Patent ID: 8404062

Claim:
A cooling method for a hot strip comprising using a first cooling header group including nozzles for injecting rod-like flows of a coolant diagonally toward a downstream side of an upper surface of the strip to impinge against said surface, and a second cooling header group including nozzles for injecting the rod-like flows of the coolant diagonally toward an upstream side of the upper surface of the strip to impinge against said surface, the first cooling header group and the second cooling header group being oppositely arranged with respect to a strip conveying direction: the injection rate of the rod-like flow of coolant which impinges against the strip is 8 m/sec or higher and supplying the coolant to the strip with a water amount density of 2.0 m 3 /m 2 min or higher from the nozzles; the second cooling header group being positioned sufficiently away from the first cooling header group in the strip conveying direction to define a residual region on the strip having a distance L in the downstream direction between the position at which the most downstream rod-like flows of coolant from the first cooling header group contact the strip and the positions at which the most upstream rod-like flows of coolant from the second cooling header group contact the strip, and said distance L is not more than 1.5 m, the rod-like coolant of at least some of the rod-like flows is injected at an angle so that 10% to 35% of a velocity component of the rod-like flow in the injection direction becomes the velocity component directed outward of the hot strip in a width direction, and adjusting a length of a cooling zone by independently switching ON-OFF each of the cooling headers of the first cooling header group and the second cooling header group.