EP0468005B1 - Arrangement for guiding a web from the press part to the dryer part of a papermaking machine - Google Patents

Arrangement for guiding a web from the press part to the dryer part of a papermaking machine Download PDF

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Publication number
EP0468005B1
EP0468005B1 EP91901763A EP91901763A EP0468005B1 EP 0468005 B1 EP0468005 B1 EP 0468005B1 EP 91901763 A EP91901763 A EP 91901763A EP 91901763 A EP91901763 A EP 91901763A EP 0468005 B1 EP0468005 B1 EP 0468005B1
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EP
European Patent Office
Prior art keywords
web
felt
belt
press
transfer felt
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
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EP91901763A
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German (de)
French (fr)
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EP0468005A1 (en
Inventor
Albrecht Meinecke
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JM Voith GmbH
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JM Voith GmbH
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Publication of EP0468005A1 publication Critical patent/EP0468005A1/en
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Publication of EP0468005B1 publication Critical patent/EP0468005B1/en
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/0209—Wet presses with extended press nip
    • D21F3/0218—Shoe presses
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F5/00—Dryer section of machines for making continuous webs of paper
    • D21F5/02—Drying on cylinders
    • D21F5/04—Drying on cylinders on two or more drying cylinders
    • D21F5/042—Drying on cylinders on two or more drying cylinders in combination with suction or blowing devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G9/00—Other accessories for paper-making machines
    • D21G9/0063—Devices for threading a web tail through a paper-making machine

Definitions

  • the invention relates to an arrangement for transferring a fibrous web, preferably paper web (hereinafter referred to as "web"), from the press section to the dryer section of a paper machine, in particular with the features specified in the preamble of claim 1.
  • web preferably paper web
  • it is an arrangement in which an endless belt running through the last press nip of the press section, which is designed as a water-absorbent felt belt, has a double function: the felt belt takes at least part of the im-press nip from the web in the usual way squeezed out water to remove it.
  • this felt belt guides the web from the press section into the dryer section, running together with the web at least over the first dryer cylinder of the dryer section.
  • This felt tape is therefore called “transfer felt” below.
  • the last press of the press section has only a single felt belt, namely a bottom felt, which at the same time has the function of the transfer felt.
  • the web to be dewatered thus comes into direct contact with the top roller of the last press.
  • This top roller therefore has a smooth and generally hard outer surface, for example formed from granite or artificial stone. It is generally known that in such an arrangement the web adheres to the top roller a little behind the press nip and with a certain tension from the top roller must be deducted.
  • the web runs at least a short distance, ie without support from the transfer felt.
  • the first drying cylinder of the dryer section is arranged within the loop of the transfer felt. The web therefore does not come into direct contact with this first drying cylinder. This results - particularly at high working speeds - in the danger that the paper web will lift off from the transfer felt due to the centrifugal force on the first drying cylinder.
  • a disadvantage of this arrangement is that the web comes into contact with the relatively hard and coarse dryer fabric very early, ie while it is still relatively moist and soft. As a result, there is a risk that the dryer fabric leaves permanent impressions in the paper web. Such embossings may be accepted for coarse paper types, which are intended for packaging purposes, for example, but not, for example, for printing and writing papers. In addition, the adherence of the paper web to the relatively coarse surface is not always guaranteed, especially at high speeds.
  • the essence of the invention consists in the combination of the previously only individually known features, namely guiding the web through the last press of the press section between two belts (of which the "first belt” as before also functions as the transfer felt running from the press section to the dryer section has) and separating the web from the "second belt” by means of a separating device which works in such a way that a free web tension is avoided.
  • This achieves two effects at the same time: firstly, any longitudinal stretching of the paper web within the press section and when transferring it to the dryer section is avoided; on the other hand, the transfer felt is heated as it runs over at least the first drying cylinder of the dryer section, so that it returns to the last press at a higher temperature than before. This increases the drainage capacity of the last press; because the heated felt now has a lower flow resistance for the water to be absorbed from the paper web.
  • the transfer felt performs a third function by pressing the web at least onto the first dryer cylinder of the dryer section.
  • the arrangement is such that the web always comes into direct contact with that drying cylinder or drying cylinders over or over which the transfer felt runs. This ensures that the drying of the web starts quickly from the start.
  • an additional felt or wire belt is required on the drying cylinder (s) mentioned in order to keep the web in contact with the transfer felt.
  • the paper web in the initial area of the dryer section (ie at least on the first drying cylinder) is pressed by the transfer felt onto the drying cylinder or cylinders. Since the transfer felt, as already mentioned, has a fine structure, the risk in the initial area of the dryer section is avoided that permanent impressions are caused in the paper web, as can be caused by a much coarser dryer fabric. In other words, the invention makes it much easier than before to produce fine papers with the desired high quality properties.
  • the separating device mentioned in claim 1 and required behind the last press nip can be carried out in quite different ways: a suction box or a suction roller can be provided in a known manner. Or a first suction guide roller of the dryer section is used as a separating device. The arrangement of such a suction guide roller in front of the first drying cylinder is often desirable in order to obtain the largest possible wrap angle on the first drying cylinder.
  • this will preferably be designed as a long-gap press; i.e. has one of the two rollers - instead of a normal one, e.g. metallic roller shell - a flexible circumferential (tubular or band-shaped) pressing element which can be pressed onto the other roller by means of a support device (preferably a press shoe).
  • a support device preferably a press shoe
  • the transfer felt can take over either the function of the bottom felt or the function of the top felt in the last press. Both variants are described in detail below.
  • the "second endless belt" required according to claim 1 can either - like the transfer felt - be designed as a water-absorbent felt belt; or it is designed as an elastic press belt with a relatively low water absorption capacity.
  • the second band directly forms the flexible (tubular or band-shaped) pressing element of an extended-gap press. In this case, only a single water-absorbent felt belt (namely the transfer felt) is provided in the last press.
  • measures will be taken which serve to further increase the drainage capacity of the last press, namely by reducing the rewetting of the web behind the press nip as far as possible.
  • it can be provided to guide the transfer felt a little behind the press nip without the web over an auxiliary guide roller and from there back to the separating device.
  • the web runs behind the press nip initially only with the second belt and then changes on the separating device, which is designed as a take-off suction roll, onto the transfer felt.
  • the press shoe according to DE-OS 38 15 278 can be used design in such a way that it also takes over the function of the separating device, the rewetting of the web also being reduced.
  • Fig. 1 shows schematically the last press and the first dryer group of a paper machine.
  • FIGS. 2 and 4 to 6 show modifications of the arrangement according to FIG. 1.
  • FIG. 3 shows a cross section through the press shoe of an extended-nip press roll (enlarged detail from FIG. 2).
  • FIG. 1 shows a section of a paper-making machine with part of the press section 10 and with the beginning part of a drying section 20.
  • a double-felt press with an upper long-nip press roll 14 and with a counter-roll 13 below is first seen the long nip press roll 14 are shown schematically, a flexible circumferential tubular press jacket 14a and a press shoe 14b with which the press jacket can be pressed against the counter roll.
  • the usual stationary support body in which the press shoe 14b can slide in the radial direction and all other details are omitted.
  • the extended press nip formed by the press jacket 14a and the counter roll 13 is designated by 19.
  • a bottom felt 11, an upper felt 12 and the paper web 9 to be dewatered (and then dried) run through it. This is removed from a preceding felt belt 8 by means of a take-off suction roller 16 located in the upper felt 12.
  • the two felt belts 11 and 12 are usually designed as usual as water-absorbent wet felts.
  • a flexible press belt can be provided instead of the upper felt 12, the water absorption capacity of which is less than that of the lower felt 11.
  • the lower felt 11 also serves as a transfer felt; i.e. it transfers the paper web 9 from the press section 10 into the drying section 20. It is essential that the transfer felt 11 also serves to press the paper web 9 onto at least the first drying cylinder 21, preferably onto a group of, for example, four drying cylinders 21 and 22. Therefore, all of these drying cylinders 21, 22 lie outside the endless loop of the transfer felt 11.
  • both felt belts 11 and 12 (together with the paper web in between) can run together to a separating device 17.
  • a separating device 17 This is in Fig. 1 in the loop of the transfer felt 11 and is designed as a suction roll with a removal suction zone 17a, so that from here the paper web 9 runs together with the transfer felt 11.
  • FIG. 1 An alternative is shown in FIG. 1 with dash-dotted lines: the transfer felt 11 is diverted behind the press nip 19 without the web 9 via an auxiliary guide roller 42 and then runs back to the separating device 17. In the area of this diversion, the transfer felt 11 is conditioned, for example by the fact that the separating device 17 designed as a suction roll has a conditioning suction zone 17b.
  • the auxiliary guide roller 42 can be designed as a suction roller or as a blowing roller; or a pipe suction device is provided (Fig. 4, number 43).
  • the transfer felt 11 runs together with the paper web 9 over a guide roller 23.
  • a guide roller 24, 25 is provided behind each of the drying cylinders 21, 22. These guide rollers are all located within the loop of the transfer felt 11, so that the paper web 9 is in the area of the guide rollers on the outside of the transfer felt and is therefore subject to a certain centrifugal force.
  • the guide rollers 23, 24, 25 are designed in a known manner as suction rollers. From the last suction guide roll 25, the transfer felt 11 runs over an adjustable guide roll 26 and over further guide roll 27 back to the guide roll 15 of the press section 10. Between the guide rolls 25 and 26, the paper web 9 is fed with the help of a further felt belt or dryer fabric 28 and with the help of a take-off suction roll 29 removed from the transfer felt 11 and fed to a subsequent drying station, not shown.
  • the drying cylinders 21 and 22 form an essentially vertical row of cylinders. Instead, the drying cylinders could also be arranged in an essentially horizontal row.
  • FIG. 2 in contrast to FIG. 1, the long nip press roll 14 is arranged below the counter roll 13.
  • a special separating device (as in FIG. 1, item 17) is not provided for separating the upper felt 12 from the paper web 9 and from the transfer felt 11.
  • Both other variants are shown. According to the first variant shown in full lines, both felt belts 11 and 12 run together with the paper web in between up to the first suction guide roller 23a. If necessary, this can have a pre-suction zone 23b, which lies in front of the point where the two felts run onto the suction guide roller. The top felt then runs over a guide roller 18a and the further guide rollers 18 back to the take-off suction roller 16.
  • the two felt belts 11 and 12 separate shortly behind the outlet from the extended press nip 19. This is aimed at to rewet the press nip 19 behind the press nip Reduce paper web from the top felt 12 as much as possible.
  • the press shoe 14b according to FIG. 3 (as known per se from DE-OS 38 08 293):
  • the press shoe 14a is divided into an upper part 34 and a lower part 35 acting as a piston.
  • the latter is shown in FIG a pressure chamber 32 arranged; This is a recess of the fixed support body 31. Sealing strips and associated sealing strip supports 38 and 39 are used to guide the press shoe and to seal the pressure chamber 32.
  • the middle part of the sliding surface 33 of the press shoe upper part 34 forms the concave-shaped contact surface with the width b.
  • the press shoe upper 34 has a convexly curved guide surface 36.
  • the radius of curvature K thereof can be approximately equal to the radius R of the orbit of the press cover 14a.
  • Air can enter the upper felt 12 between the positions A and B, so that the paper web 9 safely detaches from the upper felt 12 at the point B and moves with the lower felt (transfer felt 11) (in the direction of the suction guide roller 23a, FIG. 2).
  • the width of the guide surface 36 (in the direction of web travel) is designated by d.
  • Fig. 4 differs from Fig. 1 in that there is no top felt in the press.
  • the tubular press jacket 14a of the extended-nip press roll 14 assumes the function of the second belt (provided according to claim 1).
  • the non-rotating (radially displaceable) press shoe 14b can be replaced by a rotatable roller body 46, as indicated by dash-dotted lines.
  • the transfer felt 11 is diverted behind the press nip 19 without the web 9, namely past a pipe suction device 43 and via an auxiliary guide roller 42 and finally back to the one designed as a suction roller Separating device 17. This is arranged such that the inflatable press jacket 14a forms a small looping zone on the suction roll 17.
  • a take-off suction roll 15 ' is provided in the loop of the transfer felt 11, which ensures that the web 9 changes from the preceding felt belt 8 to the transfer felt 11.
  • the bottom felt 11 of the last press 13, 14 has the function of the transfer felt.
  • the arrangement is such that the top felt 11 'has the function of the transfer felt, the top roller being designed as an extended-nip press roller 14.
  • the bottom felt is designated 12 '.
  • the press shoe 14b can in turn be designed according to FIG. 3, so that the two felt belts 11 'and 12' separate at the outlet end of the press shoe.
  • scrapers 40 are indicated, which rest on the free part of the cylinder surfaces. Such scrapers are also present in the construction according to FIGS. 1, 2 and 4, but are omitted in the drawing.
  • hot air blow boxes 41 are also indicated, which blow hot air onto the paper web at the suction guide rollers 24 and which can additionally extract exhaust air.
  • Fig. 6 differs from Fig. 5 only in that - similar to Fig. 2 - the lower roll is designed as an extended-nip press roll 14. Behind the press nip, the transfer felt (top felt 11 ') without the web 9 is guided via two auxiliary guide rollers 44 and 45 to a separating device 17' designed as a take-off suction roller.
  • the felt conditioning devices already mentioned above are not shown in FIG. 6.

