EP2004903B1 - Upper side, in particular paper side, for a paper machine forming fabric and paper machine forming fabric - Google Patents

Abstract

Multilayer web former wire comprises an upper layer in which longitudinal threads are interwoven with transverse threads to form periodic structures in the longitudinal (L) and transverse (T) directions, where the L structure comprises at least three threads, the T structure comprises at least nine threads, all L threads run alternately over three T threads and under three T threads and then under the remaining T threads, and pairs of adjacent L threads are longitudinally staggered relative to each other by at least three T threads. Multilayer web former wire comprises an upper (especially paper-side) layer in which longitudinal threads (21-24) are interwoven with transverse threads (1-12) to form periodic structures in the longitudinal (L) and transverse (T) directions, where the T structure comprises at least three times as many threads as the L structure, the L structure comprises at least three threads, the T structure comprises at least nine threads, all L threads run alternately over three T threads (1, 3, 5) and under three T threads (2, 4, 6) and then under the remaining T threads, and pairs of adjacent L threads are longitudinally staggered relative to each other by at least three T threads. An independent claim is also included for a paper machine wire with an upper layer as above.

Description

The invention relates to the construction of an upper side, in particular paper side for a multi-layered papermaking fabric and a pertinent papermaking fabric, in particular provided for the use of a wet end in a paper machine.

In the wet end of a paper machine, the formation of the paper sheet is carried out depending on the type of machine on one or between two paper machine screens. In this case, a suspension consisting of about 1% of fiber or excipients and 99% water is added uniformly to the papermaking screen and the solid constituents contained are separated from the water by a filtration process. Normally, the use of various dewatering elements until the end of the wet end achieves a solids content or dry content of 20 to 22%. The paper thus produced is already so strong that it can be transferred to the press section and dried further. In modern paper machines, such as gap shapers, the technology for carrying out this filtration process has been improved so much that at speeds of 2,000 m / min and more, significantly less than one second is needed.

While a number of paper technological parameters, such as whiteness, tensile strength and elongation mainly by the raw and Adjuvants are determined, the sheet forming screens have a significant influence on the basis weight and thickness profile, the fiber retention as well as the visible in the paper screen marking. Especially in the field of graphic papers, the quality requirements are high. The pertinent quality requirements are opposed by the fact that increasingly inferior raw materials such as waste paper are used and that one tries by lowering the weight per unit area to save raw materials and thus costs.

Already very early one has reacted to these trends in the development of the sheet forming screens for paper machines and implemented various approaches to a compromise between the highest possible fineness of the paper side, a robust and coarse machine side to achieve a long life and a total high stability of the mesh to reach.

To meet these requirements, the so-called two-ply mesh fabrics were developed, which are characterized by a longitudinal thread system with at least two transverse thread systems, wherein at least one transverse thread system is woven only on the paper side and the second exclusively on the machine side. Some embodiments of pertinent sheeting screens can be found, inter alia, in the following patent documents: EP 0 186 406 A3 . DE 31 43 433 A . DE 25 40 490 B2 . DE 22 63 476 B2 . DE 38 17 144 A1 . DE 38 01 051 A1 . DE 39 10 019 A1 as well as in the DE 41 07 633 C2 ,

Although this type of sheet forming screens is still widely used today, all these fabrics are characterized by a relatively low water permeability due to the closely juxtaposed MD yarns. Further, with this type of fabric, it is not possible to make the ideal paper side recognized as a plain weave and to join it to a lower fabric. Accordingly, it often happens that there are unwanted marks in the paper.

To overcome these disadvantages, efforts have been made to develop a screen in which the paper side consists of a plain weave. The pertinent three-ply composite fabrics consist of at least two separate layers of fabric, of which the upper is characterized by the plain weave and which is suitably connected to the other layers of fabric. To connect the layers together in the known solutions serve separate binding threads, which can form both longitudinal threads and transverse yarns. Furthermore, the pertinent compound has also been prepared by incorporating longitudinal and transverse thread systems of one fabric into the other fabric by transferring said threads from one layer of fabric to the next, and vice versa. Some examples of this can be found in the following documents: DE 33 18 985 A1 . DE 42 29 828 C2 . DE 29 17 694 C2 . EP 0 093 096 B1 . EP 0 069 101 B1 . EP 0 097 966 B1 and WO 93/00472 ,

With this type of known fabrics, the uniformity of the top could be improved so that the mark left in the paper significantly less precipitated than in the two-ply sieve and also the permeability was maintained at comparatively high number of threads on the paper side. This led to an increased use of three-ply screens in the aforementioned graphic papers.

