EP1816256B1 - Machine and method for the manufacture of a fibrous web - Google Patents

Machine and method for the manufacture of a fibrous web Download PDF

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Publication number
EP1816256B1
EP1816256B1 EP07106782A EP07106782A EP1816256B1 EP 1816256 B1 EP1816256 B1 EP 1816256B1 EP 07106782 A EP07106782 A EP 07106782A EP 07106782 A EP07106782 A EP 07106782A EP 1816256 B1 EP1816256 B1 EP 1816256B1
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EP
European Patent Office
Prior art keywords
press
fibrous web
web
shoe
approximately
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Expired - Lifetime
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EP07106782A
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German (de)
French (fr)
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EP1816256A1 (en
Inventor
Thomas Scherb
Harald Schmidt-Hebbel
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Voith Patent GmbH
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Voith Patent GmbH
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Publication of EP1816256A1 publication Critical patent/EP1816256A1/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
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/0281—Wet presses in combination with a dryer roll

Definitions

  • the invention relates to a machine for producing a fibrous web, in particular tissue or tissue paper web, with at least one press nip formed between a shoe press unit and a dryer or tissue cylinder, through which a water-absorbing carrier tape, a water-impermeable press belt and the fibrous web are passed. It further relates to a method for producing a fibrous web.
  • the main press as viewed in the direction of web travel, comprises a drying cylinder and an associated pressing element.
  • a pressing element may be provided a suction press roll or a shoe press roll.
  • the rear main press is formed by a shoe press unit and a drying cylinder.
  • a method of hot pressing and drying a fibrous web which comprises a first step in which the fibrous web is subjected to a relatively long pressing time at a relatively low pressing pressure (first nip), a second step in which the pressing pressure is lowered significantly, and a third step in which a rapid increase in pressure is carried out.
  • first nip relatively low pressing pressure
  • second step in which the pressing pressure is lowered significantly
  • third step in which a rapid increase in pressure is carried out.
  • two press nip passages with different lengths and pressing forces are thus provided.
  • the aim of the invention is to provide a machine and a method of the type mentioned, with which the highest possible dry content and / or specific volume can be achieved while avoiding the disadvantages mentioned above and while largely adhering to the quality characteristics required for the produced web.
  • the residence time of the web in an extended press nip is less than 12 ms.
  • this object is achieved according to the invention by providing at least one press nip formed between a shoe press unit and the dryer or tissue cylinder whose length considered in the web running direction is greater than a value of about 80 mm and preferably less than 200 mm, in particular at most 150 mm, so that the fibrous web to be dewatered is subjected to a pressing pressure in the press nip (12) for a period of at least 3.5 ms and its pressure profile resulting from the press nip length has a maximum compacting pressure which is less than or equal to a value of is about 2 MPa, wherein the carrier tape and the fibrous web are guided in the web running direction in front of the drying cylinder via at least one suction device.
  • the specific volume is also slightly increased. Such an increase may be for example about 5%.
  • dry content which is particularly true in comparison to a press nip, which is formed by means of a suction press roll or by a shoe press with a gap length of, for example, 120 mm.
  • an increase in dry content of about 2.5 to 3% is possible, assuming a constant line force of about 90 kN / m.
  • a constant line force of about 90 kN / m Such a value must not be exceeded in the usual Yankee cylinders in view of a maximum allowable mechanical stress.
  • the invention can therefore be used with particular advantage especially in conversions of existing presses.
  • dry content increases as well as constant or higher values of the specific volume (bulk) can be achieved in comparison to conventional presses.
  • the residence time of the fibrous web in the press nip is in particular greater than or equal to 4 ms.
  • the residence time can be defined in particular by the ratio of gap or shoe length to the web speed.
  • the maximum line force generated by the press nip may be in the range of about 90 to about 120 kN / m.
  • the shoe press unit comprises a press shoe, which can be pressed against the drying cylinder via a plurality of contact elements arranged side by side transversely to the web running direction.
  • a respective desired pressing force transverse profile can be adjusted to even out the web properties, in particular at the web edges.
  • a creping cylinder i. a so-called Yankee cylinder may be provided.
  • the pressure profile resulting over the press nip length is preferably asymmetrical.
  • the maximum pressing pressure is preferably in the rear quarter of the press nip length viewed in the web running direction.
  • the average pressure rise gradient in the section of the pressure profile reaching from the gap beginning to the maximum pressing pressure at a new carrier strip is greater than or equal to a value of about 40 kPa / mm, in particular greater than or equal to about 60 kPa / mm and preferably greater or equal to about 120 kPa / mm.
  • the mean pressure drop gradient in the end region of the pressure profile is preferably greater than or equal to a value of about 300 kPa / mm, in particular greater than or equal to about 500 kPa / mm, and preferably greater than or equal to about 800 kPa / mm in a new carrier tape.
  • the mean pressure drop gradient in the end region increases with increasing operating time of the felt. As a result, values of more than 1000 to more than 1600 kPa / m are achieved in a press nip according to the invention.
  • the water-absorbing carrier tape lies in the press nip between the water-impermeable press belt and the fibrous web, the fibrous web contacting the drying cylinder.
  • a water-absorbing carrier tape may be provided in particular a felt.
  • a felt may, for example, have a basis weight which is less than or equal to a value of about 1450 g / m 2 .
  • It is, for example, a specially structured felt in the manner of a bumped embossing screen or felt, ie a so-called “imprinting fabric” or “imprinting felt” (see, for example, US Pat WO98 / 00604 ) or a roughly textured surface having "patterning fabric” or “patterning felt” usable.
  • the special carrier tapes in particular in combination with a press nip according to the invention having a press nip length greater than or equal to about 80 mm, have an advantageous effect on the specific volume of the paper web produced.
  • the water-absorbing carrier tape may have a different texture in the thickness direction.
  • the fibrous web facing side of the carrier tape for example, have a finer structure than its side facing away from the fibrous web page.
  • the press belt has a grooved and / or provided with blind holes surface, as for example in the DE-A-196 54 198 is described.
  • a further press nip can also be formed on the drying cylinder. It may be useful in certain applications, if at least two press gaps formed by a respective shoe press unit are provided on the drying cylinder. In principle, it is also conceivable to provide an additional press nip in the web running direction in front of the drying cylinder.
  • the at least one suction device or suction box may be provided which comprises a suction roll and / or a suction shoe.
  • a shoe press roll is provided as the shoe press unit.
  • the shoe press unit comprises at least one exchangeable press shoe.
  • the method according to the invention is characterized in that the fibrous web to be dewatered is subjected to a pressing pressure of at most 2 MPa for a period of at least 3.5 ms in the press nip whose length (L) considered in the web erection is greater than a value of about 80 mm is.
  • the invention is applicable to, for example, a crescent former, a four-wire tissue paper machine, a twin-wire former, a suction breast roll machine, etc.
  • the substance input for the production of, for example, a tissue web can consist, for example, of "refined pulp".
  • the inventive press nip can be used particularly advantageous for dry content increase.
  • such a fabric feed serving, for example, for producing a tissue web may also consist of unground material.
  • the inventive long press nip can be used particularly advantageously for increasing the specific volume.
  • the invention is also applicable for example for so-called "curled fibers".
  • the stock suspension in this case contains a proportion of fibers which have been subjected to a special treatment.
  • the substantially linear or curved in a plane pulp fibers are curved so that a spatial fiber shape, for example, arises in the manner of a spiral.
  • the invention can also be used in particular in a tissue paper machine with at least one so-called "through-air-drying" drying process, wherein the press nip according to the invention is used in particular before a corresponding "through-air-drying" device.
  • Such a combination is particularly advantageous in terms of a high dry content and a high specific volume.
  • a high dry content is achieved by the press nip according to the invention, whereby the operating costs of the energy-intensive drying phase are reduced.
  • the web is at most slightly compacted, which means that the specific volume of the web is increased or remains unimpaired at higher pressing pressures, which also makes the "through-air-drying" drying process more efficient and economical.
  • the invention is also applicable to the manufacture of multilayer webs using a single headbox or the manufacture of multilayer webs using multiple headboxes.
  • FIG. 1 shows a purely schematic partial representation of an embodiment of an inventive shoe press 10, which can be used for example in a machine for producing a fibrous web such as in particular a tissue or tissue paper web.
  • the press nip 12 of this shoe press 10 is formed between a shoe press unit, in the present case a shoe press roll 14, and a drying cylinder 16, through which except the fibrous web, a water-absorbing carrier tape 18 and a water-impervious press belt is passed, which is in the present case to the press cover 20 of the shoe press roll 14.
  • the water-absorbing carrier tape 18 may be formed in particular by a felt. In the present case, the water-absorbing carrier tape 18 is guided between the press cover 20 and the fibrous web through the press nip 12, wherein the fibrous web contacts the drying cylinder 16.
  • the shoe press roll 14 has a two-part press shoe 22, between the two parts of a thermal insulation layer 24 is inserted.
  • the press shoe 22 can be pressed against the drying cylinder 16 via a plurality of pressing elements 26 arranged juxtaposed transversely to the web running direction 1.
  • the drying cylinder 16 may be, for example, a Yankee cylinder.
  • the water-absorbing carrier tape 18 formed for example by a felt may have a different texture in the thickness direction.
  • the fibrous web facing side of the carrier tape 18 have a finer structure than its side facing away from the fibrous web page.
  • the press cover 20 may have a smooth, grooved and / or blind-bore surface.
  • press nip may be formed on the drying cylinder 16. In the web running direction 1 in front of the drying cylinder 16, an additional press nip can be provided.
  • the carrier tape 18 and the fibrous web in the web running direction 1 in front of the drying cylinder 16 can also be guided via at least one suction device.
  • the shoe press unit 14 may include at least one replaceable press shoe 22.
  • FIG. 2 the pressure profile or the pressure profile p (L) of a conventional shoe press is shown.
  • the pressing pressure p over the length L of the press nip 12 and the press shoe 22 is applied.
  • the shoe press 10 according to the invention can now be designed in particular such that the length L of the press nip 12 considered in the web running direction I (cf. FIG. 1 ) is less than or equal to a value of about 60 mm and whose over the press nip length L resulting pressure profile p (L) has a maximum pressing pressure p max , which is greater than or equal to a value of about 3.3 MPa.
  • FIG. 3 shows a comparison of the pressing pressure curve p 10 (L) of an exemplary embodiment of such a shoe press 10 according to the invention with a relatively long press shoe 12 with the pressing pressure curve p s (L) provided with a suction press conventional press.
  • the corresponding pressing pressure curve p 10 (L) has a significantly lower maximum pressing pressure p max (compare the shaded lower pressing pressure curve p 10 (for the maximum line force of 90 kN / m). L)).
  • the maximum pressing pressure p max even at a substantially higher maximum line force of 270 kN / m, is not higher than the maximum pressing pressure p max of the conventional press, for which in the present case a maximum line force of 90 kN / m is specified.
  • FIG. 4 shows the specific volume versus the dry content, comparing the results V 10 obtained for an exemplary embodiment of the shoe press 10 of the invention with a relatively long press shoe 12 again with the results V s for a conventional press provided with a suction press roll.
  • FIG. 5 shows in a schematic partial representation of another embodiment of a shoe press 10 according to the invention.
  • the angle ⁇ between the tangent 30 applied to the drying or tissue cylinder 16 at the end of the press nip 12 and the carrier web 18 leaving the press nip 12 has a significant influence on the dry content of the tissue web 28.
  • the present embodiment is characterized in that, in particular for producing a tissue web 28, this angle .alpha.
  • Between the tangent 30 applied to the drying or tissue cylinder 16 at the end of the press nip 12 and the carrier web 18 expiring from the press nip 12 is .gtoreq.10.degree .. in particular ⁇ 18 ° and preferably ⁇ 20 °. This results in a dry content increase of about 1 to 3% compared to applications with suction press rolls.
  • the press belt 18 is preferably grooved and / or blind drilled.
  • the present shoe press 10 again has the same structure as that according to FIG. 1 , Corresponding elements are provided with the same reference numerals.

