EP1953296B1 - Method for manufacturing a fibrous web and twin wire former for carrying out the method - Google Patents

Method for manufacturing a fibrous web and twin wire former for carrying out the method Download PDF

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Publication number
EP1953296B1
EP1953296B1 EP08150696A EP08150696A EP1953296B1 EP 1953296 B1 EP1953296 B1 EP 1953296B1 EP 08150696 A EP08150696 A EP 08150696A EP 08150696 A EP08150696 A EP 08150696A EP 1953296 B1 EP1953296 B1 EP 1953296B1
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EP
European Patent Office
Prior art keywords
fabric
suction
dewatering box
twin wire
zone
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Not-in-force
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EP08150696A
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German (de)
French (fr)
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EP1953296A1 (en
Inventor
Thomas Dr. Jaschinski
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Voith Patent GmbH
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Voith Patent GmbH
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Publication of EP1953296A1 publication Critical patent/EP1953296A1/en
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Publication of EP1953296B1 publication Critical patent/EP1953296B1/en
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    • 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 method for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension in a twin-wire former of a machine for producing the fibrous web with a wedge-shaped inlet gap having twin-wire zone, which is at least partially formed by two continuous endless sieves of which the first, over a preferably positionable inlet roller guided and then the already introduced pulp suspension covering sieve in the twin-wire zone is guided over a plurality of mutually spaced rigidly on a preferably positionable and several suction zones comprehensive drainage crate ledges and of which the second, the introduced pulp suspension receiving Sieve in the twin-wire zone via several and mutually the strips of preferably positionable and several suction zones comprehensive drainage box arranged Leis is guided, which are supported by means of resilient elements and which are pressed with a selectable force against the second wire, wherein the first, the introduced pulp suspension not yet covering sieve immediately before his leadership on the rigidly arranged on the drainage box strips by the effective range at least a suction shoe arranged
  • the invention relates to a twin-wire former of a machine for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension according to the preamble of independent claim 8.
  • twin-wire former is known, for example, from the International Application WO 2004/018768 A1 in an embodiment of a so-called “hybrid former" known.
  • This type of former has the characteristic that uncontrolled and strong air currents, in particular before and in the wedge-shaped inlet gap, at higher speeds, such as over 1200 m / min, lead to appreciable impairments of the producible quality in the fibrous web to be produced, such as, for example a deterioration of the residual variance of the basis weight cross-section or to disturbances in the sheet structure.
  • the disorders in the leaf structure are commonly referred to as bear paws and are known to result from large-scale formation disorders.
  • bright spots on the top of the fibrous web to be formed may occur, which are caused inter alia by entrained air or thrown off drops.
  • twin-wire former passes over a forming shoe, which is arranged rigidly on a stationary dewatering box and whose wire guide surface has a fixed convex radius of curvature in the range from 600 to 4,000 mm, preferably from 800 to 3,000 mm.
  • a forming shoe which is arranged rigidly on a stationary dewatering box and whose wire guide surface has a fixed convex radius of curvature in the range from 600 to 4,000 mm, preferably from 800 to 3,000 mm.
  • the higher speeds are in this case in a range of over 1,200 m / min, preferably of over 1,400 m / min, in particular of over 1,600 m / min.
  • the at least one directly to the drainage box suction shoe is formed adjustable in position.
  • the drainage box is thus formed together with the suction shoe as a functional unit and the entrained substances may include, for example, white water or the like.
  • the suction shoe and the subsequent suction zones of the dewatering box form a functional unit, wherein the actual dewatering of the pulp suspension through the first sieve takes place only on the first suction zone and so, for example, a against the Sieblaufraum back flowing pulp suspension can be sucked from the suction shoe arranged in front of the first suction zone.
  • disturbances in sheet formation are effectively counteracted.
  • the structure of a fibrous mat in the initial region ie the area of deposition of fibers on the first sieve on the first suction zone by means of the constantly applied, adjustable and adjustable vacuum, the drainage can be actively influenced, whereby the web formation is positively influenced.
  • the surface of the fibrous web formed and the further web structure are influenced particularly positively by the defined deposition of the outer and the following fibrous layers by means of the above-described arrangement and sequence of the suction zones and of the regulatable and adjustable vacuum of the respective suction zone or suction zones.
  • speeds of more than 1,200 m / min preferably more than 1,400 m / min, in particular of more than 1,600 m / min, can be achieved in the production of fibrous webs with sufficient qualities, since no boundary layers build up before the actual dewatering elements can.
  • the suction shoe which can be adjusted in its position and is arranged directly on the drainage box is arranged in such a way that the fibrous suspension introduced and having a layer height accumulates on the first sieve in the first suction zone of the drainage box, ie is covered by it ,
  • the suction shoe can sufficiently condition the first screen guided past it without touching the boundary layer of the pulp suspension.
  • the suction shoe which can be adjusted in its position and is arranged directly on the drainage box, is preferably arranged such that the introduced pulp suspension having a layer height is at the beginning of the first suction zone of the dewatering box runs on the first sieve, so it is covered by him.
  • the first suction zone is enveloped by the pulp suspension and the second wire and so completely sealed, that the height of the vacuum formed in the first suction zone is adjustable and adjustable. This in turn has a positive effect on the achievable quality of the fibrous web to be produced.
  • the layer height of the pulp suspension is preferably measured using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) and the measurement signal obtained is preferably used to control the gap width formed between the two screens, wherein the gap width of the is the vertical distance of the first wire at the run-off point from the inlet roll of the second wire.
  • the multiple suction zones comprehensive drainage box can be raised or lowered together with directly arranged suction shoe.
  • the inlet sieve leading the first sieve the suction shoe emptying the first sieve of entrained substances and removing both the emptied substances and the air entrained by the first sieve, and the multi-suction drainage box be positioned independently of each other. In principle, therefore, any operating modes and parameters necessary for achieving good qualities can be set.
  • the second sieve is guided mutually the first suction zone of the dewatering box over several bars, which are supported by means of resilient elements and which are pressed with a selectable force against the second sieve.
  • further impulses are introduced early in the pulp suspension, which improve the drainage and formation of the same noticeably.
  • the second sieve can be guided mutually all suction zones of the dewatering box over several bars, which are supported by means of resilient elements and which are pressed with a selectable force against the second sieve.
  • the object of the invention is achieved in a twin-wire former of the type mentioned above in that the at least one suction shoe arranged directly on the drainage box is adjustable in its position.
  • the drainage box is thus formed together with the suction shoe as a functional unit and the entrained substances may include, for example, white water or the like.
  • the suction shoe has an open suction surface in the range of 10 to 90%, preferably from 30 to 49%. These areas ensure adequate suction of both the first sieve and the free inlet gap.
  • the suction shoe may preferably have at least one suction pad which has at least one slotted covering or a plurality of slidable strips includes.
  • the individual strips can be mounted on a convexly curved suction box, the strip distances are freely selectable and different slot widths can be adjusted.
  • the suction shoe preferably has a convex radius of curvature in the range from 300 to 6,000 mm, preferably from 800 to 3,000 mm.
  • This convex radius of curvature promotes a stable sifting run, ensures defined run-in conditions and ensures a good sieve consolidation.
  • the convex radius of curvature predetermines the converging inlet gap with the aim of softer dewatering of the pulp suspension. Also, the pulp suspension located on the second wire undergoes defined impact conditions on the first wire.
  • the first suction zone of the dewatering box has an open suction area in the range from 10 to 90%, preferably from 30 to 49%, and / or a convex radius of curvature in the range from 300 to 10,000 mm, preferably from 800 to 6,000 mm.
  • Said open suction surface is sufficient to guide the first wire on the remaining surface still safe and to support accordingly. In addition, optimal suction and drainage can be ensured.
  • the twin-wire former according to the invention can in principle be designed as a hybrid former known per se, wherein the second sieve receiving the introduced pulp suspension is preferably a Fourdrinier wire, which is guided over a pre-dewatering zone prior to entry into the twin-wire zone.
  • the twin-wire former according to the invention may be formed as a gap former known per se, wherein the inlet roller leading the first screen is preferably a breast roller and wherein the twin-wire zone preferably substantially horizontal or approximately horizontally, at a pitch angle to the horizontal, or vertical or approximately vertical.
  • FIG. 1 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a hybrid former.
  • the twin-wire zone 2 extends essentially horizontally or approximately horizontally.
  • the twin-wire former 1 is part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.
  • the twin-wire former 1 comprises two continuous endless sieves, a first sieve 4, which is also referred to as an upper sieve, and a second sieve 5, which is also referred to as a Fourdrinier sieve, lower sieve or carrier sieve.
  • the sieves 4, 5 form at least in sections with each other, the twin-wire zone 2, which has a wedge-shaped inlet gap 6 for the pulp suspension 3.
  • the introduction, not shown, of the pulp suspension 3 onto the second wire 5 takes place by means of at least one known but not explicitly illustrated head box 7, whose headbox nozzle 8 can moreover be provided with at least one lamella 9 for the purpose of influencing and improving the beam quality (cf. FIGS. 2 and 3 ).
  • the first screen 4 is guided over a preferably positionable inlet roller 10, whose possible positioning is indicated by means of a symbolic motion double arrow A. Subsequently, the first sieve 4 in the twin-wire zone 2 is guided over a plurality of strips 12, which are arranged rigidly at a mutual distance on a preferably positionable and several suction zones Z11.x comprehensive drainage box 11. The positionability of the dewatering box 11 is indicated by means of a symbolic movement double arrow B.
  • the drainage box 11 has a total of three suction zones Z11.1, Z11.2 and Z11.3, which are arranged directly one behind the other and which can be acted upon by different suppressions pU11.1, pU11.2 and pU11.3.
  • the first wire 4 covers during its course of the first sieve 4 from the inlet roller 10 to the dewatering box 11 from the already introduced on the second sieve 5 pulp suspension 3 from.
  • the second and the introduced pulp suspension 3 receiving sieve 5 is guided in the twin-wire zone 2 over a plurality of strips 13 which are supported by resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2.
  • the strips 13 are mutually arranged on the strips 12 of the second suction zones Z11.2 of the drainage box 11.
  • the second sieve 5 is a Fourdriniersieb 5.1, which before entering the Twin-wire zone 2 is guided over a merely indicated, but known to those skilled pre-dewatering zone 15.
  • the introduced pulp suspension 3 is not yet covered sieve 4 immediately before its leadership on the rigidly arranged on the drainage box 11 strips 12 by the effective range W at least one of the drainage box 11 preferably in its position adjustably arranged suction shoe 16, which due the preferably controllable / controllable aspiration of the effective range W with a negative pressure pU16 empties the first sieve 4 of entrained substances and removes both the deflated substances and the entrained air from the first sieve 4.
  • the preferably controllable / suction with the vacuum pU16 is indicated by an arrow C.
  • the suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11.
  • the positionability of the suction shoe 16 is indicated by means of a movement double arrow D. Of course, it can also be positioned together with the drainage box 11 due to an at least temporary coupling together.
  • the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.
  • the suction shoe 16 is arranged sealingly with respect to the inlet roller 10, so that only the air introduced into the inlet gap 6 and not the ambient air is sucked in and removed behind the suction shoe.
  • the seal can due to a enschenden geometric design of the Both components 10, 16, but also due to additional fittings, such as sealing elements and the like, can be effected.
  • the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm.
  • the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips.
  • the suction pad 17 is indicated only by dashed lines.
  • the suction shoe 16 which can be adjusted in its position and is arranged directly on the dewatering box 11, is arranged in such a way that the fibrous suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP in the first suction zone Z11.1 of the dewatering box 11 So it is covered.
  • the suction shoe 16 which can be adjusted in position and is arranged directly on the drainage box 11, can also be arranged in such a way that the fibrous suspension 3 having a layer height H3 has an impact point ATP at the beginning of the first suction zone Z11.1 of FIG Drainage box 11 runs onto the first sieve 4, so it is covered by him.
  • a merely indicated device 18 for measuring the layer height H3 of the pulp suspension 3 using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) is provided, wherein the measurement signal obtained for controlling / regulating the between the two Seven trained gap width S is used.
  • the gap width S is here by definition the vertical distance of the first sieve 4 at the drain point P of the inlet roll 10 from the second sieve 5.
  • the gap width S can be adjusted by the inlet sieve 10 leading the first sieve 4 emptying the first sieve 4 of entrained substances and both the emptied substances and the air entrained by the first sieve 3 removing suction shoe 16 and the plurality of suction zones Z11.x comprehensive drainage box 11 are independently positionable (double movement arrows A, B and D).
  • the first suction zone Z11.1 of the dewatering box 11 also has an open suction surface F11.1 in the range of 10 to 90%, preferably 30 to 49%, and a convex radius of curvature K11.1 in the range of 300 to 10,000 mm, preferably 800 up to 6,000 mm, on.
  • FIG. 2 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a gap former.
  • the twin-wire zone 2 extends substantially vertically or approximately vertically. It can also extend in a further embodiment at a pitch angle to the horizontal.
  • This twin-wire former 1 is also part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.
  • the twin-wire former 1 comprises two continuous endless sieves, a first sieve 4, which is also referred to as a top sieve, and a second sieve 5, which is also referred to as a bottom sieve or a support sieve.
  • the sieves 4, 5 form at least in sections with each other the twin-wire zone 2, which has a wedge-shaped inlet gap 6 for the pulp suspension 3.
  • the headbox 8 also can be provided with at least one blade 9 for influencing and improving the beam quality.
  • the first sieve 4 is guided over a preferably positionable inlet roller 10 in the form of a breast roller whose possible positioning capability is indicated by means of a symbolic movement double arrow A. Subsequently, the first sieve 4 in the twin-wire zone 2 is guided over a plurality of strips 12, which are arranged rigidly at a mutual distance on a preferably positionable and several suction zones Z11.x comprehensive drainage box 11. The positionability of the dewatering box 11 is indicated by means of a symbolic movement double arrow B.
  • the drainage box 11 has a total of three suction zones Z11.1, Z11.2 and Z11.3, which are arranged directly one behind the other and which can be acted upon by different suppressions pU11.1, pU11.2 and pU11.3.
  • the first wire 4 covers during its course of the first sieve 4 from the inlet roller 10 to the dewatering box 11 from the already introduced on the second sieve 5 pulp suspension 3 from.
  • the second and the introduced pulp suspension 3 receiving sieve 5 is guided in the twin-wire zone 2 over a plurality of strips 13 which are supported by resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2.
  • the strips 13 are arranged at least mutually the strips 12 of the two suction zones Z11.1 and Z11.2 of the drainage box 11. Expanding the strips 13 may also be mutually the strips 12 of the third suction Z11.3 the drainage box 11 arranged (dashed line).
  • the preferably controllable / suction is indicated by means of an arrow C.
  • the suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11.
  • the positionability of the suction shoe 16 is indicated by means of a movement double arrow D.
  • the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.
  • the suction shoe 16 is arranged sealingly with respect to the inlet roller 10, so that only the air introduced into the inlet gap 6 and not the ambient air is sucked in and removed behind the suction shoe.
  • the seal can be effected due to a endreamenden geometric design of the two components 10, 16, but also due to additional fittings, such as sealing elements and the like.
  • the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm.
  • the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips.
  • the suction pad 17 is indicated only by dashed lines.
  • the suction shoe 16 which can be adjusted in position and is arranged directly on the drainage box 11, is arranged such that the fibrous stock suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP at the beginning of the first suction zone Z11.1 of the drainage box 11, is covered by him so.
  • the suction shoe 16 which can be adjusted in position and disposed directly on the drainage box 11, can also be arranged such that the introduced pulp suspension 3 having a layer height H3 at an impact point ATP in the first suction zone Z11.1 of the drainage box 11 accumulates on the first sieve 4, so it is covered by him.
  • a merely indicated device 18 for measuring the layer height H3 of the pulp suspension 3 using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) is provided, wherein the measurement signal obtained for controlling / regulating the between the two Seven trained gap width S is used.
  • the gap width S is here by definition the vertical distance of the first sieve 4 at the drain point P of the inlet roll 10 of the second sieve 5.
  • the gap width S can be adjusted so that the first sieve 4 leading inlet roll 10, which is the first sieve 4 emptying of entrained substances and both the deflated substances and the air entrained by the first screen 3 removing suction shoe 16 and the plurality of suction zones Z11.x comprehensive drainage box 11 are independently positionable (double movement arrows A, B and D).
  • the first suction zone Z11.1 of the dewatering box 11 also has an open suction surface F11.1 in the range of 10 to 90%, preferably 30 to 49 %, and a convex curvature radius K11.1 in the range of 300 to 10,000 mm, preferably 800 to 6,000 mm.
  • FIG. 3 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a gap former.
  • the twin-wire zone 2 extends substantially vertically or approximately vertically. It can also extend in a further embodiment at a pitch angle to the horizontal.
  • This twin-wire former 1 is also part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.
  • the illustrated twin-wire former 1 essentially corresponds to that in FIG FIG. 2 shown twin-wire former 1, so that hereby with regard to its description to the description of the in the FIG. 2 shown twin-wire former 1 is referenced.
  • the second and the introduced pulp suspension 3 receiving sieve 5 of the twin-wire former 1 of FIG. 3 is guided in the twin-wire zone 2 over a plurality of strips 13, which are supported by means of resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2.
  • the strips 13 are mutually arranged on the strips 12 of the second suction zones Z11.2 of the drainage box 11.
  • a dewatering element 19 known to the person skilled in the art is arranged, which acts on the pulp suspension 3 through the second wire 5.
  • the preferably controllable / suction is indicated by means of an arrow C.
  • the suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11.
  • the positionability of the suction shoe 16 is indicated by means of a movement double arrow D.
  • the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.
  • the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm.
  • the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips.
  • the suction pad 17 is indicated only by dashed lines.
  • the suction shoe 16 which can be adjusted in position and is arranged directly on the drainage box 11, is arranged such that the fibrous stock suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP at the beginning of the first suction zone Z11.1 of the drainage box 11, so covered by him.
  • twin-wire former 1 is suitable in a particular extent for carrying out the method according to the invention for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension 3 in a Doppelsiebformer 1 a machine for producing the fibrous web with a wedge-shaped inlet gap 6 having twin-wire 2 , which is at least partially formed by two continuous endless screens 4, 5, of which the first, guided over a preferably positionable inlet roller 10 and then the already introduced pulp suspension 3 covering sieve 4 in the twin-wire zone 2 over a plurality of spaced apart rigidly at a preferably positionable and several suction zones Z11.1, Z11.2, Z11.3 comprehensive drainage box 11 arranged strips 12 is guided and of which the second, the introduced pulp suspension 3 receiving sieve 5 in the twin-wire zone 2 via me Leaders and mutually the strips 12 of the preferably positionable and a plurality of suction Z11.1, Z11.2, Z11.3 comprehensive drainage box 11 arranged strips 13 is guided, which are supported by resilient elements
  • twin-wire former 1 to a special extent for carrying out the dependent method claims.
  • a method and a twin-wire former of the aforementioned types are improved by the invention so that a pulp suspension can be dewatered even at higher speeds and also in producing a high-quality fibrous web and that disturbances during the sheet forming process can be actively counteracted.
  • the higher speeds are in this case in a range of over 1,200 m / min, preferably of over 1,400 m / min, in particular of over 1,600 m / min.

