[0001] The present invention relates to papermakers fabrics and in particular to fabrics
comprised of flat monofilament yarns.
BACKGROUND OF THE INVENTION
[0002] Papermaking machines generally are comprised of three sections: forming, pressing,
and drying. Papermakers fabrics are employed to transport a continuous paper sheet
through the papermaking equipment as the paper is being manufactured. The requirements
and desirable characteristics of papermakers fabrics vary in accordance with the particular
section of the machine where the respective fabrics are utilized.
[0003] With the development of synthetic yarns, shaped monofilament yarns have been employed
in the construction of papermakers fabrics. For example, U.S. Patent No. 4,290,209
discloses a fabric woven of flat monofilament warp yarns; U.S. Patent No. 4,755,420
discloses a non-woven construction where the papermakers fabric is comprised of spirals
made from flat monofilament yarns.
[0004] Numerous weaves are known in the art which are employed to achieve different results.
For example, U.S. Patent No. 4,438,788 discloses a dryer fabric having three layers
of cross machine direction yarns interwoven with a system of flat monofilament machine
direction yarns such that floats are created on both the top and bottom surfaces of
the fabric. The floats tend to provide a smooth surface for the fabric.
[0005] Permeability is an important criteria in the design of papermakers fabrics. In particular,
with respect to fabrics made for running at high speeds on modern drying equipment,
it is desirable to provide dryer fabrics with relatively low permeability.
[0006] U.S. Patent No. 4,290,209 discloses the use of flat monofilament warp yarns woven
contiguous with each other to provide a fabric with reduced permeability. However,
even where flat warp yarns are woven contiguous with each other, additional means,
such as stuffer yarns, are required to reduce the permeability of the fabric. As pointed
out in that patent, it is desirable to avoid the use of fluffy, bulky stuffer yarns
to reduce permeability which make the fabric susceptible to picking up foreign substances
or retaining water.
[0007] U.S. Patent No. 4,290,209 and U.S. Patent No. 4,755,420 note practical limitations
in the aspect ratio (cross-sectional width to height ratio) of machine direction warp
yarns defining the structural weave of a fabric. The highest practical aspect ratio
disclosed in those patents is 3:1, and the aspect ratio is preferably, less than 2:1.
[0008] U.S. Patent No. 4,621,663, assigned to the assignee of the present invention, discloses
one attempt to utilize high aspect ratio yarns (on the order of 5:1 and above) to
define the surface of a papermakers dryer fabric. As disclosed in that patent, a woven
base fabric is provided to support the high aspect ratio surface yarns. The woven
base fabric is comprised of conventional round yarns and provides structural support
and stability to the fabric disclosed in that patent.
[0009] U.S. Patent No. 4,815,499 discloses the use of flat yarns in the context of a forming
fabric. That patent discloses a composite fabric comprised of an upper fabric and
a lower fabric tied together by binder yarns. The aspect ratio employed for the flat
machine direction yarns in both the upper and lower fabrics are well under 3:1.
[0010] In use, papermakers fabrics are configured as endless belts. Weaving techniques are
available to initially weave fabrics endless. However, there are practical limitations
on the overall size of endless woven fabrics as well as inherent installation difficulties.
Moreover, not all papermaking equipment is designed to accept the installation of
an endless fabric.
[0011] Flat woven fabrics are often supplied having opposing ends which are seamed together
during installation of the fabric on papermaking equipment. Usually one end of the
fabric is threaded through the serpentine path defined by the papermaking equipment
and is then joined to its opposing end to form a continuous belt.
[0012] A variety of seaming techniques are well known in the art. One conventional method
of seaming is to form the machine direction yarns on each end of the fabric into a
series of loops. The loops of the respective fabric ends are then intermeshed during
fabric installation to define a channel through which a pintle is inserted to lock
the ends together.
[0013] For example, U.S. Patent Nos. 4,026,331; 4,438,789; 4,469,142; 4,846,231; 4,824,525
and 4,883,096 disclose a variety of pin seams wherein the machine direction yarns
are utilized to form the end loops. In each of those patents, however, the machine
direction yarn projects from the end of the fabric and weaves back into the fabric
adjacent to itself. Accordingly, the loops inherently have a twist or torque factor
and are not entirely orthogonal to the plane of the fabric. U.S. Patent 4,883,096
specifically addresses this problem.
[0014] It would be desirable to provide a papermakers fabric with machine direction seaming
loops which do not have torque and/or twist.
SUMMARY AND OBJECTS INVENTION
[0015] The present invention provides a papermakers fabric having a system of flat monofilament
machine direction yarns (hereinafter MD yarns) which are stacked to control the permeability
of the fabric. The present weave also provides for usage of high aspect ratio yarns
as structural weave components. The system of MD yarns comprises upper and lower yarns
which are vertically stacked. Preferably, the upper MD yarns define floats on the
upper surface of the fabric and each upper MD yarn is paired in a vertically stacked
orientation with a lower MD yarn. The lower MD yarns may weave in an inverted image
of the upper MD yarns to provide floats on the bottom fabric surface or may weave
with a different repeat to provide a different surface on the bottom of the fabric.
[0016] At least the upper MD yarns are flat monofilament yarns woven contiguous with each
other to reduce the permeability of the fabric and to lock in the machine direction
alignment of the stacking pairs of MD yarns. In the preferred embodiment, the same
type and size yarns are used throughout the machine direction yarn system and both
the top and the bottom MD yarns weave contiguously with adjacent top and bottom MD
yarns, respectively. The stacked, contiguous woven machine direction system provides
stability and permits the MD yarns to have a relatively high aspect ratio, cross-sectional
width to height, of greater than 3:1.; the aspect ratio preferably ranging from about
2:1 to 6:1. machine direction yarns further define a series of orthogonal seaming
loops on the opposing fabric ends. End segments of the lower MD yarns are removed
and the upper MD yarn ends are looped back upon themselves and rewoven into the fabric
end in the space vacated by the trimmed lower MD yarn end segments. The lower MD yarns
may weave in an inverted image of the upper MD yarns such that the crimp of the upper
MD yarns conforms with the lower MD yarn weave pattern space into which the upper
MD yarn ends are backwoven. This improves the strength of the seam.
[0017] Non-loop forming upper MD yarns are also preferably backwoven into the space vacated
by trimming the respective lower MD yarns. Preferably, at least the upper MD yarns
are woven contiguous with each other to lock in the machine direction alignment of
the stacking pairs of MD yarns and the orthogonal orientation of the end loops. In
the preferred embodiment, the same type of material and the same geometric shape and
size yarns are used throughout the machine direction yarn system and both the top
and the bottom MD yarns weave contiguously with adjacent top and bottom MD yarns,
respectively.
[0018] It is an object of the invention to provide a papermakers fabrics having permeability
controlled with woven flat machine direction yarns.