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  • Paper (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

Abstract

Between a shoe-pressing unit (14) and a dry/tissue cylinder (16) there is a pressed gap (12), the length (L) of which, when considered in the direction (I) a ribbon runs, is greater than a value of about 80 mm and, preferably, smaller than 200 mm, and 150 mm at most. A pressure profiled section in the pressed gap that results from the length of the pressed gap has a maximum pressing pressure less than or equal to, a value of about 2 MPa. An independent claim is also included for a method producing strips of fibrous material, especially strips of tissue and sanitary paper.

Description

Die Erfindung betrifft eine Maschine zur Herstellung einer Faserstoffbahn, insbesondere Tissue- oder Hygienepapierbahn, mit wenigstens einem zwischen einer Schuhpresseinheit und einem Trocken- bzw. Tissuezylinder gebildeten Pressspalt, durch den ein wasseraufnehmendes Trägerband, ein wasserundurchlässiges Pressband und die Faserstoffbahn hindurchgeführt sind. Sie betrifft ferner ein Verfahren zur Herstellung einer Faserstoffbahn.The invention relates to a machine for producing a fibrous web, in particular tissue or tissue paper web, with at least one press nip formed between a shoe press unit and a dryer or tissue cylinder, through which a water-absorbing carrier tape, a water-impermeable press belt and the fibrous web are passed. It further relates to a method for producing a fibrous web.

In der DE-A-42 24 730 sind mehrere Ausführungsformen einer Maschine der eingangs genannten Art beschrieben. Dabei sind bei sämtlichen Ausführungsformen jeweils wenigstens zwei Pressspalte vorgesehen. Die in Bahnlaufrichtung betrachtet hinten liegende Hauptpresse umfasst jeweils einen Trockenzylinder sowie ein zugeordnetes Anpresselement. Als solches Anpresselement kann eine Saugpresswalze oder eine Schuhpresswalze vorgesehen sein.In the DE-A-42 24 730 Several embodiments of a machine of the type mentioned are described. In each case at least two press gaps are provided in all embodiments. The main press, as viewed in the direction of web travel, comprises a drying cylinder and an associated pressing element. As such a pressing element may be provided a suction press roll or a shoe press roll.

Auch bei einer aus der DE-A-196 54 197 bekannten Maschine der eingangs genannten Art sind wieder zwei Pressspalte vorgesehen. Die hinten liegende Hauptpresse ist durch eine Schuhpresseinheit und einen Trockenzylinder gebildet.Even with one from the DE-A-196 54 197 known machine of the type mentioned again two press nips are provided. The rear main press is formed by a shoe press unit and a drying cylinder.

