Refiner bars having stepped coatings

Abstract

Disclosed is a refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers. The refiner filling piece is mountable to the rotor or the stator. The refiner filling piece comprises a base and a plurality of spaced-apart refiner bars, each refiner bar being defined by a bar length and a bar height. At least some of the refiner bars have a surface coated with a stepped coating. The surface having the stepped coating may be the leading surface of the refiner bar.

1 . A refiner filling piece for a refiner having a rotor that rotates about an axis of rotation and cooperates with a stator to mechanically treat a pulp containing cellulosic fibers, the refiner filling piece being mountable to the rotor or the stator, the refiner filling piece comprising:
 a base;   a plurality of spaced-apart refiner bars, each refiner bar being defined by a bar length and a bar height; and   wherein at least some of the refiner bars have a surface coated with a stepped coating.   
     
     
         2 . The refiner filling piece of  claim 1  wherein the stepped coating has a first coating thickness over a first portion of the bar height and a second coating thickness over a second portion of the bar height. 
     
     
         3 . The refiner filling piece of  claim 2  comprising an uncoated portion extending from the base to the stepped coating. 
     
     
         4 . The refiner filling piece of  claim 3  wherein the stepped coating extends to a top end of the refiner bar. 
     
     
         5 . The refiner filling piece of  claim 1  wherein the surface that is coated with the stepped coating is a leading surface of the refiner bar. 
     
     
         6 . The refiner filling piece of  claim 1  wherein the second portion of the bar height having the second coating thickness is taller than the first portion of the bar height having the first coating thickness. 
     
     
         7 . The refiner filling piece of  claim 1  wherein the stepped coating has a first coating thickness along a first portion of the bar length and a second coating thickness along a second portion of the bar length. 
     
     
         8 . The refiner filling piece of  claim 7  comprising an uncoated portion extending from a radially inner end of the refiner bar to the stepped coating. 
     
     
         9 . The refiner filling piece of  claim 8  wherein the stepped coating extends to a radially outer end of the refiner bar. 
     
     
         10 . The refiner filling piece of  claim 7  wherein the surface that is coated with the stepped coating is a leading surface of the refiner bar. 
     
     
         11 . The refiner filling piece of  claim 7  wherein the first portion of the bar length having the first coating thickness is longer than the second portion of the bar length having the second coating thickness. 
     
     
         12 . A refiner comprising:
 a housing;   a stator supported within the housing;   a rotor that rotates about an axis of rotation and cooperating with the stator to mechanically treat a pulp containing cellulosic fibers;   a first refiner filling piece fastened to the rotor; and   a second refiner filling piece fastened to the stator,   wherein the refiner filling piece comprises:   a base;   a plurality of spaced-apart refiner bars, each refiner bar being defined by a bar length and a bar height; and   wherein at least some of the refiner bars have a surface coated with a stepped coating.   
     
     
         13 . The refiner of  claim 12  wherein the stepped coating has a first coating thickness over a first portion of the bar height and a second coating thickness over a second portion of the bar height. 
     
     
         14 . The refiner of  claim 13  wherein the refiner bar comprises an uncoated portion extending from the base to the stepped coating. 
     
     
         15 . The refiner of  claim 14  wherein the stepped coating extends to a top end of the refiner bar. 
     
     
         16 . The refiner of  claim 12  wherein the surface that is coated with the stepped coating is a leading surface of the refiner bar. 
     
     
         17 . The refiner of  claim 12  wherein the second portion of the bar height having the second coating thickness is taller than the first portion of the bar height having the first coating thickness. 
     
     
         18 . The refiner of  claim 12  wherein the stepped coating has a first coating thickness along a first portion of the bar length and a second coating thickness along a second portion of the bar length. 
     
     
         19 . The refiner of  claim 18  wherein the refiner bar comprises an uncoated portion extending from a radially inner end of the refiner bar to the stepped coating. 
     
     
         20 . The refiner of  claim 19  wherein the stepped coating extends to a radially outer end of the refiner bar. 
     
     
         21 . The refiner of  claim 18  wherein the surface that is coated with the stepped coating is a leading surface of the refiner bar. 
     
     
         22 . The refiner of  claim 18  wherein the first portion of the bar length having the first coating thickness is longer than the second portion of the bar length having the second coating thickness.