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WO2000060165A1 - Appareil de liberation de bandes de papier pour rouleau preneur - Google Patents

Appareil de liberation de bandes de papier pour rouleau preneur Download PDF

Info

Publication number
WO2000060165A1
WO2000060165A1 PCT/CA2000/000271 CA0000271W WO0060165A1 WO 2000060165 A1 WO2000060165 A1 WO 2000060165A1 CA 0000271 W CA0000271 W CA 0000271W WO 0060165 A1 WO0060165 A1 WO 0060165A1
Authority
WO
WIPO (PCT)
Prior art keywords
pickup
paper web
roll
vacuum
air pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CA2000/000271
Other languages
English (en)
Inventor
Dean Warren Mcdonald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bowater Pulp and Paper Canada Inc
Original Assignee
Bowater Pulp and Paper Canada Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bowater Pulp and Paper Canada Inc filed Critical Bowater Pulp and Paper Canada Inc
Priority to AU32664/00A priority Critical patent/AU3266400A/en
Publication of WO2000060165A1 publication Critical patent/WO2000060165A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F2/00—Transferring continuous webs from wet ends to press sections
    • 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
    • D21F3/10—Suction rolls, e.g. couch rolls

Definitions

  • the invention relates to the field of paper production and in particular to an apparatus and method for selectively releasing a paper web from the pickup felt located in the press section of the paper production line.
  • the basic sections of a paper production line are the forming section, the press section and the drying section. Between the forming and press sections and between the press and drying sections, a transfer of the paper web produced by the production process is required.
  • U.S. Patent 3,981,084 issued September 26 1976 is directed to an apparatus used in a closed draw system wherein air pressure is applied to the moving paper web to facilitate transfer of the paper web from the forming wire to a pickup felt in the press section or from the pickup felt to the surface of a dryer roll in the drying section.
  • This is accomplished by the use of blow rolls positioned at the end of the forming and press sections respectively.
  • the construction of these blow rolls is substantially the same as a suction roll, except that a pressure chamber is located therein.
  • the gas pressure in the pressure chambers is preferably air at a pressure of up to 50.0 psi.
  • the blow roll includes a single positive pressure chamber which works in combination with the suction from the pickup roll, to urge the paper web away from the mesh of the forming wire to the pickup felt extending around the pickup roll.
  • a roll with independent suctioning and blowing apparatus which are used in combination to facilitate transfer of the paper web to the hot, smooth surface of a dryer in the drying section.
  • the blow roll contains two chambers, a pressure chamber and a vacuum chamber.
  • the pressure chamber communicates with an air header which in turn communicates with a suitable source of air pressure.
  • a vacuum source is connected to the vacuum chamber to provide the desired suction. Both the vacuum and pressure chambers are secured to a fixed support frame.
  • the pressure chamber and the suction chamber are not common, but are located adjacent one another with separate lines to their respective pressure and vacuum sources.
  • U.S. Patent 1,581,656 issued April 20, 1926 discloses an apparatus used in an open draw system for freeing the paper web from the wire mesh of the forming section, to allow the pickup felt contained in the press section to draw the paper web onto the pickup roll.
  • the apparatus advantageously uses the perforated couch roll of the forming section.
  • Independent suction and blowing means are used with respective suction and blowing chambers positioned in the couch roll adjacent one another.
  • the suction means removes excess moisture from the web as it nears the transfer point, while the blowing means produces a current of air under suitable pressure through the perforated couch roll to facilitate web transfer.
  • the suction chamber communicates through a pipe to a suitable suction apparatus.
  • the member containing the suction chamber has a partition at one end to form a pressure chamber to which air under pressure may be admitted. From the pressure chamber lead a plurality of passages which are formed in the casting. Air is moved through these passages along the length of the couch roll at a suitable pressure to free the paper web from the wire and forms a layer or cushion of air under the web to assist it in moving over to the press section.
  • this device uses separate chambers for the suctioning and the pressurized blowing function. — -> —
  • U.S. Patent 1,163.252 issued December 7, 1915 provides yet another means of providing pressurized air across the length of a suction roll.
  • a suction roll of the forming section is positioned adjacent a suction roll of the press section.
  • As the paper web moves along the forming section it encounters a suction box contained in the suction roll of the forming section.
  • As the paper web passes the suction box and moves toward the transfer point to the press section it encounters a slotted or perforated pipe which extends longitudinally along the inside of the suction roll. This perforated pipe is used for jetting air or steam from the suction roll to lift the paper web from the roll.
  • a similar set up is encountered at the end of the press section where a suction roll contains both a suction box and a perforated pipe.
  • the perforated pipe provides pressurized air to assist the paper web transfer from the press section to the drying section.
  • the perforated pipe is physically separate from the suction box and does not take advantage of any common valving.
  • the pickup roll is a suction roll. The suction assists in moving the web from the forming wire to the pickup felt.
  • the suction is turned off and the weight of the wet paper web is relied on to break the seal formed between the pickup felt and the web. Removal of the web is complicated by the fact that the pickup roll takes several seconds to lift vertically off the forming wire when dumping of the web occurs. For a variety of reasons the web may adhere in an undesirable manner to the pickup felt (e.g. the pickup felt is smooth or dirty). If the web is not released in a timely manner, it will tend to adhere to the pickup felt as the pickup roll moves vertically upward, resulting in paper web jams, macro-folding of the paper web, and ultimately damage to parts of the press section.