Weiterhin ist aus dem Dokument EP 0 289 477 A2 ein Verfahren zum Heißpressen und Trocknen einer Faserstoffbahn bekannt, welches einen ersten Schritt, in welchem die Faserbahn einer relativ langen Presszeit bei relativ geringem Pressdruck ausgesetzt ist (erster Nip), einen zweiten Schritt, in welchem der Pressdruck signifikant abgesenkt wird, und einen dritten Schritt, in welchem ein schneller Druckanstieg durchgeführt wird, umfasst. Auch hier sind somit zwei Pressnipdurchgänge mit unterschiedlichen Längen und Presskräften vorgesehen.Furthermore, from the document EP 0 289 477 A2 a method of hot pressing and drying a fibrous web is known, which comprises a first step in which the fibrous web is subjected to a relatively long pressing time at a relatively low pressing pressure (first nip), a second step in which the pressing pressure is lowered significantly, and a third step in which a rapid increase in pressure is carried out. Here too two press nip passages with different lengths and pressing forces are thus provided.

Bei den bekannten Maschinen sind somit stets zwei oder mehrere Pressspalte vorgesehen. Dies wird hier für zwingend erforderlich erachtet, um einerseits eine insbesondere bei der Herstellung einer Tissue- oder Hygienepapierbahn geforderte schonende Entwässerung ohne Verdrücken und andererseits eine verbesserte Produktionsleistung durch einen erhöhten Trockengehalt nach der Presse zu erzielen. Dabei wird mit dem vollständigen oder teilweisen Ersetzen der Walzenspaltpressen durch Schuhpressen infolge der entsprechenden Spaltverlängerung bzw. Erhöhung der Presszeit eine schonende Entwässerung der Bahn ohne Verdrückungen erreicht.In the known machines thus always two or more press nips are provided. This is considered to be absolutely necessary in order to achieve, on the one hand, a gentle dewatering, in particular in the manufacture of a tissue or tissue paper web, without swelling and, on the other hand, an improved production capacity due to an increased dry content after the press. It is achieved with the complete or partial replacement of the nip presses by shoe presses due to the corresponding gap extension or increase the pressing time a gentle drainage of the web without displacements.

Ein wesentlicher Nachteil dieser bekannten Ausführungen besteht nun aber in den gemessen an den erreichten Verbesserungen relativ hohen Investitions- und Betriebskosten. Angesichts der bisher üblichen Begrenzung der maximalen Linienkraft auf einen Wert im Bereich von 90 kN z.B. für Yankee-Zylinder war es bei den bekannten Pressenkonzepten stets erforderlich, wenigstens zwei Pressspalte vorzusehen.However, a major disadvantage of these known embodiments is now in terms of the achieved improvements relatively high investment and operating costs. Given the usual limit of maximum line force to a value in the range of 90 kN, eg for Yankee cylinders, it was always necessary in the known press concepts to provide at least two press nips.

Ziel der Erfindung ist es, eine Maschine sowie ein Verfahren der eingangs genannten Art zu schaffen, mit denen unter Vermeidung der zuvor genannten Nachteile sowie unter weitgehender Einhaltung der für die produzierte Bahn geforderten Qualitätsmerkmale ein möglichst hoher Trockengehalt und/oder spezifisches Volumen erzielbar ist.The aim of the invention is to provide a machine and a method of the type mentioned, with which the highest possible dry content and / or specific volume can be achieved while avoiding the disadvantages mentioned above and while largely adhering to the quality characteristics required for the produced web.

Bei einer in der EP-A2-0 852 273 beschriebenen Entwässerungspresse einer der Herstellung einer Papier- und/oder Kartonbahn dienenden Maschine beträgt die Verweilzeit der Bahn in einem verlängerten Pressspalt weniger als 12 ms.At one in the EP-A2-0 852 273 described dewatering press one of the production of a paper and / or board web serving machine, the residence time of the web in an extended press nip is less than 12 ms.

Diese Aufgabe wird hinsichtlich der Maschine erfindungsgemäß dadurch gelöst, dass wenigstens ein zwischen einer Schuhpresseinheit und dem Trocken- bzw. Tissuezylinder gebildeter Pressspalt vorgesehen ist, dessen in Bahnlaufrichtung betrachtete Länge größer als ein Wert von etwa 80 mm und vorzugsweise kleiner als 200 mm, insbesondere höchstens 150 mm, ist, so dass die zu entwässernde Faserstoffbahn in dem Pressspalt (12) für eine Zeitdauer von wenigstens 3,5 ms einem Pressdruck ausgesetzt wird und dessen sich über die Pressspaltlänge ergebendes Druckprofil einen maximalen Pressdruck aufweist, der kleiner oder gleich einem Wert von etwa 2 MPa ist, wobei das Trägerband und die Faserstoffbahn in Bahnlaufrichtung vor dem Trockenzylinder über wenigstens eine Saugvorrichtung geführt sind.With regard to the machine, this object is achieved according to the invention by providing at least one press nip formed between a shoe press unit and the dryer or tissue cylinder whose length considered in the web running direction is greater than a value of about 80 mm and preferably less than 200 mm, in particular at most 150 mm, so that the fibrous web to be dewatered is subjected to a pressing pressure in the press nip (12) for a period of at least 3.5 ms and its pressure profile resulting from the press nip length has a maximum compacting pressure which is less than or equal to a value of is about 2 MPa, wherein the carrier tape and the fibrous web are guided in the web running direction in front of the drying cylinder via at least one suction device.

Mit einer solchen Ausbildung wird völlig unerwartet eine wesentliche Steigerung sowohl des Trockengehalts als auch des spezifischen Volumens der Faserstoffbahn erreicht. Dies ist um so überraschender, als mit der vorgeschlagenen Lösung der bisher in der Pressenentwicklung eingeschlagene Weg verlassen wird, dessen Zielsetzung darin bestand, mit dem Ersetzen der Walzenspaltpressen durch Schuhpressen mit verlängertem Pressspalt ein schonendes, langsames Entwässern als Voraussetzung für optimale Ergebnisse zu bewirken. Aufgrund der erfindungsgemäßen Ausbildung können nunmehr beispielsweise viele Tissue-Papiermaschinen mit lediglich einem einzigen Schuhpressspalt verwirklicht werden.With such a design, a substantial increase in both the dry content and the specific volume of the fibrous web is achieved completely unexpectedly. This is all the more surprising, as is left with the proposed solution of the previously embarked in the press development path whose objective was to effect the replacement of the nip presses by shoe presses with extended nip gentle, slow dewatering as a prerequisite for optimal results. Due to the invention Training now, for example, many tissue paper machines can be realized with only a single shoe press nip.

Dabei wird insbesondere auch dem Umstand Rechnung getragen, dass bei längeren Schuhen wider Erwarten der erreichbare Trockengehalt geringer wird.In particular, the circumstance is taken into account that for longer shoes, contrary to expectations, the achievable dry content is lower.

