FI57623C - AVVATTNINGSFILT AVSEDD ATT ANVAENDAS I PAPPERSMASKIN - Google Patents

Description

R5F ^ I Γβ] (11) ANNOUNCEMENT - MTa l J 1} UTLÄGGNINGSSKRIFT 0 762 3

Patent r.cdielat

Ns "^ (51) Kv.ik? /Into.3 D 05 D 1/00 // D 21 P 1/10

FINLAND —FINLAND ffl) P »t» nttlh «k« mu »-HfnttnAWnt 582 / 7U

(22) Hakamltpilvl - Anattknlnftdtf 27.02.7t

(23) AikupUvi — GIMgh «tadt | 27.02.7U

(41) Tullut | ulktMkst - Bllvit offmtllg

Manttl ·) · raklMarilwIlKM - N— * k—

Pttant · oeh r * gi> t «rttyr« lMn '' AinMcm uttagd oeh utl.ikrift «n puMkwrad 30 .. 80 (32) (33) (31) *** <··« * ttuoHwiii — a * g * rd priority i8.oU.73 USA (US) 352320 (71) Albany International Corp., Appleton, Wisconsin, USA (US) (72) Cleon J. Egan, Kaukauna, Wisconsin, USA (US) (7U) Oy Kolster Ab The present invention relates to a drying fabric made of interwoven machine direction yarns and yarns transverse to these machines, the yarns being woven into a four-line weaving pattern, the yarns being woven into a four-line weaving pattern, fully synthetic material or metal or metal-coated wires.

In flatbed papermaking, the pulp deposit comes on a wide conveyor belt woven from a mesh fabric. Water is absorbed from the pulp through the fabric, whereby the paper fibers in the pulp form a paper web, i.e. its initial stage. The web then moves from the flat wire machine to the drying section of the paper machine.

The fabrics used in flat wire machines are made in a wide variety of weaving patterns. The range of materials is also wide. For several years, the the fabrics were woven from metal wire. Soft brass yarn was used as the weft yarn "inside" the fabric and bronze yarn as the warp yarn. Smooth weaving, so-called semi-twill weaving and several four-thread patterns have been used as weaving patterns, and synthetic yarns, sometimes in combination with metal wire, have also been used in recent years, and metal wire coated with synthetic material has also been tried to some extent.

There is a rich selection of synthetic yarns. In the past, some nylon was used for the fabrics of flat wire machines because it can withstand heavy wear, but later it was switched to polyester yarns, which are practically "waterproof" and which the pulp is generally unable to wear. Synthetic yarns have also been both single and multi-stranded. However, it has been a difficulty for them not to stabilize 1. settle like a metal wire when they have to bend when weaving the fabric. For this reason, several methods have been developed for stabilizing the drying fabrics woven from synthetic yarns in size after the weaving step.

Many requirements are placed on the drying fabric of a flat wire machine. 1. The upper side of the paper web forming surface is independently of the network structure of the fabric must be flat, since the paper web may not be marked material. In addition, the fabric must be able to dry the paper web in the correct proportions, i.e. its water permeability must be suitable for the purpose in question. The fabric must also be able to prevent fine pulp fibers from being washed out of the pulp with the water leaving the fabric. The fabric must therefore act as a paper web forming device in which the paper fibers are joined together in a suitable ratio in the transverse direction of the machine. Underside of the fabric 1. its actual tread must not make grooves in the suction boxes, rollers or other surfaces of the machine. The tensile strength of the fabric must also be high enough because the fabric has to move on the rollers at high speed. In addition, the fabric must be unchanged in size, ie it must not stretch too much. The fabric must also remain smooth. So it must not bend at any point or in waves. The fabric must also be woven in such a way that it can be joined into a single belt with sufficiently strong seams and long-lasting seams.

. It is an object of the invention to provide a fabric which lasts a long time in use, since the downtime of the machine due to the installation and removal of the fabric of the flat wire machine becomes very expensive. Some metal fabrics have only lasted a few days on a paper machine, while fabrics made from synthetic materials have had a lifespan of weeks, even months.

3 57623 As a result, the paper industry has moved from metal fabric to synthetic materials. As it has been possible to increase the wear resistance of the fabric, it naturally wears less when it comes into contact with the rollers and other parts of the machine's suction boxes. In addition, the non-corrosivity of synthetic materials in the handling of chemical substances has increased their use.

