EP0471469B1 - Blattbildende Vorrichtung für eine Papiermaschine - Google Patents

Blattbildende Vorrichtung für eine Papiermaschine Download PDF

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Publication number
EP0471469B1
EP0471469B1 EP91306945A EP91306945A EP0471469B1 EP 0471469 B1 EP0471469 B1 EP 0471469B1 EP 91306945 A EP91306945 A EP 91306945A EP 91306945 A EP91306945 A EP 91306945A EP 0471469 B1 EP0471469 B1 EP 0471469B1
Authority
EP
European Patent Office
Prior art keywords
wire
hydroextractor
land
screens
hydroextractors
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
EP91306945A
Other languages
English (en)
French (fr)
Other versions
EP0471469A1 (de
Inventor
Takashi C/O Mihara Machinery Works Bando
Hiroshi c/o Hiroshima Technical Inst. Suzumura
Hiroshi c/o Hiroshima Technical Inst. Iwata
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.)
Mitsubishi Heavy Industries Ltd
Original Assignee
Mitsubishi Heavy Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Industries Ltd filed Critical Mitsubishi Heavy Industries Ltd
Publication of EP0471469A1 publication Critical patent/EP0471469A1/de
Application granted granted Critical
Publication of EP0471469B1 publication Critical patent/EP0471469B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • 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
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/48—Suction apparatus
    • D21F1/483—Drainage foils and bars