Hierbei wird das spezifische Volumen ebenfalls leicht erhöht. Eine solche Erhöhung kann beispielsweise etwa 5 % betragen. Zu einer erheblichen Steigerung kommt es bezüglich des Trockengehalts, was insbesondere im Vergleich zu einem Pressspalt gilt, der mittels einer Saugpresswalze oder durch eine Schuhpresse mit einer Spaltlänge von beispielsweise 120 mm gebildet wird. In diesem Fall ist beispielsweise eine Steigerung des Trockengehalts um etwa 2,5 bis 3 % möglich, wenn von einer konstanten Linienkraft von etwa 90 kN/m ausgegangen wird. Ein solcher Wert darf bei den bisher üblichen Yankee-Zylindern angesichts einer maximal zulässigen mechanischen Beanspruchung nicht überschritten werden. Die Erfindung ist daher insbesondere auch bei Umbauten bestehender Pressen mit besonderem Vorteil einsetzbar. So können gegenüber den herkömmlichen Pressen trotz einer jeweiligen Linienkraftbegrenzung Trockengehaltssteigerungen sowie konstante oder auch höhere Werte des spezifischen Volumens (Bulk) erzielt werden.Here, the specific volume is also slightly increased. Such an increase may be for example about 5%. There is a significant increase in terms of dry content, which is particularly true in comparison to a press nip, which is formed by means of a suction press roll or by a shoe press with a gap length of, for example, 120 mm. In this case, for example, an increase in dry content of about 2.5 to 3% is possible, assuming a constant line force of about 90 kN / m. Such a value must not be exceeded in the usual Yankee cylinders in view of a maximum allowable mechanical stress. The invention can therefore be used with particular advantage especially in conversions of existing presses. Thus, in spite of a respective linear force limitation, dry content increases as well as constant or higher values of the specific volume (bulk) can be achieved in comparison to conventional presses.

Es ist von Vorteil, wenn die Verweilzeit der Faserstoffbahn im Pressspalt insbesondere größer oder gleich 4 ms ist. Dabei kann die Verweilzeit insbesondere definiert sein durch das Verhältnis von Spalt- bzw. Schuhlänge zur Bahngeschwindigkeit.It is advantageous if the residence time of the fibrous web in the press nip is in particular greater than or equal to 4 ms. In this case, the residence time can be defined in particular by the ratio of gap or shoe length to the web speed.

Die durch den Pressspalt erzeugte maximale Linienkraft kann beispielsweise in einem Bereich von etwa 90 bis etwa 120 kN/m liegen.For example, the maximum line force generated by the press nip may be in the range of about 90 to about 120 kN / m.

Bei einer zweckmässigen praktischen Ausführungsform der erfindungsgemässen Maschine umfasst die Schuhpresseinheit einen Pressschuh, der über mehrere quer zur Bahnlaufrichtung nebeneinander angeordnete Anpresselemente gegen den Trockenzylinder pressbar ist. Damit kann ein jeweils gewünschtes Presskraftquerprofil zur Vergleichmässigung der Bahneigenschaften insbesondere an den Bahnrändern eingestellt werden.In an expedient practical embodiment of the inventive machine, the shoe press unit comprises a press shoe, which can be pressed against the drying cylinder via a plurality of contact elements arranged side by side transversely to the web running direction. Thus, a respective desired pressing force transverse profile can be adjusted to even out the web properties, in particular at the web edges.

Als Trockenzylinder kann insbesondere ein Kreppzylinder, d.h. ein sogenannter Yankee-Zylinder vorgesehen sein.As a drying cylinder, a creping cylinder, i. a so-called Yankee cylinder may be provided.

Das sich über die Pressspaltlänge ergebende Druckprofil ist vorzugsweise asymmetrisch.The pressure profile resulting over the press nip length is preferably asymmetrical.

Vorzugsweise liegt der maximale Pressdruck in dem in Bahnlaufrichtung betrachtet hinteren Viertel der Pressspaltlänge.The maximum pressing pressure is preferably in the rear quarter of the press nip length viewed in the web running direction.

Es kann von Vorteil sein, wenn der mittlere Druckanstiegsgradient in dem vom Spaltanfang bis zum maximalen Pressdruck reichenden Abschnitt des Druckprofils bei einem neuwertigen Trägerband größer oder gleich einem Wert von etwa 40 kPa/mm, insbesondere größer oder gleich etwa 60 kPa/mm und vorzugsweise größer oder gleich etwa 120 kPa/mm ist.It may be advantageous if the average pressure rise gradient in the section of the pressure profile reaching from the gap beginning to the maximum pressing pressure at a new carrier strip is greater than or equal to a value of about 40 kPa / mm, in particular greater than or equal to about 60 kPa / mm and preferably greater or equal to about 120 kPa / mm.

Der mittlere Druckabfallsgradient im Endbereich des Druckprofils ist bei einem neuwertigen Trägerband vorzugsweise größer oder gleich einem Wert von etwa 300 kPa/mm, insbesondere größer oder gleich etwa 500 kPa/mm und vorzugsweise größer oder gleich etwa 800 kPa/mm. Der mittlere Druckabfallsgradient im Endbereich nimmt mit zunehmender Betriebszeit des Filzes zu. Dadurch werden bei einem erfindungsgemäßen Pressspalt Werte von über 1000 bis über 1600 kPa/m erreicht.The mean pressure drop gradient in the end region of the pressure profile is preferably greater than or equal to a value of about 300 kPa / mm, in particular greater than or equal to about 500 kPa / mm, and preferably greater than or equal to about 800 kPa / mm in a new carrier tape. The mean pressure drop gradient in the end region increases with increasing operating time of the felt. As a result, values of more than 1000 to more than 1600 kPa / m are achieved in a press nip according to the invention.

Bei einer bevorzugten praktischen Ausführungsform liegt das wasseraufnehmende Trägerband im Pressspalt zwischen dem wasserundurchlässigen Pressband und der Faserstoffbahn, wobei die Faserstoffbahn den Trockenzylinder berührt.In a preferred practical embodiment, the water-absorbing carrier tape lies in the press nip between the water-impermeable press belt and the fibrous web, the fibrous web contacting the drying cylinder.

Als wasseraufnehmendes Trägerband kann insbesondere ein Filz vorgesehen sein. Ein solcher Filz kann beispielsweise ein Flächengewicht besitzen, das kleiner oder gleich einem Wert von etwa 1450 g/m2 ist. Es ist beispielsweise ein in besonderer Weise strukturierter Filz in der Art eines mit Höckern versehenen Prägesiebes oder -filzes, d.h. eines sogenannten "imprinting fabric" oder "imprinting felt" (siehe beispielsweise WO98/00604 ) oder eines eine grob strukturierte Oberfläche aufweisenden "patterning fabric" oder "patterning felt" verwendbar. Die speziellen Trägerbänder wirken sich insbesondere in Kombination mit einem erfindungsgemäßen Pressspalt mit einer Pressspaltlänge größer oder gleich etwa 80 mm vorteilhaft auf das spezifische Volumen der produzierten Papierbahn aus.As a water-absorbing carrier tape may be provided in particular a felt. Such a felt may, for example, have a basis weight which is less than or equal to a value of about 1450 g / m 2 . It is, for example, a specially structured felt in the manner of a bumped embossing screen or felt, ie a so-called "imprinting fabric" or "imprinting felt" (see, for example, US Pat WO98 / 00604 ) or a roughly textured surface having "patterning fabric" or "patterning felt" usable. The special carrier tapes, in particular in combination with a press nip according to the invention having a press nip length greater than or equal to about 80 mm, have an advantageous effect on the specific volume of the paper web produced.

Das wasseraufnehmende Trägerband kann in Dickenrichtung eine unterschiedfiche Beschaffenheit aufweisen. So kann die der Faserstoffbahn zugewandte Seite des Trägerbandes beispielsweise eine feinere Struktur besitzen als dessen von der Faserstoffbahn abgewandte Seite.The water-absorbing carrier tape may have a different texture in the thickness direction. Thus, the fibrous web facing side of the carrier tape, for example, have a finer structure than its side facing away from the fibrous web page.