[0019] It is a further object of the invention to provide a low permeability fabric constructed
of all monofilament yarns without the use of bulky stuffer yarns and without sacrificing
strength or stability.
[0020] Other objects and advantages will become apparent from the following description
of presently preferred embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[0021]
Figure 1 is a schematic diagram of a papermakers fabric made in accordance with the
teachings of the present invention;
Figure 2 is a cross-sectional view of the fabric depicted in Figure 1 along line 2-2;
Figure 3a is a cross-sectional view of the fabric depicted in Figure 1 along line
3-3;
Figure 3b is a cross-sectional view of a prior art weave construction;
Figure 4a illustrates the yarn orientation in the fabric depicted in Figure 1 after
the fabric is finished showing only two representative stacked MD yarns;
Figures 4b, 4c, and 4d are a series of illustrations showing the formation of a seaming
loop for the papermakers fabric depicted in Figure 1;
Figure 5a is a perspective view of a prior art MD yarn seaming loop;
Figure 5b is a perspective view of an orthogonal MD yarn seaming loop made in accordance
with the present invention;
Figure 6 is a schematic view of a second embodiment of a fabric made in accordance
with the present invention;
Figure 7 is a cross-sectional view of the fabric depicted in Figure 6 along line 7-7;
Figure 8 is a cross-sectional view of the fabric depicted in Figure 6 along line 8-8;
Figure 9 is a perspective view of a portion of the fabric illustrated in Figures 6-8;
Figure 10 illustrates the yarn orientation in the finished fabric depicted in Figure
6 showing the end loop formed by one of the MD yarns;
Figure 11 is a top view of the opposing ends of a fabric constructed in accordance
with Figure 6 just prior to pin-seaming the ends together;
Figure 12 is a schematic view of a third alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns;
Figure 13 is a schematic view of a fourth alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns;
Figure 14 is a schematic view of a fifth alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns;
Figure 15 is a schematic view of a sixth alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns;
Figure 16 is a schematic view of a seventh alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns; and
Figure 17 is a schematic view of a eighth alternate embodiment of a fabric made in
accordance with the teachings of the present invention showing only one pair of stacked
MD yarns.
DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS
[0022] Referring to Figures 1, 2, and 3a, there is shown a papermakers dryer fabric 10 comprising
upper, middle and lower layers of cross machine direction (hereinafter CMD) yarns
11, 12, 13, respectively, interwoven with a system of MD yarns 14-19 which sequentially
weave in a selected repeat pattern. The MD yarn system comprises upper MD yarns 14,
16, 18 which interweave with CMD yarns 11, 12 and lower MD yarns 15, 17, 19 which
interweave with CMD yarns 12, 13.
[0023] The upper MD yarns 14, 16, 18 define floats on the top surface of the fabric 10 by
weaving over two upper layer CMD yarns 11 dropping into the fabric to weave in an
interior knuckle under one middle layer CMD yarn 12 and under one CMD yarn 11 and
thereafter rising to the surface of the fabric to continue the repeat of the yarn.
The floats over upper layer CMD yarns 11 of upper MD yarns 14, 16, 18 are staggered
so that all of the upper and middle layer CMD yarns 11, 12 are maintained in the weave.
[0024] As will be recognized by those skilled in the art, the disclosed weave pattern with
respect to Figures 1, 2, and 3a, results in the top surface of the fabric having a
twill pattern. Although the two-float twill pattern represented in Figures 1, 2, and
3a is a preferred embodiment, it will be recognized by those of ordinary skill in
the art that the length of the float, the number of MD yarns in the repeat, and the
ordering of the MD yarns may be selected as desired so that other patterns, twill
or non-twill, are produced.
[0025] As best seen in Figures 2 and 3a, lower MD yarns 15, 17, 19, weave directly beneath
upper MD yarns 14, 16, 18, respectively, in a vertically stacked relationship. The
lower yarns weave in an inverted image of their respective upper yarns. Each lower
MD yarn 15, 17, 19 floats under two lower layer CMD yarns 13, rises into the fabric
over one CMD yarn 13 and forms a knuckle around one middle layer CMD yarn 12 whereafter
the yarn returns to the lower fabric surface to continue its repeat floating under
the next two lower layer CMD yarns 13.
[0026] With respect to each pair of stacked yarns, the interior knuckle, formed around the
middle layer CMD yarns 12 by one MD yarn, is hidden by the float of the other MD yarn.
For example, in Figures 1 and 3a, lower MD yarn 15 is depicted weaving a knuckle over
CMD yarn 12 while MD yarn 14 is weaving its float over CMD yarns 11, thereby hiding
the interior knuckle of lower MD yarn 15. Likewise, with respect to Figures 1 and
3a, upper MD yarn 18 is depicted weaving a knuckle under yarn CMD yarn 12 while it
is hidden by lower MD yarn 19 as it floats under CMD yarns 13.
[0027] The upper MD yarns 14, 16, 18, are woven contiguous with respect to each other. This
maintains their respective parallel machine direction alignment and reduces permeability.
Such close weaving of machine direction yarns is known in the art as 100% warp fill
as explained in U.S. Patent No. 4,290,209. As taught therein (and used herein), actual
warp count in a woven fabric may vary between about 80%-125% in a single layer and
still be considered 100% warp fill.
[0028] The crowding of MD yarns 14, 16, and 18 also serves to force MD yarns 15, 17, 19,
into their stacked position beneath respective MD yarns 14, 16, 18. Preferably MD
yarns 15, 17, and 19 are the same size as MD yarns 14, 16, and 18 so that they are
likewise woven 100% warp fill. This results in the overall fabric of the preferred
embodiment having 200% warp fill of MD yarns.
[0029] Since the lower MD yarns 15, 17, 19 are also preferably woven 100% warp fill, they
likewise have the effect of maintaining the upper MD yarns 14, 16, 18 in stacked relationship
with the respect to lower MD yarns 15, 17, 19. Accordingly, the respective MD yarn
pairs 14 and 15, 16 and 17, 18 and 19 are doubly locked into position thereby enhancing
the stability of the fabric.
[0030] As set forth in the U.S. Patent No. 4,290,209, it has been recognized that machine
direction flat yarns will weave in closer contact around cross machine direction yarns
than round yarns. However, a 3:1 aspect ratio was viewed as a practical limit for
such woven yarns in order to preserve overall fabric stability. The present stacked
MD yarn system preserves the stability and machine direction strength of the fabric
and enables the usage of yarns with increased aspect ratio, in a preferred range of
2:1 to 6:1, to more effectively control permeability.
[0031] The high aspect ratio of the MD yarns translates into reduced permeability. High
aspect ratio yarns are wider and thinner than conventional flat yarns which have aspect
ratios less than 3:1 and the same cross-sectional area. Equal cross-sectional area
means that comparable yarns have substantially the same linear strength. The greater
width of the high aspect ratio yarns translates into fewer interstices over the width
of the fabric than with conventional yarns so that fewer openings exist in the fabric
through which fluids may flow. The relative thinness of the high aspect ratio yarns
enables the flat MD yarns to more efficiently cradle, i.e. brace, the cross machine
direction yarns to reduce the size of the interstices between machine direction and
cross machine direction yarns.
