Multi-ply warp bonded forming fabrics for papermakers.

Abstract

To provide a forming fabric that makes paper-forming easier.SOLUTION: The forming fabrics include a series of repeat units. Each of the repeat units include a set of binding warp yarns including a first set of binding warp yarns and a second set of binding warp yarns, where a binding warp yarn from the first set is paired with a binding warp yarn from the second set; a set of spring warp yarns, where each spring warp yarn is between a first pair of binding warp yarns and a second pair of binding warp yarns; a set of top weft yarns including odd and even top weft yarns, where the top weft yarns interweave with the binding warp yarns and the spring warp yarns to form a top fabric layer, where the spring warp yarns interweave only with the top weft yarns; a set of bottom weft yarns; and a set of bottom warp yarns, with the bottom warp yarns interwoven with the bottom weft yarns to form a bottom fabric layer.SELECTED DRAWING: None

Description

[Technical field]

[0001] [Related Applications] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 901,937, filed September 18, 2019, the entire disclosure of which is incorporated herein by reference.

[0002] This invention relates generally to papermaking, and more particularly to fabrics used in papermaking. [Background technology]

[0003] In a conventional Fourdrinier papermaking process, an aqueous slurry or suspension of cellulose fibers (known as the paper "stock") is fed onto the top of an endless belt of woven wire and / or synthetic material moving between two or more rolls. This belt, called a "forming fabric," provides a papermaking surface on the top of its top tier that acts as a filter to separate the cellulose fibers of the paper stock from the aqueous medium, thereby forming a moist paper web. The aqueous medium is drained through mesh openings in the forming fabric, known as drainage holes, by gravity or by a vacuum located on the underside (i.e., "machine side") of the top tier of fabric.

[0004] After leaving the forming section, the paper web is transferred to the press section of the papermaking machine where it passes through the nip of one or more pairs of pressure rolls, typically covered with another fabric called a "press felt." Pressure from the rolls removes additional moisture from the web. Moisture removal is enhanced by the presence of a "batt" layer in the press felt. The paper is then transferred to the dryer section for further moisture removal. After drying, the paper is prepared for secondary processing and packaging.

[0005] As used herein, the terms machine direction ("MD") and cross-machine direction ("CMD") refer, respectively, to the direction aligned with the direction of movement of a papermaking fabric on a papermaking machine and the direction parallel to the surface of the fabric and transverse to the direction of movement. Similarly, designations of directions relative to the perpendicular relationship of the yarns of the fabric (e.g., above, below, upper, lower, bottom, etc.) assume that the papermaking surface of the fabric is the top of the fabric and that the machine side of the fabric is the bottom of the fabric.

[0006] Typically, papermaker's fabric is manufactured as an endless belt by one of two basic weaving techniques. In the first technique, the fabric is woven in a plain weave process and the ends are joined to form an endless belt. This is done by any of a number of well-known joining methods, such as by undoing and reweaving the ends (commonly known as splicing), or by sewing in pin-seamable flaps or special turn-ups on both ends and then reweaving these into pin-seamable loops. Many automatic joining machines are now widely available and can be used to automate at least part of the joining process for certain fabrics. In a plain woven papermaker's fabric, the warp yarns run in the machine direction and the weft yarns run in the cross-machine direction.

[0007] In the second basic weaving technique, the fabric is woven directly in the form of a continuous belt with an endless weaving process. In the endless weaving process, the warp yarns run in the cross machine direction and the weft yarns run in the machine direction. Both of the above mentioned weaving methods are well known in the art and in this specification the term "endless belt" refers to a belt produced by either method. However, the formation and quality of the fabric at the edge of the loom limits the complexity of the weaves possible with the endless weaving process.

[0008] Effective sheet and fiber support is an important consideration in papermaking, especially for the forming section of the papermaking machine where the wet web is initially formed. The forming fabric must also exhibit good stability as it flows at high speeds over the papermaking machine, and is preferably highly permeable to reduce the amount of water retained by the web as it is transferred to the press section of the papermaking machine. In both tissue and fine paper applications (i.e., papers used in high quality printing, carbonization, tobacco, electrical capacitors, etc.), the papermaking surface is constructed of a very finely woven or fine wire mesh structure.

[0009] Typically, finely woven fabrics used in fine paper and tissue applications contain at least some relatively small diameter machine direction or cross machine direction yarns. Unfortunately, such yarns tend to be delicate and have a short surface life on the fabric. The use of smaller diameter yarns can also adversely affect the mechanical stability of the fabric (particularly in terms of skew resistance, narrowing propensity, and stiffness) and can adversely affect both the service life and performance of the fabric.

