WO2013050215A1

WO2013050215A1 - Papermaking fabric

Info

Publication number: WO2013050215A1
Application number: PCT/EP2012/067456
Authority: WO
Inventors: Wolfgang Heger
Original assignee: ANDRITZ KUFFERATH GmbH
Priority date: 2011-10-04
Filing date: 2012-09-06
Publication date: 2013-04-11
Also published as: CN103975106A; ES2575240T3; DE102011054163B3; BR112014008048A2; KR101550664B1; EP2764157A1; EP2764157B1; PT2764157E; CN103975106B; PL2764157T3; US20140345819A1; KR20140082759A; BR112014008048B1; JP5816757B2; JP2014532124A; LT2764157T

Abstract

The invention relates to a papermaking fabric which is designed as a multi-layer woven fabric having an upper fabric layer and a lower fabric layer. The upper fabric layer has a plurality of upper longitudinal threads which run solely in the upper fabric layer and a plurality of upper transverse threads which are interwoven with the upper longitudinal threads and each run at least primarily in the upper fabric layer. The lower fabric layer has a plurality of lower longitudinal threads which run solely in the lower fabric layer and a plurality of lower transverse threads which are interwoven with the lower longitudinal threads and run solely in the lower fabric layer. The upper fabric layer has a repeating upper weave pattern on the upper side thereof which is formed from nine upper longitudinal threads and three upper transverse threads. The three upper transverse threads of the upper weave pattern each have the following course in the upper weave pattern: under a upper longitudinal thread, over the next upper longitudinal thread, under the next upper longitudinal thread, over the next upper longitudinal thread, under the four next successive upper longitudinal threads and over the following upper longitudinal thread, wherein, in the upper weave pattern, the course of the respective upper transverse thread is arranged offset to the course of the adjacent upper transverse thread in the transverse direction by three upper longitudinal threads. At least some of the upper transverse threads in the woven fabric are designed as binding transverse threads which, in order to bind the upper fabric layer to the lower fabric layer, temporarily switch into the lower fabric layer during the course thereof under the four successive to longitudinal threads and there run under at least one lower longitudinal thread.

Description

papermaker

The present invention relates to a multilayered

Papermaking fabric, e.g. a sheet forming sieve one

Paper machine, in particular a batt fabric as used in the process of PapierherStellung in the sheet forming zone of a wet end of a paper machine for dewatering / filtration of a pulp suspension or a paper pulp. Such screens are primarily used for high quality, low paper weight graphic papers and high printability requirements.

These papers can be produced with so-called gap shapers or gap formers at speeds of up to 2000 m / min. High demands are placed on the mechanical stability, the drainage performance, the fiber support, the freedom from marking and the running time of the sieve.

An essential process within papermaking is the formation of the sheet {= sheet formation) by dewatering a pulp suspension or a

Paper pulp by filtration in the sheet forming zone of the wet end of a paper machine using a so-called. Blattbildungssiebes done. Pulp suspension can be a mixture of wood or cellulose fibers suspended in water,

Fillers and chemical auxiliaries are understood.

In order to produce a sheet of paper that is as uniform as possible, it is necessary to reduce the water content of the paper

Increase pulp suspension immediately before sheet formation to about 99% or adjust. This ensures that the fibers can be evenly distributed in the water, which has an advantageous effect on the quality of the sheet to be formed. Within the sheet forming zone, ie during the

Sheet formation process, the water content is reduced by the mentioned fitration process to about 80%. The

Paper fibers and the fillers and auxiliaries remain

evenly distributed in the form of a fiber fleece on the

Paper machine screen back.

While in the past drainage was mainly by a paper machine screen applied to a fourdrinier machine, today twin-wire machines are predominantly used, e.g. in the form of so-called gap former (in English "Gap-Former"), These twin-wire machines are characterized in that the pulp suspension is injected into a gap formed between two paper machine screens, so that the drainage can take place simultaneously through both screens, whereby the Fiitrationsprozess and so that too

Production speed of the paper machine can be significantly accelerated. Today, there are paper machines for paper grades with low basis weights, which with

Speeds of more than 2000 m / min can produce.

The extreme demands on the paper to be produced and the conditions prevailing in the paper machine

require specially designed sheet forming screens, which at the same time have high fiber support, high openness and high mechanical stability. In addition, in the field of graphic papers, in addition a slight tendency to marrow of the tissue is required, that is to say a high level

Uniformity of the sheet forming screen.

In recent years have opted for such

Fields of application proven multilayer paper machine screens, di have two differently shaped sides, which are adapted to the particular application. such Sieves have a paper side formed by the top of a top fabric. The paper page is generally referred to as Sieboberseite and is responsible for the formation of the paper sheet. In addition, these sieves have a running side, which is formed by the underside of a lower fabric. The running side, which can also be referred to as the underside of the screen, comes into contact with the elements of the paper machine. The respective screen side has a machine direction and a transverse direction, wherein under the machine direction (in English MD for "machine direction"} the direction of the paper web and thus the

Direction of the paper machine screen is understood, and wherein the transverse direction (in English CMD for "crcss machine directing"), sometimes also called Querermrieriehtung, rotated in the plane of the paper machine screen by 90 °

Direction is, i. the arranged transversely to the direction of the paper and the screen direction.

