Abstract:
A fabric for use in a paper machine includes a pair of ends connected together in a join area to make an endless loop of fabric, the join area having a plurality of perforations extending therethrough.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a division of U.S. patent application Ser. No. 11/510,476, entitled “METHOD AND JOINING ASSEMBLY FOR JOINING ENDS OF A FABRIC IN A PAPER MACHINE”, filed Aug. 25, 2006, which is incorporated herein by reference. U.S. patent application Ser. No. 11/510,476 is a non-provisional application based upon U.S. provisional patent application Ser. No. 60/711,584, entitled “IMPROVED METHOD TO JOIN BASE FABRIC FOR PMC APPLICATIONS”, filed Aug. 26, 2005, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]    The present invention relates to paper machine clothing, and, more particularly, to a fabric for use in a press section of a paper machine. 
       BACKGROUND OF THE INVENTION 
       [0003]    Generally speaking, a paper machine is made up of three sections, namely the forming section, press section and dryer section. In each section an endless engineered fabric is used to transport a continuous paper sheet through the paper machine. The structure of the fabrics for each section differs, as the functions of each section of the paper machine are different. 
         [0004]    The fiber suspension is discharged in a fine, even, cross-machine stream onto a porous wire in the forming section, typically known as a fourdrinier wire. Water drains via gravity through the wire from the fiber suspension. A press fabric for the press section must be capable of rapidly absorbing and expelling water while supporting the newly formed paper sheet. By the time the paper web enters the drying section from the press section as much as fifty percent of the water has been removed from the web. The remaining water removal is completed in the dryer section. The paper web is carried by dryer fabrics transferring the web in succession to rotating dryer cylinders arranged along the length of the dryer section and is heated by high pressure steam circulated within the dryer cylinders. 
         [0005]    Endless woven fabrics as described above require special weaving looms, making the fabrics costly and slow to manufacture. The ends of the fabric are joined together using, e.g., thermoplastic welding; however, joining by thermoplastic welding may be unreliable, has a relatively high rate of failure, may result in a weak joint, has poor wear resistance, and has poor caliper and porosity variation. If the fabric ends are “butted” together, the join area is prone to gap open as the felt elongates, or stretches, on the paper machine during use. 
         [0006]    U.S. Pat. No. 5,731,063 (Schultz et al.) discloses a paper making felt and substrate which is bonded together with a fuse bonded joint using ultrasonic welding. Referring to  FIG. 8 , the ends of a substrate are clamped between stabilizing strips  64 , and ultrasonic welder  75  welds the ends together. The heat generated by the ultrasonic welding renders the substrate substantially impermeable in the joint area. 
         [0007]    PCT/GB89/00681 discloses a method for manufacturing a fabric for use in a paper making machine, wherein free ends  12 ,  13  of fabric  11  are folded over, butted together, and then sewn to the adjacent portion of the fabric ( FIG. 2 ). The loops  17 ,  18  at the opposite ends of the fabric created by folding ends  12 ,  13  are joined together by inserting a pintle wire  19  through the loops  17 ,  18 . Pintle wire  19  of course increases the physical size of the fabric in the join area. 
         [0008]    What is needed in the art is a method and corresponding apparatus for joining ends of a fabric together which is simple, reliable and cost effective. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides a method and assembly for joining two ends of a fabric, in which the two ends are held in a join area by a pin plate and joined adhesively or mechanically to create an endless loop of fabric. 
         [0010]    The invention comprises, in one form thereof, a method of joining two ends of a fabric for use in a paper machine, including the steps of: placing a first end of the fabric on a first portion of a pin plate, the pins in the first portion of the pin plate extending into the first end; placing a second end of the fabric on a second portion of the pin plate such that the first end and the second end are in close proximity to each other in a join area, the pins in the second portion of the pin plate extending into the second end; and joining the first end and the second end in the join area, thereby creating a join that is more homogeneous with the body of the fabric, as the pins prevent the adhesive from “sealing” the fabric to the joined area and with relatively uniform caliper. 
         [0011]    The invention comprises, in another form thereof, a joining assembly for joining two ends of a fabric for use in a paper machine. A pin plate has a plurality of outwardly extending pins. The pin plate includes a first portion and a second portion. A first end of the fabric is placed on the first portion of the pin plate, whereby the pins in the first portion of the pin plate extend into the first end. A second end of the fabric is placed on the second portion of the pin plate such that the first end and the second end are in close proximity to each other in a join area. The pins in the second portion of the pin plate extend into the second end. A joining device joins the first end and the second end in the join area. 
         [0012]    Advantages of the present invention include an improved fabric join for woven and non-woven substrates having a uniform caliper, uniform density, uniform porosity, and superior strength and durability. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    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 an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0014]      FIG. 1  is a perspective view of an embodiment of a joining assembly of the present invention, used to carry out the method of the present invention for joining ends of a fabric together; 
           [0015]      FIG. 2  is a top view of the joining assembly shown in  FIG. 1 ; and 
           [0016]      FIG. 3  is a side view of the joining assembly shown in  FIGS. 1 and 2 . 
