Extended-nip press

Abstract

An extended-nip press is disclosed comprising a press roll ( 2 ) and a backing roll ( 1 ), wherein the press roll ( 2 ) comprises a rotating endless-loop blanket ( 3 ) of a flexible, liquid-impervious material, a rigid and advantageously stationary roll support beam ( 4 ) that extends axially through the interior of the endless blanket ( 3 ), at least one shoe element ( 8 ) resting on the roll support beam ( 4 ) and having a concave top face, and loading means ( 6 ) for loading the shoe element ( 8 ) by way of pressing the concave top face thereof against the flexible endless-loop blanket ( 3 ) so as to make the blanket ( 3 ) form a press nip zone (N) in cooperation with the backing roll ( 1 ), said loading means ( 6 ) comprising a linear array of loading units ( 6′ ) aligned along the axial direction of the press roll ( 2 ), each one of the loading units comprising a functionally cooperating piston-cylinder unit. The invention is implemented by way of providing the piston ( 13 ) of said at least one piston-cylinder unit with a first end ( 14 ) which is adapted to enter at least partially into the bore of the cylinder ( 12 ) and to tilt relative to the cylinder ( 12 ) and, further, by providing said piston ( 13 ) of said at least one piston-cylinder unit with a second end ( 18 ) which is adapted to enter the piston mount ( 19 ) and to tilt relative to the piston mount, and, still further, by adapting the cylinder ( 12 ) of said at least one piston-cylinder movable between glide rails ( 21 ) aligned in the axial direction of the press roll ( 2 ) and is connected so as to load the endless-loop blanket ( 3 ) when a pressurized medium is introduced into the cylinder displacement space ( 15 ) formed between the piston ( 13 ) and the cylinder ( 12 ).

What is claimed is:  
     
         1 . An extended-nip press formed by a press roll ( 2 ) and a backing roll ( 1 ), said press roll ( 2 ) comprising 
 a rotating endless-loop blanket ( 3 ) of a flexible, liquid-impervious material,    a rigid and advantageously stationary roll support beam ( 4 ) that extends axially through the interior of the endless blanket ( 3 ),    at least one shoe element ( 8 ) resting on the roll support beam ( 4 ) and having a concave top face, and    loading means ( 6 ) for loading the shoe element ( 8 ) by way of pressing the concave top face thereof against the flexible endless-loop blanket ( 3 ) so as to make the blanket ( 3 ) form a press nip zone (N) in cooperation with the backing roll ( 1 ), said loading means ( 6 ) comprising a linear array of loading units ( 6 ′) aligned along the axial direction of the press roll ( 2 ), each one of the loading units comprising a functionally cooperating piston-cylinder unit,    characterized in that    the piston ( 13 ) of said at least one piston-cylinder unit comprises a first end ( 14 ) which is adapted to enter at least partially into the bore of the cylinder ( 12 ) and to tilt relative to the cylinder ( 12 ),    said piston ( 13 ) of said at least one piston-cylinder unit further comprises a second end ( 18 ) which is adapted to enter the piston mount ( 19 ) and to tilt relative to the piston mount, and    the cylinder ( 12 ) of said at least one piston-cylinder unit is adapted movable between glide rails ( 21 ) aligned in the axial direction of the press roll ( 2 ) and is connected so as to load the endless-loop blanket ( 3 ) when a pressurized medium is introduced into the cylinder displacement space ( 15 ) formed between the piston ( 13 ) and the cylinder ( 12 ).    
     
     
         2 . The extended-nip press of  claim 1 , characterized in that said first end ( 14 ) of said piston is at least partially globular.  
     
     
         3 . The extended-nip press of  claim 1  or  2 , characterized in that said second end ( 18 ) of said piston is adapted to rest in the piston mount ( 19 ) on a spherical sliding bearing ( 20 ).  
     
     
         4 . The extended-nip press of any one of foregoing claims, characterized in that said glide rails ( 21 ) extend in a substantially contiguous fashion on both sides of the linear array of the piston-cylinder units.  
     
     
         5 . The extended-nip press of any one of foregoing claims, characterized in that key elements ( 23 ) are adapted between said at least one piston-cylinder unit and at least one of the glide rails ( 21 ) in order to prevent said at least one piston-cylinder unit from moving in the axial direction of the extended-nip press.  
     
     
         6 . The extended-nip press of  claim 5 , characterized in that key elements ( 23 ) are adapted between said at least one piston-cylinder unit of the five centermost piston-cylinder units, advantageously the selected piston-cylinder unit being the centermost of them all, and at least one of the glide rails ( 21 ) in order to prevent said at least one piston-cylinder unit from moving in the axial direction of the extended-nip press.  
     
     
         7 . The extended-nip press of any one of foregoing claims, characterized in that the shoe ( 8 ) is connected to at least one loading unit ( 6 ′) so that the frictional forces imposed on the shoe ( 8 ) are transmitted to said at least one loading unit ( 6 ′).  
     
     
         8 . The extended-nip press of any one of foregoing claims, characterized in that the end of the cylinder ( 12 ) loading the shoe is made at least partially spherical.  
     
     
         9 . The extended-nip press of any one of foregoing claims, characterized in that the cylinder ( 12 ) of said at least one piston-cylinder unit includes a force-receiving surface ( 22 ) adapted to rest against the glide rail ( 21 ) so as to transmit the frictional forces imposed on the shoe ( 8 ) of the extended-nip press to the roll support beam ( 4 ) of the extended-nip press.  
     
     
         10 . The extended-nip press of any one of foregoing claims, characterized in that in said linear array of loading units ( 6 ′), advantageously their cylinders ( 12 ) are adapted abut each other at least partially.