FI70947B - FORMERINGSVIRA - Google Patents

Description

ANNOUNCEMENT Π Γ) Q Λ 1 Β 11 UTLÄGGNINGSSKRIFT 7094 7 KäS (45) ^ ^ ^ (51) Kv.lk. * / Lnt.CI.4 D 21 F 1/10 FINLAND (21) Patenttlhakemui - Patentansökning 791460 (22) Application threshold - Ansökningsdag 07 · 05.79 (F *) (23) Start date - Giltighetsdag 07 · 05 -79 (41) Has become public - Blivlt offentlig 13.12.79

National Board of Patents and Registration Date of publication and publication—

Patent-OCh registerstyrelsen '' Ansökan utlagd och utl.skrlften publlcerad 18.07.B6 (86) Kv. application - Int. ansökan (32) (33) (31) Privilege claimed - Begärd priority 12.06.78 Sweden-Sverige (SE) 7806764-2 (71) Nordiskafilt AB, Gamletullsgatan 3 »302 44 Halmstad, Sweden-Sverige (SE) (72) Arne Boris Johansson, Halmstad, Francisco Lorente Codorniu, Äled,

Sweden i-Sver ige (SE) (74) Leitzinger Oy (54) Muotoi1 uviira - Formeringsvira

When making paper in paper machines, the fibrous slurry flows onto the reticulated wire. Water is allowed to drain from the pulp through the openings in the wire. On top of the wire, the fibers are formed into a sheet. Since water leakage occurs where those wire material of the wire does not prevent it, it is most important that these flow-through locations are evenly distributed on the surface of the wire. The permeability of the shaping wire must be a certain amount at the same time as the surface of the wire must be very fine-grained due to wire marks and fiber loss. However, the fine-mesh wire, which consists of thin yarns, is less wear-resistant and stable, and its service life has thus been very limited. Until the early 1960s, only single-layer metal wires were used in sheeting. In certain areas, metal wires were replaced by more durable but less stable man-made fiber wires, the so-called plastic wire. Due to its low stability, single-layer plastic fabrics could not be used in large and high-speed machines. Only. the so-called. with the advent of double-layer design fabrics, more artificial material was used in these large and high-speed machines. The forming wire was subjected to considerable tensile stress in such machines, which it had to withstand without stretching in the longitudinal direction and without shrinking in the transverse direction to such an extent that it could no longer be used for its intended purpose.

The so-called the two-layer forming wires consist of two layers of synthetic weft yarns joining the layers together with synthetic warp yarns. These wires meet to some extent the requirement of a fine-mesh shaping surface, which surface consists of fine yarns and a tread where the yarns are coarser and more wear-resistant. This can be done by using different yarn dimensions and / or fibrous material in both weft layers. However, this counter-requirement is not met by a layer of yarn occurring in the other direction alone. i.e. a layer of warp yarn connecting the layers. From a design point of view, these warp yarns should be as fine as possible, but as machine parallel yarns, they should be able to receive the tensile stresses encountered without stretching an unusual amount.

It is the wish of every person skilled in the art to provide a forming wire consisting of two layers of complete wires, each of which would have warp and weft yarns joined together.

The wire portion closest to the material to be formed is regularly composed of fine yarns made into a fine-mesh shape, while the bottom part is formed of coarser and more wear-resistant yarns made into a coarser-mesh shape.

The fact that this wish could not be applied in practice is due to the difficulty of joining the two wire sections together without disturbing the fine-mesh wire section to such an extent that it appeared on the sheet of paper as a wire mark.

U.S. Pat. No. 3,127,308 discloses a design wire consisting of a fine-grained side mainly of paper web and a coarse-grained polish acting as a wear side. Both of these sides are made up of complete fabrics woven together. The patent discloses a connecting bond according to which a coarse warp yarn 61a connects both wire parts 61 and 62.

Also in the past, the joining of complete tissues with special warp yarns has been proposed.

Thus, in the structures hitherto known, both fabrics have been combined either with a warp yarn belonging to both fabrics or with different 70947 dull binder warp yarns. In wire-like fabrics, it is normal for the weft yarns to be completely straight in the fabrics after weaving, while the warp yarns are wavy, forming the surface of the wire itself. Of course, the actual waveform can be changed by stretching, followed by thermal bonding so that the wave formation of the warp yarns is reduced while the weft yarns acquire some waveform. However, such a procedure can do little to smooth out the irregularities that arise when warp yarns are woven. If the fine warp yarn of the Imainen wire section is used as a connecting yarn, an unevenness will be created on the delicate paper side of the wire, because this warp yarn must be connected to the bottom of Riga at regular intervals. If a coarse yarn of a coarse-mesh wire portion or a separate warp yarn is used as the connecting yarn, inaccuracy of the paper side of the wire will occur when this yarn is joined to the fine-mesh wire portion on the paper web side. These irregularities, which result from joining using warp yarns, are sufficient to cause marks on more sensitive grades of paper, such as magazine paper.