In addition to the the fabric must meet the numerous requirements outlined above, each fabric used in a paper machine must be made "tailor-made" to fit the particular machine in question. For this reason, weaving structures, patterns, and materials that have proven good on one machine may no longer provide satisfactory results on another paper machine. The mesh structure of the fabric must also be taken into account. Some fabrics are woven so "coarse" that they do not even have ten warp yarns per inch, while some fabrics may have as many as several hundred warp yarns per inch. There are usually fewer weft yarns per inch. However, there are also significant exceptions to this general principle. All warp yarns are usually the same thickness, as are all weft yarns. However, the relative thickness of the weft and warp yarns may vary. If, instead, two yarns of different thicknesses are used as the weft yarn, the tread of the fabric becomes more uneven than with conventional weaving. Now, it may be a little wrong to talk about the surface of the fabric, because in this case it is an open mesh made up of yarns woven into knees at the binding points, resulting in a wavy pattern that does not actually delimit a certain plane. Nevertheless, the word surface is used in this specification to mean the general outlines of the fabric when viewed from either side thereof, and the bonding points of the yarn are said to be at certain levels. This again means that po. the points are at a certain plane or at a certain height in relation to the maximum thickness of the fabric, measured from the outer knee surfaces of the yarns delimiting the outer planes of the fabric.

The use of weft yarns of different thicknesses is not in itself new. This has been applied in U.S. Patent No. 3,216,893, however, in that the metallic weft yarn has been used alternately with the plastic weft yarn as a flat weave, i.e., one yarn over the other underneath. The plastic weft yarn has then been thicker. All the brushes of the warp knees are thus brought to the same level on both sides of the fabric. The purpose has been to achieve the so-called single-layer construction on both sides of the fabric. Ko. the plane is then formed only from the knees of the warp yarns. However, this structure is completely different from the purpose of the present invention. U.S. Patent No. 3,523,867, in turn, uses thinner yarns as reinforcement adjacent to the warp yarns. The fabric for a flat wire machine according to U.S. Patent No. 1,616,222 has thicker warp and weft yarns at specified distances of 11,576,23. This is intended to change the drying properties of the fabric when making watermark paper. However, neither of the above methods corresponds to the present invention.

The main object of the invention is to provide a fabric for use in a flat wire machine which is relatively non-uniform in tread and better in wear resistance and service life than before.

The drying fabric according to the invention is characterized in that the transverse yarns vary in diameter with the diameter of some yarns being larger than the diameter of the intervening yarns, the minimum difference between larger and smaller transverse yarns being at least 10% of the smaller are deeper than the imaginary surface formed by the ridge points of the larger diameter transverse yarn knees, and that the smaller diameter transverse yarn knee ridge points on the tread side of the fabric are deeper than the imagined surface with the larger diameter transverse yarn knee forming knees. Preferred embodiments of the invention are defined in more detail in claims 2-5.

The invention will now be described with reference to the accompanying drawings, in which Figure 1 is a perspective view of a flat fabric machine fabric fabricated and preferred according to the invention, Figure 2 is an enlarged portion of the tread of Figure 1, Figure 3 is a section along plane 3-3 of Figure 2; along the plane i + —i * in Figure 2.

Figure 1 shows a fabric 1 of a flat wire machine formed by joining together the opposite ends of a fabric woven to a certain length from a seam 2. The width of the finished fabric can be about 9 m, even more. The length of the uniform web formed by the fabric can be about 5 .mu.m. The dimensions of the fabric depend on the paper machine for which it is woven, so the dimensions presented here are for illustrative purposes only. The upper surface of the fabric 1 shown in Figure 1 is its actual papermaking surface. The paper fiber mixture is fed to one end thereof. The inside of the fabric 1 is again its actual tread, which passes through the rollers and suction boxes of the machine and, in addition to the smaller lower rollers previously used in more modern machines. The fabric 1 moves forward at a considerable speed and water is absorbed from the pulp through the fabric, whereby the fibers form a paper web (initial web). By adjusting the flow of water through the fabric, the fabric then also moves in the transverse direction of the machine (shaking movement) - the fibers 5 S7623 are directed to different parties, with a large part of them becoming parallel to the transverse direction of the machine. This creates a paper web with good endurance in all directions. When the rolls, the parts of the previously used small lower rollers and the suction boxes are arranged in a suitable ratio to each other, the amount of water leaving the pulp through the fabric can be adjusted to suit, which facilitates the formation of the paper web.

Figure 2 shows a part of the tread of the fabric 1 enlarged. The warp yarns, i.e. the machine direction yarns 3, run there vertically, i.e. from top to bottom. When the fabric 1 is made as a continuous web as shown in Fig. 1, the warp yarns 3 extend along the entire length of the web in the longitudinal direction of the machine, i.e. in the direction in which the fabric 1 moves through the rollers and other parts of the flat wire machine.

