EP0391025B1 - Twin-wire former - Google Patents
Twin-wire former Download PDFInfo
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- EP0391025B1 EP0391025B1 EP90101039A EP90101039A EP0391025B1 EP 0391025 B1 EP0391025 B1 EP 0391025B1 EP 90101039 A EP90101039 A EP 90101039A EP 90101039 A EP90101039 A EP 90101039A EP 0391025 B1 EP0391025 B1 EP 0391025B1
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- European Patent Office
- Prior art keywords
- wire
- forming
- twin
- former according
- roll
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
- D21F9/003—Complete machines for making continuous webs of paper of the twin-wire type
Definitions
- the invention relates to a twin wire former according to the preamble of claim 1.
- twin wire former is known from DE-A-20 51 444.
- the forming roller used there is not in the area of the suspension jet arriving from the headbox. The water thrown upwards is collected in a tub and braked.
- DE-OS 31 23 132 shows a further twin wire former, but with pre-dewatering.
- the front forming roller is arranged as an open forming roller above the top wire and throws water diagonally upwards, without however causing a propelling effect for secondary jets which occur in the area of the drainage strips , since here the rays run almost parallel at essentially the same speed.
- twin-wire formers which work with an upper front forming roll and in the area of the upper wire, have drainage bars resting thereon, work with suction boxes which are arranged between the drainage bars in order to discharge the water laterally from the device.
- the invention has for its object a twin wire former of the beginning to create the type mentioned, in which a more gentle and better drainage can be achieved within the forming zone in such a way that the formation process can be improved and in particular evened out without a negative influence on the retention of the fibers.
- this water guiding element can be optimally, preferably relatively flatly curved, in adaptation to the flow conditions, i.e. approximate the course of the sieve.
- the thrown-off water jet has a driving effect in that the optimal alignment and the optimal guidance of the thrown-off water jet as driving jet have a driving effect for the secondary jets in the area of the drainage strips. This applies in particular if there is a loss of energy in the area of the molding strips for water drainage.
- the formation is also improved in that the drainage strips, which act as forming strips, rest on the upper sieve and in particular are pressed against them, so that the twin wire is deflected.
- the forming strips are arranged in the rear half and in particular in the last third of the forming zone, it is avoided that the violent driving jet strikes the forming strips just behind the forming roller.
- An essential advantage for the invention is the fact that the suspension, which has not been pre-dewatered, is fed to the converging twin wire and then dewatered in the loop area of the twin wire around the front forming roller, thus producing a very violent driving jet.
- the angle at which the twin wire wraps around the forming roller is preferably 5 o to 120 o and in particular approximately 20 o . This wrap affects the strength of the jet.
- the driving jet thicknesses can be between 2 and 19 mm, depending on the web speed of 300 to 2000 m / min. The driving jet usually makes up about 40% of the amount that is dewatered in the top sieve alone.
- two or three and in particular three forming strips are provided.
- the forming blades may be oriented inclined towards the Siebverlaufes and take it to the screen an angle of 20 ° to 90 ° and in particular approximately 37 o a. This affects the transition of the secondary jets along the forming strips into the main driving jet.
- the forming strips are preferably arranged at a distance of less than 200 mm in order to achieve the best effect.
- the water guiding element as the inner contour of an upper trough can initially rise flat from the forming roller, then be arranged essentially horizontally and then fall again towards the end of the forming zone, this guiding element being largely flat, so that the water jets are applied as a film flow by centrifugal force.
- vacuum boxes can also be provided.
- the forming roller can also be designed as a suction roller so that the lower drainage pressure of the outer wire that occurs at high speeds can be compensated for by vacuum.
- front and rear refer to the running direction of the sieves and in particular the double sieve.
- a forming roll 10 is shown schematically, namely as a so-called open forming roll, in the peripheral surface of which chambers are formed.
- a lower wire 12 is fed to a suspension feed nip 14 which is formed by the lower wire 12 fed around the forming roller 10 and the upper wire 18 fed by a deflecting roller 16, the two wires meeting at a point D and from there to a twin wire form.
- a suspension feed nozzle 20 is assigned to this feed gap 14.
- the twin wire wraps around the forming roller 10 at an angle alpha which is between 5 o and 120 o , in the example shown about 20 o .
- the twin wire runs at the right end in the drawing around a rear forming roller 5.
- This forming roller 5 can be designed as a suction roller, as a full roller and / or can be grooved in the circumferential direction.
- the bottom wire 12 carrying the fiber layer leaves this forming roller 5 at a point E, so that the forming zone is formed between the points D and E.
- Below the lower wire 12 there are two formation shoes 22 and 22 'with vacuum boxes in the area of the double guide of the lower wire 12 and the upper wire 18 in this exemplary embodiment. These formation shoes rest with webs 24 spaced apart from one another on the lower wire.
