Papermaking fabric with edge sewn with fusible thread

Abstract

A method of producing an industrial fabric includes the steps of: (a) providing a woven fabric having interlaced MD and CMD yarns; (b) cutting excess edges from the CMD edges of the woven fabric to create edge portions on the fabric; (c) sewing a fusible thread into at least one of the edge portions; and (d) transforming the fusible thread so that the fusible thread mechanically interlocks with the MD yarns and the CMD yarns of the at least one edge portion.

Description

PAPERMAKING FABRIC WITH EDGE SEWN WITH FUSIBLE THREADStatement of Priority

[0001] The present application claims priority from and the benefit of U.S. Provisional Patent Application No. 63 / 676,470, filed July 29, 2024, the disclosure of which is hereby incorporated herein by reference in full.Field of the Invention

[0002] The present application relates generally to industrial fabrics, and more particularly to fabrics employed in papermaking.Background of the Invention

[0003] In the conventional fourdrinier papermaking process, a water slurry, or suspension, of cellulosic fibers (known as the paper "stock") is fed onto the top of the upper run of an endless belt of woven wire and / or synthetic material that travels between two or more rolls. The belt, often referred to as a "forming fabric," provides a papermaking surface on the upper surface of its upper run that operates as a filter to separate the cellulosic fibers of the paper stock from the aqueous medium, thereby forming a wet paper web. The aqueous medium drains through mesh openings of the forming fabric, known as drainage holes, by gravity or vacuum located on the lower surface of the upper run ( / .e., the "machine side") of the fabric.

[0004] After leaving the forming section, the paper web is transferred to a press section of the paper machine, where it is passed through the nips of one or more pairs of pressure rolls covered with another fabric, typically referred to as a "press felt." Pressure from the rolls removes additional moisture from the web; the moisture removal is enhanced by the presence of a "batt" layer of the press felt. The paper is then transferred to a dryer section (which utilizes a dryer fabric) for further moisture removal. After drying, the paper is ready for secondary processing and packaging.

[0005] As used herein, the terms machine direction ("MD") and cross-machine direction ("CMD") refer, respectively, to a direction aligned with the direction of travel of the papermakers' fabric on the papermaking machine, and a direction parallel to the fabric surface and traverse to the direction of travel. Likewise, directional references to the vertical relationship of the yarns in the fabric (e.g., above, below, top, bottom, beneath, etc.) assume that the papermaking surface of the fabric is the top of the fabric and the machine side surface of the fabric is the bottom of the fabric.

[0006] Typically, papermaker's fabrics are manufactured as endless belts by one of two basic weaving techniques. The term "endless belt" as used herein refers to belts made by either method. In the first of these techniques, fabrics are flat woven by a flat weaving process, with their ends being joined to form an endless belt by any one of a number of well-known joining methods, such as dismantling and reweaving the ends together (commonly known as splicing), or sewing on a pin-seamable flap or a special foldback on each end, then reweaving these into pin-seamable loops. In the second basic weaving technique, fabrics are woven directly in the form of a continuous belt with an endless weaving process.

[0007] During the final processing of the fabric, the fabric is precisely cut under tension to a desired width (typically determined by the paper machine that will ultimatelybe clothed with the fabric). When cutting, care is taken to achieve a straight edge without width variations during the process. A "warp straight" cut creates an "open" weave at the outermost thread of the fabric, which is typically closed again through a thermal process. Fabric edges are cut straight with an ultrasonic unit and simultaneously welded; special cutting wheels (with adapted cutting angle) are used for this purpose.

[0008] After straight cutting, areas of the edges (e.g., 5 / 10 / 15mm from the cloth edge) are encapsulated with polymeric material such as polyurethane or silicone for mechanical protection. The finished product is illustrated in FIGS. 1A and IB, which show a fabric 100 with a coating 110 applied thereto. The polymeric materials are liquefied using a melting apparatus and applied under pressure onto / through the fabric edge (there are various nozzle attachments for application, depending on the fabric characteristics). Unfortunately, in practice, it is often observed that threads are pulled out or edges are heavily frayed. This can negatively affect paper production.

[0009] In view of the foregoing, it may be desirable to provide an improved technique for enhancing the edges of a papermaking fabric.Summary of the Invention

[0010] As a first aspect, embodiments of the invention are directed to woven industrial fabric, such as a papermaking fabric. The woven fabric comprises: a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction; and a fusible thread joined into at least one of the edge portions. The fusible thread is transformed to interlock with the MD and CMD yarns of the at least one edge portion.

