METHOD FOR COOLING HOT STRIP BY PREFERENTIALLY INJECTING WATER ONTO LOWER PART OF THE STRIP

摘要

PURPOSE: A hot rolled strip cooling method is provided which is capable of solving problems of material defects due to detection error of coiling temperature by fundamentally preventing retention of cooling water on an upper part of hot rolled strip. CONSTITUTION: In a method for coiling the cooled hot rolled strip by cooling a hot rolled strip in a cooling facility comprising dynamic cooling part and feedback cooling part, the method for cooling the hot rolled strip by preferentially injecting water onto a lower part of the strip comprises the steps of setting the target coiling temperature range; injecting cooling water onto upper and lower parts of the hot rolled strip transferred by opening header of upper bank and lower bank of the dynamic cooling part; measuring coiling temperature of the hot rolled strip passing through the feedback cooling part following the dynamic cooling part; sequentially opening the header of the lower bank of the feedback cooling part and the header of the upper bank of the feedback cooling part in case that the measured coiling temperature values are higher than a target coiling temperature, thereby injecting cooling water onto the hot rolled strip so that measured coiling temperature values satisfy the target coiling temperature range; and sequentially closing the header of the upper bank of the feedback cooling part and the header of the lower bank of the feedback cooling part in case that the measured coiling temperature values are lower than the target coiling temperature so that measured coiling temperature values satisfy the target coiling temperature range.