Due to the very special construction modern

Paper machine screens can usually be exchanged neither paper and running soap, nor machine and transverse direction, otherwise the functioning of the screen is not or not sufficiently guaranteed. For example, on the running side, the machine direction threads (= longitudinal threads), which realize the circulation of the screen, are protected against wear by clearly protruding or protruding transverse threads. On the paper side, e.g. by providing a

balanced ratio of longitudinal and transverse threads a good storage capacity for the paper fibers are guaranteed. With regard to the fiber support but also with regard to the marking tendency of the wire, the simplest and at the same time oldest basic weave of the textile technology, the so-called

Plain weave, proven. In this bond, whose

Binding repeat (= smallest repetitive unit of the Binding) of exactly two warp threads (usually the warp threads form the longitudinal threads / machine direction threads of the wire) and two weft threads (usually the weft threads form the transverse threads of the wire), the threads become particularly intimate and uniform connected to a tissue. As suitable as the plain weave is for the formation of a paper sheet and thus for the paper side, as little is it usually suitable for the running side, becoming a paper machine screen with a canvas paper side

equipped, it may therefore be advisable, a second, the running side of the screen forming fabric layer below the

Provide plain weave, which is sufficient for the screen

Provides stability and wear potential. A particular challenge is the connection of the two layers (i.e., the paper side forming

Upper fabric with the running side forming lower fabric), u.a. because of the cheap for the paper side

Plain weave has unfavorable conditions for such a layer connection.

In the prior art, different approaches for the connection of two fabric layers are described, of which one approach the use of additional, separate

Bindefäden provides, which in the longitudinal or transverse direction

run. According to this approach, two finished,

fully formed fabric layers over separate,

non-woven binding threads interconnected, which

Bindefäden do not contribute to the structure of the respective fabric layer binding / needed. The two fabric layers consist of longitudinal threads and transverse threads, which run exclusively in the respective fabric layer and thereby the respective

Completely create fabric layer pattern or the respective fabric layer bond. This procedure is e.g.

described in CÄ 1 115 177 AI, where separate binding wefts are used, which bind with warp threads of the upper fabric and warp threads of the lower fabric, and DE 39 28 484 AI, are used in the separate warp threads as connecting threads.

Further examples can be found in DE 42 29 828 A1, WO 93/00472 and EP 0 136 284 A2. The separate binding threads are usually made thinner than the respective ones

Fabric ply forming yarns (see, for example, CA 1 115 177 Ai), since the binder yarns are in addition to the yarns. fabric-forming threads must be entered into the fabric structure, which, especially in a plain weave little space for such separate

Binding threads is present. Otherwise, would by the

Bindefäden the originally homogeneous structure of the bond are disturbed, so that especially in the provided on the paper side plain weave stains would arise that cause marks in the paper. In practice, however, it has been shown that the thin binding threads are mainly used for

Paper machines which process a high proportion of abrasive fillers or whose construction greatly aggravate the screens

Bending in the machine direction loaded, quite fast

Wear and break, so that move in the episode, the two layers of fabric first and later separate.

Of course, can not produce high quality paper with such a modified fabric / sieve. An alternative to this is the use of

The threads used for the layer connection serve on the one hand to connect the layers, for which they change between the layers back and forth, and on the other hand form the upper fabric or the

Lower tissue with out. Various inherent threads can be used as connecting threads, i. Transverse and / or longitudinal threads of the upper fabric and / or the lower fabric, wherein the different binding threads different

Sieve properties bring with it. Furthermore, it is known to use two transverse threads, which cooperate as a so-called. Functional transverse thread pair. One or both of the transverse threads of a functional pair run alternately in the upper and lower tissues. The two transverse threads of a functional pair can be a virtual

continuous transverse thread of a Papierseit igen

Form plain weave, i. an upper composite transverse thread. Those thread sections of the functional pair that are not just virtual for the formation of paper-side

continuous transverse thread are needed, run inside the fabric and can be used to attach the lower fabric to the upper fabric. It can the the

Under weave tying thread section e.g. at the same time complete the U tergewebe or its binding. Z two active transverse thread pairs may be e.g. an upper transverse thread which exclusively supports the plain weave (i.e., which runs only in the upper fabric) but has no binding function. Embodiments for this

An approach can be found, for example, in EP 0 097 966 A2, EP 194 283 Al, WO 99/06630 Al, WO 99/06632 Al and WO 02/14601 Al.

Alternatively, the compound of the layers by so-called.

functional longitudinal thread pairs done. Reference may be made by way of example to EP 0 069 101 and EP 093 096, which show a layer connection via functional longitudinal thread pairs.

Object of the present invention is a

Sheet forming screen made of a multi-layered fabric

to provide, at least partially, esp. Fully meet the requirements described above, i. e.g. a high fiber support, a low tendency to march, a suitable mechanical stability and a stable

Having layer connection. To solve this problem, the invention a

Papermaking fabric according to claim 1 ready. Further

Embodiments of the inventive sieve are described in the dependent claims.

The sieve according to the invention is of a

Oberquerfadengebundenen, esp.

made of multi-layered fabric, so from a multilayered

Fabric whose upper layer (preferably exclusively) is connected by means of upper transverse threads with the lower layer. The fabric used for the sieve thus belongs to the group of tissues whose layers are connected by means of tissue-own threads. The connecting upper transverse threads contribute on the one hand to the layer connection and on the other hand to the completion / formation of the upper fabric layer or its binding.

The sieve according to the invention has on the paper side a high fineness to ensure a convenient

Fiber support. Due to the uniform design of the paper side, the tendency to mark is low. The running side can be a ggü. the paper side increased openness for a good drainage behavior and a reduced tendency to

Clogging of the tissue with fibers and impurities. The running side has a high in particular

mechanical stability against stretching. The inner wear and ultimately a ply separation can be in the multilayer

Sheet forming screen, the fabric layers are connected by upper transverse threads together, avoided or greatly reduced.

Therefore, according to the invention, a fine fabric having a very homogeneous design can be used for sheet formation and tied to a stable and coarser lower fabric. The

Upper fabric is made in a binding that is comparable to a plain weave and thus optimal for S

Production of graphic paper is suitable. The

Lower tissue is especially coarser in the longitudinal and transverse directions and thus offers the following advantages: any solids that have penetrated into the tissue through the upper tissue are not retained in the lower tissue; the drainage performance of the screen is determined solely by the paper side; the lower tissue is so open that its influence on the

Total flow is subordinate. The coarse lower tissue is used in particular for the overall sieve

mechanical stability and wear resistance and

Optimize fabric thickness.

