Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F3/00—Press section of machines for making continuous webs of paper
  • D21F3/02—Wet presses
  • D21F3/0209—Wet presses with extended press nip
  • D21F3/0218—Shoe presses

Definitions

• the present invention relates to a shoe press for paper/board machines, comprising a press shoe and a counter roll, which between themselves form an extended nip for a paper or cardboard web and for a circulated flexible belt, at least one hydraulic loading cylinder with a working chamber supplied with hydraulic fluid and adapted to press the press shoe against the counter roll, and a hydraulic fluid chamber supplied with hydraulic fluid and positioned between the side of the press shoe facing the loading cylinder and the opposing side of the loading cylinder.
• DE-195 15 832 discloses a shoe press in which the supplying of the pressure chamber with hydraulic fluid is carried out via a throttle extended from the working chamber and arranged in the piston of the loading cylinder.
• a drawback of this known arrangement is that the ratio of the pressure in the working chamber to the pressure in the hydraulic fluid chamber is already locked at the construction stage.
• the object of the invention is to eliminate this drawback.
• Fig. 1 is a cross-sectional view of the first embodiment of the shoe press
• Fig. 2 is a cross-sectional view of the second embodiment of the shoe press.
• press shoe is made in a single piece and extends in the cross direction, whereas loading cylinders, hydrostatic compartments and pressure chambers can be several in number, distributed in the longitudinal direction of the press shoe (cross direction) .
• the shoe press com- prises a press shoe 300 and a counter roll 312, which form a nip N between themselves.
• nip N run a paper web W which is to be dewatered, a circulated flexible press belt 311 and a press felt F.
• the press shoe is pressed against the counter roll 312 by means of a load- ing cylinder 310 with piston 330 and cylinder part 340.
• An O-ring seal therebetween is designated 380.
• the piston is attached to the horizontal beam 309 included in the frame system of the shoe press, by means of screws 350.
• the working chamber 325 of the loading cylinder 310 is supplied with hydraulic fluid by means of a horizontal duct 326 which is formed in the piston and which is shared by all the pistons, and a vertical duct 327 formed in the piston.
• a hydraulic fluid chamber 301 between the upper sur- face of the cylinder part 340 and the opposing side of the press shoe is delimited by an O-ring seal 336.
• the hydraulic fluid chamber 301 is supplied with hydraulic fluid through a duct 302 formed in the press shoe and having duct parts 302' and 302".
• the duct 302 receives the hydraulic fluid from a pipe 303 which extends in the longitudinal direction of the press shoe and is attached to one longitudinal side edge 304 (in this case, the ris- ing side) of the press shoe 300 by means of screws 305, which engage in threaded holes 305' in the press shoe.
• the duct or bore 306 of the pipe 303 communicates with the duct 302 by means of a throttle 308.
• the pipe 303 can be supplied with hydraulic fluid through its one end or both ends.
• the hydraulic fluid to the working chamber 305 and to the hydraulic fluid chamber 301 can have the same source, i.e. the ducts 306 and 326 can be branches of a common supply of hydraulic fluid (usually oil) and the fluid pressure in the working chamber 325 and the pressure chamber 311 can be controlled separately, for instance, by means of throttles and/or other known pressure control means, or different sources can be used for said hydraulic fluid supply.
• the hydraulic fluid chamber 301 has a slightly smaller area than the working chamber 325.
• the embodiment in Fig. 2 comprises the press shoe 400, the counter roll 312, the circulated press belt 311, the loading cylinder 410 with cylinder part 410A and piston 410B, a seal 480 arranged therebetween, and ducts 426 and 427 for supplying hydraulic fluid to the working chamber 425 of the loading cylinder.
• the hydraulic fluid chamber 301 is also in this case supplied with hydraulic fluid via ducts 402 with part 402" formed in the press shoe and receiving the hydraulic fluid from a pipe 403 attached to one longitudinal side edge of the press shoe, via a hole 408.
• the pipe is attached by means of screws 405 and screw holes 405'.
• the duct 402 opens into the hydraulic fluid chamber 301 by means of a throttle 402A.
• a feed pipe is designated 411.
• the shoe press in Fig. 2 also has a hydrostatic compartment 401 in its side facing the counter roll 312.
• This hydraulic fluid is supplied by means of a duct 402' branched off from the duct 402.
• the hole 408 in the pipe 403 in the form of a throttle delimits the hydraulic fluid flow to the compartment 401 to the desired level.
• the throttle 402A prevents the hydraulic fluid flow through the nip N from disappearing completely if the hydraulic fluid chamber 301 should leak.
• the hydraulic fluid chamber 301 has in this case a greater area than the working chamber 325.
• the pipes 303 and 403 are preferably made of aluminium, of which also the press shoe is usually made, and is manufactured by extrusion. By loosening the screw joints 305/305' and 405/405', the pipes 303 and 403 can be replaced with other pipes 303 and 403 having different dimensions, a different size of throttle etc.
• the inventive shoe press is applicable also to calendering operations in a paper or board machine.

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• Paper (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=20408467

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Family Cites Families (1)

• 1997
  • 1997-09-30 SE SE9703572A patent/SE510550C2/sv not_active IP Right Cessation
• 1998
  • 1998-09-30 WO PCT/SE1998/001761 patent/WO1999016970A1/en active IP Right Grant
  • 1998-09-30 EP EP98946772A patent/EP1027490B1/de not_active Expired - Lifetime
  • 1998-09-30 DE DE69811707T patent/DE69811707T2/de not_active Expired - Fee Related

Non-Patent Citations (1)

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