Patent Publication Number: US-2007119513-A1

Title: Woven fabric structure

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a woven fabric structure including at least one array of warp yarns interwoven with at least one array of substantially orthogonally extending weft yarns, wherein each end of a warp yarn is extended beyond the last weft yarn to form either a binder or a seam loop which can be interdigitated with similar seam loops of the opposing fabric end and joined by at least one pintle wire passed through a tunnel formed by the interdigitated seam loops.  
      2. Description of the Related Art  
      The woven fabric is for papermachine clothing, such as a forming fabric, a press sleeve, an extended nip press belt, a dryer fabric, a base cloth, for a filter belt or for a conveyor belt.  
      A common form of seam is achieved by extending selected longitudinal (machine direction) warp yarns of the fabric beyond the last transverse (cross-machine direction) weft yarn to form a loop, the end of which is back-woven into the fabric. The non-selected machine direction warp yarns are looped about the last cross-direction weft yarn the end of which is woven and the end back-woven into the fabric. Such a fabric structure is described in the British Patent Application GB-A-1,488,815, which discloses two patterns of weaving back the looped yarns and cutting short of certain other machine direction yarns to provide space for the back woven loop ends.  
      All warp yarns usually have the same thickness or width, so that as a result when using only half the warp yarns to form the loops, to afford space for interdigitation of the corresponding loops of the opposite end of the fabric, the tensile strength of the seam is significantly less than the fabric strength and there is a higher propensity in the seam region for marking the material sheet due to the greater open area in the seam region, as about 50% of the total width of the fabric is open space.  
      One approach of solving this problem is to use more than 50% of the warp yarns to form loops. An example of this is the International Patent Application WO 92/15743 A1 wherein the problem of obtaining space for interdigitation of loops where more than 50% space is used by the loops of each side is tackled by crossing adjacent loops over each other. However, the use of more than 50% warp yarns and the crossing of the looped yarns make the already complicated, prolonged, and expensive seaming process even more protracted.  
      Finally, the European Patent Specification EP 1 070 164 B1 discloses a woven fabric structure including an array of warp yarns interwoven with an array of substantially orthogonally extending weft yarns using warp yarns of differing widths. The warp yarns include groups of relatively wide warp yarns and groups of relatively thin warp yarns, said groups of relatively wide warp yarns alternating with said groups of relatively thin warp yarns. The groups of relatively wide and relatively thin warp yarns each include two or more respectively wide or thin warp yarns and said relatively wide warp yarns are extended in a seam region to provide seaming loops on each end of the fabric. The disadvantage of this woven fabric structure is that warp yarns of different size can produce an uneven fabric surface leading to marking of the material sheet.  
      What is needed in the art is a woven fabric structure with an improved tensile strength, less open space and a reduced propensity in the seam region for marking the material sheet.  
     SUMMARY OF THE INVENTION  
      The present invention provides that the seam loops and the binders of the warp yarns possess a ratio above 1:1 and below 4:1.  
      This ratio provides a woven fabric structure with an improved tensile strength, a lower open space, and a reduced propensity in the seam region for marking the material sheet.  
      The ratio of the seam loops to the binders is 3:1, 2:1, or 3:2. The ratio of “3:1” means three seam loops, one binder, three seam loops, one binder, three seam loops, etc. The ratio of “2:1” means two seam loops, one binder, two seam loops, one binder, two seam loops, etc. The ratio of “3:2” means either two seam loops, one binder, one seam loop, one binder, two seam loops, one binder, one seam loop, one binder, two seam loops, etc. or three seam loops, two binders, three seam loops, two binders, three seam loops, etc. These three ratios provide highly improved tensile strengths with significant lower open spaces. The propensity in the seam region for marking the material sheet is consequently reduced.  
      According to two embodiments of the present invention, the warp yarns for the seam loops are flat or profiled yarns with overall dimensions between 0.25 and 1.00 mm in height and between 0.50 and 2.00 mm in width, or they are round yarns with a diameter between 0.25 and 1.00 mm. Furthermore, the warp yarns are of a circular, rectangular, or other profile shaped cross-section. The other profile shaped cross-section will have the shape of a triangle, semicircle, hexagon, octagon, or parallelogram.  
      Moreover, according to an embodiment of the present invention the warp yarn has a cross-sectional area between 0.125 and 2.00 mm 2  for the flat or profiled yarns and between 0.05 and 0.79 mm 2  for the round yarns. These ranges guarantee a reduced propensity of the woven fabric structure and, therefore, a reduced marking of the material sheet. The material sheet is a paper, board, or tissue sheet.  
      In order to significantly reduce marking of the material sheet, the warp yarns and the weft yarns have the same, similar, or different shapes and cross-sectional areas.  
      The present invention further provides papermachine clothing formed by seaming a woven fabric structure according to the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:  
       FIGS. 1-3  are three fragmentary, enlarged, detail views of parts of seam regions of woven fabrics, showing parts of the weave structures of the fabrics of the seam formations;  
       FIG. 4  is a fragmentary, enlarged, detail view of part of a seam region of a woven fabric, showing part of the weave structure of the fabric of the seam formation; and  
       FIGS. 5-7  are three fragmentary, enlarged, detail views of parts of seam regions of woven fabrics according to the invention, showing parts of the weave structures of the fabrics of the seam formations. 
    