[0032] For example, as illustrated in Figure 3b, a fabric woven with a single layer system
of a flat machine direction warp having a cross-sectional width of 1.5 units and a
cross-sectional height of 1 unit, i.e. an aspect ratio of 1.5:1, is shown. Such fabric
could be replaced by a fabric having the present dual stacked MD yarn system with
MD yarns which are twice the width, i.e. 3 units, and half the height, i.e. 0.5 units.
Such MD yarns thusly having a fourfold greater aspect ratio of 6:1, as illustrated
in Figure 3a.
[0033] The thinner, wider MD yarns more efficiently control permeability while the machine
direction strength of the fabric remains essentially unaltered since the cross-sectional
area of the MD yarns over the width of the fabric remains the same. For the above
example, illustrated by Figures 3a and 3b, the conventional single MD yarn system
fabric has six conventional contiguous flat yarns over 9 units of the fabric width
having a cross-sectional area of 9 square units, i.e.

. The thinner, wider high aspect ratio yarns, woven as contiguous stacked MD yarns,
define a fabric which has three stacked pairs of MD yarns over 9 units of fabric width.
Thus such fabric also has a cross-sectional area of 9 square units, i.e.

, over 9 units of fabric width.
[0034] In one example, a fabric was woven in accordance with Figures 1, 2 and 3, wherein
the CMD yarns 11, 12, 13 were polyester monofilament yarns 0.6mm in diameter interwoven
with MD yarns 14-19 which were flat polyester monofilament yarns having a width of
1.12mm and a height of 0.2mm. Accordingly, the aspect ratio of the flat MD yarns was
5.6:1. The fabric was woven at 48 warp ends per inch with a loom tension of 40 PLI
(pounds per linear inch) and 12.5 CMD pick yarns per inch per layer (three layers).
[0035] The fabric was heat set in a conventional heat setting apparatus under conditions
of temperature, tension and time within known ranges for polyester monofilament yarns.
For example, conventional polyester fabrics are heat set within parameters of 340°F-380°F
temperature, 6-15 PLI (pounds per linear inch) tension, and 3-4 minutes time. However,
due to their stable structure, the fabrics of the present invention are more tolerant
to variations in heat setting parameters.
[0036] The fabric exhibited a warp modulus of 6000 PSI (pounds per square inch) measured
by the ASTM D-1682-64 standard of the American Society for Testing and Materials.
The fabric stretched less that 0.2% in length during heat setting. This result renders
the manufacture of fabrics in accordance with the teachings of the present invention
very reliable in achieving desired dimensional characteristic as compared to conventional
fabrics.
[0037] The resultant heat set fabric had 12.5 CMD yarns per inch per layer with 106% MD
warp fill with respect to both upper and lower MD yarns resulting in 212% actual warp
fill for the fabric. The finished fabric has a permeability of 83CFM as measured by
the ASTM D-737-75 standard.
[0038] As illustrated in Figure 4a, when the fabric 10 is woven the three layers of CMD
yarns 11, 12, 13 become compressed. This compression along with the relatively thin
dimension of the MD yarns reduces the caliper of the fabric. Accordingly, the overall
caliper of the fabric can be maintained relatively low and not significantly greater
than conventional fabrics woven without stacked MD yarn pairs. In the above example,
the caliper of the finished fabric was 0.050 inches.
[0039] It will be recognized by those of ordinary skill in the art that if either top MD
yarns 14, 16, 18 or bottom MD yarns 15, 17, 19 are woven at 100% warp fill, the overall
warp fill for the stacked fabric will be significantly greater than 100% which will
contribute to the reduction of permeability of the fabric. The instant fabric having
stacked MD yarns will be recognized as having a significantly greater percentage of
a warp fill than fabrics which have an actual warp fill of 125% of non-stacked MD
yarns brought about by crowding and lateral undulation of the warp strands. Although
the 200% warp fill is preferred, a fabric may be woven having 100% fill for either
the upper or lower MD yarns with a lesser degree of fill for the other MD yarns by
utilizing yarns which are not as wide as those MD yarns woven at 100% warp fill. For
example, upper yarns 14, 16, 18 could be 1 unit wide with lower layer yarns 15, 17,
19 being .75 units wide which would result in a fabric having approximately 175% warp
fill.
[0040] Such variations can be used to achieve a selected degree of permeability. Alternatively,
such variations could be employed to make a forming fabric. In such a case, the lower
MD yarns would be woven 100% warp fill to define the machine side of the fabric and
the upper MD yarns would be woven at a substantially lower percentage of fill to provide
a more open paper forming surface.
[0041] The stacked pair MD weave permits the formation of orthogonal seaming loops within
MD yarns. With reference to Figures 4a-d, after the fabric has been woven and heat
set (Figure 4a), CMD yarns are removed leaving the crimped MD yarns 14, 15 exposed
(Figure 4b). One of the yarns, for example, MD lower yarn 15, of the stacked pair
is trimmed back a selected distance leaving the other exposed MD yarn 14 of the MD
yarn pair and vacated space between the CMD yarns, as illustrated in Figure 4c. Upper
MD yarn 14 is then backwoven into the space vacated in the weave pattern by lower
MD yarn 15 such that a loop L is formed on the end of the fabric, as illustrated in
Figure 4d. Preferably, between 0.5 - 5.0 inches of upper layer yarn 14 is backwoven
into the fabric to provide sufficient strength for the end loop and assure retention
of the free end of MD yarn 14 within the weave of the fabric. The inverted image weave
permits the crimp of the upper MD yarn 14 to match the space vacated by the lower
MD yarn 15 which further enhances the strength of the end loop.
[0042] As shown in phantom in Figure 4d, adjacent yarn pair 16, 17 is processed in a similar
manner. However, when upper yarn 16 is looped back and backwoven in the fabric, it
is pulled against the CMD yarns. In the preferred embodiment, wherein the upper MD
yarns are woven 100% fill, the crowding of the yarns secure the orthogonal orientation
of the seaming loops.
[0043] To achieve a uniform seam for a fabric woven in accordance with the weave pattern
depicted in Figure 1, each upper MD yarn 14 forms a loop and the other upper MD yarns
16, 18 are backwoven against the endmost CMD yarn of the fabric. Thus every third
upper MD yarn defines a loop such that an array of loops is created on each end of
the fabric. The seam is assembled by intermeshing the opposing arrays of loops and
inserting a pintle yarn between the intermeshed loops.
[0044] Preferably, loop forming yarns 14 would all be backwoven approximately the same distance
within the fabric to provide sufficient strength to prevent the loops from being pulled
apart during normal usage. Non-loop forming yarns 16, 18, would preferably be backwoven
a somewhat shorter distance since during usage no load is imparted to those yarns.