- the screen moves at a high speed. Since the suspension supplied by the nozzle 20 contains up to 99% water in addition to fibers and a filler, violent dewatering takes place in the wrapping area alpha to the effect that a propellant jet A is generated. This driving jet A is thrown off almost tangentially to the forming roller. Since the forming roll is designed as an open forming roll formed with circumferential chambers, a water jet A 'is also formed in the circumferential direction in order to simultaneously drain some of the water downward from the suspension.
- the size of the wrapping of the forming roller significantly influences the force and the amount of water of the jet A, whereby jet thicknesses of 2 to 19 mm can be generated, depending on the web speed of 300 to 2000 m / min.
- the jet makes approx. 40% the amount that is drained in the top sieve alone.
- the driving jet A is directed as the main jet through a guide element 25 and 25 ′, which here consists of two sections, and which covers the entire forming zone by increasing the distance from the forming roller 10 to the twin wire in the direction of the point E. That means in this exemplary embodiment, in which the twin wire in the forming zone also rises slightly, the guide element also initially rises and then falls towards the end again, whereby an essentially horizontal section can also be provided. From the drawing it can be seen that the curvature of the guide element is relatively flat.
- Section 25 'of the guide element can be pivoted upwards about a bearing axis 33 via a rod 31 in order to make the area in which the forming strips are located accessible for cleaning purposes.
- three forming strips 26, 26 'and 26'' are located in the second half of the forming zone, starting approximately from the middle, but preferably in the last third, it also being possible for only two or more strips to be provided .
- These strips rest with their lower end, preferably outside the webs 24, on the top wire and thus on the twin wire.
- the forming strips are followed by guide surfaces 27, 27 ', 27''which are arranged at the angle shown to the screen. This angle is in the range of 20 to 90 o , but preferably in the range of 37 o .
- the propellant jet has so much kinetic energy that the secondary jets B, C and C 'are also detected in the area of the forming strips 26, 26' and 26 '' and are then guided into a deflection trough 30.
- the propellant jet cannot strike the strips directly, which in turn calms the flow conditions and therefore more gently and intensively drains leads in the area of the lasts.
- the number of forming strips is equal to or greater than 2 and the distance is less than 200 mm, a very good effect can be achieved both with regard to the drainage and with regard to the formation of the fiber structure.
- the water discharged through the top sieve is drained off at a point where it is less disturbing and more space is available.
- the forming strips B, C and C ' lie on the top wire and are pressed onto the surface in such a way that the twin wire is deflected, either close to the forming shoe or between the webs 24 the formation shoes 22, 22 '.
- the deflection is up to 10 mm, preferably 4 mm. For this, reference is made to FIG. 2.
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- Inks, Pencil-Leads, Or Crayons (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
Abstract
Description
Die Erfindung bezieht sich auf einen Doppelsiebformer gemäß Oberbegriff des Anspruchs 1.The invention relates to a twin wire former according to the preamble of claim 1.
Ein derartiger Doppelsiebformer ist aus der DE-A-20 51 444 bekannt. Die dort verwendete Formierwalze befindet sich allerdings nicht im Bereich des aus dem Stoffauflauf ankommenden Suspensionsstrahles. Das nach oben abgeschleuderte Wasser wird in einer Wanne aufgefangen und abgebremst.Such a twin wire former is known from DE-A-20 51 444. The forming roller used there, however, is not in the area of the suspension jet arriving from the headbox. The water thrown upwards is collected in a tub and braked.
Einen weiteren Doppelsiebformer, jedoch mit Vorentwässerung, zeigt die DE-OS 31 23 132. Die vordere Formierwalze ist als offene Formierwalze oberhalb des Obersiebes angeordnet und schleudert Wasser schräg nach oben ab, ohne allerdings eine Treibwirkung für Nebenstrahlen hervorzurufen, die im Bereich der Entwässerungsleisten entstehen, da hier die Strahlen mit im wesentlichen gleicher Geschwindigkeit nahezu parallel verlaufen. Am Untersieb liegt in Bewegungsrichtung des Doppelsiebes hinter der Formierwalze eine weitere Formierwalze, der gegenüber ohne Anlage am Obersieb die Entwässerungsleisten angeordnet sind.DE-OS 31 23 132 shows a further twin wire former, but with pre-dewatering. The front forming roller is arranged as an open forming roller above the top wire and throws water diagonally upwards, without however causing a propelling effect for secondary jets which occur in the area of the drainage strips , since here the rays run almost parallel at essentially the same speed. On the lower wire, in the direction of movement of the twin wire, there is another forming roller behind the forming roller, the drainage strips of which are arranged opposite without contacting the upper wire.