[0010] To address such problems associated with fine woven fabrics, multi-layer forming fabrics have been developed that use fine mesh yarns on the paper forming surface to facilitate paper forming and coarse mesh yarns on the machine contact side to provide strength and durability. For example, fabrics have been constructed that use one set of machine direction yarns interwoven with two sets of cross machine direction yarns to form a fabric with a fine paper forming surface and a more durable machine side. These fabrics form part of a class of fabrics commonly referred to as "two-layer" fabrics. Similarly, fabrics have been constructed that include two sets of machine direction yarns and two sets of cross machine direction yarns that form a fine mesh paper side fabric layer and a separate coarser machine side fabric layer. In these fabrics, which are part of a class of fabrics commonly referred to as "three-layer" fabrics, the two fabric layers are usually bonded together by separate stitching yarns. However, they may also be bonded together using yarns from one or more of the lower and upper cross machine direction and machine direction yarn sets. Because two- and three-ply fabrics contain an additional set of yarns compared to single-ply fabrics, these fabrics typically have a higher "caliper" (i.e., they are thicker) than comparable single-ply fabrics. Exemplary two-ply fabrics are shown in U.S. Patent No. 8,196,613 to Ward, and exemplary three-ply fabrics are shown in U.S. Patent No. 7,441,566 to Ward and U.S. Patent No. 7,059,357 to Ward. Summary of the Invention

[0011] In one aspect, the invention relates to a forming fabric, the forming fabric comprising a series of repeat units, each repeat unit comprising a set of binding warps including a first set of binding warps and a second set of binding warps, where the binding warps from the first set are paired with the binding warps from the second set, a set of spring warps, where each spring warp is disposed between the first pair of binding warps and the second pair of binding warps, a set of upper wefts including odd and even numbered upper wefts, where the upper wefts are interwoven with the binding warps and the spring warps to form an upper fabric layer, where the spring warps are interwoven only with the upper wefts, and where the first pair of binding warps are alternately offset by at least two upper wefts and then by at least four upper wefts to the second pair of binding warps. a set of lower warp threads, the lower warp threads being interwoven with the lower weft threads to form a lower fabric layer, wherein the binding warp threads and the spring warp threads from the first set and the second set are interwoven with the upper weft threads to relatively form a plain weave pattern in a determined zone such that (a) the first set of binding warp threads passes only over the odd-numbered upper weft threads, (b) the second set of binding warp threads passes only over the even-numbered upper weft threads, except that (c) the first binding warp thread of a pair is offset from the second binding warp thread of the pair by at least three upper weft threads to form an overlap in the warp thread paths of the pair of binding warp threads, and (d) each spring warp thread passes over both the even-numbered and odd-numbered upper weft threads, and the binding warp threads and the lower warp threads from the first set and the second set are interwoven with the lower weft threads.

[0012] In another aspect, the invention relates to a forming fabric that includes a series of repeat units, each repeat unit including a set of binding warps including a first set of binding warps and a second set of binding warps, where the binding warps from the first set are paired with the binding warps from the second set, a set of spring warps, where each spring warp is between the first pair of binding warps and the second pair of binding warps, a set of spring warps, and a set of upper wefts, where the upper wefts are interwoven with the binding warps and the spring warps to form an upper fabric layer, where the spring warps are interwoven only with the upper wefts, and where the first pair of binding warps are interwoven with at least two upper wefts, then at least four upper wefts. a set of upper wefts, a set of lower wefts, and a set of lower warp threads that are alternately offset by a second pair of bonding warp threads to the second pair of bonding warp threads, where the lower warp threads are interwoven with the lower weft threads to form a lower fabric layer, and the bonding warp threads and the lower warp threads from the first and second sets are interwoven with the lower weft threads such that (a) each lower warp thread forms a plurality of knuckles along the lower fabric layer, (b) each bonding warp thread from the first set is interwoven with the lower warp threads under the lower weft threads to form a double knuckle, and (c) each bonding warp thread from the second set is interwoven with the lower warp threads under the lower weft threads to form a double knuckle.

[0013] In a further aspect, the invention relates to a forming fabric comprising a series of repeat units, each repeat unit comprising a set of binding warp threads including a first set of binding warp threads and a second set of binding warp threads, where the binding warp threads from the first set are paired with the binding warp threads from the second set, a set of spring warp threads, where each spring warp thread is between the first pair of binding warp threads and the second pair of binding warp threads, a set of spring warp threads, and a set of upper weft threads, where the upper weft threads are interwoven with the binding warp threads and the spring warp threads to form an upper fabric layer, where the spring warp threads are interwoven only with the upper weft threads, and where the first pair of binding warp threads are interwoven with the binding warp threads for at least four upper weft threads. a set of upper wefts, a set of lower wefts, and a set of lower warp threads offset to a second pair of the first set, where the lower warp threads are interwoven with the lower weft threads to form a lower fabric layer, and the bonding warp threads and the lower warp threads from the first set and the second set are interwoven with the lower weft threads such that (a) each lower warp thread forms a plurality of knuckles along the lower fabric layer, (b) each bonding warp thread from the first set is interwoven with the lower warp threads under the lower weft threads to form a double knuckle, and (c) each bonding warp thread from the second set is interwoven with the lower warp threads under the lower weft threads to form a double knuckle.

[0014] It should be noted that aspects of the invention described in an embodiment may be incorporated in different embodiments, even if not specifically described in this connection. That is, all embodiments and / or all features in any embodiment may be further combined in any manner and / or combination. Applicant reserves the right to modify the claims as originally filed and / or to file new claims accordingly, including the right to amend the claims as originally filed to depend on and / or incorporate features of other claims, even if not originally so claimed. These and other objects and / or aspects of the invention are described in detail herein below. Further features, advantages and details of the invention will be apparent to those skilled in the art upon reading the figures and the following detailed description of the preferred embodiments, such description being merely illustrative of the invention.