           [0017]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring now to the drawings, there is shown an embodiment of a joining assembly  10  of the present invention, used for joining a first end  12  of fabric  16  with a second end  14  of fabric  16  for use in a paper machine (not shown). Fabric  16 , shown in more detail in  FIGS. 2 and 3 , is in the form of a woven press fabric for use in a press section of the paper machine, but may be differently configured depending upon the application. For example, fabric  16  may be a different type of woven fabric, or may be a non-woven fabric depending upon the application. 
         [0019]    Joining assembly  10  generally includes a pin plate  18  and a joining device  20  which are used for joining first end  12  and second end  14  together such that fabric  16  defines an endless loop. 
         [0020]    Fabric  16  has a machine direction (MD)  22  and a cross-machine direction (CD)  24 . Fabric  16  has a width in the cross-machine direction  24  which may vary depending upon the application. For example, fabric  16  may have a width in the cross-machine direction  24  of between approximately 1 meter in the case of a pilot paper machine to up to 10 meters in the case of a production paper machine. 
         [0021]    Pin plate  18  has a width which is slightly wider than the corresponding width of fabric  16  in the cross-machine direction  24 . However, pin plate  18  may also have a width which is less than the width of fabric  16  in the cross-machine direction, and be used in an endwise sequential manner across the width in the cross-machine direction  24  of fabric  16 . 
         [0022]    Pin plate  18  includes a base  26  and a plurality of pins  28  which extend outwardly from base  26 . Base  26  may be made from any suitable material, such as metal, a suitable composite, nylon, etc. Pins  28  are preferably metal pins, but could be made from any suitable material such as plastic, etc. The exact configuration of pins  28 , as well as the attachment method between pins  28  and base  26  can vary, depending upon the application. Pin plate  18  is subdivided into a first portion  30  and a second portion  32 . First end  12  of fabric  16  is received in first portion  30 , and second end  14  of fabric  16  is received in second portion  32 . A join area  34  lying in coincidence with a sub-portion of each of first portion  30  and second portion  32  defines an area in which first end  12  and second end  14  are in close proximity to each other and permanently joined together, as will be described in more detail hereinafter. 
         [0023]    Joining device  20  is schematically shown as a block in  FIG. 1 , and either adhesively or mechanically bonds first end  12  and second end  14  together. When configured as an adhesive applicator, joining device  20  may apply an adhesive such as an elastomer, a thermal setting polymer or a thermal plastic to join area  34 . In one embodiment, joining device  20  is an adhesive applicator which applies an adhesive to join area  34 , and a mating cover  36  overlying pin plate  18  is used to set the correct thickness of the elastomer and cure the elastomer. 
         [0024]    In the event that joining device  20  is configured to mechanically bond first end  12  and second end  14  together, then joining device  20  is preferably configured as a needle puncher for mechanically bonding first end  12  and second end  14  together. In this case, an optional scrim  38  ( FIG. 1 ) may also be used in joining first end  12  and second end  14  together. Scrim  38  is applied to join area  34  (as indicated by the dashed line) and needle punched together with first end  12  and second end  14  using joining device  20  in the form of a needle puncher. 
         [0025]    An embodiment of the method of the present invention for joining first end  12  with second end  14  will now be described in greater detail. For the described joining method, it is assumed that fabric  16  is a woven press fabric, and joining device  20  is an adhesive applicator. 
         [0026]    First end  12  and second end  14  of fabric  16  are first fringed by removing fibers in the cross-machine direction  24  using a suitable fringing technique. First end  12  is placed on first portion  30  of pin plate  18  such that pins  28  extend into and through first end  12 . Similarly, second end  14  is placed on second portion  32  of pin plate  18  such that pins  28  extend into and through second end  14 . The fringed ends of first end  12  and second end  14  (i.e., the fibers of first end  12  and second end  14  extending in machine direction  22 ) are positioned to overlap with each other in join area  34  (see  FIG. 2 ) between approximately 1 mm to 12 mm, preferably approximately 3 mm (also corresponding to the width of join area  34 ). Adhesive applicator  20  then applies an elastomer adhesive over joined area  34 . Cover  36  is placed over pin plate  18  and is positioned relative to pin plate  18  to provide a desired thickness of the elastomer. Cover  36  is held in place while the elastomer cures, and may also optionally be heated to assist in the curing process. Cover  36  and pin plate  18  are then removed from fabric  16 , which is then ready for use in the press section of a paper machine. After being joined, join area  34  has a maximum thickness of not more than 2.5 times the thickness of fabric  16  (outside join area  34 ), and a minimum thickness of not less than the thickness of fabric  16  (outside join area  34 ). Join area  34  is permeable to air and water. 
         [0027]    In the embodiment of the joining method described above, first end  12  and second end  14  are fringed prior to joining using joining assembly  10  of the present invention. However, it will be appreciate that first end  12  and second end  14  need not be fringed, depending upon the application. Further, in the embodiment of the joining method described above, pin plate  18  extends along cross-machine direction  24  of fabric  16 . It will also be appreciated that joining assembly  10  may be used for joining a fabric  16  along machine direction  22 , or may also be used at an angled bias to cross-machine direction  24  (such as if first end  12  and second end  14  are formed with a tail). 
         [0028]    While this invention has been described as having a preferred design, 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.