Patent ID: 7718018

Claim:
A method of controlled cooling of a steel plate using a cooling apparatus having a plurality of pairs of constraining rolls, each comprised of a top roll and a bottom roll, for constraining and conveying hot rolled steel plate, and groups of top and bottom surface nozzles having nozzles arranged in one line or a plurality of lines in a steel plate width direction and spraying a cooling medium to the top and bottom surfaces of the steel plate conveyed between pairs of constraining rolls adjoining each other in the front and back of the cooling apparatus in a steel plate conveyance direction, said method of cooling the steel plate characterized by: dividing a region of the steel plate cooled by the groups of top and bottom surface nozzles between pairs of constraining rolls into at least a spray impact part region, wherein said spray impact part region is beneath the top surface nozzles or directly above the bottom surface nozzles, and spray non-impact part regions, wherein said spray non-impact part regions are regions other than the spray impact part region, computing predicted temperature histories of the steel plate based on previously predicted heat transfer coefficients of the divided regions, and controlling the amounts of the sprayed cooling medium on the spray impact part region from the groups of top and bottom surface nozzles between the pairs of constraining rolls so that the top and bottom surface temperatures of the steel plate at the outlet side of the cooling apparatus given by computing predicted temperature histories of the steel plate become a target temperature.