Andere Doppelsiebformer, die mit einer oben liegenden vorderen Formierwalze arbeiten und im Bereich des Obersiebes, auf diesem aufliegend Entwässerungsleisten aufweisen, arbeiten mit Saugkästen, die zwischen den Entwässerungsleisten angeordnet sind, um das Wasser seitlich aus der Vorrichtung abzuführen.Other twin-wire formers, which work with an upper front forming roll and in the area of the upper wire, have drainage bars resting thereon, work with suction boxes which are arranged between the drainage bars in order to discharge the water laterally from the device.
Der Erfindung liegt die Aufgabe zugrunde, einen Doppelsiebformer der eingangs genannten Art zu schaffen, bei dem durch einen einfacheren und kompakteren Aufbau eine schonendere und bessere Entwässerung derart innerhalb der Formierzone erzielbar ist, daß ohne eine negative Beeinflussung der Retention der Fasern der Formiervorgang verbessert und insbesondere vergleichmäßigt werden kann.The invention has for its object a twin wire former of the beginning to create the type mentioned, in which a more gentle and better drainage can be achieved within the forming zone in such a way that the formation process can be improved and in particular evened out without a negative influence on the retention of the fibers.
Diese Aufgabe wird erfindungsgemäß durch die im Kennzeichen des Anspruchs 1 genannten Merkmale gelöst.This object is achieved by the features mentioned in the characterizing part of claim 1.
Durch diese Lösung wird im Anschluß an die Formierwalze der dort abgeschleuderte Wasserstrahl störungsfrei und ohne Erfordernis eines Saugkastens entlang dem Wasserleitelement in den Endbereich der Formierzone abgeleitet. Dabei kann dieses Wasserleitelement in Anpassung an die Strömungsverhältnisse optimal, vorzugsweise relativ flach gekrümmt, d.h. angenähert dem Siebverlauf, ausgerichtet sein. Der abgeschleuderte Wasserstrahl hat eine Treibwirkung dahingehend, daß durch die optimale Ausrichtung und die optimale Führung der abgeschleuderte Wasserstrahl als Treibstrahl eine Mitnahmewirkung für die Nebenstrahlen im Bereich der Entwässerungsleisten ausübt. Dies gilt insbesondere dann, wenn im Bereich der Formierleisten für die Wasserabführung ein Energieverlust auftritt. Durch das Abschleudern des Wassers im Bereich der vorderen Formierwalze bei Eingabe einer nicht vorentwässerten Suspension, durch das sich unmittelbar anschließende stationäre Formierelement im Bereich des Untersiebes und die sich dann anschließende Entwässerung im Bereich der Formierleisten erfolgt eine optimal gestaffelte Entwässerung dadurch, daß die Druckimpulse auf die Suspension zwischen den Sieben mit zunehmender Formation gesteigert werden können.As a result of this solution, the water jet thrown off there is discharged without interference and without the need for a suction box along the water guiding element into the end region of the forming zone. In this case, this water guiding element can be optimally, preferably relatively flatly curved, in adaptation to the flow conditions, i.e. approximate the course of the sieve. The thrown-off water jet has a driving effect in that the optimal alignment and the optimal guidance of the thrown-off water jet as driving jet have a driving effect for the secondary jets in the area of the drainage strips. This applies in particular if there is a loss of energy in the area of the molding strips for water drainage. By centrifuging the water in the area of the front forming roller when entering a suspension that has not been pre-dewatered, by the immediately following stationary forming element in the area of the lower wire and then by subsequent dewatering in the area of the forming bars, an optimally staggered dewatering takes place in that the pressure impulses on the Suspension between the sieves can be increased with increasing formation.
Durch die Möglichkeit des Weglassens der Saugkästen ist eine dichtere Staffelung der Formierleisten möglich. Dies bedeutet eine höhere Frequenz der Suspension und dies eine gleichmäßigere Formation.The possibility of omitting the suction boxes enables the formation bars to be staggered more densely. This means a higher frequency of the suspension and a more uniform formation.
Die Formierung wird auch verbessert dadurch, daß die als Formierleisten wirkenden Entwässerungsleisten auf dem Obersieb aufliegen und insbesondere drückend aufliegen, so daß eine Ablenkung des Doppelsiebes erfolgt.The formation is also improved in that the drainage strips, which act as forming strips, rest on the upper sieve and in particular are pressed against them, so that the twin wire is deflected.
Wenn entsprechend einer vorteilhatten Weiterbildung die Formierleisten in der hinteren Hälfte und insbesondere im letzten Drittel der Formierzone angeordnet sind, wird vermieden, daß kurz hinter der Formierwalze der heftige Treibstrahl auf die Formierleisten trifft.If, according to an advantageous development, the forming strips are arranged in the rear half and in particular in the last third of the forming zone, it is avoided that the violent driving jet strikes the forming strips just behind the forming roller.