Abstract

The method involves guiding a filter (4) that does not cover an inserted fibrous material suspension before its guidance over blocks (12) arranged at a drainage box (11) through an effective region (W) of a suction shoe (16). The suction shoe is adjustably arranged at the effective region in its position (D). Carried substances are evacuated from the filter by the suction shoe as a result of controlled and regulated suction of the effective region. The evacuated substances and the air carried through the filter are removed by the suction shoe.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension in einem Doppelsiebformer einer Maschine zur Herstellung der Faserstoffbahn mit einer einen keilförmigen Einlaufspalt aufweisenden Doppelsiebzone, die von zwei umlaufenden endlosen Sieben zumindest streckenweise gebildet wird, von denen das erste, über eine vorzugsweise positionierbare Einlaufwalze geführte und anschließend die bereits eingebrachte Faserstoffsuspension abdeckende Sieb in der Doppelsiebzone über mehrere mit gegenseitigem Abstand starr an einem vorzugsweise positionierbaren und mehrere Saugzonen umfassenden Entwässerungskasten angeordnete Leisten geführt wird und von denen das zweite, die eingebrachte Faserstoffsuspension aufnehmende Sieb in der Doppelsiebzone über mehrere und gegenseitig der Leisten des vorzugsweise positionierbaren und mehrere Saugzonen umfassenden Entwässerungskastens angeordnete Leisten geführt wird, die mittels nachgiebiger Elemente abgestützt werden und die mit einer wählbaren Kraft gegen das zweite Sieb angedrückt werden, wobei das erste, die eingebrachte Faserstoffsuspension noch nicht abdeckende Sieb unmittelbar vor seiner Führung über die starr an dem Entwässerungskasten angeordneten Leisten durch den Wirkbereich wenigstens eines an dem Entwässerungskasten angeordneten Saugschuhs geführt wird, welcher infolge der vorzugsweise steuer-/regelbaren Besaugung des Wirkbereichs das erste Sieb von mitgeführten Substanzen entleert und sowohl die entleerten Substanzen als auch die vom ersten Sieb mitgeführte Luft entfernt.The invention relates to a method for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension in a twin-wire former of a machine for producing the fibrous web with a wedge-shaped inlet gap having twin-wire zone, which is at least partially formed by two continuous endless sieves of which the first, over a preferably positionable inlet roller guided and then the already introduced pulp suspension covering sieve in the twin-wire zone is guided over a plurality of mutually spaced rigidly on a preferably positionable and several suction zones comprehensive drainage crate ledges and of which the second, the introduced pulp suspension receiving Sieve in the twin-wire zone via several and mutually the strips of preferably positionable and several suction zones comprehensive drainage box arranged Leis is guided, which are supported by means of resilient elements and which are pressed with a selectable force against the second wire, wherein the first, the introduced pulp suspension not yet covering sieve immediately before his leadership on the rigidly arranged on the drainage box strips by the effective range at least a suction shoe arranged on the dewatering box is guided, which empties the first sieve of entrained substances as a result of the preferably controllable / controllable suction of the effective area and removes both the emptied substances and the entrained air from the first sieve.

Weiterhin betrifft die Erfindung einen Doppelsiebformer einer Maschine zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension gemäß dem Oberbegriff des unabhängigen Patentanspruchs 8.Furthermore, the invention relates to a twin-wire former of a machine for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension according to the preamble of independent claim 8.

Ein derartiger Doppelsiebformer ist zum Beispiel aus der Internationalen Anmeldung WO 2004/018768 A1 in Ausgestaltung eines so genannten "Hybridformers" bekannt.Such a twin-wire former is known, for example, from the International Application WO 2004/018768 A1 in an embodiment of a so-called "hybrid former" known.

