Method of compensating for the roll deflection in a calender

Abstract

The method maintains a set nip clearance at a uniform value across the widths of the calendar, at different calendar loads, in at least the last nip, in the working direction, of a calender stack or the like including at least three rolls subjected to a common work-press load, with at least one roll being crowned to correspond to the maximum load of the calendar and at least one roll being adjustable. The thickness of the material being treated is sensed at one or several points in a direction transverse to the material web, or the deflection, or the load, is sensed at one or several of the rolls. The position of one or more adjustable rolls is displaced, relative to the common plane through the roll axes, in accordance with the sensing in a manner such that the axis of the adjustable roll or rolls remains parallel to the adjacent roll axis. The adjustable rolls may be displaced horizontally either linearly or arcuately to follow the contour of the adjacent rolls. The adjustment may be effected automatically responsive to measurements and to calculations performed by a computer.