According to the paper thus tige tissue is thus constructed relatively fine and homogeneous. The running side fabric layer can be made more robust and with higher openness, esp. With relatively thick wetting and weft threads, which contribute to a higher mechanical strength. It is a stable

Connection of upper and lower tissue by a special formation of paper-side transverse threads with a binding zone before. As a result, depending on the application, a convenient binding frequency can be set.

The papermaker's fabric according to the invention has an upper fabric layer formed of a plurality of upper longitudinal yarns extending exclusively in the upper fabric layer and a plurality of upper transverse yarns interwoven with the upper longitudinal yarns and either completely or predominantly in the upper fabric layer

run. The interwoven upper transverse threads and upper longitudinal threads together form an upper binding, i. an overlapping pattern of the upper fabric layer.

Character istisch for this upper binding is the upper one

Binding repeat (see below), a repetitive pattern on the paper side, which shows the course of the upper transverse threads with respect to the upper longitudinal threads. The papermaking fabric according to the invention further has a lower fabric layer, which consists of a plurality of lower

Longitudinal threads which extend exclusively in the lower fabric layer, and a plurality of lower transverse threads is formed, which are interwoven with the lower longitudinal threads, and extend exclusively in the lower fabric layer. The ver together lower transverse threads and lower

Longitudinal threads together form a lower binding, i. an overlapping pattern of the lower fabric layer, characteristic of this lower binding is the lower weave repeat, a repetitive pattern on the running side.

The lower longitudinal threads may have a larger diameter than the upper longitudinal threads, and the lower transverse threads may have a larger diameter than the upper

Cross threads. The coming into contact with the Papie machine bottom of the screen can be made robust, whereas the coming into contact with the fiber suspension top of the screen can be formed finely. Since the lower longitudinal threads and the lower transverse threads do not change to the upper layer, the fine paper side is not disturbed by the robust lower threads. The comparatively thin upper transverse threads, which change to the lower layer, disturb the lower binding only slightly. Furthermore, the comparatively thick underneath transverse threads protrude further downwardly than the upper transverse threads during their stay in the lower layer, whereby the upper transverse threads are shielded from the lower transverse threads.

The ratio of upper longitudinal threads to lower longitudinal threads in the entire fabric is eg greater than or equal to 1, eg greater than 1. For example, the ratio may be 3 to 2 or alternatively 1 to 1. In this case, the ratio of 3 to 2, which is the formation of a fine upper side and a coarse lower side, is preferred favored. In addition, with this ratio, the lower transverse threads are made particularly thick, while still a sufficiently open bottom can be achieved.

The tissue may e.g. a repetitive one

Have overall repeat in which the ratio of upper

Longitudinal threads to lower longitudinal threads 9 to 6 or 9 to 9

The ratio of upper transverse threads to lower transverse threads in the entire fabric may be e.g. greater than 1, e.g. 2 to 1. This also favors the formation of a fine top and a coarse bottom.

The tissue may e.g. a repetitive one

Have overall repeat in which. the ratio of upper

Cross threads to lower transverse threads 6 to 3 or 12 to 6.

The tissue may e.g. a repetitive one

Have overall repeat in which the ratio of upper

Longitudinal threads to upper transverse threads 9 to 12 or 9 to 9 or 9 to 6. This represents in each case a balanced ratio of upper longitudinal threads to upper transverse threads, with which a fine upper side can be formed. The respective upper weave repeat has nine upper longitudinal threads and three upper transverse threads according to the invention. Each of the three upper transverse threads of each upper weave repeat has the following course: under one upper longitudinal thread, over the next upper longitudinal thread, under the next upper longitudinal thread, over the next upper longitudinal thread, under the four next, successive upper longitudinal thread and over the next upper one In this case, the course (or the starting point thereof) of the respective upper transverse thread relative to the course of the adjacent upper transverse thread in the transverse direction is offset by three upper longitudinal threads. The upper transverse threads repeat the course described in the transverse direction continuously and immediately successive, so that the respective upper transverse thread is interwoven with the upper longitudinal threads of the fabric in the manner of a plain weave, with a so-called. Regularly formed. Zone in which the upper transverse thread between the Fabric layers or in the lower fabric layer runs, depending on whether it is designed as a connecting upper transverse thread or not. The respective binding zone extends over a distance of four upper

Longitudinal threads, and between two adjacent binding zones of an upper transverse thread five upper longitudinal threads are arranged.

For joining the layers, at least some of the upper transverse threads are in the fabric as connecting transverse threads

educated. For this purpose, the upper transverse threads have a so-called.

Binding zone, which is formed by the thread portion which extends below the four upper longitudinal threads. to

Connecting the upper fabric layer to the lower fabric layer may cause some or all of the upper transverse threads during their operation

Gradually under the four consecutive upper

Longitudinal threads, ie in the binding zone, temporarily change to the lower fabric layer and there at least one lower layer

Undercut longitudinal thread, thereby connecting the lower longitudinal thread and thus the lower tissue to the upper tissue.

In the respective overall repeat of the tissue (himself

Repeating weave pattern of the entire fabric, formed from upper longitudinal and transverse threads and lower longitudinal and

Cross threads) should therefore be formed as connecting transverse thread at least one of the upper transverse threads. Such a connecting upper transverse thread binds along its

Through the fabric in the transverse direction repeated (in each binding zone) one or more lower longitudinal threads to the upper Fabric layer, whereby the two layers are connected,

For example, can in the respective total repeat of the tissue, each lower longitudinal thread at least once to the upper

Fabric layer be connected, so for example 5) or exactly twice (see the second embodiment according to FIG. 6), whereby each connection can be made by a separate upper transverse thread, in that in the respective overall repeat of the

Tissue is connected by means of the upper transverse threads of each lower longitudinal thread at least once to the upper fabric layer, a stable layer connection and thus a long lifetime of the screen can be achieved.

But there may also be upper Bindungsrapporte whose upper transverse threads are all formed as non-connecting upper transverse threads. This reduces

however, the number of layer connections, in the respective overall repeat.