Dieser Formertyp weist die Eigenschaft auf, dass unkontrollierte und starke Luftströmungen, insbesondere vor dem und in dem keilförmigen Einlaufspalt, bei höheren Geschwindigkeiten, wie beispielsweise über 1.200 m/min, zu merklichen Beeinträchtigungen der herstellbaren Qualität in der herzustellenden Faserstoffbahn führen, wie zum Beispiel zu einer Verschlechterung der Restvarianz des Flächengewichtsquerprofils oder zu Störungen im Blattgefüge. Die Störungen im Blattgefüge werden gemeinhin als Bärentatzen bezeichnet und resultieren bekanntermaßen aus großflächigen Formationsstörungen. Zudem können helle Flecken an der Oberseite der zu bildenden Faserstoffbahn entstehen, die unter anderem durch mitgeführte Luft oder abgeschleuderte Tropfen verursacht werden.This type of former has the characteristic that uncontrolled and strong air currents, in particular before and in the wedge-shaped inlet gap, at higher speeds, such as over 1200 m / min, lead to appreciable impairments of the producible quality in the fibrous web to be produced, such as, for example a deterioration of the residual variance of the basis weight cross-section or to disturbances in the sheet structure. The disorders in the leaf structure are commonly referred to as bear paws and are known to result from large-scale formation disorders. In addition, bright spots on the top of the fibrous web to be formed may occur, which are caused inter alia by entrained air or thrown off drops.

Weiterhin sind die beiden Siebe des aus der WO 2004/018768 bekannten.Furthermore, the two sieves of the WO 2004/018768 known.

Doppelsiebformere zu Beginn der Doppelsiebzone über einen Formierschuh geführt, der starr an einem ortsfesten Entwässerungskasten angeordnet ist und dessen Siebführungsfläche einen fixen konvexen Krümmungsradius im Bereich von 600 bis 4.000 mm, vorzugsweise von 800 bis 3.000 mm, aufweist. Bei einer derartigen Anordnung ist es quasi unmöglich, insbesondere bei hohen Geschwindigkeiten, die Grenzschicht der Faserstoffsuspension mit der von dem Sieb umschlungenen konvexen Saugzone präzise zu treffen, da die Grenzschicht der Faserstoffsuspension nicht eben und vollständig plan ist. Somit können mit dieser Anordnung die vorstehend genannten Nachteile nicht zufrieden stellend beseitigt werden.At the beginning of the twin-wire zone, twin-wire former passes over a forming shoe, which is arranged rigidly on a stationary dewatering box and whose wire guide surface has a fixed convex radius of curvature in the range from 600 to 4,000 mm, preferably from 800 to 3,000 mm. With such an arrangement, it is virtually impossible, especially at high speeds, to precisely strike the boundary layer of the pulp suspension with the convex suction zone wrapped around the sieve, since the boundary layer of the pulp suspension is not flat and completely flat. Thus, with this arrangement, the above-mentioned disadvantages can not be satisfactorily eliminated.

Es ist also Aufgabe der Erfindung, ein Verfahren und einen Doppelsiebformer der eingangs genannten Arten derart zu verbessern, dass eine Faserstoffsuspension auch bei höheren Geschwindigkeiten und überdies bei Herstellung einer qualitativ hochwertigen Faserstoffbahn entwässert werden kann und dass Störungen während des Blattbildungsprozesses aktiv entgegengewirkt werden können. Die höheren Geschwindigkeiten liegen hierbei in einem Bereich von über 1.200 m/min, vorzugsweise von über 1.400 m/min, insbesondere von über 1.600 m/min.It is therefore an object of the invention to improve a method and a twin-wire former of the aforementioned types such that a pulp suspension can be dewatered even at higher speeds and, moreover, in the production of a high-quality fibrous web and that disturbances can be actively counteracted during the sheet forming process. The higher speeds are in this case in a range of over 1,200 m / min, preferably of over 1,400 m / min, in particular of over 1,600 m / min.

Diese Aufgabe wird bei einem Verfahren der eingangs genannten Art erfindungsgemäß dadurch gelöst, dass der wenigstens eine an dem Entwässerungskasten unmittelbar angeordnete Saugschuh in seiner Position einstellbar ausgebildet wird. Der Entwässerungskasten wird also zusammen mit dem Saugschuh als funktionelle Einheit ausgebildet und die mitgeführten Substanzen können beispielsweise Siebwasser oder dergleichen umfassen.This object is achieved in a method of the type mentioned in the present invention that the at least one directly to the drainage box suction shoe is formed adjustable in position. The drainage box is thus formed together with the suction shoe as a functional unit and the entrained substances may include, for example, white water or the like.

Die erfindungsgemäße Aufgabe wird hiermit vollständig gelöst.The object of the invention is hereby completely solved.

Durch die weitgehende Reduzierung beziehungsweise vollständige Beseitigung sowohl von in dem ersten Sieb mitgeführten Substanzen als auch von mitgeführter Luft samt unkontrollierten Luftströmungen wird maßgeblich dazu beigetragen, eine Faserstoffbahn mit überdurchschnittlichen Qualitäten herstellen zu können. Diese Qualitäten umfassen insbesondere das Flächengewichtsquerprofil und die Formation. Zudem führt die sich an den Einlaufspalt in Sieblaufrichtung unmittelbar anschließende Doppelsiebzone zu einer weiteren Formationsverbesserung in der herzustellenden Faserstoffbahn.By largely reducing or completely eliminating both entrained in the first sieve substances as well as entrained air, including uncontrolled air currents is significantly contributed to be able to produce a fibrous web with above-average qualities. These qualities include in particular the basis weight cross profile and the formation. In addition, the twin-wire zone immediately adjoining the inlet gap in the wire-winding direction leads to a further formation improvement in the fibrous web to be produced.

Für die Erfindung ist also wesentlich, dass der Saugschuh und die nachfolgenden Saugzonen des Entwässerungskastens eine funktionelle Einheit bilden, wobei die eigentliche Entwässerung der Faserstoffsuspension durch das erste Sieb hinweg erst auf der ersten Saugzone erfolgt und so zum Beispiel auch eine gegen der Sieblaufrichtung zurückströmende Faserstoffsuspension von dem vor der ersten Saugzone angeordneten Saugschuh abgesaugt werden kann. Somit wird Störungen bei der Blattbildung wirkungsvoll entgegengewirkt. In der ersten Saugzone kann der Aufbau einer Faserstoffmatte im initialen Bereich, also dem Bereich der Ablage von Fasern am ersten Sieb auf der ersten Saugzone mittels des konstant anliegenden, regel- und einstellbaren Vakuums die Entwässerung aktiv beeinflusst werden, wodurch die Bahnbildung positiv beeinflusst wird. Vor allem die Oberfläche der gebildeten Faserstoffbahn und der weitere Bahnaufbau werden durch die definierte Ablage der äußeren und der folgenden Faserstoffschicht mittels der oben beschriebenen Anordnung und Abfolge der Saugzonen sowie des regel- und einstellbaren Vakuums der jeweiligen Saugzone bzw. der Saugzonen besonders positiv beeinflusst.For the invention is therefore essential that the suction shoe and the subsequent suction zones of the dewatering box form a functional unit, wherein the actual dewatering of the pulp suspension through the first sieve takes place only on the first suction zone and so, for example, a against the Sieblaufrichtung back flowing pulp suspension can be sucked from the suction shoe arranged in front of the first suction zone. Thus, disturbances in sheet formation are effectively counteracted. In the first suction zone, the structure of a fibrous mat in the initial region, ie the area of deposition of fibers on the first sieve on the first suction zone by means of the constantly applied, adjustable and adjustable vacuum, the drainage can be actively influenced, whereby the web formation is positively influenced. Above all, the surface of the fibrous web formed and the further web structure are influenced particularly positively by the defined deposition of the outer and the following fibrous layers by means of the above-described arrangement and sequence of the suction zones and of the regulatable and adjustable vacuum of the respective suction zone or suction zones.

Letztendlich sind mit einem derartigen erfindungsgemäßen Verfahren Geschwindigkeiten von über 1.200 m/min, vorzugsweise von über 1.400 m/min, insbesondere von über 1.600 m/min, bei Herstellung von Faserstoffbahnen mit ausreichenden Qualitäten erreichbar, da sich keine Grenzschichten mehr vor den eigentlichen Entwässerungselementen aufbauen können.Ultimately, with such a method according to the invention, speeds of more than 1,200 m / min, preferably more than 1,400 m / min, in particular of more than 1,600 m / min, can be achieved in the production of fibrous webs with sufficient qualities, since no boundary layers build up before the actual dewatering elements can.

In einer ersten erfindungsgemäßen Ausführungsform ist vorgesehen, dass der in seiner Position einstellbare und an dem Entwässerungskasten unmittelbar angeordnete Saugschuh derart angeordnet wird, dass die eingebrachte und eine Schichthöhe aufweisende Faserstoffsuspension in der ersten Saugzone des Entwässerungskastens auf das erste Sieb aufläuft, von ihm also abgedeckt wird. Somit kann der Saugschuh das an ihm vorbei geführte erste Sieb ausreichend konditionieren, ohne hierbei die Grenzschicht der Faserstoffsuspension zu berühren.In a first embodiment according to the invention, it is provided that the suction shoe which can be adjusted in its position and is arranged directly on the drainage box is arranged in such a way that the fibrous suspension introduced and having a layer height accumulates on the first sieve in the first suction zone of the drainage box, ie is covered by it , Thus, the suction shoe can sufficiently condition the first screen guided past it without touching the boundary layer of the pulp suspension.

In einer weiteren erfindungsgemäßen Ausführungsform wird der in seiner Position einstellbare und an dem Entwässerungskasten unmittelbar angeordnete Saugschuh bevorzugt derart angeordnet, dass die eingebrachte und eine Schichthöhe aufweisende Faserstoffsuspension zu Beginn der ersten Saugzone des Entwässerungskastens auf das erste Sieb aufläuft, von ihm also abgedeckt wird. Dadurch wird die erste Saugzone von der Faserstoffsuspension und dem zweiten Sieb umschlungen und dermaßen komplett abgedichtet, dass die Höhe des sich ausbildenden Vakuums in der ersten Saugzone einstellbar und regelbar ist. Dies wirkt sich wiederum positiv auf die erreichbare Qualität der herzustellenden Faserstoffbahn aus.In a further embodiment according to the invention, the suction shoe, which can be adjusted in its position and is arranged directly on the drainage box, is preferably arranged such that the introduced pulp suspension having a layer height is at the beginning of the first suction zone of the dewatering box runs on the first sieve, so it is covered by him. As a result, the first suction zone is enveloped by the pulp suspension and the second wire and so completely sealed, that the height of the vacuum formed in the first suction zone is adjustable and adjustable. This in turn has a positive effect on the achievable quality of the fibrous web to be produced.

Ferner wird die Schichthöhe der Faserstoffsuspension in bevorzugter Weise unter Verwendung einer Gamma-Gauge-Messung oder eines elektrischen Messprinzips (kapazitiv oder induktiv) gemessen und das erhaltene Messsignal wird bevorzugt zur Steuerung/Regelung der zwischen den beiden Sieben ausgebildeten Spaltweite verwendet, wobei die Spaltweite der senkrechte Abstand des ersten Siebs an dem Ablaufpunkt von der Einlaufwalze von dem zweiten Sieb ist. Hierzu kann der mehrere Saugzonen umfassende Entwässerungskasten samt unmittelbar angeordnetem Saugschuh angehoben bzw. abgesenkt werden.Furthermore, the layer height of the pulp suspension is preferably measured using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) and the measurement signal obtained is preferably used to control the gap width formed between the two screens, wherein the gap width of the is the vertical distance of the first wire at the run-off point from the inlet roll of the second wire. For this purpose, the multiple suction zones comprehensive drainage box can be raised or lowered together with directly arranged suction shoe.

Im Hinblick auf die Erreichung von vielzähligen Betriebspositionen kann überdies vorgesehen sein, dass die das erste Sieb führende Einlaufwalze, der das erste Sieb von mitgeführten Substanzen entleerende und sowohl die entleerten Substanzen als auch die vom ersten Sieb mitgeführte Luft entfernende Saugschuh und der mehrere Saugzonen umfassende Entwässerungskasten unabhängig voneinander positioniert werden. Grundsätzlich können somit jegliche zur Erreichung guter Qualitäten notwendige Betriebsarten und -parameter eingestellt werden.Furthermore, with a view to attaining multiple operating positions, it is possible to provide the inlet sieve leading the first sieve, the suction shoe emptying the first sieve of entrained substances and removing both the emptied substances and the air entrained by the first sieve, and the multi-suction drainage box be positioned independently of each other. In principle, therefore, any operating modes and parameters necessary for achieving good qualities can be set.