Due to the multi-layer structure, however, the thickness of the paper machine wire increases considerably, as a result of which more water can be stored in the tissue and the drainage capacity is reduced to that extent. Another disadvantage of the three-ply composite fabrics relates to the ply compound. The individual layers of fabric connected to one another via binding threads are frequently subjected to bending during travel in the paper machine, whereby the one layer undergoes an extension relative to a neutral phase in the center of the screen, wherein at the same time the fabric layer opposite the neutral phase is compressed , It then comes regularly to a relaxation of the tissue connection, which can lead to the position shift in the advanced stage with occurring in extreme cases separation of the fabric layers, which leads to the becoming unusable of the papermaking fabric.

Although in the DE 100 30 650 C1 already described to counteract the ply separation, to use the machine direction yarns as binding threads, with the result that by changing the longitudinal yarn or machine direction yarns from the paper to the machine side and vice versa, there is a balance of stretching and compression of the two fabric sides; but even this type of binding can not compensate for the structural higher thickness of the composite fabric with its reduced drainage performance.

GB 2 391 557 A discloses a top consisting of a plurality of longitudinal threads interwoven with a plurality of transverse threads, with longitudinal and transverse repeats formed, the transverse thread repeat containing six times as many threads as the longitudinal thread repeat.

Based on this prior art, the present invention seeks to further improve the known solutions that a top or paper side of a papermaking fabric is formed, which realizes the advantages of a plain weave and yet a simple compact and robust structure for the tissue together the papermaker's fabric for which the fabric is used is reached. A passing-de Task solves a top, in particular paper side, with the features of claim 1 and a papermaking machine with the features of claim 5.

The solution according to the invention is characterized in that according to the feature configuration of claim 1, the top or paper side consists of a plurality of longitudinal threads, which are interwoven with a plurality of transverse threads and thereby rapports in the longitudinal and transverse directions, wherein the Querfadenrapport three times as many As with the longitudinal thread repeat and the longitudinal thread repeat, threads contain at least three threads and the transverse thread repeat is at least nine, all longitudinal threads alternatingly extending over three transverse threads and under three transverse threads and then under the remaining transverse threads of the transverse thread repeat, and two directly adjacent longitudinal threads extending longitudinally at least three transverse threads are shifted against each other. The stated object is also achieved by a papermaking machine with the features of claim 5.

The top according to the invention is designed to approximate the well-known plain weave and thus allows the production of mark-free paper. Nevertheless, a high drainage can be achieved by the special design of the top and, if one provides the top with correspondingly suitable further layers of fabric on the bottom, a compact and robust construction is achieved, which counteracts the unwanted layer separation. The claimed top or paper side can be obtained inexpensively on conventional weaving devices, so that it is possible to dispense with special cost-intensive machine devices. The use of at least three machine direction yarns involves the incorporation of additional machine side cross direction yarns possible and thus achieved in terms of an ideal plain weave high uniformity for the top or top fabric layer of a papermaking fabric.

The claimed binding principle can be extended to almost any number of longitudinal threads in the repeat and is readily feasible for three, five and six longitudinal threads within a repeat. The more longitudinal threads are present in the repeat, the more shifts the length ratio of longitudinal thread to cross-direction yarn on the upper side in the direction of cross-direction yarn. In that regard, the binding is getting wider, which is fundamentally detrimental to the uniformity of the paper side, but it causes an ever better support for the paper fibers emerging mainly longitudinally from the headbox of the paper machine. Depending on the requirements occurring in practice, the upper side can be adapted to the circumstances in this simple way.

In a particularly advantageous embodiment of the solution according to the invention, the upper side of a heat-setting is supplied, resulting in a longitudinal stretching and a transformation of the fabric structure, in which the course of the longitudinal threads in the area in which they bind with the upper transverse threads, no longer strictly vertical or in the longitudinal direction, but is slightly diagonally oriented.

The integration of the machine-side transverse threads, ie the lower fabric with the upper fabric or the upper side can be done in many ways. In a preferred embodiment, the ratio of three upper transverse threads to two lower transverse threads is selected. The slope of the lower fabric is preferably two.

Basically, however, other cross thread ratios are conceivable here.

Further advantageous embodiments of the solution according to the invention are the subject of the other dependent claims.

