FI83243B - FORMERINGSVIRA. - Google Patents

Description

1 83243

A forming. - Formering lever.

The invention relates to a forming wire for paper, cellulose or similar machines, comprising a first fabric which, in the position of use, is turned against the material to be formed, and a second fabric bonded to the first fabric.

In conventional paper machine manufacturing, the fibrous sludge in the water is allowed to flow onto a wire-like wire. The water in the pulp exits through the openings in the wire. The fibers are then formed into a sheet on the upper side of the wire.

Conventional paper design in a flat wire machine is now increasingly being replaced by double wire design, where a pulp jet is directed directly at a converging nip between two wires running at the same speed. The pulp is compressed between the wires, squeezing the water out of the pulp.

In both cases, the fibrous slurry usually contains more than 99% water, most of which should be removed by allowing the water to flow through the wire. The flow of water takes place in those parts of the wire where the wire material of the wire does not impede this.

It is important that these flow-through points are very small, i.e., the wire must be very fine-grained to avoid fiber loss. At the same time, the permeability of the shaping wire must be of a certain magnitude to allow large volumes of water to flow through. Thus, several small flow-through points must be formed on the surface of the wire, mainly the fibrous web, with the result that the material of the surface of the wire must be formed of thin yarns. However, the fine mesh wire becomes less abrasion resistant and less stable and therefore has a very limited service life. Due to their low stability, single ply man-made fiber fabrics could not be used in large and high speed 2 83243 flat wire paper machines. The shaping wire in such machines is subjected to considerable tensile stress, which it must receive without the longitudinal elongation and the transverse shrinkage reaching such values that the wire can no longer be used for its intended purpose.

Synthetic fiber material gained greater use in these large and fast paper machines for the first time only when the so-called two-layer design wires came into use. These wires consist of two layers of synthetic weft yarns as well as synthetic warp yarns connecting the layers. In these wires, these opposing requirements of a fine mesh forming wire formed of fine yarns and a tread where the yarns are coarser and more wear resistant can be met to some extent by using different yarn dimensions and / or fibrous material in both weft yarn layers. However, these opposing requirements are not able to be met by the warp yarns connecting the layers. From a design point of view, these yarns should be as fine as possible, but as machine-direction yarns, they should be able to absorb the tensile stresses that occur without their elongation becoming abnormally high.

The next step in development was the bonding of the two monolayer tissues to each other, as disclosed in 5E-PS 7806764-2. The object of the present invention was to provide interference without interference on the paper side. This was perfectly accomplished, and this type of styling fabric is now used to design fine grades of paper where synthetic styling fabrics have hitherto been unusable. However, the difficulty in arranging the elongation / load properties between the two fabrics has resulted in one of these fabrics receiving most of the load and the properties being slightly degraded compared to the double wire. In addition, the strength of the wire stitch has not been satisfactory.

3 83243

The present invention is characterized in that the second fabric is formed of a first and a second yarn system parallel to each other and substantially in superimposed planes, and a third yarn system perpendicular to said two systems and which binds the two systems together.

Preferably, both parallel systems of the second fabric are formed of weft yarns, while the third system is formed of warp yarns.

Preferably, the yarns of the first fabric have a smaller diameter than the yarns of the second fabric.

The shaping wire according to the invention can be formed from a first fabric, the structure of which is so fine-meshed that it allows a very even flow of water without fiber loss and the tendency for wire marks. At the same time, improved stability is achieved solely by the second tissue. In this case, the first tissue does not need to be designed to receive the load. Stitch strength that has been unsatisfactory. in previous design fabrics that have had double fabrics, there has been a significant improvement.

The wire can still be more targeted _ ·; equip with a loop in another fabric. The dimension of the loops can be chosen to be smaller than the thickness of the second fabric and thus protected from wear.

Of the two parallel wire systems in the second fabric, which is closest to the dewatering element of the machine, it can be formed as a whole from a very wear-resistant ··; material.

'83243

In double wire machines, the advantage is the ability of the wire to hold water.

Another advantage is the rigidity of the wire, which causes the wire to run more evenly without any tendency to form ridges.