Von wesentlichem Vorteil für die Erfindung ist die Tatsache, daß die nicht vorentwässerte Suspension dem zusammenlaufenden Doppelsieb zugeführt wird und dann im Umschlingungsbereich des Doppelsiebs um die vordere Formierwalze entwässert und somit ein sehr heftiger Treibstrahl erzeugt wird.An essential advantage for the invention is the fact that the suspension, which has not been pre-dewatered, is fed to the converging twin wire and then dewatered in the loop area of the twin wire around the front forming roller, thus producing a very violent driving jet.
Wenn die Auftragsrichtung der Suspension aus der Auftragsdüse in etwa die Richtung des abgeschleuderten Treibstrahls ist, dann wirkt sich der somit stärkere Treibstrahl vom Anfang an dahingehend aus, die insbesondere beim Anfahren schwachen Nebenstrahlen mitzunehmen. Dies bedeutet, daß stets das im Bereich der Formierleisten anfallende Wasser problemlos mitgerissen wird.If the direction of application of the suspension from the application nozzle is approximately the direction of the propelled jet, then the more powerful propellant from the beginning has the effect of taking along the weak secondary jets, particularly when starting up. This means that the water accumulating in the area of the molding strips is always carried away without any problems.
Der Winkel, mit dem das Doppelsieb die Formierwalze umschlingt, beträgt vorzugsweise 5o bis 120o und insbesondere ca. 20o. Diese Umschlingung beeinflußt die Stärke des Treibstrahles. Die Treibstrahldicken können zwischen 2 bis 19 mm betragen, und zwar je nach der Bahngeschwindigkeit von 300 bis 2000 m/min. Dabei macht normalerweise der Treibstrahl ca. großer gleich 40 % der Menge aus, die allein im Obersieb entwässert wird.The angle at which the twin wire wraps around the forming roller is preferably 5 o to 120 o and in particular approximately 20 o . This wrap affects the strength of the jet. The driving jet thicknesses can be between 2 and 19 mm, depending on the web speed of 300 to 2000 m / min. The driving jet usually makes up about 40% of the amount that is dewatered in the top sieve alone.
Vorzugsweise sind zwei oder drei und insbesondere drei Formierleisten vorgesehen.Preferably two or three and in particular three forming strips are provided.
Die Formierleisten können in Richtung des Siebverlaufes geneigt ausgerichtet sein und nehmen dabei zum Sieb einen Winkel von 20 bis 90o und insbesondere ca. 37o ein. Dies beeinflußt den Übergang der Nebenstrahlen entlang der Formierleisten in den Haupt-Treibstrahl.The forming blades may be oriented inclined towards the Siebverlaufes and take it to the screen an angle of 20 ° to 90 ° and in particular approximately 37 o a. This affects the transition of the secondary jets along the forming strips into the main driving jet.
Vorzugsweise sind die Formierleisten in einem Abstand von weniger als 200 mm angeordnet, um so die beste Wirkung zu erzielen.The forming strips are preferably arranged at a distance of less than 200 mm in order to achieve the best effect.
Das Wasserleitelement als Innenkontur einer Oberwanne kann ausgehend von der Formierwalze zunächst flach ansteigen, dann im wesentlichen horizontal und danach zum Ende der Formierzone wieder abfallend angeordnet sein, wobei dieses Leitelement im ganzen weitgehend flach gekrümmt ist, so daß die Wasserstrahlen durch Zentrifugalkraft als Filmströmung anliegen.The water guiding element as the inner contour of an upper trough can initially rise flat from the forming roller, then be arranged essentially horizontally and then fall again towards the end of the forming zone, this guiding element being largely flat, so that the water jets are applied as a film flow by centrifugal force.
Neben einer schonenden Entwässerung wird insbesondere eine Verbesserung der Formation (Egoutteur-Effekt) erreicht, und zwar ohne die Retention, Nadellöcher und das L/Q-Verhältnis nachteilig zu beeinflussen.In addition to gentle drainage, an improvement in the formation (egoutteur effect) is achieved, without adversely affecting retention, pinholes and the L / Q ratio.
Bei Siebgeschwindigkeiten unter 800 m/min. können zusätzlich Vakuumkästen vorgesehen sein.At screen speeds below 800 m / min. vacuum boxes can also be provided.
Die Formierwalze kann zugleich auch als Saugwalze ausgebildet sein, damit der bei hohen Drehzahlen auftretende geringere Entwässerungsdruck des Außensiebes durch Vakuum kompensiert werden kann.The forming roller can also be designed as a suction roller so that the lower drainage pressure of the outer wire that occurs at high speeds can be compensated for by vacuum.
