WO1991010775A1 - Dispositif pour guider les toiles d'une partie a deux toiles d'une machine a papier ou a carton - Google Patents

Dispositif pour guider les toiles d'une partie a deux toiles d'une machine a papier ou a carton Download PDF

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Publication number
WO1991010775A1
WO1991010775A1 PCT/EP1990/000088 EP9000088W WO9110775A1 WO 1991010775 A1 WO1991010775 A1 WO 1991010775A1 EP 9000088 W EP9000088 W EP 9000088W WO 9110775 A1 WO9110775 A1 WO 9110775A1
Authority
WO
WIPO (PCT)
Prior art keywords
screen
support surface
wire
guide track
sieve
Prior art date
Application number
PCT/EP1990/000088
Other languages
German (de)
English (en)
Inventor
Udo Grossmann
Original Assignee
J.M. Voith Gmbh
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 J.M. Voith Gmbh filed Critical J.M. Voith Gmbh
Publication of WO1991010775A1 publication Critical patent/WO1991010775A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/48—Suction apparatus
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F9/00—Complete machines for making continuous webs of paper
    • D21F9/003—Complete machines for making continuous webs of paper of the twin-wire type

Definitions

  • the invention relates to a device for guiding the screens of a twin-wire section of a paper or board machine according to the preamble of patent claim 1.
  • a device used to form a web fleece is known from DE-OS 31 38 133 (FIG. 3).
  • the nonwoven web is formed by feeding an aqueous fiber suspension layer onto the lower wire, with fibers initially being deposited on the lower wire in the area of the pre-dewatering elements only in the lower area of the suspension layer (by removing some of the water).
  • the upper area of the suspension layer remains liquid until it enters the twin-wire zone. This is where the dewatering begins at the top with the deposition of fibers on the underside of the top sieve, with a medium liquid suspension layer initially still being present between the fiber layers that form.
  • a curved section is initially provided in the twin-wire zone, which is followed by a wavy or zigzag-shaped section in the direction of wire travel.
  • These sections of the double screen zone are formed by upper and lower drainage boxes.
  • the upper sieve slides on a so-called “support surface” of the upper drainage box; the bottom wire slides on a so-called “wire guide track” of the lower drainage box.
  • the curved section of the support surface initially has a relatively strong curvature in the direction of wire travel, which then becomes weaker. Both screens of the twin-wire section are exposed to an adjustable tension acting in the longitudinal direction of the screen.
  • strips extending transversely to the wire running direction are fixedly arranged at a mutual distance.
  • the lower wire guide track also has strips which engage in the gaps between the strips of the upper support surface.
  • the sieves running between the support surface and the wire guide path must therefore follow an undulating path between the strips.
  • the extent of the amplitude of this path course can be adjusted by adjusting the strips of the wire guide path.
  • the amplitude of the course of the web determines the level of the surface pressure resulting from the screen tension on the partially still nonwoven web. This surface pressure (and thus the speed of the dewatering) depends on the fabric tension both in the curved section of the support surface and in the undulating section.
  • twin-wire section is described, based on the invention, and in the twin-wire zone of which the following is provided:
  • a drainage box which has on its underside an at least approximately flat "support surface” over which the top wire runs.
  • strip-shaped elements which extend transversely to the direction of wire travel and on which pressure members act flexibly, the pressure of which can be adjusted individually or in groups.
  • These strip-shaped elements also form an at least approximately flat "screen guide track 11 over which the lower screen runs.
  • the screen guide track and the support surface form a gap that tapers in the direction of screen travel.
