Method and apparatus for manufacturing cold-rolled steel strip

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 hot-rolled breakdown by 2 to 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 strip coil is carried out by breaking the mill scale formed on its surface by causing the running strip to elongate and then the broken scale is removed from the surface. The percent elongation given to the strip is feedforward controlled on the basis of the manufacturing conditions of the hot-rolled strip coil and/or the properties and quantity of the mill scale formed. In another descaling method, the percent elongation given to the strip 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.