MXPA06011022A - Papermaker's forming fabric with machine direction stitching yarns that form machine side knuckles - Google Patents

Abstract

A papermaking fabric includes a series of repeat units, each of the repeat units including:a set of top machine direction (MD) yarns;a set of top cross machine direction (CMD) yarnsinterwoven with the set of top MD yarns;a first set of bottom CMD yarns, the first set of bottom CMD yarns arranged in pairs;a second set of bottom CMD yarns, the second set of bottom CMD yarns arranged as single yarns;a set of bottom CMD yarns interwoven with the first and second set of bottom MD yarns;and a set of pairs of MD stitching yarns interwoven with the top and bottom CMD yarns, each pair of MD stitching yarns sandwiching a respective immediately adjacent bottom MD yarn of the second set. Each of the yarns of a pair of the first set of bottom MD yarns interweaves with the bottom CMD yarns in the same pattern.

Description

MANUFACTURING FABRIC OF PAPER WITH UNION STRIPS IN DIRECTION OF THE MACHINE FORMING KNUCKLES OF THE SIDE OF THE MACHINE FIELD OF THE INVENTION This application is directed generally to the manufacture of paper, and more specifically to fabrics used in papermaking.

BACKGROUND OF THE INVENTION In the conventional Fourdrinier papermaking process an aqueous pulp, or suspension of cellulosic fibers (known as the "paper supply") is fed into the upper part of the upper section of an endless woven wire belt and / or synthetic material that It moves between two or more rollers. The belt, often referred to as a "forming fabric", provides a papermaking surface on the top upper surface that operates as a filter to separate the cellulosic fibers from the paper material of the aqueous medium, thereby forming a wet paper web. . The aqueous medium is drained through mesh openings of the forming fabric which are known as drainage holes, by gravity or vacuum located on the lower surface of the upper section (ie the "machine side") of the fabric.

After leaving the forming section, the paper web is transferred to a press section of the paper machine where it passes through the nip rollers of one or more pairs of pressure rollers covered with another fabric, typically referred to as "felt press". Roller pressure removes additional moisture from the belt; Moisture removal often improves by the presence of a "wadding" layer of the press felt. The paper is then transferred to a dryer section for additional moisture removal. After drying, the paper is ready for processing and secondary packaging. As used herein, the terms machine direction ("MD") and machine transverse direction ("CMD") refer, respectively, to an address aligned with the direction of travel of the fabric of the paper manufacturer in the machine for making paper, and a direction parallel to the surface of the fabric and transverse to the direction of travel. Similarly, the directional references to the vertical direction of the yarns in the fabric (for example, above, below, top, bottom, bottom, etc.) assume that the papermaking surface of the fabric is the top of the fabric. The fabric and the side surface of the fabric machine is the bottom of the fabric. Typically, papermaking fabrics are manufactured as endless belts by one of two basic weaving techniques. In the first of these techniques the fabrics are woven flat by a flat weaving process, with their ends being joined to form an endless belt by any of a number of well-known joining methods, such as dismantling and re-weaving the ends together (which is commonly referred to as spliced) or sewn on a flap with pin stitching or a special back fold at each end and then looped in loops with pin stitching. A series of self-bonding machines are now commercially available, which for certain fabrics can be used to automate at least part of the joining process. In a manufacturer's web for flat woven paper, the batched yarns extend in the machine direction and the filling yarns extend in the transverse direction of the machine. In the second basic weaving technique, the fabrics are woven directly in the form of a continuous belt with an endless weaving process. In the endless weaving process, the curled yarns extend in the transverse direction of the machine and the filling yarns extend in the machine direction. Both methods of weaving described above are well known in the art, and the term "endless belt" as used herein refers to belts made by any method. Effective support for leaves and fibers are important considerations in papermaking, especially in the forming section of the papermaking machine, where the wet band is formed initially. Additionally, forming fabrics must demonstrate good stability when run at high speeds in papermaking machines, and preferably are highly permeable to reduce the amount of water retained in the band when transferred to the press section of the machine for paper. In both applications for handkerchief and fine paper (ie paper for use in quality printing, carbonization, cigarettes, electrical capacitors and the like), the papermaking surface comprises a wire mesh structure very finely or finely woven. Typically, finely woven fabrics such as those used in thin paper and tissue applications include at least relatively small diameter yarns in the machine direction or in the transverse direction of the machine. Unfortunately, however, such threads tend to be delicate, leading to a short surface life for the fabric. Moreover, the use of smaller yarns can adversely affect the mechanical stability of the fabric (especially in terms of resistance to bias, propensity to narrow and rigidity), which can negatively affect the life and performance of the fabric. . To combat these problems associated with fine woven fabrics, multi-layer forming fabrics with fine mesh yarns have been developed on the paper-forming surface to facilitate the formation of paper and thicker mesh yarns on the contact side of the machine for Provide strength and durability. For example, fabrics have been constructed employing a set of yarns in the machine direction that are interwoven with two sets of yarns in the machine's transverse direction to form a fabric having a thin paper-forming surface and a yarn-like surface. the most durable machine. These fabrics are part of a class of fabrics that are generally known as "double layer" fabrics. Similarly, fabrics have been constructed that include two sets of yarns in the machine direction and two sets of yarns in the machine's transverse direction that form a side fabric layer of fine mesh paper and a side fabric layer. of the thickest and most separated machine. In these fabrics, which are part of a class of fabrics that are generally referred to as "triple layer" fabrics, the two fabric layers are typically joined together by separate bonding yarns. However, they can also be joined together using yarns from one or more of the yarn assembly in the machine direction and in the transverse direction of the lower and upper machine. Since double and triple layer fabrics include additional sets of yarns as compared to single layer fabrics, these fabrics typically have a "higher caliper" (i.e. are thicker) than comparable single layer fabrics. An illustrative double layer fabric is shown in U.S. Patent No. 4,423,755 to Thompson, and illustrative triple layer fabrics are shown in U.S. Patent No. 4,501, 303 to Osterberg, U.S. Pat. No. 5,152,326 to Vohringer, U.S. Patent No. 5,437,315 and 5,967,195 to Ward, and U.S. Patent No. 6,745,797 to Troughton. U.S. Patent No. 6,896,009 and copending and coassigned US Patent Application Serial No. 11 / 207,277, filed on August 18, 2005, describe a series of example multilayer forming fabrics having "bulging" union. " In some cases such fabrics may be easier to manufacture than weft forming fabrics and / or may have desirable performance properties. However, there is still a demand for additional types of domed fabrics that meet the wide variety of papermaking needs.

