Note: Descriptions are shown in the official language in which they were submitted.
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MULTI-LAYER FABRIC
Field of the Invention
The present invention relates generally to papermaking technology,
and more specifically, to fabrics for use with a papermaking machine.
D'escription'of the Prior Art
During the papermaking process, a cellulosic fibrous web is formed by
depositing a fibrous slurry, that is, an aqueous dispersion of cellulose
fibers,
onto a moving forming fabric in the forming section of a papermaking
machine. A large amount of water is drained from the slurry through the
forming fabric, leaving the cellulosic fibrous web on the surface of the
forming fabric.
The newly formed cellulosic fibrous web proceeds from the forming
section to a press section, which includes a series of press nips. The
cellulosic
fibrous web passes through the press nips supported by a press fabric, or, as
is
often the case, between two such press fabrics. In the press nips, the
cellulosic
fibrous web is subjected to compressive forces which squeeze water
therefrom, and which adhere the cellulosic fibers in the web to one another to
turn the cellulosic fibrous web into a paper sheet. The water is accepted by
the
press fabric or fabrics and, ideally, does not return to the paper sheet.
The paper sheet finally proceeds to a dryer section, which includes at
least one series of rotatable dryer drums or cylinders, which are internally
heated by steam. The newly formed paper sheet is directed in a serpentine path
sequentially around each in the series of drums by a dryer fabric, which holds
the paper sheet closely against the surfaces of the drums. The heated drums
reduce the water content of the paper sheet to a desirable level through
evaporation.
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The forming, press and dryer fabrics all take the form of endless loops
on the paper machine and function in the manner of conveyors. It should
further be appreciated that paper manufacture is a continuous process which
proceeds at considerable speeds. That is to say, the pulp is continuously
deposited onto the forming fabric in the forming section, while a newly
manufactured paper sheet is continuously wound onto rolls after it exits from
the dryer section.
Woven fabrics take many different forms. For example, they may be
woven endless, or flat woven and subsequently rendered into endless form
with a seam.
Forming fabrics play a critical role during the paper manufacturing
process. One of its functions, as implied above, is to form and convey the
paper product being manufactured to the press section. The forming fabric
design, however, needs to address water removal and sheet formation
constraints. That is, forming fabrics are designed to allow water to pass
through (i.e. control the rate of drainage) while at the same time prevent
fiber
and other solids from passing through with the water. If drainage occurs too
rapidly or too slowly, the sheet quality and machine efficiency suffers. To
control drainage, the space within the forming fabric for the water to drain,
commonly referred to as void volume, must be properly designed.
Contemporary forming fabrics are produced in a wide variety of styles
designed to meet the requirements of the paper machines on which they are
installed for the paper grades being manufactured. Generally, they comprise a
base fabric woven from monofilament, and may be single-layered or multi-
layered. The yams are typically extruded from any one of several synthetic
polymeric resins, such as polyamide and polyester resins, used for this
purpose
by those of ordinary skill in the paper machine clothing arts.
The design of forming fabrics additionally involves a compromise
between the desired fiber support and fabric stability. A fine mesh fabric may
provide the desired paper surface and fiber support properties, but such
design
may lack the desired stability resulting in a short fabric life. By contrast,
coarse mesh fabrics provide stability and long life at the expense of fiber
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support and the potential for marking. To minimize the design tradeoff and
optimize both support and stability, multi-layer fabrics have been developed.
For example, in double and triple layer fabrics, the forming side is designed
for sheet and fiber support while the wear side is designed for stability,
void
volume, and wear resistance.
Those skilled in the art will appreciate that fabrics are created by
weaving, such that the resulting fabric has a weave pattern which repeats in
both the warp or machine direction (MD) and the weft or cross-machine
direction (CD).
Multi-layer fabrics, such as triple layer fabrics, may loosen during use
and cause unacceptable levels of abrasion within the structure. The present
invention provides a fabric which alleviates or overcomes such disadvantages.