Fig. 1

ein erstes Ausführungsbeispiel betreffend eine Gewebeoberfläche mit einem Längsfadenrapport von vier Fäden und einem Querfa- denrapport von zwölf Fäden entsprechend der Darstellung einer Bindungspatrone nach Fig. 4b);

Fig. 2

ein zweites Ausführungsbeispiel betreffend eine Gewebeoberfläche mit einem Längsfadenrapport von drei Fäden und einem Querfa- denrapport von neun Fäden entsprechend der Darstellung einer Bindungspatrone nach Fig. 4a);

Fig. 3

ein drittes Ausführungsbeispiel betreffend eine Gewebeoberfläche mit einem Längsfadenrapport von fünf Fäden und einem Querfa- denrapport von 15 Fäden entsprechend der Darstellung einer Bin- dungspatrone nach Fig. 4c);

Fig. 4

verschiedene Ausführungsbeispiele an Bindungspatronen, wobei

Fig. 4a)

einem Längsfadenrapport von drei und einem Querfaden- rapport von neun Fäden,

Fig. 4b)

einem Längsfadenrapport von vier und einem Querfaden- rapport von zwölf Fäden,

Fig. 4c)

einem Längsfadenrapport von fünf und einem Querfaden- rapport von 15 Fäden,

Fig. 4d)

einem Längsfadenrapport von sechs und einem Querfa- denrapport von 18 Fäden entspricht;

Fig. 5

Längsfadenverläufe eines Ausführungsbeispieles einer Oberfläche mit einem Längsfadenrapport von vier und einem Querfadenrap- port von zwölf Fäden und eingewebten maschinenseitigen Schüs- sen;

Fig. 6

eine an sich bekannte Leinwandbindung;

Fig. 7

eine Darstellung der Oberseite mit einem Längsfadenrapport von vier und einem Querfadenrapport von zwölf Fäden im schemati- schen Aufbau.

In the following, the solution according to the invention will be explained in more detail with reference to various embodiments according to the drawing. This show in a schematic representation of the

Fig. 1

a first embodiment relating to a fabric surface with a longitudinal thread repeat of four threads and a Querfa- denrapport of twelve threads according to the representation of a binding cartridge according to Fig. 4b );

Fig. 2

a second embodiment relating to a fabric surface with a longitudinal thread repeat of three threads and a Querfa- repeating nine threads according to the representation of a binding cartridge according to Fig. 4a );

Fig. 3

A third exemplary embodiment relating to a fabric surface with a longitudinal thread repeat of five threads and a transverse thread repeat of 15 threads according to the illustration of a binding cartridge according to FIG Fig. 4c );

Fig. 4

various embodiments of binding cartridges, wherein

Fig. 4a)

a longitudinal thread repeat of three and a cross thread repeat of nine threads,

Fig. 4b)

a longitudinal thread repeat of four and a cross thread repeat of twelve threads,

Fig. 4c)

a longitudinal thread repeat of five and a cross thread repeat of 15 threads,

Fig. 4d)

corresponds to a longitudinal thread repeat of six and a transverse thread repeat of eighteen threads;

Fig. 5

Longitudinal thread courses of an embodiment of a surface with a longitudinal thread repeat of four and a Querfadenrap- port of twelve threads and woven machine-side shots;

Fig. 6

a known plain weave;

Fig. 7

a representation of the top with a longitudinal thread repeat of four and a transverse thread repeat of twelve threads in the schematic structure.

The subject matter of the invention relates to a multi-ply papermachine fabric having a paper side which, in an approximation of the well-known plain weave (cf. Fig. 6 ), but by the use of a plurality of machine direction yarns to allow the integration of additional machine-side cross direction yarns.

Looking more closely at the ideal known plain weave, as in Fig. 6 is shown, then the high uniformity of this bond is mainly due to the short rapport 101 of only two longitudinal threads and transverse yarns. If, in addition, the same number of threads and thread diameters are used in the longitudinal direction and in the transverse direction, a square stitch and a uniform height of transverse thread and longitudinal thread offset are obtained.

• mindestens drei Maschinenrichtungsfäden einzusetzen,
• deren Abstand zueinander kleiner als 20 % des Durchmessers eines Längsfadens ist, und
• den Querfadenrapport dreimal so lang auszubilden wie den Längsfadenrapport, wobei
• jeder Maschinenrichtungsfaden alternierend über drei und unter drei Querrichtungsfäden und anschließend unter der Oberseite zu verlaufen hat und
• die Bindung eine Steigung drei besitzt.