BRIEF DESCRIPTION OF THE INVENTION As a first aspect, embodiments of the present invention are directed to a papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of upper MD yarns; a set of upper CMD yarns interwoven with the set of upper MD yarns; a first set of lower MD yarns, the first set of lower MD yarns are arranged in pairs; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of pairs of MD bond yarns interwoven with the upper and lower CMD yarns, each pair of MD bond yarns housing thereon a corresponding immediately adjacent lower MD yarn of the second set. Each of the yarns of a pair of the first set of lower MD yarns is interwoven with the lower CMD yarns in the same pattern. As a second aspect, embodiments of the present invention are directed to a papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of upper MD yarns; a set of upper CMD yarns interwoven with the set of upper MD yarns; a first set of lower MD yarns, the first set of lower MD yarns arranged in a pair; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of pairs of MD bond yarns interwoven with the upper and lower CMD yarns, each pair of MD bond yarns housing thereon a corresponding immediately adjacent lower MD yarn of the second set. Each of the yarns of a pair of the first set of lower MD yarns is interwoven with the lower CMD yarns in the same pattern. In addition, each pair of lower MD yarns of the first set is placed below an upper MD yarn. As a third aspect, embodiments of the present invention are directed to a papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of upper yarns in the machine direction (MD); a set of threads in the upper machine transverse direction (CMD) interwoven with the set of upper MD yarns; a first set of lower MD yarns, each of the yarns of the first set has a planar cross section; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of pairs of MD bond yarns interwoven with the upper and lower CMD yarns, each pair of MD bond yarns housing thereon a corresponding immediately adjacent lower MD yarn of the second set. As a fourth aspect, embodiments of the present invention are directed to a method for making paper, comprising the steps of: (a) providing a papermaking fabric, the fabric comprising: a set of upper MD yarns; a set of upper CMD yarns interwoven with the set of upper MD yarns; a first set of lower MD yarns, the first set of lower MD yarns arranged in a pair; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of pairs of MD bond yarns interwoven with the upper and lower CMD yarns, each pair of MD bond yarns housing therebetween a corresponding lower and immediately adjacent MD yarn of the second set; wherein each of the threads of a pair of the first set of lower MD yarns is interwoven with the lower CMD yarns in the same pattern; (b) depositing paper supply in the papermaking fabric; and (c) removing moisture from the papermaking supply.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top view of a repeating unit of a forming fabric in accordance with the embodiments of the present invention. Figure 2 is a top view of the repeating unit of the fabric of Figure 1. Figures 3A-3F are sectional views taken of threads in the direction of the example machine of the fabric of Figures 1 and 2. The figure 4 is a top view of a repeating unit of a forming fabric in accordance with other embodiments of the present invention. Figure 5 is a bottom view of the repeating unit of the fabric of Figure 4. Figures 6A-6F are sectional views taken of yarns in the direction of the example machine of the fabric of Figures 4 and 5. The figure 7 is a top view of a repeater unit of a forming fabric in accordance with further embodiments of the present invention. Figure 8 is a bottom view of the repeating unit of the fabric of Figure 7.