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  • Paper (AREA)
  • Drying Of Solid Materials (AREA)
  • Advancing Webs (AREA)

Abstract

PCT No. PCT/EP91/00049 Sec. 371 Date Oct. 2, 1991 Sec. 102(e) Date Oct. 2, 1991 PCT Filed Jan. 15, 1991 PCT Pub. No. WO91/12370 PCT Pub. Date Aug. 22, 1991.Arrangement for the transfer of a paper web from the press section 10 to the dryer section 20 of a paper machine, where a water-absorbent felt belt 11 of the last press 13, 14 has at the same time the function of a transfer felt 11; i.e., the transfer felt 11 transports the paper web 9 from the press section 10 to the dryer section 20. There, the transfer felt serves to force the paper web onto at least the first drying cylinder 21. This drying cylinder and additional drying cylinders 22 lie therefore outside the continuous loop of the transfer felt 11.

Description

Die Erfindung betrifft eine Anordnung zum Überführen einer Faserstoffbahn, vorzugsweise Papierbahn (nachfolgend kurz "Bahn" genannt), Von der Pressenpartie zur Trockenpartie einer Papiermaschine, im einzelnen mit den im Oberbegriff des Anspruches 1 angegebenen Merkmalen. Danach handelt es sich um eine Anordnung, bei der ein durch den letzten Preßspalt der Pressenpartie laufendes endloses Band, das als ein wasseraufnahmefähiges Filzband ausgebildet ist, eine Doppelfunktion ausübt: Das Filzband nimmt in der üblichen Weise zumindest einen Teil des im - Preßspalt aus der Bahn ausgepreßten Wassers auf, um es abzutransportieren. Außerdem führt dieses Filzband die Bahn von der Pressenpartie in die Trockenpartie, wobei es zusammen mit der Bahn zumindest über den ersten Trockenzylinder der Trockenpartie läuft. Dieses Filzband wird deshalb nachfolgend "Überführfilz" genannt.The invention relates to an arrangement for transferring a fibrous web, preferably paper web (hereinafter referred to as "web"), from the press section to the dryer section of a paper machine, in particular with the features specified in the preamble of claim 1. According to this, it is an arrangement in which an endless belt running through the last press nip of the press section, which is designed as a water-absorbent felt belt, has a double function: the felt belt takes at least part of the im-press nip from the web in the usual way squeezed out water to remove it. In addition, this felt belt guides the web from the press section into the dryer section, running together with the web at least over the first dryer cylinder of the dryer section. This felt tape is therefore called "transfer felt" below.

