EP1403423A1 - Caisse de tête avec générateur de courant tourbillonaire - Google Patents

Caisse de tête avec générateur de courant tourbillonaire Download PDF

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Publication number
EP1403423A1
EP1403423A1 EP03102711A EP03102711A EP1403423A1 EP 1403423 A1 EP1403423 A1 EP 1403423A1 EP 03102711 A EP03102711 A EP 03102711A EP 03102711 A EP03102711 A EP 03102711A EP 1403423 A1 EP1403423 A1 EP 1403423A1
Authority
EP
European Patent Office
Prior art keywords
swirl
headbox according
headbox
turbulence
lamella
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
EP03102711A
Other languages
German (de)
English (en)
Inventor
Wolfgang Ruf
Jürgen Prössl
Mathias Schwaner
Joachim Henssler
Ralf Wischmann
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.)
Voith Patent GmbH
Original Assignee
Voith Paper Patent 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 Voith Paper Patent GmbH filed Critical Voith Paper Patent GmbH
Publication of EP1403423A1 publication Critical patent/EP1403423A1/fr
Ceased legal-status Critical Current

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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
    • D21F1/02—Head boxes of Fourdrinier machines
    • D21F1/028—Details of the nozzle section
    • 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
    • D21F1/02—Head boxes of Fourdrinier machines