[0015] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication and any color drawing(s) will be provided by the Office upon request and payment of the necessary fee. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a top view showing one embodiment of a papermaking forming fabric according to the present invention. [Diagram 2] FIG. 2 is a bottom view of a repeat unit of the fabric of FIG. 1. [Diagram 3] FIG. 3 is a bottom view showing the fabric of FIG. 2. [Figure 4A] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of a first binding warp yarn for the fabric of FIG. [Figure 4B] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of second binding warp yarns for the fabric of FIG. [Figure 4C] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of spring warp yarns for the fabric of FIG. [Figure 4D] 2 is a cross-sectional view showing an exemplary weave pattern of adjacent bonding warp yarn pairs for the fabric of FIG. 1. [Figure 5A] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of the upper weft for the fabric of FIG. [Figure 5B] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of the upper weft for the fabric of FIG. [Figure 5C] FIG. 2 is a cross-sectional view showing an exemplary weave pattern of the upper weft for the fabric of FIG. [Figure 6] FIG. 2 is a bottom view illustrating an exemplary zigzag pattern of dual knuckles formed in the bottom fabric layer for the fabric of FIG. 1 in one embodiment of the present invention. [Figure 7] FIG. 2 is a bottom view illustrating exemplary floats (symmetric / asymmetric) of bottom weft yarns for the fabric of FIG. 1 in one embodiment of the present invention. [Figure 8]FIG. 2 is a top view of the fabric of FIG. 1 showing a plain weave zone in a paisley pattern and a surrounding zone formed in a top fabric layer. [Figure 9] FIG. 2 is a top view showing another embodiment of the papermaking forming fabric according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which embodiments of the present invention are shown. However, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0018] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

[0019] As used herein, the terms machine direction ("MD") and cross-machine direction ("CMD") refer, respectively, to the direction aligned with the direction of travel of a forming fabric on a papermaking machine and the direction parallel to and transverse to the direction of travel of the fabric surface. Similarly, designations of directions relative to the perpendicular relationship of the yarns of the fabric (e.g., above, below, upper, lower, bottom, etc.) assume that the papermaking surface of the fabric is the top of the fabric and that the machine side of the fabric is the bottom of the fabric.

[0020] Unless otherwise defined, all terms in this specification (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this invention belongs. Furthermore, terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formalized sense unless explicitly defined in this specification.

[0021] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly indicates otherwise. It is to be understood that as used herein, the terms "comprise" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0022] Spatially relative terms such as "below," "lower," "lower," "up," "above," "top," "middle," "bottom," etc. may also be used and are used herein to describe the relationship of one element or feature to another as shown in the figures for ease of description. It will be understood that the spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned upside down, elements described as "below" or "below" other elements or features would be oriented "above" those other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or otherwise oriented) and the spatially relative descriptors used herein interpreted accordingly.

[0023] Additionally, well-known functions or constructions may not be described in detail for the sake of brevity and / or clarity.

[0024] Next, embodiments of the present invention will be described in more detail with reference to the drawings, in which two-part reference numbers are sometimes used. In this specification, elements having such two-part reference numbers can be individually referred to by their complete reference numbers (e.g., warp thread 105-2) or collectively referred to by a portion of their reference numbers (e.g., warp thread 105).

[0025] Referring to the drawings, FIGS. 1-9 show a multi-layer papermaking forming fabric (broadly designated 100) in accordance with an embodiment of the present invention. FIG. 1 shows the paper side or "top" side 100a of fabric 100. FIG. 2 shows the repeat units on the machine side or "bottom" side 100b (i.e., the side that faces the papermaking machine) of fabric 100. FIG. 3 shows multiple repeat units on the bottom side 100b of fabric 100. Table 1, discussed below, also provides a legend for FIGS. 3, 6, 7, and 8.

[0026] The paper (top) side of the fabric 100 is formed of binding warp yarns, spring warp yarns, and top weft yarns. The top weft yarns and spring warp yarns are interwoven only on the paper side of the fabric 100. The machine (bottom) side of the fabric 100 is formed of binding warp yarns, bottom warp yarns, and bottom weft yarns. The top weft yarns and bottom warp yarns are interwoven only on the machine side of the fabric 100. The binding warp yarns are interwoven between the paper side and the machine side, binding the two layers of the fabric together to form the multi-layer papermaking forming fabric 100.

[0027] A papermaking forming fabric 100 according to the present invention can include a series of repeat units. In some embodiments, each repeat unit can include a set of binding warp yarns 102, a set of spring warp yarns 104, a set of upper weft yarns 106a, a set of lower weft yarns 106b, and a set of lower warp yarns 108, as shown in Figures 1-3.

[0028] In some embodiments, the set of combining warp yarns 102 includes a first set of combining warp yarns 102a and a second set of combining warp yarns 102b. The combining warp yarns 102a, 102b run side by side on the paper side of the fabric 100 and are separated by bottom warp yarns 108 (e.g., 108-1 through 108-6) on the machine side of the fabric 100. The first set of combining warp yarns 102a are offset in the warp direction from the second set of combining warp yarns 102b. This offset creates an overlap of both sets of combining warp yarns 102a, 102b. The combining warp yarns from the first set 102a are paired with the combining warp yarns from the second set 102b to form combining warp yarn pairs 103.