Die Begriffe "vorne" und "hinten" beziehen sich auf die Laufrichtung der Siebe und insbesondere des Doppelsiebs.The terms "front" and "rear" refer to the running direction of the sieves and in particular the double sieve.
Weitere vorteilhaffe Ausgestaltungen ergeben sich aus den Unteransprüchen.Further advantageous configurations result from the subclaims.
Die Erfindung wird nachfolgend anhand eines in den Zeichnungen rein schematisch dargestellten Ausführungsbeispiels näher erläutert. Es zeigt:
- Fig. 1
- eine schematische Darstellung eines Doppelsiebformers als Teil einer Papierherstellungsmaschine und
- Fig. 2
- eine Teilansicht von auf dem Obersieb drückend aufliegenden Formierleisten.
- Fig. 1
- is a schematic representation of a twin wire former as part of a paper making machine and
- Fig. 2
- a partial view of forming strips pressing on the top wire.
In Fig. 1 links ist schematisch eine Formierwalze 10 dargestellt, und zwar als sog. offene Formierwalze, in deren Umfangsfläche Kammern ausgebildet sind. Über diese Formierwalze wird ein Untersieb 12 einem Suspensions-Beschickungsspalt 14 zugeführt, der von dem um die Formierwalze 10 zugeführten Untersieb 12 und dem von einer Umlenkwalze 16 zugeführten Obersieb 18 gebildet wird, wobei beide Siebe an einer Stelle D zusammentreffen und von dort an ein Doppelsieb bilden. Diesem Beschickungsspalt 14 ist eine Suspensions-Beschickungsdüse 20 zugeordnet.1, a forming
Das Doppelsieb umschlingt bei dem dargestellten Beispiel die Formierwalze 10 mit einem Winkel alpha, der zwischen 5o und 120o, im dargestellten Beispiel ca. 20o beträgt. Das Doppelsieb läuft am rechten Ende in der Zeichnung um eine hintere Formierwalze 5. Diese Formierwalze 5 kann als Saugwalze, als Vollwalze ausgeführt sein und/oder in Umfangsrichtung gerillt sein. Das die Faserschicht tragende Untersieb 12 verläßt diese Formierwalze 5 an einer Stelle E, so daß zwischen den Stellen D und E die Formierzone gebildet wird. Unterhalb des Untersiebs 12 befinden sich im Bereich der Doppelführung von Untersieb 12 und Obersieb 18 bei diesem Ausführungsbeispiel zwei Formationsschuhe 22 und 22' mit Vakuumkästen. Diese Formationsschuhe liegen mit im Abstand zueinander angeordneten Stegen 24 am Untersieb an.In the example shown, the twin wire wraps around the forming
Normalerweise bewegt sich das Sieb mit einer hohen Geschwindigkeit. Da die von der Düse 20 aufgegebene Suspension neben Fasern und einem Füllstoff bis zu 99 % Wasser enthält, erfolgt im Umschlingungsbereich alpha eine heftige Entwässerung dahingehend, daß ein Treibstrahl A erzeugt wird. Dieser Treibstrahl A wird nahezu tangential zur Formierwalze abgeschleudert. Da die Formierwalze als mit Umfangskammern ausgebildete offene Formierwalze ausgebildet ist, wird auch ein Wasserstrahl A' in Umfangsrichtung ausgebildet, um gleichzeitig einen Teil Wasser aus der Suspension nach unten abzuleiten.Usually the screen moves at a high speed. Since the suspension supplied by the
Die Größe der Umschlingung der Formierwalze beeinflußt wesentlich die Kraft und die Wassermenge des Treibstrahls A, wobei Treibstrahldicken von 2 bis 19 mm erzeugt werden können, je nach der Bahngeschwindigkeit von 300 bis 2000 m/min.. Der Treibstrahl macht dabei ca.- 40 % der Menge aus, die allein im Obersieb entwässert wird.The size of the wrapping of the forming roller significantly influences the force and the amount of water of the jet A, whereby jet thicknesses of 2 to 19 mm can be generated, depending on the web speed of 300 to 2000 m / min. The jet makes approx. 40% the amount that is drained in the top sieve alone.