For example, upper MD yarns 14 would be backwoven approximately 3 inches, MD yarns
16 would be backwoven approximately 2 inches, and MD yarns 18 would be backwoven approximately
1 inch. Respective lower layer yarns 15, 17, 19 would be trimmed to complement the
backweaving of their respective MD yarn pair yarns 14, 16, 18.
[0045] Figures 5a and 5b, respectively, illustrate a conventional seaming loop 50 in comparison
with an orthogonal seaming loop L of the present invention. In conventional loop forming
techniques, the MD yarn 51 is backwoven into the fabric adjacent to itself thereby
inherently imparting twist and/or torque to the loop structure 50. In the present
invention, the MD yarn is looped directly beneath itself and does not have any lateral
offset which would impart such twist or torque to the seaming loop.
[0046] Referring to Figures 6, 7 and 8, there is shown a second preferred embodiment of
a fabric 20 made in accordance with the teachings of the present invention. Papermakers
fabric 20 is comprised of a single layer of CMD yarns 21a, 21b interwoven with a system
of stacked MD yarns 22-25 which weave in a selected repeat pattern. The MD yarn system
comprises upper MD yarns 22, 24 which define floats on the top surface of the fabric
20 by weaving over three CMD yarns, under the next one CMD yarn 21a to form a knuckle,
and thereafter returning to float over the next three CMD yarns in a continuation
of the repeat.
[0047] Lower MD yarns 23, 25, weave directly beneath respective upper MD yarns 22, 24 in
a vertically stacked relationship. The lower MD yarns weave in an inverted image of
their respective upper MD yarns. Each lower MD yarn 23, 25 floats under three CMD
yarns, weaves upwardly around the next one CMD yarn 21a forming a knuckle and thereafter
continues in the repeat to float under the next three CMD yarns.
[0048] As can be seen with respect to Figures 6 and 8, the knuckles formed by the lower
MD yarns 23, 25 are hidden by the floats defined by the upper MD yarns 22, 24 respectively.
Likewise the knuckles formed by the upper MD yarns 22, 24 are hidden by the floats
of the lower MD yarns 23, 25 respectively.
[0049] The caliper of the fabric proximate the knuckle area shown in Figure 8, has a tendency
to be somewhat greater than the caliper of the fabric at non-knuckle CMD yarns 21b,
shown in Figure 7. However, the CMD yarns 21a around which the knuckles are formed
become crimped which reduces the caliper of the fabric in that area as illustrated
in Figure 8. Additionally, slightly larger diameter CMD yarns are preferably used
for CMD yarns 21b, shown in Figure 7, which are not woven around as knuckles by the
MD yarns to eliminate any difference in fabric caliber. Preferably the diameter of
the larger CMD yarn 21b equals the diameter d of the smaller CMD yarns 21a plus the
thickness t of the MD yarns.
[0050] In one example, a fabric was woven in accordance with Figures 6-9, wherein the CMD
yarns 21a, 21b were polyester monofilament yarns 0.6mm and 0.8mm, respectively, in
diameter interwoven with MD yarns 22-25 which were flat polyester monofilament yarns
having a width of 1.12mm and a height of 0.2mm. Accordingly, the aspect ratio of the
flat MD yarns was 5.6:1. The fabric was woven at 48 total warp ends per inch with
a loom tension of 40 PLI (pounds per linear inch) and 20 CMD total pick yarns per
inch. The permeability averaged 90 CFM in the resultant fabric.
[0051] In another example, fabric was woven in accordance with Figures 6, 7 and 8, wherein
the CMD yarns 21a, 21b were polyester monofilament yarns 0.7mm in diameter interwoven
with MD yarns 22-25 which were flat polyester monofilament yarns having a width of
1.12mm and a height of 0.2mm. Accordingly, the aspect ratio of the flat MD yarns was
5.6:1. The fabric was woven at 22 CMD pick yarns per inch. The fabric was heat set
using conventional methods. The fabric exhibited a modulus of 6000 PSI. The fabric
stretched less than 0.2% in length during heat setting. The resultant fabric had 22
CMD yarns per inch with 106% MD warp fill with respect to both upper and lower MD
yarns resulting in 212% actual warp fill for the fabric. The finished fabric had a
caliper of .048 inches and an air permeability of 60CFM.
[0052] As best shown in Figure 9, the high aspect ratio yarns 22-24 effectively brace the
CMD yarns 21a in the weave construction. This bracing effect can be quantified in
terms of the degree of contact arc ϑ and contact bracing area, CBA, as follows:

where
- d =
- diameter of the CMD yarn
- ϑ =
- the degree of arc over which there is contact between the MD and CMD yarns
- w =
- width of the MD yarn
- π =
- the constant pi.
[0053] The degrees of arc over which MD yarns 22-25 are in contact with CMD yarns 21a is
dependent upon the spacing of the CMD yarns within the weave. For the above example,
employing alternating 0.6mm and 0.8mm diameter CMD yarns with 0.2mm thick MD yarns,
the degree of contact arc can be maintained in a preferred range of between 60° to
180° by varying the pick count of the CMD yarns from 14 picks per inch to a maximum
of 28.22 picks per inch.
[0054] In the preferred embodiment where the pick count is 20 picks per inch, the degree
of contact arc ϑ is approximately 101°. This results in a bracing contact area of
approximately 0.79mm² at each knuckle in the fabric.
[0055] Applicant's use of high ratio aspect yarns, i.e. yarns having a width:thickness ratio
of at least 3:1, provides for increased bracing contact of the flat MD yarns with
the CMD yarns 21a. This is comparatively exemplified by modifying the equation for
contact bracing area, CBA, to be defined in terms of the thickness of the MD yarns.
[0056] Since the MD yarn width w equals the thickness t of the MD yarn multiplied by the
aspect ratio, w > 3t for yarns having an aspect ratio greater than 3:1. Accordingly,
fabrics made in accordance with the teachings of the present invention utilizing high
aspect ratio MD yarns exhibit enhanced bracing of the CMD yarns by the MD yarns such
that:

[0057] As best seen in Figure 10, seaming loops are formed by upper MD yarns 22. The respective
lower MD yarns 23 are trimmed a selected distance from the fabric end and the upper
MD yarns 22 are backwoven into the space vacated by the trimmed lower MD yarns 23.
[0058] Upper MD yarns 24 are similarly backwoven into the space vacated by trimming back
lower MD yarns 25. However, as best seen in Figure 10, upper MD yarns 24 are backwoven
against the madness CMD yarn 21b.
[0059] As illustrated in Figure 11, a series of seaming loops is formed on each of the opposing
fabric ends 27, 28. When the fabric is installed on papermaking equipment, the respective
end loops formed by MD yarns 22 are intermeshed and a pintle 30 is inserted therethrough
to lock the intermeshed series of loops together.