[0029] In some embodiments, the bonding warp yarns 102a, 102b of each bonding warp yarn pair 103 extend adjacent to one another in the upper fabric layer 100a and can be separated by one lower warp yarn 108 in the lower fabric layer 100b. In some embodiments, the first pair of bonding warp yarns 103a are alternately offset from the second pair of bonding warp yarns 103b by at least two upper weft yarns 106a and then at least four upper weft yarns 106a. The spring warp yarns 104 are disposed between the first pair 103a of bonding warp yarns 102a, 102b and the second pair 103b of bonding warp yarns 102a, 102b. The upper weft yarns 106a (e.g., 106a 1~12 ) are interwoven with binding warp yarns 102a, 102b and spring warp yarns 104 to form the top fabric layer 100a (i.e., the paper side of the fabric 100). The number of top pick yarns 106a per repeat unit can vary. In some embodiments, for example, if the forming fabric 100 has a 3:2 weft ratio, the top fabric layer 100a has 12 top pick yarns 106a per repeat unit (i.e., the paper side of the fabric 100). 1~12 In other embodiments, for example, if the forming fabric 100 has a 2:1 weft ratio, the upper fabric layer 100a may include 16 upper weft yarns 106a per repeat unit (i.e., 16 upper weft yarns 106a 1~16 In some embodiments, the first pair of binding warp yarns 103a are offset to the second pair of binding warp yarns 103b by at least four upper weft yarns 106a. 1~8) are interwoven with lower warp yarns 108 to form the bottom fabric layer 100b (ie, the machine side of the fabric 100).

[0030] In some embodiments, the first and second sets of binding warp yarns 102a, 102b, and spring warp yarns 104 are interwoven with top pick yarns 106a to relatively form a plain weave "1 above / 1 below" pattern in defined zones on the paper side of the fabric 100. In some embodiments, the plain weave of the defined zones is formed by: (a) a first set of binding warp yarns 102a interwoven with "odd" top pick yarns 106a (e.g., 106a1, 106a3, 106a5, 106a7, 106a9, 106a10, 106a20, 106a30, 106a40, 106a50, 106a60, 106a70, 106a80, 106a90, 106a10, 106a11, 106a12, 106a13, 106a14, 106a15, 106a16, 106a17, 106a18, 106a19, 106a20, 106a21, 106a22, 106a23, 106a24, 106a25, 106a26, 106a27, 106a28, 106a29, 106a30, 106a31, 106a32, 106a33, 106a34, 106a35, 106a36, 106a37, 106a38, 106a39, 106a41, 106a42, 106a43, 10 11 ), and (b) a second set of binding warp yarns 102b passes over only the “even” upper weft yarns 106a (e.g., 106a2, 106a4, 106a6, 106a8, 106a 10 , 106a 12 ), and (c) the first bonding warp thread 102a of the pair 103 of bonding warp threads 102a, 102b is offset from the second bonding warp thread 102b of the pair 103 by at least three upper weft threads 106a. This offset creates an overlap in the warp thread path of the pair 103 of bonding warp threads 102a, 102b.

[0031] 4A-4D show cross-sectional views of exemplary weave patterns that can be used to form the top and bottom fabric layers 100a, 100b of the papermaking forming fabric 100 in an embodiment of the present invention. As shown in FIGs. 4A-4D, the warp yarns (i.e., binding warp yarns 102a, 102b, spring warp yarns 104, and bottom warp yarns 108) can include segments that are interwoven with the weft yarns (106a, 106b) in a particular "over / under" sequence.

[0032] 4A, 4B, and 4D, in some embodiments, each lower warp yarn 108 can include a segment where the lower warp yarn 108 interweaves with the lower weft yarn 106b in a bottom1 / top1 / bottom1 order. In some embodiments, each combined warp yarn from the first and second sets 102a, 102b can include a segment where each combined warp yarn 102a, 102b interweaves with the upper weft yarn 106a in a top1 / bottom1 / top1 / bottom5 / top1 / bottom1 / top1 / bottom1 order (FIG. 4A) (e.g., in a fabric 100 with a weft ratio of 3:2). In some embodiments, each of the combined warp yarns from the first and second sets 102a, 102b can include a segment where each combined warp yarn 102a, 102b interweaves with the top weft yarn 106 in the following order (e.g., for a fabric 100 with a weft ratio of 2:1): Over1 / Down1 / Over1 / Down1 / Over1 / Down7 / Over1 / Down1 / Over1 / Down1. As shown in FIG. 4C, in some embodiments, each of the spring warp yarns 104 can include a segment where each of the spring warp yarns 104 interweaves with the top weft yarn 106a in the following order (e.g., for a fabric 100 with a weft ratio of 3:2): Over1 / Down1 / Over1 / Down4 / Over1 / Down1 / Over1 / Down2. Also, in some embodiments, each spring warp yarn 104 can include a segment in which the spring warp yarn 104 is interwoven with the top weft yarn 106a in the following order (e.g., for a fabric 100 with a weft ratio of 2:1): top 1 / bottom 2 / top 1 / bottom 1 / top 1 / bottom 1 / top 1 / bottom 4 / top 1 / bottom 1 / top 1 / bottom 1.