Eine derartige Anordnung ist bekannt aus EP 0346659. Sie weist im einzelnen die folgenden Merkmale auf: Die letzte Presse der Pressenpartie hat nur ein einziges Filzband, nämlich einen Unterfilz, der zugleich die Funktion des Überführfilzes hat. Somit kommt die zu entwässernde Bahn in unmittelbaren Kontakt mit der Oberwalze der letzten Presse. Diese Oberwalze hat deshalb eine glatte und im allgemeinen harte, z.B. aus Granit oder Kunststein gebildete Mantelfläche. Es ist allgemein bekannt, daß bei einer derartigen Anordnung die Bahn hinter dem Preßspalt ein Stück weit an der Oberwalze haften bleibt und unter Aufwendung einer gewissen Zugspannung Von der Oberwalze abgezogen werden muß. Dabei läuft die Bahn zumindest ein kurzes Stück weit frei, d.h. ohne Stützung durch den Überführfilz. Außerdem ist es hierbei unvermeidlich, daß die Bahn, die dort noch relativ feucht ist und somit nur eine geringe Festigkeit hat, eine gewisse Längsdehnung erleidet. Diese Längsdehnung ist unerwünscht, weil sie sich auf die Qualitätseigenschaften der fertigen Bahn negativ auswirkt; z.B. resultiert daraus eine unerwünschte Quer-Kontraktion der Bahn. Erschwerend kommt hinzu, daß die erwähnte Längsdehnung ungleichmäßig über die Bahnbreite stattfindet; denn die Bahnränder werden meistens stärker gedehnt als der mittlere Bereich der Bahn. Hierdurch werden ungleichmäßige Qualitätseigenschaften der fertigen Bahn, gemessen über die Bahnbreite, erzeugt.Such an arrangement is known from EP 0346659. It has the following features in detail: The last press of the press section has only a single felt belt, namely a bottom felt, which at the same time has the function of the transfer felt. The web to be dewatered thus comes into direct contact with the top roller of the last press. This top roller therefore has a smooth and generally hard outer surface, for example formed from granite or artificial stone. It is generally known that in such an arrangement the web adheres to the top roller a little behind the press nip and with a certain tension from the top roller must be deducted. The web runs at least a short distance, ie without support from the transfer felt. In addition, it is inevitable that the web, which is still relatively damp there and therefore has only a low strength, suffers a certain longitudinal expansion. This longitudinal stretching is undesirable because it has a negative effect on the quality properties of the finished web; for example, this results in an undesirable cross-contraction of the web. To make matters worse, the aforementioned longitudinal expansion takes place unevenly over the web width; because the edges of the web are usually stretched more than the central area of the web. This creates uneven quality properties of the finished web, measured over the web width.

Ein weiteres Merkmal des genannten Vorschlages besteht darin, daß der erste Trockenzylinder der Trockenpartie innerhalb der Schlaufe des Überführfilzes angeordnet ist. Somit kommt die Bahn mit diesem ersten Trockenzylinder nicht in unmittelbaren Kontakt. Daraus resultiert - insbesondere bei hohen Arbeitsgeschwindigkeiten - die Gefahr, daß sich die Papierbahn aufgrund der Fliehkraft am ersten Trockenzylinder vom Überführfilz abhebt.Another feature of the proposal mentioned is that the first drying cylinder of the dryer section is arranged within the loop of the transfer felt. The web therefore does not come into direct contact with this first drying cylinder. This results - particularly at high working speeds - in the danger that the paper web will lift off from the transfer felt due to the centrifugal force on the first drying cylinder.

Aus der US-PS 4,648,942 ist eine Anordnung bekannt bei der die letzte Presse die folgenden Merkmale aufweist: Die Bahn läuft dort zwischen zwei Filzbändern durch den Preßspalt und von dort bis zu einer im Unterfilz angeordneten Trenneinrichtung; dort löst sich der Oberfilz von der Bahn, die mit dem Unterfilz weiterläuft, bis sie mittels des ersten Trockensiebes der Trockenpartie und mittels einer Abnahmesaugwalze in die Trockenpartie überführt wird. In der letzten Presse ist die Unterwalze als Langspalt-Presswalze ausgebildet; d.h. diese Walze hat ein flexibles, umlaufendes (schlauch- oder bandförmiges) und flüssigkeitsdichtes Preßelement, das mittels eines Preßschuhes an die Oberwalze anpreßbar ist. Ein Nachteil dieser Anordnung ist darin zu sehen, daß die Bahn sehr frühzeitig, d.h. solange sie noch relativ feucht und weich ist, mit dem relativ harten und groben Trockensieb in Berührung kommt. Hierdurch besteht die Gefahr, daß das Trockensieb bleibende Einprägungen in der Papierbahn hinterläßt. Derartige Einprägungen können vielleicht bei groben Papiersorten, die z.B. für Verpackungszwecke vorgesehen sind, hingenommen werden, nicht jedoch beispielsweise bei Druck- und Schreibpapieren. Außerdem ist das Haften der Papierbahn an der relativ groben Oberfläche nicht immer gewährleistet, besonders bei hohen Geschwindigkeiten.An arrangement is known from US Pat. No. 4,648,942 in which the last press has the following features: the web runs there between two felt belts through the press nip and from there to a separating device arranged in the bottom felt; there the upper felt detaches from the web, which continues with the lower felt, until it is transferred to the drying section by means of the first dryer fabric of the dryer section and by means of a suction suction roll. In the last press, the lower roll is designed as an extended-nip press roll; ie this roller has a flexible, rotating (tubular or band-shaped) and liquid-tight pressing element, which by means of a Press shoe is pressed onto the top roller. A disadvantage of this arrangement is that the web comes into contact with the relatively hard and coarse dryer fabric very early, ie while it is still relatively moist and soft. As a result, there is a risk that the dryer fabric leaves permanent impressions in the paper web. Such embossings may be accepted for coarse paper types, which are intended for packaging purposes, for example, but not, for example, for printing and writing papers. In addition, the adherence of the paper web to the relatively coarse surface is not always guaranteed, especially at high speeds.

Der Erfindung liegt die Aufgabe zugrunde, eine Anordnung zum Überführen einer Bahn von der Pressen- zur Trockenpartie einer Papiermaschine anzugeben, die allen nachfolgend angegebenen Forderungen gerecht wird:

  • 1. Eine Längsdehnung der Bahn soll mit Sicherheit vermieden werden; d.h. die Bahn darf sich an keiner Stelle frei (d.h. ohne Stützung durch ein mitlaufendes Band) fortbewegen. Dies gilt für die Pressenpartie, für den Bereich zwischen der Pressen- und der Trockenpartie und zumindest für den Anfangsbereich der Trockenpartie. Somit darf die Bahn in der Pressenpartie nicht in direkten Kontakt mit einer glatten und harten Walzen-Mantelfläche kommen, von der sie unter Aufwendung einer gewissen Zugspannung abgezogen werden müßte.
  • 2. Die Bahn soll erst möglichst spät mit einem Trockensieb in Kontakt kommen, um der Gefahr bleibender Einprägungen vorzubeugen.
  • 3. Die Anordnung soll insbesondere für die Herstellung feiner Papiersorten (z.B. von Druck- und/oder Schreibpapieren), darunter auch relativ dünner Papiere bei extrem hohen Geschwindigkeiten (Größenordnung 2000 m/min oder darüber) geeignet sein.
The invention is based on the object of specifying an arrangement for transferring a web from the press section to the dryer section of a paper machine which meets all of the following requirements:
  • 1. A longitudinal stretching of the web should be avoided with certainty; ie the web must not move freely at any point (ie without the support of a moving belt). This applies to the press section, for the area between the press section and the dryer section and at least for the initial area of the dryer section. Thus, the web in the press section must not come into direct contact with a smooth and hard roll surface, from which it would have to be pulled off using a certain tensile stress.
  • 2. The web should only come into contact with a dryer fabric as late as possible to prevent the risk of permanent impressions.
  • 3. The arrangement is intended in particular for the production of fine types of paper (for example printing and / or writing papers), including relatively thin papers at extremely high speeds (of the order of 2000 m / min or above).