Weiterhin kann es von Vorteil sein, wenn das zweite Sieb gegenseitig der ersten Saugzone des Entwässerungskastens über mehrere Leisten geführt wird, die mittels nachgiebiger Elemente abgestützt werden und die mit einer wählbaren Kraft gegen das zweite Sieb angedrückt werden. Somit werden schon frühzeitig weitere Impulse in die Faserstoffsuspension eingebracht, die die Entwässerung und Formation derselben merklich verbessern.Furthermore, it may be advantageous if the second sieve is guided mutually the first suction zone of the dewatering box over several bars, which are supported by means of resilient elements and which are pressed with a selectable force against the second sieve. Thus, further impulses are introduced early in the pulp suspension, which improve the drainage and formation of the same noticeably.

Auch kann das zweite Sieb gegenseitig aller Saugzonen des Entwässerungskastens über mehrere Leisten geführt werden, die mittels nachgiebiger Elemente abgestützt werden und die mit einer wählbaren Kraft gegen das zweite Sieb angedrückt werden. Die bereits angesprochenen Verbesserungen werden hierdurch nochmals verstärkt.Also, the second sieve can be guided mutually all suction zones of the dewatering box over several bars, which are supported by means of resilient elements and which are pressed with a selectable force against the second sieve. The above-mentioned improvements are thereby reinforced again.

Die erfindungsgemäße Aufgabe wird bei einem Doppelsiebformer der eingangs genannten Art dadurch gelöst, dass der wenigstens eine an dem Entwässerungskasten unmittelbar angeordnete Saugschuh in seiner Position einstellbar ausgebildet ist. Der Entwässerungskasten ist also zusammen mit dem Saugschuh als funktionelle Einheit ausgebildet und die mitgeführten Substanzen können beispielsweise Siebwasser oder dergleichen umfassen.The object of the invention is achieved in a twin-wire former of the type mentioned above in that the at least one suction shoe arranged directly on the drainage box is adjustable in its position. The drainage box is thus formed together with the suction shoe as a functional unit and the entrained substances may include, for example, white water or the like.

Die erfindungsgemäße Aufgabe wird hiermit wiederum vollständig gelöst und es ergeben sich die bereits angeführten Vorteile der Erfindung.The object of the invention is hereby in turn completely solved and there are the already mentioned advantages of the invention.

Weitere Merkmale und Vorteile der Erfindung ergeben sich aus den weiteren abhängigen Vorrichtungsansprüchen.Further features and advantages of the invention will become apparent from the other dependent device claims.

So ist es insbesondere vorteilhaft, wenn der Saugschuh eine offene Saugfläche im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, aufweist. Diese Bereiche gewährleisten eine ausreichende Besaugung sowohl des ersten Siebs als auch des freien Einlaufspalts.Thus, it is particularly advantageous if the suction shoe has an open suction surface in the range of 10 to 90%, preferably from 30 to 49%. These areas ensure adequate suction of both the first sieve and the free inlet gap.

Dabei kann der Saugschuh bevorzugt wenigstens einen Saugbelag aufweisen, der zumindest einen geschlitzten Belag oder mehrere verschiebbare Leisten umfasst. Die einzelnen Leisten können dabei auf einem konvex gekrümmten Saugkasten montiert sein, wobei die Leistenabstände frei wählbar sind und unterschiedliche Schlitzbreiten eingestellt werden können.In this case, the suction shoe may preferably have at least one suction pad which has at least one slotted covering or a plurality of slidable strips includes. The individual strips can be mounted on a convexly curved suction box, the strip distances are freely selectable and different slot widths can be adjusted.

Ferner weist der Saugschuh bevorzugt einen konvexen Krümmungsradius im Bereich von 300 bis 6.000 mm, vorzugsweise von 800 bis 3.000 mm, auf. Dieser konvexe Krümmungsradius fördert einen stabilen Sieblauf, gewährleistet definierte Einlaufbedingungen und stellt eine gute Siebzusammenführung sicher. Überdie gibt der konvexe Krümmungsradius den konvergierenden Einlaufspalt vor, mit dem Ziel einer sanfteren Entwässerung der Faserstoffsuspension. Auch erfährt die auf dem zweiten Sieb befindliche Faserstoffsuspension definierte Auftreffbedingungen auf das erste Sieb.Furthermore, the suction shoe preferably has a convex radius of curvature in the range from 300 to 6,000 mm, preferably from 800 to 3,000 mm. This convex radius of curvature promotes a stable sifting run, ensures defined run-in conditions and ensures a good sieve consolidation. The convex radius of curvature predetermines the converging inlet gap with the aim of softer dewatering of the pulp suspension. Also, the pulp suspension located on the second wire undergoes defined impact conditions on the first wire.

Weiterhin weist die erste Saugzone des Entwässerungskastens eine offene Saugfläche im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und/oder eine einen konvexen Krümmungsradius im Bereich von 300 bis 10.000 mm, vorzugsweise von 800 bis 6.000 mm, auf. Die genannte offene Saugfläche ist ausreichend, um das erste Sieb auf der verbleibenden Fläche noch sicher zu führen und entsprechend auch zu stützen. Überdies können noch eine optimale Besaugung und Wasserabfuhr sichergestellt werden.Furthermore, the first suction zone of the dewatering box has an open suction area in the range from 10 to 90%, preferably from 30 to 49%, and / or a convex radius of curvature in the range from 300 to 10,000 mm, preferably from 800 to 6,000 mm. Said open suction surface is sufficient to guide the first wire on the remaining surface still safe and to support accordingly. In addition, optimal suction and drainage can be ensured.

Der erfindungsgemäße Doppelsiebformer kann in einer ersten praktischen Ausführungsform prinzipiell als ein an sich bekannter Hybridformer ausgebildet sein, wobei das zweite, die eingebrachte Faserstoffsuspension aufnehmende Sieb bevorzugt ein Fourdriniersieb ist, welches vor Einlauf in die Doppelsiebzone über eine Vorentwässerungszone geführt ist.In a first practical embodiment, the twin-wire former according to the invention can in principle be designed as a hybrid former known per se, wherein the second sieve receiving the introduced pulp suspension is preferably a Fourdrinier wire, which is guided over a pre-dewatering zone prior to entry into the twin-wire zone.

In einer zweiten praktischen Ausführungsform kann der erfindungsgemäße Doppelsiebformer als ein an sich bekannter Spaltformer ausgebildet sein, wobei die das erste Sieb führende Einlaufwalze bevorzugt eine Brustwalze ist und wobei die Doppelsiebzone bevorzugt im Wesentlichen horizontal oder annähernd horizontal, unter einem Steigungswinkel zur Horizontalen oder vertikal oder annähernd vertikal verläuft.In a second practical embodiment, the twin-wire former according to the invention may be formed as a gap former known per se, wherein the inlet roller leading the first screen is preferably a breast roller and wherein the twin-wire zone preferably substantially horizontal or approximately horizontally, at a pitch angle to the horizontal, or vertical or approximately vertical.

Weitere Merkmale und Vorteile der Erfindung ergeben sich aus der nachfolgenden Beschreibung bevorzugter Ausführungsbeispiele unter Bezugnahme auf die Zeichnung.Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

Es zeigen

Figur 1
eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone einer ersten Ausführungsform eines erfindungsgemäßen Doppelsiebformers;
Figur 2
eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone einer zweiten Ausführungsform eines erfindungsgemäßen Doppelsiebformers; und
Figur 3
eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone einer dritten Ausführungsform eines erfindungsgemäßen Doppelsiebformers.
Show it
FIG. 1
a schematic and sectional side view of an initial portion of a twin-wire zone of a first embodiment of a twin-wire former according to the invention;
FIG. 2
a schematic and sectional side view of an initial portion of a twin-wire zone of a second embodiment of a twin-wire former according to the invention; and
FIG. 3
a schematic and sectional side view of an initial portion of a twin-wire zone of a third embodiment of a Doppelsiebformers invention.

Die Figur 1 zeigt eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone 2 eines als Hybridformer ausgeführten Doppelsiebformers 1. Die Doppelsiebzone 2 verläuft im Wesentlichen horizontal oder annähernd horizontal.The FIG. 1 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a hybrid former. The twin-wire zone 2 extends essentially horizontally or approximately horizontally.

Der Doppelsiebformer 1 ist Teil einer nicht weiters dargestellten Maschine zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension 3.The twin-wire former 1 is part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.

Der Doppelsiebformer 1 umfasst zwei umlaufende endlose Siebe, ein erstes Sieb 4, welches auch als Obersieb bezeichnet wird, und ein zweites Sieb 5, welches auch als Fourdriniersieb, Untersieb oder Tragsieb bezeichnet wird. Die Siebe 4, 5 bilden zumindest streckenweise miteinander die Doppelsiebzone 2, die einen keilförmigen Einlaufspalt 6 für die Faserstoffsuspension 3 aufweist.The twin-wire former 1 comprises two continuous endless sieves, a first sieve 4, which is also referred to as an upper sieve, and a second sieve 5, which is also referred to as a Fourdrinier sieve, lower sieve or carrier sieve. The sieves 4, 5 form at least in sections with each other, the twin-wire zone 2, which has a wedge-shaped inlet gap 6 for the pulp suspension 3.

Die nicht dargestellte Einbringung der Faserstoffsuspension 3 auf das zweite Sieb 5 erfolgt mittels mindestens eines bekannten, jedoch nicht explizit dargestellten Stoffauflaufs 7, dessen Stoffauflaufdüse 8 überdies mit mindestens einer Lamelle 9 zwecks Beeinflussung und Verbesserung der Strahlqualität versehen sein kann (vgl. Figuren 2 und 3).The introduction, not shown, of the pulp suspension 3 onto the second wire 5 takes place by means of at least one known but not explicitly illustrated head box 7, whose headbox nozzle 8 can moreover be provided with at least one lamella 9 for the purpose of influencing and improving the beam quality (cf. FIGS. 2 and 3 ).

Das erste Sieb 4 ist über eine vorzugsweise positionierbare Einlaufwalze 10 geführt, deren mögliche Positionierbarkeit mittels eines symbolischen Bewegungsdoppelpfeils A angedeutet ist. Anschließend ist das erste Sieb 4 in der Doppelsiebzone 2 über mehrere mit gegenseitigem Abstand starr an einem vorzugsweise positionierbaren und mehrere Saugzonen Z11.x umfassenden Entwässerungskasten 11 angeordnete Leisten 12 geführt. Die Positionierbarkeit des Entwässerungskastens 11 ist mittels eines symbolischen Bewegungsdoppelpfeils B angedeutet. Der Entwässerungskasten 11 weist insgesamt drei Saugzonen Z11.1, Z11.2 und Z11.3 auf, die unmittelbar hintereinander angeordnet sind und die mit unterschiedlichen Unterdrücken pU11.1, pU11.2 und pU11.3 beaufschlagbar sind. Die Einheiten zur Erzeugung der jeweiligen Unterdrücke pU11.1, pU11.2 und pU11.3 sind, da sie dem Fachmann mehr als bekannt sind, nicht explizit dargestellt. Das erste Sieb 4 deckt während seines Laufs des ersten Siebs 4 von der Einlaufwalze 10 zu dem Entwässerungskasten 11 die bereits auf das zweite Sieb 5 eingebrachte Faserstoffsuspension 3 ab.The first screen 4 is guided over a preferably positionable inlet roller 10, whose possible positioning is indicated by means of a symbolic motion double arrow A. Subsequently, the first sieve 4 in the twin-wire zone 2 is guided over a plurality of strips 12, which are arranged rigidly at a mutual distance on a preferably positionable and several suction zones Z11.x comprehensive drainage box 11. The positionability of the dewatering box 11 is indicated by means of a symbolic movement double arrow B. The drainage box 11 has a total of three suction zones Z11.1, Z11.2 and Z11.3, which are arranged directly one behind the other and which can be acted upon by different suppressions pU11.1, pU11.2 and pU11.3. The units for generating the respective negative pressures pU11.1, pU11.2 and pU11.3, since they are more than known to the person skilled in the art, are not explicitly shown. The first wire 4 covers during its course of the first sieve 4 from the inlet roller 10 to the dewatering box 11 from the already introduced on the second sieve 5 pulp suspension 3 from.

