MXPA00006700A - Multi-axial press fabric - Google Patents

Abstract

A multi-axial press fabric includes a base fabric and several layers of staple fiber material attached to the base fabric by needling. The base fabric has at least one layer assembled by spirally winding a woven fabric strip. The base fabric takes the form of an endless loop. The yarns of the woven fabric strip accordingly lie in directions different from the machine- and cross-machine directions of the base fabric, giving the base fabric multi-axial characteristics. Individual fibers in the several layers of staple fiber material attached to the base fabric are predominantly oriented at oblique angles relative to the machine direction of the press fabric. More specifically, they form a crisscrossed angular web.

Description

MULTIAXIAL PRESSURE FABRIC WITH ANGULAR NETWORK Background of the Invention 1. Field of the Invention The present invention relates to papermaking techniques. More specifically, the present invention relates to press fabrics for the press section of a paper machine. 2. Description of the Prior Art During the papermaking process, a network of cellulosic fibers is formed by depositing a fiber suspension, i.e., an aqueous dispersion of cellulose fibers, on a moving forming fabric in the forming section of a cellulose fiber. a machine to make paper. A large amount of water is drained from the suspension through the forming fabric, leaving the network of cellulosic fibers on the surface of the forming fabric. The newly formed network of cellulosic fibers comes from the forming section to a pressing section, which includes a series of clamping points of a press. The network of cellulosic fibers passes through the fastening points of the press supported by a press fabric, or, as is often the case, between two such press fabrics. At the points of attachment of the press, the network of cellulosic fibers is subjected to compressive forces, which squeeze water from it, and which adhere the cellulosic fibers in the network together to transform the network of cellulosic fibers into a paper sheet. The water is accepted by the fabric or press fabrics and, ideally, does not return to the sheet of paper. The sheet of paper finally proceeds to a drying section, which includes at least a series of rotating drying drums or cylinders, which are internally heated by steam. The newly formed paper sheet is directed in a serpentine path sequentially around each of a series of drums by means of a drying cloth, which keeps the sheet of paper very close to the surfaces of the drums. The hot drums reduce the water content of the paper sheet to a desirable level through evaporation. It should be appreciated that the forming, pressing and drying fabrics take the form of endless bands on the papermaking machine and function in the form of conveyors. It should also be noted that papermaking is a continuous process, which proceeds at considerable speeds. That is, the fiber suspension is continuously deposited on the forming fabric in the forming section, while a freshly made sheet of paper is continuously rolled onto rolls after it leaves the drying section. The present invention relates specifically to the press fabrics used in the pressing section. Press fabrics play a critical role during the papermaking process. One of its functions, as explained above, is to support and transport the paper product that is being manufactured through the fastening points of the press. The press fabrics also take part in the finishing of the surface of the paper sheet. That is, the press fabrics are designed so that they have smooth surfaces and uniformly elastic structures, so that, during their passage through the clamping points of the press, they impart a smooth surface, free of marks to the paper. Perhaps more importantly, press fabrics accept large quantities of water extracted from the wet paper at the press attachment points. To perform this function, there must literally be some place, commonly known as empty volume, within the press fabric where the water can go, and the fabric must maintain adequate water permeability throughout its useful life. Finally, the press fabrics must be able to prevent the accepted water of the wet paper from returning and rewetting the paper that comes out above the clamping points of the press. Contemporary press fabrics are produced in a wide variety of styles designed to meet the requirements of the paper machines on which they are installed., for the grades of paper that are manufactured. In general, they comprise a woven base fabric in which a block of fibrous material of fine, non-woven fibrous material has been woven. The base fabrics can be woven from single filament yarns, a single folded filament, multiple filaments or folded multiple filaments, and can be single layer, multilayer, or laminated. The yarns are typically extruded from any synthetic polymeric resins, such as polyamide and polyester resins, used for this purpose by those skilled in the coating techniques in paper machines. The woven base fabrics themselves take many different forms. For example, they may be of endless fabric, or flat fabric and subsequently converted to an endless shape with a woven seam. Alternatively, they can be produced by a process commonly known as modified endless fabric, wherein the edges across the width of the base fabric are provided with sewing rings that use the yarns in the machine direction (MD) thereof. . In this process, the MD yarns are continuously woven from back to front and between the edges across the width of the fabric, at each edge returning back and forming a seam ring. A base fabric produced in this way is placed in an endless form during its installation on a paper machine, and for this reason it is known as fabric that can be sewn on the machine. end, the two edges in the width are put together, the rings of the seam on the two edges intertwine with each other, and a pin or sewing needle is directed through the passage formed by the interlocked seam rings. Woven base fabrics can be laminated by placing a base fabric within the endless band formed by another, and by sewing a block of fibrous fiber material cut through both base fabrics to join them together One or both of the woven base fabrics can be In any case, the woven base fabrics are in the form of endless bands, or they can be sewn in such shapes, having a specific length, measured longitudinally around them, and a specific width, measured transversely across it. Because configurations of papermaking machines vary widely, manufacturers of coatings of papermaking machines are required to produce press fabrics, and other coatings of papermaking machines, with the dimensions required to conform to particular positions in papermaking. the papermaking machines of their customers. Needless to say, this requirement makes it difficult to carry out the manufacturing process, since each press fabric must typically be made to order. In response to this need to produce press fabrics in a variety of lengths and widths more quickly and efficiently, in recent years press fabrics have been produced using a spiral technique