Method of rolling metal strip

Claim 1

In a method of rolling metal strip in a rolling mill stand having at least three work rolls positioned substantially in a line with each other with each pair of adjoining work rolls forming a roll pass therebetween, the pair of work rolls at one end of the line forming an entry pass at an entry end of the stand and the pair of work rolls at the other end of the line forming an exit pass at an exit end of the stand, and which method includes driving the work rolls in the successive positions toward the exit end of the stand at increasingly greater peripheral speeds with each pair of adjoining work rolls having a lower-speed work roll toward the entry end of the stand and a higher-speed work roll toward the exit end of the stand, and feeding the metal strip into the entry pass, around the peripheries of the work rolls positioned between the work rolls at the respective ends of the line and through the rolls at the respective ends of the line and through the roll pass formed between each pair of adjoining work rolls along the line, the improvement which comprises: controlling the speed of at least the higher-speed roll forming the entry pass for causing the ratio of the entry speed of the strip to the peripheral speed of the lower-speed work roll in the entry pass to be greater than 0.8 and less than 1; and driving the work rolls for causing the peripheral speed of the higher-speed work roll in one of the pairs of adjoining work rolls to be greater than the exit speed of the strip from said one of the pairs of adjoining work rolls, and, at the same time, controlling the speeds of the rolls forming all the passes other than the entry pass for causing the ratio of the exit speed of the strip to the peripheral speed of the higher-speed work roll in each such pass to lie between 0.8 and 1.2.