For many applications, it may be preferred that at least one of the three upper transverse threads of each upper weave repeat is formed as a connecting transverse thread. More preferably, at least two, in particular each of the three upper transverse threads of each upper weave repeat are formed as connecting transverse thread.

The number of layer joints in each

Overall repeat can be set appropriately depending on the need or application.

The respective connecting upper transverse thread can for

Connecting the upper fabric layer with the lower fabric layer during its course among the four consecutive Upper longitudinal threads undercut exactly one lower longitudinal thread or exactly two consecutive lower longitudinal threads.

The combination of upper fabric layer and lower one

Fabric layer can be done exclusively with the above connecting upper transverse threads. That is, there will be no separate binding threads for the integrity of the fabric

needed. The upper fabric layer can therefore exclusively from a

Variety of adjacent upper Bindungs apporten consist. In other words, in this case no further threads are arranged between the individual upper binding briefs. Also, the respective upper binding repeat can consist exclusively of the nine upper longitudinal threads and the three upper transverse threads.

The lower transverse threads can be so with the lower

Longitudinal threads are interwoven that they form a dreischäftige or sechschäftige binding in the lower fabric layer, in which the course of the respective lower transverse thread after three or six lower longitudinal threads constantly repeated. These are examples, each with a rough and open

Running side can be achieved. The respective lower transverse thread can be used in the three-shed binding e.g. run first over a lower longitudinal thread and then under the two subsequent lower longitudinal threads, and the respective lower

Cross thread may be at the sixfold binding e.g. first over a lower longitudinal thread and then under the five

subsequent lower longitudinal threads run. If the respective overall repeat has nine lower longitudinal threads, then the lower fabric layer can be designed, for example, as three-stitched or neo-strong. The longitudinal threads are preferred as warp threads and the

Cross threads formed as weft threads.

Further variations of the inventive sieve will become apparent from the following description of exemplary

Embodiments.

In the following, some terms used in this application are defined;

As longitudinal yarns threads of the screen / fabric are referred to, which extend in the longitudinal direction or longitudinal extent of the screen and are arranged in operation in the running direction of the paper machine. In the flat-woven sieve, the longitudinal threads are formed by the warp threads of the loom, whereas round weaves are

realize the longitudinal threads with the shots.

As transverse threads, threads of the screen / fabric are referred to, which extend in the transverse direction of the screen and are arranged transversely to the running direction of the paper machine during operation. In the flat woven screen, the transverse threads are formed by the shots. Round fabrics, on the other hand, realize the transverse threads with the chains of the loom.

The fabric layer is understood to be a single-layer fabric consisting of interwoven transverse threads and longitudinal thread (or chains and wefts).

The upper fabric or the upper fabric layer is a usually very finely formed fabric layer, from the i.d.R. the paper side (= outward facing, upper side of the

Upper fabric) of the sieve on which the

Paper fiber layer is formed. The upper fabric is on the "logical top" of the screen. The lower fabric or the lower fabric layer is usually a particularly robust trained fabric layer, of which usually the running side (= outwardly facing, lower side of the

Sub-fabric) of the screen, which comes into direct contact with the wear generating drive and

Dewatering elements of the paper machine.

Upper longitudinal threads are such threads that are themselves

exclusively in the upper fabric and there with in the

Upper fabric extending transverse threads are interwoven. Upper

Longitudinal threads never leave the upper fabric, i. they do not change into the tissue of the web.

Upper transverse threads are threads that are at least predominantly in the upper fabric and are interwoven there with the upper longitudinal threads. Upper transverse threads in the sense of this

Registration can be either exclusively in the

Upper tissues run or temporarily change into the lower tissue. At least a part of the upper transverse threads changes into the lower tissue in order to bind it to the upper tissue.

Lower longitudinal threads are such threads that are themselves

exclusively in the lower fabric and there with in

Sub-woven transverse threads are interwoven. Lower

Longitudinal threads never leave the lower tissue, i. they do not change into the upper tissue.

Lower transverse threads are such threads, which are themselves

exclusively in the lower fabric and there with the

interwoven lower longitudinal threads. Lower transverse threads never leave the lower tissue, i. they do not change into that

Upper tissue.

The weave repeat of the upper weave or the so-called upper weave repeat is a recurrent pattern or one of itself repeating unit in the upper fabric of interwoven upper longitudinal threads and upper transverse threads,

especially the smallest repetitive unit in the upper tissue. In plan view of the upper fabric or the

Paper side of the screen are a variety of such upper ones

Bindungsrapporte in the longitudinal and transverse direction of the screen to recognize and esp. in the transverse direction (but preferably also in the longitudinal direction) immediately lined up. The upper weave repeat therefore represents in particular the recurring overlapping pattern of the upper fabric formed by the upper longitudinal threads and upper transverse threads in the plan view of the upper fabric. If one of the upper transverse threads temporarily changes into the lower fabric, then the exact course of the upper fabric has changed

Transverse thread in the lower tissue on the upper Bindungsrapport no effect; because the upper transverse thread verlä ft during this time always below the upper longitudinal threads. In other words, the upper weave repeat relates to the course of the upper transverse threads with respect to the upper longitudinal threads and the resulting overlapping pattern; The course of the upper transverse threads with respect to the lower longitudinal threads has no significance for the determination of the upper binding repeat.

Analogously, a binding repeat of the lower tissue or a so-called lower binding repeat can be defined / specified.

The overall repeat of the fabric is a recurrent weave pattern / overlap pattern of the entire fabric, especially the smallest repeating egg of the entire fabric, taking into account the course of all the threads (upper and lower longitudinal threads, upper and lower transverse threads). With knowledge of Gesamtrapport3 therefore the entire fabric or sieve can be made. That is, the screen or fabric may be made of a plurality of directly juxtaposed ones

Consist overall reports. A longitudinal thread repeat is the smallest repetitive unit of longitudinal threads in the entire fabric.

Analogously, a transverse thread repeat means the smallest repeating unit of transverse threads in the entire fabric.