Figures 9A-9F are sectional views taken of threads in the direction of the example machine of the fabric of Figures 7 and 8. Figure 10 is a sectional view taken of a top example CMD yarn of the fabric of the Figures 7 and 8. Figure 11 is a section taken from an exemplary top CMD yarn of an alternative fabric embodiment employing lower MD yarns that are flattened in cross section.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described more in particular hereinafter with reference to the accompanying drawings. The invention is not intended to be limited by the illustrated embodiments; on the contrary, these methods are intended to fully and completely describe the invention for those skilled in the art. In the drawings, similar numbers refer to similar elements along the same. The thicknesses and dimensions of some components can be increased for clarity. Well-known functions or well-known constructions may not be described in detail for brevity and / or clarity. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed points. The terminology used here is for the purpose of describing particular modalities only and is not intended to limit the invention. As used here, the singular forms "a," "an," and "the" are intended to include the plural forms equally, unless the context clearly indicates otherwise. It will further be understood that the terms "comprise" and / or "comprising", when used in this description, specify in the presence of features, integers, steps, operations, elements and / or components manifested, but do not prevent the presence or addition of one or more features, integers, steps, operations, elements, components and / or groups thereof. Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as those understood by the person skilled in the art to which this invention pertains. It will also be understood that the terms, those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning within the context of the relevant technique and not interpreted in an idealized or overly formal manner unless the same is expressed here. Although the figures below show only individual repeating units of the fabrics illustrated there, those skilled in the art will appreciate that in commercial applications the repeating units shown in the figures would be repeated many times, both in the machine and machine direction of the machine, to form a large cloth suitable for use in a papermaking machine.