Bei einer zweckmässigen praktischen Ausführungsform besitzt das Pressband eine gerillte und/oder mit Blindbohrungen versehene Oberfläche, wie dies beispielsweise in der DE-A-196 54 198 beschrieben ist.In an expedient practical embodiment, the press belt has a grooved and / or provided with blind holes surface, as for example in the DE-A-196 54 198 is described.

Grundsätzlich kann am Trockenzylinder auch ein weiterer Pressspalt gebildet sein. Dabei kann es in bestimmten Anwendungsfällen zweckmässig sein, wenn am Trockenzylinder wenigstens zwei mittels einer jeweiligen Schuhpresseinheit gebildete Pressspalte vorgesehen sind. Grundsätzlich ist es auch denkbar, in Bahnlaufrichtung vor dem Trockenzylinder einen zusätzlichen Pressspalt vorzusehen.In principle, a further press nip can also be formed on the drying cylinder. It may be useful in certain applications, if at least two press gaps formed by a respective shoe press unit are provided on the drying cylinder. In principle, it is also conceivable to provide an additional press nip in the web running direction in front of the drying cylinder.

Zweckmäßigerweise kann die wenigstens eine Saugvorrichtung bzw. Saugkasten vorgesehen sein, die eine Saugwalze und/oder einen Saugschuh umfasst.Conveniently, the at least one suction device or suction box may be provided which comprises a suction roll and / or a suction shoe.

Bei einer bevorzugten praktischen Ausführungsform der erfindungsgemässen Maschine ist als Schuhpresseinheit eine Schuhpresswalze vorgesehen.In a preferred practical embodiment of the machine according to the invention, a shoe press roll is provided as the shoe press unit.

Von Vorteil ist zudem, wenn die Schuhpresseinheit wenigstens einen austauschbaren Pressschuh umfasst.It is also advantageous if the shoe press unit comprises at least one exchangeable press shoe.

Das erfindungsgemäße Verfahren ist dadurch gekennzeichnet, dass die zu entwässernde Faserstoffbahn in dem Pressspalt, dessen in Bahniaufrichtung betrachtete Länge (L) größer als ein Wert von etwa 80 mm ist, für eine Zeitdauer von wenigstens 3,5 ms einem Pressdruck von höchstens 2 MPa ausgesetzt ist.The method according to the invention is characterized in that the fibrous web to be dewatered is subjected to a pressing pressure of at most 2 MPa for a period of at least 3.5 ms in the press nip whose length (L) considered in the web erection is greater than a value of about 80 mm is.

Die Erfindung ist beispielsweise anwendbar für einen Crescent-Former, eine Langsieb-Tissue-Papiermaschine, einen Doppelsiebformer, eine Saugbrustwalzenmaschine usw.The invention is applicable to, for example, a crescent former, a four-wire tissue paper machine, a twin-wire former, a suction breast roll machine, etc.

Der Stoffeintrag zur Herstellung beispielsweise einer Tissuebahn kann beispielsweise aus gemahlenem Stoff ("refined pulp") bestehen. Hier kann der erfindungsgemässe Pressspalt besonders vorteilhaft zur Trockengehaltssteigerung eingesetzt werden.The substance input for the production of, for example, a tissue web can consist, for example, of "refined pulp". Here, the inventive press nip can be used particularly advantageous for dry content increase.

Ein solcher beispielsweise zur Herstellung einer Tissuebahn dienender Stoffeintrag kann aber auch aus ungemahlenem Stoff bestehen. In diesem Fall kann der erfindungsgemässe lange Pressspalt besonders vorteilhaft zur Steigerung des spezifischen Volumens eingesetzt werden.However, such a fabric feed serving, for example, for producing a tissue web may also consist of unground material. In this case, the inventive long press nip can be used particularly advantageously for increasing the specific volume.

Die Erfindung ist beispielsweise auch für sogenannte "curled fibres" anwendbar. Die Stoffsuspension enthält in diesem Fall einen Anteil von Fasern, die einer besonderen Behandlung unterworfen wurden. Dabei werden die im Wesentlichen geradlinig bzw. in einer Ebene gekrümmten Zellstofffasern so gekrümmt, dass eine räumliche Faserform beispielsweise nach Art einer Spirale entsteht.The invention is also applicable for example for so-called "curled fibers". The stock suspension in this case contains a proportion of fibers which have been subjected to a special treatment. Here, the substantially linear or curved in a plane pulp fibers are curved so that a spatial fiber shape, for example, arises in the manner of a spiral.

Die Erfindung ist insbesondere auch in einer Tissue-Papiermaschine mit wenigstens einem sogenannten "Through-air-drying"-Trocknungsprozess anwendbar, wobei der erfindungsgemässe Pressspalt insbesondere vor einer entsprechenden "Through-air-drying"-Einrichtung eingesetzt wird. Eine solche Kombination ist insbesondere hinsichtlich eines hohen Trockengehalts und eines hohen spezifischen Volumens von Vorteil. Durch den erfindungsgemäßen Pressspalt wird somit einerseits ein hoher Trockengehalt erreicht, wodurch die Betriebskosten der energieintensiven Trocknungsphase reduziert werden. Andererseits wird die Bahn allenfalls geringfügig verdichtet, was bedeutet, dass das spezifische Volumen der Bahn erhöht wird bzw. bei höheren Pressdrücken unbeeinträchtigt bleibt, wodurch insbesondere auch das "Through-air-drying"-Trocknungsverfahren effizienter und wirtschaftlicher wird.The invention can also be used in particular in a tissue paper machine with at least one so-called "through-air-drying" drying process, wherein the press nip according to the invention is used in particular before a corresponding "through-air-drying" device. Such a combination is particularly advantageous in terms of a high dry content and a high specific volume. Thus, on the one hand, a high dry content is achieved by the press nip according to the invention, whereby the operating costs of the energy-intensive drying phase are reduced. On the other hand, the web is at most slightly compacted, which means that the specific volume of the web is increased or remains unimpaired at higher pressing pressures, which also makes the "through-air-drying" drying process more efficient and economical.

Die Erfindung ist insbesondere auch bei der Herstellung von mehrschichtigen Bahnen unter Verwendung eines einzigen Stoffauflaufs oder der Herstellung mehrlagiger Bahnen unter Verwendung mehrerer Stoffaufläufe anwendbar.In particular, the invention is also applicable to the manufacture of multilayer webs using a single headbox or the manufacture of multilayer webs using multiple headboxes.

