PROBLEM TO BE SOLVED: To provide a method of and a device for cooling the back surface of a hot-rolled steel strip by which the back surface of the hot-rolled steel strip is cooled with a large quantity of water and at high cooling rate even when they are places where intervals between conveying table rollers such as a run out table are narrow, on a manufacturing line of the hot-rolled steel strip.;SOLUTION: A plurality of flat spray nozzles 2 are arranged in the width direction between the conveying table rollers 1, and all the positions in the width direction of the back surface of the hot-rolled steel strip 10 are made so as to pass through the collision area 2b of the cooling water 2a from the flat spray nozzles 2 one or more times and also the ratio D/Pw of the outside diameter D of the flat spray nozzle 2 to a mounting pitch Pw in the width direction of the flat spray nozzle 2 is taken as ≤0.5. The axis of the collision part 2b to the hot rolled steel strip 10 of the cooling water 2a from the flat spray nozzle 2 is inclined 45-70° to the width direction of the steel strip and the distance from the tip of the flat spray nozzle 2 to the hot-rolled steel strip 10 is taken as 50 mm to less than the radius of the table roller 2.;COPYRIGHT: (C)2010,JPO&INPIT
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