Patent attributes
There are provided a work-side position measurement device and a drive-side position measurement device for directly measuring positions of roll chocks in a rolling direction, and positions of upper and lower working rolls and upper and lower backup rolls in the rolling direction are adjusted to zero point or predetermined positions. Alternatively, a change caused in the strip wedge due to a minute crossing of the axes of working rolls and backup rolls is calculated, and the quantities of leveling of a work-side rolling reduction cylinder device and a drive-side rolling reduction cylinder device are adjusted to make the strip edge equal to or smaller than a predetermined value. Accordingly, the bilateral asymmetry (strip wedge) of the thickness distribution of a rolled material is easily adjusted even in the event that the positions of the roll chocks in the rolling direction are changed due to wear on various components.