Multi-layered papermaker's seam product with formed loops

An endless woven papermaker's fabric of having warp yarns in at least two layers and continuous weft yarns in at least two layers. The warp and weft yarns are interwoven to form a fabric where the first warp yarn layer is adjacent to the second warp layer and the weft yarns define seam loops at two ends of the fabric. Each end of the fabric has at least one warp yarn which is free of interweaving with the weft yarns and is removed to form the seam loops.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to a woven fabric which is designed 
for use in a paper, cellulose or board manufacturing machine, and which 
along each end, has a plurality of loops to be included in a seam to form 
an endless woven fabric. The invention also relates to a method of 
manufacturing such a fabric. 
2. Description of the Prior Art 
Seamed papermaking fabrics have seams that allow the fabric to be assembled 
and disassembled on a papermaking machine without the requirement of 
stitching or weaving. Prior art seamed fabrics can be divided into two 
basic categories, the first having seams formed outside of the weaving 
loom and the second having seams formed in the weaving loom. 
The first category of fabrics, those having seams formed outside the 
weaving loom, includes flat woven fabrics with an independent seam 
structure attached to the ends of the fabric, such as by sewing a woven 
tape onto the fabric or piercing it with clipper hooks. These structures 
have provided poor caliper and density profiles in the seam area. Other 
structures, such as described in U.S. Pat. No. 4,244,084, are formed with 
an area free of cross direction yarns near each end of the fabric. Loops 
are formed by folding each end of the fabric back along itself and then 
stitching each end to hold the folded ends. This structure again provides 
poor caliper and density profiles in the seam area due to the fold back 
thickness, and has a strength and life which is limited to the strength of 
the stitching holding the folded fabric. These problems have effectively 
precluded the successful use of any of these types of fabric seams in the 
wet press section of papermaking machines. Seam loops have also been 
formed on flat woven fabrics by tying back machine direction yarns at each 
end of the fabric. However, tying back is generally a time consuming 
process which must be performed after the fabric is woven. 
In the second category, in which a pin seam is formed during the weaving 
process on the loom, a conventional approach for forming such seam loops 
is shown in U.S. Pat. No. 3,815,645. In that process, pairs of weft yarns 
are woven around a forming wire to form the loops and then the forming 
wire is removed. Seam loops formed by this process are often difficult to 
mesh together because of their inconsistent sizes, shapes and orientations 
which result from the weaving method. In addition, when the forming wire 
is removed, the resultant fabric is generally a flat fabric with loop ends 
at each end thereof. Along the length of the fabric, the warp yarns weave 
with both layers of weft yarns, thereby joining the two weft yarns 
together. 
Accordingly, there exists a need for a base fabric having seam loops which 
provide better fabric properties in the seam area while being easier to 
make and install. 
SUMMARY OF THE INVENTION 
The present invention relates to an endless woven papermaker's fabric of a 
type having warp yarns in at least two layers and continuous weft yarns in 
at least two layers. The warp and weft yarns are interwoven to form a 
fabric where the first warp yarn layer is adjacent to the second warp 
layer and the weft yarns define seam loops at two ends of the fabric. Each 
end of the fabric has at least one warp yarn which is free of interweaving 
with the weft yarns and is removed to form the seam loops.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention will be described with reference to the drawing 
figures where like numerals represent like elements throughout. 
Referring to FIGS. 1 and 2, the preferred embodiment of the base fabric 10 
of the present invention is shown. The preferred base fabric 10 generally 
comprises weft yarns 12 that form two layers which are interwoven with two 
layers of warp yarns 14 as an endless woven fabric. Seam loops 17, 19 are 
formed at each end of the base fabric 10 by the absence of warp yarns 14b 
from areas at each end of the fabric 10. Each warp free area 16, 18 has an 
area of substantially uncrimped weft yarns 12 which form the seam loops 
17, 19. 
Although the warp yarns 14b may be interwoven with the weft yarns 12, it is 
preferred that those warp yarns 14b are not interwoven. Instead, the 
appropriate heddles are maintained in a stationary position during 
weaving, and therefore, do not move warp yarns 14b up and down to 
interweave with the weft yarns 12. As a result, all of the weft yarns 12 
weave about only one side of each warp yarn 14b. The warp yarns 14b are 
easily removed from the woven base fabric 10 before any finishing 
processes to form the warp free areas 16, 18. As a result of the warp free 
areas 16, 18, the seam loops 17, 19 remain substantially uncrimped after 
heat setting. The warp free areas 16, 18 are preferably, but do not have 
to be, formed on the loom edges. In applications in which the warp free 
areas 16, 18 are not formed on the loom edges, the seam loops 17, 19 can 
be aligned at the ends of fabric 10 after the fabric 10 is removed from 
the loom. The length of the seam loops 17, 19 can be varied depending on 
the requirements of a particular application. 
To seam the fabric 10 on a papermaking machine, the ends of the fabric 10 
are brought toward each other as shown in FIG. 2. The seam loops 17, 19 
are intermeshed and a pintle 20 is inserted therethrough to join the 
fabric 10, as shown in FIG. 3. Other joining methods known in the art may 
also be utilized. For example, coil type loops may be inserted between the 
loop seams 17, 19. A layer of batt material 30 may be applied to one or 
both sides of the base fabric 10 as desired. 
If a particular application requires a more dense fabric, stuffer yarns may 
be inserted between the layers of the base fabric 10. If a longer machine 
direction fabric is desired, the base fabric 10 can be produced using 
known endless fabric weaving methods. In such a fabric, the warp free 
areas 16, 18 will exist on opposite ends of the fabric once the edges of 
the fabric are extended in the machine direction. 
While the present invention has been described in terms of the preferred 
embodiments, other variations which are within the scope of the invention 
as outlined in the claims will be apparent to those skilled in the art.