Patent ID: 8282747
Filing Date: 2012-10-09
Classification: B21B,C21D

Abstract:
1. A cooling method of steel plate which cools a hot rolled steel plate, while conveying it in one direction, by supplying cooling water from nozzles arranged at the top and bottom in a cooling apparatus, said cooling method of steel plate characterized by: dividing said steel plate into a front end region, a front part region, and a center part region from a head side in the conveyance direction of said steel plate and dividing said cooling apparatus into a front stage part and a rear stage part in the conveyance direction of said steel plate, at said front stage part of said cooling apparatus, not spraying any cooling water while said front end region of said steel plate is passing, spraying by successively increasing amount of cooling water from 80 to 95 vol % of a standard water density when said front part region passes so that said amount of cooling water becomes said standard water density when the boundary of said front part region and said center part region arrives, wherein said standard water density is the amount of water per unit area and unit time sprayed to the center part region of the steel plate; continuing spraying by said standard water density while the center part region is passing, and, at said rear stage part of said cooling apparatus, spraying by an amount of cooling water of 80 to 95 vol % of the standard water density while said front end region of said steel plate is passing, successively increasing amount of cooling water from 80 to 95 vol % of said standard water density when said front part region passes so that said amount of cooling water becomes said standard water density when the boundary of said front part region and said center part region arrives, continuing spraying by said standard water density while the center part region is passing, and wherein said front end region is a region of 0.5 to 2 meters from head side of the steel plate towards center part side in said steel plate length direction, said front part region is a region of 4 to 10 meters from the boundary of the front end region and the front part region towards center part side in said steel plate length direction, and said center part region is a center part side region in the steel plate length direction from the boundary of the front part region and the center part region.