Diese Aufgabe wird durch die kennzeichnenden Merkmale des Anspruches 1 gelöst.This object is achieved by the characterizing features of claim 1.

Das Wesentliche der Erfindung besteht in der Kombination der bisher nur einzeln bekannten Merkmale, nämlich Führen der Bahn durch die letzte Presse der Pressenpartie zwischen zwei Bändern (von denen das "erste Band" wie bisher auch die Funktion des von der Pressen- zur Trockenpartie laufenden Überführfilzes hat) und Trennen der Bahn vom "zweiten Band" mittels einer Trenneinrichtung, die derart arbeitet, daß ein freier Bahnzug vermieden wird. Hierdurch werden zwei Wirkungen gleichzeitig erreicht: Zum einen wird jegliche Längsdehnung der Papierbahn innerhalb der Pressenpartie und beim Überführen zur Trockenpartie vermieden; zum anderen wird der Überführfilz bei seinem Lauf über zumindest den ersten Trockenzylinder der Trockenpartie erwärmt, so daß er mit höherer Temperatur als bisher zur letzten Presse zurückkehrt. Hierdurch erhöht sich die Entwässerungsleistung der letzten Presse; denn der erwärmte Filz hat nunmehr einen geringeren Strömungswiderstand für das aus der Papierbahn aufzunehmende Wasser.The essence of the invention consists in the combination of the previously only individually known features, namely guiding the web through the last press of the press section between two belts (of which the "first belt" as before also functions as the transfer felt running from the press section to the dryer section has) and separating the web from the "second belt" by means of a separating device which works in such a way that a free web tension is avoided. This achieves two effects at the same time: firstly, any longitudinal stretching of the paper web within the press section and when transferring it to the dryer section is avoided; on the other hand, the transfer felt is heated as it runs over at least the first drying cylinder of the dryer section, so that it returns to the last press at a higher temperature than before. This increases the drainage capacity of the last press; because the heated felt now has a lower flow resistance for the water to be absorbed from the paper web.

Diese genannten Vorteile, nämlich Wegfall der Längsdehnung der Papierbahn und Erhöhung der Entwässerungsleistung der letzten Presse wirken nun derart zusammen, daß bei der Herstellung der oben erwähnten feinen Papiersorten (darunter auch insbesondere dünner Papiersorten) gegenüber bisher eine überdurchschnittliche Steigerung der Arbeitsgeschwindigkeit möglich wird, nämlich auf Werte um 2000 m/min oder darüber. Da ferner der Überführfilz in erster Linie als Naßfilz arbeitet und somit eine relativ feine Struktur aufweisen muß, haftet die Papierbahn in den Überführstrecken besser am Filz, insbesondere bei den geplanten hohen Arbeitsgeschwindigkeiten.These advantages mentioned, namely the elimination of the longitudinal stretching of the paper web and the increase in the dewatering capacity of the last press, now work together in such a way that an above-average increase in the working speed is possible in the manufacture of the above-mentioned fine paper types (including in particular thin paper types), namely on Values around 2000 m / min or above. Furthermore, since the transfer felt works primarily as a wet felt and must therefore have a relatively fine structure, the paper web adheres better to the felt in the transfer lines, especially at the planned high working speeds.

Im Anspruch 2 ist ein wichtiger weiterführender Gedanke der Erfindung angegeben. Danach übt der Überführfilz - zusätzlich zu den bisher schon genannten Funktionen, nämlich Wasseraufnahme im letzter Preßspalt und Überführen der Bahn in die Trockenpartie - eine dritte Funktion aus, indem er die Bahn wenigstens an den ersten Trockenzylinder der Trockenpartie anpreßt. D.h. die Anordnung ist derart getroffen, daß die Bahn stets in unmittelbaren Kontakt mit demjenigen Trockenzylinder bzw. denjenigen Trockenzylindern kommt, über den bzw. über die der Überführfilz läuft. Hierdurch wird sichergestellt, daß in der Trockenpartie das Trocknen der Bahn von Anfang an zügig einsetzt. Außerdem wird vermieden, daß an dem bzw. den genannten Trockenzylinder(n) ein zusätzliches Filz- oder Siebband erforderlich ist, um die Bahn mit dem Überführfilz in Kontakt zu halten.In claim 2 an important further idea of the invention is given. Thereafter, in addition to the functions already mentioned, namely water absorption in the last press nip and transfer of the web into the dryer section, the transfer felt performs a third function by pressing the web at least onto the first dryer cylinder of the dryer section. I.e. the arrangement is such that the web always comes into direct contact with that drying cylinder or drying cylinders over or over which the transfer felt runs. This ensures that the drying of the web starts quickly from the start. In addition, it is avoided that an additional felt or wire belt is required on the drying cylinder (s) mentioned in order to keep the web in contact with the transfer felt.

Hinzu kommt der weitere Vorteil, daß die Papierbahn im Anfangsbereich der Trockenpartie (d.h. zumindest am ersten Trockenzylinder) durch den Überführfilz an den oder die Trockenzylinder angepreßt wird. Da der Überführfilz, wie schon erwähnt, eine feine Struktur aufweist, ist im Anfangsbereich der Trockenpartie die Gefahr vermieden, daß bleibende Einprägungen in der Papierbahn hervorgerufen werden, so wie dies durch ein viel gröberes Trockensieb verursacht werden kann. Mit anderen Worten: die Erfindung ermöglicht es viel eher als bisher, feine Papiersorten mit den gewünschten hohen Qualitätseigenschaften herzustellen.In addition, there is the further advantage that the paper web in the initial area of the dryer section (ie at least on the first drying cylinder) is pressed by the transfer felt onto the drying cylinder or cylinders. Since the transfer felt, as already mentioned, has a fine structure, the risk in the initial area of the dryer section is avoided that permanent impressions are caused in the paper web, as can be caused by a much coarser dryer fabric. In other words, the invention makes it much easier than before to produce fine papers with the desired high quality properties.

Die im Anspruch 1 erwähnte und hinter dem letzten Preßspalt erforderliche Trenneinrichtung kann in recht unterschiedlicher Weise ausgeführt werden: Man kann in bekannter Weise einen Saugkasten oder eine Saugwalze vorsehen. Oder man verwendet eine erste Saugleitwalze der Trockenpartie als Trennvorrichtung. Die Anordnung einer derartigen Saugleitwalze vor dem ersten Trockenzylinder ist häufig erwünscht, um am ersten Trockenzylinder einen möglichst großen Umschlingungswinkel zu erhalten.The separating device mentioned in claim 1 and required behind the last press nip can be carried out in quite different ways: a suction box or a suction roller can be provided in a known manner. Or a first suction guide roller of the dryer section is used as a separating device. The arrangement of such a suction guide roller in front of the first drying cylinder is often desirable in order to obtain the largest possible wrap angle on the first drying cylinder.

Zur weiteren Erhöhung der Entwässerungsleistung der letzten Presse wird man diese bevorzugt als Langspalt-Presse ausbilden; d.h. eine der beiden Walzen hat - anstelle eines normalen, z.B. metallischen Walzenmantels - ein flexibles umlaufendes (schlauch- oder bandförmiges) Preßelement, das mittels einer Stützeinrichtung (vorzugsweise Preßschuh) an die andere Walze anpreßbar ist.To further increase the drainage capacity of the last press, this will preferably be designed as a long-gap press; i.e. has one of the two rollers - instead of a normal one, e.g. metallic roller shell - a flexible circumferential (tubular or band-shaped) pressing element which can be pressed onto the other roller by means of a support device (preferably a press shoe).

