EP0318107B1 - Method of formation of a fibrous web in a papermachine and apparatus for accomplishing the method - Google Patents

Method of formation of a fibrous web in a papermachine and apparatus for accomplishing the method Download PDF

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Publication number
EP0318107B1
EP0318107B1 EP88202647A EP88202647A EP0318107B1 EP 0318107 B1 EP0318107 B1 EP 0318107B1 EP 88202647 A EP88202647 A EP 88202647A EP 88202647 A EP88202647 A EP 88202647A EP 0318107 B1 EP0318107 B1 EP 0318107B1
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EP
European Patent Office
Prior art keywords
dewatering
deck
web
fabrics
elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP88202647A
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German (de)
English (en)
French (fr)
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EP0318107A1 (en
Inventor
Osmo Skyttä
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tampella Oy AB
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Tampella Oy AB
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Application filed by Tampella Oy AB filed Critical Tampella Oy AB
Priority to AT88202647T priority Critical patent/ATE69077T1/de
Publication of EP0318107A1 publication Critical patent/EP0318107A1/en
Application granted granted Critical
Publication of EP0318107B1 publication Critical patent/EP0318107B1/en
Anticipated expiration legal-status Critical
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Classifications

    • 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 of forming a fibrous web by draining in a papermachine, the method being more precisely defined in the preamble of Claim 1.
  • the invention also relates to a web forming zone by means of which said method can accomplished and which is defined in the preamble of Claim 6.
  • twin-wire web forming zones of a papermachine so called formers
  • formers have been the object of intensive development work during the past two decades.
  • the known constructions can be divided in three basic types, namely roll formers, blade formers and forcibly-guided gap formers.
  • the so-called blade formers include a gap formed by two wires as well, but in this case the curvature is achieved by means of the blades of the foils being mounted along the direction of the web at the periphery of a large circle.
  • the radius of curvature may be several metres. If the web travelled following the arc of said circle, the average pressure so formed would be lower.
  • the wires and the web therebetween travel, however, straight from one blade to another, forming a polygon and the blades of the foils impart pressure impacts to the web as it travels over the blade.
  • the forcibly-guided gap being constituted of stationary dewatering means is well known.
  • This type forms the object of the present invention.
  • the gap is adjustable and it converges in the travelling direction of the web.
  • the pressure developed in the web presses water through decks having holes or slits and into dewatering boxes divided into separate chambers in the cross machine direction. From each chamber the water is removed via a control valve back to the circulation. By adjusting the valves the pressure and consequently also the dewatering circumstances can be largely controlled.
  • a gap former of the above type is disclosed e.g. in Finnish publication No. 63077 of accepted patent application and in US-Patents Nos. 3823062 and 3847731.
  • the purpose is achieved with a method the characteristics of which are presented by the characterising portion of Claim 1.
  • the apparatus making it possible to achieve the above-mentioned advantages comprises features presented by the characterising portion of Claim 6.
  • a controlled filtering of water from the stock suspension can be achieved and the deflection of the boxes as a result of pressure is avoided.
  • the deck elements can be arranged to effect a load separately from each other, each with a desired force on the wire.
  • the forming of flocks can also be prevented by means of a suitable mechanical high-frequence vibration or steam implosion.
  • the invention has further various advantageous constructional alternatives, e.g.
  • the deck elements can be supported in the frame of the machine by means of resilient means effecting resiliency either in such a manner that they are fastened onto the dewatering spaces, which in turn are fixed through said resilient means on the machine frame or on a part stationary in relation to the frame during the dewatering, or in such a manner that the resilient means allowing the resiliency support the deck elements on the structure of the dewatering spaces and the latter are stationary in relation to the machine frame or to a part stationary in relation to the frame during the dewatering.
  • the dewatering spaces can be adjustable with mechanisms known per se into a suitable position with regard to the machine frame for adjusting the width of the gap.