  • the present invention provides, in a pickup roll contained in the press section of a paper production line, the pickup roll comprising a perforated roll and a suction box disposed longitudinally in the perforated roll, vacuum means connected to the suction box, wherein a gas permeable pickup felt carrying a paper web is in contact with at least a sector of the pickup roll and in close cooperation with the suction box, and wherein the suction box directs air through the contacting portion of the pickup felt, the improvement comprising
  • switch means providing selective application of the vacuum or air pressure means to the suction box.
  • the paper production line is a closed draw system.
  • the suction means includes a vacuum pump.
  • the air pressure means includes a fan. More conveniently,
  • Switch means comprises a manually actuable switch or a programmable control feedback system.
  • the present invention provides, in the press section of a paper production line, a method of attracting and releasing a paper web from a pickup felt, the pickup felt in contact with at least a sector of a perforated pickup roll and in close cooperation with a suction box disposed longitudinally inside the perforated pickup roll, vacuum and air pressure means connected to the suction box. and switch means to selectively apply the vacuum or air pressure means, the method comprising the steps of
  • the vacuum means includes a vacuum pump. More preferably, the air pressure means includes a fan.
  • the switch means comprises a manually actuable switch or a programmable control feedback system.
  • the invention provides, in a paper production line, a paper web control apparatus comprising:
  • the paper production line is a closed draw system.
  • the air pressure means includes a fan.
  • the vacuum means includes a vacuum pump.
  • the means for selectively applying the vacuum source and the air pressure source to the common plenum comprises a manually actuable switch or a programmable control feedback system.
  • Figure 1 is a cross-sectional view of the forming section of a conventional paper production line
  • Figure 2 is a cross-sectional view of the press section of a conventional paper production line
  • Figure 3 is a cross-sectional view of a conventional pickup roll integral to the press section
  • FIG. 4 is a schematic drawing of the suction and blowing apparatus in accordance with the present invention.
  • Figure 5 is a cross-sectional view of the pickup roll in accordance with the present invention, highlighting the movement of the paper web.
  • FIG. 1 the forming section of a conventional paper production line is depicted.
  • the stock which is to be made into paper which is in the form of pulp mixed with a quantity of water, is fed to headbox 2 and then delivered onto wire mesh 4 through slice 6.
  • Wire mesh 4 is supported first by breast roll 8, from which point the wire and stock are carried by forming boards 10, and then by vacuum foils 12. the prime removers of water from the stock, so that the fibres may be left interwoven on wire mesh 4 in the form of a wet paper web (shown as 5 in Figure 3).
  • Wire mesh 4 passes over suction boxes 14 and couch roll 16.
  • the last major roll in the forming section is wire drive roll 18 which serves to drive wire mesh 4. and thus the rest of the rolls.
  • Couch pit 20 is designed to collect excess water from the wet paper web 5, as well as paper web 5 itself if the press section (shown generally at 22) is stopped. The portion of the paper web 5 falling into couch pit 20 is broken down and recycled back to the broke system (not shown). From couch roll 16 the paper web 5 is led into press section 22, where water is removed mechanically. Pickup felt 24 extends around pickup roll 26 and, as is typical in a closed draw system, is seated next to, and impinges on. wire mesh 4.
  • Press section 22 of a paper production line is shown.
  • Press section 22 is divided into the pickup felt section (shown generally at 28) and two press felt sections (shown generally at 30 and 32).
  • Press section 22 serves two primary functions: transferring paper web 5 from the forming section; and pressing paper web 5 to remove as much water as possible to minimize the costs of drying the web by steam in the drying section.
  • Paper web 5 is picked off wire mesh 4 and is carried by pickup felt 24 to first press felt section 30. Transfer of the paper web is accomplished by a vacuum transfer arrangement which works in conjunction with pickup felt 24.
  • Vacuum is provided by suction box 36 which is connected to a vacuum pump (shown as 38 in Figure 4), and which moves air through pickup felt 24 which is air permeable.
  • pickup roll 26 When press section 22 is in operation (the so-called “steady state") pickup roll 26 is in the "down" position labelled as "B". In this position, pickup roll 26 and pickup felt 24 actually impinge on paper web 5 which serves to assist in transfer of the paper web from forming wire 4 of the forming section to pickup felt 24 of press section 22.. However, when press section 22 is stopped, pickup roll 24 retracts into the "up” position, labelled as "A”. If paper web 5 is not released before pickup roll 26 is retracted, paper web 5 will tend to follow pickup roll 26. resulting in paper web jams, macro-folding of the paper web, and ultimately damage to parts of press section 22. downstream from the pickup roll 26.
  • the combined apparatus comprises suction box 36. vacuum pump 38, air pressure means
  • pressure controller 41 starts to close bleed line valve 47.
  • the negative pressure produced by vacuum pump 38 is applied to suction box 36 and paper web 5 is attracted to pickup felt 24.
  • the air pressure means can comprise a fan or the like.
  • Positive pressure from air pressure means 39 is applied to suction box 36 through bleed line 42 and is of sufficient magnitude to break the seal between pickup felt 24 and paper web 5.
  • pickup roll 26 typically takes in the order of 17 seconds to go from the down position "B " to the position where it no longer impinges on paper web 5. This is the critical period during which most of the paper web jamming, felt damage. etc. occurs. Accordingly, it is desirable that paper web 5 be blown off pickup felt 24 before retraction of pickup roll 26 is commenced.
  • a programmable control feedback system integral to the press section is commonly used to monitor several parameters while paper production is in the steady state. These parameters include, but are not limited to: the presence of sufficient vacuum in the suction boxes, the speed match between the forming section and the press section, and unloading of the centre roll doctor blade (shown in figure 2 as 46, with the centre roll labelled as 48). In the event that one of these parameters falls outside the desired ranged, engagement of the blowing apparatus can be automatically engaged by the control feedback system in the manner described above.
  • Figure 5 depicts a cross-sectional view of pickup roll 24 and the end of the forming section, highlighting the removal of paper web 5 from pickup felt 24 in accordance with the present invention.

