PURPOSE: To make slab temp. constant and cast a slab of less sectional defects by patterning the spraying rates of cooling water for the process wherein the casting speed increases again after it lowers once, for each of the regions in secondary cooling of the slab.
CONSTITUTION: Molten steel 1 is teemed from a nozzle 2 into a mold 3, and with progression of casting, it is cooled with the cooling water sprayed from sprayers 41W4n. A slab 5 is drawn by drawing walls 6 at the approximately constant casting speed balanced with the rate of casting. During this time, the cooling water to be supplied to each sprayer is controlled with valves 71W7n, and the flow rates of the supply are monitored with flowmeters 81W8n. The amt. of the cooling water corresponding to the speed detection value detected with a speed detector 61 is calculated 9. At the time when the amt. of the cooling water changes, the respective valves are controlled by a flow rate controller 10 to control flow rates. As a result, the slab surface temp. is controlled constant, sectional defects are reduced and further the life of the rolls is extended.
KADOI KUNIO
HAMAGAMI KAZUHISA
SATOU KUNIHIRO