Definitions

  • the invention relates to a headbox with a turbulence generator and a nozzle.
  • Such a headbox serves to generate a machine-wide suspension jet in a machine used to produce a material web.
  • the material web formed from the suspension can in particular be a paper or cardboard web.
  • a corresponding headbox is described, for example, in the publications EP 0 211 607 A2 and DE 43 29 810 A1.
  • the headroom of the headboxes can a. for example, be divided by slats.
  • the slats currently used are essentially designed as flat plates.
  • the quality of the paper or cardboard is significantly influenced by relative movements between the fiber suspension and the sieve (s).
  • the formation and the burst pressure improve to an optimum with increasing difference between jet and sieve speed (
  • Shaking trestles are sometimes used in paper machines for graphic papers in order to improve the formation by additional shear stress.
  • this now has the disadvantage that the formation changes periodically at twice the shaking frequency.
  • the shaking frequency f For example, 300 1 / min and the machine speed v, for example 900 m / min, the screen moves between maximum and minimum lateral acceleration by 0.75 m.
  • the invention has for its object to provide a headbox of the type mentioned, with the properties of the fibrous web produced, in particular paper or cardboard, which require increased fiber orientation in the cross-machine direction, can be improved without noticeably affecting the properties of benefit from greater shear stress on the fiber suspension during sheet formation.
  • a swirl-generating device for introducing rotary currents having a flow component extending transversely to the machine direction into the fiber suspension within the nozzle space.
  • the swirl-generating device is installed and / or designed such that that there is no stowage point for the fiber suspension within the nozzle area.
  • the swirl-generating device can thus in particular be installed and / or designed in such a way that stagnation points at which fibers, filler, fine material, dirt and / or the like can accumulate or accumulate can be avoided.
  • the swirl-generating device can in particular comprise at least one lamella and / or at least one, in particular, fixed separating element, which, at least in regions, serves to generate the swirl.
  • the lamella or the separating element is preferably arranged between turbulence channel rows and / or gaps in the turbulence generator. Stagnation points at which fibers, filler, fine material, dirt and / or the like can accumulate or deposit are thus avoided again.
  • the designs described in EP 0 211 607 A2 have stagnation points which entail the risk of dirt accumulating or the formation of fabric specks.
  • the twist-producing internals are attached either to the side walls of the headbox or by means of tabs in the tubes of the flow grid.
  • spacers are described in this publication, which again also have stagnation points and, if attached to the side walls, may also cause problems with regard to possible deformations due to thermal changes in length.
  • the lamella or the separating element can extend in particular from the turbulence generator into the nozzle space.
  • the number of lamellae or separating elements can be selected, for example, as a function of the number of turbulence channel rows and / or gaps in the turbulence generator.
  • a preferred practical embodiment of the headbox according to the invention is characterized in that the lamella or the separating element is provided with incisions on its or its rear edge, as viewed in the direction of flow, and the resulting lamella or separating element ends serve to generate swirl.
  • the ends of the lamellae or separating elements can be limited, in particular with the formation of swirl blades.
  • the swirl blades can be restricted in the same direction, for example.
  • swirl blades are at least partially restricted in different directions.
  • the swirl blades can, for example, be alternately set in opposite directions.
  • the angle at which a respective swirl vane is set with respect to the non-set lamella or separating element part is advantageously in a range from 0 ° to a multiple of 360 ° (several complete revolutions) and preferably in a range from 30 ° to five times 360 ° (five full rotations).
  • the pitch of a respective swirl blade can vary in the machine direction.
  • the gradient of a respective swirl blade in the machine running direction can, for example, increase steadily.
  • the slope and / or the length of a respective swirl vane measured in the machine running direction can be selected in particular as a function of the respectively desired intensity of the rotary flow.
  • the lamella or the separating element is provided with at least one non-restricted swirl-producing guide element.
  • the division of the swirl blades or swirl-producing guide elements is preferably selected as a function of the division of the turbulence channels of the turbulence generator.
  • the division of the swirl blades or swirl-producing guide elements can in particular be an integer multiple or an integer fraction, e.g. B .... 3, 2, 1, 1/2, 1/3, 1/4, ..., correspond to the division of the turbulence channels of the turbulence generator.
  • the division of the swirl blades or swirl-producing guide elements can, for example, also be the same as the division of the turbulence channels of the turbulence generator.
  • the swirl vanes or swirl-producing guide elements can be aligned with the turbulence channels of the turbulence generator.
  • the swirl blades or swirl-producing guide elements viewed in the transverse direction, are offset relative to the turbulence channels of the turbulence generator.
  • the offset can correspond to half the division, for example.
  • the division of the swirl blades or swirl-producing guide elements can, however, in principle also be selected independently of the division of the turbulence channels of the turbulence generator.
  • the swirl blades or swirl-producing guide elements are designed so differently that there are different natural frequencies for them, so that vibrations are damped.
  • the swirl vanes or swirl-producing guide elements can at least partially also consist of vibration-damping material.
  • a respective lamella or a respective separating element is designed in such a way that forces introduced by the swirl vanes or the swirl-producing guide elements are absorbed and applied to holding elements of the headbox, such as e.g. the turbulence generator, a side wall delimiting the nozzle space, a separate support and / or the like are released.
  • the headbox can in principle be designed as a single-layer headbox or as a multi-layer headbox.
  • the number of fins used in the headbox depends on the number of turbulence channel lines of the turbulence generator or blocks.
  • the lateral edges of a respective lamella can have a respective distance from the relevant nozzle side wall.
  • an asymmetry with respect to the driver side and the drive side is also conceivable.
  • the slat ends can have any tip contour, e.g. B. have any conventional tip contour.
  • FIG. 1 shows a schematic plan view of part of a lamella 14 which is arranged in the nozzle space 10 of a headbox 12 and which serves in part to generate the swirl.
  • the lamella 14 extends from the last turbulence block of a turbulence generator 16 of the headbox 12 into the nozzle chamber 10, which is laterally delimited by nozzle walls 18, of which only one can be seen in FIG. 1.
  • An aperture 22 is provided in the area of the outlet gap of the relevant nozzle 20 of this headbox 12.
  • the direction of flow of the fiber suspension is indicated by "S". It corresponds to the machine direction L.
  • the headbox 12 comprises a swirl-generating device, here at least one lamella 14 serving at least in regions to generate the swirl, for introducing rotary flows into the fiber suspension within the nozzle space 10 having a flow component extending transversely to the machine direction L.
  • a swirl-generating device here at least one lamella 14 serving at least in regions to generate the swirl
  • the swirl-producing lamella 14 is provided with incisions 24 on its rear edge, as viewed in the direction of flow L, which results in a plurality of lamella ends 26, which in the present case are set at least in regions to produce swirl, with the formation of swirl vanes 28.
  • "I 4 " in FIG. 1 thus indicates the length of a respective swirl blade 28.
  • the lamella ends 26 can, for example, all be mutually limited in the same direction or alternately. If a plurality of lamellae 14 are installed in the headbox 12, then all, part of them or only one can be designed in the manner specified for generating swirl.
  • FIG. 2 shows exemplary shapes of the swirl vanes 28, the swirl vane shape in each case being shown before the cabinets. The respective setting directions are indicated below the respective swirl vane shape.
  • the lamella ends 28 can thus, for example, have a triangular shape (see FIGS. 2a, d, e with a triangle tapering in the machine direction L (see FIGS. 2a, d) or a triangle that widens in the machine direction L (see FIG. 2e), have a rectangular shape (cf. FIG. 2b), the shape of a truncated cone (cf. FIG. 2c) or a shape shown in FIG. 2f in which the initially generally strip-shaped lamella end 28 is provided with a semicircular recess 30 at the free end.
  • a respective lamella end 28 can also be jagged on its rear edge in the machine running direction L, for example.
  • the lamellae 14 can also have structured tips, for example.
  • FIG. 3 shows a schematic perspective illustration of a further embodiment of a lamella 14 used to generate the swirl.
  • the width B 1 of the non-restricted lamella section can, for example, be equal to the division of the turbulence channels of the turbulence generator 16.
  • this width B 1 of the non-set slat section can be, for example, the same, larger or smaller than the width B 2 of the free end of the set area or of the swirl vane 28.
  • the length L 1 of the non-restricted slat section can be ⁇ 0.
  • the respective swirl strength can be specified via the length L 2 of the restricted area or the swirl vane 28.
  • the length L 3 of the calming area is decisive for the calming that arises.
  • the free end of the restricted area or of the swirl vane 28 can be provided at a distance from the screen 22 (cf. FIG. 1).
  • the set row or swirl vanes 28 of the lamella 14 can be offset in the transverse direction to the turbulence channels of the turbulence generator 16, wherein the offset can correspond in particular to half the division of the turbulence channels of the turbulence generator 16.
  • FIG. 4 shows a schematic representation of another embodiment of a lamella 14, in which this lamella 14 is provided with attached and / or attached twist scoops 28 '.
  • the headbox in question can in particular at least essentially be designed as described in connection with FIG. 1.
  • the swirl vane 28 'attached or attached can in principle, for example, at least essentially be designed in the same way as was described in connection with the swirl vane 28 by way of example with reference to FIG. 1.
  • FIG. 5 shows a schematic front view of a further embodiment of a lamella 14, which in the present case, however, has a "straight", i.e. is not provided twist-generating guide elements 32 is provided.
  • FIG. 6 shows a schematic side view of a guide element 32 of the design according to FIG. 5 which does not form a swirl.
  • the machine direction is in each case “MD”
  • the transverse direction is in each case “CD”
  • VD vertical direction
  • FIG. 7 shows a schematic sectional partial view of a multi-layer headbox 12 with at least one separating element 34 and several swirl-producing lamellae 14.
  • a respective separating element 34 can also be designed as a swirl-generating element in the manner described above in connection with the lamellae or can be provided with swirl blades.