In the following the invention will be explained in more detail with reference to various embodiments with reference to the drawing. In the drawing show;

1 is a plan view of a complete upper binding repeat of a sieve according to the invention in a schematic representation,

Fig. 2 is a photograph showing an enlarged view of a section of the paper side of a sieve according to the invention, which consists of a plurality of mutually angre Zenden upper Bindungsrapporten, i. a plan view of the top of a sieve according to the invention or its

upper / paper-side fabric layer, wherein the lower / running side Gewebeiage for reasons of clarity

was omitted / cut away,

FIG. 3 shows the photograph from FIG. 2, with a single upper bond repeat (solid lines) and the eight surrounding upper binding replicas (dashed lines) highlighted, FIG.

Fig. 4 shows various alternative courses for the three upper transverse threads of the upper weave repeat of Fig. 1 within the entire fabric, i. with regard to the upper and lower fabric layer / longitudinal threads,

Fig. 5 shows the total repeat of a sieve according to a first embodiment of the invention in a schematic representation and Fig. 6 shows the total repeat of a sieve according to a second embodiment of the invention in a schematic representation. Fig. 1 shows a complete upper binding repeat of a sieve according to the invention in a schematic representation

View from above. This upper bond repeat repeats on the sieve top, i. the Sieboberseite has a

Plurality of such identically formed upper

Binding reports on.

As shown in Figures 2 and 3, the paper side of a screen according to the invention may e.g. consist of a plurality of such upper binding repeats, which are arranged directly adjacent to each other. That is, to that in Fig. 1

are shown on the upper binding repeats

Paper side of the screen then eight immediately adjacent identically formed upper binding repeats arranged (at the four corners and above, below, right and left).

In FIGS. 1 to 3, the longitudinal threads extend vertically and the transverse threads horizontally.

The upper weave repeat consists of 9 longitudinal threads (1, 2, 3, 9) and 3 transverse threads (21, 22, 23). In FIG. 3, the

Longitudinal threads and transverse threads of an adjacent repeat provided with one or two " ^% ".

In Figure 1, as is common in textile technology, each square represents an intersection of a longitudinal thread (e.g.

Warp thread) and a transverse thread (for example weft thread). If the square is provided with a cross, the longitudinal thread runs over the transverse thread or the transverse thread runs under the longitudinal thread,

otherwise the longitudinal thread runs under the transverse thread. In 3, the circle indicates that the longitudinal thread runs under the transverse thread or the transverse thread over the longitudinal thread.

As shown in Fig. 1, in the upper one

Binding repeat the courses of the three upper transverse threads 21-23 with respect to the nine upper longitudinal threads 1-9 basically the same. In particular, each upper transverse thread 21-23 passes first under an upper longitudinal thread, then over the next upper longitudinal thread, then under the next upper longitudinal thread, then over the next upper longitudinal thread, then below four consecutive upper longitudinal threads and finally over the next upper longitudinal thread.

For example, the upper transverse thread 21 i Fig. 1 initially under the upper longitudinal thread 1, then over the upper longitudinal thread 2, then below the upper longitudinal thread 3, then over the upper longitudinal thread 4, then below the four successive upper longitudinal threads 5 to 8 and finally over the upper longitudinal thread 9. Subsequently, the transverse thread 21 repeats this course. That in which the upper weave repeat not shown in FIG. 1 immediately to the right of the upper weave repeat shown, the upper transverse thread 21 repeats

described course, etc .; see in particular the figure 3. The upper transverse thread 22 has the same course, however, its course or the starting point thereof is shifted relative to that of the upper transverse thread 21 by three upper longitudinal threads to the right. Thus, the course described above begins (once under, once over, once under, once over, sometimes over, once over) for the upper transverse thread 22 at the upper longitudinal thread 4, ie, the upper transverse thread 22 initially runs under the upper longitudinal thread 4. then over the upper longitudinal thread 5, then under the upper longitudinal thread 6, then over the upper longitudinal thread 7, then below the four

successive upper longitudinal threads 8, 9, 1, 2 and finally, above the upper longitudinal thread 3. It is noted that in the texti I technique for determining the threadline in a repeat "over edge / corner" is counted

insofar justified, since the rapport shown in

Transverse another rapport immediately adjacent.

Also, the upper transverse thread 23 has the above-described course {once under, once over it, once under it, once over it, 4 times under, once over it), but its course is shifted relative to the adjacent upper transverse thread 22 by three upper longitudinal threads to the right. Thus, the Ve described above starts for the upper transverse thread 23 at the upper longitudinal thread 7, ie, the upper transverse thread 23 extends first under the upper longitudinal thread 7, then over the upper longitudinal thread 8, then below the upper longitudinal thread 9, then above the upper Longitudinal thread 1, then below the four

successive upper longitudinal threads 2 to 5 and finally over the upper longitudinal thread. 6

In summary, in the upper weave repeat, the course of the respective upper transverse thread relative to the course of the adjacent upper transverse thread is transversely offset by three upper longitudinal threads, which is usually referred to as a gradient in texturing technology. that is,

According to the invention, the pitch of the upper transverse threads in the upper binding repeat or on the paper side is three.

As already explained, the .paper side of the

Siebs invention from a variety of upper

Bindungsrapporten formed in FIG. 1. This is illustrated by FIG. 2 and in particular FIG. 3, in which one of the upper binding repeats is identified by a rectangle of solid lines. The eight upper bond repeats immediately adjacent to this upper bond repeat are shown with dashed rectangles, with six of the eight adjacent upper Bindungsrapporte in Fig. 2 and 3 are shown only partially. Unlike the "X" in FIG. 1, the "o" in FIG. 3 indicates that the upper transverse thread overflows the upper longitudinal thread (or that the upper one is overflowing)

Longitudinal thread running under the upper cross thread).

As can also be clearly seen in FIGS. 2 and 3, the upper longitudinal threads are arranged next to one another substantially parallel to one another and at a distance from one another. The upper transverse threads are also arranged side by side substantially parallel to each other, so do not form functional pairs. The upper transverse threads can in principle also be arranged at a distance from each other, however

touch in sections.