[0033] 5A-5C, in some embodiments, the upper fabric layer 100a can include a series of weft path repeat units 150. The weft path repeat unit 150 can include at least one first weft yarn 150a (e.g., FIG. 5A), at least one second weft yarn 150b (e.g., FIG. 5B), and at least one third weft yarn 150c (e.g., FIG. 5C). FIGS. 5A-5C show an exemplary weave pattern of an upper weft yarn 106a having warp yarns 105 (i.e., binding warp yarns 102a, 102b and spring warp yarns 104) in the upper fabric layer 100a. For example, as shown in FIG. 5A, in some embodiments, the first weft path 150a may include a segment in which the upper weft yarn 106a interweaves with the warp yarns 105 (e.g., 105-1 through 105-12) in the following order: Top 3 / Bottom 1 / Top 2 / Bottom 1 / Top 2 / Bottom 1 / Top 1 / Bottom 1. As shown in FIG. 5B, in some embodiments, the second weft path 150b may include a segment in which the upper weft yarn 106a interweaves with the warp yarns 105 (e.g., 105-1 through 105-12) in the following order: Top 3 / Bottom 1 / Top 2 / Bottom 1 / Top 1 / Bottom 1. Warp threads 5C, in some embodiments, the third weft path 150c may include a segment in which the upper weft 106a is interwoven with the upper weft 105 in the order of top 3 / bottom 1 / top 2 / bottom 1 / top 1 / bottom 1 / top 2 / bottom 1. Also, as shown in FIG. Warp threads 105 and interwoven segments in the order top 3 / bottom 1 / top 1 / bottom 1 / top 2 / bottom 1 / top 2 / bottom 1.

[0034] The spring warp threads 104 are interwoven only with the top weft threads 106a. In some embodiments, each spring warp thread 104 passes over the "even" and "odd" top weft threads 106a. In some embodiments, each spring warp thread 104 can include a segment where the spring warp thread 104 swings toward a first pair 103a of the combined warp threads 102a, 102b to push the first pair 103a of the combined warp threads 102a, 102b together. Each spring warp thread 104 can further include a segment where the spring warp thread 104 swings toward a second adjacent pair 103b of the combined warp threads 102a, 102b to push the second pair 103b of the combined warp threads 102a, 102b together (see, e.g., FIG. 1). In this way, each coupled warp thread pair 103a, 103b is supported on its left side by one spring warp thread 104 and on its right side by a different spring warp thread 104.

[0035] The pair of bound warps 103a, 103b in combination with one spring warp thread 104 on the left side and one spring warp thread 104 on the right side form a "paisley pattern" shaped plain weave zone 160 (see, for example, FIG. 8). These paisley pattern shaped plain weave zones 160 formed in the upper fabric layer 100a will be described in further detail below.

[0036] In some embodiments, a forming fabric 100 according to the present invention has a weft ratio of three top weft yarns 106a to two bottom weft yarns 106b (i.e., 3:2) (see, e.g., Figures 1-8). In some embodiments, a forming fabric 100 according to the present invention has a weft ratio of two top weft yarns 106a to one bottom weft yarn 106b (i.e., 2:1) (see, e.g., Figure 9).

[0037] As shown in FIG. 3, in some embodiments, the bonding warp yarns and the lower warp yarns 108 from the first and second sets 102a, 102b are interwoven with the lower weft yarn 106b such that (a) each lower warp yarn 108 forms a plurality of knuckles 122 along the lower fabric layer 100b, (b) each bonding warp yarn from the first set 102a is interwoven with the lower warp yarn 108 under the lower weft yarn 106b to form a first double knuckle 122, and (c) each bonding warp yarn from the second set 102b is interwoven with the lower weft yarn 106b that is not adjacent to the first bonding warp yarn 102a or is interwoven with the lower warp yarn 108 under the lower weft yarn 106b to form a second double knuckle 122 (see also, e.g., FIGS. 6-7). As used herein, a "double knuckle" refers to when two adjacent warp yarns (e.g., binding warp yarns 102a, 102b and bottom warp yarn 108) are bound side-by-side under the same bottom weft yarn 106b. In the figures, the double knuckle 122 or its location is highlighted with a white oval (see also, e.g., Table 1).

[0038] In some embodiments, at least one bottom weft yarn 106b separates a first double knuckle 122 formed by the bottom warp yarn 108 and a binding warp yarn from the first set 102a, and a second double knuckle 122 formed by the same bottom warp yarn 108 and a binding from the second set 102b (e.g., for a fabric 100 with a weft ratio of 3:2). This short float of the bottom warp yarn 108 under the at least one bottom weft yarn 106b and the placement of the double knuckle 122 can also provide the added benefit of anchoring the bottom weft yarn 106b, thereby helping to reduce or eliminate movement of the bottom weft yarn 106b. In some embodiments, these two double knuckles can be separated by two bottom weft yarns 106b.

[0039] 6, in some embodiments, the bottom warp yarn 108 that forms part of the first double knuckle 122b1 forms part of the third double knuckle 122a3, and the adjacent bottom warp yarn 108 that forms part of the second double knuckle 122b2 also forms part of the fourth double knuckle 122a4. This arrangement of the double knuckles 122 in the machine direction (i.e., two double knuckles 122 behind each other with at least one bottom weft yarn between) can provide additional stability in bending stiffness in this region of the four double knuckles 122 (i.e., the boxed region as shown in FIG. 6).

[0040] As shown in FIG. 6, in some embodiments, the arrangement of the dual knuckles 122 formed along the bottom fabric layer 100b can follow a type of zigzag pattern. In some embodiments, the zigzag pattern is formed by a first set of dual knuckles 122a formed on a first diagonal. 1~4 and a second set of double knuckles 122b formed on a second diagonal. 1~4 , where the second diagonal of the double knuckles 122b is offset from the first diagonal of the double knuckles 122a. Arranging the double knuckles 122a, 122b in a zigzag diagonal pattern on the machine side of the fabric 100 can provide improved diagonal (i.e., cross-machine) stability to the fabric 100 of the present invention. Additionally, this arrangement of the double knuckles 122a, 122b can help prevent the fabric 100 from drifting on the papermaking machine.