  • the generating of the resilient load force in accordance with the invention, i.e. the load pressure, on the stock suspension creates a filtering pressure therein and effects controlled drainage making it possible to obtain an evenly growing fibrous layer deposited on both wires.
  • the layer acts as a filter for the remaining suspension.
  • the invention makes it possible to effect drainage in so slow a manner as possible in a long narrow gap and the filtering can be so effected that a thinner region which naturally is more pervious to water tham the surrounding regions receives more flow of fibres.
  • the formation of flocks can so be avoided in order to obtain best possible quality of paper.
  • the dewatering is controllable in particular at this initial stage. It is also important, that the formation of flocks, which the fibres tend to do, can be prevented and flocks that are already formed can be broken down until later dewatering stages where flocks are no more formed after the fibres are bound together to a uniform fibrous network.
  • a gap 13 of the web forming zone of the invention is formed by a wedge-shaped space that is formed between two wires 1 and 2.
  • the wires 1 and 2 travel in a manner known per se over their respective breast rolls 4 and after wrapping round said rolls within a predetermined sector they converge, travelling upwards towards each other, forming the above-mentioned space, and join on a forming roll 3 with a large diameter (2000 mm).
  • the wires 1 and 2 travel at the location of the gap 13 following a straight path and forming the walls of the gap. In this portion the wires are supported by dewatering boxes on their opposite sides, said boxes having decks provided with slits.
  • the boxes supporting the wire 1 are designated 5 and the boxes supporting the wire 2 are designated 6.
  • Fig 1b shows the construction of the gap in more detail.
  • the wire 1, constituting in this case the primary wire is supported by deck elements 11a, 11b, etc. of the dewatering boxes 5a, 5b, etc. being situated one after the other in the direction of travel of the wire.
  • the dewatering boxes 5 are in turn rigidly supported by a frame beam 8 in the machine.
  • the wire 2, constituting in this case the secondary wire is on its opposite side supported by deck elements 12a, 12b, etc. of the dewatering boxes 6a, 6b, etc. being situated one after the other in the direction of travel of the wire, and the deck elements are provided with holes or slits. Said deck elements are fixed on the dewatering boxes 6 immovably with regard to the boxes.
  • the bottom parts of the dewatering boxes 6 are at least at both ends of the boxes resiliently supported by a frame beam 9 in the machine through pneumatic bellows 7 (Fig. 1a).
  • a frame beam 9 in the machine through pneumatic bellows 7 (Fig. 1a).
  • bellows 7 In the longitudinal direction of a single box, i.e. in the cross machine direction, there is preferably several bellows 7 supporting it.
  • a wet suction box 10 being situated after the plurality of the resiliently supported boxes 6, and this box supports both wires before they are wrapped round the roll 3.
  • the wire 2 is supported by a plurality of successive boxes 6a, 6b, each of them being mounted on the frame beam 9 through its own bellows 7a, 7b respectively.
  • the bellows are supported on one side on the bottom parts of their respective boxes and on the other side they are fixed on the frame beam 9. Since said dewatering boxes are arranged successively in the direction of travel of the web and each of them is separately caused to effect a load with a predetermined force on the wire, it is possible to obtain such dewatering profile as desired in the machine direction of the former.
  • the dewatering boxes 6 can further be adjustable with the aid of any known suitable mechanism into a suitable predetermined position before the dewatering process is started, so that the width of the gap can be adjusted.
  • Fibrous suspension i.e. stock
  • Fibrous suspension i.e. stock
  • a high-frequency mechanical vibration preferably within ultrasonic range, is supplied into the stock for breaking down the flocks, or at this point steam implosion is utilised.
  • the point of breaking down the flocks is designated by arrow A in Fig. 1.
  • the mechanical vibration can be effected e.g. by means of the first resiliently supported deck element 12a as seen in the direction of supply of the stock.
  • the gap 13 tapers slowly in the direction of travel of the wires so as to bring about gentle dewatering. Unneccessary violent changes in pressure, possible damages and a complicated control system which otherwise would be present are avoided in fact by arranging the above-mentioned boxes 6a, 6b etc. on the side of the secondary wire 2 to be resiliently supported by the frame of the machine.