According to the invention, at least some of the upper transverse threads are formed as connecting transverse threads in the fabric.

Connecting transverse threads serve to connect the upper

Fabric layer with the lower fabric part. According to the invention, this connection takes place during the course of an upper transverse thread below the four successive upper longitudinal threads. The upper transverse thread transitions temporarily into the lower fabric layer in order to undermine there or more e lower longitudinal threads and thereby bind to the upper fabric.

In other words, the sieve according to the invention is a so-called. Weft-bound or cross-thread-bonded multilayer fabric, esp. a purely Schussgebundenes or Querfadengebundenes

Multilayer fabric, i. a fabric without further connecting threads.

FIG. 4 shows alternative embodiments or courses of the upper transverse threads 21 to 23 from FIG. 1 within the entire fabric - i. in terms of upper and lower

Fabric layer. Shown is the course of an upper one Transverse thread over a distance of nine upper longitudinal threads; the respective course is repeated in the tissue in

Transverse direction constantly and immediately, i. the transverse thread 21 is e.g. formed from a plurality of immediately successive thread sections, which in each case the course 21a or alternatively in each case the course 21b or alternatively in each case the. Course 21c or alternatively in each case the course 21d

correspond . The courses of the threads 21a to 21d with respect to the upper fabric or with respect to the upper longitudinal threads are identical and correspond to the above-described course of the thread 21 {incl. the starting point). Analogously, the course of the threads 22a to 22d with respect to the upper fabric corresponds to the course of the thread 22, etc.

With the index "a" marked threads are formed as pure upper transverse threads, which run exclusively in the upper fabric and do not contribute to a layer connection.

The threads marked with the index "b," c "or" d ", on the other hand, are formed as connecting transverse threads, which contribute to a connection of the layers.

The threads with the index "b ^M and" c "bind within a so-called binding zone, which is formed by the cross-thread section running under the four successive upper longitudinal threads, exactly one lower longitudinal thread on the upper fabric layer or undercut this Index "b ^w bind in the transverse direction - viewed from left to right - with the respective first lower longitudinal thread 13, 15 and 11. That is, these threads change in the binding zone immediately down to the lower fabric layer to the first possible lower longitudinal thread The threads with the index "c" on the other hand, they bind in the transverse direction - viewed from left to right - with the respective second lower longitudinal thread 14, 10 or 12, ie, these threads overflow the first possible lower longitudinal thread and only bind the subsequent lower longitudinal thread to the upper fabric.

The threads with the index "d" bind within the binding zone exactly two lower longitudinal threads on the upper fabric layer or undercut them.

For a respective upper binding repeat or for three longitudinally adjacent upper transverse threads, the upper transverse thread courses shown in FIG. 4 can be arbitrary

be combined with each other as long as from each group exactly one thread is selected, i. it can be any thread from the first group (21a-21d) with any thread of the second group (22 a - 22 d) and any thread of

third group (23a-23d) are combined. For example, 3 or three longitudinally adjacent upper transverse threads from FIG. 3 may be formed from the threads 21c, 22c, 23c, or from the threads 21b, 22b, 23b, or from the threads 21a, 22a, 23a (so it is also possible that one or more upper binding repeats, but not all, exclusively of non-connecting upper

Transverse threads are formed), or from the threads 21a, 22b, 23c,

As already mentioned, according to the invention in the fabric at least some of the upper transverse threads are connected as connecting

Transverse threads formed. Thus, at least some of the upper binding repeats, e.g. all upper binding repeats, one or more connecting upper transverse threads "b", "c" or "d".

In the respective overall repeat, the respective upper binding repeat can thus be put together arbitrarily, as long as from each group "21", "22", "23" exactly one thread is selected, wherein the upper binding repeats can be composed differently {see eg Figures 5 and 6), and wherein at least one of the upper binding repeats

has at least one connecting upper transverse thread, so that in the tissue a plurality of connecting threads or .. in the

Overall repeat of the tissue at least one connecting thread is present. Against this background, two exemplary embodiments of the invention will now be described.

In the following, the overall repeat (ie a complete weave repeat of the fabric) of a sieve according to a first embodiment of the invention will be described with reference to FIG. A sieve according to the invention can thus be produced by juxtaposing a plurality of such total repeats or consisting of a plurality of such total repeats.

The overall repeat shown in FIG. 5 has nine upper longitudinal threads 1-9 and six lower longitudinal threads 10-15, which are here each designed as warp threads and run exclusively in the upper or the lower fabric layer. The upper warp threads 1-9 are thinner than the lower ones

Warp threads 10-15. The warp or longitudinal ratio of

Paper side / upper fabric to running side / üntergewebe in the

Accordingly, the total repeat and in the fabric is 9 to 6 and 3 to 2, respectively. Furthermore, the overall repeat shown in FIG. 5 has twelve upper transverse threads 21 to 23 and six lower transverse threads 31 to 36. The transverse threads are each formed here as weft threads. The lower transverse threads 31-36 run exclusively in the lower fabric layer. The upper transverse threads change between the two layers of fabric, so they are all as connecting transverse threads formed, however, run

predominantly in the upper fabric layer and form there together with the upper longitudinal threads of the upper fabric and its binding. The upper weft threads are thinner than the lower weft threads 31-36, the shot or

Cross thread ratio of paper side / upper fabric too

frequent side / lower tissue in the Gesaratrapport and in the tissue is therefore 12 to 6 and 2 to 1, respectively.

In the overall repeat, each upper transverse thread 21-23 with respect to the upper longitudinal threads 1-9 has the reference to FIG. 1

described course of once under, once over it, once under it, once over it, 4 times under it, once over it.