Definitions

  • the present invention relates to a sheet-forming apparatus for a paper machine.
  • two sheets made of woven wire form respective endless wire screen loops, between which the raw material liquid mixture (liquid plus fibres) is held and run; free water is removed from the raw material liquid mixture by various hydroextractors whereby a fibre mat grows gradually and a web is formed.
  • a jet of raw material mixture (liquid plus fibres) 7 is injected from a headbox 6 towards the gap 5 and is held between the two wire screen sheets 1,2 so as to run at the same speed as the wire screens.
  • Initial drainage starts when the raw material jet 7 is held between the two wire screens 1, 2 as a result of squeezing caused by the wire tension. However, most of the drainage is done subsequently on the shoe blades 9 by the pressure applied to the raw material mixture held between the wire sheets.
  • the reference number 10 denotes a water deflector and the reference number 11 denotes a low vacuum box for draining by vacuum.
  • FIGs. 6 and 7 of the accompanying drawings show two examples of typical prior art arrangements of the shoe blades and model curves in respective examples illustrating the pressure applied to the raw material mixture disposed between the wire screens.
  • each shoe blade 9 is detachably mounted to the hydroextractor 8 by means of a guide on a supporter 14 fixed to the hydroextractor 8 and is arranged so that the surface on the centre line has a prescribed curvature R. Therefore, the number of blades and the pitch between them are adjustable.
  • the angles ⁇ 1 and ⁇ 2 at which the wire screens 1 and 2 bend at the leading edge and at the trailing edge of the shoe, vary depending on the pitch (refer to Fig. 7). The greater the pitch is, the greater become the angles; the peak value of the generated pressure becomes greater accordingly.
  • the resulting pressure fibres in the raw material mixture held between the wire screens 1 and 2 are moved and dispersed further; simultaneously water is drained through both of the two wire screens.
  • the fibre mat 15" on the wire screen 2 side is subjected to a reaction force through the wire screen 2, when the wire screen 2 is scraped by the front edge of shoe blade 9.
  • a reaction force through the wire screen 2
  • the wire screen 2 is scraped by the front edge of shoe blade 9.
  • fibres in the mat are moved further and dispersed, whereby short fibres lose connection with long fibres and tend to be washed out with water drained by the pressure P1 to the mat 15", resulting in lower yield tendency of short fibres compared with the wire 1 side.
  • a convex dewatering suppression shoe is disposed within the loop of an upper of the two wire dewatering screens.
  • This shoe comprises a plurality of serrated shoe members each having a land portion for supporting the wire screen and an inclined portion forming a wedge-shaped hollow space between the surface of the wire screen and the surface of the shoe, upstream of said land portion. No other shoe portions exist between each land portion and the next wedge-shaped hollow space.
  • the wire-screen passes from one said land portion to the next and no provision is made for scraping up water upstream of each hollow wedge shaped portion. With the latter arrangement drainage can be obtained at one side only, thereby leading to reduced drainage performances.
  • a twin wire paper-sheet forming machine comprising two moving wire screen loops which cooperate together over part of their lengths to define a common line of travel, means for introducing a raw material of water and fibres to be formed into paper between the wire screens, and fixed hydroextractor means for removing the water from the raw material, the hydroextractor means having a convex surface defined by a plurality of spaced-apart shoe blades with land portions which contact a respective one of the wire screens, the hydroextractor means comprising at least two hydroextractors, the land portions of one of said at least two hydroextractors contacting one wire screen and the land portions of the other of said at least two hydroextractor contacting the other wire screen, the at least two hydroextractors being spaced alternately from one another along and on opposite sides of the line of travel of said wire screens and the lands of the shoe blades being contoured, each land having a front leading portion , a trailing back portion and a mid-portion located therebetween, and wherein said front
  • the trailing back portion of each land slope away from the respective wire screen along said line of travel of the wire screens.
  • the second hydroextractor in said line of travel has an adjustable support means to adjust the angle of contact of the leading portion of the lands thereof with the wire screen so as to avoid bending of the wire screen upon making contact with the shoe blades of the second hydroextractor.
  • the front edge of the shoe blade is formed so that the wire screens proceed without bending at that edge, the front edge functions only for scraping white water as in the case of a foil blade of a fourdrinier paper machine.
  • the fixed hydroextractors equipped with shoe blades are arranged alternately within the wire loop. Thereby, the effects of the shoe blades are directed alternately to the two sides of the mat being formed and thus there develops no difference between the top side and the back side of the resulting paper.
  • Initial set for the first fixed hydroextractor and for the second hydroextractor is made so that the two wire screens should not be bent at the back edge position of the last end of the first hydroextractor and at the front end position of the second fixed hydroextractor.
  • the wire tends to bend during operation due to added thickness of the raw material.
  • the structure of the second fixed hydroextractor is arranged to include said adjustable support means whereby, in a preferred arrangement, the second hydroextractor can be made so as to move rotationally around a centre near its back end whereby the wire screen can be supported without bending by adjusting the position of the front end in accordance with the thickness of the proceeding raw material.
  • Figure 1 shows one example of a sheet-forming apparatus in a paper machine having hydroextractors according to the present invention. Operating characteristics of the apparatus are shown in Fig. 2 and Fig. 3.
  • Fig. 4 is a detailed drawing of the device indicating how the decision is made as to the location of the front edge of the second fixed hydroextractor.
  • Constituent parts shown by the reference numbers 1 to 7 in Fig. 1 are identical with those used in Fig. 5 and function in essentially the same way. Thus, detailed explanations of these parts are omitted here.
  • Vacuum is applied to the space between shoe blades 9′. Therefore, drainage in the region between adjacent shoe blades 9′ is nearly the same as static drainage.
  • the drainage V in this latter region is performed separately from the location of fibre dispersion, that is, in nearly the same manner as for static drainage, with a high yield.
  • Wire screens 1 and 2 holding the raw material mixture 15 that has passed the front edge 9′a of the shoe blade, bend at the leading side of back edge 9′c with the angle of ⁇ 2′.
  • the shape of the back edge 9′c is made so that wire screens 1 and 2 must bend in this way.
  • the peak pressure value is adjustable by providing a first land portion 9′b of inclined, generally concave shape between the front edge 9′a and the back edge 9′c of the shoe blade 9′ and by selecting the parameters (l, ⁇ ) governing the wedge-shaped space formed by the inclined bottom surface and the wire screen 1.
  • the part near back edge 9'c of the shoe blade in said wedge-shaped space which is associated with a positive pressure P2' on the raw material mixture between the wire sheets, is filled with the white water which has drained, as taught in said prior art disclosure.
  • Fig. 3 shows another example of a shoe blade attaining the object of the present invention.
  • the functions of parts 9"a to 9"c in Fig. 3 are the same as those of 9'a to 9'c in Fig. 2.
  • Shoe blade 9" has a second land part 9"d declining towards the downstream side, in a similar manner to a file blade of a Fourdrinier paper machine. Vacuum force generated in the space formed by the second land part 9"d and wire screen 1 removes water, saving the vacuum force.
  • the drainage capacity is adjustable by changing angle ⁇ as is the case of a Fourdrinier paper machine.
  • the second fixed hydroextractor 11' is supported, as shown in Fig. 4, by a rotatable support device 16 whose supporting point 11'a is located near the back end and is set so that the wire screen 2 proceeds without bending at the front edge position of No. 1 (the front end) shoe blade 9'a by making the wire 2 lie at a distance from the shoe-blade corresponding to the thickness of raw material.
  • the rotatable position is adjusted by detecting the white water taken out at said front edge.
  • the mat running after the second hydroextractor 11′ has the same history at both sides and the difference between the top side and the back side is smaller, resulting in the achievement of a good yield of fine fibres.
  • the mat is despatched to the suction roll 12 under such conditions.
  • the function of the downstream equipment is the same as that of the prior art. It will be clear that the drainage at both sides of high yield rolls does not impair the characteristics of the formed mat.
  • a more inclined wire run in the direction of the wire screen movement at the contact point of wire 2 on suction roll 12 makes the treatment easier. (For reference, ⁇ ′ [Fig.1] > ⁇ [Fig.5]).
  • the yield is improved by separating the drainage locations to the machine side from the locations for fibre dispersion during drainage by the fixed hydroextractors. Furthermore, drainage zones for both sides of paper are separated and respective drainage control is possible. Moreover, by arranging the hydroextractors alternately in the two endless wire screen loops, difference between the top side and the back side of the paper is improved and the operational life of both wire screens become nearly the same because both wire screens run along similar fixed hydroextractors. Therefore, the life of both wire screens becomes nearly the same and the shut down period of the machine is shortened.