Der Überführfilz kann in der letzten Presse entweder die Funktion des Unterfilzes oder die Funktion des Oberfilzes übernehmen. Beide Varianten sind weiter unten im einzelnen beschrieben. Das gemäß Anspruch 1 erforderliche "zweite endlose Band" kann entweder - ähnlich wie der Überführfilz - als wasseraufnahmefähiges Filzband ausgebildet sein; oder es ist als ein elastisches Preßband mit relativ geringer Wasseraufnahmefähigkeit ausgebildet. Außerdem ist es möglich, daß das zweite Band unmittelbar das flexible (schlauch- oder bandförmige) Preßelement einer Langspalt-Presse bildet. In diesem Falle ist also in der letzten Presse nur ein einziges wasseraufnahmefähiges Filzband (nämlich der Überführfilz) vorgesehen.The transfer felt can take over either the function of the bottom felt or the function of the top felt in the last press. Both variants are described in detail below. The "second endless belt" required according to claim 1 can either - like the transfer felt - be designed as a water-absorbent felt belt; or it is designed as an elastic press belt with a relatively low water absorption capacity. In addition, it is possible that the second band directly forms the flexible (tubular or band-shaped) pressing element of an extended-gap press. In this case, only a single water-absorbent felt belt (namely the transfer felt) is provided in the last press.

Zweckmäßig wird man noch Maßnahmen ergreifen, die zur weiteren Erhöhung der Entwässerungsleistung der letzten Presse dienen, nämlich dadurch, daß man die Rückbefeuchtung der Bahn hinter dem Preßspalt so weit wie möglich reduziert. Zu diesem Zweck kann vorgesehen werden, den Überführfilz hinter dem Preßspalt ein Stück weit ohne die Bahn über eine Hilfsleitwalze und von dieser zurück zur Trenneinrichtung zu führen. Die Bahn läuft in diesem Falle hinter dem Preßspalt zunächst nur mit dem zweiten Band und wechselt dann an der Trenneinrichtung, die man als Abnahmesaugwalze ausbildet, auf den Überführfilz.Appropriately, measures will be taken which serve to further increase the drainage capacity of the last press, namely by reducing the rewetting of the web behind the press nip as far as possible. For this purpose, it can be provided to guide the transfer felt a little behind the press nip without the web over an auxiliary guide roller and from there back to the separating device. In this case, the web runs behind the press nip initially only with the second belt and then changes on the separating device, which is designed as a take-off suction roll, onto the transfer felt.

Falls die letzte Presse als Langspalt-Presse mit Preßschuh ausgebildet ist, kann man den Preßschuh gemäß DE-OS 38 15 278 derart gestalten, daß er zugleich die Funktion der Trenneinrichtung übernimmt, wobei ebenfalls die Rückbefeuchtung der Bahn reduziert wird.If the last press is designed as an extended-gap press with a press shoe, the press shoe according to DE-OS 38 15 278 can be used design in such a way that it also takes over the function of the separating device, the rewetting of the web also being reduced.

Verschiedene Ausführungsbeispiele der Erfindung werden nachfolgend anhand der Zeichnungen beschrieben.Various embodiments of the invention are described below with reference to the drawings.

Die Fig. 1 zeigt schematisch die letzte Presse und die erste Trockengruppe einer Papiermaschine.Fig. 1 shows schematically the last press and the first dryer group of a paper machine.

Die Figuren 2 und 4 bis 6 zeigen Abwandlungen der Anordnung gemäß Fig. 1.FIGS. 2 and 4 to 6 show modifications of the arrangement according to FIG. 1.

Die Fig. 3 zeigt einen Querschnitt durch den Preßschuh einer Langspalt-Presswalze (vergrößertes Detail aus Fig. 2).FIG. 3 shows a cross section through the press shoe of an extended-nip press roll (enlarged detail from FIG. 2).

Die Fig. 1 zeigt einen Ausschnitt aus einer Papierherstellungsmaschine mit einem Teil der Pressenpartie 10 und mit dem Anfangsteil einer Trockenpartie 20. In Fig. 1 erkennt man zunächst eine Doppelfilz-Presse mit einer obenliegenden Langspalt-Presswalze 14 und mit einer untenliegenden Gegenwalze 13. Von der Langspalt-Presswalze 14 sind schematisch dargestellt ein flexibler umlaufender schlauchförmiger Pressmantel 14a und ein Preßschuh 14b, mit dem der Pressmantel an die Gegenwalze anpreßbar ist. Der übliche stationäre Tragkörper, in dem der Preßschuh 14b in radialer Richtung gleiten kann, und alle übrigen Einzelheiten sind weggelassen. Der vom Pressmantel 14a und der Gegenwalze 13 gebildete verlängerte Preßspalt ist mit 19 bezeichnet. Durch diesen hindurch laufen ein Unterfilz 11, ein Oberfilz 12 und dazwischen die zu entwässernde (und danach zu trocknende) Papierbahn 9. Diese wird mittels einer im Oberfilz 12 liegenden Abnahmesaugwalze 16 von einem vorgehenden Filzband 8 abgenommen.1 shows a section of a paper-making machine with part of the press section 10 and with the beginning part of a drying section 20. In FIG. 1, a double-felt press with an upper long-nip press roll 14 and with a counter-roll 13 below is first seen the long nip press roll 14 are shown schematically, a flexible circumferential tubular press jacket 14a and a press shoe 14b with which the press jacket can be pressed against the counter roll. The usual stationary support body in which the press shoe 14b can slide in the radial direction and all other details are omitted. The extended press nip formed by the press jacket 14a and the counter roll 13 is designated by 19. A bottom felt 11, an upper felt 12 and the paper web 9 to be dewatered (and then dried) run through it. This is removed from a preceding felt belt 8 by means of a take-off suction roller 16 located in the upper felt 12.

Die beiden Filzbänder 11 und 12 sind in der Regel wie üblich als wasseraufnahmefähige Naßfilze ausgebildet. Alternativ hierzu kann anstelle des Oberfilzes 12 ein flexibles Preßband vorgesehen werden, dessen Wasseraufnahmefähigkeit geringer ist als diejenige des Unterfilzes 11. Der Unterfilz 11 dient zugleich als Überführfilz; d.h. er überführt die Papierbahn 9 von der Pressenpartie 10 in die Trockenpartie 20. Wesentlich ist, daß der Überführfilz 11 zugleich zum Anpressen der Papierbahn 9 an wenigstens den ersten Trockenzylinder 21, vorzugsweise an eine Gruppe von beispielsweise vier Trockenzylindern 21 und 22 dient. Deshalb liegen alle diese Trockenzylinder 21, 22 außerhalb der endlosen Schlaufe des Überführfilzes 11.The two felt belts 11 and 12 are usually designed as usual as water-absorbent wet felts. Alternatively, a flexible press belt can be provided instead of the upper felt 12, the water absorption capacity of which is less than that of the lower felt 11. The lower felt 11 also serves as a transfer felt; i.e. it transfers the paper web 9 from the press section 10 into the drying section 20. It is essential that the transfer felt 11 also serves to press the paper web 9 onto at least the first drying cylinder 21, preferably onto a group of, for example, four drying cylinders 21 and 22. Therefore, all of these drying cylinders 21, 22 lie outside the endless loop of the transfer felt 11.

Hinter dem Preßspalt 19 können zunächst beide Filzbänder 11 und 12 (zusammen mit der dazwischen liegenden Papierbahn) gemeinsam bis zu einer Trenneinrichtung 17 laufen. Diese liegt in Fig. 1 in der Schlaufe des Überführfilzes 11 und ist als Saugwalze ausgebildet mit einer Abnahme-Saugzone 17a, so daß von hier ab die Papierbahn 9 zusammen mit dem Überführfilz 11 läuft. Eine Alternative ist in Figur 1 mit strichpunktierten Linien dargestellt: Der Überführfilz 11 wird hinter dem Preßspalt 19 ohne die Bahn 9 über eine Hilfsleitwalze 42 umgeleitet und läuft dann zurück zur Trenneinrichtung 17. Im Bereich dieser Umleitung wird der Überführfilz 11 konditioniert, beispielsweise dadurch, daß die als Saugwalze ausgebildete Trenneinrichtung 17 eine Konditionier-Saugzone 17b aufweist. Alternativ oder zusätzlich hierzu kann die Hilfsleitwalze 42 als Saugwalze oder als Blaswalze ausgebildet sein; oder es wird ein Rohrsauger vorgesehen (Fig. 4 Ziffer 43).Behind the press nip 19, both felt belts 11 and 12 (together with the paper web in between) can run together to a separating device 17. This is in Fig. 1 in the loop of the transfer felt 11 and is designed as a suction roll with a removal suction zone 17a, so that from here the paper web 9 runs together with the transfer felt 11. An alternative is shown in FIG. 1 with dash-dotted lines: the transfer felt 11 is diverted behind the press nip 19 without the web 9 via an auxiliary guide roller 42 and then runs back to the separating device 17. In the area of this diversion, the transfer felt 11 is conditioned, for example by the fact that the separating device 17 designed as a suction roll has a conditioning suction zone 17b. Alternatively or in addition to this, the auxiliary guide roller 42 can be designed as a suction roller or as a blowing roller; or a pipe suction device is provided (Fig. 4, number 43).

