steel plate. After the point where the leading end position of the steel plate and the header position at the jetting start coincide, the remaining unjetting headers are jetted, whereby the entire part of the steel plate having the low-temp. part at the leading and trailing end parts is cooled to a uniform temp. |