Geleitet wird der Treibstrahl A als Hauptstrahl durch ein hier aus zwei Sektionen bestehendes Leitelement 25 und 25', welches die gesamte Formierzone erfaßt, indem der Abstand ausgehend von der Formierwalze 10 zum Doppelsieb in Richtung zum Punkt E zunimmt. Das heißt in diesem Ausführungsbeispiel, bei dem auch das Doppelsieb in der Formierzone leicht ansteigend verläuft, verläuft auch das Leitelement zunächst ansteigend und dann gegen Ende wieder abfallend, wobei auch ein im wesenltichen horizontaler Abschnitt vorgesehen werden kann. Aus der Zeichnung ist ersichtlich, daß der Krümmungsverlauf des Leitelementes relativ flach ist.The driving jet A is directed as the main jet through a
Die Sektion 25' des Leitelementes ist über eine Stange 31 um eine Lagerachse 33 nach oben schwenkbar, um für Reinigungszwecke den Bereich zugänglich zu machen, in dem sich die Formierleisten befinden.Section 25 'of the guide element can be pivoted upwards about a
Bei der Darstellung in Fig. 1 befinden sich in der zweiten Hälfte der Formierzone, ausgehend etwa von der Mitte, vorzugsweise aber im letzten Drittel, drei Formierleisten 26,26' und 26'', wobei auch gegebenenfalls nur zwei oder mehr Leisten vorgesehen sein können. Diese Leisten liegen mit ihrem unteren Ende, vorzugsweise außerhalb der Stege 24, auf dem Obersieb und somit auf dem Doppelsieb an. An die Formierleisten schließen sich Führungsflächen 27,27',27'' an, die im dargestellten Winkel zum Sieb angeordnet sind. Dieser Winkel liegt im Bereich von 20 bis 90o, vorzugsweise aber im Bereich von 37o.In the illustration in FIG. 1, three forming
Der Treibstrahl weist soviel kinetische Energie auf, daß die Nebenstrahlen B, C und C' im Bereich der Formierleisten 26, 26'und 26'' miterfaßt und anschließend in eine Umlenkwanne 30 geführt werden.The propellant jet has so much kinetic energy that the secondary jets B, C and C 'are also detected in the area of the forming
Dadurch, daß die Formierleisten relativ weit zurückversetzt von der Formierwalze, beispielsweise ab dem Ende des ersten Drittes der Formierzone D-E angeordnet sind, kann der Treibstrahl nicht unmittelbar auf die Leisten prallen, was zu einer Beruhigung der Strömungsverhältnisse und somit zu einer schonenderen und intensiveren Entwässerung insbesondere im Bereich der Leisten führt.Due to the fact that the forming strips are set back relatively far from the forming roller, for example from the end of the first third of the forming zone DE, the propellant jet cannot strike the strips directly, which in turn calms the flow conditions and therefore more gently and intensively drains leads in the area of the lasts.
Wenn die Anzahl der Formierleisten gleich oder größer als 2 ist und der Abstand kleiner als 200 mm, so kann eine sehr gute Wirkung sowohl hinsichtlich der Entwässerung als auch hinsichtlich der Formierung des Fasergefüges erzielt werden. Die Abführung des durch das Obersieb abgeführten Wassers erfolgt an einer Stelle, wo dies weniger störend ist und auch mehr Platz zur Verfügung steht.If the number of forming strips is equal to or greater than 2 and the distance is less than 200 mm, a very good effect can be achieved both with regard to the drainage and with regard to the formation of the fiber structure. The water discharged through the top sieve is drained off at a point where it is less disturbing and more space is available.
Vorzugsweise liegen zur Verbesserung der Formierung des Fasergefüges und der Füllstoffe die Formierleisten B, C und C' auf dem Obersieb auf und werden dabei so auf die Oberfläche gedrückt, daß eine Ablenkung des Doppelsiebes erfolgt, und zwar entweder dicht beim Formierschuh oder zwischen den Stegen 24 der Formierschuhe 22, 22'. Die Ablenkung beträgt bis zu 10 mm, vorzugsweise 4 mm. Hierzu wird auf Fig. 2 verwiesen.To improve the formation of the fiber structure and the fillers, the forming strips B, C and C 'lie on the top wire and are pressed onto the surface in such a way that the twin wire is deflected, either close to the forming shoe or between the
Infolge der Umlenkung des Wassers an den Formierleisten entstehen Geschwindigkeitsverluste, so daß sich eine Geschwindigkeitsdifferenz gemäß Betrag und Richtung zwischen dem Hauptstrahl A und der Nebenstrahlen B, C und C' ergibt. Der dadurch erzeugte Sog unterstützt die Entwässerung, ohne daß bei Siebgeschwindigkeiten über ca. 800 m/min. ein aufwendiges Vakuum angebracht werden müßte. Im Grunde genommen wird somit die kinetische Energie des Hauptstrahles A ausgenutzt, soweit sich eine Geschwindigkeitsdifferenz zwischen diesen und den Nebenstrahlen ergibt.As a result of the deflection of the water on the forming strips, speed losses occur, so that there is a speed difference according to the amount and direction between the main jet A and the secondary jets B, C and C '. The suction generated thereby supports dewatering without the need for sieve speeds above approx. 800 m / min. a complex vacuum would have to be applied. Basically, the kinetic energy of the main beam A is thus used insofar as there is a speed difference between this and the secondary beams.
