| 摘要 |
PROBLEM TO BE SOLVED: To prevent the cracking and the breakout of a cast slab by executing the change of an operational condition when a depression depth is larger than a reference value or satisfies a specific relational formula. SOLUTION: A profile of the thickness surface of the cast slab M is continuously detected with a laser beam range finder 4 arranged facing to the thickness surface of the cast slab M at a position befind a mold. The max. value in a prescribed casting length range in an average value deviation obtd. by subtracting the average value of oscillation recessed parts from the average value of projecting parts in each oscillation mark developing period is made to be the depression depth DPmax . At the time of satisfying at least one of the following conditions (1) and (2), the change of the operational condition is executed. (1) When the depression depth is larger than the reference value, (2) when the depression depth in the length range in a casting direction and an estimated shell thickness D derived from the operational condition satisfy the following formula, Uniformity = (D-α×DPmax )/D <= reference value. Wherein,αis an index for recess in the cast slab and is mainly decided from the kind of steel.
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