described in U.S. Patent No. 5,360,656, commonly issued to Rexfelt et al. ., the teachings of which are incorporated here as a reference. U.S. Patent No. 5,360,656 shows a press fabric comprising a base fabric having one or more layers of cut fiber material sewn thereon. The base fabric comprises at least one layer composed of a spirally wound woven fabric strip, having a width that is smaller than the width of the base fabric. The base fabric has no end in the longitudinal or machine direction. The longitudinal strands of the spirally wound strip form an angle with the longitudinal direction of the press fabric. The woven fabric strip may be of flat fabric on a fabric which is narrower than those typically used in the production of coatings of papermaking machines. The base fabric comprises a plurality of spirally wound and joined turns of the relatively narrow woven fabric strip. The strip of fabric is woven of longitudinal (warp) and transverse (weft) threads. The adjacent turns of the spirally wound fabric strip can be brought into contact with each other, and the helical continuous seam thus produced, can be closed by sewing, knitting, melting or welding. Alternatively, the adjacent longitudinal side edge portions of the adjacent spiral turns can be arranged superimposed, as long as the edges have a reduced thickness, so as not to cause an increase in thickness in the area of the overlap. In addition, the separation between the longitudinal threads can be increased at the edges of the strip, so that, when the attached spiral turns are arranged superimposed, there can be a separation without change between the longitudinal threads in the area of the overlap. In any case, a woven base fabric, which takes the form of an endless vessel or band and which has an internal surface, a longitudinal direction (of the machine), and a transverse direction (transverse to the machine), is the result . The side edges of the woven base fabric are then cut to make them parallel to their longitudinal (machine) direction. The angle between the machine direction of the woven base fabric and the helically continuous seam can be relatively small, i.e., typically less than 10 °. In the same sense, the longitudinal (warp) threads of the woven fabric strip form the same relatively small angle with the longitudinal (machine) direction of the woven base fabric. Similarly, the transverse (weft) threads of the woven fabric strip, which are perpendicular to the longitudinal (warp) yarns, form the same relatively small angle with the transverse direction (transverse to the machine) of the base fabric woven. In summary, neither the longitudinal (warp) nor the cross (weft) threads of the woven fabric strip align with the longitudinal (machine) or transverse (machine transverse) directions of the woven base fabric. In the method shown in U.S. Patent No. 5,360,656, the woven fabric strip is wound around the parallel rollers to assemble the woven base fabric. It should be recognized that endless base fabrics can be provided in a variety of widths and lengths by spirally winding a relatively narrow piece of woven fabric strip around the parallel rolls, the length of a particular endless base fabric being determined by the length of each spiral spin of the woven fabric strip, and the width being determined by the number of spiral turns of the woven back strip. The previous need to weave full base fabrics of specific lengths and widths can thus be avoided. Instead, a loom as narrow as 20 inches (0.5 meters) could be used to produce a strip of woven fabric, but, for practical reasons, a conventional textile loom with a width of 40 to 60 inches may be preferred (1.0 to 1.5 meters). U.S. Patent No. 5,360,656 also shows a press fabric comprising a base fabric having two layers, each composed of a spirally wound strip of woven fabric. Both layers take the form of a ship endless bands, one being inside the loop or endless band formed by the other. Preferably, the spirally wound strip of woven fabric in one layer is wound spirally in a direction opposite that of the strip of woven fabric in the other layer. That is, more specifically, that the strip spirally wound in one layer defines a right spiral, while the other layer defines a left spiral. In such a two-layer laminated base fabric, the longitudinal (warp) yarns of the woven fabric strip in each of the two layers form relatively small angles with the longitudinal (machine) direction of the woven base fabric, and longitudinal (warp) threads of the fabric strip in one layer make an angle with the longitudinal (warp) threads of the strip of woven fabric in the other layer. In a similar way, the transverse (weft) yarns of the strip of woven fabric in each of the two layers form relatively small angles with the transverse direction (transverse to the machine) of the woven base fabric, and the transverse (weft) yarns of the strip of fabric woven in one layer forms an angle with the transverse (weft) threads of the strip of woven fabric in the other layer. In summary, neither the longitudinal (warp) nor the transverse (weft) threads of the strip of woven fabric in any layer align with the longitudinal (machine), transverse (transverse to machine) directions of the base fabric . Furthermore, neither the longitudinal (warp) and transverse (weft) threads of the strip of woven fabric in any one layer align with those of another. Accordingly, the base fabrics shown in U.S. Patent No. 5,360,656 have no defined cross machine machine direction yarns. Instead, the yarn systems are in directions at oblique angles to the machine and transverse directions to the machine. A press fabric having such a base fabric can be referred to as a multi-axial press fabric. While the standard press fabrics of the prior art have three axes: one in the machine direction (MD), one in the cross machine direction (CD), and one in the Z direction, which is through the thickness of the fabric, a multi-axial press fabric not only has those three axes, but also has at least two axes more defined by the directions of the yarn systems in its layer or layers wound spirally. In addition, there are multiple flow paths in the Z direction of the multi-axial press fabric. As a result, a multi-axial press fabric has at least five axes. Due to its multi-axial structure, a multiaxial pressing fabric having more than one layer, exhibits superior resistance to nesting and / or collapse in response to compression at a pressing point during the papermaking process as compared to a fabric base that has layers whose thread systems are parallel to each other. The present invention is an improved multiaxial pressing fabric having a base fabric of the above type and a plurality of layers of cut fiber material sewn thereon. The fibers constituting the layers of predominantly cut fiber material are found in directions different from the lengths to the longitudinal (machine) and transverse (machine-transversal) directions of the multiaxial press fabric, and specifically at oblique angles at relation to the longitudinal direction, thus providing a pressing cloth whose components can be considered all multiaxial.