  • the web fleece hangs on the (partially still liquid) web effective surface pressure (and thus the dewatering pressure) exclusively from the pressure that can be set in the above-mentioned pressure elements, whereas the screen tension has no influence on the dewatering pressure.
  • This known arrangement has the advantage that the surface pressure, the can be increased within the twin-wire zone from the initial low values in the direction of wire travel. Thus, thin, medium or very thick paper or cardboard webs can be produced, generally with satisfactory quality.
  • the surface pressure is set according to two different principles, namely on the essentially flat screen guide track solely by the pressure of the pressure elements, and then on the curved support surface solely by the level of the screen tension. It is particularly advantageous that both settings can be made independently of one another.
  • the curved additional drainage box can in principle be arranged either in the loop of the top wire or in the loop of the bottom wire. It is also possible to provide a certain distance between the flat part of the twin-wire zone and the curved drainage box. However, the configuration is preferred in which the curved support surface of the additional drainage box follows directly on the flat support surface. This largely prevents a drop in the drainage pressure when the web fleece runs from the flat to the curved section.
  • the support table, drainage box or the like. with the at least approximately flat support surface preferably lies in the upper sieve loop, so that the sieve guide track formed by the strip-shaped, resiliently supported elements is located in the lower sieve loop.
  • the reverse arrangement can also be chosen.
  • a lower wire 2 with a pre-dewatered web fleece 3 lying thereon and an upper wire 4 are present.
  • the endless loop of the lower wire 2 is not shown completely.
  • a headbox 30 with the emerging fiber suspension jet 31 is schematically indicated. This gradually forms the web fleece 3 on the bottom sieve 2 - initially under the effect of the pre-dewatering elements 32.
  • the thickness of the suspension layer increases, as indicated schematically , more and more.
  • a breast roll is designated 33, a screen tensioning roll 34 and a further screen guide roll 35.
  • the top wire 4 runs over wire guide rollers 36-39, the latter of which is designed as a wire tensioning roller.
  • the direction of wire travel is indicated by arrow 5.
  • twin-wire zone begins, in which the web fleece is located between the two screens.
  • the course of the twin-wire zone is determined by a device (which has two boxes 7 and 12), which is designated by a total of 6, for guiding the screens 2 and 4.
  • a box 7 Below the lower screen 2 there is a box 7, the upper side of which is a number transverse to Pneumatic pressure cushion 8 extending in the direction of screen travel.
  • a plate 9 On the pressure cushion 8 there is, for example, a plate 9, which is made flexible in the wire running direction by slots extending transversely to the wire running direction.
  • a plurality of upright, spacing strips 10 with a wear-resistant upper side are fastened in the plate 9.
  • the strips 10 extending transversely to the direction of wire travel 5 form a wire track 11 for the lower wire 2 on the upper side.
  • a drainage box 12 In the loop of the top wire 4 (and offset in the wire running direction by about 1/4 to 1/3 of the length of the wire guide track 11) there is a drainage box 12.
  • This has three successive chambers 13, 14 extending in the wire running direction and extending transversely to the direction of travel and 15, which are subjected to increasing vacuum in the direction of rotation.
  • the chambers 13 - 15 are delimited against the upper sieve 4 by strips 16 which extend transversely to the sieve running direction and are arranged at a mutual spacing. With their underside, the strips 16 form a support surface 17 for the upper sieve 4.
  • a suction box 18 which is subjected to negative pressure and whose upper side is convexly shaped.
  • the suction box 18 is provided with strips 10 which (at a mutual distance) extend transversely to the direction of wire travel and with their upper side form a slideway 20 for the lower wire 2.
