4-high rolling mill

Abstract

A 4-high-rolling mill includes a pair of upper and lower works, a pair of upper and lower backup rolls supporting the upper and lower work rolls, respectively, a roll bending device for applying a bending force to the upper and lower work rolls, and a roll shift device for shifting the upper and lower work rolls in an axial direction of the work rolls. Each of the upper and lower work rolls has a curved initial crown portion formed on one side portion of a barrel of the work roll which is not less than a half of the length of the work roll barrel, and a substantially cylindrical initial crown portion formed on the remainder of the work roll barrel. Teh curve of the curved initial crown portion approximates to a curve represented by the formula Y=X.sup.n, (n.gtoreq.1.5), and the curved initial crown portions of the upper and lower work rollers are disposed oppositely relative to each other in the axial direction of the work rolls, and always disposed in overlapping relation to each other at least a part thereof.