Brief Description of the Invention In its broadest form, the multiaxial pressing fabric of the present invention for the pressing section of a papermaking machine comprises a base fabric having at least one layer formed by spirally winding a strip of fabric. The strip of fabric can be woven of longitudinal threads and transverse threads. Alternatively, the fabric strip can be a non-woven mesh strip of the variety described in U.S. Pat. Commonly assigned No. 4,427,734 to Johnson, the teachings of which are incorporated herein by reference. In any case, the fabric strip has a first side edge and a second side edge, and is wound spirally in a plurality of contiguous turns, where the first side edge in one turn of the fabric strip comes in contact with the second edge. side of an adjacent turn of it. Therefore, a helically continuous seam is formed which separates the adjacent turns of the fabric strip. The helically continuous seam is closed by contacting the first and second side edges of the fabric strip together. In this way, a base fabric is provided in the form of an endless loop or band having a machine direction, a cross machine direction, an inner surface and an outer surface. The base fabric may comprise one or more additional layers formed by spirally winding strips of fabric, which may be woven from longitudinal threads and transverse threads, or which, alternatively, may be non-woven mesh fabrics of the variety identified above. The additional fabric strips also have first side edges and second side edges, and are spirally wound in a plurality of contiguous turns where the first side edge in one turn of each additional fabric strip comes in contact with the second side edge of a turn adjacent to it. Therefore, a helically continuous seams are formed which separate the adjacent turns of the additional fabric strip. The helically continuous seams are closed by contacting the first and second side edges of each additional fabric strip together. In this manner, one or more additional layers are provided in the form of an endless loop or band having a machine direction, a machine transverse direction, an inner surface and an outer surface. Preferably, at least some of the additional fabric strips are wound spirally in a direction opposite to that in which the first strip of fabric was spirally wound. The endless bands or loops formed by the additional layers are placed with or without the loop or band formed by the first layer. A plurality of layers of cut fiber material is attached to one or both of the inner and outer surfaces of the base fabric. At the same time, where the base fabric includes more than one layer, the layers are joined to each other by individual fibers of the cut fiber material sewn therethrough. The fibers constituting the layers of cut fiber material are oriented predominantly at oblique angles in relation to the machine direction of the base fabric, and are considered to constitute an angular network. That is, more specifically, that the fibers in each of the plurality of layers of cut fiber material are predominantly oriented in a substantially parallel manner with each other in a direction that forms an oblique angle with respect to the machine direction. In addition, the oblique angle is the same for each of the plurality of layers. Finally, the direction for each of the plurality of layers has an opposite direction to that of any immediately underlying or superimposed layer, to produce a cross-linked angular network. The present invention will now be described in greater detail with frequent reference to the Figures identified below.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic top plan view illustrating a method for manufacturing one of the layers of the base fabric of the multi-axial press fabric of the present invention; Figure 2 is a top plan view of the finished layer of the base fabric; Figure 3 is a cross-sectional view taken as indicated by line 3-3 in Figure i; Figure 4 is a top plan view of a laminated, two-ply base fabric for the multi-axial press fabric of the present invention; Figure 5 is a schematic, amplified view of a portion of the outer surface of the laminated two-ply base fabric; Figure 6 is a perspective view of the multi-axial press fabric of the present invention; and Figure 7 is an enlarged schematic view of a portion of the outer surface of the multi-axial press fabric.