Landscapes

  • Paper (AREA)
  • Centrifugal Separators (AREA)

Claims (3)

  1. Blattbildende Papiermaschine mit zwei Drähten, umfassend zwei bewegte Drahtgeflechtkreise (1, 2), die über einen Teil ihrer Länge zusammenwirken und eine gemeinsame Bewegungslinie definieren, ein Mittel (6) zum Einleiten eines Rohstoffes aus Wasser und Fasern, der zwischen den Drahtgeflechten (1, 2) zu Papier geformt werden soll, und ein feststehendes Entwässerungsmittel zum Entfernen des Wassers aus dem Rohmaterial, wobei das Entwässerungsmittel eine konvexe Oberfläche aufweist, die durch eine Mehrzahl von voneinander beabstandeten Schuhblättern (9') mit Stegabschnitten definiert wird, die jeweils eines der Drahtgeflechte (1, 2) berühren, wobei das Entwässerungsmittel wenigstens zwei Entwässerungsvorrichtungen (8', 11') aufweist, wobei die Stegabschnitte einer (8') der wenigstens zwei Entwässerungsvorrichtungen ein Drahtgeflecht (1) und die Stegabschnitte der anderen (11') der genannten wenigstens zwei Entwässerungsvorrichtungen das andere Drahtgeflecht (2) berühren, wobei die wenigstens zwei Entwässerungsvorrichtungen (8', 11') abwechselnd an gegenüberliegenden Seiten der Bewegungslinie der genannten Drahtgeflechte (1, 2) voneinander beabstandet sind, dadurch gekennzeichnet, daß die Stege der Schuhblätter profiliert sind, wobei jeder Steg einen vorderen Führungsabschnitt (9'a), einen hinteren Rückabschnitt (9'c) und einen dazwischenliegenden Mittelabschnitt (9'b) aufweist, und dadurch, daß der genannte vordere Führungsabschnitt (9a')* flach ist und mit der genannten Bewegungslinie der Drahtgeflechte übereinstimmt, und der genannte Mittelabschnitt (9'b) durch eine keilförmige Wanne gebildet wird, wobei die Tiefe der Wanne von der Vorderseite zur Rückseite des Steges abnimmt, wobei die wenigstens zwei Entwässerungsvorrichtungen (8', 11') so strukturiert und angeordnet sind, daß nach Kontakt eines entsprechenden Drahtgeflechts (1, 2) mit dem vorderen Führungsabschnitt (9'a) jeder Strege die Drahtgeflechte (1, 2) auf den vorderen Führungsabschnitt (9'a) jedes Steges weitergehen, ohne sich an ihrer Vorderkante zu verbiegen, und wobei sich die Drahtgeflechte (1, 2) am hinteren Rückabschnitt (9'c) jedes Steges biegen.
  2. Maschine nach Anspruch 1, wobei der hintere Rückabschnitt (9'c) jedes Steges von dem jeweiligen Drahtgeflecht (1, 2) entlang der genannten Bewegungslinie der Drahtgeflechte weggeneigt ist.
  3. Maschine nach Anspruch 1 oder Anspruch 2, wobei die zweite Entwässerungsvorrichtung (11') in der genannten Bewegungslinie ein verstellbares Abstützmittel (16) aufweist, um den Kontaktwinkel des Führungsabschnittes seiner Stege mit dem Drahtgeflecht (2) so zu verstellen, daß ein Verbiegen des Drahtgeflechtes (2) nach dem Kontakt mit den Schuhblättern der zweiten Entwässerungsvorrichtung (11') zu vermeiden.
EP91306945A 1990-07-30 1991-07-29 Blattbildende Vorrichtung für eine Papiermaschine Expired - Lifetime EP0471469B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP199230/90 1990-07-30
JP2199230A JP2749971B2 (ja) 1990-07-30 1990-07-30 抄紙機の紙層形成装置