Die Erfindung wird im Folgenden anhand von Ausführungsbeispielen unter Bezugnahme auf die Zeichnung näher beschrieben; in dieser zeigen:

Figur 1
eine rein schematische Teildarstellung einer erfindungsgemäßen Schuhpresse mit einem zwischen einer Schuhpresseinheit und einem Trockenzylinder gebildeten Pressspalt,
Figur 2
den Pressdruckverlauf einer herkömmlichen Schuhpresse,
Figur 3
einen Vergleich des Pressdruckverlaufs einer beispielhaften Ausführungsform der erfindungsgemäßen Schuhpresse mit relativ langem Pressschuh mit dem Pressdruckverlauf einer mit einer Saugpresswalze versehenen herkömmlichen Presse,
Figur 4
das spezifische Volumen gegenüber dem Trockengehalt, wobei die für eine beispielhafte Ausführungsform der erfindungsgemässen Schuhpresse mit relativ langem Pressschuh erhaltenen Ergebnisse mit denen für eine mit einer Saugpresswalze versehenen herkömmlichen Presse verglichen werden, und
Figur 5
eine rein schematische Teildarstellung einer weiteren Ausführungsform der erfindungsgemässen Schuhpresse mit einem zwischen einer Schuhpresseinheit und einem Tissuezylinder gebildeten Pressspalt.
The invention will be described in more detail below by means of embodiments with reference to the drawing; in this show:
FIG. 1
a purely schematic partial view of a shoe press according to the invention with a press nip formed between a shoe press unit and a drying cylinder,
FIG. 2
the pressure pressure curve of a conventional shoe press,
FIG. 3
a comparison of the pressure pressure curve of an exemplary embodiment of the shoe press according to the invention with a relatively long press shoe with the pressure profile of a pressure provided with a suction press conventional press,
FIG. 4
the specific volume compared to the dry content, wherein the results obtained for an exemplary embodiment of the shoe press with a relatively long press shoe according to the invention are compared with those for a conventional press provided with a suction press roll, and
FIG. 5
a purely schematic partial view of another embodiment of the inventive shoe press with a formed between a shoe press unit and a tissue cylinder press nip.

Figur 1 zeigt in rein schematischer Teildarstellung ein Ausführungsbeispiel einer erfindungsgemässen Schuhpresse 10, die beispielsweise in einer Maschine zur Herstellung einer Faserstoffbahn wie insbesondere einer Tissue- oder Hygienepapierbahn einsetzbar ist. FIG. 1 shows a purely schematic partial representation of an embodiment of an inventive shoe press 10, which can be used for example in a machine for producing a fibrous web such as in particular a tissue or tissue paper web.

Der Pressspalt 12 dieser Schuhpresse 10 ist zwischen einer Schuhpresseinheit, im vorliegenden Fall einer Schuhpresswalze 14, und einem Trockenzylinder 16 gebildet, durch den außer der Faserstoffbahn ein wasseraufnehmendes Trägerband 18 sowie ein wasserundurchlässiges Pressband hindurchgeführt ist, bei dem es sich im vorliegenden Fall um den Pressmantel 20 der Schuhpresswalze 14 handelt. Das wasseraufnehmende Trägerband 18 kann insbesondere durch einen Filz gebildet sein. Im vorliegenden Fall ist das wasseraufnehmende Trägerband 18 zwischen dem Pressmantel 20 und der Faserstoffbahn durch den Pressspalt 12 geführt, wobei die Faserstoffbahn den Trockenzylinder 16 berührt.The press nip 12 of this shoe press 10 is formed between a shoe press unit, in the present case a shoe press roll 14, and a drying cylinder 16, through which except the fibrous web, a water-absorbing carrier tape 18 and a water-impervious press belt is passed, which is in the present case to the press cover 20 of the shoe press roll 14. The water-absorbing carrier tape 18 may be formed in particular by a felt. In the present case, the water-absorbing carrier tape 18 is guided between the press cover 20 and the fibrous web through the press nip 12, wherein the fibrous web contacts the drying cylinder 16.

Wie anhand der Figur 1 zu erkennen ist, besitzt die Schuhpresswalze 14 einen zweiteiligen Presssschuh 22, zwischen dessen beiden Teile eine thermische Isolierschicht 24 eingesetzt ist.As based on the FIG. 1 can be seen, the shoe press roll 14 has a two-part press shoe 22, between the two parts of a thermal insulation layer 24 is inserted.

Der Pressschuh 22 kann über mehrere quer zur Bahnlaufrichtung 1 nebeneinander angeordnete Anpresselemente 26 gegen den Trockenzylinder 16 pressbar sein.The press shoe 22 can be pressed against the drying cylinder 16 via a plurality of pressing elements 26 arranged juxtaposed transversely to the web running direction 1.

Bei dem Trockenzylinder 16 kann es sich beispielsweise um einen Yankee-Zylinder handeln.The drying cylinder 16 may be, for example, a Yankee cylinder.

Das beispielsweise durch einen Filz gebildete wasseraufnehmende Trägerband 18 kann in Dickenrichtung eine unterschiedliche Beschaffenheit aufweisen. Dabei kann beispielsweise die der Faserstoffbahn zugewandte Seite des Trägerbandes 18 eine feinere Struktur besitzen als dessen von der Faserstoffbahn abgewandte Seite. Der Pressmantel 20 kann eine glatte, gerillte und/oder mit Blindbohrungen versehene Oberfläche besitzen. Am Trockenzylinder 16 kann wenigstens ein weiterer, hier nicht dargestellter Pressspalt gebildet sein. In Bahnlaufrichtung 1 vor dem Trockenzylinder 16 kann ein zusätzlicher Pressspalt vorgesehen sein. Grundsätzlich können das Trägerband 18 und die Faserstoffbahn in Bahnlaufrichtung 1 vor dem Trockenzylinder 16 auch über wenigstens eine Saugvorrichtung geführt sein. Die Schuhpresseinheit 14 kann wenigstens einen austauschbaren Pressschuh 22 umfassen.The water-absorbing carrier tape 18 formed for example by a felt may have a different texture in the thickness direction. In this case, for example, the fibrous web facing side of the carrier tape 18 have a finer structure than its side facing away from the fibrous web page. The press cover 20 may have a smooth, grooved and / or blind-bore surface. At least one further, not shown here press nip may be formed on the drying cylinder 16. In the web running direction 1 in front of the drying cylinder 16, an additional press nip can be provided. In principle, the carrier tape 18 and the fibrous web in the web running direction 1 in front of the drying cylinder 16 can also be guided via at least one suction device. The shoe press unit 14 may include at least one replaceable press shoe 22.

In der Figur 2 ist das Druckprofil bzw. der Pressdruckverlauf p(L) einer herkömmlichen Schuhpresse dargestellt. Dabei ist der Pressdruck p über der Länge L des Pressspaltes 12 bzw. des Pressschuhes 22 aufgetragen.In the FIG. 2 the pressure profile or the pressure profile p (L) of a conventional shoe press is shown. Here, the pressing pressure p over the length L of the press nip 12 and the press shoe 22 is applied.

Bei einem solchen herkömmlichen Langspalt ergibt sich zunächst ein sehr sanfter Druckanstieg bis zu einem relativ niedrigen maximalen Pressdruck pmax. Im Anschluss an den maximalen Pressdruck pmax dieses Druckverlaufs p(L) erfolgt dann ein schneller Druckabfall.In such a conventional extended nip initially results in a very gentle increase in pressure up to a relatively low maximum pressing pressure p max . Following the maximum pressing pressure p max of this pressure curve p (L) then takes place a rapid pressure drop.

Die erfindungsgemäße Schuhpresse 10 kann nun insbesondere so ausgelegt sein, dass die in Bahnlaufrichtung I betrachtete Länge L des Pressspaltes 12 (vgl. Figur 1) kleiner oder gleich einem Wert von etwa 60 mm ist und dessen sich über die Pressspaltlänge L ergebendes Druckprofil p(L) einen maximalen Pressdruck pmax aufweist, der größer oder gleich einem Wert von etwa 3,3 MPa ist.The shoe press 10 according to the invention can now be designed in particular such that the length L of the press nip 12 considered in the web running direction I (cf. FIG. 1 ) is less than or equal to a value of about 60 mm and whose over the press nip length L resulting pressure profile p (L) has a maximum pressing pressure p max , which is greater than or equal to a value of about 3.3 MPa.