Das zweite und die eingebrachte Faserstoffsuspension 3 aufnehmende Sieb 5 ist in der Doppelsiebzone 2 über mehrere Leisten 13 geführt, die mittels nachgiebiger Elemente 14 abgestützt sind und die mit einer wählbaren Kraft F13 (Pfeil) gegen das zweite Sieb 2 angedrückt sind. Die Leisten 13 sind gegenseitig der Leisten 12 der zweiten Saugzonen Z11.2 des Entwässerungskastens 11 angeordnet. Das zweite Sieb 5 ist ein Fourdriniersieb 5.1, welches vor Einlauf in die Doppelsiebzone 2 über eine lediglich angedeutete, dem Fachmann jedoch bekannte Vorentwässerungszone 15 geführt ist.The second and the introduced pulp suspension 3 receiving sieve 5 is guided in the twin-wire zone 2 over a plurality of strips 13 which are supported by resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2. The strips 13 are mutually arranged on the strips 12 of the second suction zones Z11.2 of the drainage box 11. The second sieve 5 is a Fourdriniersieb 5.1, which before entering the Twin-wire zone 2 is guided over a merely indicated, but known to those skilled pre-dewatering zone 15.

Ferner ist das erste, die eingebrachte Faserstoffsuspension 3 noch nicht abdeckende Sieb 4 unmittelbar vor seiner Führung über die starr an dem Entwässerungskasten 11 angeordneten Leisten 12 durch den Wirkbereich W wenigstens eines an dem Entwässerungskasten 11 vorzugsweise in seiner Position einstellbar angeordneten Saugschuhs 16 geführt, welcher infolge der vorzugsweise steuer-/regelbaren Besaugung des Wirkbereichs W mit einem Unterdruck pU16 das erste Sieb 4 von mitgeführten Substanzen entleert und sowohl die entleerten Substanzen als auch die vom ersten Sieb 4 mitgeführte Luft entfernt. Die vorzugsweise steuer-/regelbare Besaugung mit dem Unterdruck pU16 ist mittels eines Pfeils C angedeutet.Furthermore, the first, the introduced pulp suspension 3 is not yet covered sieve 4 immediately before its leadership on the rigidly arranged on the drainage box 11 strips 12 by the effective range W at least one of the drainage box 11 preferably in its position adjustably arranged suction shoe 16, which due the preferably controllable / controllable aspiration of the effective range W with a negative pressure pU16 empties the first sieve 4 of entrained substances and removes both the deflated substances and the entrained air from the first sieve 4. The preferably controllable / suction with the vacuum pU16 is indicated by an arrow C.

Der Saugschuh 16 ist also nicht starr an dem Entwässerungskasten 11 angeordnet, er ist vielmehr in seiner allgemeinen Position, insbesondere auch im Bezug auf den Entwässerungskasten 11 vorzugsweise frei einstellbar. Die Positionierbarkeit des Saugschuhs 16 ist mittels eines Bewegungsdoppelpfeils D angedeutet. Selbstverständlich kann er auch zusammen mit dem Entwässerungskasten 11 aufgrund einer zumindest zeitweisen Kopplung gemeinsam positioniert werden.The suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11. The positionability of the suction shoe 16 is indicated by means of a movement double arrow D. Of course, it can also be positioned together with the drainage box 11 due to an at least temporary coupling together.

Im Wirkbereich W des Saugschuhs 16 muss das erste Sieb 4 nicht vollständig an ihm anliegen, es kann vielmehr auch nur streckenweise, das heißt ablaufseitig über ihn geführt sein, sofern es nicht direkt auf die erste Saugzone pU11.1 des Entwässerungskastens 11 aufläuft.In the effective region W of the suction shoe 16, the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.

Zudem ist der Saugschuh 16 nach Möglichkeit dichtend zu der Einlaufwalze 10 angeordnet, so dass lediglich die in den Einlaufspalt 6 eingebrachte Luft und nicht die Umgebungsluft hinter dem Saugschuh angesaugt und entfernt wird. Die Dichtung kann aufgrund einer ensprechenden geometrischen Ausbildung der beiden Bauteile 10, 16, aber auch aufgrund zusätzlicher Einbauten, wie beispielsweise Dichtelemente und dergleichen, bewirkt werden.In addition, if possible, the suction shoe 16 is arranged sealingly with respect to the inlet roller 10, so that only the air introduced into the inlet gap 6 and not the ambient air is sucked in and removed behind the suction shoe. The seal can due to a ensprechenden geometric design of the Both components 10, 16, but also due to additional fittings, such as sealing elements and the like, can be effected.

Weiterhin weist der Saugschuh 16 eine offene Saugfläche F16 im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und einen konvexen Krümmungsradius K16 im Bereich von 300 bis 6.000 mm, vorzugsweise von 800 bis 3.000 mm, auf. Der Saugschuh 16 weist hierzu wenigstens einen Saugbelag 17 auf, der zumindest einen geschlitzten Belag oder mehrere verschiebbare Leisten umfasst. Der Saugbelag 17 ist lediglich gestrichelt angedeutet.Furthermore, the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm. For this purpose, the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips. The suction pad 17 is indicated only by dashed lines.

Gemäß der Darstellung in der Figur 1 ist der in seiner Position einstellbare und an dem Entwässerungskasten 11 unmittelbar angeordnete Saugschuh 16 derart angeordnet, dass die eingebrachte und eine Schichthöhe H3 aufweisende Faserstoffsuspension 3 an einem Auftreffpunkt ATP in der ersten Saugzone Z11.1 des Entwässerungskastens 11 auf das erste Sieb 4 aufläuft, von ihm also abgedeckt ist.As shown in the FIG. 1 the suction shoe 16, which can be adjusted in its position and is arranged directly on the dewatering box 11, is arranged in such a way that the fibrous suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP in the first suction zone Z11.1 of the dewatering box 11 So it is covered.

In alternativer und nicht explizit dargestellter Ausführung kann der in seiner Position einstellbare und an dem Entwässerungskasten 11 unmittelbar angeordnete Saugschuh 16 auch derart angeordnet sein, dass die eingebrachte und eine Schichthöhe H3 aufweisende Faserstoffsuspension 3 an einem Auftreffpunkt ATP zu Beginn der ersten Saugzone Z11.1 des Entwässerungskastens 11 auf das erste Sieb 4 aufläuft, von ihm also abgedeckt ist.In an alternative embodiment, which is not explicitly shown, the suction shoe 16, which can be adjusted in position and is arranged directly on the drainage box 11, can also be arranged in such a way that the fibrous suspension 3 having a layer height H3 has an impact point ATP at the beginning of the first suction zone Z11.1 of FIG Drainage box 11 runs onto the first sieve 4, so it is covered by him.

Bei beiden soeben beschriebenen Ausführungen ist eine lediglich angedeutete Einrichtung 18 zur Messung der Schichthöhe H3 der Faserstoffsuspension 3 unter Verwendung einer Gamma-Gauge-Messung oder eines elektrischen Messprinzips (kapazitiv oder induktiv) vorgesehen, wobei das erhaltene Messsignal zur Steuerung/Regelung der zwischen den beiden Sieben ausgebildeten Spaltweite S verwendet wird. Die Spaltweite S ist hierbei per Definition der senkrechte Abstand des ersten Siebs 4 an dem Ablaufpunkt P von der Einlaufwalze 10 von dem zweiten Sieb 5. Die Spaltweite S kann dadurch eingestellt werden, dass die das erste Sieb 4 führende Einlaufwalze 10, der das erste Sieb 4 von mitgeführten Substanzen entleerende und sowohl die entleerten Substanzen als auch die vom ersten Sieb 3 mitgeführte Luft entfernende Saugschuh 16 und der mehrere Saugzonen Z11.x umfassende Entwässerungskasten 11 unabhängig voneinander positionierbar sind (Bewegungsdoppelpfeile A, B und D).In both embodiments just described, a merely indicated device 18 for measuring the layer height H3 of the pulp suspension 3 using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) is provided, wherein the measurement signal obtained for controlling / regulating the between the two Seven trained gap width S is used. The gap width S is here by definition the vertical distance of the first sieve 4 at the drain point P of the inlet roll 10 from the second sieve 5. The gap width S can be adjusted by the inlet sieve 10 leading the first sieve 4 emptying the first sieve 4 of entrained substances and both the emptied substances and the air entrained by the first sieve 3 removing suction shoe 16 and the plurality of suction zones Z11.x comprehensive drainage box 11 are independently positionable (double movement arrows A, B and D).

Die erste Saugzone Z11.1 des Entwässerungskastens 11 weist überdies eine offene Saugfläche F11.1 im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und einen konvexen Krümmungsradius K11.1 im Bereich von 300 bis 10.000 mm, vorzugsweise von 800 bis 6.000 mm, auf.The first suction zone Z11.1 of the dewatering box 11 also has an open suction surface F11.1 in the range of 10 to 90%, preferably 30 to 49%, and a convex radius of curvature K11.1 in the range of 300 to 10,000 mm, preferably 800 up to 6,000 mm, on.

Die Figur 2 zeigt eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone 2 eines als Spaltformer ausgeführten Doppelsiebformers 1. Die Doppelsiebzone 2 verläuft im Wesentlichen vertikal oder annähernd vertikal. Sie kann in weiterer Ausgestaltung auch unter einem Steigungswinkel zur Horizontalen verlaufen.The FIG. 2 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a gap former. The twin-wire zone 2 extends substantially vertically or approximately vertically. It can also extend in a further embodiment at a pitch angle to the horizontal.

Auch dieser Doppelsiebformer 1 ist Teil einer nicht weiters dargestellten Maschine zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension 3.This twin-wire former 1 is also part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.

Der Doppelsiebformer 1 umfasst zwei umlaufende endlose Siebe, ein erstes Sieb 4, welches auch als Obersieb bezeichnet wird, und ein zweites Sieb 5, welches auch als Untersieb oder Tragsieb bezeichnet wird. Die Siebe 4, 5 bilden zumindest streckenweise miteinander die Doppelsiebzone 2, die einen keilförmigen Einlaufspalt 6 für die Faserstoffsuspension 3 aufweist.The twin-wire former 1 comprises two continuous endless sieves, a first sieve 4, which is also referred to as a top sieve, and a second sieve 5, which is also referred to as a bottom sieve or a support sieve. The sieves 4, 5 form at least in sections with each other the twin-wire zone 2, which has a wedge-shaped inlet gap 6 for the pulp suspension 3.

Die Einbringung der Faserstoffsuspension 3 auf das zweite Sieb 5 erfolgt mittels mindestens eines bekannten Stoffauflaufs 7, dessen Stoffauflaufdüse 8 überdies mit mindestens einer Lamelle 9 zwecks Beeinflussung und Verbesserung der Strahlqualität versehen sein kann.The introduction of the pulp suspension 3 to the second wire 5 by means of at least one known headbox 7, the headbox 8 also can be provided with at least one blade 9 for influencing and improving the beam quality.