Publications (2)

Publication Number Publication Date
EP0471469A1 EP0471469A1 (de) 1992-02-19
EP0471469B1 true EP0471469B1 (de) 1996-05-08

Family

ID=16404320

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91306945A Expired - Lifetime EP0471469B1 (de) 1990-07-30 1991-07-29 Blattbildende Vorrichtung für eine Papiermaschine

Country Status (5)

Country Link
EP (1) EP0471469B1 (de)
JP (1) JP2749971B2 (de)
KR (1) KR940010026B1 (de)
DE (1) DE69119326T2 (de)
FI (1) FI110797B (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3422649B2 (ja) * 1997-04-15 2003-06-30 三菱重工業株式会社 抄紙機ツインワイヤフォーマの脱水機器
DE20104380U1 (de) * 2001-03-13 2001-06-28 Voith Paper Patent Gmbh Doppelsiebformer

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0369296A2 (de) * 1988-11-14 1990-05-23 Mitsubishi Jukogyo Kabushiki Kaisha Doppelsieb-Papiermaschine

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1382791A (en) * 1971-05-03 1975-02-05 Pulmac Research Ltd Vacuum drainage device
US3944464A (en) * 1974-05-10 1976-03-16 International Paper Company Forming section for twin-wire papermaking machine
JPS5434406A (en) * 1977-08-15 1979-03-13 Matsushita Electric Works Ltd Controlling of green sheet quality of paper making machine
FI75376C (fi) * 1982-04-30 1988-06-09 Valmet Oy Formningssko foer formare i pappersmaskin.
DE3513320A1 (de) * 1985-04-13 1986-10-23 Feldmühle AG, 4000 Düsseldorf Streichleiste fuer eine papiermaschine
JPS6229557A (ja) * 1985-07-29 1987-02-07 Otsuka Pharmaceut Factory Inc ジ低級アルキルフエノ−ル誘導体
US4790909A (en) * 1986-12-17 1988-12-13 Beloit Corporation Two-wire paper forming apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0369296A2 (de) * 1988-11-14 1990-05-23 Mitsubishi Jukogyo Kabushiki Kaisha Doppelsieb-Papiermaschine

Also Published As

Publication number Publication date
KR940010026B1 (ko) 1994-10-20
FI913534A0 (fi) 1991-07-23
DE69119326D1 (de) 1996-06-13
JP2749971B2 (ja) 1998-05-13
JPH0491287A (ja) 1992-03-24
EP0471469A1 (de) 1992-02-19
KR920002880A (ko) 1992-02-28
DE69119326T2 (de) 1996-09-19
FI913534A (fi) 1992-01-31
FI110797B (fi) 2003-03-31

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