Abstract:
An open ended papermaker&#39;s fabric woven from longitudinal and transverse thread systems and including a plurality of seam loops at each end. Two additional transverse threads are interwoven with the longitudinal thread system in the seam zone. The crossover points of the two additional transverse threads occur at a transition between paired paper and machine side threads of the longitudinal thread system which are separated in the transverse direction by at least three top layer longitudinal threads.

Description:
This application claims the benefit of: U.S. Provisional Application Serial No. 60/098,547, filed Aug. 31, 1998; U.S. Provisional Application Serial No. 60/097,831, filed Aug. 31, 1998; U.S. Provisional Application Serial No. 60/098,566, filed Aug. 31, 1998; U.S. Provisional Application Serial No. 60/098,567, filed Aug. 31, 1998; and U.S. Provisional Application Serial No. 60/098,573, filed Aug. 31, 1998. 
    
    
     BACKGROUND 
     The present invention generally relates to an open ended, woven fabric which is designed for use in a papermaking, cellulose or board manufacturing machine. The fabric has a plurality of loops at each end to form a seam for rendering the fabric endless. 
     As will be known to those skilled in the art, papermaking machines generally include three sections commonly referred to as the forming, press and dryer sections. The present invention finds particular application in the press section of a papermaking machine. 
     Typically, press felts include a supporting base, such as a woven fabric, and a paper carrying or supporting layer. Frequently, the paper support layer is a homogeneous, non-woven batt that has been affixed to the base. Base fabrics are typically woven fabrics which are used as an endless loop. Such an endless loop fabric may be woven endless with no seam or the fabric may be woven with two ends which are joined by a seam. Typical seams include pin type seams which utilize a pintle inserted through seam loops to close the fabric. 
     Some prior art seams have employed threads in the seam area to increase batt adhesion. However, these efforts have not always produced the desired contact area or the desired interconnection between paper and machine side machine direction threads. 
     As a result, there exists a need in seam loop construction to provide increased surface contact in the seam zone for better batt anchorage and a better interconnection between the paper and machine sides. 
     SUMMARY 
     The present invention relates to an open ended papermaker&#39;s fabric of a type woven from a longitudinal thread system and a transverse thread system. A plurality of seam loops are formed at each end of the fabric by the threads of the longitudinal thread system. A seam zone exists at each end of the fabric between the respective seam loops and the last thread of the transverse thread system. At least one, but preferably two, additional transverse threads are interwoven in at least one seam zone with the longitudinal thread system. The additional threads may be woven in a repeat pattern that includes at least twelve adjacent paper side longitudinal threads, at least one machine side interlacing and a portion that weaves continuously with at least five adjacent paper side longitudinal threads. The continuous weave portion may include at least to identical subrepeats. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a portion of the longitudinal seam loops in a fabric having additional cross machine direction threads in accordance with the present invention. 
     FIG. 2 is a front elevation of the seam loops and additional threads shown in FIG.  1 . 
     FIG. 3 illustrates one weave repeat pattern for one of the additional threads. 
     FIG. 4 illustrates one weave repeat for a second additional thread. 
     FIG. 5 shows the weave repeats of FIGS. 3 and 4 combined but without the seam loops as shown in FIG.  2 . 
     FIG. 6 is a top plan view of the combined weave patterns as illustrated in FIGS. 1,  2  and  5 . 
     FIG. 7 illustrates the weave repeats for a second embodiment. 
     FIG. 8 a top plan view of the embodiment shown in FIG.  7 . 
     FIG. 9 illustrates a closed seam in accordance with the present invention. 
     FIG. 10 illustrates the weave repeat for one additional thread in accordance with a third embodiment of the present invention. 
     FIG. 11 illustrates the weave repeat for a second additional thread in accordance with the third embodiment. 
     FIG. 12 shows the weave repeats of FIGS. 10 and 11 in combination. 
     FIG. 13 illustrates the weave repeat for one additional thread in accordance with a fourth embodiment of the present invention. 
     FIG. 14 illustrates the weave repeat for a second additional thread in accordance with the fourth embodiment. 
     FIG. 15 shows the weave repeats of FIGS. 13 and 14 in combination. 
     FIG. 16 illustrates the weave repeat for one additional thread in accordance with a fifth embodiment of the present invention. 
     FIG. 17 illustrates the weave repeat for a second additional thread in accordance with the fifth embodiment. 
     FIG. 18 shows the weave repeats of FIGS. 16 and 17 in combination. 
     FIG. 19 illustrates the weave repeat for one additional thread in accordance with a sixth embodiment of the present invention. 
     FIG. 20 illustrates the weave repeat for a second additional thread in accordance with the sixth embodiment. 
     FIG. 21 shows the weave repeats of FIGS. 19 and 20 in combination. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments will be described with reference to the drawing figures wherein like numerals represent like elements throughout. 
