Head box for paper making machine with improved nozzle for stock solution

Abstract

This invention relates to an improved structure of a head box for a paper making machine. The sidewalls of a nozzle of a head box shall be movable with the rotation of a roll transporting a forming wire of the paper making machine. Thus, the homogeneity of produced paper can be improved and the production rate of paper increased.

What is claimed is:  
     
         1 . A head box for a paper making machine, comprising: 
 (a) a stock solution inlet line for feeding stock solution,    (b) a nozzle for being fed with said stock solution by said inlet line, and for spraying said stock solution on a forming wire of said paper making machine during a rotating movement of said forming wire on a roll relative to said nozzle,    (c) wherein said nozzle has an output opening to be positioned directly adjacent said forming wire,    (d) sidewalls being provided mutually opposed for essentially inhibiting stock solution flowing out in said axial direction,    (e) wherein said sidewalls are rotatable with said roll in said rotating movement relative to said nozzle characterized in that said sidewalls defining a width of said output opening in an axial direction of said roll for inhibiting stock solution flowing out of said output opening in said axial direction.    
     
     
         2 . A head box according to  claim 1 , wherein said sidewalls are annular and adapted to be concentric with said roll.  
     
     
         3 . A head box according to  claim 2 , wherein said nozzle has lips, at least one of which comprises side parts being directly adjacent to said annular sidewalls, a sealing being provided between said lip side parts and said sidewalls for essentially inhibiting stock solution flowing out and for allowing a rotating movement of said sidewalls with said roll relative to said lip side parts.  
     
     
         4 . A head box according to  claim 3 , wherein said sealing comprises a pressure water sealing.  
     
     
         5 . A head box according to  claim 4 , wherein said pressure water sealing is adapted to provide some water flow from said sealing to said stock solution for inhibiting a stock congestion at said sidewalls.  
     
     
         6 . A head box according to one of the preceding claims, wherein said sidewalls are adapted to be axially movable relative to said roll in order to compensate for some axial movement of said forming wire during said movement.  
     
     
         7 . A head box according to  claim 6 , wherein said nozzle is fixed to said sidewalls with regard to said axial movability.  
     
     
         8 . A head box according to  claim 6  or  7  with a movement drive for said axial movability and with a sensor for detecting a position of said forming wire in said axial direction, wherein said movement drive is controllable in response to said forming wire position sensor.  
     
     
         9 . A head box according to one of  claims 3  to  8 , wherein said sealing comprises sealing rings and elastic pressure fluid containers for pressing that sealing rings against sealing surfaces.  
     
     
         10 . A head box according to one of  claims 1  to  5 , wherein said sidewalls are adapted to be fixed to said roll and have tapered surfaces on inner sides thereof for allowing some axial movement and inhibiting an excessive axial movement of said forming wire on said roll.  
     
     
         11 . A head box according to  claim 10 , wherein said tapered surfaces are concave in a section along said axial direction.  
     
     
         12 . A head box according to one of the preceding claims adapted for a Fourdrinier or twin-wire or inclined-wire paper making machine.  
     
     
         13 . A head box according to one of the preceding claims, comprising said roll.  
     
     
         14 . A method of making paper using a head box according to one of the preceding claims and comprising the steps of: 
 (a) providing a stock solution inlet line for feeding stock solution,    (b) providing a nozzle for being fed with said stock solution by said inlet line,    (c) providing a forming wire for receiving said stock solution from said nozzle, for extracting water from said stock solution, and    (d) providing a roll for a rotating movement for transporting said forming wire,    (e) wherein side walls being provided mutually opposed, and    (f) wherein said nozzle has,    (g) an output opening directly adjacent said forming wire,    (h) said sidewalls essentially inhibiting stock solution flowing in said axial direction,    (i) wherein said sidewalls are rotated with said roll in said rotating movement during paper making, characterized in that said sidewalls define a width of said output opening in an axial direction of said roll for inhibiting stock solution flowing out of said output opening in said axial direction.    
     
     
         15 . A paper making machine comprising a head box according to one of  claims 1  to  13 .