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EP03102711A 2002-09-27 2003-09-05 Caisse de tête avec générateur de courant tourbillonaire Ceased EP1403423A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10245157 2002-09-27
DE2002145157 DE10245157A1 (de) 2002-09-27 2002-09-27 Stoffauflauf

Publications (1)

Publication Number Publication Date
EP1403423A1 true EP1403423A1 (fr) 2004-03-31

Family

ID=31969649

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03102711A Ceased EP1403423A1 (fr) 2002-09-27 2003-09-05 Caisse de tête avec générateur de courant tourbillonaire

Country Status (2)

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EP (1) EP1403423A1 (fr)
DE (1) DE10245157A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1452640A2 (fr) * 2003-02-27 2004-09-01 Voith Paper Patent GmbH Caisse de tête

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0211607A2 (fr) * 1985-07-30 1987-02-25 Seishi Gijutsu Kenkyu Kumiai Caisse de tête pour une machine à papier
EP0769586A2 (fr) * 1995-10-20 1997-04-23 Institute of Paper Science and Technology, Inc. Procédé et dispositif pour l'amélioration des qualités de formage d'un papier ou carton
DE10150951A1 (de) * 2001-10-16 2002-02-28 Voith Paper Patent Gmbh Verfahren zur Verbesserung der Eigenschaften einer aus mindestens einer Faserstoffsuspension hergestellten Faserstoffbahn und Stoffauflauf

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10102198A1 (de) * 2001-01-18 2002-08-22 Voith Paper Patent Gmbh Former sowie Stoffauflauf für einen solchen Former

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0211607A2 (fr) * 1985-07-30 1987-02-25 Seishi Gijutsu Kenkyu Kumiai Caisse de tête pour une machine à papier
EP0769586A2 (fr) * 1995-10-20 1997-04-23 Institute of Paper Science and Technology, Inc. Procédé et dispositif pour l'amélioration des qualités de formage d'un papier ou carton
DE10150951A1 (de) * 2001-10-16 2002-02-28 Voith Paper Patent Gmbh Verfahren zur Verbesserung der Eigenschaften einer aus mindestens einer Faserstoffsuspension hergestellten Faserstoffbahn und Stoffauflauf

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1452640A2 (fr) * 2003-02-27 2004-09-01 Voith Paper Patent GmbH Caisse de tête
EP1452640A3 (fr) * 2003-02-27 2004-11-17 Voith Paper Patent GmbH Caisse de tête

Also Published As

Publication number Publication date
DE10245157A1 (de) 2004-04-08

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