The transverse thread pitch in the overall repeat is three. The respective transverse thread course is repeated in the tissue in the transverse direction constantly. In the tissue, each forms upper

Cross thread along with the upper longitudinal threads on the

Paper side therefore a plain weave (once under, once over it, etc.), the along each top transverse thread repeatedly in sections along a distance of four upper longitudinal threads to form a binding zone

is interrupted.

In the overall repeat, the twelve upper transverse threads together with the nine upper longitudinal threads form four upper

Binding repeats a-e, d-f, g-i, j-1. The top three

Transverse threads 21, 22, 23 of the upper weave repeat ac and the three upper transverse ^threads' 21, 22, 23 of the upper weave repeat gi are each as "b" - formed filaments, soft the first of two lower longitudinal yarn in their bonding zone

undermined and thereby connect to the Qbergewebe. The three upper transverse threads 21, 22, 23 of the upper binding repeat d-f and the three upper transverse threads 21, 22, 23 of the upper

Binding replicas jk are each designed as "c" threads, which undercut in their binding zone the second of two lower longitudinal thread and thereby bind to the upper fabric.

The course of the transverse threads in the fabric section af is identical to the course of the transverse threads in the fabric section gi. The twelve upper transverse threads ^' form z together with the new upper longitudinal threads so two upper Querfadenrapporte af, g-1. According to the first embodiment, the six lower form

Cross threads 31-36 together with the six lower longitudinal threads 10 to 15 a relatively open and coarse üntergewebe or a relatively open and rough running side. The six lower transverse threads 31-36 and the six lower longitudinal threads 10 to 15 form the total repeat exactly one lower

Binding repeat off. In the lower weave repeat each lower transverse thread undermines five consecutive lower

Longitudinal threads and then overflows a lower one

Longitudinal thread; see, e.g. the lower longitudinal thread 36. Each lower transverse thread overflows another lower longitudinal thread. The üntergewebe is here in the transverse direction so 6-busts

formed, i. the course of the respective lower

Cross thread repeats after six longitudinal threads. In the embodiment shown in Figure 5, the

Lower tissue tethered to the upper tissue twelve times within a total repeat, by each upper transverse thread once. Each lower longitudinal thread is tied twice, namely by two different upper transverse threads. Because the top

Cross threads are made thinner here than the lower ones

Cross threads, the lower binding (or the overlapping pattern formed by the lower transverse and longitudinal threads) of the temporarily submerged in the lower tissue upper

Cross threads not significantly disturbed. In addition, the lower transverse threads shield the upper transverse threads. It can be so at the same time form a stable layer connection and a fine, homogeneous paper side.

In the following, the overall repeat of a sieve according to a second embodiment of the invention will be described with reference to FIG. An inventive sieve can from a

There are a majority of such total reports.

The Gesaratrapport shown in Figure 6 has nine upper longitudinal threads 1-9 and six lower longitudinal threads 10-15, which are each formed as warp threads and extend exclusively in the upper and the lower fabric layer. The upper longitudinal threads 1-9 are thinner than the lower ones

Longitudinal threads 10-15. The Kett- or Längstadenverhältnis of upper tissue to üntergewebe in the total repeat and in the tissue is thus again 9 to 6 or 3 to 2.

Furthermore, the total repeat shown in FIG. 6 has six upper transverse threads 21-23 and three lower transverse threads 41-43. The transverse threads are again formed as weft threads. The lower transverse threads 41-43 run exclusively in the lower

Fabric layer. The upper transverse threads each change between the two fabric layers, ie they are all formed as connecting transverse threads, but in each case extend predominantly in the upper fabric layer. The upper transverse threads are thinner

formed as the lower transverse threads 41-43. The weft or transverse thread ratio of paper side to outer fabric in the total repeat and in the fabric is 6 to 3 and 2 to 1, respectively.

Each upper transverse thread 21-23 has respect. the upper one

Longitudinal threads 1-9 the described with reference to Figure 1 course of once under, once over it, once under it, once over it, 4 times under it, once over it. The transverse thread pitch in the Gesamt apport or in the tissue is again three. The six upper transverse threads together with the nine upper longitudinal threads in the Gesamtrapport two upper

Binding repeats a-c, d-f. The three upper transverse threads 21, 22, 23 of the upper weave repeat a-c are each formed as "b" yarns, and the three upper transverse yarns 21, 22, 23 of the upper weave repeat d-f are each formed as "c" yarns.

According to the second embodiment, the three lower transverse threads 41-43, together with the six lower longitudinal threads 10 to 15, form a relatively open and coarse lower part. The three lower transverse threads 41-43 and the six lower longitudinal threads 10 to 15 form exactly one lower weave repeat in the overall repeat. In the lower binding repeat, each lower transverse thread initially underwent two successive lower longitudinal threads, then overflows a lower longitudinal thread, again undergoing two successive lower longitudinal threads, and then overflows a lower longitudinal thread; see, e.g. The lower longitudinal thread 42, Each lower transverse thread overflows two other lower longitudinal threads, so that each lower longitudinal thread is overrun in the lower binding repeat of a lower transverse thread. The lower fabric is transversely 3- formed here, i. the course of the respective lower transverse thread is repeated after three longitudinal threads.

In the Ausführungsbei game shown in ^' Figure 6, the lower fabric within the total rappo ts six times to the

Upper fabric tethered, by each upper transverse thread once. Each lower longitudinal thread is once connected in the total apport. Even with the overall repeat according to FIG. 6, a stable layer connection and a fine, homogeneous paper side can be achieved at the same time. With the screen according to the invention, for example a screen with a total repeat according to FIG. 5 or FIG. 6, numerous advantageous properties are achieved or at least made possible, inter alia, the following properties:

• a high degree of fineness of the paper side to ensure appropriate or high fiber support;

• a high uniformity of the paper side to the

Reduction of the tendency of the sieve to change;

• a high openness side for good drainage and reduced tendency of the fabric to clog

Fibers and impurities;

A running side with a high mechanical stability, e.g. against stretching; · Avoidance or reduction of internal wear, whereby a separation of the layers can be avoided / delayed so that the lifetime of the screen is high.

