Process and a device for the formation of fiberboard

Abstract

A process for the formation of fiberboard where the fiber stock suspension is dewatered on two sides between wires or felts, a top wire being provided in the main dewatering zone.

1 . Device for forming wood fiber board from a wood fiber stock suspension has a basic weight of 1200 to 8000 g/m 2 , the device comprising a first headbox; a main dewatering zone having a first top wire or felt and a bottom wire or felt, the first top wire and the bottom wire forming a first wedge zone having an inlet end and an outlet end; and apparatus for pressure loading the outlet end of the first wedge zone.  
   
   
       2 . Device according to  claim 1  wherein the first wedge zone is adjustable.  
   
   
       3 . Device according to  claim 1  wherein the bottom wire runs essentially horizontally.  
   
   
       4 . Device according to  claim 1  further comprising support means for supporting the wire or felt in the first wedge zone said support means comprising perforated plastic, steel plates, foil strips or table rolls.  
   
   
       5 . Device according to  claim 1  further comprising a second headbox for applying a top layer.  
   
   
       6 . Device according to  claim 5  further comprising a second dewatering zone having a second top wire or felt and the bottom wire or felt forming a second wedge zone.  
   
   
       7 . Device according to  claim 6  wherein the second wedge zone has an inlet end and an outlet end, the second wedge zone being pressure loaded at the outlet end.  
   
   
       8 . Device according to  claim 1  further comprising several press nips, each of the press nips including opposed press rolls.  
   
   
       9 . Device according to  claim 8  wherein the press rolls are arranged substantially vertically above one another.  
   
   
       10 . Device according to  claim 8  wherein the press rolls in the press nips are suitable for individual pressure loading.  
   
   
       11 . Device according to  claim 1  wherein the machine frame is suitable for cantilevering.  
   
   
       12 . Device according to  claim 1  further including two to six press nips.  
   
   
       13 . Device according to  claim 1  further including three to five press nips.  
   
   
       14 . Device according to  claim 1  further including a controller for controlling the apparatus for pressure loading.  
   
   
       15 . Device according to  claim 14  wherein the controller and apparatus for pressure loading maintain a substantially constant pressure load at the outlet end of the first wedge zone.  
   
   
       16 . Device according to  claim 14  wherein the apparatus for pressure loading is a pneumatic or hydraulic tube.