Joining with warp yarns is also considerably more complicated from a manufacturing point of view, because the binding yarns are of a different size than other warp yarns, e.g. from their geometric design. Binding yarns must therefore be created with special weaving machine supports and run at a different speed than other warp yarns.

The present invention relates to a forming wire for paper, cellulose or similar machines, the wire comprising a first warp yarn layer and a first weft yarn layer woven together into a complete fabric, a second warp yarn layer and a second weft yarn layer woven together into a second complete fabric. Significant to the invention is that said first and second fabrics are joined together by special connective weft yarns interposed between the fabrics, which are connected to the yarns of said first and second warp yarn layers.

The above-mentioned situation that the weft yarns are completely straight inside the fabric after weaving causes the connective weft yarns to be in the same position, and the wavy warp yarns on both sides of the wire meander around these binder yarns. The binding points themselves are thus located inside the tissue body and not, as in 4,70947 warp-bonded structures, on its surface. The surfaces of the wire, and especially then the surface facing the web of material to be formed, are not affected by the bonding points. It has also been found that if the surface of the wire against the web of material is already tangled in the raw fabric and undisturbed from the bonding points, a smoother surface is formed even when the wire is subjected to tension during thermal bonding. The function of the binding yarns in the wire is only to connect the surface and base fabric to each other. Their dimensioning and material may therefore be different from other yarn material. Preferably, a finer and softer yarn material is used as the binding yarn.

The shaping wire according to the invention is, in the usual way, woven endless mash or seamed as such. In an endless woven structure, the machine direction yarns are formed from the weft yarns of the fabric while the warp yarns form a cross-yarn system in the wire operating position. In an endlessly seamed structure, the situation is the opposite.

The invention will now be explained in more detail with reference to the accompanying schematic sectional drawing showing various weaving patterns along warp yarns, in which:

Figures 1-3 show embodiments of a relatively fine-meshed fabric 1 in the position of use of the wire on the side of the material to be shaped. This fabric - hereinafter referred to as the cover fabric - is made in two arms, which means that each warp yarn 2 binds every other weft yarn 3a from above and every other weft yarn 3b from below. The second and coarser mesh fabric 4, woven into a four-arm Kypert shape, forms the base fabric of the wire. This base fabric 4 also has two complete yarn systems, namely a warp yarn 5 running over three successive weft yarns 6a and one, fourth weft yarn 6b. Weft yarns 7 are woven between these two fabrics 1, 4, which are connected to the warp yarns 2, 5 of both the cover and the base fabric. These connective weft yarns 7 can be placed sparsely or denser.

70947

In Figure 1, the connective weft yarns are relatively sparse, namely only after every twelfth weft yarn of the cover fabric.

Fig. 2 shows by way of example a somewhat denser arrangement of the connective weft yarns 7, and

Figure 3 further shows an even denser arrangement of the connective tissue yarns 7.

Figures 4 and 5 show how the shaping of the cover fabric 1 and the base fabric 4 can be performed in a number of ways. In Figure 4, both fabrics 1 and 4 are in four-arm shape. The embodiment according to Figure 5 differs from the previous one in that both fabrics 1, 4 are woven in a three-arm shape and that the density ratio of the weft yarns in the cover and base fabrics is 3: 1 instead of 2: 1, as shown in the figure.

9 The fabric design and the density ratio 1,4 of the cover and base fabric 1, 4 can thus be varied in different ways, as can the different density ratios between the fabrics. What they all have in common is that both fabrics are anchored into one system with connective weft yarns 7 woven between the fabrics 1, 4. Since these weft yarns 7, like the other weft yarns 3a, 3b, 6a, 6b, are relatively straight while the warp yarns 2, 5 are corrugated, the weft yarns 7 will be placed entirely inside the double wire after weaving. Thus, these connective weft yarns 7 do not come into contact with the surface portions of the wire and thus, as is the case with binder warp yarns, cannot interfere with the regularity of the total fabric between the two yarn systems 2 and 3a, 3b of the cover fabric.