[0060] Since the seaming loops L are formed by backweaving MD yarns 22 directly beneath
themselves, no lateral twist or torque is imparted on the loop and the loops are orthogonal
with the plane of the fabric. This facilitates the intermeshing of the loop series
of the opposing fabric ends 27, 28. The orthogonal loops are particularly advantageous
where, as shown in Figure 10, the MD yarns 22, 24 are 100% warp fill and adjacent
loops are separated by individual MD yarns of the same width as the loop MD yarns
22. Lateral torque or twist on the seaming loops make the seaming process more difficult
particularly where the loop-receiving gaps between the loops of one fabric end are
essentially the same width as the loops on the opposing fabric end and vice versa.
[0061] With reference to the fabric depicted in Figures 6-11, the loop forming MD yarns
22 are preferably backwoven approximately 2 inches while the non-loop forming MD yarns
24 are preferably backwoven 1 inch.
[0062] With reference to Figure 12, a third embodiment of a papermakers fabric 30 is shown.
Fabric 30 comprises a single layer of CMD yarns 31 interwoven with stacked pairs of
flat monofilament yarns in a selected repeat pattern. For clarity, only one pair of
stacked MD yarns is shown comprising upper MD yarn 32 and lower MD yarn 33. The upper
MD yarns weave in a float over two CMD yarns 31, form a single knuckle under the next
CMD yarn 31 and thereafter repeat. Similarly the lower MD yarns weave in an inverted
image of the upper MD yarns weaving under two CMD yarns 31, forming a knuckle over
the next CMD yarn 31 and then returning to the bottom surface of the fabric in the
repeat. Since the repeat of both the upper and lower MD yarns is with respect to three
CMD yarns 31, a total of three different stacked pairs of yarns comprise the weave
pattern of the MD yarn system.
[0063] A fabric was woven in accordance with Figure 12 wherein the CMD yarns 31 were polyester
monofilament yarns 0.7mm in diameter interwoven with MD yarns which were flat polyester
monofilament yarns having a width of 1.12mm and a height of 0.2mm. Accordingly, the
aspect ratio of the flat MD yarns was 5.6:1. The fabric was woven 48 warp ends per
inch under a loom tension of 60 PLI and 18 CMD pick yarns per inch. The fabric was
heat set using conventional methods. The fabric exhibited amodulus of 6000 PSI. The
fabric stretched less than 0.2% in length during heat setting. The resultant fabric
had 18 CMD yarns per inch with 106% MD warp fill with respect to both upper and lower
MD yarns resulting in 212% actual warp fill for the fabric. The finished fabric having
a caliper of 0.046 inches and an air permeability of 66CFM.
[0064] With reference to Figure 13, a fourth embodiment of a papermakers fabric 40 is shown.
Fabric 40 comprises upper, middle and lower layers of CMD yarns 41, 42, 43, respectively,
interwoven with stacked pairs of flat monofilament yarns in a selected repeat pattern.
For clarity, only one pair of stacked MD yarns is shown comprising upper MD yarn 44
and lower MD yarn 45. The upper MD yarns weave in a float over two upper layer CMD
yarns 41, under the next yarn 41 and a middle layer yarn 42 to form a single knuckle,
under the next CMD yarn 41 and thereafter rise to the top surface to continue to repeat.
Similarly, the lower MD yarns weave in an inverted image of the upper MD yarns weaving
under two lower layer CMD yarns 43 over the next CMD yarn 43 and a middle CMD yarn
42 forming a knuckle, over the next CMD yarn 43 then returning to the bottom surface
of the fabric to repeat. Since the repeat of both the upper and lower MD yarns is
with respect to four upper and lower CMD yarns 41, 43, respectively, a total of four
different stacked pairs of yarns comprise the weave pattern of the MD yarn system.
[0065] A fabric was woven in accordance with Figure 13, wherein the upper and lower layer
CMD yarns 41, 43 were nylon-sheathed, multifilament polyester yarns 0.62mm in diameter
and the middle layer CMD yarns 42 were polyester monofilament yarns 0.5mm in diameter
interwoven with MD yarns 22-25 which were flat polyester monofilament yarns having
a width of 0.60mm and a height of 0.38mm. Accordingly, the aspect ratio of the flat
MD yarns was 1.58:1. The fabric was woven with 96 warp ends per inch under a loom
tension of 40 PLI and 15 CMD pick yarns per inch per layer. The fabric was heat set
using conventional methods. The resultant fabric had 15 CMD yarns per inch per layer
with 113% MD warp fill with respect to both upper and lower MD yarns resulting in
226% actual warp fill for the fabric. The finished fabric had a caliper of .075 inches
and an air permeability of 60CFM.
[0066] Figures 14, 15 and 16 illustrate the fifth, sixth and seventh embodiments of the
present invention. Figure 14 illustrates the weave of a relatively long float on both
sides of the fabric; Figure 15 illustrates how a stacked pair MD yarn weave can define
floats of different lengths on opposite sides of the fabric; and Figure 16 illustrates
how a stacked pair MD yarn weave can be used to construct fabrics having MD knuckles
on one side of the fabric.
[0067] Relatively long floats predominating the surfaces of a dryer fabric are beneficial
for both the paper-carrying side as well as the machine side of the fabric. On the
paper-carrying side, long floats provide greater contact area with the paper sheet
for increased heat transfer. On the machine side, long floats provide increased wear
surface and contact area to reduce bounce and flutter. The stacked pair MD yarn weave
is versatile in allowing different surfaces to be defined on the top and bottom sides
of the fabric. Accordingly, fabrics made in accordance with the teachings of the present
invention may be used for other industrial purposes such as in the drying of sludge.
[0068] With respect to Figure 14, a fabric 50 is illustrated comprising three layers of
yarns 51, 52, and 53 respectively. In this construction, the MD yarn pairs, such as
the pair formed by upper layer yarn 54 and lower layer yarn 55, define relatively
long floats on both the top and bottom surfaces of the fabric. Upper yarn 54 weaves
over five upper layer CMD yarns 51, drops into the fabric to form a knuckle under
one middle layer CMD yarn 52, weaves under the next upper layer yarn 51 and thereafter
repeats. Lower MD yarn 55 weaves in an inverted image under five lower layer CMD yarns
53, rising into the fabric over the next CMD 53 to weave a knuckle over one middle
layer CMD yarn 52 thereafter dropping to the bottom surface of the fabric to continue
its repeat. In such a construction, six pairs of stacked MD yarns are utilized in
the repeat of the fabric and are sequentially woven in a selected sequence to produce
a desired pattern on the surfaces of the fabric which will be predominated by the
MD yarn floats.