Die Figur 3 zeigt einen Vergleich des Pressdruckverlaufs p10 (L) einer beispielhaften Ausführungsform einer solchen erfindungsgemässen Schuhpresse 10 mit relativ langem Pressschuh 12 mit dem Pressdruckverlauf ps (L) einer mit einer Saugpresswalze versehenen herkömmlichen Presse.The FIG. 3 shows a comparison of the pressing pressure curve p 10 (L) of an exemplary embodiment of such a shoe press 10 according to the invention with a relatively long press shoe 12 with the pressing pressure curve p s (L) provided with a suction press conventional press.

Während der Pressdruckverlauf p10 (L) der erfindungsgemäßen Schuhpresse sowohl für eine maximale Linienkraft von 90 kN/m als auch für eine höhere maximale Linienkraft von 270 kN/m dargestellt ist, ist der Pressdruckverlauf ps (L) der herkömmlichen Presse lediglich für eine maximale Linienkraft von 90 kN/m dargestellt.While the pressure profile p 10 (L) of the shoe press according to the invention for both a maximum line force of 90 kN / m and for a higher maximum line force of 270 kN / m is shown, the compression pressure curve p s (L) of the conventional press only for one maximum line force of 90 kN / m shown.

Gemäß dieser Figur 3 ergibt sich bei der erfindungsgemäßen Schuhpresse 10 ein deutlich längerer Pressspalt 12. Zudem besitzt der entsprechende Pressdruckverlauf p10 (L) einen deutlich niedrigeren maximalen Pressdruck pmax (vgl. den für eine maximale Linienkraft von 90 kN/m angegebenen schraffierten unteren Pressdruckverlauf p10 (L)). Der Figur 3 kann zudem entnommen werden, dass der maximale Pressdruck pmax selbst bei einer wesentlich höheren maximalen Linienkraft von hier 270 kN/m nicht höher als der maximale Pressdruck pmax der herkömmlichen Presse ist, für den im vorliegenden Fall eine maximale Linienkraft von 90 kN/m angegeben ist.According to this FIG. 3 In addition, the corresponding pressing pressure curve p 10 (L) has a significantly lower maximum pressing pressure p max (compare the shaded lower pressing pressure curve p 10 (for the maximum line force of 90 kN / m). L)). Of the FIG. 3 In addition, it can be seen that the maximum pressing pressure p max, even at a substantially higher maximum line force of 270 kN / m, is not higher than the maximum pressing pressure p max of the conventional press, for which in the present case a maximum line force of 90 kN / m is specified.

Figur 4 zeigt das spezifische Volumen gegenüber dem Trockengehalt, wobei die für eine beispielhafte Ausführungsform der erfindungsgemäßen Schuhpresse 10 mit relativ langem Pressschuh 12 erhaltenen Ergebnisse V10 wieder mit den Ergebnissen Vs für eine mit einer Saugpresswalze versehenen herkömmlichen Presse verglichen werden. FIG. 4 shows the specific volume versus the dry content, comparing the results V 10 obtained for an exemplary embodiment of the shoe press 10 of the invention with a relatively long press shoe 12 again with the results V s for a conventional press provided with a suction press roll.

Geht man von einem konstanten maximalen Liniendruck von 90 kN/m aus, so kann bei gleichem Trockengehalt eine Steigerung des spezifischen Volumens von 20 % erreicht werden, wodurch sich eine entsprechend höhere Qualität ergibt. Dagegen kann bei einem gleichen spezifischen Volumen eine Steigerung des Trockengehalts um 4 % erzielt werden, wodurch Energie eingespart oder eine höhere Produktionsrate erzielt wird. Wie anhand der Figur 4 zu erkennen ist, wird hier von einer konstanten maximalen Linienkraft von 270 kN/m ausgegangen.Assuming a constant maximum line pressure of 90 kN / m, an increase in the specific volume of 20% can be achieved with the same dry content, resulting in a correspondingly higher quality. By contrast, with the same specific volume, an increase of 4% in dry matter content can be achieved, saving energy or achieving a higher production rate. As based on the FIG. 4 can be seen here, it is assumed that a constant maximum line force of 270 kN / m.

Figur 5 zeigt in einer schematischen Teildarstellung eine weitere Ausführungsform einer erfindungsgemäßen Schuhpresse 10. FIG. 5 shows in a schematic partial representation of another embodiment of a shoe press 10 according to the invention.

Bei kurzen Schuhen 22 hat sich gezeigt, dass der Winkel α zwischen der am Ende des Pressspaltes 12 an den Trocken- bzw. Tissuezylinder 16 angelegten Tangente 30 und dem aus dem Pressspalt 12 auslaufenden Trägerband 18 einen wesentlichen Einfluss auf den Trockengehalt der Tissuebahn 28 hat. Die vorliegende Ausführungsform zeichnet sich nun dadurch aus, dass insbesondere zur Herstellung einer Tissuebahn 28 dieser Winkel α zwischen der am Ende des Pressspaltes 12 an den Trocken- bzw. Tissuezylinder 16 angelegten Tangente 30 und dem aus dem Pressspalt 12 auslaufenden Trägerband 18 ≥ 10°, insbesondere ≥ 18° und vorzugsweise ≥ 20° ist. Damit ergibt sich gegenüber Anwendungen mit Saugpresswalzen eine Trockengehaltssteigerung von ca. 1 bis 3 %. Das Pressband 18 ist vorzugsweise gerillt und/oder blindgebohrt.For short shoes 22, it has been found that the angle α between the tangent 30 applied to the drying or tissue cylinder 16 at the end of the press nip 12 and the carrier web 18 leaving the press nip 12 has a significant influence on the dry content of the tissue web 28. The present embodiment is characterized in that, in particular for producing a tissue web 28, this angle .alpha. Between the tangent 30 applied to the drying or tissue cylinder 16 at the end of the press nip 12 and the carrier web 18 expiring from the press nip 12 is .gtoreq.10.degree .. in particular ≥ 18 ° and preferably ≥ 20 °. This results in a dry content increase of about 1 to 3% compared to applications with suction press rolls. The press belt 18 is preferably grooved and / or blind drilled.

Im Übrigen besitzt die vorliegende Schuhpresse 10 beispielsweise wieder den gleichen Aufbau wie die gemäß Figur 1. Einander entsprechende Elemente sind mit gleichen Bezugszeichen versehen.Incidentally, for example, the present shoe press 10 again has the same structure as that according to FIG FIG. 1 , Corresponding elements are provided with the same reference numerals.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

1010
Schuhpresseshoe press
1212
Pressspaltpress nip
1414
SchuhpresswalzeShoe press roll
1616
Trockenzylinderdrying cylinders
1818
Trägerbandcarrier tape
2020
Pressband, PressmantelPress belt, press cover
2222
Pressschuhpress shoe
2424
thermische Isolierschichtthermal insulation layer
2626
Anpresselementpresser
2828
Tissuebahntissue web
3030
Tangentetangent
LL
PressspaltlängePress nip length
11
BahnlaufrichtungWeb direction
p(L)p (L)
Pressdruckverlauf, DruckprofilCompression pressure profile, pressure profile
pmax p max
maximaler Pressdruckmaximum pressing pressure
αα
Winkelangle

Claims (11)