[0011] As a second aspect, embodiments of the invention are directed to a method of producing an industrial fabric. The method comprises the steps of:(a) providing a woven fabric having interlaced MD and CMD yarns;(b) cutting excess edges from the CMD edges of the woven fabric to create edge portions on the fabric;(c) joining a fusible thread into at least one of the edge portions; and(d) transforming the fusible thread so that the fusible thread mechanically interlocks with the MD yarns and the CMD yarns of the at least one edge portion.

[0012] As a third aspect, embodiments of the invention are directed to a woven industrial fabric comprising: a woven body comprising interlaced MD and CMD yarns in a first weaving pattern, the woven body having edge portions on opposite sides in the CMD direction; and a fusible thread sewn into at least one of the edge portions in a second pattern that differs from the first weaving pattern.

[0013] As a fourth aspect, embodiments of the invention are directed to a method of making paper comprising:(a) determining at least one property of a papermaking fabric on a paper machine, at least one property of the paper machine, or at least one property of the paper, wherein the papermaking fabric comprises a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction, and wherein the papermaking fabric further comprises a fusible thread interlocking with the MD and CMD yarns of at least one edge portion; and(b) regulating at least one property of the papermaking fabric, at least one operation behavior of the fabric, or replacing the papermaking fabric.

[0014] As a fifth aspect, embodiments of the invention are directed to a woven industrial fabric comprising: a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction, at least some of the MD yarns and / or CMD yarns being formed of a first material; and a coating applied to at least one of the edge portions, the coating being formed of the first material.Brief Description of the Figures

[0015] FIG. 1A is an enlarged partial top view of a conventional edge-sealed fabric.

[0016] FIG. IB is a partial section view of the edge of the fabric of FIG. 1.

[0017] FIG. 2 is a partial top perspective view of two fabrics with fusible threads sewn into their edge portions according to embodiments of the invention.

[0018] FIG. 3 is a flow chart illustrating operations for creating a fabric of FIG. 2.Detailed Description of the Invention

[0019] The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as 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.

[0020] The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown.

[0021] As used herein, the terms machine direction ("MD") and cross-machine direction ("CMD") refer, respectively, to a direction aligned with the direction of travel of the forming fabric on the papermaking machine, and a direction parallel to the fabric surface and traverse to the direction of travel. Likewise, directional references to the vertical relationship of the yarns in the fabric (e.g., above, below, top, bottom, beneath, etc.) assume that the paper making surface of the fabric is the top of the fabric and the machine side surface of the fabric is the bottom of the fabric.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude 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.

[0024] In addition, spatially relative terms, such as "under", "below", "lower", "over","upper", "top", "middle", "bottom" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) asillustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0025] Well-known functions or constructions may not be described in detail for brevity and / or clarity.

[0026] As discussed above, edge portions of papermaking fabrics can be susceptible to fraying and other non-uniformities. There are a number of reasons that non-uniform edges are detrimental to fabric performance and may benefit from coating as discussed above. These include:• The longitudinal fabric edges of paper machine clothing and fabric webs are exposed to increased abrasion compared to the fabric body. Edge coating counteracts this wear.• Mechanical sensors or other paper machine devices are often attached to the sides of paper machines; these measure and regulating diverse properties of the fabric as well as the running behavior of a fabric. These devices can cause mechanical stress / friction and abrasion in the fabric edge area. Edge sealing / reinforcement counteracts or reduces these effects.• If measurements and regulation are not correct, the fabric may fail in the paper machine. Edge sealing then provides greater stability and wear resistance.• Due to stress and abrasion in the fabric edge area, single fabric threads or parts thereof it may be inadvertently removed, thereby negatively affecting the manufacturing process.• Fringed fabric edges in the edge area can lead to paper- and / or water- dragging and spraying, negatively impacting the paper web manufacturing process.• Many paper machines are twin-wire formers. Often there are small differences of the fabric width between the top wire and the bottom wire. If the fabric edges are not protected by sealing, they can cut or otherwise destroy themselves, wearing significantly faster in the edge areas.• Fringed edges may also affect to lateral tearing of the fabric, which can in turn cause the whole fabric to tear.

[0027] Although these are some of the benefits that can be achieved by coating the edges of the fabric as described, there are also potential drawbacks. In addition to some materials used in the coatings producing potential health concerns, the application of the material itself may not be reproducibly uniform, additional equipment is required, waste can be created, and labor and time costs can be significant.

[0028] These and other issues may be addressed with embodiments of the present invention. Many of the benefits provided by a sealed edge on a papermaking fabric may be achieved by including in the fabric a fusible thread or yarn sewn into the edge portion of the fabric (as used herein, an "edge" portion of a fabric is a relatively narrow strip extending from the edge of the fabric toward the center of the fabric. The remainingextent of the fabric is referred to herein as the "body" of the fabric). The fusible thread may be melted, and therefore mechanically integrated, into the edge portions of the fabric after sewing. The inclusion of a fusible thread can form an inseparable and defined interconnection with the fabric to reinforce the stressed fabric edge.