[0041] Also, referring to FIG. 7, in some embodiments, the lower weft yarn 106b-1 can provide additional support for a balanced extending direction. A short float of the lower warp yarn 108 under only one lower weft yarn 106b (see also FIG. 3 for example) pushes the lower weft yarn 106b (106b-1 and 106b-2) outwards, creating an asymmetric shape of the lower weft float. This asymmetric shape of the lower weft float can move to one side of the lower yarn float to create a wider contact area on the running side. The wear ellipse of this lower yarn float is also asymmetric (marked with a triangle on the lower yarn float in FIG. 7).

[0042] Due to the offset arrangement of the double knuckles diagonals, two different asymmetrical bottom weft yarn floats are alternately arranged in different directions adjacent to the end / beginning of the double knuckles diagonals to balance their asymmetry. The asymmetry of the bottom weft float 106b-1 will be balanced by the bottom weft yarn 106b-2, which has the opposite asymmetric shape of the bottom weft float. The other bottom weft yarns 106b-3 and 106b-4, which are woven under the double knuckles in the middle of the diagonals, combine with the warp yarns in a way to form a symmetrical bottom weft yarn float (marked with a rectangle at the bottom weft float in FIG. 7). In other embodiments, the bottom weft yarn 106b can have only asymmetrical bottom weft floats and alternate continuously (weft ratio 2:1).

[0043] For example, as shown in FIG. 7, in some embodiments, the portion of the float of the bottom weft yarn 106b to the right of the first double knuckles 122b1 and 122a1 has a larger contact area than the portion of the same bottom weft yarn 106b to the left of the first double knuckles 122b1 and 122a1. In some embodiments, the portion of the bottom weft yarn 106b to the left of the fourth double knuckles 122a4 and 122b4 has a larger contact area than the portion of the same bottom weft yarn 106b to the right of the fourth double knuckles 122a4 and 122b4. In some embodiments, the portions of the float of the bottom weft yarn 106b to the left and right of the diagonal second and third double knuckles 122a2, 122a3, 122b2, 122b3 have equal contact areas. Thus, in some embodiments, the bottom weft yarns 106b are arranged such that two bottom weft yarns 106b with symmetric floats (i.e., "rectangles") are followed by two bottom weft yarns 106b with asymmetric floats (i.e., "triangles") in the opposite direction, as shown in Figure 7. In some embodiments, alternating the direction of the asymmetric bottom weft floats and mixing them with the symmetric bottom weft floats helps address drift issues.

[0044] Referring to FIG. 8, a number of repeat units of the paper side as shown in FIG. 1 are shown to illustrate the effect of different weft path arrangements (FIGS. 5A-C). In some embodiments, the weft path repeat unit 150 may include segments of weft paths 150a-c (FIGS. 5A-C) arranged as follows: first weft path 150a, second weft path 150b, first weft path 150a, third weft path 150c, second weft path 150b, and third weft path 150c. Also, in some embodiments, the weft path repeat unit 150 may include segments of weft paths 150a-c arranged as follows: first weft path 150a, third weft path 150c, second weft path 105b, and second weft path 150b. The weft thread repeat unit 150 can vary depending on the weft ratio of the fabric 100. The weft thread repeat unit 150 can form special structures on the upper fabric layer 100a.

[0045] Part of such a structure is formed by the arrangement of float lengths of the upper weft yarn 106a on the two combined paper side warp yarns 102a, 102b occurring in the weft yarn paths 150a-c. The arrangement of floats on the two paper side warp yarns is arranged between the plain weave zones in the shape of a paisley pattern. This arrangement improves lateral stability and compensates for cross machine direction skew. In some embodiments, the area between the zones of the paisley pattern is smaller than and opposite to the first and second diagonals of the double knuckles 122 on the lower fabric layer 100b. In some embodiments, the repeat unit 150 of the weft yarn paths forms the upper fabric layer 100a without visible diagonals.

[0046] Another part of such a structure is the segments of the first, second and third weft yarn paths 150a-c, which pass through the three warp yarns of the upper fabric layer 100a aligned between the first and third double knuckles (e.g., 122b1 and 122a3), between the second and fourth double knuckles (e.g., 122b2 and 122a4), respectively, as well as at the diagonal drift of the double knuckles 122 formed on the lower fabric layer 100b. Such alignment of the longer upper weft yarns 106a floats on the three (or more) warp yarns helps to counteract the compression of the material found in prior art fabrics, which often leads to dewatering failures and markings on the paper.

[0047] In some embodiments, the first, second, and third weft yarn paths 150a-c segments passing through one warp yarn form the center of a paisley patterned plain weave zone 160 in the upper fabric layer 100a. Successive weft yarn path repeat units 150 form a continuous weave zone 160 in the upper fabric layer 100a. Mirror symmetric A paisley pattern shaped plain weave zone 160 is formed. As shown in Fig. 8, the paisley pattern shaped plain weave zone 160 formed on the upper fabric layer 100a is aligned between the diagonals (zigzag pattern) of the double knuckles 122 on the lower fabric layer 100b.