    
      Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.  
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now to the drawings, and more particularly to  FIGS. 1-4 , there is shown a woven fabric structure for a papermachine clothing or another belt, such as a filter or conveyor belt, including an array of cross-machine direction weft yarns  10 , extending parallel to an edge of the fabric  1 , and a last weft yarn  10   a , defining the edge. An array of warp yarns  12  is woven through the weft yarns  10  substantially orthogonally to the weft yarns  10  of, and in machine direction of, the fabric  1 .  
      It is shown in the embodiment of  FIG. 1 , which shows a fragmentary, enlarged, detail view of part of a seam region of a woven fabric  1 , that a normal loop seam is made by reweaving the first machine direction warp yarn  12 . 1  back into the fabric  1  to form a loop  14 . The second machine direction warp yarn ( 12 . 2  is not visible) is brought out of the fabric within the seam area. This leaves a space for the first machine direction warp yarn to replace the pathway of the second machine direction warp yarn. The third machine direction warp yarn  12 . 3  is then rewoven back into the fabric to form a binder by replacing the path of the fourth machine direction warp yarn  12 . 4 . The process is repeated so that 50% of the seam includes loops  14  and 50% of the seam includes binders  16 .  
      The seam loops  14  and the binders  16  are interdigitated with similar seam loops  14  of the opposing fabric end and joined by a pintle wire  18  passed through a tunnel  20  formed by the interdigitated seam loops  14 .  
      Another possibility to join two fabric ends together is the use of a spiral connecting the seam loops of the two opposing fabric ends. A spiral is used in connecting the seam loops of the two opposing fabric ends of a dryer fabric.  
      Furthermore, according to the embodiment of  FIG. 2 , some designs of fabrics  1  have two layers A, B of thin machine direction warp yarns  22 . The seam loops  24  are made by reweaving one machine direction warp yarn  22 . 1  of the first layer A back into the fabric  1  to form a seam loop  24  by replacing the path of the second machine direction warp yarn  22 . 2  of the second layer B. The third machine direction warp yarn  22 . 3  is then rewoven back into the fabric  1  of the first layer A to form a binder  26  by replacing the path of the fourth machine direction warp yarn  22 . 4  of the second layer B. The process is repeated so that 50% of the seam is includes seam loops  24  and 50% of the seam includes binders  26 . A fabric  1  of this design is disclosed in the European Patent Specification EP 0 612 881 B1.  
      As shown in  FIG. 3 , it is also possible to increase the number of seam loops  34  by making a seam without binders  36  so that 50% of the seam forms seam loops  34  around a pintle wire  38   a . Then 50% of the seam forms seam loops  34  around a second pintle wire  38   b.    
       FIG. 4  shows another fragmentary, enlarged, detail view of part of a seam region of a woven fabric  1 , showing part of the weave structure of the fabric  1  of the seam formation. The seam loops  44  and the binders  46  of the warp yarns  42  possess a ratio R of 1:1, e.g. one seam loop  44 , one binder  46 , one seam loop  44 , one binder  46 , one seam loop  44 , etc. Additionally, the warp yarns  42  for the seam loops  44  are either flat or profiled yarns with overall dimensions between 0.25 and 1.00 mm in height and between 0.50 and 2.00 mm in width, or they are round yarns with a diameter between 0.25 and 1.00 mm. A practical embodiment will have over 48 seam loops  44  with a width of 100 mm and 11.52 mm 2  cross-sectional area F in total.  
