Patent ID: 6289797
Filing Date: 2001-09-18
Classification: D21F,D21G

Abstract:
A method for calendering a paper web, comprising the steps of:passing the paper web through a calendering nip formed by two calender rolls and having a nip profile defined by the rolls, at least one of the rolls being a soft-faced roll comprising a rotating tubular body part having an inner and an outer surface,arranging a surface layer of a resilient or polymeric material on the outer surface of the rotating tubular body part such that the resilient surface is in direct contact with the outer surface of the tubular body part, the surface layer thereby forming an interface with the rotating tubular body part, andcontrolling the profile of the calendering nip to compensate for defects in the paper web entering the calendering nip byarranging a profile control device along the inner surface of the tubular body part of the soft-faced roll, the profile control device having a plurality of axially extending zones arranged along an axis of the soft-faced roll and adjacent the body part, andby means of the profile control device, independently controlling the temperature of each of the zones of the rotating tubular body which in turn directly heats the resilient surface by conduction across the interface between the outer surface of the rotating tubular body part and the resilient surface to thereby enable a change in a diameter of the soft-faced roll, as a result in the temperature change of the tubular body part and the surface layer, at each of the zones independent of any change in the diameter of the soft-faced roll at other zones, wherein the step of controlling the temperature of each of the zones comprises the steps of:directing a heat transfer medium into each of the zones, wherein said heat transfer medium is a gaseous medium; andarranging a heating element in each of the zones.