Das erste Sieb 4 ist über eine vorzugsweise positionierbare Einlaufwalze 10 in Ausgestaltung einer Brustwalze geführt, deren mögliche Positionierbarkeit mittels eines symbolischen Bewegungsdoppelpfeils A angedeutet ist. Anschließend ist das erste Sieb 4 in der Doppelsiebzone 2 über mehrere mit gegenseitigem Abstand starr an einem vorzugsweise positionierbaren und mehrere Saugzonen Z11.x umfassenden Entwässerungskasten 11 angeordnete Leisten 12 geführt. Die Positionierbarkeit des Entwässerungskastens 11 ist mittels eines symbolischen Bewegungsdoppelpfeils B angedeutet. Der Entwässerungskasten 11 weist insgesamt drei Saugzonen Z11.1, Z11.2 und Z11.3 auf, die unmittelbar hintereinander angeordnet sind und die mit unterschiedlichen Unterdrücken pU11.1, pU11.2 und pU11.3 beaufschlagbar sind. Die Einheiten zur Erzeugung der jeweiligen Unterdrücke pU11.1, pU11.2 und pU11.3 sind, da sie dem Fachmann mehr als bekannt sind, nicht explizit dargestellt. Das erste Sieb 4 deckt während seines Laufs des ersten Siebs 4 von der Einlaufwalze 10 zu dem Entwässerungskasten 11 die bereits auf das zweite Sieb 5 eingebrachte Faserstoffsuspension 3 ab.The first sieve 4 is guided over a preferably positionable inlet roller 10 in the form of a breast roller whose possible positioning capability is indicated by means of a symbolic movement double arrow A. Subsequently, the first sieve 4 in the twin-wire zone 2 is guided over a plurality of strips 12, which are arranged rigidly at a mutual distance on a preferably positionable and several suction zones Z11.x comprehensive drainage box 11. The positionability of the dewatering box 11 is indicated by means of a symbolic movement double arrow B. The drainage box 11 has a total of three suction zones Z11.1, Z11.2 and Z11.3, which are arranged directly one behind the other and which can be acted upon by different suppressions pU11.1, pU11.2 and pU11.3. The units for generating the respective negative pressures pU11.1, pU11.2 and pU11.3, since they are more than known to the person skilled in the art, are not explicitly shown. The first wire 4 covers during its course of the first sieve 4 from the inlet roller 10 to the dewatering box 11 from the already introduced on the second sieve 5 pulp suspension 3 from.

Das zweite und die eingebrachte Faserstoffsuspension 3 aufnehmende Sieb 5 ist in der Doppelsiebzone 2 über mehrere Leisten 13 geführt, die mittels nachgiebiger Elemente 14 abgestützt sind und die mit einer wählbaren Kraft F13 (Pfeil) gegen das zweite Sieb 2 angedrückt sind. Die Leisten 13 sind zumindest gegenseitig der Leisten 12 der zwei Saugzonen Z11.1 und Z11.2 des Entwässerungskastens 11 angeordnet. Erweiternd können die Leisten 13 zudem auch gegenseitig der Leisten 12 der dritten Saugzone Z11.3 des Entwässerungskastens 11 angeordnet sein (gestrichelte Darstellung).The second and the introduced pulp suspension 3 receiving sieve 5 is guided in the twin-wire zone 2 over a plurality of strips 13 which are supported by resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2. The strips 13 are arranged at least mutually the strips 12 of the two suction zones Z11.1 and Z11.2 of the drainage box 11. Expanding the strips 13 may also be mutually the strips 12 of the third suction Z11.3 the drainage box 11 arranged (dashed line).

Ferner ist das erste, die eingebrachte Faserstoffsuspension 3 noch nicht abdeckende Sieb 4 unmittelbar vor seiner Führung über die starr an dem Entwässerungskasten 11 angeordneten Leisten 12 durch den Wirkbereich W wenigstens eines an dem Entwässerungskasten 11 vorzugsweise in seiner Position einstellbar angeordneten Saugschuhs 16 geführt, welcher infolge der vorzugsweise steuer-/regelbaren Besaugung des Wirkbereichs W mit einem Unterdruck pU16 das erste Sieb 4 von mitgeführten Substanzen entleert und sowohl die entleerten Substanzen als auch die vom ersten Sieb 4 mitgeführte Luft entfernt. Die vorzugsweise steuer-/regelbare Besaugung ist mittels eines Pfeils C angedeutet.Furthermore, the first, the introduced pulp suspension 3 not yet covering sieve 4 immediately before his leadership on the rigidly arranged on the drainage box 11 strips 12 through the effective range W. at least one of the drainage box 11 preferably in its position adjustably arranged suction shoe 16 which emptied due to the preferably controllable / controllable suction of the effective range W with a negative pressure pU16 the first sieve 4 of entrained substances and both the emptied substances and those of the first Sieve 4 entrained air removed. The preferably controllable / suction is indicated by means of an arrow C.

Der Saugschuh 16 ist also nicht starr an dem Entwässerungskasten 11 angeordnet, er ist vielmehr in seiner allgemeinen Position, insbesondere auch im Bezug auf den Entwässerungskasten 11 vorzugsweise frei einstellbar. Die Positionierbarkeit des Saugschuhs 16 ist mittels eines Bewegungsdoppelpfeils D angedeutet.The suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11. The positionability of the suction shoe 16 is indicated by means of a movement double arrow D.

Im Wirkbereich W des Saugschuhs 16 muss das erste Sieb 4 nicht vollständig an ihm anliegen, es kann vielmehr auch nur streckenweise, das heißt ablaufseitig über ihn geführt sein, sofern es nicht direkt auf die erste Saugzone pU11.1 des Entwässerungskastens 11 aufläuft.In the effective region W of the suction shoe 16, the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.

Zudem ist der Saugschuh 16 nach Möglichkeit dichtend zu der Einlaufwalze 10 angeordnet, so dass lediglich die in den Einlaufspalt 6 eingebrachte Luft und nicht die Umgebungsluft hinter dem Saugschuh angesaugt und entfernt wird. Die Dichtung kann aufgrund einer ensprechenden geometrischen Ausbildung der beiden Bauteile 10, 16, aber auch aufgrund zusätzlicher Einbauten, wie beispielsweise Dichtelemente und dergleichen, bewirkt werden.In addition, if possible, the suction shoe 16 is arranged sealingly with respect to the inlet roller 10, so that only the air introduced into the inlet gap 6 and not the ambient air is sucked in and removed behind the suction shoe. The seal can be effected due to a ensprechenden geometric design of the two components 10, 16, but also due to additional fittings, such as sealing elements and the like.

Weiterhin weist der Saugschuh 16 eine offene Saugfläche F16 im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und einen konvexen Krümmungsradius K16 im Bereich von 300 bis 6.000 mm, vorzugsweise von 800 bis 3.000 mm, auf. Der Saugschuh 16 weist hierzu wenigstens einen Saugbelag 17 auf, der zumindest einen geschlitzten Belag oder mehrere verschiebbare Leisten umfasst. Der Saugbelag 17 ist lediglich gestrichelt angedeutet.Furthermore, the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm. For this purpose, the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips. The suction pad 17 is indicated only by dashed lines.

Gemäß der Darstellung in der Figur 2 ist der in seiner Position einstellbare und an dem Entwässerungskasten 11 unmittelbar angeordnete Saugschuh 16 derart angeordnet, dass die eingebrachte und eine Schichthöhe H3 aufweisende Faserstoffsuspension 3 an einem Auftreffpunkt ATP zu Beginn der ersten Saugzone Z11.1 des Entwässerungskastens 11 auf das erste Sieb 4 aufläuft, von ihm also abgedeckt ist.As shown in the FIG. 2 the suction shoe 16, which can be adjusted in position and is arranged directly on the drainage box 11, is arranged such that the fibrous stock suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP at the beginning of the first suction zone Z11.1 of the drainage box 11, is covered by him so.

In alternativer und nicht explizit dargestellter Ausführung kann der in seiner Position einstellbare und an dem Entwässerungskasten 11 unmittelbar angeordnete Saugschuh 16 auch derart angeordnet sein, dass die eingebrachte und eine Schichthöhe H3 aufweisende Faserstoffsuspension 3 an einem Auftreffpunkt ATP in der ersten Saugzone Z11.1 des Entwässerungskastens 11 auf das erste Sieb 4 aufläuft, von ihm also abgedeckt ist.In an alternative embodiment, which is not explicitly shown, the suction shoe 16, which can be adjusted in position and disposed directly on the drainage box 11, can also be arranged such that the introduced pulp suspension 3 having a layer height H3 at an impact point ATP in the first suction zone Z11.1 of the drainage box 11 accumulates on the first sieve 4, so it is covered by him.

Bei beiden soeben beschriebenen Ausführungen ist eine lediglich angedeutete Einrichtung 18 zur Messung der Schichthöhe H3 der Faserstoffsuspension 3 unter Verwendung einer Gamma-Gauge-Messung oder eines elektrischen Messprinzips (kapazitiv oder induktiv) vorgesehen, wobei das erhaltene Messsignal zur Steuerung/Regelung der zwischen den beiden Sieben ausgebildeten Spaltweite S verwendet wird. Die Spaltweite S ist hierbei per Definition der senkrechte Abstand des ersten Siebs 4 an dem Ablaufpunkt P von der Einlaufwalze 10 von dem zweiten Sieb 5. Die Spaltweite S kann dadurch eingestellt werden, dass die das erste Sieb 4 führende Einlaufwalze 10, der das erste Sieb 4 von mitgeführten Substanzen entleerende und sowohl die entleerten Substanzen als auch die vom ersten Sieb 3 mitgeführte Luft entfernende Saugschuh 16 und der mehrere Saugzonen Z11.x umfassende Entwässerungskasten 11 unabhängig voneinander positionierbar sind (Bewegungsdoppelpfeile A, B und D).In both embodiments just described, a merely indicated device 18 for measuring the layer height H3 of the pulp suspension 3 using a gamma-gauge measurement or an electrical measuring principle (capacitive or inductive) is provided, wherein the measurement signal obtained for controlling / regulating the between the two Seven trained gap width S is used. The gap width S is here by definition the vertical distance of the first sieve 4 at the drain point P of the inlet roll 10 of the second sieve 5. The gap width S can be adjusted so that the first sieve 4 leading inlet roll 10, which is the first sieve 4 emptying of entrained substances and both the deflated substances and the air entrained by the first screen 3 removing suction shoe 16 and the plurality of suction zones Z11.x comprehensive drainage box 11 are independently positionable (double movement arrows A, B and D).

Die erste Saugzone Z11.1 des Entwässerungskastens 11 weist überdies eine offene Saugfläche F11.1 im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und einen konvexen Krümmungsradius K11.1 im Bereich von 300 bis 10.000 mm, vorzugsweise von 800 bis 6.000 mm, auf.The first suction zone Z11.1 of the dewatering box 11 also has an open suction surface F11.1 in the range of 10 to 90%, preferably 30 to 49 %, and a convex curvature radius K11.1 in the range of 300 to 10,000 mm, preferably 800 to 6,000 mm.

Die Figur 3 zeigt eine schematische und geschnittene Seitenansicht eines Anfangsbereichs einer Doppelsiebzone 2 eines als Spaltformer ausgeführten Doppelsiebformers 1. Die Doppelsiebzone 2 verläuft im Wesentlichen vertikal oder annähernd vertikal. Sie kann in weiterer Ausgestaltung auch unter einem Steigungswinkel zur Horizontalen verlaufen.The FIG. 3 shows a schematic and sectional side view of an initial portion of a twin-wire zone 2 of a twin-wire former 1 designed as a gap former. The twin-wire zone 2 extends substantially vertically or approximately vertically. It can also extend in a further embodiment at a pitch angle to the horizontal.

Auch dieser Doppelsiebformer 1 ist Teil einer nicht weiters dargestellten Maschine zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension 3.This twin-wire former 1 is also part of a machine not shown further for producing a fibrous web, in particular a paper or board web, from at least one fibrous stock suspension 3.