     Referring to FIG. 1, it shows a portion of the base fabric seam loops with additional threads woven in accordance with the present invention. The base fabric  1  comprises a top layer of MD threads,  10 ,  12 ,  14 ,  16 ,  18 ,  20 ,  22 , and  24 , and a bottom layer of MD threads,  11 ,  13 ,  15 ,  17 ,  19 ,  21 ,  23  and  25 . It will be understood that the top and bottom layers are essentially continuous threads which form the seam loops  35 - 1  to  35 - 8  between the top and bottom layers. Typically, the phantom CM threads  2 - 5  are interwoven with the top and bottom MD thread layers in a given repeat pattern to form the body of the fabric. The body of the fabric forms no part of the present invention. A seam zone  40  exists between the end CMD thread  2  and the seam loops  35 - 1  to  35 - 8 . 
     Reference is now made to FIGS. 3,  4  and  5 . Although some benefits will be obtained with a single thread, in the preferred embodiment two additional threads are used for more uniformity in the paper side surface. The two additional CMD threads  50  and  51  are interwoven in the seam zone  40  with both layers of MD threads  10  through  25 . Additional CMD thread  50  preferably weaves in a repeat that passes over MD threads  10 - 11 , between threads  12 - 13 , over threads  14  and  15 , between pairs of threads  16 - 17 ,  18 - 19 , under threads  20 - 21  and between pairs of threads  22 - 23 ,  24 - 25 . 
     With reference to FIG. 4, the second thread  51  is woven in a mirror image to the thread  50 . Thus, CMD thread  51  weaves in a repeat that passes between the pair of threads  10 - 11 , beneath the threads of pair  12 - 13 , between the pairs  14 - 15 ,  16 - 17 , over the threads of pair  18 - 19 , between threads  20  and  21 , over the threads of pair  22 - 23 , and between threads  24 - 25 . 
     As can be seen from FIG. 5, two threads woven in accordance with FIGS. 3 and 4 produce a weave repeat structure having two crossover points  53  and  54  which are spaced apart by at least three MD threads. It will also be noted that MD thread  16  passes over both additional threads  50  and  51 . Since the repeat pattern extends over eight pairs of MD threads with only a single interlacing in the machine side MD layer and the threads can shift beneath thread  16 , threads  50  and  51  tend to act as one. As a result of the long transition and the spaced crossovers, the threads  50  and  51  can migrate relative to each other so that the resulting sheet side MD and CMD weave repeat appears to be a plain weave. This result is illustrated in FIG. 6 where the thread migration results in what appears to be a single thread structure. 
     With reference to FIG. 7, there is shown a second embodiment in a manner similar to that of FIG.  5 . In this second embodiment, weave repeats of the CMD threads  55  and  56  result in floats over three machine direction threads  10 ,  12  and  14  and over three machine direction threads  18 ,  20 , and  22 . The long transition between pairs of machine direction threads and the interlacing with a single machine side MD thread per repeat is as previously described. This embodiment&#39;s crossover points  57  and  58  are also spaced apart by three MD threads; however, it also has two MD threads  16  and  24  that pass over, without interweaving, the intersection or crossover points of threads  55  and  56 . Thus, the threads  50  and  51  will migrate relative to each other and produce relatively large, in-line sheet side floats. FIG. 8 illustrates the migration of threads  55  and  56  in a manner similar to that described with respect to FIG.  6 . 
     FIG. 9 illustrates two ends of the fabric of the present invention joined by pintle  60 . The additional threads  55  and  56  at each end of the fabric provide increased surface contact for better batt adhesion in the seam zone. 
     A third embodiment of the present invention is shown in FIGS. 10-12. The fabric of this embodiment repeats on twenty four MD threads  10 - 33 . The two additional threads  70  and  71  are interwoven in the seam zone  40  with both layers of longitudinal threads  10  through  33 . Additional CMD thread  70  weaves in a repeat pattern that passes between MD threads  10 - 11 , under MD threads  12 - 13 , between MD thread pairs  14 - 15 ,  16 - 17 , and then weaves a continuous portion of plain weave with top layer MD threads  18 ,  20 ,  22 ,  24 ,  26 ,  28 , 30  before transitioning down between MD threads  32 - 33 . With reference to FIG. 11, the second additional thread  71  is woven in a complementary pattern to that of thread  70 . Additional thread  71  weaves a plain weave construction with top layer threads  10 ,  12 ,  14  before transitioning into a mid-plane float between MD thread pairs  16 - 17 ,  18 - 19  ,  20 - 21  ,  22 - 23 , weaving under MD threads  24 - 25  and transitioning back to a mid-plane float beneath thread pairs  26 - 27 ,  28 - 29 ,  30 - 31 ,  32 - 33 . 
     As can be seen from FIG. 12, two additional threads interwoven in accordance with FIGS. 10 and 11 produce a weave repeat structure having the appearance of a plain weave in the upper layer and two crossover points  73  and  74  which are spaced apart by at least three MD thread pairs. This results from the additional longitudinal thread being in a continuous portion  80  of the weave repeat with seven adjacent MD threads between transitions from the machine or paper side longitudinal threads. Since the repeat pattern extends over twelve pairs of MD threads with only a single interlacing in the machine side MD layer and spaced apart crossover points, the additional threads can shift relative to each other and threads  70  and  71  tend to act as one thread in a continuous plain weave on the top layer. As a result of the long transitions, the interlacing patterns and the spaced crossover points, the additional threads can migrate relative to each other to produce the desired sheet side weave pattern while also providing mid-plane floats and long transitions. 
