Patent ID: 6039840
Filing Date: 2000-03-21
Classification: D21G

Abstract:
In a multi-nip calender including at least first, second and third calender rolls stacked in a substantially vertical column, said first calender roll being arranged between said second calender roll and said third calender roll such that said first calender roll defines a first calendering nip with said second calender roll and a second calendering nip with said third calender roll and is operatively loaded by said second and third calender rolls, the improvement comprising:said first calender roll comprising an elongate, tubular frame having a hollow interior and extending in an axial direction of said first calender roll, said frame having a middle area and lateral areas having an axial length extending between an end of said middle area and a respective end of said frame, said frame having a non-uniform rigidity such that said frame deforms in a radial direction less in said lateral areas than in said middle area during loading of said first calender roll,a polymer coating arranged on said frame of said first calender roll for compensating for the lesser deformation of said lateral areas of said frame during loading of said first calender roll, said polymer coating having a first portion arranged on said middle area of said frame and a second portion arranged on each of said lateral areas of said frame,said polymer coating including a layer of polymer material, said layer of polymer material and said frame being arranged such that the thickness of said layer of polymer material increases in said lateral areas over the axial length from the end of said middle area to the respective end of said frame and such that an outer diameter of the roll is substantially constant over the entire length of the roll in the axial direction.