Now back to Figures 1-3F, there is illustrated a repeating unit of a forming fabric in accordance with embodiments of the present invention., will designate broadly with 10. Repeatable unit 10 includes three upper MD yarns 11-13, three pairs of MD 21 a, 21 -23a, 23b junction yarns, twelve upper CMD yarns 31-42, six matched lower MD yarns 51a , 51 b-53a, 53b, three unmatched lower MD yarns 61-63 and six lower CMD yarns 71-76. The interweaving of these threads is described below. As can be seen in figures 1 and 3E, each of the upper MD yarns 11-13 is interwoven with the upper CMD yarns 31-42 in a sequence "about 1 / under 1", in which the upper MD yarns 11- 13 pass through the upper CMD threads in odd numbers 31, 33, 35, 37, 39, 41 and under the upper CMD wires in even numbers 32, 34, 36, 38, 40, 42. As can be seen in Figure 1, each pair of connecting wires 21 a, 21 b-23 a, 23 b is located between two wires MD superiors. As can be seen in Figures 1, 3a and 3C, each of the pairs of link yarns 21a, 23b is combined to be like an individual yarn upon completion of the flat woven pattern on the upper surface of the fabric 10. More specifically , each of the connecting threads passes over three upper CMD threads of even numbers, with the threads designated with an "a" that passes over a set of three upper CMD threads of even numbers, and each of the threads of union designated with a "b" passes over a set of the remaining three higher CMD threads of even numbers. For example, the connecting yarn 21a passes over upper CMD yarns 36, 38 and 40 while passing under upper CMD yarns 35, 37, 39 and 41, and the binding yarn 21 b passes over upper CMD yarns 42, 32 and 34 while passing under upper CMD threads 41, 31, 33 and 35. Thus, as a whole the connecting threads 21a, 21b form a "composite" upper MD yarn following an overall "above 1 / low 1" in relationship with the upper CMD threads. The upper MD yarn "composite" thus formed passes over upper CMD yarns of even numbers, thus forming a flat woven pattern with the upper MD yarns at the top, or papermaking surface of the fabric 10. Each pair of yarns The junction is deviated from its pairs of junction threads by two higher CMD threads. This can be seen by analyzing Figure 1, where the joining wires 21a, 21b pass both below the upper CMD yarn 35 as they move between the upper and lower layers of the fabric 10. Moving upwards in Figure 1 and the connecting threads 22a, 22b, these threads both pass under the upper CMD yarn 33 (which is deviated from the upper CMD yarn 35 by two upper CMD yarns) as they move between the upper and lower layers. The lower layer of the fabric 10 is illustrated in Figure 2. The lower layer includes matched lower MD yarns 51a, 51b-53a, 53b, unmatched lower MD yarns 61-63, bond yarns 21a, 21b-23a, 23b and lower CMD threads 71-76. The matched lower MD yarns, which are located below a corresponding upper MD yarn, are interwoven as a pair with the lower CMD yarns in a "about 2 / low 1" sequence. For example, with reference to Figures 2, 3D and 3F, the lower MD yarns 51a, 51b pass over the lower CMD yarns 73, 74 under the lower CMD yarn 75, over the lower CMD yarns 76, 71 and under the CMD yarn. lower 72. Each unmatched lower MD yarn also follows a "about 2 / low 1" sequence as it is woven with the lower CMD yarns. For example, the unpaired lower MD yarn 61 passes over the upper CMD yarns 72, 73, under the lower CMD yarn 74, over the lower CMD yarns 75, 76 and under the lower CMD yarn 71 (see Figures 2 and 3B). The matched lower MD yarns, which are located below a corresponding upper MD yarn, are woven together as a pair with the lower CMD yarns in a repeating sequence "over 2 / under 1". For example, with reference to Figures 2, 3D and 3F, the lower MD yarns 51a, 51b pass over the lower CMD yarns 73, 74 under the lower CMD yarn 75, over the lower CMD yarns 76, 71 and under the CMD yarn. lower 72. Each unpaired lower MD yarn also follows a "about 2 / low 1" sequence as it is woven with the lower CMD threads. For example, the unpaired lower MD yarn 61 passes over the lower CMD yarns 71, 72, under the lower CMD yarn 73, over the lower CMD yarns 74, 75 and under the lower yarn CMD 76 (see figures 2 and 3B). Referring again to Figure 2, each pair of tie wires houses between them an unmatched bottom MD yarn (for example, the tie yarns 21 a, 21 b house the lower MD yarn 61 between them) and each tie yarn forms a knuckle under a lower CMD thread. As used here, "knuckle" refers to a portion of a thread that, when interwoven with other threads, passes over or under another thread, while a "float" refers to a portion of a thread that passes over underneath of multiple adjacent threads. Each knuckle formed by a connecting thread is placed on the side of a knuckle formed by the immediately adjacent unpaired lower MD yarn, such that each pair of unraised lower MD yarns and threads form pairs of knuckles similar to the pairs of knuckles. knuckles of the lower MD paired threads. For example, unpaired lower MD yarn 61 knuckles below the lower CMD yarns 71 and 74 (see Figures 3A-3C). The connecting thread 21 b forms a knuckle under the lower CMD yarn 71, and the binding yarn 21a forms a knuckle under the lower CMD yarn 74. Each pair of matched lower MD yarns is deviated from its adjacent unpaired lower MD yarn by a lower CMD thread. For example, the unmatched lower MD yarn 61 forms a knuckle under the lower CMD yarn 71 and the matched lower yarns 51a, 51b form knuckles under the lower yarn CMD 72. As a result, the knuckle pairs in the lower surface form a knuckle. diagonal on this one. A repeating unit of another fabric in accordance with the embodiments of the present invention is broadly designated 110 and illustrated in Figures 4-6F. The repeater unit 110 includes four upper MD yarns 111-114, four pairs of MD 121a, 121 b-124a, 124b, sixteen CMD upper yarns 131-146, eight matched lower MD yarns 151a, 151b-154a, 154b , four unmatched lower MD yarns 161-164 and eight lower CMD yarns 171-178. The interweaving of these threads is described below. As can be seen in Figures 4 and 6B, each of the upper MD yarns 111-114 is interwoven with the upper CMD yarns 131-146 in an "over 1 / low 1" sequence, in which the upper MD yarns 111- 114 pass over the odd upper CMD threads 131, 133, 135, 137, 139, 141, 143, 145 and under the upper CMD threads of even numbers 132, 134, 136, 138, 140, 142, 144, 146. As can be seen in FIG. see in Figure 4, each pair of tie wires 121a, 121b-124a, 124b is located between two upper MD yarns. As with the fabric binding yarns 10 described above, and as can be seen in Figures 4, 6D and 6F, each of the pairs of union yarns 121a-124b is combined to act as an individual yarn to complete the flat weave pattern on the upper surface of the fabric 110. More specifically, each of the joining yarns passes over four upper CMD yarns of even numbers, with the junction yarns designated with an "a" passing over a set of yarns. four upper CMD threads of even numbers and each of the junction threads designated with a "b" passing over a set of the remaining four upper CMD threads of even numbers. For example, the connecting yarn 121a passes over upper CMD yarns 142, 144, 146 and 132 while passing under upper CMD yarns 141, 143, 145, 131 and 133, and the binding yarn 121b passes over higher CMD yarns 134, 136, 138 and 140 while passing under upper CMD yarns 133, 135, 137 and 141. As a whole the junction yarns 121a, 121 h form a composite upper MD yarn that follows a global trajectory "over one / under one "while interweaving with the upper CMD threads. The composite upper MD yarns formed by the tie yarns pass over even-numbered upper CMD yarns, thus forming a flat woven pattern with the upper MD yarns on the upper, or papermaking, surface of the fabric 110. Each pair of junction yarns is deviated from its neighboring junction yarn pairs by 4 higher CMD yarns. This can be seen by analyzing Figure 4, where the joining wires 121a, 121b pass both below the upper CMD yarn 133 as they move between the upper and lower layers of the fabric 110. Moving downward from Figure 4 and the union wires 122a, 122b, these yarns both pass below the upper CMD yarn 137 (which is offset from the upper CMD yarn 133 by four upper CMD yarns) as they move between the upper and lower layers. The lower layer of the fabric 110 is illustrated in Figure 5. The lower layer includes matched lower MD yarns 151a, 151b-154a, 154b, unmatched lower MD yarns 161-164, pairs of junction yarns 121a, 121b- 124a, 124b and lower CMD threads 171-178. The matched lower MD yarns, which are located below a corresponding upper MD yarn, are interwoven as a pair with the lower CMD yarns in a "about 3 / low 1" sequence. For example, with reference to Figures 5, 6A and 6C, lower MD yarns 151 a, 151 b pass over the lower CMD yarns, 173, 174, 175, under the lower CMD yarn 176, over the lower CMD yarns 177, 178, 171 and under the lower CMD yarn 172. Each unpaired lower MD yarn also follows a "about 3 / low 1" sequence as it is woven with the lower CMD yarns. For example, unpaired lower MD yarn 161 passes over lower CMD yarns 178, 171, 172, under the lower CMD yarn 173, over the lower CMD yarns 174, 175, 176 and under the lower CMD yarn 177 (see figures 5 and 6E). Referring again to Figure 5, each pair of tie wires houses between them a lower unmatched MD yarn (for example, tie wires 121a, 121b harbor the lower MD yarn 161). Each tie yarn forms a knuckle under a lower CMD yarn on one side of a knuckle formed by the immediately adjacent unpaired lower MD yarn, such that each pair of unraised lower MD yarns and threads form pairs of knuckles similar to paired knuckles of the paired lower MD threads. For example, unpaired lower MD yarn 161 forms knuckles below the lower CMD yarns 173 and 177 (see Figure 6E). The connecting yarn 121a forms a knuckle under the lower CMD yarn 173, and the binding yarn 121 b forms a knuckle under the lower yarn CMD 177 (see Figures 6D and 6F). Each pair of matched lower MD yarns is misaligned from its attached unpaired lower MD yarn by a lower CMD yarn. For example, an unmatched lower MD yarn 161 forms a knuckle under the lower CMD yarn 173, and paired lower yarns 151a, 151b form knuckle under the lower CMD yarn 172. As a result, the knuckle pairs in the lower surface form a diagonal in them.