Detailed Description of the Preferred Modality Referring now to the different figures, Figure 1 is a schematic top plan view illustrating a method for manufacturing one of the layers of the base fabric of the multiaxial press fabric of the present invention. . The method can be practiced using an apparatus 10 comprising a first roller 12 and a second roller 14, which are parallel to each other and which can be rotated in the directions indicated by the arrows. A strip of woven fabric 16 is wound from a supply roll 18 around the first roll 12 and the second roll 14 in a continuous spiral. It will be recognized that it may be necessary to move the supply roller 18 at a suitable speed along with the second roller 14 (to the right in Figure 1) when the fabric strip 16 is being wound around the rollers 12, 14 The first roller 12 and the second roller 14 are separated at a distance D, which is determined with reference to the total length, C, required for the base fabric layer to be manufactured, the length of the total, C, measures longitudinally (in the machine direction) around the loop shape or endless band of the layer. The woven fabric strip 16, which has a width w, is wound spirally over the first and second rolls 12, 14 in a plurality of turns of the supply roll 18, which can be translated together with the second rolls 14 in the course of the winding. The successive turns of the fabric strip 16 are brought into contact with each other and are joined to one another along a helically adjoining seam by stitching, basting, fusing or welding to produce the base fabric layer 22 as shown in FIG. Figure 2. When a sufficient number of turns of the fabric strip 16 have been made to produce the layer 22 with the desired width, that width is measured transversely (in the cross-machine direction) through the loop or band shape endless layer 22, concludes the spiral winding. The base fabric 22 thus obtained has an internal surface, an external surface, a machine direction and a cross machine direction. Initially, the side edges of the base fabric layer 22 will obviously not be parallel to the machine direction thereof, and they should be cut along the lines 24 to provide the layer 22 with the desired width W, and two lateral edges parallel to the machine direction its endless band loop shape. The fabric strip 16 can be woven with single-filament, single-filament or multi-filament yarns of a synthetic polymeric resin, such as polyester or polyamide, in the same way as other fabrics used in the fabric are woven. industry to make paper. After being woven, they may be termed in a conventional manner prior to interim storage on the supply roll 18. The fabric strip 16 includes longitudinal yarns and transverse yarns, where, for example, the longitudinal threads can be single filament yarns folded, while the transverse yarns can be single filament yarns. In addition, the fabric strip 16 may be a single layer or multiple layer fabric. Alternatively, the fabric strip 16 can be woven and thermosetted in a conventional manner, and fed directly to the apparatus 10 from a thermosetting unit without interim storage * on a supply roll 18. It may also be possible to remove the thermosetting with the selection of the appropriate material and construction of the product (fabric, sizes and yarn numbers). In such a situation, the fabric strip 16 would be fed to the apparatus 10 from a fabric loom without interim storage in a supply roll 18. The fabric strip 16 can also be a non-woven mesh fabric of the variety described in the patent. United States assigned No. 4,427,734 to Johnson, the teachings of which are incorporated herein by reference. The mesh fabric is a structure similar to a network of ridges or threads separated by the mesh. The monofilament-like elements that constitute the mesh fabric are oriented in the longitudinal and transverse divisions of the same. Figure 3 is a cross section of the strip of fabric 16 taken according to what is indicated by line 3-3 in Figure 1. This comprises longitudinal threads 26 and transverse threads 28, both of which are represented as monofilaments, intertwined in a single layer fabric. More specifically, a flat fabric is shown, although, it should be understood, that the fabric strip 16 can be woven according to any of the fabric patterns commonly used to weave fabrics for papermaking machines. Because the fabric strip 16 is wound spirally to assemble the base fabric layer 22, the longitudinal threads 26 and the transverse threads 28 do not align with the machine and cross machine directions, respectively, of the layer 22. Instead, the longitudinal threads 26 are produced at a slight angle,?, Whose magnitude is a measure of the separation of the spiral turns of the fabric strip 16 from the machine direction of the layer 22, as suggested by the top plan view thereof shown in Figure 2. This angle, as noted above, is typically less than 10 °. Because the transverse threads 28 of the fabric strip 16 generally cross the longitudinal threads 26 at an angle of 90 °, the transverse threads 28 produce the same slight angle,?, With respect to the cross machine direction of the layer. 