Method for making a roll shell of a roll used in the manufacture or further processing of paper and/or board

Abstract

The invention relates to a method for making a roll shell of a roll used in the manufacture or further processing of paper and/or board. In the method, a shell blank of the roll shell is made of steel and the shell blank is subjected to heat treatments comprising heating for hardening, quenching and tempering treatments. In accordance with the invention, in heat treatment, the quenching is carried out such that hardening takes place in a directed manner from the outer surface of the roll shell inwards. The quenching is carried out such that neutral or compression stress is produced in the surface of the roll and that the formation of tensile stress in the surface of the roll is prevented by means of quenching.

That which is claimed:  
     
         1 . A method for making a roll shell of a roll used in the manufacture or further processing of paper or board, the method comprising: 
 making a shell of steel, the shell comprising a tubular structure defined by a wall having a radially outer surface and a radially inner surface; and    heat-treating the shell to harden the shell, the heat-treating including heating, quenching, and tempering treatments, and wherein the quenching is carried out such that hardening of the shell takes place in a directed manner from the outer surface of the shell inward.    
     
     
         2 . The method of  claim 1 , wherein quenching is carried out by exposing the shell to a fluid medium.  
     
     
         3 . The method of  claim 2 , wherein the fluid medium is prevented from contacting the inner surface of the shell.  
     
     
         4 . The method of  claim 3 , wherein quenching is carried out by a fluidized bed method.  
     
     
         5 . The method of  claim 3 , wherein quenching is carried out such that neutral or compressive stress is produced in the outer surface of the shell.  
     
     
         6 . The method of  claim 3 , wherein formation of tensile stress in the outer surface of the shell is prevented by quenching.  
     
     
         7 . The method of  claim 3 , further comprising forming through-holes in the shell extending generally in an axial direction of the shell.  
     
     
         8 . The method of  claim 7 , wherein the through-holes are formed before heat treatment of the shell.  
     
     
         9 . The method of  claim 7 , wherein the through-holes are formed after heat treatment of the shell.  
     
     
         10 . A method for making a roll shell of a roll used in the manufacture or further processing of paper or board, the method comprising: 
 making a shell of steel, the shell comprising a tubular structure defined by a wall having a radially outer surface and a radially inner surface; and    heat-treating the shell to harden the shell, the heat-treating including steps of: 
 heating the shell to a temperature sufficient to cause transformation of the steel to an austenitic form;  
 quenching the shell by exposing the outer surface of the shell to a cooling medium while preventing the cooling medium from contacting the inner surface of the shell such that transformation of the steel to a martensitic form occurs at the outer surface of the shell and proceeds inwardly; and  
 tempering the shell.  
   
     
     
         11 . The method of  claim 10 , wherein the quenching is carried out such that the steel at the inner surface of the shell is unhardened.  
     
     
         12 . The method of  claim 10 , wherein the heat-treating is carried out such that neutral or compressive stress is created in the outer surface of the shell.