  • the resiliency is accomplished by introducing into the bellows assemblies 7a, 7b etc. a suitable pressure of a compressible medium, such as air, in which event each deck element 12a, 12b, etc. is used in effecting a load with a desired force Fa, Fb, etc., respectively, on the wire without any deflection of the boxes in their longitudinal direction. Even a slight deflection in a box would result in variations in thickness in the web in cross machine direction, which in turn would result in the paper so manufactured being refuse.
  • Each deck element 12a, 12b, etc. is caused to effect a load with a desired force Fa, Fb, etc., respectively, on the wire 2 separately of each other. This results in a controlled dewatering process along the length of the gap.
  • the water drained through the wires 1 and 2 on both sides is squeezed into the boxes 5 and 6, wherefrom it is led back into the circulation system in a manner known per se. Because the dewatering is effected by means of the filtering pressure, no suction is needed in this case. However, the dewatering boxes can be provided with reduced pressure for example by means of a so-called suction-leg. Further, it is important to be able to control the amount of water drained away from the different sides of the web. This can be realised in the former of the invention in two ways, on one hand in a manner of well-known forcibly-guided formers by adjusting the amount of water removed from the boxes e.g. using flow restricting devices, as described in Finish publication No. 63077 of accepted patent application and in US-Patent 3823062, or alternatively by equipping the boxes with replaceble deck elements having varying open area.
  • the second portion of the former is reached, this portion of the former being formed by a roll 3 with an open surface and a large diameter (2000 mm).
  • the joint run of the wires wraps round the periphery of the roll over a predetermined sector and it will be directed on the side of the primary wire 1.
  • the dewatering takes place due to the tensioning of the secondary wire 2, and the dewatering pressure is now constant, giving optimum retention as result.
  • Fig. 2 illustrates one embodiment of the apparatus according to the invention, shown as a side view.
  • the embodiment includes stationary dewatering spaces and deck elements with the resilient load upon the wire and being supported by the dewatering spaces.
  • the single dewatering box 6 is divided in compartments 6a, 6b etc.
  • Corresponding deck elements 12a, 12b etc. at the location of respective compartments are loose from the dewatering box 6.
  • Each deck element comprises elongate support bars 16,aligned parallelly to the direction of travel of the wire 2 and including ceramic dewatering ribs or foils 17 fixed on the bars, extending transversely in relation of the direction of travel of the wire and lying against the reverse side of the wire 2.
  • the deck elements are connected to each other successiveively through an endwise joining arrangement of the supporting bars 16 by means of notched junctions 18 being formed at the ends of the support bars and enabling the bars 16 to move in a direction perpendicular to the plane of the wire 2.
  • a transverse support bar 19 supporting the point of junction of two successive deck elements.
  • a trough- or gutter-shaped elongate member 20 extending transversely in relation to the direction of travel of the wire and accommodating a pneumatic load-hose or -tube 7′, which is in contact with the support bar 19 at the junction of the deck elements and extends parallelly to said bar.
  • the operational principle of the pneumatic load-hose or -tube 7′ is similar to that of the bellows in Fig. 1a.
  • the adjustment of the pressure prevailing within the hose or tube 7′ results in a movement due to the deformation of the hose or tube, the movement causing a change in the position of the successive deck elements 12a, 12b with regard to the dewatering box 6.
  • a desired filtering pressure can be created in the flow passing within the gap at the location of each deck element 12a, 12b, etc. according to the invention.
  • the lowermost deck element with resilient load can be supported at its lower edge by the suction box 6 and the following elements can be successiveively supported by the upper edges of the respective preceding lower elements by means of the notched junctions 18.
  • the mounting of the deck elements is ensured with the aid of safety springs 20 attached thereto and which at their opposite end can be affixed for example onto the bottom part of the dewatering spaces 6a, 6b, etc.
  • the invention can be of course be modified without departing from its idea represented by the accompanying claims. It is essential that the invention provides a long gap converging in the direction of the travel and making it possible to produce paper from stock as a result of a controllable drainage.
  • This control is based on creating a filtering pressure by dewatering boxes, which exert load with a desired and suitable force on the stock layer travelling between the wires. Due to the long gap the stock layer is at each portion of the gap exposed to a uniform pressure for a sufficiently long time resulting in equalising of grammage in the web so produced.