22. The web-woven strip 16 has a first side edge 30 and a second side edge 32 which together define the width of the body of the woven fabric strip 16. When the fabric strip 16 is being wound spirally over the first and second roller 12, 14, the first lateral edge 30 of each turn comes into contact with a second lateral edge 32 of the immediately preceding turn and attached thereto. If desired, a second base fabric layer for the multi-axial press fabric of the present invention may be provided on top of the base fabric layer 22 before removing that base fabric layer 22 from the apparatus 10. The second layer of Base fabric 34 can be designed in the same manner as described above. Preferably, the second base fabric layer 34 is manufactured spirally in a direction opposite to that of the base fabric layer 22 starting on the right side of the second roller 14 in Figure 1, instead of the left side, as would be the case for the manufacture of the base fabric layer 22, and moving the supply roller 18 at a suitable speed to the left along with the second roller 14 when the fabric strip 16 is being wound around the rollers 12, 14. it will be appreciated that the fabric strip 16 will have to be rolled in a sufficient number of turns to completely cover the base fabric layer 22, and that the side edges of the second base fabric layer 34 should be cut to be parallel to the machine direction and to conform to those of the base fabric layer 22. The result is shown in Figure 4, where the helically continuous seam 2C of the base fabric layer 22 is shown as a dotted line. Additional layers may be provided, winding in any direction, in the same manner. Figure 5 is a schematic, amplified view of a portion of the outer surface of the laminated base fabric, two layers, 36. The second layer 34, whose longitudinal (warp) threads 42 and transverse (weft) threads 44 they are represented by solid lines, the first superimposed layer 22, whose longitudinal (warp) threads 38 and transverse (weft) threads 40 are represented by dashed lines. Both longitudinal (warp) threads 38 and longitudinal (warp) threads 42 form a relatively small angle with respect to the machine direction (MD) of the base fabric 36, and, because the first layer 22 and the second layer 34 form spirals in opposite directions, intersecting each other at a relatively small angle that is equal to the sum of the angles each forms with the machine direction. Similarly, both transverse (weft) 40 and transverse (weft) 44 threads form small angles with respect to the machine-transverse direction (CD) of the base cloth 36, and intersect each other at a relatively angle small that is equal to the sum of the angles that each one produces with the direction transversal to the machine. As a consequence, the two-layer laminated base fabric 36 does not have threads in machine direction or transverse to the machine, defined. Instead, the longitudinal (warp) threads 38 and the cross (weft) threads 40 of the first layer 22 and the longitudinal (warp) threads 42 and the transverse (weft) threads 44 of the second layer 34 are They find in four different directions at oblique angles to the directions of the machine and transverse to the machine. For this reason, base 36 is considered to be multiaxial. Figure 6 is a perspective view of a multi-axial press fabric 46 of the present invention. The press fabric 46 is in the form of an endless loop or band having an inner surface 48 and an outer surface 50, and comprises a base fabric 36. The outer surface 50 of the multi-axial press fabric 46 has a plurality of layers of cut fiber material attached to it by stitching. The seam of the layers of the fiber material cut on the outer surface 50 of the press fabric 46 also joins the first and second layers 22, 34 of the base fabric 36 with each other, since the seam directs the individual fibers of the base material. fiber cut in and through the first and second superposed layers 22, 34. The cut fiber material may be polyamide, polyester or any other variety of staple fiber used by those skilled in the art for manufacturing fabrics for papermaking machines . In general, one or both of the inner and outer surfaces of the