     With reference to FIGS. 13-15, there is shown a fourth embodiment of the present invention. In this fourth embodiment, the first additional thread  75  weaves between MD thread pairs  10 - 11 ,  12 - 13 , beneath MD threads  14 - 15 , between MD thread pairs  16 - 17 ,  18 - 19 ,  20 - 21 , and then in a plain weave repeat with the upper layer MD threads  24 ,  26 ,  28 ,  30 ,  32 . The second additional thread  76  weaves in the mirror image of thread  75 . As shown by FIG. 15, the threads  75  and  76  produce a plain weave pattern on the paper sheet side, relatively long transitions which combine to simulate a mid-plane float and cross over points  77 ,  78  which are spaced by five MD thread pairs. This encourages migration of the threads  75 ,  76  relative to each other. As with the prior embodiment, this embodiment provides a continuous portion  81  of the weave repeat that extends over at least five adjacent paper side longitudinal threads between transitions from the machine or paper side longitudinal threads. 
     Referring to FIGS. 16-18, a fifth embodiment is shown. Additional CMD thread  100  weaves in a repeat pattern that passes between MD threads  10 - 11 , under MD threads  12 - 13 , between MD thread pairs  14 - 15 ,  16 - 17 , floats over MD threads  18 - 23 , between MD threads  24 - 25 , floats over MD threads  26 - 31  and between MD threads  32 - 33 . With reference to FIG. 17, the second additional thread  101  is woven in a complementary weave pattern to that of thread  100 . Additional thread  101  weaves over MD threads  10 - 15 , between MD thread pairs  16 - 17 ,  18 - 19 ,  20 - 21 ,  22 - 23 , under MD threads  24 - 25  and between MD thread pairs  26 - 27 ,  28 - 29 ,  30 - 31 ,  32 - 33 . It will be noted from FIG. 17 that additional thread  101  forms two mid-plane floats between four pairs of MD threads  16 - 17 ,  18 - 19 ,  20 - 21 ,  22 - 23  and  26 - 27 ,  28 - 29 ,  30 - 31 ,  32 - 33 . 
     As can be seen from FIG. 18, the two additional threads  100 ,  101  as interwoven in FIGS. 16 and 17 produce a weave repeat structure having the appearance of an over three, under one repeat in the upper layer. The two crossover points,  103 ,  104  are spaced apart by at least three MD thread pairs. This creates a long continuous portion of the second additional thread  101  which generally forms mid-plane floats that complement the long transition of the first additional thread  100 . Since the repeat pattern extends over twelve pairs of MD threads with only a single interlacing in the machine side MD layer and spaced apart crossover points, and the additional threads can shift relative to each other and threads  100  and  101  tend to act as one thread in a continuous over three, under one weave pattern on the top layer. With reference again to FIG.  16  and additional thread  100 , it can be seen that the weave repeat of thread  100  includes a subrepeat of three over one under which repeats twice within the pattern. This weave repeat permits the relatively loose interlacing of the thread  101  but enables the pattern to be continued throughout the upper layer when the threads  100 ,  101  are combined in accordance with FIG.  18 . 
     With reference to FIGS. 19-21, there is shown a sixth embodiment of the present invention. In this sixth embodiment, the first additional thread  105  weaves between MD thread pairs  10 - 11 ,  12 - 13 , beneath MD threads  14 - 15 , between MD thread pairs  16 - 17 ,  18 - 19 ,  20 - 21 , and then in two repeats of the subrepeat pattern of over two, under one with upper MD threads  22 ,  24 ,  26 ,  28 ,  30 ,  32 . 
     The second additional thread  106  weaves in the mirror image of thread  105 . As shown by FIG. 21, the threads  105  and  106  produce a two over, one under weave pattern on the paper sheet side, relatively long transitions which combine to simulate continuous floats in the mid-plane and crossover points  107 , 108  which are spaced apart by five MD thread pairs. This encourages migration of the threads relative to each other. As with the prior embodiment, this embodiment provides a weave repeat that includes two repeats of the subrepeat in adjacent paper side longitudinal threads between the transitions from the machine or paper side longitudinal threads. 
     It will be appreciated that batt adhesion will be most improved on the sheet side surface but that some improvement in machine side surface adhesion will result from the presence of the interlacings and relatively long transitions. 
     The additional CMD threads  50 ,  51 ;  55 ,  56 ;  70 ,  71 ;  75 ,  76 ;  100 ,  101 ; and  105 ,  106  can be multifilament, spun, braided, knitted, or bicomponent. If the thread is of a bicomponent nature, the bicomponent material may have a core material with a higher melting point surrounded by a covering of a lower melting point material. This allows the covering to melt and adhere to the batt material during finishing without affecting the core structure of the thread. Threads may be made from polymeric resins selected from a group consisting of polyamide, polyurethanes, polyesters, polyaramids, polyimides, polyolefins, polyetherketones, polypropylenes, PET, PBT, PTT, phenolics, and copolymers thereof.