Der dargestellte Doppelsiebformer 1 entspricht im Wesentlichen dem in der Figur 2 dargestellten Doppelsiebformer 1, so dass hiermit hinsichtlich seiner Beschreibung auf die Beschreibung des in der Figur 2 dargestellten Doppelsiebformers 1 verwiesen wird.The illustrated twin-wire former 1 essentially corresponds to that in FIG FIG. 2 shown twin-wire former 1, so that hereby with regard to its description to the description of the in the FIG. 2 shown twin-wire former 1 is referenced.

Das zweite und die eingebrachte Faserstoffsuspension 3 aufnehmende Sieb 5 des Doppelsiebformers 1 der Figur 3 ist in der Doppelsiebzone 2 über mehrere Leisten 13 geführt, die mittels nachgiebiger Elemente 14 abgestützt sind und die mit einer wählbaren Kraft F13 (Pfeil) gegen das zweite Sieb 2 angedrückt sind. Die Leisten 13 sind gegenseitig der Leisten 12 der zweiten Saugzonen Z11.2 des Entwässerungskastens 11 angeordnet.The second and the introduced pulp suspension 3 receiving sieve 5 of the twin-wire former 1 of FIG. 3 is guided in the twin-wire zone 2 over a plurality of strips 13, which are supported by means of resilient elements 14 and which are pressed with a selectable force F13 (arrow) against the second wire 2. The strips 13 are mutually arranged on the strips 12 of the second suction zones Z11.2 of the drainage box 11.

Im Anschluss an den Entwässerungskasten ist gegenseitig ein dem Fachmann bekanntes Entwässerungselement 19 angeordnet, welches durch das zweite Sieb 5 hindurch die Faserstoffsuspension 3 beaufschlagt.Following the dewatering box, a dewatering element 19 known to the person skilled in the art is arranged, which acts on the pulp suspension 3 through the second wire 5.

Wiederum ist das erste, die eingebrachte Faserstoffsuspension 3 noch nicht abdeckende Sieb 4 unmittelbar vor seiner Führung über die starr an dem Entwässerungskasten 11 angeordneten Leisten 12 durch den Wirkbereich W wenigstens eines an dem Entwässerungskasten 11 vorzugsweise in seiner Position einstellbar angeordneten Saugschuhs 16 geführt, welcher infolge der vorzugsweise steuer-/regelbaren Besaugung des Wirkbereichs W mit einem Unterdruck pU16 das erste Sieb 4 von mitgeführten Substanzen entleert und sowohl die entleerten Substanzen als auch die vom ersten Sieb 4 mitgeführte Luft entfernt. Die vorzugsweise steuer-/regelbare Besaugung ist mittels eines Pfeils C angedeutet.Again, the first, the introduced pulp suspension 3 not yet covering sieve 4 immediately before its leadership on the rigidly arranged on the drainage box 11 strips 12 by the effective range W at least one of the drainage box 11 preferably in its position adjustably arranged suction shoe 16 which emptied due to the preferably controllable / controllable suction of the effective range W with a negative pressure pU16 the first sieve 4 of entrained substances and both the emptied substances and those of the first Sieve 4 entrained air removed. The preferably controllable / suction is indicated by means of an arrow C.

Der Saugschuh 16 ist also nicht starr an dem Entwässerungskasten 11 angeordnet, er ist vielmehr in seiner allgemeinen Position, insbesondere auch im Bezug auf den Entwässerungskasten 11 vorzugsweise frei einstellbar. Die Positionierbarkeit des Saugschuhs 16 ist mittels eines Bewegungsdoppelpfeils D angedeutet.The suction shoe 16 is therefore not rigidly disposed on the drainage box 11, but it is preferably freely adjustable in its general position, in particular also with respect to the drainage box 11. The positionability of the suction shoe 16 is indicated by means of a movement double arrow D.

Im Wirkbereich W des Saugschuhs 16 muss das erste Sieb 4 nicht vollständig an ihm anliegen, es kann vielmehr auch nur streckenweise, das heißt ablaufseitig über ihn geführt sein, sofern es nicht direkt auf die erste Saugzone pU11.1 des Entwässerungskastens 11 aufläuft.In the effective region W of the suction shoe 16, the first sieve 4 does not have to abut it completely, but rather it can only be guided over it in sections, that is, on the outlet side, unless it runs directly onto the first suction zone pU11.1 of the dewatering box 11.

Weiterhin weist der Saugschuh 16 eine offene Saugfläche F16 im Bereich von 10 bis 90 %, vorzugsweise von 30 bis 49 %, und einen konvexen Krümmungsradius K16 im Bereich von 300 bis 6.000 mm, vorzugsweise von 800 bis 3.000 mm, auf. Der Saugschuh 16 weist hierzu wenigstens einen Saugbelag 17 auf, der zumindest einen geschlitzten Belag oder mehrere verschiebbare Leisten umfasst. Der Saugbelag 17 ist lediglich gestrichelt angedeutet.Furthermore, the suction shoe 16 has an open suction surface F16 in the range of 10 to 90%, preferably 30 to 49%, and a convex curvature radius K16 in the range of 300 to 6,000 mm, preferably from 800 to 3,000 mm. For this purpose, the suction shoe 16 has at least one suction pad 17, which comprises at least one slotted covering or several slidable strips. The suction pad 17 is indicated only by dashed lines.

Gemäß der Darstellung in der Figur 3 ist der in seiner Position einstellbare und an dem Entwässerungskasten 11 unmittelbar angeordnete Saugschuh 16 derart angeordnet, dass die eingebrachte und eine Schichthöhe H3 aufweisende Faserstoffsuspension 3 an einem Auftreffpunkt ATP zu Beginn der ersten Saugzone Z11.1 des Entwässerungskastens 11 auf das erste Sieb 4 aufläuft, von ihm also abgedeckt ist.As shown in the FIG. 3 the suction shoe 16, which can be adjusted in position and is arranged directly on the drainage box 11, is arranged such that the fibrous stock suspension 3 having a layer height H3 runs onto the first wire 4 at an impact point ATP at the beginning of the first suction zone Z11.1 of the drainage box 11, so covered by him.

Der in den drei Figuren 1 bis 3 beschriebene Doppelsiebformer 1 eignet sich in einem besonderen Maße zur Durchführung des erfindungsgemäßen Verfahrens zur Herstellung einer Faserstoffbahn, insbesondere einer Papier- oder Kartonbahn, aus mindestens einer Faserstoffsuspension 3 in einem Doppelsiebformer 1 einer Maschine zur Herstellung der Faserstoffbahn mit einer einen keilförmigen Einlaufspalt 6 aufweisenden Doppelsiebzone 2, die von zwei umlaufenden endlosen Sieben 4, 5 zumindest streckenweise gebildet wird, von denen das erste, über eine vorzugsweise positionierbare Einlaufwalze 10 geführte und anschließend die bereits eingebrachte Faserstoffsuspension 3 abdeckende Sieb 4 in der Doppelsiebzone 2 über mehrere mit gegenseitigem Abstand starr an einem vorzugsweise positionierbaren und mehrere Saugzonen Z11.1, Z11.2, Z11.3 umfassenden Entwässerungskasten 11 angeordnete Leisten 12 geführt wird und von denen das zweite, die eingebrachte Faserstoffsuspension 3 aufnehmende Sieb 5 in der Doppelsiebzone 2 über mehrere und gegenseitig der Leisten 12 des vorzugsweise positionierbaren und mehrere Saugzonen Z11.1, Z11.2, Z11.3 umfassenden Entwässerungskastens 11 angeordnete Leisten 13 geführt wird, die mittels nachgiebiger Elemente 14 abgestützt werden und die mit einer wählbaren Kraft F13 gegen das zweite Sieb 5 angedrückt werden.The one in the three FIGS. 1 to 3 described twin-wire former 1 is suitable in a particular extent for carrying out the method according to the invention for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension 3 in a Doppelsiebformer 1 a machine for producing the fibrous web with a wedge-shaped inlet gap 6 having twin-wire 2 , which is at least partially formed by two continuous endless screens 4, 5, of which the first, guided over a preferably positionable inlet roller 10 and then the already introduced pulp suspension 3 covering sieve 4 in the twin-wire zone 2 over a plurality of spaced apart rigidly at a preferably positionable and several suction zones Z11.1, Z11.2, Z11.3 comprehensive drainage box 11 arranged strips 12 is guided and of which the second, the introduced pulp suspension 3 receiving sieve 5 in the twin-wire zone 2 via me Leaders and mutually the strips 12 of the preferably positionable and a plurality of suction Z11.1, Z11.2, Z11.3 comprehensive drainage box 11 arranged strips 13 is guided, which are supported by resilient elements 14 and with a selectable force F13 against the second sieve 5 are pressed.

Dabei ist vorgesehen, dass das erste, die eingebrachte Faserstoffsuspension 3 noch nicht abdeckende Sieb 4 unmittelbar vor seiner Führung über die starr an dem Entwässerungskasten 11 angeordneten Leisten 12 durch den Wirkbereich W wenigstens eines an dem Entwässerungskasten 11 vorzugsweise in seiner Position D einstellbar angeordneten Saugschuhs 16 geführt wird, welcher infolge der vorzugsweise steuer-/regelbaren Besaugung des Wirkbereichs W das erste Sieb 4 von mitgeführten Substanzen entleert und sowohl die entleerten Substanzen als auch die vom ersten Sieb 4 mitgeführte Luft entfernt.It is provided that the first, the introduced pulp suspension 3 not yet covering sieve 4 immediately before his leadership on the rigidly arranged on the drainage box 11 strips 12 through the effective range W at least one of the drainage box 11 preferably in its position D arranged suction shoe 16th is guided, which emptied as a result of the preferably controllable / controllable suction of the effective range W, the first sieve 4 of entrained substances and removes both the deflated substances and entrained by the first sieve 4 air.

Auch eignet sich der in den drei Figuren 1 bis 3 beschriebene Doppelsiebformer 1 in einem besonderen Maße zur Durchführung der abhängigen Verfahrensansprüche.Also suitable in the three FIGS. 1 to 3 described twin-wire former 1 to a special extent for carrying out the dependent method claims.

