Papermaking apparatus

Abstract

The present invention relates to an assembly of forming elements which together define in a papermaking apparatus a discontinuous supporting surface for a papermaking suspension to permit drainage and micro-turbulence to be accurately controlled, and to the papermaking apparatus per se.

1 . A papermaking apparatus capable of making a sheet of paper (or board) from a papermaking suspension, said apparatus comprising:  
     one or more supply means for introducing the papermaking suspension into a wet end of the apparatus;  
     a carrier for carrying the papermaking suspension from the wet end to an output end of the apparatus; and  
     an assembly of forming elements which include: 
 a primary blade positioned adjacent the one or more supply means;  
 a first secondary support blade coupled to a leading face of the primary blade by a first drainage deckle; and  
 optionally n consecutive additional secondary support blades and n consecutive additional drainage deckles, wherein a trailing face of the first additional secondary support blade is coupled to a leading face of the first secondary support blade by the first additional drainage deckle and a trailing face of the second to n th  additional secondary support blades is coupled respectively to a leading face of the first to n-1 th  additional secondary support blades by the second to n th  additional drainage deckle respectively,  
 wherein n is an integer of one or more,  
 whereby the upper surface of the primary blade, the first secondary support blade, the first drainage deckle, the n additional drainage deckles and the n additional secondary support blades together define a discontinuous surface for supporting the papermaking suspension.  
 
   
   
       2 . A papermaking apparatus as claimed in  claim 1  wherein the discontinuous supporting surface is irregularly discontinuous.  
   
   
       3 . A papermaking apparatus as claimed in  claim 1  wherein the discontinuous supporting surface is stepped.  
   
   
       4 . A papermaking apparatus as claimed in  claim 1  wherein the upper surfaces of the primary blade, the first secondary support blade and the n consecutive additional secondary support blades are substantially coplanar at a first height and the upper surface of at least one of the first drainage deckle and n consecutive additional drainage deckles is at a height different from the first height.  
   
   
       5 . A papermaking apparatus as claimed in  claim 4  wherein the upper surfaces of the primary blade, the first secondary support blade and the n consecutive additional secondary support blades are substantially coplanar at a first height and the upper surface of each of the first drainage deckle and n consecutive additional drainage deckles is at a height different from the first height whereby to define a discontinuous surface which is stepped.  
   
   
       6 . A papermaking apparatus as claimed in  claim 5  wherein the upper surfaces of the first drainage deckle and n consecutive additional drainage deckles are substantially coplanar at heights different from each other and from the first height whereby to define a discontinuous surface which is substantially irregularly stepped.  
   
   
       7 . A papermaking apparatus as claimed in  claim 5  wherein the upper surfaces of the first drainage deckle and n consecutive additional drainage deckles are substantially coplanar at a common height different from the first height whereby to define a discontinuous surface which is substantially regularly stepped.  
   
   
       8 . A papermaking apparatus as claimed in  claim 1  wherein the upper surfaces of at least one of the first drainage deckle and n consecutive additional drainage deckles is angled.  
   
   
       9 . A papermaking apparatus as claimed in  claim 8  wherein the upper surface is angled downwardly from trailing to leading edges of the upper surface.  
   
   
       10 . A papermaking apparatus as claimed in  claim 1  wherein at least one of the first drainage deckle and n consecutive additional drainage deckles generates micro-turbulence in the papermaking suspension by extrinsic means.  
   
   
       11 . A papermaking apparatus as claimed in  claim 1  wherein at least one of the first drainage deckle and n additional drainage deckles is adapted to transmit a means for generating micro-turbulence in the papermaking suspension.  
   
   
       12 . A papermaking apparatus as claimed in  claim 1  wherein the upper surface of at least one of the first drainage deckle and n consecutive additional drainage deckles comprises a groove adapted to transmit fluid onto its upper surface.  
   
   
       13 . A papermaking apparatus as claimed in  claim 12  wherein the groove is adapted to transmit pulses of fluid onto its upper surface.  
   
   
       14 . A papermaking apparatus as claimed in  claim 12  wherein to an end wall of at least one of the first drainage deckle and n consecutive additional drainage deckles extends a transverse slot outwardly from a transverse end wall of the groove.  
   
   
       15 . A papermaking apparatus as claimed in  claim 12  wherein to a first and second end wall of at least one of the first drainage deckle and n consecutive additional drainage deckles extends respectively a first and a second transverse slot outwardly from a first and second transverse end wall of the groove respectively.  
   
   
       16 . A method for constructing a papermaking apparatus as defined in any preceding claim comprising:  
     (a) obtaining a conventional papermaking apparatus comprising one or more conventional forming elements in the forming area;  
     (b) substituting at least one of the one or more conventional forming elements with an assembly of forming elements which include: 
 a primary blade positioned adjacent the one or more supply means;  
 a first secondary support blade coupled to a leading face of the primary blade by a first drainage deckle; and optionally n consecutive additional secondary support blades and n consecutive additional drainage deckles, wherein a trailing face of the first additional secondary support blade is coupled to a leading face of the first secondary support blade by the first additional drainage deckle and a trailing face of the second to n th  additional secondary support blades is coupled respectively to a leading face of the first to n-1 th  additional secondary support blades by the second to n th  additional drainage deckle respectively, wherein n is an integer of one or more, whereby the upper surface of the primary blade, the first secondary support blade, the first drainage deckle, the n additional drainage deckles and the n additional secondary support blades together define a discontinuous surface for supporting the papermaking suspension.  
 
   
   
       17 . An assembly of forming elements including: 
 a primary blade capable of being positioned adjacent one or more supply means at the wet end of a papermaking apparatus;    a first secondary support blade coupled to a leading face of the primary blade by a first drainage deckle; and    optionally n consecutive additional secondary support blades and n consecutive additional drainage deckles, wherein a trailing face of the first additional secondary support blade is coupled to a leading face of the first secondary support blade by the first additional drainage deckle and a trailing face of the second to n th  additional secondary support blades is coupled respectively to a leading face of the first to n-1 th  additional secondary support blades by the second to n th  additional drainage deckle respectively, wherein n is an integer of one or more, whereby the upper surface of the primary blade, the first secondary support blade, the first drainage deckle, the n additional drainage deckles and the n additional secondary support blades together define a discontinuous surface for supporting a papermaking suspension being carried by a carrier from the wet end to an output end of the papermaking apparatus.