press fabric has a plurality of layers of cut fiber material bonded thereto by sewing. Within each of the plurality of layers of staple fiber material, the fibers are predominantly oriented at oblique angles with respect to the machine direction of the multiaxial press fabric 46, except, of course, where they have been directed towards through the first and second layers 22, 34 of the base fabric 36 in a direction essentially perpendicular thereto through the seam. Figure 7 is an elongated schematic view of a portion of the outer surface 50 of the press fabric 46. The individual fibers in the plurality of layers of cut fiber material are predominantly oriented in the directions suggested by the criss-cross lines in the figure . These directions are at oblique angles in relation to the direction of the machine, and so on, therefore, except for the portions of individual fibers directed towards the base fabric 36 by the seam, the fibers are predominantly oriented at oblique angles in relation to the machine direction of the multiaxial press fabric 46, and they are substantially parallel to each other in those directions. The fibers in the layers immediately superimposed or underlying any given layer are predominantly oriented in the other of the two directions, as suggested by the crosslinked pattern of Figure 7. The plurality of layers of cut fiber material is assembled from In accordance with the teachings of commonly assigned U.S. Patent Nos. 3,879,820 and 3,920,511 to Grieves et al., the teachings of which are incorporated herein by reference. These patents, which are related by having been issued split applications of a common original application, show a non-woven papermaking fabric that lacks a base fabric. The papermaking fabric is produced by cross-superposing a block of staple fiber, the fibers of which are initially parallel to each other in the longitudinal direction of the cut fiber block, on the floor to produce a sheet having several layers of staple fiber block. . In each of the different layers of the sheet, the fibers are oriented predominantly at an angle of 45 ° to 85 ° with respect to their longitudinal direction. The sheet is then consolidated to give it some structural integrity, at which time the fibers in each layer are oriented at an angle of approximately 66 ° in relation to the longitudinal direction of the sheet. The sheet is then overlapped again, this time to a width equal to that desired for the nonwoven fabric. The fabric, which comprises several superimposed layers of the sheet, is then sewn. The fibers in each fabric factory, having been subjected to two successive overlap operations, are in directions forming an angle of 10 ° to 40 ° in relation to the longitudinal direction. It should be understood that the angular intervals discussed in the preceding paragraphs are determined by the parameters of the machine to effect the overlap actually used to manufacture the fabric. In any case, the fibers in each layer of the fabric are oriented predominantly in directions that form an oblique angle in relation to the longitudinal direction thereof. The plurality of layers of cut fiber material sewn to the base fabric 36 to produce the multiaxial press fabric 46 of the present invention are assembled according to the teachings of those patents and with a width equal to that of the base fabric 36, and they are longitudinally deposited around the outer surface of the base cloth 36 and sewn thereon, to produce the multiaxial base fabric 46 of the present invention. As advantages, the present invention features improved gauge retention, superior long-term water pressure handling and distribution, ease of cleaning, superior sheet finishing and improved cross-machine profile. Modifications to the multiaxial press fabric of the present invention will be obvious to those skilled in the art, or would not carry the invention thus modified beyond the scope of the appended claims. For example, the base fabric thereof may comprise, in addition to one or more spirally wound layers, one or more layers of standard base fabric. That is, one or more additional layers may be formed by fabrics having yarns in the machine direction and transverse to the machine and produced by techniques well known to those skilled in the art. Such a fabric can be woven endlessly in the dimensions required for the papermaking machine for which it is intended, or woven in a flat form and subsequently converted into an endless form with a woven seam. They can also be produced by a modified endless weaving technique for sewing on the machine. Laminated fabrics can also be used, having one or more layers of standard base fabric.