      Additional fragmentary, enlarged, detail views of parts of seam regions of woven fabrics  1  are shown in  FIGS. 5, 6  and  7 . Each fabric  1  includes an array of cross-machine direction weft yarns  100 , extending parallel to an edge of the fabric  1 , and includes a last weft yarn  100   a , defining the edge. An array of warp yarns  102  is woven through the weft yarns  100  substantially orthogonally to the weft yarns  100  of and in machine direction of the fabric  1 .  
      Each end of a warp yarn  102  is extended beyond the last weft yarn  100   a  to form either a binder  106  or a seam loop  104  which can be interdigitated with similar seam loops  104  of the opposing fabric end and joined by a pintle wire  108  passed through a tunnel  110  formed by the interdigitated seam loops  104 .  
      The seam loops  104  and the binders  106  of the warp yarns  102  possess a ratio R above 1:1 and below 4:1. For example, the ratio R can be 2:1 as shown in  FIG. 5  or 3:2 as shown in  FIGS. 6 and 7 . According to the first ratio R, the warp yarns  102  have two seam loops  104 , one binder  106 , two seam loops  104 , one binder  106 , two seam loops  104 , etc. According to the second ratio R, the warp yarns  102  have three seam loops  104 , two binders  106 , three seam loops  104 , two binders  106 , three seam loops  104 , etc. or two seam loops  104 , one binder  106 , one seam loop  104 , one binder  106 , two seam loops  104 , etc. These two ratios provide highly improved tensile strengths with significant lower open spaces. The propensity in the seam region for marking the material sheet is consequently reduced.  
      Additionally, the warp yarns  102  for the seam loops  104  are either flat or profiled yarns with overall dimensions between 0.25 and 1.00 mm in height and between 0.50 and 2.00 mm in width or are round yarns with a diameter between 0.25 and 1.00 mm. The warp yarns  102  of both embodiments are of a circular, rectangular or other profile shaped cross-section C and have a cross-sectional area F between 0.125 and 2.00 mm 2  for the flat or profiled yarns and between 0.05 and 0.79 mm 2  for the round yarns. A practical embodiment with a ratio of 2:1 will have over 64 seam loops  104  with a width of 100 mm and 15.36 mm 2  cross-sectional area F in total (0.36 mm in height and 0.67 mm in width). This is a 33% increase in material around the seam pintle with respect to the embodiment of  FIG. 4 .  
      Moreover, the warp yarns  102  and the weft yarns  104  have the same, similar, or different shapes S and cross-sectional areas F.  
      The woven fabric  1  can be used for papermachine clothing, such as a forming fabric, a press sleeve, an extended nip press belt, a dryer fabric, a base cloth, for a filter belt or for a conveyor belt.  
      While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.  
     REFERENCE NUMERALS LIST  
     
         
         
           
               1  fabric  
               10  weft yarn  
               10   a  last weft yarn  
               12  warp yarn  
               12 . 1  warp yarn  
               12 . 2  warp yarn  
               12 . 3  warp yarn  
               12 . 4  warp yarn  
               14  seam loop  
               16  binder  
               18  pintle wire  
               20  tunnel  
               22  warp yarn  
               22 . 1  warp yarn  
               22 . 2  warp yarn  
               22 . 3  warp yarn  
               22 . 4  warp yarn  
               24  seam loop  
               26  binder  
               34  seam loop  
               36  binder  
               38   a  pintle wire  
               38   b  pinte wire  
               42  warp yarn  
               44  seam loop  
               46  binder  
               100  weft yarn  
               100   a  last weft yarn  
               102  warp yarn  
               104  seam loop  
               106  binder  
               108  pintle wire  
               110  tunnel  
              A first layer  
              B second layer  
              C cross-section  
              F cross-sectional area  
              R ratio  
              S shape