[0048] The placement of the fabric stitches in these paisley patterned zones 160 and the reduced mesh size in the top fabric layer 100a allows for optimization on fiber support points. The mesh also provides a support zone for the staple fibers of the papermaking machine. Furthermore, the reduced mesh size allows for smaller drainage channels, which helps to increase the flow rate of the aqueous medium during the papermaking process. The forming fabric 100 of the present invention is more closed on the paper side of the fabric and at the same time can have a very high flow rate.

[0049] As noted above, forming fabrics 100 according to the present invention can include different weft ratios. Figure 9 illustrates a forming fabric 100' in one embodiment of the present invention having a weft ratio of 2:1 (i.e., two top weft yarns 106a' to one bottom weft yarn 106b'). Other weft ratios can be incorporated into forming fabrics 100 according to the present invention. For example, in some embodiments, forming fabrics 100 can have a weft ratio of 1:1, 3:1, or 5:2.

[0050] The above description is illustrative of the present invention and should not be construed as limiting. Although exemplary embodiments of the present invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without substantially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be within the scope of the present invention, as set forth in the claims. The present invention is defined by the following claims, including equivalents thereto.

[0051] [Table 1]

Claims

1. 1. A forming fabric comprising a series of repeat units, each of the repeat units comprising: a bonding warp set including a first set of bonding warp yarns and a second set of bonding warp yarns, wherein the bonding warp yarns from the first set are paired with the bonding warp yarns from the second set; a set of spring warp yarns, each of the spring warp yarns having a spring elasticity and between the first pair of binding warp yarns and the second pair of binding warp yarns; a set of upper weft yarns, the upper weft yarns interwoven with the binding warp yarns and the spring warp yarns to form an upper fabric layer, the spring warp yarns interwoven only with the upper weft yarns, a first pair of binding warp yarns being offset in the warp direction relative to a second pair of binding warp yarns by at least two upper wefts, then by at least four upper wefts, alternating in the weft direction; Set the lower weft and a set of lower warp yarns, the lower warp yarns interwoven with the lower weft yarns to form a lower fabric layer; Including, the bonding warp yarns and the bottom warp yarns from the first and second sets are interwoven with the bottom weft yarns such that (a) each of the bottom warp yarns forms a plurality of knuckles along the bottom fabric layer, (b) each of the bonding warp yarns from the first set is interwoven with the bottom warp yarns under the bottom weft yarns to form double knuckles, and (c) each of the bonding warp yarns from the second set is interwoven with the bottom warp yarns under the bottom weft yarns to form double knuckles.

2. 2. The forming fabric of claim 1, wherein at least one lower weft is between a first double knuckle formed by the lower warp and a first bonding warp and a second double knuckle formed by the lower warp and a second bonding warp.

3. 3. The forming fabric of claim 1 or 2, wherein each of the spring warp yarns includes a segment in which the spring warp yarn is interwoven with the top weft yarn in the following order: top 1 / bottom 1 / top 1 / bottom 4 / top 1 / bottom 1 / top 1 / bottom 2.

4. 4. The forming fabric of claim 1, wherein each of the bonding warp yarns from the first set and the second set includes a segment in which each of the bonding warp yarns is interwoven with the top weft yarn in the following order: top 1 / bottom 1 / top 1 / bottom 5 / top 1 / bottom 1 / top 1 / bottom 1.

5. 5. The forming fabric of claim 1, wherein a repeat unit of the upper fabric layer includes four bonding warps from the first set, four bonding warps from the second set, four spring warps, and twelve upper wefts, and a repeat unit of the lower fabric layer includes four lower warps, eight bonding warps, and eight lower wefts.

6. The forming fabric of any one of claims 1 to 5, wherein the arrangement of the dual knuckles along the bottom fabric layer follows a zigzag pattern.

7. 7. The forming fabric of claim 6, wherein the zigzag pattern includes a first set of double knuckles formed on a first diagonal and a second set of double knuckles formed on a second diagonal, each set of double knuckles including four double knuckles, and the second diagonal of double knuckles is offset from the first diagonal of double knuckles.

8. 8. The forming fabric of claim 7, wherein each diagonal includes four double knuckles, each double knuckle being formed by bottom warp yarns and binding warp yarns from the first set or the second set.

9. the upper fabric layer includes a series of repeat units of weft paths including at least one first weft path, at least one second weft path, and at least one third weft path; (a) the first weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the following order: upper 3 / lower 1 / upper 2 / lower 1 / upper 2 / lower 1 / upper 1 / lower 1; (b) the second weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the following order: Upper 3 / Lower 1 / Upper 2 / Lower 1 / Upper 1 / Lower 1 / Upper 2 / Lower 1; and (c) the third weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the order of upper 3 / lower 1 / upper 1 / lower 1 / upper 2 / lower 1 / upper 2 / lower 1. The shaped fabric of any one of claims 1 to 8.

10. 10. The forming fabric of claim 9, wherein the weft thread repeat unit includes weft thread segments arranged as follows: the first weft thread, the second weft thread, the first weft thread, the third weft thread, the second weft thread, and the third weft thread.

11. 11. The forming fabric of claim 9 or 10, wherein the weft-path repeat unit forms a top fabric layer without visible diagonal lines.

12. 12. The forming fabric of claim 9, wherein the weft-path repeat unit forms a plain weave zone in the top fabric layer in a paisley pattern configuration.

13. 13. The forming fabric of any one of claims 9 to 12, wherein successive weft-path repeat units form a mirror symmetrical paisley pattern shaped plain weave zone in the top fabric layer.