As can be seen that, in the illustrated embodiment, the lower MD yarns "a" paired are smaller in diameter than the lower MD yarns "b" paired. It may be desirable in some embodiments for the threads "a" to match the diameter of the threads, so that the paired knuckles of (a) the matched lower MD yarns and (b) the paired knuckles of the lower MD yarns unpaired and the union wires have the same dimension. Those skilled in the art will appreciate that, in other embodiments (such as those of Figures 1-3F and Figures 7-9F), the lower MD yarns "a" and "b" may have the same diameter. A repeating unit of an additional fabric in accordance with the embodiments of the present invention is denoted broadly at 210 and illustrated in Figures 7-9F. The repeater unit 210 includes five upper MD yarns 211-215, five pairs of MD 221a, 221b-225a, 225b yarns, twenty upper CMD yarns 231-250, ten matched lower MD yarns 251 a, 251 b-255a, 255b , five unmatched lower MD yarns 261-265, and ten lower CMD yarns 271-280. The interweaving of these threads is described below. As can be seen in Figures 7 and 9B, each of the upper MD yarns 211-215 is interwoven with the upper CMD yarns 231-250 in an "over 1 / under 1" sequence, wherein the upper MD yarns 211-215 pass over the upper CMD threads listed oddly 231, 233, 235, 237, 239, 241, 243, 245, 247, 249 and under the upper CMD threads numbered in the same way 232, 234, 236, 238, 240, 242 , 244, 246, 248, 250.