Vor dem ersten Trockenzylinder 21 läuft der Überführfilz 11 zusammen mit der Papierbahn 9 über eine Leitwalze 23. Außerdem ist hinter jedem der Trockenzylinder 21, 22 eine Leitwalze 24, 25 vorgesehen. Diese Leitwalzen liegen alle innerhalb der Schlaufe des Überführfilzes 11, so daß sich die Papierbahn 9 im Bereich der Leitwalzen an der Außenseite des Überführfilzes befindet und deshalb einer gewissen Fliehkraft ausgesetzt ist. Um der Fliehkraft entgegenzuwirken, sind die Leitwalzen 23, 24, 25 in bekannter Weise als Saugwalzen ausgebildet. Von der letzten Saugleitwalze 25 läuft der Überführfilz 11 über eine verstellbare Leitwalze 26 und über weitere Leitwalze 27 zurück zur Leitwalze 15 der Pressenpartie 10. Zwischen den Leitwalzen 25 und 26 wird die Papierbahn 9 mit Hilfe eines weiteren Filzbandes oder Trockensiebes 28 und mit Hilfe einer Abnahmesaugwalze 29 vom Überführfilz 11 abgenommen und einer nachfolgenden nicht dargestellten Trocknungsstation zugeführt.In front of the first drying cylinder 21, the transfer felt 11 runs together with the paper web 9 over a guide roller 23. In addition, a guide roller 24, 25 is provided behind each of the drying cylinders 21, 22. These guide rollers are all located within the loop of the transfer felt 11, so that the paper web 9 is in the area of the guide rollers on the outside of the transfer felt and is therefore subject to a certain centrifugal force. In order to counteract the centrifugal force, the guide rollers 23, 24, 25 are designed in a known manner as suction rollers. From the last suction guide roll 25, the transfer felt 11 runs over an adjustable guide roll 26 and over further guide roll 27 back to the guide roll 15 of the press section 10. Between the guide rolls 25 and 26, the paper web 9 is fed with the help of a further felt belt or dryer fabric 28 and with the help of a take-off suction roll 29 removed from the transfer felt 11 and fed to a subsequent drying station, not shown.

In Fig. 1 bilden die Trockenzylinder 21 und 22 eine im wesentlichen vertikale Zylinder-Reihe. Statt dessen könnten die Trockenzylinder aber auch in einer im wesentlichen horizontalen Reihe angeordnet werden.In Fig. 1, the drying cylinders 21 and 22 form an essentially vertical row of cylinders. Instead, the drying cylinders could also be arranged in an essentially horizontal row.

In Fig. 2 ist, abweichend von Fig. 1 die Langspalt-Preßwalze 14 unterhalb der Gegenwalze 13 angeordnet. Ein weiterer Unterschied zur Fig. 1 besteht darin, daß zum Trennen des Oberfilzes 12 von der Papierbahn 9 und vom Überführfilz 11 nicht eine spezielle Trenneinrichtung (wie in Fig. 1, Ziff. 17) vorgesehen ist. Dargestellt sind zwei andere Varianten. Gemäß der in vollen Linien dargestellten ersten Variante laufen beide Filzbänder 11 und 12 zusammen mit der dazwischen liegenden Papierbahn gemeinsam bis zur ersten Saugleitwalze 23a. Diese kann bei Bedarf eine Vorsaugzone 23b haben, die vor der Stelle liegt, wo die beiden Filze auf die Saugleitwalze auflaufen. Der Oberfilz läuft sodann über eine Leitwalze 18a und die weiteren Leitwalzen 18 zurück zur Abnahmesaugwalze 16.In FIG. 2, in contrast to FIG. 1, the long nip press roll 14 is arranged below the counter roll 13. Another difference from FIG. 1 is that a special separating device (as in FIG. 1, item 17) is not provided for separating the upper felt 12 from the paper web 9 and from the transfer felt 11. Two other variants are shown. According to the first variant shown in full lines, both felt belts 11 and 12 run together with the paper web in between up to the first suction guide roller 23a. If necessary, this can have a pre-suction zone 23b, which lies in front of the point where the two felts run onto the suction guide roller. The top felt then runs over a guide roller 18a and the further guide rollers 18 back to the take-off suction roller 16.

Gemäß einer zweiten, mit Strich-Doppelpunkt-Linien dargestellten Variante trennen sich die beiden Filzbänder 11 und 12 kurz hinter dem Auslauf aus dem verlängerten Preßspalt 19. Dies wird angestrebt, um hinter dem Preßspalt 19 die Rückbefeuchtung der Papierbahn aus dem Oberfilz 12 so weit wie möglich zu reduzieren. Um dies zu erreichen, ist am Preßschuh 14b gemäß Fig. 3 folgendes vorgesehen (wie an sich bekannt aus der DE-OS 38 08 293): Der Preßschuh 14a ist unterteilt in ein Oberteil 34 und ein als Kolben wirkendes Unterteil 35. Letzteres ist in einer Druckkammer 32 angeordnet; dies ist eine Ausnehmung des feststehenden Tragkörpers 31. Zur Führung des Preßschuhes und zur Abdichtung der Druckkammer 32 dienen Dichtleisten und dazugehörende Dichtleistenträger 38 und 39. Der mittlere Teil der Gleitfläche 33 des Preßschuh-Oberteils 34 bildet die konkav geformte Anpreßfläche mit der Breite b. In Laufrichtung hinter der Anpreßfläche hat das Preßschuh-Oberteil 34 eine konvex gekrümmte Führungsfläche 36. Deren Krümmungsradius K kann ungefähr gleich dem Radius R der Umlaufbahn des Pressmantels 14a sein. Vom Auslauf-Ende A des Preßspaltes laufen die beiden Filzbänder 11 und 12 (dazwischen die Papierbahn 9) und der Pressmantel 14a zunächst über die Führungsfläche 36. Erst an der Stelle B, also kurz vor dem auslaufseitigen Ende des Preßschuh-Oberteiles 34, hebt sich der Oberfilz 12 von der Papierbahn 9 ab und läuft von hier zu der Leitwalze 18a' (Fig. 2). Zwischen den Stellen A und B kann Luft in den Oberfilz 12 eintreten, so daß sich die Papierbahn 9 an der Stelle B sicher vom Oberfilz 12 löst und mit dem Unterfilz (Überführfilz 11) mitläuft (in Richtung zur Saugleitwalze 23a, Fig. 2). Die Breite der Führungsfläche 36 (in Bahnlaufrichtung) ist mit d bezeichnet.According to a second variant, shown with dash-and-dot lines, the two felt belts 11 and 12 separate shortly behind the outlet from the extended press nip 19. This is aimed at to rewet the press nip 19 behind the press nip Reduce paper web from the top felt 12 as much as possible. In order to achieve this, the following is provided on the press shoe 14b according to FIG. 3 (as known per se from DE-OS 38 08 293): The press shoe 14a is divided into an upper part 34 and a lower part 35 acting as a piston. The latter is shown in FIG a pressure chamber 32 arranged; This is a recess of the fixed support body 31. Sealing strips and associated sealing strip supports 38 and 39 are used to guide the press shoe and to seal the pressure chamber 32. The middle part of the sliding surface 33 of the press shoe upper part 34 forms the concave-shaped contact surface with the width b. In the running direction behind the contact surface, the press shoe upper 34 has a convexly curved guide surface 36. The radius of curvature K thereof can be approximately equal to the radius R of the orbit of the press cover 14a. From the outlet end A of the press nip, the two felt belts 11 and 12 (in between the paper web 9) and the press jacket 14a initially run over the guide surface 36. Only at point B, that is to say shortly before the outlet-side end of the press shoe upper part 34, does it rise the upper felt 12 from the paper web 9 and runs from here to the guide roller 18a '(Fig. 2). Air can enter the upper felt 12 between the positions A and B, so that the paper web 9 safely detaches from the upper felt 12 at the point B and moves with the lower felt (transfer felt 11) (in the direction of the suction guide roller 23a, FIG. 2). The width of the guide surface 36 (in the direction of web travel) is designated by d.