  • the lower wire 2 extends before and after the twin wire zone in an approximately horizontal plane 21.
  • the lower wire 2 with the web fleece 3 thereon maintains its course in the wire plane 21.
  • the top wire 4 touches the web fleece 3 fed in at a relatively high layer height in the area of the section 22 of the wire guide web 11.
  • the bottom wire 2 is at a very small acute angle to the wire level 21 derived downwards.
  • the flat section 24 of the support surface 17 for the top wire 4 lying above this section 23 of the wire guide track 11 forms with the wire guide track a wedge-shaped gap tapering in the running direction.
  • the lower sieve 2 and the upper sieve 4 with web fleece 3 pass through the gap which continuously moves away from the sieve plane 21 in the direction of the sieve travel.
  • the strips 10 of the wire guide path 11 and the strips 16 of the support surface 17 preferably face each other with a gap.
  • the sieves 2 and 4 can therefore move as they run over the strips 10 and 16 into the opposite gap if there are 3 thickenings (chunks) in the web fleece.
  • both screens 2 and 4 with web fleece 3 are guided over a curved section 25 of the support surface 17.
  • the curvature of section 25 has a relatively large radius indicated by arrow 26; the length of the section in the direction of wire travel is approximately 1/3 of the length of the support surface 17.
  • the transition from the flat section 24 to the curved section 25 of the support surface 17 is continuous (tangential).
  • the curvature of section 25 of support surface 17 is shown in the set embodiment constant; however, it can also be designed with an increasing curvature in the direction of the wire.
  • both screens 2 and 4 with web fleece 3 approach the screen level 21, but without fully reaching it.
  • the screen level 21 is reached when the two screens 2 and 4 run with web fleece 3 via the slide 20 of the suction box 18. This has a curvature on the inlet side, due to which the slide track 20 reaches the screen plane 21 with its apex.
  • the radius of the curvature of the slideway 20 indicated by the arrow 27 is smaller than in the section 25 of the support surface 17. After the vertex of the slideway 20 of the suction box 18, this takes a course lying in the sieve plane 21. While the upper sieve 4 is lifted from the lower sieve 2 in the area of the slide of the slide 20, the lower sieve 2 with the web fleece 3 lying thereon continues in the sieve plane 21.
  • a strip 28 of the drainage box 12 is formed on the outlet side and a strip 29 of the suction box 18 on the inlet side with a greater curvature than in the rest of the area of the screen guide track 11 or the slide track 20.
  • the device 6 for guiding the screens 2 and 4 has the following effect on the web fleece 3:
  • the pressure that the strips 10 of the wire guide track 11 exert on the web fleece 3 enclosed between the two screens 2 and 4 as they run over the wire guide track 11 and the flat section 24 of the support surface 17 can be adjusted.
  • This pressure can be set individually in each pressure pad 8, increasing from low values in the direction of wire travel.
  • the pressure can also be set in groups of pressure pads. While the strips 16 of the support surface 17 are rigidly arranged to, the strips 10 of the wire guide track 11 are flexible at right angles to the wire level 21.
  • the further dewatering of the web fleece 3, which is reduced in layer height, is achieved solely by the longitudinal tension of the two screens 2 and 4 in conjunction with the negative pressure in the chamber 15 of the drainage box 12 and in the suction box 18.
  • the longitudinal tension alone of the lower wire 2 determines the dewatering pressure on the web fleece 3.
  • the longitudinal tension of the top wire 4 in cooperation with the negative pressure in the suction box 18 determines the degree of dewatering of the web fleece 3.
  • the negative pressure in the suction box 18 In addition to removing the liquid, it also serves to hold the web fleece 3 on the lower wire 2 when the top wire 4 moves away from the web fleece.