Es ist wesentlich zu beachten, daß im Formationsbereich der Papiermaschine gestaffelte Einwirkungen auf die Bahn angestrebt werden, derart, daß mit zunehmender Entwässerung die Größe der Druckimpulse zunimmt.It is important to note that in the formation area of the paper machine, gradual effects on the web are sought, in such a way that the size of the pressure pulses increases with increasing drainage.
Claims (17)
- Twin-wire former with- a top wire (18) and a bottom wire (12),- a suspension feed nozzle (20) (for suspension which has not been subjected to preliminary dewatering) which is arranged before the point at which the top wire (18) and the bottom wire (12) meet to form a twin wire,- a forming roll (10) which is arranged below the bottom wire (12) and is in particular open,- the twin wire winding partly around the forming roll (10),- a water guide element (25; 25') which is arranged above the top wire (18) in the area of the forming roll (10),- at least one forming element (22; 22') which bears against the bottom wire (12) and, as a stationary forming element, has a flatter curvature than the forming roll (10) and- at least one dewatering bar (26; 26'; 26'') arranged above the top wire (18) after the forming roll in the direction of movement of the twin wire,characterised in that- the forming roll (10) is disposed at the beginning of the forming zone (D-E) and the water guide element (25; 25') extends approximately from the beginning of the forming zone (D-E),- the forming element (22; 22'), of which there is at least one, bearing against the bottom wire (12) is arranged after the forming roll (10) in the direction of movement of the twin wire,- the dewatering bars (26; 26'; 26'') are forming bars having a forming action and, as such, lie heavily on the top wire (18) and- guiding surfaces (27; 27'; 27'') adjoin the forming bars (26; 26'; 26'') and end at a distance before the water guide element (25; 25').
- Twin-wire former according to claim 1, characterised in that the stationary forming element (22; 22') is formed in a manner which is known per se as a forming shoe with spaced crosspieces (24; 24') which are arranged transversely to the wire path.
- Twin-wire former according to claim 2, characterised in that the forming bars (26; 26'; 26'') lie heavily on the twin wire (12, 18) such that this is deflected.
- Twin-wire former according to claims 1 and 2, characterized in that the forming bars (26; 26'; 26'') lie on the top wire between the crosspieces (24; 24') of the forming shoe.
- Twin-wire former according to claim 4, characterised in that the twin wire (12, 18) winds around the forming roll (10) at a vertical line through the axis of the forming roll (10) in the front half of the forming roll (10).
- Twin-wire former according to one of claims 1 to 5, characterised in that a rear forming roll (5) is arranged at the end of the forming zone (D-E), which roll is also disposed below the bottom wire (12).
- Twin-wire former according to one of claims 1 to 6, characterized in that the twin wire is deflected due to the pressure exerted by the forming bars (26, 26'; 26'') by up to 10 mm, in particular 4 mm.
- Twin-wire former according to one of claims 1 to 7, characterized in that the running-off point (D) of the twin wire (12, 18) from the front forming roll (10) lies in the top, front quadrant, preferably in the angular section between 310° and 360°.
- Twin-wire former according to one of claims 1 to 8, characterized in that the forming bars (26; 26'; 26'') are arranged in the last two thirds, in particular in the last third of the forming zone (D-E).
- Twin-wire former according to one of claims 1 to 9, characterised in that the twin wire (12, 18) winds around the forming roll (10) at an angle (alpha) of 5° to 120°, in particular approximately 20°.
- Twin-wire former according to one of claims 1 to 10, characterised in that two or three forming bars (26; 26'; 26'') are provided.
- Twin-wire former according to claim 1, characterised in that the guiding surfaces (27; 27'; 27'') are inclined in the direction of the wire path, forming an angle of 20 to 90°, in particular approximately 37°, with the wire.
- Twin-wire former according to one of claims 1 to 12, characterised in that the forming bars (26; 26'; 26'') are arranged along the twin wire at spacings of less than 200 mm.
- Twin-wire former according to one of claims 1 to 13, characterised in that the water guide element (25; 25') is arranged such that it firstly rises at a small angle, then extends essentially horizontally and afterwards slopes down again.
- Twin-wire former according to one of claims 1 to 14, characterised in that the water guide element (25; 25') consists of a plurality of sections which can be moved to alter the overall path of the guide surface.
- Twin-wire former according to one of claims 1 to 14, characterised in that a section of the water guide element (25; 25') which covers the forming bars (26, 26', 26'') can be swung away.