Under the condition thread count = 2 / thread diameter, the distance 102 and 105 between the adjacent stitches is equal to the stitch width 106 and the stitch length 103. In order to come as close as possible to a pertinent canvas-like top, the solution according to the invention provides, inter alia,

• use at least three machine direction threads,
• the distance between them is less than 20% of the diameter of a longitudinal thread, and
• the Querfadenrapport three times as long form as the longitudinal thread repeat, wherein
• each machine direction yarn has to run alternately over three and under three transverse yarns and then below the top, and
• the bond has a slope of three.

The Fig. 4 shows the pertinent bonding principle based on four different longitudinal thread reports. In this illustration, as is customary in textile technology, the machine direction threads are represented by columns and the cross direction threads by lines. Furthermore, crossing points at which the respective longitudinal thread runs over an assignable transverse thread are marked by a cross.

In the Fig. 4a ), the solution according to the invention is applied to a longitudinal thread repeat of three threads 21 to 23. The Querfadenrapport has a length of nine threads 1 to 9, wherein the first longitudinal thread 21 alternately binds with the shots 1 to 6, with respect to the shots 1, 3 and 5 and below with respect to the shots 2, 4 and 6. Thereafter, the longitudinal thread remains below the shots 7 to 9.

The directly to the right of adjacent longitudinal thread 22 has the same course; but moved up by three transverse threads. The above missing shots are added below the starting point. This shift is commonly referred to by the term "slope". The longitudinal thread 22 thus begins at the transverse thread 4 and then runs like the longitudinal thread 21st

Fig. 4b ) shows a preferred embodiment of the solution according to the invention with a longitudinal thread repeat of four threads 21 to 24. The Querfadenrapport thus results in twelve threads 1 to 12 and thus to a length which is three times as long as the longitudinal thread repeat. Again, the first six shots 1 to 6 by the longitudinal thread 21 alternately about 1, 3 and 5 and including 2, 4 and 6 are involved. The remaining shots 7 to 12 remain below the longitudinal thread 21. Comparable arrangements result for the further longitudinal threads 22, 23 and 24.

The schematically woven surface corresponding to the binding cartridge after the Fig. 4b ) is in Fig. 7 , For the same diameters of longitudinal and transverse threads 102 and 105 and the same transverse thread pitches 103, the floating lengths of the longitudinal and transverse threads 104 and 107 can be displayed the same. Only the mesh width 106 is different.

If a customary heat-setting method is used for the plastic threads used, the longitudinal stretching during the heat-setting results in a transformation of the structure which is found in FIG Fig. 1 can be seen schematically.

The course of the longitudinal threads 21 to 24 "'is no longer strictly vertical or in the region in which they bind with the upper transverse threads 1 to 5 Aligned longitudinally, but is slightly diagonally oriented. Along the longitudinal thread 21, z. In Fig. 1 considered, this means that the Ketthochgang on the transverse thread 1 is further to the right than that on the transverse thread 3 and the longitudinal thread runway above the transverse thread 5 is the leftmost. This is achieved in that the relatively straight woven transverse threads are bent in the image plane when stretching the longitudinal threads and thereby reorient the longitudinal threads. Thus, from the one large mesh 118, two smaller ones 119 and 120 ( Fig. 1 ), which come very close to the stitches in the plain weave.

This binding principle can be extended to almost any number of longitudinal threads in the repeat, which in the FIGS. 4a), 4c) and 4d ) is shown by way of example for three, five and six longitudinal threads. The more longitudinal threads are present in the repeat, the more shifts the length ratio of longitudinal thread to cross-direction yarn on the top in the direction of cross-direction thread. This leads to a corresponding widening, which is undesirable in relation to the uniformity of the paper side, but causes an increasingly better support for the paper fibers emerging mainly longitudinally from the paper spout of the paper machine. Depending on the considerations of expediency, the upper side can then be easily adapted to the circumstances. The first embodiment of the Fig. 1 As far as the surface of the solution according to the invention with a longitudinal thread repeat of four threads 21 to 24 and a transverse thread repeat of twelve threads 1 to 12 corresponding to the binding cartridge according to the invention Fig. 4b ). Corresponding repetitive repeats or thread arrangements are indicated with a raised line behind the respective reference character.