[0069] The embodiment shown in Figure 15 depicts a fabric 60 in which the MD yarns weave
with a five-float repeat on the top fabric surface and a two-float repeat on the bottom
fabric surface. For example, upper MD yarn 64 interweaves with upper and middle CMD
yarns 61, 62 in the same manner that upper MD yarn 54 weaves with respective CMD yarns
51, 52 with respect to fabric 50 in Figure 14. However, lower MD yarn 65, which forms
a stacked pair with upper MD yarn 64, weaves in a two-float bottom repeat with respect
lower and middle CMD yarns 63, 62. For example, lower MD yarn 65 floats under two
lower layer CMD yarns 63, rises above the next CMD yarn 63 to form a knuckle over
one middle layer CMD yarn 62 and thereafter drops to the bottom surface of the fabric
60 to continue to repeat. As with the other embodiments discussed above, the interior
knuckles formed by the lower MD yarns are hidden by the upper MD yarn of the respective
stacked pair and vice-versa.
[0070] The construction shown in Figure 15 permits different surfaces to be defined on the
top and bottom of the fabric while utilizing the benefits of the stacked MD yarn pairing.
[0071] The embodiment shown in Figure 16 discloses another example of a fabric 70 having
five-float MD yarns predominating the upper surface of the fabric, but with MD knuckles
on the lower surface of the fabric. This type of construction may be advantageously
used to construct a forming fabric where the upper fabric surface, having relatively
long floats, would be used as the machine side of the fabric and the knuckled lower
surface of the fabric would be used as the paper forming side.
[0072] Fabric 70 includes three layers of CMD yarns 71, 72, 73 respectively which interweave
with stacked pairs of MD yarns to define this construction. Only one pair of stacked
pair of MD yarns 74, 75 is depicted for clarity. Upper MD yarn 74 weaves in a five-float
pattern with respect to upper and middle layer CMD yarns 71, 72 in the same manner
as upper MD yarn 54 with respect to fabric 50 shown in Figure 14. Lower MD yarn 75
weaves three interior knuckles and three lower surface knuckles with respect to middle
and lower layer CMD yarns 72, 73 under each upper surface float of its respective
MD yarn pair yarn 74. The repeat of the upper MD yarns is defined with respect to
six upper layer CMD yarns 71 and the repeat of the lower MD yarns is defined with
respect to only two lower layer CMD yarns 73. Accordingly, there are six different
pairs of stacked MD yarns which constitute the MD yarn system which, as noted above,
can be arranged such that a desired pattern is formed on the upper surface of the
fabric.
[0073] Generally for stacked pair weaves, the repeat of the upper MD yarns will be equally
divisible by, or an equal multiple of, the repeat of the lower MD yarns in defining
the stacking pair relationship. For example, with respect to Figure 12 the repeat
of the upper MD yarns is six upper layer CMD yarns which is equally divisible by the
repeat of the lower MD yarns which is three lower layer CMD yarns.
[0074] With respect to the eighth alternate embodiment shown in Figure 17, a fabric 80 is
illustrated having a single layer of CMD yarns 81 and a representative stacked pair
of MD yarns 82, 83. Upper MD yarn 82 weaves with two floats over CMD yarns 81 with
a repeat occurring with respect to three CMD yarns 81. Lower MD yarn 83 weaves with
five floats under CMD yarns 81 with a repeat of six CMD yarns 81. Thus, in fabric
80, the repeat of the upper MD yarns, which is three, is an equal multiple of the
repeat of lower MD yarns, which is six.
[0075] A variety of other weave patterns employing the paired stacked weave construction
of the instant invention may be constructed within the scope of the present invention.
For example, in some applications it may be desirable to have MD yarn surface floats
over six or more CMD yarns. Such fabrics are readily constructed in accordance with
the teachings of the present invention.
1. An industrial fabric comprising a system of CMD yarns and a system of flat monofilament
MD yarns interwoven with said CMD yarns in a selected repeat pattern characterized
in that:
said MD yarns having paired upper and lower yarns stacked in vertical alignment;
and
the actual warp fill of at least said upper MD yarns is in the range of 80% - 125%.
2. A fabric according to claim 1 wherein said fabric is a papermaker's fabric for use
in the manufacture of non-woven sheet material.
3. A fabric according to claim 1 wherein said upper MD yarns are interwoven with floats
over a selected number of said CMD yarns such that the upper surface of the fabric
is predominated by said upper MD yarn floats.
4. A fabric according to claim 3 wherein said MD yarns interweave with said CMD yarns
with hidden knuckles.
5. A fabric according to claim 3 wherein said lower MD yarns are interwoven with said
CMD yarns in an inverted image of the repeat of said upper MD yarns whereby the bottom
surface of the fabric is also predominated by floats of said MD yarns.
6. A fabric according to claim 1 wherein said upper MD yarns repeat with respect to X
of said CMD yarns with a float of Y, where Y is an integer greater than 1 and X is
an integer not greater than 2Y, and said lower MD yarns are woven in the inverse thereof.
7. A fabric according to claim 1 wherein said upper MD yarns repeat with respect to X
of said CMD yarns with a float of Y, where Y is an integer greater than 1 and X is
an integer not greater than 2Y, and said lower MD yarns repeat with respect to Z of
said CMD yarns, where Z is an integer which is an equal multiple of, or equally divisible
by, X.
8. A fabric according to claim 7 wherein said lower MD yarns repeat with respect to Z
of said CMD yarns with a float of W, where W is an integer greater than 1 and W is
not less than half of Z.
9. A fabric according to claim 1 wherein at least said upper MD yarns have an aspect
ratio of at least 3:1.
10. A fabric according to claim 1 wherein the actual warp fill of said lower MD yarns
is also in the range of 80% - 125%.
11. A fabric according to claim 1 wherein all of said MD yarns have an aspect ratio of
at least 3:1 and the total actual warp fill of all of said MD yarns is in the range
of 160% - 250%.
12. A fabric according to claim 1 wherein said fabric consists essentially of all monofilament
yarns.
13. A fabric according to claim 1 wherein said system of CMD yarns includes at least upper
and lower layers of CMD yarns.
14. A fabric according to claim 13 wherein said upper MD yarns are interwoven with floats
over a selected number of said upper layer CMD yarns such that the upper surface of
the fabric is predominated by said upper MD yarn floats.
15. A fabric according to claim 14 wherein said lower MD yarns are interwoven with said
CMD yarns in an inverted image of the repeat of the respective upper MD yarns of said
MD yarn pairs whereby the bottom surface of the fabric is also predominated by floats
of said MD yarns.
16. A fabric according to claim 15 wherein said CMD yarn system further includes a middle
layer of CMD yarns and wherein said MD yarns interweave with said middle layer CMD
yarns with hidden interior knuckles.
17. A fabric according to claim 13 wherein said CMD yarn system further includes a middle
layer of CMD yarns and wherein said MD yarns interweave with said middle layer CMD
yarns with hidden interior knuckles.
18. A fabric according to claim 17 wherein said upper MD yarns repeat with respect to
three of said upper layer CMD yarns with a float of two, and said lower MD yarns are
woven in the inverse thereof.
