Control method for multi-strand rolling mill

Abstract

When two strand workpieces pass through a roll opening between two grooved working rolls on a roll stand so as to be rolled, the trailing end of one of them may leave the rolls and cause change in the roll separation. At that time mating bilateral screw-down devices are remotely controlled to adjust the roll opening at least at the position of the remaining workpiece. Alternatively in a multi-strand tandem rolling mill, the rolling speeds on roll stands upstream of a roll stand which one of the strand workpieces has left are changed by a speed ratio of (1-b.sub.2)/(1-b.sub.1) where b.sub.1 and b.sub.2 respectively designate rates of backward slip when two strand workpieces are being rolled and in the absence of one of the strand workpieces from the last-mentioned roll stand. Alternatively the roll speeds on roll stands downstream of the roll stand which one of the strand workpieces has left may be changed by a speed ratio of (1+f.sub.2)/(1+f.sub.1) where f.sub.1 and f.sub.2 respectively designate rates of forward slip corresponding to the rates of backward slip b.sub.1 and b.sub.2.

Dependencies are inferred from the claim text.