The thickness of the weft yarns shown in Fig. 2, i.e. the yarns transverse to the machine, varies alternately so that the weft yarns U are relatively thick and the weft yarns 5 are thinner. The warp yarns 3, on the other hand, are equally thick throughout. The warp yarns 3 and the weft yarns U, 5 are woven in four rivets with a pattern of 1-2-3-¾. Thus, in each group of four adjacent warp yarns 3, the first warp yarn passes under the first weft yarn, the second warp yarn passes again under the next weft yarn, the third warp yarn passes under the next weft yarn and the fourth warp yarn again goes under the next weft yarn. This gives a kind of action effect. Nelinite weaving is also performed in the so-called as a satin pattern in which the order of the warp yarns varies 1-3-2-¾, and the so-called as a full-weave weave, in which each warp yarn passes first over two weft yarns and then under the two weft yarns, the subsequent warp yarns being staggered on a separate weft yarn.

Figure 3 shows a part of a warp yarn 3 passing over two thick weft yarns ¾ and one thin weft yarn 5 and then under one thin weft yarn 5 in a repeating pattern.

The figure ¾ shows a part of the adjacent warp yarn 3 passing over two thin weft yarns 5 and one thick weft yarn ¾ and then under one thick weft yarn ema as a repeating pattern. In both Figs. 3 and ¾, the papermaking side of the fabric 1 is upward and the tread contacting the rolls and the like is downward.

In the weaving from which Figures 2-¾ are taken, 79 warp yarns and 56 weft yarns per inch were used. The thickness of the warp yarn was 0.20 mm, which is otherwise the typical thickness of the warp yarn with this normal fabric made with this mesh size. The thick weft yarns ¾ were 0.25 mm and the thin weft yarns 5 were again 0.20 mm. These weft yarn thicknesses correspond to 0.22 mm weft yarn, which would be a suitable thickness for the above mesh size (79 warp yarns and 56 weft yarns per inch). The size of the thicker weft yarns was then increased from the normal thickness by approximately the same amount as 6,576,223 as the thinner weft yarns were reduced from the normal value. Therefore, the surface area of the "open" meshes of the present embodiment corresponds to the surface area of the meshes of fabrics of the same mesh. for the manufacture of fabrics for flat wire machines, without any substantial change in other related factors.

As the warp yarns 3 and the weft yarns b and 5, polyester is preferably used in the fabric shown in Figs. 1-1 *. As already mentioned above, other synthetic materials can also be used, for example nylon, acrylics and copolymers 1. copolymers. Metal wires, coated metal wires, and combinations of these different wire materials can be used to practice the invention.

In this case, however, the surface of the fabric must be kept uneven.

Figures 3 and 1 * are only schematic drawings, since when the yarns are subjected to hard compression, some physical changes take place in them, especially in the case of binding points and knees. However, such changes are not shown in the figure. However, it can be seen from the figures that the points determined in the thicker weft yarn U are in a different plane than the corresponding points in the thin weft yarn 5 · In addition, the knee points of the warp yarns below the thin weft yarn 5 on the bottom of the fabric are in a different plane than the warp yarn knees 7 passing under the thick weft yarn h. Measurements have shown that on the actual wear side of the fabric 1, part of the knees of the thick weft yarns U form the lowest points of the tread. Thus, they delimit the imaginary outer surface and at the same time its thickness. Moving inwards from the imaginary outer surface, or Figures 3 and U upwards, the next "oncoming" yarn surface is part of the knees of the thin weft yarns 5. Next, the higher yarn surface in the fabric 1 is formed by the warp yarn knees 7, which go under the thick weft yarns U. And even deeper in the fabric 1 are the warp yarn knees 6, which go under the thin weft yarns 5. The levels formed in the fabric may differ from the results of the above measurements, but since weft yarns of different thicknesses have been used alternately in the fabric 1, the tread formed therein, delimited by different yarn surfaces, is relatively uneven or non-uniform.

The greatest wear is on the thick weft yarns U, which have long protruding knees on the tread of the fabric. On the other hand, the thin weft yarns 5 wear less because they are inner and also have a smaller surface area. The warp yarns 3 only wear out again after the fabric has been used for a long time. The long service life of the fabrics according to the invention probably depends on the fact that the wear is "transferred" to a very large extent only to T 57623 in some weft yarns. Another factor may also be that the unevenness of the tread reduces the suction power of the fabric 1 as it passes over the suction boxes and other parts of the machine, thereby reducing the compression between the surfaces of the fabric and the suction boxes and other parts. In any case, the result is that the abrasion wear of the fabric is reduced and the service life is longer. In addition, it is also possible to present a theory that the water flow to the lower parts of the fabric 1 changes due to the unevenness of the tread of the fabric, whereby the bottom surfaces of the yarns are washed or a liquid film is formed as they move over the suction box and other machine parts. This may improve "lubrication" which in turn increases the life of the fabric. In any case, the invention improves the use properties of the fabric.