19. A fabric according to claim 17 wherein said upper MD yarns repeat with respect to
four of said upper layer CMD yarns with a float of two, and said lower MD yarns are
woven in the inverse thereof.
20. A fabric according to claim 17 wherein said upper MD yarns repeat with respect to
X of said upper layer CMD yarns with a float of Y, where Y is an integer greater than
1 and X is an integer not greater than 2Y, and said lower MD yarns are woven in the
inverse thereof.
21. A fabric according to claim 17 wherein said upper MD yarns repeat with respect to
X of said upper layer CMD yarns with a float of Y, where Y is an integer greater than
1 and X is an integer not greater than 2Y, and said lower MD yarns repeat with respect
to Z of said lower layer CMD yarns, where Z is an integer which is an equal multiple
of, or equally divisible by, X.
22. A fabric according to claim 21 wherein said lower MD yarns repeat with respect to
Z of said lower layer CMD yarns with a float of W, where W is an integer greater than
1 and W is not less than half of Z.
23. A papermakers fabric comprising a single layer system of CMD yarns and a system of
flat monofilament MD yarns interwoven with said CMD yarns in a selected repeat pattern
characterized in that:
said MD yarns have paired upper and lower yarns stacked in vertical alignment;
and
the actual warp fill of at least said upper MD yarns is in the range of 80% - 125%.
24. A papermakers fabric according to claim 23 wherein said upper MD yarns are interwoven
with floats over a selected number of said CMD yarns such that the upper surface of
the fabric is predominated by said upper MD yarn floats.
25. A papermakers fabric according to claim 24 wherein said MD yarns interweave with said
CMD yarns with hidden knuckles.
26. A papermakers fabric according to claim 24 wherein said lower MD yarns are interwoven
with said CMD yarns in an inverted image of the repeat of said upper MD yarns whereby
the bottom surface of the fabric is also predominated by floats of said MD yarns.
27. A papermakers fabric according to claim 24 wherein said upper MD yarns repeat with
respect to four of said upper layer CMD yarns with a float of three and said lower
MD yarns are woven in the inverse thereof.
28. A papermakers fabric according to claim 27 wherein said MD yarns are interwoven with
said CMD yarns in a balanced weave pattern such that said MD yarn system consists
of two types of MD yarn pairs which are offset by two of said CMD yarns such that
alternate CMD yarns are not woven in knuckles by said MD yarns and such that the CMD
yarns which are woven in knuckles by said MD yarns are crimped by the weaving of said
MD yarns.
29. A papermakers fabric according to claim 28 wherein said alternate CMD yarns which
are not woven in knuckles by said MD yarns are larger than the CMD yarns which are
woven in knuckles by said MD yarns.
30. A papermakers fabric according to claim 23 wherein said upper MD yarns repeat with
respect to X of said CMD yarns with a float of Y, where Y is an integer greater than
1 and X is an integer not greater than 2Y, and said lower MD yarns are woven in the
inverse thereof.
31. A papermakers fabric according to claim 23 wherein said upper MD yarns repeat with
respect to X of said CMD yarns with a float of Y, where Y is an integer greater than
1 and X is an integer not greater than 2Y, and said lower MD yarns repeat with respect
to Z of said CMD yarns, where Z is an integer which is an equal multiple of, or equally
divisible by, X.
32. A papermakers fabric according to claim 31 wherein said lower MD yarns repeat with
respect to Z of said CMD yarns with a float of W, where W is an integer greater than
1 and W is not less than half of Z.
33. A papermakers fabric according to claim 23 wherein at least said upper MD yarns have
an aspect ratio of at least 3:1.
34. A papermakers fabric according to claim 23 wherein the actual warp fill of said lower
MD yarns is also in the range of 80% - 125%.
35. A papermakers fabric according to claim 23 wherein all of said MD yarns have an aspect
ratio of at least 3:1 and the total actual warp fill of all said MD yarns is in the
range of 160% - 250%.
36. A papermakers fabric according to claim 23 wherein said fabric consists essentially
of all monofilament yarns.
37. A industrial fabric comprising a system of CMD yarns interwoven with a system of flat
monofilament MD yarns in a selected repeat pattern wherein said MD yarns comprise
pairs of upper and lower MD yarns stacked in vertical alignment, and wherein at least
said upper MD yarns have an aspect ratio greater than 3:1.
38. A papermakers fabric comprising a system of flat MD yarns having a thickness t interwoven
with a system of CMD yarns characterized in that:
said MD yarns are woven with selected CMD yarns having a diameter d in bracing
contact over a contact arc of ϑ degrees such that the contact bracing area CBA of
the MD yarn interweavings with said selected CMD yarns is related to the degree of
contact arc ϑ as follows:
39. A papermakers fabric according to claim 38 wherein ϑ is at least 60° and t is about
0.2mm.
40. A papermakers fabric according to claim 38 wherein said fabric consists essentially
of all monofilament yarns.
41. A papermakers fabric according to claim 38 wherein ϑ is about 101°.
42. A papermakers fabric according to claim 38 wherein the average permeability over the
fabric is 90 CFM.
43. A papermakers fabric according to claim 42 wherein the range of permeability is 87-93
CFM.
44. A papermakers fabric according to claim 38 wherein the CMD yarn system is a single
layer of CMD yarns.
45. A papermakers fabric according to claim 44 wherein said MD yarns interweave with knuckles
only with alternate CMD yarns of said single CMD yarn layer, said alternate CMD yarns
being said selected CMD yarns.
46. A papermakers fabric according to claim 45 wherein the diameter of the alternate non-selected
CMD yarns is about t + d.
47. A papermakers fabric according to claim 45 wherein t is about 0.2mm, d is about 0.6mm,
the diameter of the alternate non-selected CMD yarns is about 0.8mm and ϑ is about
101°.
48. A papermakers fabric according to claim 47 wherein the average permeability over the
fabric is 90 CFM.
49. A papermakers fabric according to claim 48 wherein the range of permeability is 87-93
CFM.
50. A papermakers fabric comprising a system of CMD yarns interwoven with a system of
flat monofilament MD yarns as structural weave components in a selected repeat pattern
characterized in that: said MD yarns consist essentially of yarns having an aspect
ratio greater than 3:1.
51. A papermakers fabric according to claim 50 wherein said MD yarns comprise pairs of
upper and lower MD yarns stacked in vertical alignment and the actual warp fill of
at least said upper MD yarns is in the range of 80% - 125%.
52. A papermakers fabric according to claim 50 wherein said CMD yarn system further includes
an upper, middle and lower layer of CMD yarns and wherein said MD yarns interweave
with said middle layer CMD yarns with hidden interior knuckles; said upper MD yarns
interweaving with said upper and middle layer CMD yarns, and said lower MD yarns interweaving
with said lower and middle layer CMD yarns.