As can be seen in Figure 7, each pair of connecting yarn 221a, 221b-225a, 225b is located between two upper MD yarns. As the joining yarns of the fabrics 10 and 110 described above, and as can be seen in Figures 7, 9D and 9F, each of the pairs of union yarn 221a-225b is combined to act as a single yarn to complete the yarn. flat weave pattern on the upper surface of the fabric 210. More specifically, each of the joining yarns passes over five upper CMD yarns numbered in the same way, with the junction yarns designated with an "a" passing over a set of five upper CMD threads numbered in the same way, and each of the threads designated with a "b" pass over a set of the five upper CMD threads numbered in the same way remaining. For example, the tie yarn 221a passes over upper CMD yarns 250, 232, 234, 236, and 238 while passing under the upper CMD yarns 249, 231, 233, 235, 237, and 239, and the bond yarn 221b passes over the upper CMD yarns 240, 242, 244, 246 and 248 as they pass under the upper CMD yarns 239, 241, 243, 245, 247 and 249. Together the joining yarns 221 a, 221b form an upper MD yarn of mixed material that follows a total path "over 1 / under 1" while interweaving with the upper CMD threads. The upper MD yarns of mixed material formed by the binding yarns pass over higher CMD yarns numbered in the same way, thus forming a flat woven pattern with the upper MD yarns in the upper part, or a papermaking surface of the fabric 210 Each pair of bond yarns is misaligned from their pairs of attached junction yarns by two upper CMD yarns. This can be seen from the examination of Figure 7, where the joining wires 221a, 221 b both pass under the upper CMD yarn 239, as it moves between the upper and lower layers of the fabric 210. Moving downward in 7 and to the connecting yarns 222a, 222b, these yarns both pass under the upper CMD yarn 241 (which is misaligned from the upper CMD yarn 239 by two upper CMD yarns) as they move between the upper and lower layers. The lower layer of the fabric 210 is illustrated in Figure 8. The lower layer includes paired lower MD yarns 251a, 251b-255a, 255b, unmatched lower MD yarns 261-265, pairs of union yarns 221a, 221 b-225a, 225b and lower CMD yarns 271-280. The matched lower MD yarns, which are located under a corresponding upper MD yarn, are interwoven as a pair with the lower CMD yarns in a "about 4 / low 1" sequence. For example, with reference to Figures 7, 9A and 9C the lower matted MD yarns 251a, 251 b pass over the lower CMD yarns 271-274, under the lower CMD yarn 275, over the lower CMD yarns 276-279 and under the lower CMD yarn 280. Each unmatched lower MD yarn also follows a "about 4 / low 1" sequence as it is woven with the lower CMD yarns. For example, an unpaired lower MD yarn 261 passes over the lower CMD yarns 271, 272, under the lower CMD yarn 273, over the lower CMD yarns 274-277, under the lower CMD yarn 278, and over the lower CMD yarns 279 , 280 (see figures 8 and 9E). Referring again to FIG. 8, each pair of tie yarns interspersed a non-paired bottom MD yarn (for example, the tie yarns 221a, 221b interspersed the lower MD yarn 261). Each knitting yarn forms a knuckle under a lower CMD yarn together with a knuckle formed by the immediately adjacent unpaired lower MD yarn, so that each pair of bond yarn and the unmatched lower MD yarns form pairs of knuckles similar to the knuckles. paired knuckles of the paired lower MD threads. For example, unpaired lower MD yarn 261 knuckles under the lower CMD yarns 273 and 278 (see Figure 9E). The connecting thread 221 b forms a knuckle under the lower CMD thread 273, and the connecting thread 221a forms a knuckle under the lower CMD thread 278 (see Figures 9D and 9F). Each pair of matched lower MD yarns is misaligned from its attached lower matched MD yarns by a lower CMD yarn. For example, the matched lower MD yarns 251a, 251b pass below the lower CMD yarn 275 and the matched lower MD yarns 252a, 252b pass under the lower CMD yarn 276, which is offset from the lower yarn CMD 276 by a lower CMD yarn. Each unmatched lower MD yarn is also misaligned from its attached unpaired lower MD yarn by a lower CMD yarn. For example, an unmatched lower MD yarn 261 forms a knuckle under the lower CMD yarn 273, and the unpaired lower yarn CMD 262 forms a knuckle under the lower CMD yarn 274, which is misaligned from the lower CMD yarn 273 by a CMD yarn. lower. As a result, the pairs of knuckles formed by the lower MD yarns matched on the lower surface form a diagonal therein, and the pairs of knuckles formed by an unpaired lower MD yarn and a connecting yarn form a second diagonal in the lower surface. The knuckles formed by the matched lower MD yarns are misaligned from the knuckles formed by an unmatched lower MD yarn and a bond yarn is offset from each other by two lower CMD yarns. As can be seen in Figure 10, the matched lower MD yarns 251a, 251b-255a, 255b are woven together with the lower CMD yarns 271-280. As such, in some embodiments the matched lower MD yarns can be replaced by a single lower MD yarn of the flattened cross section. This replacement is illustrated in Figure 11, wherein the matched lower MD yarns 251a, 251 b-255a, 255b of the fabric 200 are replaced with the lower MD yarns 351-355 in a fabric 300. The knitting pattern of the fabric 300 may be the same as that of fabric 200, except that the flattened lower MD yarns 351-355 follow the paths of the lower MD yarn pairs 251a, 251b-255a, 255b (see exemplary lower thread CMD 371). A similar substitution of the flattened yarns for the paired lower MD yarns can be made in other fabric embodiments described herein. Typically, the flattened yarn will have a height similar to that of the lower MD yarn for which it is replaced and a width similar to that of the two lower MD yarns for which it is substituted.