In other words, a fine upper fabric having a homogeneous design can be used for bonding and bonding

stable and coarser üntergewebe be tethered. The upper fabric is executed in a binding, the

in terms of their sheet forming properties is comparable to a plain weave and thus optimally suited for the production of graphic paper. The lower fabric may be coarser in the longitudinal and transverse directions than that

Upper tissue and thus offer the following advantages: may have by the upper tissue in the tissue / sieve penetrated solids are not / hardly held in the lower tissue; the

Drainage of the sieve is exclusively by the Paper side or the upper fabric determines, ie, the lower fabric is open so formed that its influence on the

Is subordinate total flow. According to the invention, the coarse lower tissue can therefore be used to the sieve

to optimize mechanical stability, wear resistance and fabric thickness »

Thus, a very fine and homogeneous paper-side fabric layer is achieved (in particular, in comparison to the running side), whereas the running-side fabric layer can be made with higher openness and relatively thick longitudinal and transverse threads, which can contribute to a high mechanical strength. At the same time, a particularly stable connection of upper fabric layer and lower fabric layer is made possible;

generally by a weft or transverse thread-bound formation of the screen and in particular by a special design of the paper side / upper transverse threads with a binding zone. The upper transverse thread each have a course that corresponds in sections to a plain weave, wherein

Binding zones are created in which the respective upper

Cross thread under four consecutive upper longitudinal threads runs. These bonding zones can be used to tie the lower fabric layer to the upper fabric layer. As a result, a high binding frequency and thus a high stability of the sieve can be achieved. For example, settles with the

sieve according to the invention - compared to known sieves - achieve an increase in the binding frequency by up to 33%, using the same number of threads and the same computational fiber support index (Beran FSI).

Claims

1. paper machine screen, in particular sheet forming screen,

designed as a multi-layered fabric, in particular

two-ply fabric,

with an upper fabric layer and a lower fabric layer, the upper fabric layer having a plurality of upper layers

Longitudinal threads which run exclusively in the upper fabric layer, and a plurality of upper transverse threads, which are interwoven with the upper longitudinal threads and in each case extend at least predominantly in the upper fabric layer,

the lower fabric layer having a plurality of lower longitudinal threads extending exclusively in the lower fabric layer and a plurality of lower transverse threads interwoven with the lower longitudinal threads and

run exclusively in the lower fabric layer,

wherein the upper fabric layer has on its upper side a repeating upper weave repeat formed of nine upper longitudinal threads and three upper transverse threads,

the three upper transverse threads of the upper

Weave repeat in the upper weave repeat each on iron: under an upper longitudinal thread, over the next upper longitudinal thread, under the next upper longitudinal thread, over the next upper longitudinal thread, under the four next, successive upper longitudinal thread and over the subsequent upper longitudinal thread,

wherein in the upper binding repeat the course of the respective upper transverse thread with respect to the course of

adjacent upper transverse thread is arranged transversely offset by three upper longitudinal threads, and

wherein in the fabric at least some of the upper transverse threads are formed as connecting transverse threads for connecting the upper fabric layer with the lower fabric layer during its course under the four successive upper longitudinal threads temporarily change to the lower fabric layer and there undercut at least one lower longitudinal thread.

2. papermaking fabric according to claim 1,

wherein the lower longitudinal threads have a larger diameter than the upper longitudinal threads and / or

wherein the lower transverse threads have a larger diameter than the upper transverse threads.

3. A papermaking fabric according to claim 1 or 2,

the ratio of upper longitudinal threads to lower

Longitudinal threads in the entire fabric 3 to 2 or 1 to 1 and / or

the fabric being a repeating overall repeat in which the ratio of upper longitudinal threads to lower ones

Longitudinal threads 9 to 6 or 9 to 9, has or consists of such.

4. Papermaking fabric according to one of the preceding

Claims,

wherein the ratio of upper transverse threads to lower transverse threads in the entire fabric is 2 to 1 and / or

the fabric having a repeating overall repeat in which the ratio of upper transverse threads to lower

Transverse threads 6 to 3 or 12 to 6 is, has or consists of such

5. Papie masch inensieb after one of the preceding

Claims, wherein at least one of the three upper transverse threads of each upper weave repeat is formed as a connecting transverse thread, which temporarily changes during its course among the four successive upper longitudinal threads in the lower fabric layer and there undergoes at least one lower longitudinal thread under the upper fabric layer with the lower Fabric layer to connect.

6. The papermaking fabric of claim 5, wherein at least two, in particular each of the three upper transverse threads of each upper weave repeat is formed as a connecting transverse thread.

7. Papermaking fabric according to one of the preceding

Claims, wherein the respective connecting upper transverse thread for connecting the upper fabric layer with the lower fabric layer during its course under the four successive upper longitudinal threads undergoes exactly one lower longitudinal thread or exactly two consecutive lower longitudinal threads.

8. Papermaking fabric according to one of the preceding

Claims, wherein the combination of upper fabric layer and lower fabric layer exclusively through the upper

connecting cross threads takes place,

9. Papermaking fabric according to one of the preceding

Claims,

the upper fabric layer consists exclusively of one

Variety of adjacent upper binding reports exists and / or

wherein the respective upper binding repeat consists exclusively of the nine upper longitudinal threads and the three upper transverse threads.

10. Papermaking fabric according to one of the preceding

Claims,

wherein the lower transverse threads so with the lower

Longitudinal threads are interwoven that they form a dreischäftige or sechschäftige binding in the lower fabric layer, in which the course of the respective lower transverse thread repeats after three or six longitudinal threads, wherein the respective lower transverse thread in the

three-firm binding in particular initially over a lower longitudinal thread and then under the two subsequent lower longitudinal threads, and wherein the respective lower transverse thread in the six-bar binding in particular

first over a lower longitudinal thread and then under the five consecutive lower longitudinal threads.

11. Papermaking fabric according to one of the preceding

Claims, wherein the longitudinal threads as warp threads and the

Cross threads are formed as weft threads.