Landscapes

  • Paper (AREA)

Abstract

Le présent dispositif présente une surface d'appui plane (24) et un guidage de toiles (11) disposé de manière opposée, lesquels constituent une fente cunéiforme pour une toile supérieure (4) et pour une toile inférieure (2), avec, placée entre ces dernières, une sous-toile de guidage humide (3). Le guidage de toiles (11) est réalisé sur des barres (10) s'étendant transversalement au sens de déplacement des toiles et opposant de manière élastique une résistance à une déviation transversalement au plan de toile (21). L'égouttage de la sous-toile de guidage (3) se fait ici par une pression exercée sur la toile inférieure perpendiculairement au plan de toile. Après la fente, les toiles (2, 4) traversent une secteur courbé (25) de la surface d'appui, dans lequel l'égouttage de la sous-toile est obtenu notamment par la tension longitudinale de la toile extérieure (2).
PCT/EP1990/000088 1988-07-15 1990-01-17 Dispositif pour guider les toiles d'une partie a deux toiles d'une machine a papier ou a carton WO1991010775A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19883823966 DE3823966C2 (de) 1988-07-15 1988-07-15 Vorrichtung zum Führen der Siebe einer Doppelsiebpartie einer Papier- oder Kartonmaschine

Publications (1)

Publication Number Publication Date
WO1991010775A1 true WO1991010775A1 (fr) 1991-07-25

Family

ID=6358710

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1990/000088 WO1991010775A1 (fr) 1988-07-15 1990-01-17 Dispositif pour guider les toiles d'une partie a deux toiles d'une machine a papier ou a carton

Country Status (2)

Country Link
DE (1) DE3823966C2 (fr)
WO (1) WO1991010775A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993012292A1 (fr) * 1991-12-17 1993-06-24 J.M. Voith Gmbh Machine a papier a deux toiles
WO1994004749A1 (fr) * 1992-08-19 1994-03-03 Beloit Technologies, Inc. Machine pour former une bande a couches multiples
DE4342608A1 (de) * 1993-12-14 1995-03-30 Voith Gmbh J M Vorrichtung und Verfahren zur Steigerung des Bahntrockengehaltes einer Papierbahn
AU668097B2 (en) * 1992-08-19 1996-04-26 Beloit Technologies, Inc. A multi-ply web forming apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4005420C2 (de) * 1990-02-21 1995-06-08 Voith Gmbh J M Doppelsiebformer
DE102007000258A1 (de) 2007-05-08 2008-11-13 Voith Patent Gmbh Entwässerungsvorrichtung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146424A (en) * 1977-06-08 1979-03-27 Beloit Corporation Twin wire former with wire orientation control
EP0306759A1 (fr) * 1987-09-07 1989-03-15 Valmet-Ahlstrom Inc. Dispositif de contrôle des toiles dans une machine à papier ou carton
EP0371786A2 (fr) * 1988-12-01 1990-06-06 Valmet-Karhula Inc. Procédé et dispositif de formation de bandes continues

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI72157C (fi) * 1974-07-18 1987-04-13 Valmet Oy Dubbelviradel i pappersmaskin.
DE3138133C2 (de) * 1981-09-04 1986-03-06 Sulzer-Escher Wyss GmbH, 7980 Ravensburg Entwässerungseinheit für Langsieb-Papiermaschinen
DE3503242A1 (de) * 1985-01-31 1986-08-07 O. Dörries GmbH, 5160 Düren Vorrichtung zum fuehren der siebe einer doppelsiebpartie einer papier- oder kartonmaschine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146424A (en) * 1977-06-08 1979-03-27 Beloit Corporation Twin wire former with wire orientation control
EP0306759A1 (fr) * 1987-09-07 1989-03-15 Valmet-Ahlstrom Inc. Dispositif de contrôle des toiles dans une machine à papier ou carton
EP0371786A2 (fr) * 1988-12-01 1990-06-06 Valmet-Karhula Inc. Procédé et dispositif de formation de bandes continues

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993012292A1 (fr) * 1991-12-17 1993-06-24 J.M. Voith Gmbh Machine a papier a deux toiles
US5507918A (en) * 1991-12-17 1996-04-16 J.M. Voith Gmbh Twin-wire former
WO1994004749A1 (fr) * 1992-08-19 1994-03-03 Beloit Technologies, Inc. Machine pour former une bande a couches multiples
US5427654A (en) * 1992-08-19 1995-06-27 Beloit Technologies, Inc. Multi-ply web forming apparatus
AU668097B2 (en) * 1992-08-19 1996-04-26 Beloit Technologies, Inc. A multi-ply web forming apparatus
DE4342608A1 (de) * 1993-12-14 1995-03-30 Voith Gmbh J M Vorrichtung und Verfahren zur Steigerung des Bahntrockengehaltes einer Papierbahn

Also Published As

Publication number Publication date
DE3823966C2 (de) 1995-03-16
DE3823966A1 (de) 1990-01-25

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