Patent ID: 7617710

Claim:
A tensionless leveller for levelling a metal strip and having an entry and an exit, comprising: n+1 motorized rolls each having a constant radius R; a lower superposed cassette supporting at least n/2 of the rolls; and an upper superposed cassette supporting at least n/2 of the rolls not supported by the lower superposed cassette; wherein the rolls are offset with respect to one another and are placed alternately above and below a path of the strip, an axis of each of the rolls of one of the lower or the upper cassette being separated from an axis of an immediately successive roll of the other of the lower or the upper cassette by a center-to-center spacing E k , in which: for k from 2 to 4, R/E k =R/E 1 ; for k from n−3 to n, R/E k =R/E n and R/E n <R/E 1 ; and for k from 5 to n−1, R/E n ≦R/E k ≦R/E 1 , and R/E k ≧R/E k+1 , a center-to-center spacing between a first roll of the rolls from the entry of the leveller and a second roll of the rolls from the entry of the leveller being E 1 , and a center-to-center spacing between a last roll of the rolls from the entry of the leveller and a next to last roll of the rolls from the entry of the leveller being E n .