[0029] The fusible thread may be selected based on the structure of the fabric itself, which can vary greatly in weave pattern, yarn size, mesh size, and the like. In some embodiments, the fusible thread may be formed of polyethylene terephthalate (PET), polyamide (PA) (e.g., Nylon), and other thermoplastic yarns. The fusible thread may be monofilament or multifilament. In some instances, the material for the fusible thread is formed of the same material as the fabric (e.g., a PA fusible thread may be employed with a PA fabric).

[0030] The size of the fusible thread may also vary depending on the structure of the fabric. For example, for papermaking forming fabrics, a thread size of 150-800 dtex may be appropriate. For other fabrics (e.g., for coarse industrial fabrics such as dryer fabrics, transport fabrics, pulp dewatering fabrics and the like), the fusible thread may have a size of between about 800 to 10,000 dtex. In some embodiments the fusible thread may be a band or strip. Typically, the size of the fusible thread is selected so that the application height of the thread is no greater than 1 mm.

[0031] Sewing of the fusible thread into the edge portions of the fabric may be done with different stitches or patterns. As examples, as shown in FIG. 2, an overlock stitch 10 may be sewn onto the edge portion 12 of a fabric 14, or a zig-zag stitch 20 may be sewn onto the edge portion 22 of a fabric 24. A stitch pattern should be selected that reduces or eliminates fraying of the fabric edge. In some embodiments, the stitches may extend between about 2.5 and 20 mm into the fabric (i.e., they may extend between about 2.5 and 20 mm from the edge of the fabric toward the center of the fabric).

[0032] The fusible thread may be sewn into the fabric with a sewing machine (e.g., a sewing machine with 1-4 needles), and may be inserted from either above or below the fabric. Different sizes of needles may be employed for the sewing process. In instances in which multiple needles are used, different sizes and / or types of fusible threads may be used in the same fabric.

[0033] After the fusible thread is sewn into the edges of the fabric, the fusible thread is softened, at least partially melted, or otherwise transformed to enable the stitches of the fusible thread to mechanically "lock" into the yarns of the fabric. Softening / melting / transformation of the fusible thread may be achieved via heat, UV light, chemical treatment, plasma treatment, laser, or the like. In some instances, heat may be applied with rolls or rails that engage the edge of the fabric. In such embodiments, the rolls or rails may also help to provide smoothness to the edge surface, and / or may assist with controlling thickness of the fabric.

[0034] In some embodiments, it may be desirable to perform the steps of cutting the edge from the fabric and sewing the fusible thread into the fabric in immediate succession; i.e., an arrangement may be created in which the cutting and sewing stations may be adjacent to each other, such thatthe freshly cut fabric is immediately presented for sewing of the fusible thread. Further, an arrangement may be created in which the fusible thread is immediately melted after being sewn into the edge portions of the fabric.

[0035] The basic steps of the process are illustrated in FIG. 3. First, a strip of fabric is cut from each edge of a woven fabric (Box 210). A fusible thread as discussed above is sewn or otherwise joined into the remaining edge portion of the fabric (Box 220). Transformation (e.g., via melting) of the fusible thread is then induced (via heat, UV light, etc. as listed above) to mechanically attach the fusible thread to the edge portion of the fabric (Box 230). Optionally, the melted fusible thread may be further processed (e.g., viathe application of pressure via a roll or a rail) to achieve smoothness and uniformity (Box 240). As discussed above, in some embodiments steps 230 and 240 may be performed simultaneously (e.g., a heated roll may be used to both melt the fusible thread and smooth the resulting edge portion).

[0036] It should be understood that producing fabrics with fusible threads sewn into their edges can provide many of the benefits achieved for fabrics that have "coated" edge portions. However, these benefits can be achieved without many of the drawbacks (cost, time, labor, safety, non-uniformity) that can plague coated edge portions. In addition, if the fusible thread is formed of the same material as the fabric (e.g., if a PA fusible thread is employed with a fabric woven of PA), the entire fabric can be recycled, rather than having to first separate the coated edge portions from the rest of the fabric.

[0037] It should also be understood that, although papermaking fabrics are discussed primarily above in connection with sewing of fusible threads into cut edges of fabrics, other industrial fabrics, such as dryer fabrics, transport fabrics, pulp dewatering fabrics, and the like, may also benefit from the concepts discussed herein.