Die Fig. 4 unterscheidet sich von Fig. 1 dadurch, daß in der Presse kein Oberfilz vorhanden ist. In diesem Falle übernimmt also der schlauchförmige Preßmantel 14a der Langspalt-Preßwalze 14 die Funktion des (gem. Anspruch 1 vorgesehenen) zweiten Bandes. Der nicht-rotierende (radial verschiebbare) Preßschuh 14b kann ersetzt werden durch einen drehbaren Walzenkörper 46, wie strichpunktiert angedeutet. Der Überführfilz 11 wird hinter dem Preßspalt 19 ohne die Bahn 9 umgeleitet, nämlich vorbei an einem Rohrsauger 43 und über eine Hilfsleitwalze 42 und schließlich zurück zu der als Saugwalze ausgebildeten Trenneinrichtung 17. Diese ist derart angeordnet, daß der aufblasbare Preßmantel 14a an der Saugwalze 17 eine kleine Umschlingungszone bildet. Hierdurch wird ein sicheres Überwechseln der Bahn 9 vom Preßmantel 14a auf den Überführfilz 11 sichergestellt. Vor dem Preßspalt 19 ist in der Schlaufe des Überführfilzes 11 eine Abnahmesaugwalze 15' vorgesehen, die sicherstellt, daß die Bahn 9 von dem vorangehenden Filzband 8 auf den Überführfilz 11 überwechselt.Fig. 4 differs from Fig. 1 in that there is no top felt in the press. In this case, the tubular press jacket 14a of the extended-nip press roll 14 assumes the function of the second belt (provided according to claim 1). The non-rotating (radially displaceable) press shoe 14b can be replaced by a rotatable roller body 46, as indicated by dash-dotted lines. The transfer felt 11 is diverted behind the press nip 19 without the web 9, namely past a pipe suction device 43 and via an auxiliary guide roller 42 and finally back to the one designed as a suction roller Separating device 17. This is arranged such that the inflatable press jacket 14a forms a small looping zone on the suction roll 17. This ensures a secure transfer of the web 9 from the press jacket 14a to the transfer felt 11. In front of the press nip 19, a take-off suction roll 15 'is provided in the loop of the transfer felt 11, which ensures that the web 9 changes from the preceding felt belt 8 to the transfer felt 11.

Gemäß den Fig. 1 bis 4 hat der Unterfilz 11 der letzten Presse 13, 14 die Funktion des Überführfilzes. In Fig. 5 dagegen ist die Anordnung derart getroffen, daß der Oberfilz 11' die Funktion des Überführfilzes hat, wobei die Oberwalze als Langspalt-Presswalze 14 ausgebildet ist. Der Unterfilz ist mit 12' bezeichnet. Der Preßschuh 14b kann wiederum entsprechend der Fig. 3 ausgebildet sein, so daß sich die beiden Filzbänder 11' und 12' am auslaufseitigen Ende des Preßschuhes trennen. Der Oberfilz 11' führt die Papierbahn 9 wiederum zunächst über eine erste Saugleitwalze 23 und danach abwechselnd über Trockenzylinder 21, 22 und weitere Saugleitwalzen 24 und 25. Schematisch sind Schaber 40 angedeutet, die am freien Teil der Zylinder-Oberflächen anliegen. Derartige Schaber sind auch bei der Bauweise gemäß den Fig. 1, 2 und 4 vorhanden, aber in der Zeichnung weggelassen. In Fig. 5 sind außerdem Heißluft-Blaskästen 41 angedeutet, die an den Saugleitwalzen 24 Heißluft auf die Papierbahn blasen und die zusätzlich Abluft absaugen können.1 to 4, the bottom felt 11 of the last press 13, 14 has the function of the transfer felt. 5, on the other hand, the arrangement is such that the top felt 11 'has the function of the transfer felt, the top roller being designed as an extended-nip press roller 14. The bottom felt is designated 12 '. The press shoe 14b can in turn be designed according to FIG. 3, so that the two felt belts 11 'and 12' separate at the outlet end of the press shoe. The upper felt 11 'in turn guides the paper web 9 first over a first suction guide roller 23 and then alternately over drying cylinders 21, 22 and further suction guide rollers 24 and 25. Schematically, scrapers 40 are indicated, which rest on the free part of the cylinder surfaces. Such scrapers are also present in the construction according to FIGS. 1, 2 and 4, but are omitted in the drawing. In FIG. 5, hot air blow boxes 41 are also indicated, which blow hot air onto the paper web at the suction guide rollers 24 and which can additionally extract exhaust air.

Bei der Anordnung gem. Fig. 5 kann eventuell anfallender Ausschuß (beim Abriß der Papierbahn) auf der der Pressenpartie zugewandten Seite der Zylinder-Reihe 21, 22 unbehindert nach unten fallen. Dagegen muß in den Fig. 1, 2 und 4 eventuell anfallender Ausschuß auf der anderen Seite der Zylinder-Reihe 21, 22 nach unten abgeführt werden. Hierzu muß die verstellbare Leitwalze 26 gemäß Fig. 1 in die mit strichpunktierten Linien dargestellte Position gebracht werden, so daß der Ausschuß zwischen den Saugleitwalzen 25 und 29 nach unten fallen kann.With the arrangement acc. Fig. 5 can possibly incurred waste (when tearing off the paper web) on the press side facing the cylinder row 21, 22 down unhindered. In contrast, in Fig. 1, 2 and 4 possibly incurred committee on the other side of the cylinder row 21, 22 must be carried down. The adjustable Guide roller 26 as shown in FIG. 1 are brought into the position shown with dash-dotted lines, so that the reject between the suction guide rollers 25 and 29 can fall down.

Die Fig. 6 unterscheidet sich von der Fig. 5 nur dadurch, daß - ähnlich wie in Fig. 2 - die Unterwalze als Langspalt-Preßwalze 14 ausgebildet ist. Hinter dem Preßspalt wird der Überführfilz (Oberfilz 11') ohne die Bahn 9 über zwei Hilfsleitwalzen 44 und 45 zu einer als Abnahme-Saugwalze ausgebildeten Trenneinrichtung 17' geführt. Die oben schon erwähnten Filz-Konditioniereinrichtungen sind in Fig. 6 nicht dargestellt.Fig. 6 differs from Fig. 5 only in that - similar to Fig. 2 - the lower roll is designed as an extended-nip press roll 14. Behind the press nip, the transfer felt (top felt 11 ') without the web 9 is guided via two auxiliary guide rollers 44 and 45 to a separating device 17' designed as a take-off suction roller. The felt conditioning devices already mentioned above are not shown in FIG. 6.