In the following, the invention will be described with reference to the accompanying schematic drawings, in which Figures 1 to 4 show sections along another yarn direction, the most suitable warp yarn direction, in some different binding patterns.

The shaping wire according to the invention is preferably woven flat and joined endlessly. In this case, the warp yarns form the machine direction yarns of the wire, while the weft yarns form the yarns transverse to the wire in the operating position. Alternatively, the wire may also be woven endless, with the ratio of yarns to machine direction being the opposite.

The embodiments according to Figures 1-4 have a first fabric 1, which is more preferably fine-meshed and which, in the position of use of the wire, is turned against the material to be formed. This fabric - hereinafter referred to as the main fabric - is shown in Figures 1, 2 and 4 in the double-arm pattern, which includes each yarn 2 in one direction, e.g. warp yarn, tying every other yarn 3a above and every other yarn 3b in another direction, e.g. weft yarn direction. Other fabric models can also be used for the main fabric, for example the Batavia model shown in Figure 3.

The second fabric 4 is placed under the main fabric and forms the base fabric of the wire, which is against the dewatering element.

This second fabric 4 is more preferably coarser-eyed and consists of a two-yarn system 5, 6 in the other direction, for example in the weft yarn direction, which yarn systems are parallel to each other and located on the overlaps. The additional yarn system 7 is in a second direction, for example in the warp yarn direction, perpendicular to the double yarn system 5, 6. The yarns 7 can bind the yarns 5, 6 together in a selected pattern, for example in the eight-arm pattern shown in Figures 1, 3 or in the four-arm pattern shown in Figure 4. Both yarn systems 5 and 6 may have a different number of yarns. For example, the yarn system 3 may have twice the number of yarns compared to the yarn system 6 illustrated in Figure 2.

Both tissues are bound together (not shown). Most preferably, special connective weft yarns are used, which bind together the warp yarns from both fabrics. It is also possible to use binder warp yarns. Some yarns belonging to a yarn system of another fabric may also be joined by perpendicular yarns of another fabric.

The forming wire according to the invention can be formed of a fine-mesh overlay fabric with 0.17 mm polyester monofilament 2, 3 30 yarns / cm in both directions. The base fabric interlocking yarn system 7 may be 0.25 mm polyester monofilament with a yarn density of 30 yarns / cm. From the double parallel yarn system 5, 6 in the base fabric, the yarns 5 closest to the main fabric can be formed of 0.22 mm polyester monofilament at a yarn density of 13 yarns / cm. The lower 6 of the two parallel yarn systems preferably consists entirely or partially of a wear-resistant monofilament material, for example ... polyamide, which, however, does not preclude the use of other materials. The yarn dimension of the yarn in the system 6 is preferably · 0.30 mm and the yarn density is 15 yarns / cm or 7.5 yarns / cm if a pattern according to Fig. 2 or similar is used.

The invention is not limited to the embodiments described and exemplified, but may take many other forms within the scope of the claims.

Claims (6)

6 83243 A forming wire for paper, cellulose or similar machines, comprising a first fabric having first and second systems of perpendicularly opposed yarns, the first fabric in the position of use turned against the material to be formed, and a second fabric bonded to the first fabric, characterized in that that the second fabric is formed by a first and a second yarn system (5, 6) parallel to each other and substantially in superimposed planes, and a third yarn system (7) perpendicular to said two systems (5, 6) and which binds the two together; systems (5, 6). Forming wire according to Claim 1, characterized in that the two parallel systems (5, 6) of the second fabric (4) are formed from weft yarns, while the third system (7) is formed from warp yarns. Forming wire according to Claim 1, characterized in that the yarns (2, 3) of the first fabric (1) have a smaller diameter than the yarns (5, 6, 7) of the second fabric (4). Styling fabric according to one of the preceding claims, characterized in that the two fabrics (1, 4) are connected to one another by means of special connective weft yarns. Forming wire according to one of Claims 1 to 3, characterized in that the two fabrics (1, 4) are connected to one another by means of special binding warp yarns. 7 83243 Forming wire according to one of Claims 1 to 3, characterized in that the two fabrics (1, 4) are connected to one another in such a way that some of the elements comprising the yarn system of the second fabric are bonded to the second fabric by perpendicular yarns. 8 83243