[0038] Further, it will be understood that fabrics as described above may be utilized in processes in which a paper machine or paper made thereby may be monitored during operation. Thus, embodiment of the invention may include a method of making paper comprising as an initial step determining at least one property of a papermaking fabric on a paper machine, at least one property of the paper machine, or at least one property of the paper. The papermaking fabric used in the papermaking machine comprises a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction, and further comprises a fusible thread interlocking with the MD and CMD yarns of at least one edge portion. The method further includes the step of regulating at least one property of the papermaking fabric, at least oneoperation behavior of the fabric, or replacing the papermaking fabric based on the determination of the property in the initial step. Potential properties of the fabric include caliper, tension, wear, and the like. Potential properties of the paper machine include speed, pressure, temperature, moisture, wear, and the like. Potential properties of the paper include travel speed, temperature, thickness, moisture, marking and the like. Other properties may also be determined and regulated.

[0039] Moreover, a fabric according to embodiments of the invention may include a complete or partial coating on edge portions thereof that is formed of a material that is also employed for at least some of the MD and / or CMD yarns of the fabtic. For example, a polyamide (Nylon) coating may be applied to a fabric that has at least some polyamide yarns.

[0040] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such 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 to be included therein.

Claims

What is Claimed is:

1. A woven industrial fabric, comprising: a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction; and a fusible thread joined into at least one of the edge portions; wherein the fusible thread is transformed to interlock with the MD and CMD yarns of the at least one edge portion.

2. The fabric defined in Claim 1, wherein the fusible thread is formed of a first material, and wherein one of the MD and CMD yarns is formed of the first material.

3. The fabric defined in Claim 1 or Claim 2, wherein the fusible thread is sewn into the at least one edge portion.

4. The fabric defined in Claim 3, wherein the fusible thread is sewn into the at least one edge portion in a zig-zag stitching pattern or an overlooking stitching pattern.

5. The fabric defined in any of Claims 1-4, wherein the fusible thread is formed of polyamide or polyethylene terephthalate.

6. The fabric defined in any of Claims 1-5, installed in the forming section of a papermaking machine.

7. The fabric defined in any of Claims 1-6, wherein the fusible thread has a size between about 150-800 dtex.

8. The fabric defined in any of Claims 1-7, wherein the fusible thread extends inwardly between about 2.5 and 20 mm from an edge of the at least one edge portion.

9. The fabric defined in any of Claims 1-8, wherein the fusible thread is transformed to interlock with the MD and CMD yarns via melting.

10. A method of produced an industrial fabric, comprising the steps of:(a) providing a woven fabric having interlaced MD and CMD yarns;(b) cutting excess edges from the CMD edges of the woven fabric to create edge portions on the fabric;(c) joining a fusible thread into at least one of the edge portions; and(d) transforming the fusible thread so that the fusible thread mechanically interlocks with the MD yarns and the CMD yarns of the at least one edge portion.

11. The method defined in Claim 10, wherein step (d) comprises heating the fusible thread.

12. The method defined in Claim 10 or Claim 11, further comprising the step of pressing the transformed fusible thread to increase smoothness.

13. The method defined in Claim 10, wherein the fusible thread is formed of a first material, and wherein one of the MD and CMD yarns is formed of the first material.

14. The method defined in Claim 10, wherein in step (c) the fusible thread is sewn into the at least one edge portion.

15. The method defined in Claim 10, wherein in step (c) the fusible thread is sewn into the at least one edge portion in a zig-zag stitching pattern or a overlocking stitching pattern.

16. The method defined in Claim 10, wherein the fusible thread is formed of polyamide or polyethylene terephthalate.

17. The method defined in Claim 10, wherein the fusible thread has a size between about 150-800 dtex.

18. The method defined in Claim 10, wherein step (c) comprises sewing the fusible thread so that the fusible thread extends inwardly between about 2.5 and 20 mm from an edge of the at least one edge portion.

19. A woven industrial fabric, comprising: a woven body comprising interlaced MD and CMD yarns in a first weaving pattern, the woven body having edge portions on opposite sides in the CMD direction; and a fusible thread sewn into at least one of the edge portions in a second pattern that differs from the first weaving pattern.

20. A method of making paper, the method comprising:(a) determining at least one property of a papermaking fabric on a paper machine, at least one property of the paper machine, or at least one property of the paper, wherein the papermaking fabric comprises a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction, and wherein the papermaking fabric further comprises a fusible thread interlocking with the MD and CMD yarns of at least one edge portion; and(b) regulating at least one property of the papermaking fabric, at least one operation behavior of the fabric, or replacing the papermaking fabric.

21. A woven industrial fabric, comprising: a woven body comprising interlaced MD and CMD yarns, the woven body having edge portions on opposite sides in the CMD direction, at least some of the MD yarns and / or CMD yarns being formed of a first material; and a coating applied to at least one of the edge portions, the coating being formed of the first material.

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