Shoe suction press roll

Abstract

This invention relates to a press device with a suction press roll. According to the invention, a linear force increase can be achieved in press devices with suction press rolls of identical or smaller size than conventional suction press rolls by equipping the suction press rolls with a compliance compensator. Said compliance compensator is arranged parallel to the longitudinal axis of the suction press roll in said suction press roll. Different concepts are possible depending on the roll cover construction and the arrangement of the suction box, whereby the one first embodiment is characterized by the integration of a shoe press roll in the suction press roll. A second embodiment is characterized by the combination of a routing of connection channels between the press nip and the suction box through the roll cover with an integrated compliance compensator in the interior space enclosed by the roll cover.

1 . A press device, comprising
 a suction press roll including a rotatable perforated roll cover, at least one suction zone, and a first shoe press roll, said rotatable perforated roll cover including an inner circumference, said at least one suction zone extending over a region of said inner circumference in a circumferential direction, said first shoe press roll arranged in an inside of said rotatable perforated roll cover and acting against said inner circumference.   
   
   
       2 . The press device according to  claim 1 , wherein said first shoe press roll includes a flexible circulating belt forming a flexible roll cover and a pressing-on unit assigned to said flexible circulating belt, said flexible circulating belt including an inner face, said pressing-on unit having at least one pressing-on element with a pressing-on face which is pressable against said inner face of said flexible circulating belt. 
   
   
       3 . The press device according to  claim 2 , wherein said first shoe press roll includes a supporting element and a device for generating a pressing-on force, said pressing-on element being a press shoe which is at least one of hydrostatically and hydrodynamically lubricated, is braced on said supporting element, has a convex pressing-on face, and can be actuated via said device for generating said pressing-on force. 
   
   
       4 . The press device according to  claim 3 , wherein said pressing-on force is generated at least one of hydraulically, pneumatically, and mechanically. 
   
   
       5 . The press device according to  claim 3 , wherein said pressing-on force of said pressing-on unit is controllable parallel to a longitudinal axis of said suction press roll. 
   
   
       6 . The press device according to  claim 5 , wherein said pressing-on force is controllable on a zone basis over a width of said suction press roll. 
   
   
       7 . The press device according to  claim 5 , wherein said pressing-on force is controllable one of steplessly and in a plurality of steps. 
   
   
       8 . The press device according to  claim 1 , wherein said suction press roll includes a stationary suction box, said suction zone being formed by said stationary suction box which can be loaded with a vacuum. 
   
   
       9 . The press device according to  claim 8 , wherein said suction box is sealed against said inner circumference by a plurality of sealing devices. 
   
   
       10 . The press device according to  claim 1 , wherein the press device forms a press nip, said suction zone including a) a pre-suction compartment between said inner circumference and said flexible circulating belt and b) a holding zone downstream from said press nip between said first shoe press roll and said inner circumference. 
   
   
       11 . The press device according to  claim 1 , wherein said rotatable perforated roll cover includes an outer circumference and said rotatable perforated roll cover includes a plurality of perforations formed by a plurality of through-openings extending through said rotatable perforated roll cover from said outer circumference to said inner circumference in a radial direction. 
   
   
       12 . The press device according to  claim 1 , further including a device for generating a vacuum in the suction zone, said device for generating a vacuum in the suction zone being assigned to said suction press roll at an end face of said suction press roll. 
   
   
       13 . The press device according to  claim 1 , further including a mating roll for said suction press roll, said mating roll being a second shoe press roll. 
   
   
       14 . The press device according to  claim 1 , further including a mating roll for said suction press roll, said mating roll being a solid cover press roll. 
   
   
       15 . A press device, comprising:
 a mating roll; and   a suction press roll including a roll cover, at least one suction device, a first pressing-on unit, and a stationary supporting element, said roll cover being rotatable and rigid, enclosing an interior space, and having at least one channel routed in said roll cover for coupling with said at least one suction device arranged outside said interior space and acting via said at least one channel on a surface of said roll cover, said roll cover including an inner circumference, said suction press roll and said mating roll forming a press nip, the press device including a region of said press nip, and said first pressing-on unit being arranged in said interior space, being braced on said stationary supporting element, and being active at said inner circumference of said roll cover in said region of said press nip with said mating roll.   
   