In addition, the multiaxial press fabrics of the present invention may also include one or more layers of standard staple fiber material, the individual fibers of which have a more random orientation as compared to those of an angular network; randomized cut fiber material; or cut fiber material oriented longitudinally.

Claims (40)

CHAPTER CLAIMING Having described the invention, it is considered as a novelty and, therefore, what is claimed is contained in the following CLAIMS:

1. A multi-axial press fabric for the pressing section of a papermaking machine, the multi-axial press fabric is characterized in that it comprises: a base fabric, the base fabric has a first layer, the first layer comprises a first fabric strip, the first fabric strip has a first side edge and a second side edge, the first fabric strip is spirally wound in a plurality of contiguous turns, where the first side edge in one turn of the first fabric strip comes into contact with the second lateral edge of an adjacent turn thereof, thereby forming a helically continuous seam separating the adjacent turns of the first strip of fabric, the helically continuous seam is closed by contacting the first and second side edges of the first strip of contact together. fabric together, thereby providing the first layer in the base fabric with the shape of an endless loop or band having a machine direction, a direction transverse to the machine, an internal surface and an external surface; and a plurality of layers of cut fiber material bonded to one of the inner and outer surfaces of the base fabric, the fibers in each of the plurality of layers of cut fiber material are predominantly oriented substantially parallel to each other in a plurality of layers of cut fiber material. direction that forms an oblique angle with respect to the direction of the machine, the oblique angle is the same for each of the plurality of layers, and the direction for each of the plurality of layers has an opposite direction to that of any layer immediately underlying or superimposed, to produce a reticulated angular network.

2. The multi-axial press fabric according to claim 1, characterized in that the first strip of fabric is woven from longitudinal and transverse threads.

3. The multi-axial press fabric according to claim 1, characterized in that the first strip of material is a non-woven mesh fabric having longitudinal and transverse elements.

The multiaxial pressing fabric according to claim 1, characterized in that the base fabric further comprises a second layer, the second layer comprises a second strip of fabric, the second strip of fabric has a first side edge and a second one. lateral edge, the second fabric strip is wound spirally in a plurality of contiguous turns, where the first side edge in one turn of the second fabric strip comes into contact with the second side edge of an adjacent turn of the same, forming by Thus a helically continuous seam separating the adjacent turns of the second fabric strip, the helically continuous seam is closed by contacting the first and second side edges of the second fabric strip together, thereby providing the second layer in the base fabric the shape of an endless loop or band having a machine direction, a cross machine direction, an inner surface and an outer surface, the endless loop or band formed by the second layer is nested within the loop or endless band formed by the first layer.

5. The multi-axial press fabric according to claim 4, characterized in that the second fabric strip is wound spirally in a direction opposite to that in which the first fabric strip is spirally wound.

The press fabric according to claim 4, characterized in that the second strip of fabric is woven from longitudinal and transverse threads.

7. The press fabric according to claim 4, characterized in that the second strip of material is a non-woven mesh fabric having longitudinal and transverse elements.

8. The multi-axial press fabric according to claim 4, characterized in that the base fabric further comprises at least one additional layer, the additional layer comprises a strip of fabric, the strip of fabric has a first side edge and a second side edge, the additional fabric strip is wound spirally in one direction. plurality of contiguous turns, wherein the first lateral edge on one turn of the additional fabric strip comes into contact with the second side edge of an adjacent turn thereof, thereby forming a helically continuous seam separating the adjacent turns of the additional fabric strip, the helically continuous seam is closed by contacting the first and second side edges of the additional fabric strip together, thereby providing the additional layer with the shape of an endless loop having a direction of the machine, a direction transverse to the machine, an internal surface and an external surface, the loop or endless band formed by the additional layer is nested within the loops or endless band formed by the first layer and second layer.

9. The press fabric according to claim 8, characterized in that the additional fabric strip is woven from longitudinal and transverse threads.

The multi-axial press fabric according to claim 8, characterized in that the additional fabric strip is a non-woven mesh fabric having longitudinal and transverse elements.

The multiaxial press fabric according to claim 1, characterized in that the base fabric further comprises a standard base fabric having yarns in machine direction and yarns in transverse direction to the machine, the standard base fabric is in shape of an endless loop or band having a machine direction, a machine-transverse direction, an inner surface and an outer surface.

12. The multi-axial press fabric according to claim 11, characterized in that the loop or endless band formed by the standard base fabric is nested within the loop or endless band formed by the first layer.