In the first embodiment, the first longitudinal thread 21 binds alternately with the first six transverse threads 1 to 6 above and below and then extends only below the remaining transverse threads 7 to 12. The next longitudinal threads 22, 23 and 24 rise within the repeat by three transverse threads, in this case right above. As with any binding, a slope to the left is possible in principle, which would then result in a mirrored image of the surface (not shown).

In the embodiments of the Figures 2 and 3 an embodiment with a longitudinal thread repeat of three or five threads is shown. Again, a total of four longitudinal thread reports are shown side by side to convey a better impression of the surface can.

In the fourth embodiment of the Fig. 5 there is shown the use of the surface according to the invention in a double-layered sheet forming wire as a papermaking wire, wherein the longitudinal threads are shown cut in their course and the transverse threads. In this way, it is shown how the region of the longitudinal threads, which runs below the upper transverse threads, can be used to incorporate lower transverse threads. This refers to the area that is located at the longitudinal thread 21 below the transverse threads 6 to 12 or 6 'to 12'.

The surface used here corresponds to the one in Fig. 1 shown with a longitudinal thread repeat of four threads and, accordingly, a Querfadenrapport of twelve threads. The transverse thread number was chosen in the ratio of three upper transverse threads to two lower transverse threads. At the given slope of the upper fabric of three, the slope for the lower fabric is two. Thus, both the ratios of the transverse thread numbers and the pitch between the upper and lower fabric are the same, which has a favorable effect on the overall construction. With the embodiment of the Fig. 5 is the Fleet length of the lower transverse threads twice as long designed as the longitudinal thread repeat of the upper fabric, so a total of eight threads included. The surface of the invention can thus be used as a paper page for a variety of different machine pages and thus sub-fabrics.

Claims (9)

1. An upper side, in particular a paper side, for a multilayer sheet forming sieve, in particular intended for use in a wet end of a paper machine, which consists of a plurality of longitudinal threads (21, 22, 23, ... ) which are woven with a plurality of transverse threads (1, 2, 3 ... ) and thereby form repeats in the longitudinal direction and transverse direction, the transverse thread repeat containing three times as many threads as the longitudinal thread repeat, and the longitudinal thread repeat consisting at least of three longitudinal threads (21, 22, 23) and the transverse thread repeat accordingly at least of nine transverse threads (1, 2, 3, ... , 9), all longitudinal threads running in alternation over three transverse threads (1, 3, 5) and under three transverse threads (2, 4, 6) and then under the remaining transverse threads (7, 8, 9, ... ) of the transverse thread repeat, and two directly adjacent longitudinal threads (21 and 22, 22 and 23, 23 and 24, ... ) being shifted against one another in the longitudinal direction by at least three transverse threads.
2. The upper side according to claim 1, characterized in that the longitudinal thread repeat consists of four, five or six longitudinal threads and the transverse thread repeat in a corresponding assignment consists of twelve, fifteen or eighteen transverse threads.
3. The upper side according to claim 1 or 2, characterized in that the distance of the respective transverse threads (1, 2, 3, ... ) of one transverse thread repeat to one another is less than 20% of the diameter of a longitudinal thread (21).
4. The upper side according to any of claims 1 to 3, characterized in that after a longitudinal extension in heat setting the thread progression is reoriented such that the longitudinal threads (21 to 24"') run diagonally in the regions in which they bind with the upper transverse threads (1 to 5).
5. A paper machine sieve, characterized in that it has an upper side according to any of claims 1 to 4.
6. The paper machine sieve according to claim 5, characterized in that it is formed in two layers, with an upper fabric formed by the upper side and a lower fabric, with a selected ratio of three upper transverse threads (1 to 12, 1' to 12') of the upper fabric to two lower transverse threads (51 to 58, 59 to 66) of the lower fabric.
7. The paper machine sieve according to claim 6, characterized in that the pitch, that is, the shifting in the longitudinal direction between two directly adjacent longitudinal threads by a number of transverse threads, is two in the lower fabric and three in the upper fabric.
8. The paper machine sieve according to claim 6 or claim 7, characterized in that the length of a float formed by the longitudinal threads and running over the lower transverse threads (51 to 66) is formed with twice the length of the longitudinal thread repeat of the upper fabric.
9. The paper machine sieve according to claim 8, characterized in that the transverse thread repeat of the lower fabric is dimensioned with such a length so that a float is achieved which is formed by the longitudinal threads and runs over eight lower transverse threads (51 to 66).

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