   
       16 . The press device according to  claim 15 , wherein said suction press roll includes a second pressing-on unit which is arranged offset to said first pressing-on unit in a circumferential direction and which includes at least one pressing-on element which becomes active at said inner circumference. 
   
   
       17 . The press device according to  claim 16 , wherein said suction press roll includes another stationary supporting element and at least one device for generating a pressing-on force, said first pressing-on unit including at least one pressing-on element, each of said pressing-on elements of said first and second pressing-on units being a piston element which is at least one of hydrostatically and hydrodynamically lubricated, is braced on one of said supporting elements, and can be actuated via said at least one device for generating said pressing-on force. 
   
   
       18 . The press device according to  claim 17 , wherein said pressing-on force is generated at least one of hydraulically, pneumatically, and mechanically. 
   
   
       19 . The press device according to  claim 17 , wherein each of said first and second pressing-on units includes a plurality of said pressing-on elements, said pluralities of pressing-on elements being arranged over a width of said suction press roll parallel to a longitudinal axis of said suction press roll, each of said pressing-on elements configured for being actuated one of singly and in a group of said pressing-on elements. 
   
   
       20 . The press device according to  claim 15 , wherein said roll cover includes an outer circumference and a plurality of openings worked into said outer circumference of said roll cover and wherein said at least one channel is at least one central suction channel which is arranged in said roll cover and which extends parallel to a longitudinal axis of said suction press roll through said roll cover and into which said plurality of openings worked into said outer circumference of said roll cover open. 
   
   
       21 . The press device according to  claim 15 , wherein each said channel is arranged in said roll cover and has two openings which are arranged offset relative to each other in a circumferential direction and lead out of said suction press roll, said at least one suction device being outside said press nip and acting on an outer cover face of said roll cover, a distance between respective said two openings of each said channel in said circumferential direction being such that during rotation of said roll cover said at least one suction device always stands in connection to at least a part of said openings momentarily in said press nip via a respective said channel. 
   
   
       22 . A method for converting a press device with a suction press roll, said method comprising the steps of:
 replacing the suction press roll with another suction press roll to increase the establishable linear press in a press nip, said other suction press roll including a rotatable perforated roll cover, at least one suction zone, and a first shoe press roll, said rotatable perforated roll cover including an inner circumference, said at least one suction zone extending over a region of said inner circumference in a circumferential direction, said first shoe press roll arranged in an inside of said rotatable perforated roll cover and acting against said inner circumference.   
   
   
       23 . A press apparatus, comprising:
 a first press device including a first roll, a second roll, a central roll, and a third roll, said first roll and said second roll together forming a first press nip, said second roll being a mating roll, said first roll and said central roll together forming a second press nip arranged downstream from said first press nip in a fibrous web running direction, said central roll and said third roll forming a third press nip therebetween, one of said first roll, said second roll, said central roll, and said third roll of said first press device being a first suction press roll; and   a second press device arranged downstream from said first press device and including two rolls forming another press nip, one of said two rolls of said second press device being a second suction press roll.   
   
   
       24 . The press apparatus according to  claim 23 , wherein said first roll of said first press device is said first suction press roll. 
   
   
       25 . The press apparatus according to  claim 23 , wherein said first and second suction press rolls are identical. 
   
   
       26 . The press apparatus according to  claim 25 , wherein each of said first and second suction press rolls includes a rotatable perforated roll cover, at least one suction zone, and a first shoe press roll, said rotatable perforated roll cover including an inner circumference, said at least one suction zone extending over a region of said inner circumference in a circumferential direction, said first shoe press roll arranged in an inside of said rotatable perforated roll cover and acting against said inner circumference.