13. The multi-axial press fabric according to claim 11, characterized in that the standard base fabric is endless.

14. The multiaxial pressing fabric according to claim 11, characterized in that the standard base fabric can be sewn on the machine.

15. The multi-axial press fabric according to claim 2, characterized in that the first strip of fabric is made of a single-layer fabric.

16. The multi-axial press fabric according to claim 2, characterized in that the first fabric strip is made of a multilayer fabric.

17. The multiaxial pressing fabric according to claim 2, characterized in that the longitudinal threads and the transverse threads of the first strip of fabric are made of a synthetic polymeric resin.

18. The multi-axial press fabric according to claim 1, characterized in that the first layer of the base fabric has side edges cut in a direction parallel to the machine direction thereof.

19. The multi-axial press fabric according to claim 1, characterized in that the first fabric strip forms an angle of less than 10 ° with respect to the machine direction of the first layer.

20. The multi-axial press fabric according to claim 6, characterized in that the second fabric strip is made of a single layer fabric.

21. The multiaxial press fabric according to claim 6, characterized in that the second fabric strip is made of a multilayer fabric.

22. The multi-axial press fabric according to claim 6, characterized in that the longitudinal threads and the transverse threads of the second fabric strip are made of a synthetic polymeric resin.

23. The multi-axial press fabric according to claim 4, characterized in that the second layer of the base fabric has side edges cut in a direction parallel to the machine direction thereof.

24. The multi-axial press fabric according to claim 1, characterized in that the second fabric strip forms an angle of less than 10 ° with respect to the machine direction of the second layer.

25. The multi-axial press fabric according to claim 9, characterized in that the additional fabric strip is made of a single layer fabric.

26. The multi-axial press fabric according to claim 9, characterized in that the additional fabric strip is made of a multilayer fabric.

27. The multi-axial press fabric according to claim 9, characterized in that the longitudinal threads and the transverse threads of the additional fabric threads are made of a synthetic polymeric resin.

28. The multiaxial pressing fabric according to claim 8, characterized in that the additional layer of the base fabric has side edges cut in a direction parallel to the machine direction thereof.

29. The multi-axial press fabric according to claim 8, characterized in that the additional fabric strip forms an angle of less than 10 ° with respect to the machine direction of the layer.

30. The multi-axial press fabric according to claim 11, characterized in that the standard base fabric is made of a single layer fabric.

31. The multiaxial press fabric according to claim 11, characterized in that the standard base fabric is a multi-layer fabric.

32. The multi-axial press fabric according to claim 11, characterized in that the standard base fabric is laminated.

33. The multiaxial pressing fabric according to claim 11, characterized in that the longitudinal threads and the transverse threads of the standard base fabric are made of a synthetic resin.

34. The multi-axial press fabric according to claim 1, characterized in that it also comprises a plurality of layers of cut fiber material attached to each other of the internal and external surfaces of the base fabric, the fibers of the second layer. one of the plurality of layers of cut fiber material are predominantly oriented substantially parallel to each other in a direction that produces an oblique angle with respect to the machine direction, the oblique angle in each of the plurality of layers is substantially the same, and the direction in each of the plurality of layers has an opposite orientation to that of any layer immediately underlying or superimposed-, to produce a cross-linked angular network.

35. The multi-axial press fabric according to claim 1, characterized in that it further comprises a plurality of layers of cut fiber material attached to one of the inner and outer surfaces of the base fabric by stitching, the cut fiber material it is selected from the group consisting of standard staple fiber material, standard randomized fiber material, and longitudinally oriented cut fiber material.

36. The multiaxial pressing fabric according to claim 35, characterized in that it also comprises a plurality of layers of cut fiber material attached to each other of the internal and external surfaces of the base fabric by stitching, the fiber material cut is selected from the group consisting of standard staple fiber material, randomized staple fiber material, and longitudinally oriented staple fiber material.

37. The multi-axial press fabric according to claim 1 or claim 34, characterized in that the cut fiber material is made of a polymeric resin material.

38. The multiaxial press fabric according to claim 37, characterized in that the polymeric resin material is selected from the group consisting of polyamide and polyester resins.

39. The multi-axial press fabric according to claim 35 or claim 36, characterized in that the cut fiber material is made of a polymeric resin material.

40. The multiaxial press fabric according to claim 39, characterized in that the polymeric resin material is selected from the group consisting of polyamide and polyester resin.