53. A papermakers fabric according to claim 50 wherein said fabric consists essentially
of all monofilament yarns.
54. A papermakers fabric according to claim 50 wherein said CMD yarn system comprises
a single layer of CMD yarns and wherein said MD yarns interweave with said single
layer of CMD yarns with hidden interior knuckles.
55. A papermakers fabric comprising a system of MD yarns interwoven with a single layer
of system of CMD yarns characterized in that: said CMD yarns include yarns of at least
two different diameters and are interwoven in a selected repeat pattern such that
the CMD yarns having the relatively smaller diameter are crimped significantly more
than the CMD yarns having the relatively larger diameter.
56. A papermakers fabric according to claim 55 wherein said:
MD yarns are flat monofilament yarns having paired upper and lower yarns stacked
in vertical alignment; and
the actual warp fill of at least said upper MD yarns is in the range of 80% - 125%.
57. A papermakers fabric according to claim 55 wherein CMD yarns alternate between a first
relatively larger diameter and a second relatively smaller diameter in said single
CMD layer.
58. A papermakers fabric according to claim 57 wherein said MD yarns are flat monofilament
yarns having a thickness t and said first diameter is approximately equal to said
second diameter plus t.
59. A papermakers fabric according to claim 57 wherein said first diameter is about 0.8mm,
said second diameter is about 0.6mm, and said MD yarns are flat monofilament yarns
having a thickness of about 0.2mm.
60. A papermakers fabric comprising a single layer of CMD yarns interwoven with a system
of MD yarns characterized in that alternate CMD yarn are crimped to a significantly
greater degree than the respective adjacent CMD yarns in said single CMD layer.
61. A papermakers fabric according to claim 60 wherein said CMD yarns are flat monofilament
yarns having an aspect ratio greater than 3:1.
62. A papermakers fabric having opposing ends comprising a system of flat monofilament
MD yarns interwoven with a system of CMD yarns characterized in that:
a series of orthogonal end loops are formed on each end of said fabric from selected
MD yarns which are looped back and interwoven with said CMD yarns directly beneath
themselves.
63. A papermakers fabric according to claim 62 wherein:
said MD yarns comprise pairs of vertically aligned upper and lower MD yarns with
the orthogonal end loops formed from upper MD yarns and the respective lower MD yarns
are trimmed back a selected distance from the end of the fabric such that the looped
MD yarns are interwoven with said CMD yarns in the space vacated by the respective
trimmed lower MD yarn.
64. A papermakers fabric according to claim 63 wherein:
all orthogonal end loop forming upper MD yarns are interwoven with said CMD yarns
directly beneath themselves;
all lower MD yarns are trimmed back a selected distance from the end of the fabric;
and
the remaining upper MD yarns are interwoven with the CMD yarns directly beneath
themselves and retain the endmost CMD yarns in the fabric.
65. A papermakers fabric according to claim 64 wherein:
the orthogonal end loop forming upper MD yarns are all back woven substantially
the same distance into the end of the fabric which distance is greater than the back
weaving of the remaining upper MD yarns; and
the lower MD yarns which are paired with loop forming upper MD yarns are trimmed
back a greater distance from the end of the fabric than the remaining lower MD yarns.
66. A papermakers fabric according to claim 64 wherein the actual warp fill of at least
said upper MD yarns is in the range of 80% - 125%.
67. A papermakers fabric according to claim 64 wherein said lower MD yarns are interwoven
with said CMD yarns in an inverted image of the respective upper MD yarns of said
MD yarn pairs.
68. A papermakers fabric according to claim 64 wherein every second upper MD yarn on each
end of the fabric is an orthogonal loop forming yarn.
69. A papermakers fabric according to claim 64 wherein every third upper MD yarn on each
end of the fabric is an orthogonal loop forming yarn.
70. A papermakers fabric according to claim 64 wherein at least said upper MD yarns have
an aspect ratio of at least 3:1.
71. A papermakers fabric according to claim 64 wherein said CMD yarn system comprises
a single layer of CMD yarns.
72. A papermakers fabric comprised of a system of MD yarns interwoven with a single layer
of CMD yarns characterized in that: a series of orthogonal end loops are formed on
opposing ends of said fabric from selected MD yarns which loop back and interweave
with the CMD yarns directly beneath themselves.
73. A papermakers fabric according to claim 72 wherein:
said MD yarns comprise pairs of vertically aligned upper and lower MD yarns with
the orthogonal end loops formed from upper MD yarns and the respective lower MD yarns
are trimmed back a selected distance from the end of the fabric such that the looped
MD yarns are interwoven with said CMD yarns in the space vacated by the respective
trimmed lower MD yarn.
74. A papermakers fabric according to claim 73 wherein:
all orthogonal end loop forming upper MD yarns are interwoven with said CMD yarns
directly beneath themselves;
all lower MD yarns are trimmed back a selected distance from the end of the fabric;
and
the remaining upper MD yarns are interwoven with the CMD yarns directly beneath
themselves and retain the endmost CMD yarns in the fabric.
75. A papermakers fabric according to claim 74 wherein:
the orthogonal end loop forming upper MD yarns are all back woven substantially
the same distance into the end of the fabric which distance is greater than the back
weaving of the remaining upper MD yarns; and
the lower MD yarns which are paired with loop forming upper MD yarns are trimmed
back a greater distance from the end of the fabric than the remaining lower MD yarns.
76. A papermakers fabric according to claim 74 wherein the actual warp fill of at least
said upper MD yarns is in the range of 80% - 125%.
77. A papermakers fabric according to claim 74 wherein said lower MD yarns are interwoven
with said CMD yarns in an inverted image of the respective upper MD yarns of said
MD yarn pairs.
78. A papermakers fabric according to claim 74 wherein every second upper MD yarn on each
end of the fabric is an orthogonal loop forming yarn.
79. A papermakers fabric according to claim 74 wherein every third upper MD yarn on each
end of the fabric is an orthogonal loop forming yarn.
80. A papermakers fabric according to claim 74 wherein at least said upper MD yarns have
an aspect ratio of at least 3:1.
81. A papermakers fabric having at least one system of monofilament MD yarns interwoven
with a system of CMD yarns to define an open fabric with opposing ends characterized
in that:
each opposed end has a first set of said MD yarns looped back and interwoven with
said CMD yarns directly beneath themselves to define a series of orthogonal end loops;
and
each opposed end has a second set of said MD yarns, interspersed between the first
set, looped back and interwoven with said CMD yarns directly beneath themselves to
retain the endmost CMD yarns in the fabric.
82. A papermakers fabric according to claim 81 wherein:
said MD yarns comprise pairs of vertically aligned upper and lower MD yarns with
the orthogonal end loops formed from upper MD yarns and the respective lower MD yarns
trimmed back a selected distance from the end of the fabric such that the looped MD
yarns are interwoven with said CMD yarns in the space vacated by the respective trimmed
lower MD yarns.