  1. Machine for the manufacture of a fibrous web, in particular a tissue or hygienic paper web, having at least one press nip (12) which is formed between a shoe press unit (14) and a drying or tissue cylinder (16) and through which a water-absorbing carrier belt (18), a water-impermeable press belt (20) and the fibrous web are led, characterized in that at least one press nip (12) formed between a shoe press unit (14) and the drying or tissue cylinder (16) is provided, of which the length (L), viewed in the web running direction (I), is greater than a value of approximately 80 mm, so that the fibrous web to be dewatered is subjected to a pressing pressure for a time period of at least 3.5 ms in the press nip (12) and of which the pressure profile (p(L)) resulting over the press nip length (L) has a maximum pressing pressure (pmax) which is less than or equal to a value of approximately 2 MPa, with the carrier belt (18) and the fibrous web being led over at least one suction device before the drying cylinder (16) in the web running direction.
  2. Machine according to Claim 1, characterized in that the maximum line force produced in the press nip (12) lies in a range from approximately 90 to approximately 110 kN/m, and/or in that the shoe press unit (14) comprises a press shoe (22) which can be pressed against the drying cylinder by a plurality of pressing elements (26) which are arranged beside one another transversely with respect to the web running direction (I) and can preferably be actuated independently of one another.
  3. Machine according to Claim 1 or 2, characterized in that the drying cylinder (16) provided is a Yankee cylinder, and/or in that the pressure profile (p(L)) resulting over the press nip length (L) is asymmetrical.
  4. Machine according to one of Claims 1 to 3, characterized in that the pressure profile (p(L)) has a maximum pressing pressure (pmax) which is less than or equal to a value of approximately 2 MPa, and in that the maximum pressing pressure (pmax) is located in the rear quarter of the press nip length (L), as viewed in the web running direction (I).
  5. Machine according to one of the preceding claims, characterized in that the average pressure rise gradient in the section of the pressure profile (p(L)) reaching from the start of the nip as far as the maximum pressing pressure (pmax) in the case of a new carrier belt is greater than or equal to a value of approximately 40 kPa/mm, in particular greater than or equal to approximately 60 kPa/mm and preferably greater than or equal to approximately 120 kPa/mm, and/or in that the average pressure drop gradient in the end region of the pressure profile (p(L)) in the case of a new carrier belt is greater than or equal to a value of approximately 300 kPa/mm, in particular greater than or equal to approximately 500 kPa/mm, expediently greater than or equal to approximately 800 kPa/mm, and is preferably greater than or equal to approximately 960 kPa/mm, and/or in that the water-absorbing carrier belt (18) in the press nip (12) is located between the water-impermeable press belt (20) and the fibrous web and the fibrous web touches the drying cylinder (16), and/or in that the water-absorbing carrier belt (18) provided is a felt.
  6. Machine according to one of the preceding claims, characterized in that the water-absorbing carrier belt (18) has a different composition in the thickness direction, and in that the side of the carrier belt (18) facing the fibrous web preferably has a finer structure than its side facing away from the fibrous web.
  7. Machine according to one of the preceding claims, characterized in that the press belt (20) has a surface that is smooth, grooved and/or provided with blind drilled holes, and/or in that at least one further press nip (12) is formed on the drying cylinder (16), at least two press nips (12) formed by means of a respective shoe press unit (14) preferably being provided on the drying cylinder (16).
  8. Machine according to one of the preceding claims, characterized in that, in the web running direction (I), an additional press nip (12) is provided before the drying cylinder (16), and/or in that the shoe press unit provided is a shoe press roll (14), the press belt preferably being formed by the press shell (20) of the shoe press roll (14).
  9. Machine according to one of the preceding claims, characterized in that the shoe press unit (14) comprises at least one replaceable press shoe (22), and/or in that the carrier belt (18) provided is a structured felt of the type of an embossing fabric or felt provided with elevations, that is to say what is known as an "imprinting fabric" or "imprinting felt" or a "patterning fabric" or "patterning felt" having a coarsely structured surface.
  10. Use of the machine according to one of the preceding claims for the manufacture of a fibrous web by using what are known as "curled fibres".
  11. Method for the manufacture of a fibrous web, in particular a tissue or hygienic paper web, in which the fibrous web to be dewatered, together with a carrier belt (18), is led through a press nip (12) formed between a shoe press unit (14) and a drying or tissue cylinder (16), through which nip a water-absorbent carrier belt (18), a water-impermeable press belt (20) and the fibrous web are led,
    characterized in that the fibrous web to be dewatered is subjected to a pressing pressure of at most 2 MPa for a time period of at least 3.5 ms in the press nip (12), of which the length (L) viewed in the web running direction (I) is greater than a value of approximately 80 mm, with the carrier belt (18) and the fibrous web being led over at least one suction device before the drying cylinder (16) in the web running direction.
EP07106782A 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web Expired - Lifetime EP1816256B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19860687A DE19860687A1 (en) 1998-12-29 1998-12-29 Machine and method for producing a fibrous web
EP99125789A EP1016754B1 (en) 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web

Related Parent Applications (2)

Application Number Title Priority Date Filing Date
EP99125789A Division EP1016754B1 (en) 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web
EP99125789.0 Division 1999-12-23

Publications (2)

Publication Number Publication Date
EP1816256A1 EP1816256A1 (en) 2007-08-08
EP1816256B1 true EP1816256B1 (en) 2011-12-21

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EP07106782A Expired - Lifetime EP1816256B1 (en) 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web
EP99125789A Expired - Lifetime EP1016754B1 (en) 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web

Family Applications After (1)

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EP99125789A Expired - Lifetime EP1016754B1 (en) 1998-12-29 1999-12-23 Machine and method for the manufacture of a fibrous web

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US (4) US6746574B2 (en)
EP (2) EP1816256B1 (en)
AT (2) ATE538243T1 (en)
BR (1) BR9906261B1 (en)
CA (4) CA2718031C (en)
DE (2) DE19860687A1 (en)

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DE10032923A1 (en) * 2000-07-06 2002-01-24 Bosch Gmbh Robert Fuel injection device for internal combustion engines
DE60110362T3 (en) * 2001-02-16 2009-01-15 The Procter & Gamble Company, Cincinnati Method for producing a thick and smooth embossed web
DE10209582A1 (en) * 2002-03-05 2003-09-18 Voith Paper Patent Gmbh Machine for making a tissue web
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DE102014213512A1 (en) 2014-07-11 2016-01-14 Voith Patent Gmbh Machine for producing a fibrous web
CN106988150B (en) * 2017-05-23 2019-06-25 东莞市白天鹅纸业有限公司 A kind of paper for daily use paper machine
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Also Published As

Publication number Publication date
US6746574B2 (en) 2004-06-08
US20040194904A1 (en) 2004-10-07
EP1016754A1 (en) 2000-07-05
US7332059B2 (en) 2008-02-19
US7288168B2 (en) 2007-10-30
CA2718288A1 (en) 2000-06-29
EP1016754B1 (en) 2008-06-25
BR9906261B1 (en) 2009-12-01
CA2718114C (en) 2013-02-12
CA2293215C (en) 2011-08-30
CA2718114A1 (en) 2000-06-29
CA2718031C (en) 2012-10-09
US20020069995A1 (en) 2002-06-13
DE19860687A1 (en) 2000-07-06
US7326320B2 (en) 2008-02-05
CA2293215A1 (en) 2000-06-29
US20040134632A1 (en) 2004-07-15
ATE538243T1 (en) 2012-01-15
DE59914794D1 (en) 2008-08-07
ATE399224T1 (en) 2008-07-15
US20040261967A1 (en) 2004-12-30
BR9906261A (en) 2000-08-22
EP1816256A1 (en) 2007-08-08
CA2718031A1 (en) 2000-06-29

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