Dewatering bar on a papermaking machine and wire section of a papermaking machine

Abstract

A dewatering bar on a papermaking machine includes a main body with a longitudinal direction aligned transversely to the direction of movement of a screen belt. The main body has at least one chamber closed in a pressure tight manner, which extends in the longitudinal direction of the dewatering bar. The chamber has a connection to a pressure line, a wall having a surface facing the screen belt of the papermaking machine, and side walls connected to the wall. The position of the wall of the chamber is variable, and a device for detecting the change in position of the wall due to changes in the pressure is disposed in the chamber. A wire section of a papermaking machine is also provided.

1 . A dewatering bar for a papermaking machine, the dewatering bar comprising:
 a main body having a longitudinal direction aligned transversely to a direction of movement of a screen belt of the papermaking machine, said main body having at least one chamber being closed in a pressure tight manner;   said at least one chamber extending in a longitudinal direction of the dewatering bar, and said at least one chamber having a connection for a pressure line;   said at least one chamber having a wall and side walls connected to said wall, said wall having a surface facing the screen belt and said wall having a variable position; and   a device for detecting a change in position of said wall due to changes in pressure in said chamber.   
     
     
         2 . The dewatering bar according to  claim 1 , wherein said wall is deformable. 
     
     
         3 . The dewatering bar according to  claim 1 , wherein said device for detecting a change in the position of said wall is a sensor. 
     
     
         4 . The dewatering bar according to  claim 3 , wherein said sensor is a tilt sensor or a displacement sensor. 
     
     
         5 . The dewatering bar according to  claim 1 , wherein said device for detecting a changed in the position of said wall is disposed in said chamber. 
     
     
         6 . The dewatering bar according to  claim 2 , wherein said wall is made deformable by having regions with different bending stiffness values. 
     
     
         7 . The dewatering bar according to  claim 6 , wherein said wall includes a region having a lower bending stiffness than an adjoining region, and said region having a lower bending stiffness runs in the longitudinal direction of the dewatering bar or obliquely to the longitudinal direction of the dewatering bar. 
     
     
         8 . The dewatering bar according to  claim 1 , wherein said wall includes a region having a lower bending stiffness than adjoining regions of a respectively adjoining one of said side walls, and said region having a lower bending stiffness is disposed in a region of transition from at least one of said side walls to said wall. 
     
     
         9 . The dewatering bar according to  claim 1 , wherein at least one of said side walls has regions with different bending stiffness values. 
     
     
         10 . The dewatering bar according to  claim 5 , wherein said wall includes a region having a lower bending stiffness than at least one adjoining region of at least one of said wall or at least one of said side walls, and said region of lower bending stiffness has a groove formed therein. 
     
     
         11 . The dewatering bar according to  claim 10 , wherein said groove is inwardly open toward said chamber. 
     
     
         12 . The dewatering bar according to  claim 1 , wherein said chamber is one of at least two chambers being closed in a pressure tight manner, said at least two chambers extending in the longitudinal direction of the dewatering bar and being disposed side-by-side, and each of said at least two chambers has a separate connection to a pressure line. 
     
     
         13 . The dewatering bar according to  claim 12 , wherein each of said at least two chambers is associated with a portion of said variable-position wall having a portion of said surface facing the screen belt of the papermaking machine, and said device for detecting the change in position of said wall is one of at least two devices each being associated with a respective one of said at least two chambers. 
     
     
         14 . The dewatering bar according to  claim 1 , wherein said surface facing the screen belt has a first surface segment enclosing a first acute angle with the screen belt, and said first acute angle opens in the direction of movement of the screen belt. 
     
     
         15 . The dewatering bar according to  claim 14 , wherein:
 said surface facing the screen belt has a second surface segment disposed after said first surface segment in the direction of movement of the screen belt;   said second surface segment encloses a second acute angle with the screen belt and said second acute angle closes in the direction of movement of the screen belt; and   said surface facing the screen belt has at least one further surface segment running parallel to the screen belt.   
     
     
         16 . The dewatering bar according to  claim 15 , wherein said at least one further surface segment is disposed between said first surface segment and said second surface segment. 
     
     
         17 . The dewatering bar according to  claim 1 , wherein said wall is in contact with the screen belt and said wall is produced from a wear-resistant material, at least in some segment or segments. 
     
     
         18 . The dewatering bar according to  claim 1 , which further comprises at least one of a leading edge or a trailing edge as viewed in the direction of movement of the screen belt, and a strip of wear-resistant material disposed on at least one of said leading edge or said trailing edge. 
     
     
         19 . The dewatering bar according to  claim 18 , wherein said wear-resistant material is a ceramic. 
     
     
         20 . The dewatering bar according to  claim 18 , wherein said strip is secured releasably on said main body at least at one of said leading edge or said trailing edge. 
     
     
         21 . The dewatering bar according to  claim 18 , which further comprises a carrier body disposed releasably on said main body, said strip being secured on said carrier body at least at one of said leading edge or said trailing edge. 
     
     
         22 . The dewatering bar according to  claim 21 , wherein said carrier body is made of glass fiber-reinforced plastic. 
     
     
         23 . The dewatering bar according to  claim 1 , wherein said main body is made of plastic. 
     
     
         24 . The dewatering bar according to  claim 23 , wherein said plastic is polyethylene. 
     
     
         25 . The dewatering bar according to  claim 1 , wherein said main body is formed of at least a bottom part for securing said main body on a carrier bar and a top part having said wall of said chamber. 
     
     
         26 . A wire section of a papermaking machine, the wire section comprising:
 at least one dewatering bar according to  claim 1 ; and   a screen belt configured to move over the dewatering bar transversely to the longitudinal extent of the dewatering bar.