Claims (12)

  1. Arrangement for transferring a web, preferably paper web from the press end section (10) to the drying section (20) of a paper-making machine, wherein a first endless belt (11), which is constructed as a felt belt able to absorb water (referred to hereafter as the "transfer felt") together with the web (9) travels not solely through the last pressing gap (19) of the press end section, but also over at least the first drying cylinder (21) of the drying section, characterised by the following features:
    a) a second endless belt (12 or 12' or 14a) travels - as known per se - in addition to the first belt (11) through the last pressing gap (19) of the press end section (10), so that at this point the web (9) is located between the two belts (11, 12);
    b) behind the said last pressing gap (19), the transfer felt (11), together with the web (9) and the second belt (12) travels over a separating device (17 or 36) known per se, on which the second belt (12) separates from the web (9).
  2. Arrangement according to Claim 1, characterised in that the drying cylinder or cylinders (21, 22), over which the transfer felt (11) travels together with the web (9), lies/lie outside the endless loop of the transfer felt (11).
  3. Arrangement according to Claim 2, characterised in that immediately before the first drying cylinder (21), the transfer felt (11) together with the web (9) travels over a guide roller (preferably suction guide roller 23), which is located within the loop of the endless transfer felt (11).
  4. Arrangement according to Claim 3, characterised in that the guide roller (preferably suction guide roller 23) is located between the separating device (17 or 36) and the first drying cylinder (21).
  5. Arrangement according to Claim 3, characterised in that the suction guide roller (23a) simultaneously forms the separating device.
  6. Arrangement according to one of Claims 1 to 5, characterised in that the transfer felt (11) travels over the lower pressing roller (13 or 14) of the last press.
  7. Arrangement according to one of Claims 1 to 5, characterised in that the transfer felt (11) travels over the upper pressing roller (14) of the last press.
  8. Arrangement according to one of Claims 1 to 7, characterised in that the second belt (12 or 12') is constructed as a felt belt able to absorb water.
  9. Arrangement according to one of Claims 1 to 7, characterised in that the second belt (12 or 12') is constructed as an elastic pressing belt, whereof the capacity to absorb water is less than that of the transfer felt.
  10. Arrangement according to one of Claims 1 to 7, characterised in that the second belt (14a) is a flexible, tubular and liquid-tight pressing casing, which can be pressed by means of a support device (press shoe 14b or roll body 46) against a counter-roller.
  11. Arrangement according to one of the preceding Claims, characterised by the following features:
    a) behind the first pressing gap (19), the transfer felt (11) travels without the web (9) over at least one auxiliary guide roller (42) and from the latter back to the separating device (17), which is constructed as a removal suction roller lying within the endless loop of the transfer felt (11) and comes into contact with the second belt (12 or 14a), in order to separate the web (9) from the latter;
    b) a felt-conditioning device (17b; 43) is provided on the path of the transfer felt (11) free from the web (9).
  12. Arrangement according to one of Claims 1 to 10, characterised by the following features:
    a) the last pressing gap (19) of the press end section (10) is formed by a long gap pressing roller (14) with a flexible, peripheral (tubular or belt-shaped) pressing member (14a), which can be pressed by means of a press shoe (14b) against a counter-roller (13);
    b) in the direction of travel of the web behind the pressing gap (19), the press shoe (14b) has a guide surface (40) of substantially convex curvature, over which the flexible pressing member (14a) travels in contact with the transfer felt (11);
    c) the second belt (12) constructed as a felt belt is guided behind the pressing gap (19) so that it travels first of all together with the web (9) and with the transfer felt (11) over part of the guide surface (40) having a convex curvature and then separates from the web (9) (in the region of the guide surface at the outlet side, at the point B).
EP91901763A 1990-02-13 1991-01-15 Arrangement for guiding a web from the press part to the dryer part of a papermaking machine Expired - Lifetime EP0468005B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4004331A DE4004331C1 (en) 1990-02-13 1990-02-13
DE4004331 1990-02-13
PCT/EP1991/000049 WO1991012370A1 (en) 1990-02-13 1991-01-15 Arrangement for guiding a web from the press part to the dryer part of a papermaking machine

Publications (2)

Publication Number Publication Date
EP0468005A1 EP0468005A1 (en) 1992-01-29
EP0468005B1 true EP0468005B1 (en) 1994-09-07

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP91901763A Expired - Lifetime EP0468005B1 (en) 1990-02-13 1991-01-15 Arrangement for guiding a web from the press part to the dryer part of a papermaking machine

Country Status (7)

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US (1) US5169501A (en)
EP (1) EP0468005B1 (en)
JP (1) JPH04506549A (en)
AT (1) ATE111169T1 (en)
CA (1) CA2050894A1 (en)
DE (2) DE4004331C1 (en)
WO (1) WO1991012370A1 (en)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5507104A (en) 1987-02-13 1996-04-16 Beloit Technologies, Inc. Web drying apparatus
US6049999A (en) 1987-02-13 2000-04-18 Beloit Technologies, Inc. Machine and process for the restrained drying of a paper web
US5404653A (en) 1987-02-13 1995-04-11 Beloit Technologies, Inc. Apparatus for drying a web
FI98844C (en) * 1991-12-23 1997-08-25 Valmet Paper Machinery Inc Press section in paper machine, especially for printing paper grades
US5639351A (en) 1991-12-23 1997-06-17 Valmet Corporation Press section of a paper machine, in particular for printing paper qualities
DE4407405C2 (en) * 1994-03-05 2000-03-16 Voith Sulzer Papiermasch Gmbh Dryer section
FI110440B (en) * 1996-04-04 2003-01-31 Metso Paper Inc Transferring the web from the last press nip in the paper machine to the next drying section
FI106806B (en) * 1997-05-30 2001-04-12 Metso Paper Inc A drying portion of a paper machine or cardboard machine and a method of transferring the web to the drying portion of the paper machine / board machine
DE19744341A1 (en) 1997-10-07 1999-04-15 Voith Sulzer Papiertech Patent Paper machine
DE69922041T2 (en) * 1998-08-04 2005-10-13 Metso Paper, Inc. METHOD AND DEVICE FOR TREATING PAPER OR PAPER WEBSTS
DE19955029A1 (en) * 1999-11-16 2001-05-17 Voith Paper Patent Gmbh Shoe press unit at a web press station has the web passed through the press gap with flanking blankets and a structured angled path away from the press gap to prevent return of extracted water back into the web
EP3194654B1 (en) * 2014-09-15 2021-11-10 UPM Specialty Papers Oy Process to manufacture low weight high quality paper for use as a support layer of a release liner with a belt assembly

Family Cites Families (10)

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Publication number Priority date Publication date Assignee Title
US1868617A (en) * 1929-08-17 1932-07-26 John D Tompkins Method of and apparatus for making paper
US3250019A (en) * 1962-09-10 1966-05-10 Edward D Beachler Dryer felt
US3981084A (en) * 1972-06-19 1976-09-21 Fort Howard Paper Company Closed draw transfer system with gaseous pressure direction of web
DE2323574C3 (en) * 1973-05-10 1976-01-08 J.M. Voith Gmbh, 7920 Heidenheim Drying section for paper machines
FI770542A (en) * 1977-02-18 1978-08-19 Valkama P J PRESS RELEASE FOR THE CONSTRUCTION OF VAT ON FIBER BAN
US4483745A (en) * 1982-09-29 1984-11-20 Beloit Corporation Method and apparatus of sheet transfer using a nonporous smooth surfaced belt
DE3328162C2 (en) * 1983-08-04 1986-02-20 J.M. Voith Gmbh, 7920 Heidenheim Paper machine
US4561939A (en) * 1984-03-26 1985-12-31 Beloit Corporation Extended nip press arrangement
FI850087L (en) * 1985-01-08 1986-07-09 Valmet Oy FOERFARANDE OCH ANORDNING SAMT REMKOMPONENT FOER UTJAEMNING AV PRESSTRYCKET I PRESSNYPET AV EN PAPPERSMASKIN.
DE68908287T2 (en) * 1988-06-13 1993-11-25 Appleton Mills Appleton Paper machine in which the paper web is supported in the zone between the press and dryer sections.

Also Published As

Publication number Publication date
EP0468005A1 (en) 1992-01-29
ATE111169T1 (en) 1994-09-15
DE4004331C1 (en) 1991-04-18
JPH04506549A (en) 1992-11-12
DE59102820D1 (en) 1994-10-13
US5169501A (en) 1992-12-08
CA2050894A1 (en) 1991-08-14
WO1991012370A1 (en) 1991-08-22

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