14. 14. The forming fabric of claim 12 or 13, wherein the paisley patterned plain weave zone formed in the top fabric layer is aligned between double knuckle zigzag lines formed in the bottom fabric layer.

15. 14. The forming fabric of claim 9, wherein the segments of the first weft path, the second weft path, and the third weft path passing over three warp yarns of the upper fabric layer are aligned at the center and between two double knuckles in the warp direction formed in the lower fabric layer.

16. The formed fabric according to any one of claims 7 to 15, wherein the bottom weft yarn on the right side of a first double knuckle of a diagonal line has an asymmetric shape that forms a wider contact area than the same bottom weft yarn on the left side of the first double knuckle of an adjacent diagonal line, and the bottom weft yarn on the left side of a fourth double knuckle of the diagonal line has an asymmetric shape that forms a wider contact area than the same bottom weft yarn on the right side of the fourth double knuckle of the adjacent diagonal line.

17. 17. The forming fabric of claim 16, wherein the bottom weft yarns on the left and right of the diagonal second and third double knuckles have symmetrical shapes with substantially equal contact areas.

18. 18. The formed fabric of any one of claims 1 to 17, wherein the binding warp yarns and the spring warp yarns from the first and second sets are interwoven with the top weft yarns to relatively form a plain weave pattern in a determined zone such that (a) the first set of binding warp yarns pass over only odd-numbered top weft yarns, (b) the second set of binding warp yarns pass over only even-numbered top weft yarns, (c) a first binding warp yarn of the pair is offset from a second binding warp yarn of the pair by at least three top weft yarns to form an overlap in the warp path of the pair of binding warp yarns, and (d) each of the spring warp yarns passes over an even and an odd-numbered top weft yarn.

19. 19. The forming fabric of any one of claims 1 to 18, wherein the forming fabric has a weft ratio of three top wefts to two bottom wefts (3:2).

20. 1. A forming fabric comprising a series of repeat units, each of the repeat units comprising: a bonding warp set including a first set of bonding warp yarns and a second set of bonding warp yarns, wherein the bonding warp yarns from the first set are paired with the bonding warp yarns from the second set; a set of spring warp yarns, each of the spring warp yarns having a spring elasticity and between the first pair of binding warp yarns and the second pair of binding warp yarns; a set of upper weft yarns, the upper weft yarns interwoven with the binding warp yarns and the spring warp yarns to form an upper fabric layer, the spring warp yarns interwoven only with the upper weft yarns, and a first pair of binding warp yarns are offset in the warp direction relative to a second pair of binding warp yarns in an alternating manner by at least four upper wefts in the weft direction; Set the lower weft and a set of lower warp yarns, the lower warp yarns interwoven with the lower weft yarns to form a lower fabric layer; Including, the bonding warp yarns and the bottom warp yarns from the first and second sets are interwoven with the bottom weft yarns such that (a) each of the bottom warp yarns forms a plurality of knuckles along the bottom fabric layer, (b) each of the bonding warp yarns from the first set is interwoven with the bottom warp yarns under the bottom weft yarns to form double knuckles, and (c) each of the bonding warp yarns from the second set is interwoven with the bottom warp yarns under the bottom weft yarns to form double knuckles.

21. 21. The forming fabric of claim 20, wherein the forming fabric has a weft ratio of two weft yarns to one bottom weft yarn (2:1).

22. 22. The forming fabric of claim 20 or 21, wherein two lower weft yarns are between a first double knuckle formed by the lower warp yarn and a first bonding warp yarn and a second double knuckle formed by the same lower warp yarn and a second bonding warp yarn.

23. The shaped fabric of any one of claims 20 to 22, wherein each of the spring warp yarns includes a segment in which the spring warp yarn is interwoven with the upper weft yarn in the following order: top 1 / bottom 2 / top 1 / bottom 1 / top 1 / bottom 1 / top 1 / bottom 4 / top 1 / bottom 1 / top 1 / bottom 1.

24. 24. The forming fabric of any one of claims 19 to 23, wherein each of the bonding warp yarns from the first set and the second set includes a segment in which each bonding warp yarn is interwoven with the top weft yarn in the following order: top 1 / bottom 1 / top 1 / bottom 1 / top 1 / bottom 7 / top 1 / bottom 1 / top 1 / bottom 1.

25. the upper fabric layer includes a series of repeat units of weft paths including at least one first weft path, at least one second weft path, and at least one third weft path; (a) the first weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the following order: upper 3 / lower 1 / upper 2 / lower 1 / upper 2 / lower 1 / upper 1 / lower 1; (b) the second weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the following order: Upper 3 / Lower 1 / Upper 2 / Lower 1 / Upper 1 / Lower 1 / Upper 2 / Lower 1; and (c) the third weft path includes a segment in which an upper weft is interwoven with the binding warp and the spring warp in the following order: upper 3 / lower 1 / upper 1 / lower 1 / upper 2 / lower 1 / upper 2 / lower 1. The shaped fabric of any one of claims 19 to 24.

26. 26. The forming fabric of claim 25, wherein the weft thread repeat unit includes weft thread segments arranged as follows: the first weft thread, the third weft thread, the second weft thread, the second weft thread.

27. 27. The forming fabric of claim 25 or 26, wherein the weft yarn-path repeat units form a plain weave zone in the top fabric layer in a paisley pattern configuration.

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