Landscapes

  • Paper (AREA)
  • Artificial Filaments (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
  • Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
EP88202647A 1987-11-25 1988-11-24 Method of formation of a fibrous web in a papermachine and apparatus for accomplishing the method Expired - Lifetime EP0318107B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT88202647T ATE69077T1 (de) 1987-11-25 1988-11-24 Verfahren zur formung einer faserbahn in einer papiermaschine und vorrichtung zur durchfuehrung des verfahrens.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI875196A FI85885C (fi) 1987-11-25 1987-11-25 Foerfarande foer formering av en fiberbana i en pappersmaskin samt en anordning foer utfoering av foerfarandet.
FI875196 1987-11-25

Publications (2)

Publication Number Publication Date
EP0318107A1 EP0318107A1 (en) 1989-05-31
EP0318107B1 true EP0318107B1 (en) 1991-10-30

Family

ID=8525469

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88202647A Expired - Lifetime EP0318107B1 (en) 1987-11-25 1988-11-24 Method of formation of a fibrous web in a papermachine and apparatus for accomplishing the method

Country Status (6)

Country Link
EP (1) EP0318107B1 (fi)
JP (1) JPH01162891A (fi)
AT (1) ATE69077T1 (fi)
CA (1) CA1335046C (fi)
DE (1) DE3865949D1 (fi)
FI (1) FI85885C (fi)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4009627A1 (de) * 1990-03-26 1991-10-10 Voith Gmbh J M Leiste zur nachgiebigen stuetzung eines siebbandes
DE4028126C2 (de) * 1990-09-05 1993-10-14 Escher Wyss Gmbh Schlitzdüse, insbesondere für einen Doppelsiebformer und deren Verwendung in einem Doppelsiebformer
US5766419A (en) * 1996-07-23 1998-06-16 Valmet Corporation Twin-wire gap former in a paper machine
FI109210B (fi) * 1998-11-24 2002-06-14 Metso Paper Inc Menetelmä ja laite selluloosarainan muodostamiseksi
GB0030682D0 (en) 2000-12-15 2001-01-31 Astenjohnson Inc Suction assisted skimmer blade
GB2370046A (en) 2000-12-15 2002-06-19 Astenjohnson Inc Adjustable resilient blade support
CN110396850B (zh) * 2019-07-10 2020-09-11 湖北金庄科技再生资源有限公司 一种造纸机网部纸页脱水成型装置和纸页进行脱水的方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3138133C2 (de) * 1981-09-04 1986-03-06 Sulzer-Escher Wyss GmbH, 7980 Ravensburg Entwässerungseinheit für Langsieb-Papiermaschinen

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1723051A (en) * 1928-03-16 1929-08-06 Mantius Otto Method of making fiber board
DE1277203B (de) * 1965-05-08 1968-09-12 Klein Kg A Bandfilter zum Entwaessern insbesondere der bei der Abwasseraufbereitung anfallenden, eingedickten Suspensionen
AT322963B (de) * 1970-10-30 1975-06-25 Arledter Hanns F Dr Ing Verfahren zur blattbildung bei einer doppelsieb-papiermaschinen
GB2174120B (en) * 1985-04-26 1988-08-10 Doerries Gmbh Apparatus for guiding the wires of a twin wire forming section of a paper or cardboard machine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3138133C2 (de) * 1981-09-04 1986-03-06 Sulzer-Escher Wyss GmbH, 7980 Ravensburg Entwässerungseinheit für Langsieb-Papiermaschinen
DE3153305C2 (de) * 1981-09-04 1986-10-23 Sulzer-Escher Wyss GmbH, 7980 Ravensburg Entwässerungseinheit für Langsieb-Papiermaschinen

Also Published As

Publication number Publication date
DE3865949D1 (de) 1991-12-05
CA1335046C (en) 1995-04-04
FI85885C (fi) 1992-06-10
FI85885B (fi) 1992-02-28
EP0318107A1 (en) 1989-05-31
ATE69077T1 (de) 1991-11-15
FI875196A0 (fi) 1987-11-25
FI875196A (fi) 1989-05-26
JPH01162891A (ja) 1989-06-27

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