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  • Paper (AREA)

Abstract

L'invention concerne une amélioration apportée au rouleau preneur (26) d'une partie de presse contenue dans une ligne de production de papier à tirage fermé, l'amélioration facilitant le retrait de la bande de papier du feutre preneur (24). Le rouleau preneur situé dans la partie presse comprend un rouleau perforé, une caisse aspirante (36) disposée longitudinalement dans le rouleau perforé ainsi qu'une pompe à dépression (38) reliée à la caisse aspirante. L'amélioration consiste en l'intégration d'un appareil de soufflage (39) se présentant sous la forme d'un ventilateur à l'intérieur de la caisse aspirante, et de moyens manuels ou automatiques pouvant être utilisés pour mettre en marche sélectivement la pompe à dépression ou le ventilateur selon les besoins. L'utilisation de l'appareil de soufflage permet d'amorcer rapidement la libération de la bande de papier du feutre preneur et d'éviter ainsi une détérioration du feutre preneur ou des matériaux de montage de la partie presse.
PCT/CA2000/000271 1999-04-01 2000-03-14 Appareil de liberation de bandes de papier pour rouleau preneur Ceased WO2000060165A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU32664/00A AU3266400A (en) 1999-04-01 2000-03-14 Paper web release apparatus for pickup roll

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US28348899A 1999-04-01 1999-04-01
US09/283,488 1999-04-01

Publications (1)

Publication Number Publication Date
WO2000060165A1 true WO2000060165A1 (fr) 2000-10-12

Family

ID=23086298

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2000/000271 Ceased WO2000060165A1 (fr) 1999-04-01 2000-03-14 Appareil de liberation de bandes de papier pour rouleau preneur

Country Status (2)

Country Link
AU (1) AU3266400A (fr)
WO (1) WO2000060165A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622492A (en) * 1947-07-26 1952-12-23 Beloit Iron Works Selective web transfer control for paper machinery
US3981084A (en) * 1972-06-19 1976-09-21 Fort Howard Paper Company Closed draw transfer system with gaseous pressure direction of web
US5087325A (en) * 1991-03-13 1992-02-11 Beloit Corporation Apparatus for manufacturing a dried web of paper

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2622492A (en) * 1947-07-26 1952-12-23 Beloit Iron Works Selective web transfer control for paper machinery
US3981084A (en) * 1972-06-19 1976-09-21 Fort Howard Paper Company Closed draw transfer system with gaseous pressure direction of web
US5087325A (en) * 1991-03-13 1992-02-11 Beloit Corporation Apparatus for manufacturing a dried web of paper

Also Published As

Publication number Publication date
AU3266400A (en) 2000-10-23

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