Since the ridges 6 and 7 of the warp knees are "lifted" into the fabric, the waviness of the warp knees decreases and since the warp knees thus remain lower, the warp yarns 5 cannot stretch as easily as the steep knees when tightened. The fabric 1 then remains easier to remain unchanged in size. However, the knees of the warp yarns are deep and curved enough so that they lock well enough in the weft yarns 4 And 5 · The fabric will not become too thin.

According to the construction described above, an uneven surface is obtained in the fabric of the flat wire machine by using Indel yarns of different thicknesses. When the invention has been applied in practice, the thinner weft yarns have usually been thinner than the weft yarns of normal fabric, while the thicker weft yarn has been thicker than the normal weft yarn. In this case, the mesh area of the fabric does not change much and the water permeability of the fabric also seems to remain the same compared to previous fabrics of a similar type. In contrast, the total number (volume) of weft yarns increases somewhat, which may have some effect on po. for better abrasion resistance of the fabric.

The thickness of the weft yarns preferably alternates so that the adjacent yarns on one side of the fabric are in different planes. This unevenness of the yarn planes of the fabric is coupled to the even mutual distance of adjacent yarns over the entire surface of the fabric. When this non-uniform surface is used as a tread, the service life of the fabric is extended. However, the reason for this is not fully known. However, it can be assumed that the flow of water through the fabric changes mainly at the lower surface of the fabric, which passes over the suction boxes, rollers, etc. of the machine. Water may now more easily flow along the tread of the fabric and form a film that "lubricates" the yarns, which in turn reduces their abrasion wear. This may also be due to the fact that the use of partially thicker weft yarns results in larger treads that extend the life of the fabric. Because po. however, the exact nature of the phenomena is not known, these assumptions should not be construed as limiting the invention in any way.

The difference between the diameter of the thick and thin weft yarn should be at least $ 10 for the thickness of the 8,576,23 thinner yarn. Admittedly, the difference can be as much as 30, although the upper limit may undoubtedly vary from application to application. The warp yarn is assumed to be of equal thickness throughout the fabric, taking into account the dimensions of the above-mentioned weft yarns. However, this need not be a limitation in the practice of the invention. Likewise, the special fabric described herein need not form a limiting factor as long as it is inconsistent. an uneven surface texture is obtained.

Claims (5)

9,57623 A drying fabric for use in a flat wire machine made of interwoven machine direction yarns (3) and transverse yarns (U, 5), these yarns (3, ^, 5) being woven into a four-line weave pattern, the transverse yarns (U, 5) being fully synthetic the material and the machine direction yarns (3) are either fully synthetic material or metal or metal coated yarns, characterized in that the transverse yarns (i *, 5) vary in diameter, with some yarns (U) having a larger diameter than the other intermediate yarns (5). ) diameter, the minimum difference between the diameters of the larger (U) and smaller (5) transverse yarns being at least 10% of the smaller transverse diameter, so that the ridge points (6,7) of the knees of the machine direction yarns (3) are deeper than the imaginary surface, formed by the ridge points of the knees of the larger diameter transverse yarns (U), and that p the ridge points of the knees of the larger diameter transverse yarns (5) on the tread side of the fabric are deeper than the imaginary surface formed by the ridge points of the larger diameter transverse yarns (M knees on the tread side). Paper machine drying fabric according to claim 1, characterized in that the ridge points (6) of the knees of the machine direction yarns (3) on the tread side of the fabric are deeper in the fabric than the knee ridge points of the smaller diameter transverse yarns (5). Paper machine drying fabric according to Claim 1 or 2, characterized in that the machine-oriented yarns (3) have substantially the same diameter. 1 ». Paper machine drying fabric according to one of Claims 1 to 3, characterized in that the diameter of each second transverse thread (U) is larger than the diameter of the alternating transverse yarn (5). Paper machine drying fabric according to one of Claims 1 to U, characterized in that each machine-direction yarn (3) passes around one transverse rib (U, 5) on the tread side of the fabric and then around three transverse ribs (U, 5) on the opposite side of the fabric and each transverse yarn (U, 5) passes around three machine direction yarns (3) on the tread side of the fabric and then around one machine direction yarn (3) on the opposite side of the fabric.