- Twin-wire former according to one of claims 1 to 16, characterised in that the forming roll (10) is formed as a suction roll.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3910892A DE3910892A1 (en) | 1989-04-04 | 1989-04-04 | DOUBLE SCREEN FORMER |
| DE3910892 | 1989-04-04 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0391025A1 EP0391025A1 (en) | 1990-10-10 |
| EP0391025B1 true EP0391025B1 (en) | 1994-09-21 |
Family
ID=6377839
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90101039A Expired - Lifetime EP0391025B1 (en) | 1989-04-04 | 1990-01-19 | Twin-wire former |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0391025B1 (en) |
| AT (1) | ATE111990T1 (en) |
| CA (1) | CA2012251A1 (en) |
| DE (1) | DE3910892A1 (en) |
| ES (1) | ES2058612T3 (en) |
| FI (1) | FI900730A0 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI83977C (en) * | 1989-11-06 | 1991-09-25 | Valmet Paper Machinery Inc | Gap formers in paper machine |
| DE4037017C2 (en) * | 1990-11-20 | 1994-12-08 | Escher Wyss Gmbh | Wet part of a twin wire paper machine |
| JP2808491B2 (en) * | 1990-12-19 | 1998-10-08 | 三菱重工業株式会社 | Twin wire former for paper machine |
| FI93032C (en) * | 1991-03-15 | 1995-02-10 | Valmet Paper Machinery Inc | Two-wire web forming section of a paper machine |
| DE4117597A1 (en) * | 1991-05-29 | 1992-12-03 | Voith Gmbh J M | DOUBLE SCREEN FOR A PAPER MACHINE |
| DE10106731A1 (en) * | 2001-02-14 | 2002-08-22 | Voith Paper Patent Gmbh | Twin-wire former for the production of a fibrous web from a fibrous suspension |
| DE102010042604A1 (en) | 2010-10-19 | 2012-04-19 | Voith Patent Gmbh | Sheet forming unit for producing a material web and method for operating the sheet forming unit |
| FI11620U1 (en) * | 2016-12-08 | 2017-04-12 | Valmet Technologies Oy | Viral part, especially modernized viral part |
| CN107460760B (en) * | 2017-09-13 | 2019-03-01 | 长兴恒大电子材料有限公司 | A kind of heat transfer paper production and processing technology |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0296135A2 (en) * | 1987-06-18 | 1988-12-21 | Valmet Paper Machinery Inc. | Hydrid former for a paper machine |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1294075A (en) * | 1969-02-13 | 1972-10-25 | Beloit Corp | Improved forming arrangement |
| BE757784R (en) * | 1969-10-22 | 1971-04-01 | Beloit Corp | IMPROVED FORMING DEVICE |
| SE372300B (en) * | 1970-01-26 | 1974-12-16 | Enso Gutzeit Oy | |
| DE2826158B2 (en) * | 1978-06-15 | 1980-07-24 | J.M. Voith Gmbh, 7920 Heidenheim | Wire section for a machine for the production of fiber webs |
| DE3233724D2 (en) * | 1981-02-28 | 1983-01-13 | Voith Gmbh | Device for continuously dehydrating a fiber web |
| DE3153305C2 (en) * | 1981-09-04 | 1986-10-23 | Sulzer-Escher Wyss GmbH, 7980 Ravensburg | Drainage unit for Fourdrinier paper machines |
| FI75376C (en) * | 1982-04-30 | 1988-06-09 | Valmet Oy | FORMNINGSSKO FOER FORMARE I PAPPERSMASKIN. |
| FI840246A (en) * | 1984-01-20 | 1985-07-21 | Valmet Oy | FOERFARANDE OCH ANORDNING VID FORMNING AV PAPPERSBANA. |
-
1989
- 1989-04-04 DE DE3910892A patent/DE3910892A1/en active Granted
-
1990
- 1990-01-19 ES ES90101039T patent/ES2058612T3/en not_active Expired - Lifetime
- 1990-01-19 AT AT90101039T patent/ATE111990T1/en active
- 1990-01-19 EP EP90101039A patent/EP0391025B1/en not_active Expired - Lifetime
- 1990-02-14 FI FI900730A patent/FI900730A0/en not_active IP Right Cessation
- 1990-03-15 CA CA002012251A patent/CA2012251A1/en not_active Abandoned
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0296135A2 (en) * | 1987-06-18 | 1988-12-21 | Valmet Paper Machinery Inc. | Hydrid former for a paper machine |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2058612T3 (en) | 1994-11-01 |
| DE3910892A1 (en) | 1990-10-11 |
| EP0391025A1 (en) | 1990-10-10 |
| CA2012251A1 (en) | 1990-10-04 |
| ATE111990T1 (en) | 1994-10-15 |
| FI900730A0 (en) | 1990-02-14 |
| DE3910892C2 (en) | 1993-09-09 |
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