The shape of the yarns used in the fabrics of the present invention may vary, depending on the desired properties of the final paper-forming fabric. For example, the yarns can be monofilament yarns, monofilament yarns flattened as described above, multifilament yarns, twisted yarns or twisted monofilaments, yarns spun, or any combination thereof. Also, the materials comprising yarns employed in the fabric of the present invention may be those commonly used in the papermaking fabric. For example, the yarns may be formed of polyester, polyamide (nylon), polypropylene, aramid, or the like. Those skilled in the art should select a yarn material in accordance with the particular application of the final fabric. In particular, round monofilament yarns formed of polyester or polyamide are preferred. Fabrics such as those illustrated above can demonstrate improved stitching resistance compared to similar prior fabrics, which may allow the use of fewer ends to join the fabric. Also, increases in the open area of the fabric and / or permeability can be achieved. In accordance with another aspect of the present invention, methods for making paper are provided. According to these methods, one of the exemplary papermaking forming fabrics described herein is provided, and the paper is then made by applying a supply of paper to the forming fabric and subsequently removing moisture from the paper supply. . As the details of how the supply of paper is applied to the forming fabric and how moisture is removed from the paper supply is well understood by those skilled in the art, further details regarding this aspect of the present invention need not be provided in the present. The above embodiments are illustrative of the present invention, and are not construed as limiting thereof. Although exemplary embodiments of the invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without departing materially from the novel teachings and advantages of the invention. Also, said modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims included therein.

Claims (21)

NOVELTY OF THE INVENTION CLAIMS

1. - A papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of upper machine direction yarns (MD); a set of upper cross machine direction yarns (CMD) interwoven with the upper MD yarn set; a first set of lower MD yarns, the first set of lower MD yarns arranged in pairs; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of MD link yarn pairs interwoven with the upper and lower CMD yarns, each pair of MD bond yarns by sandwiching a respective immediately adjacent lower MD yarn of the second set; characterized in that each of the yarns of a pair of the first set of lower MD yarns are interwoven with the lower CMD yarns in the same pattern.

2. The papermaking fabric according to claim 1, further characterized in that the yarns of the first set of lower MD yarns form knuckles under the individual lower CMD yarns.