Zusammenfassend ist festzuhalten, dass durch die Erfindung ein Verfahren und ein Doppelsiebformer der eingangs genannten Arten derart verbessert werden, dass eine Faserstoffsuspension auch bei höheren Geschwindigkeiten und überdies bei Herstellung einer qualitativ hochwertigen Faserstoffbahn entwässert werden kann und dass Störungen während des Blattbildungsprozesses aktiv entgegengewirkt werden kann. Die höheren Geschwindigkeiten liegen hierbei in einem Bereich von über 1.200 m/min, vorzugsweise von über 1.400 m/min, insbesondere von über 1.600 m/min.In summary, it should be noted that a method and a twin-wire former of the aforementioned types are improved by the invention so that a pulp suspension can be dewatered even at higher speeds and also in producing a high-quality fibrous web and that disturbances during the sheet forming process can be actively counteracted. The higher speeds are in this case in a range of over 1,200 m / min, preferably of over 1,400 m / min, in particular of over 1,600 m / min.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

11
Doppelsiebformertwin
22
Doppelsiebzonetwin
33
FaserstoffsuspensionFibrous suspension
44
Erstes SiebFirst sieve
55
Zweites SiebSecond sieve
5.15.1
FourdriniersiebFourdrinier
66
Einlaufspaltinlet gap
77
Stoffauflaufheadbox
88th
Stoffauflaufdüseheadbox
99
Lamellelamella
1010
Einlaufwalzeinlet roller
1111
Entwässerungskastendewatering box
1212
Leistestrip
1313
Leistestrip
1414
Nachgiebiges ElementResilient element
1515
Vorentwässerungszonepre-dewatering
1616
Saugschuhsuction shoe
1717
SaugbelagSaugbelag
1818
EinrichtungFacility
1919
Entwässerungselementdewatering element
AA
Positionierbarkeit (Bewegungsdoppelpfeil)Positionability (double movement arrow)
ATPATP
Auftreffpunktof impact
BB
Positionierbarkeit (Bewegungsdoppelpfeil)Positionability (double movement arrow)
CC
Besaugung (Pfeil)Aspiration (arrow)
DD
Positionierbarkeit (Bewegungsdoppelpfeil)Positionability (double movement arrow)
F11.1F11.1
Saugflächesuction
F13F13
Kraft (Pfeil)Force (arrow)
F16F16
Saugflächesuction
H3H3
Schichthöhelayer height
K11.1M11.1
Krümmungsradiusradius of curvature
K16K16
Krümmungsradiusradius of curvature
PP
Ablaufpunktthe end point
pU11.1pU11.1
Unterdruckvacuum
pU11.2pU11.2
Unterdruckvacuum
pU11.3pU11.3
Unterdruckvacuum
pU16pU16
Unterdruckvacuum
SS
Spaltweitegap width
WW
Wirkbereicheffective range
Z11.1Z11.1
Saugzonesuction zone
Z11.2Z11.2
Saugzonesuction zone
Z11.3Z11.3
Saugzonesuction zone
Z11.xZ11.x
Saugzonesuction zone

Claims (21)

  1. Method for manufacturing a fibrous web, in particular a paper or board web, from at least one fibrous suspension (3) in a twin wire former (1) belonging to a machine for manufacturing the fibrous web, having a twin wire zone (2) with a wedge-shaped inlet gap (6) which, at least in some sections, is formed by two circulating endless fabrics (4, 5), of which the first fabric (4), which is guided over an inlet roll (10) that can preferably be positioned and which subsequently covers the fibrous suspension (3) already introduced, is guided in the twin wire zone (2) over a plurality of foils (12) arranged rigidly at mutual intervals on a dewatering box (11) that can preferably be positioned and comprises a plurality of suction zones (Z11.1, Z11.2, Z11.3), and of which the second fabric (5), picking up the introduced fibrous suspension (3), is guided in the twin wire zone (2) over a plurality of foils (13) arranged opposite the foils (12) of the dewatering box (11) that can preferably be positioned and comprises a plurality of suction zones (Z11. 1, Z11.2, Z11.3), which foils (13) are supported by means of resilient elements (14) and are pressed against the second fabric (5) with a selectable force (F13), the first fabric (4) not yet covering the introduced fibrous suspension (3), immediately before it is guided over the foils (12) arranged rigidly on the dewatering box (11), being guided through the active region (W) of at least one suction shoe (16) which is arranged on the dewatering box (11) and which, as a result of the evacuation of the active region (W), preferably under open-loop/closed-loop control, empties the first fabric (4) of entrained substances and removes both the emptied substances and the air entrained by the first fabric (4),
    characterized in that
    the at least one suction shoe (16) arranged directly on the dewatering box (11) is designed such that its position (D) can be adjusted.
  2. Method according to Claim 1,
    characterized in that
    the suction shoe (16) of which the position (B) is adjustable and which is arranged directly on the dewatering box (11) is arranged in such a way that the fibrous suspension (3) introduced and having a layer height (H3) runs onto the first fabric (4) and is therefore covered by the latter in the first suction zone (Z11.1) of the dewatering box (11).
  3. Method according to Claim 1 or 2,
    characterized in that
    the suction shoe (16) of which the position (B) is adjustable and which is arranged directly on the dewatering box (11) is arranged in such a way that the fibrous suspension (3) introduced and having a layer height (H3) runs onto the first fabric (4) and is therefore covered by the latter at the start of the first suction zone (Z11.1) of the dewatering box (11).
  4. Method according to Claim 2 or 3,
    characterized in that
    the layer height (H3) of the fibrous suspension (3) is measured by using a gamma-gauge measurement or an electrical measuring principle, and
    in that the measured signal obtained is used for the open-loop/closed-loop control of the gap width (S) formed between the two fabrics (4, 5),
    the gap width (S) being the vertical distance of the first fabric (4) from the second fabric (5) at the point (P) at which the former runs off the inlet roll (10).
  5. Method according to one of the preceding claims, in particular according to Claim 4,
    characterized in that
    the inlet roll (10) guiding the first fabric (4), the suction shoe (16) emptying the first fabric (4) of entrained substances and removing both the emptied substances and the air entrained by the first fabric (4), and the dewatering box (11) comprising a plurality of suction zones (Z11.1, Z11.2, Z11.3) are positioned independently of one another.
  6. Method according to one of the preceding claims,
    characterized in that
    the second fabric (5) on the side opposite the first suction zone (Z11.1) of the dewatering box (11) is guided over a plurality of foils (13), which are supported by means of resilient elements (14) and which are pressed against the second fabric (5) with a selectable force (F13).
  7. Method according to one of the preceding claims,
    characterized in that
    the second fabric (5) on the side opposite all the suction zones (Z11.1, Z11.2, Z11.3) of the dewatering box (11) is guided over a plurality of foils (13), which are supported by means of resilient elements (14) and which are pressed against the second fabric (5) with a selectable force (F13).
  8. Twin wire former (1) for a machine for manufacturing a fibrous web, in particular a paper or board web, from at least one fibrous suspension (3), having two circulating endless fabrics (4, 5) which, at least in some sections, form with each other a twin wire zone (2) having a wedge-shaped inlet gap, of which fabrics the first fabric (4), which is guided over an inlet roll (10) that can preferably be positioned and which subsequently covers the fibrous suspension (3) already introduced, is guided in the twin wire zone (2) over a plurality of foils (12) arranged rigidly at mutual intervals on a dewatering box (11) that can preferably be positioned and comprises a plurality of suction zones (Z11.1, Z11.2, Z11.3), and of which the second fabric (5), picking up the introduced fibrous suspension (3), is guided in the twin wire zone (2) over a plurality of foils (13) arranged opposite the foils (12) of the dewatering box (11) that can preferably be positioned and comprises a plurality of suction zones (Z11.1, Z11.2, Z11.3), which foils (13) are supported by means of resilient elements (14) and are pressed against the second fabric (5) with a selectable force (F13), the first fabric (4) not yet covering the introduced fibrous suspension (3), immediately before it is guided over the foils (12) arranged rigidly on the dewatering box (11), being guided through the active region (W) of at least one suction shoe (16) which is arranged on the dewatering box (11) and which, as a result of the evacuation, preferably under open-loop/closed-loop control, of the active region (W), empties the first fabric (4) of entrained substances and removes both the emptied substances and the air entrained by the first fabric (4),
    characterized in that
    the at least one suction shoe (16) arranged directly on the dewatering box (11) is designed such that its position (D) can be adjusted.
  9. Twin wire former (1) according to Claim 8,
    characterized in that the suction shoe (16) of which the position (B) is adjustable and which is arranged directly on the dewatering box (11) is arranged in such a way that the fibrous suspension (3) introduced and having a layer height (H3) runs onto the first fabric (4) in the first suction zone (Z11.1) of the dewatering box (11) and is therefore covered by the said first fabric (4).
  10. Twin wire former (1) according to Claim 8 or 9,
    characterized in that
    the suction shoe (16) of which the position (B) is adjustable and which is arranged directly on the dewatering box (11) is arranged in such a way that the fibrous suspension (3) introduced and having a layer height (H3) runs onto the first fabric (4) and is therefore covered by the latter at the beginning of the first suction zone (Z11.1) of the dewatering box (11).
  11. Twin wire former (1) according to Claim 9 or 10,
    characterized in that
    a device (18) is provided to measure the layer height (H3) of the fibrous suspension (3) by using a gamma-gauge measurement or an electrical measuring principle, the measured signal obtained being used for the open-loop/closed-loop control of the gap width (S) formed between the two fabrics (4, 5), and the gap width (S) being the vertical distance of the first fabric (4) from the second fabric (5) at the point (P) at which the former runs off the inlet roll (10).
  12. Twin wire former (1) according to one of Claims 8 to 11, in particular according to Claim 11,
    characterized in that
    the inlet roll (10) guiding the first fabric (4), the suction shoe (16) emptying the first fabric (4) of entrained substances and removing both the emptied substances and the air entrained by the first fabric (4), and the dewatering box (11) comprising a plurality of suction zones (Z11.1, Z11.2, Z11.3) can be positioned independently of one another.
  13. Twin wire former (1) according to one of Claims 8 to 12,
    characterized in that
    the second fabric (5) on the side opposite the first suction zone (Z11.1) of the dewatering box (11) is guided over a plurality of foils (13), which are supported by means of resilient elements (14) and which are pressed against the second fabric (5) with a selectable force (F13).
  14. Twin wire former (1) according to one of Claims 8 to 13,
    characterized in that
    the second fabric (5) on the side opposite all the suction zones (Z11.1, Z11.2, Z11.3) of the dewatering box (11) is guided over a plurality of foils (13), which are supported by means of resilient elements (14) and which are pressed against the second fabric (5) with a selectable force (F13).
  15. Twin wire former (1) according to one of Claims 8 to 14,
    characterized in that
    the suction shoe (16) has an open suction area (F16) in the range from 10 to 90%, preferably from 30 to 49%.
  16. Twin wire former (1) according to one of Claims 8 to 15,
    characterized in that
    the suction shoe (16) has at least one suction cover (17) which comprises at least one slotted cover or a plurality of displaceable foils.
  17. Twin wire former (1) according to one of Claims 8 to 15,
    characterized in that
    the suction shoe (16) has a convex radius of curvature (K16) in the range from 300 to 6000 mm, preferably from 800 to 3000 mm.
  18. Twin wire former (1) according to one of Claims 8 to 17,
    characterized in that
    the first suction zone (Z11.1) of the dewatering box (11) has an open suction area (F11) in the range from 10 to 90%, preferably from 30 to 49%.
  19. Twin wire former (1) according to one of Claims 8 to 18,
    characterized in that
    the first suction zone (Z11.1) of the dewatering box (11) has a convex radius of curvature (K11.1) in the range from 300 to 10,000 mm, preferably from 800 to 6000 mm.
  20. Twin wire former (1) according to one of Claims 8 to 19,
    characterized in that
    it is constructed as a hybrid former known per se, the second fabric (5), picking up the introduced fibrous suspension (3), being a fourdrinier fabric (5.1) which, before it runs into the twin wire zone (2), is guided over a pre-dewatering zone (15).
  21. Twin wire former (1) according to one of Claims 8 to 19,
    characterized in that
    it is constructed as a gap former known per se, the inlet roll (10) guiding the first fabric (4) being a breast roll and the twin wire zone (2) running substantially horizontally or approximately horizontally, at an angle of inclination in relation to the horizontal or vertically or approximately vertically.
EP08150696A 2007-02-01 2008-01-28 Method for manufacturing a fibrous web and twin wire former for carrying out the method Not-in-force EP1953296B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102007000065A DE102007000065A1 (en) 2007-02-01 2007-02-01 Process for producing a fibrous web and twin-wire former for carrying out the process

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EP1953296B1 true EP1953296B1 (en) 2010-01-13

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AT (1) ATE455207T1 (en)
DE (2) DE102007000065A1 (en)

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DE102009027432A1 (en) 2009-07-02 2011-01-05 Voith Patent Gmbh Forming unit and method for producing a material web

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DE4002304A1 (en) 1990-01-26 1991-08-14 Escher Wyss Gmbh Paper forming stretch
CN100371528C (en) 2002-08-23 2008-02-27 美卓造纸机械公司 Forming of a paper or board web in a twin-wire former or in a twin-wire section of a former
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ATE455207T1 (en) 2010-01-15
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DE102007000065A1 (en) 2008-08-07

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