Smoothing device

Abstract

A smoothing device of a press arrangement for dewatering a fibrous web in a machine for producing or finishing the fibrous web including a rough belt, a smooth belt and a smoothing element. The rough belt being endless and water-absorbing. The rough belt arranged on a side of the fibrous web. The smooth belt is endless and arranged on an opposite side of the fibrous web. The rough belt, the fibrous web and the smooth belt running through a press nip together and the rough belt is led away from the fibrous web after passing through the press nip. The smoothing element forms a smoothing nip with the smooth belt after the rough belt is led away from the fibrous web, the smoothing element having a smooth pressing surface.

1 . A smoothing device of a press arrangement for dewatering a fibrous web in a machine for one of producing and finishing the fibrous web, comprising: 
 a rough belt being endless and water-absorbing, said rough belt arranged on a side of the fibrous web;    a smooth belt being endless and arranged on an opposite side of the fibrous web, said rough belt, the fibrous web and said smooth belt running through a press nip together, said rough belt being led away from the fibrous web after passing through said press nip; and    a smoothing element forming a smoothing nip with said smooth belt after said rough belt is led away from the fibrous web, said smoothing element having a smooth pressing surface.    
     
     
         2 . The smoothing device of  claim 1 , wherein said smooth belt transfers the fibrous web to said smoothing element.  
     
     
         3 . The smoothing device of  claim 1 , wherein at least one of said smoothing element and said smooth belt are arranged so that they move from each other.  
     
     
         4 . The smoothing device of  claim 1 , wherein said smooth belt has a first softness and said smoothing element has a second softness, said first softness greater than said second softness.  
     
     
         5 . The smoothing device of  claim 1 , wherein said smooth belt and said smoothing element are pressed with a contact force of between approximately 3 kN/m and 100 kN/m.  
     
     
         6 . The smoothing device of  claim 5 , wherein said contact force is between approximately 5 kN/m and 20 kN/m.  
     
     
         7 . The smoothing device of  claim 1 , wherein said smooth belt and said smoothing element are pressed with a contact force which is one of set and controlled as a function of a level of two-sidedness of the fibrous web after the smoothing device.  
     
     
         8 . The smoothing device of  claim 1 , wherein said smooth belt and said smoothing element are pressed with a contact force which is one of set and controlled as a function of a level of two-sidedness of the fibrous web after the machine.  
     
     
         9 . The smoothing device of  claim 1 , wherein said smoothing element is a smoothing belt that is endless and circulating.  
     
     
         10 . The smoothing device of  claim 1 , wherein said smoothing element is a smooth, rotatable smoothing roll.  
     
     
         11 . The smoothing device of  claim 10 , wherein said smoothing roll is heated.  
     
     
         12 . The smoothing device of  claim 1 , wherein said press nip is the last press nip of a plurality of press nips of the machine.  
     
     
         13 . The smoothing device of  claim 1 , further comprising a drying group for drying the fibrous web, the fibrous web being transferred from said smoothing element to said drying group in a transfer region.  
     
     
         14 . The smoothing device of  claim 13 , further comprising at least one suction device, the fibrous web being transferred in said transfer region with the assistance of said at least one suction device.  
     
     
         15 . The smoothing device of  claim 13 , wherein said drying group further includes: 
 a drying fabric supporting the fibrous web;    a plurality of drying cylinders;    a plurality of guide rolls, said drying fabric supporting the fibrous web being alternately guided over one of said plurality of drying cylinders and one of said plurality of guide rolls.    
     
     
         16 . The smoothing device of  claim 15 , wherein said plurality of drying cylinders are arranged under the fibrous web.  
     
     
         17 . The smoothing device of  claim 1 , wherein said smooth belt runs above the fibrous web.  
     
     
         18 . The smoothing device of  claim 15 , further comprising a suction device, the fibrous web being transferred to said drying fabric from said smoothing element in said transfer region, said suction device being proximate to said drying fabric in said transfer region.  
     
     
         19 . The smoothing device of  claim 18 , wherein said suction device is a suction box.  
     
     
         20 . The smoothing device of  claim 15 , wherein said smooth belt runs under the fibrous web.  
     
     
         21 . The smoothing device of  claim 20 , further comprising a transfer suction roll, the fibrous web being transferred from said smoothing element to said transfer suction roll, the fibrous web then being transferred from said transfer suction roll to said drying fabric.  
     
     
         22 . The smoothing device of  claim 20 , further comprising: 
 a suction device; and    an air permeable transfer belt wrapping around said suction device, the fibrous web being transferred from said smoothing element to said air permeable transfer belt, said air permeable transfer belt then transferring the fibrous web to said drying fabric.    
     
     
         23 . The smoothing device of  claim 22 , wherein said suction device is a suction roll.  
     
     
         24 . The smoothing device of  claim 1 , further comprising a suction device for attracting the fibrous web by suction, said suction device being arranged downstream of said smoothing element in a running direction of the fibrous web.  
     
     
         25 . The smoothing device of  claim 24 , wherein said suction device includes at least one of a suction box and a suction roll.  
     
     
         26 . The smoothing device of  claim 25 , wherein said suction box is arranged directly on an unwrapped region of a circumferential surface of said suction roll.  
     
     
         27 . The smoothing device of  claim 25 , wherein said suction box includes a first element and a second element each of which are pressed resiliently against the fibrous web with a contact force, a zone between said first element and said second element being a suction zone for attracting the fibrous web by suction.  
     
     
         28 . The smoothing device of  claim 27 , wherein said contact force of at least one of said first element and said second element is set to a predetermined value.  
     
     
         29 . The smoothing device of  claim 24 , further comprising a transfer belt, the fibrous web being transferred from said smoothing element to said transfer belt.  
     
     
         30 . The smoothing device of  claim 24 , further comprising a drying fabric, the fibrous web being transferred from said smoothing element to said drying fabric.  
     
     
         31 . The smoothing device of  claim 24 , further comprising: 
 at least one further suction device; and    a drying cylinder, the fibrous web after being transported past said suction device is conveyed over said drying cylinder and said at least one further suction device.    
     
     
         32 . The smoothing device of  claim 25 , wherein the fibrous web includes a threading strip associated with the fibrous web, at least one of said suction roll and said suction box including a region being separately evacuateable, said region corresponding to a width of said threading strip during the threading of the fibrous web.  
     
     
         33 . The smoothing device of  claim 25 , wherein at least one of said suction roll and said suction box is one of set on and off said smoothing element.  
     
     
         34 . A method of threading a strip of a fibrous web in a papermaking machine, comprising the step of applying a vacuum to the strip in a region proximate to one of a suction roll and a suction box.  
     
     
         35 . The method of  claim 34 , further comprising the step of completing a threading operation, said completing a threading operation including the steps of: 
 bringing the strip to a full width of the fibrous web by way of a couching device; and    contacting a drying fabric with a smoothing roll.