3. - The papermaking fabric according to claim 2, further characterized in that the yarns of the first set of lower MD yarns pass over between 2 and 4 lower CMD yarns between the knuckles formed under the lower CMD yarns.

4. The papermaking fabric according to claim 1, further characterized in that the yarns of the second set of lower MD yarns form knuckles under the individual lower CMD yarns.

5. The papermaking fabric according to claim 4, further characterized in that the yarns of the first set of lower MD yarns form knuckles under the individual lower CMD yarns.

6. The papermaking fabric according to claim 4, further characterized in that the yarns of the second set pass between 2 and 4 lower CMD yarns between the knuckles formed under the lower CMD yarns.

7. The papermaking fabric according to claim 4, further characterized in that each joint yarn forms a knuckle under a lower CMD yarn.

8. The papermaking fabric according to claim 7, further characterized in that each knitting yarn knuckle is formed under the lower CMD yarn under which the immediately adjacent lower yarn CMD of the second set forms a knuckle.

9. - The papermaking fabric according to claim 1, further characterized in that the upper MD yarns, the binding yarns, and the upper CMD yarns are woven together to form a common woven papermaking surface.

10. A papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of upper machine direction yarns (MD); a set of upper cross machine direction yarns (CMD) interwoven with the upper MD yarn set; a first set of lower MD yarns, the first set of lower MD yarns arranged in pairs; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of MD link yarn pairs interwoven with the upper and lower CMD yarns, each pair of MD bond yarns by sandwiching a respective immediately adjacent lower MD yarn of the second set; characterized in that each of the threads of a pair of the first set of lower MD yarns is interwoven with the lower CMD yarns in the same pattern; and wherein each pair of lower MD yarns of the first set is placed under an upper MD yarn.

11. The papermaking fabric according to claim 10, further characterized in that the yarns of the first set of lower MD yarns form knuckles under the individual lower CMD yarns.

12. The papermaking fabric according to claim 11, further characterized in that the yarns of the first set of lower MD yarns pass over between 2 and 4 lower CMD yarns between the knuckles formed under the lower CMD yarns.

13. The papermaking fabric according to claim 10, further characterized in that the yarns of the second set of lower MD yarns form knuckles under the individual lower CMD yarns.

14. The papermaking fabric according to claim 13, further characterized in that the yarns of the first set of lower MD yarns form knuckles under the individual lower CMD yarns.

15. The papermaking fabric according to claim 13, further characterized in that the yarns of the second set pass between 2 and 4 lower CMD yarns between the knuckles formed under the lower CMD yarns.

16. The papermaking fabric according to claim 13, further characterized in that each connecting thread forms a knuckle under a lower CMD yarn.

17. The papermaking fabric according to claim 16, further characterized in that each knuckle of bond yarn is formed under the lower CMD yarn under which the immediately adjacent lower CMD yarn of the second set forms a knuckle.

18. The papermaking fabric according to claim 10, further characterized in that the upper MD yarns, the binding yarns, and the upper CMD yarns are woven together to form a common woven papermaking surface.

19. A papermaking fabric, comprising a series of repeating units, each of the repeating units includes: a set of threads in the direction of the upper machine (MD); a set of threads in the transverse direction of the upper machine (CMD) interwoven with the set of upper MD yarns; a first set of lower MD yarns, each of the yarns of the first set has a flattened cross section; a second set of lower MD yarns, the second set of lower MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of MD link yarn pairs interwoven with the upper and lower MD yarns, each pair of MD bond yarns by sandwiching a respective immediately adjacent lower MD yarn of the second set.

20. A method for manufacturing paper, comprising the steps of: (a) providing a papermaking fabric, the fabric comprising: a set of yarns in the direction of the upper machine (MD); a set of threads in the transverse direction of the upper machine (CMD) interwoven with the set of upper MD yarns; a first set of lower MD yarns, the first set of lower MD yarns arranged in pairs; and a second set of lower MD yarns, the second set of MD yarns arranged as individual yarns; a set of lower CMD threads interwoven with the first and second sets of lower MD yarns; and a set of MD link yarn pairs interwoven with the upper and lower CMD yarns, each pair of MD bond yarns by sandwiching a respective immediately adjacent lower MD yarn of the second set; wherein each of the threads of a pair of the first set of lower MD yarns are interwoven with the lower CMD yarns in the same pattern: (b) depositing paper supply in the papermaking fabric; and (c) remove moisture from the papermaking supply.

21. The method according to claim 20, further characterized in that each pair of lower MD yarns of the first set is placed under an upper MD yarn.