METHOD AND APPARATUS FOR MANUFACTURING COLD-ROLLED STEEL STRIP

摘要

A cold-rolled strip manufacturing apparatus, in which a continuous cold reduction mill and a continuous annealing furnace are directly linked together, has a tension-leveller-type scale breaker for elongating hotrolled breakdown by not more than 7 percent, a scale scrubbing brush unit and an immersion-type continuous pickling tank installed upstream of the continuous cold reduction mill. Descaling of the hot-rolled breakdown is carries out by breaking the mill scale formed on its surface by causing the running breakdown to elongate and then removing the broken scale from the surface. Percent elongation is feedforward controlled on the basis of the manufacturing conditions of the hot-rolled breakdown and/or the properties and quantity of the mill scale formed. In another descaling method, percent elongation is feedback controlled on the basis of the condition of scale breaking and removing that is detected during the period in which the mill scale is broken and removed.