SUMMARY OF THE INVENTION
In accordance with an illustrative embodiment of the present invention,
there is provided a fabric useful for fabricating paper, the fabric including
first
and second layers, each having machine direction (MD) yarns and cross-
direction (CD) yarns interwoven therewith. A plurality of binder pairs bind
the
first and second layers together. The binder pairs are interwoven so as to be
an
integral part of the first layer and contribute to a structure thereof. The
binder
pairs are a non-integral part of the second layer and do not contribute to a
structure thereof. During a repeat pattern , at least one of the two binder
yarns
of a binder pair is integrally woven with the yarns of the first layer and
passes
over outer surfaces of two non-consecutive yarns in the second layer. As a
result, a "double knuckle" binding structure may be formed which improves
integrity of the resulting composite fabric by reducing the length of the
binder
yarn path through the fabric.
The above and other features and advantages of the present invention
will become more apparent from the following detailed description of
preferred embodiments thereof.
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BRIEF DESCRIPTION OF THE DRAWINGS
The following detailed description, given by way of example and not
intended to limit the present invention solely thereto, will best be
appreciated
in conjunction with the accompanying drawings, in which like reference
numerals denote like elements and parts, wherein:
FIG. 1 is a cross-sectional view in the MD direction, of a portion of a
first fabric depicting a binder pair in accordance with the present invention;
FIG. 2 is a cross-sectional view in the MD direction, of a different
portion of the first fabric depicting cross-machine-direction (CD) yarns;
FIG. 3 is a wear-side photograph of the first fabric;
FIG. 4 is a photograph of a cross-section of the first fabric in the MID
direction;
FIG. 5 is a cross-sectional view in the CD direction of a portion of the
first fabric depicting a lower layer;
FIG. 6 is a cross-sectional view of a CD yarn arrangement of a second
fabric in accordance with the present invention;
FIG 7 depicts cross-sectional diagrams showing an illustrative CD
yam weave pattern of the first fabric;
FIG 8 shows cross-sectional diagrams depicting an illustrative CD yarn
weave pattern of the second fabric;
FIG. 9 is a photograph of a paper side view of the second fabric;
FIG. 10 is a photograph of a wear-side view of the second fabric;
FIGS. 11A, 11B, and 11C are diagrams of cross-sectional views of a
fabric according to another embodiment of the present invention;
FIGS. 11D and 11E are respective paper side and machine side views
of a fabric woven in accordance with the present invention;
FIGS. 12A and 12B are diagrams of cross-sectional views of a fabric
according to a further embodiment of the present invention;
FIGS. 12C and 12D are paper side and machine side views of a fabric
woven in accordance with the present invention;
FIGS. 13A and 13B are diagrams of cross-sectional views of a fabric
according to yet another embodiment of the present invention;
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FIGS. 13C and 13D are paper side and machine side views,
respectively, of a fabric woven in accordance with the present invention;
FIGS. 14A and 14B are diagrams of cross-sectional views of a fabric
according to an additional embodiment of the present invention;
FIGS. 14C and 14D are paper side and machine side views,
respectively, of a fabric woven in accordance with the present invention;
FIG. 15 is a diagram of cross-sectional view of a fabric according to
another embodiment of the present invention;
FIG. 16 is a view of a fabric pattern according to an embodiment of the
present invention;
FIG. 17A illustrates a further binder pair embodiment of the present
invention;
FIG. 17B illustrates a binder pair that may be used in a fabric with the
binder pair of FIG. 17A;
FIGS. 18A and 18B depict binder pairs that may be used in a fabric
according to the present invention; and
FIG. 19 illustrates a further binder pair embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, there is shown a cross-sectional illustration of
a binder yarn pair that forms a part of a composite fabric 100 in accordance
with an embodiment of the present invention. Fabric 100, which is
advantageously employed in a paper-making process, is composed of an array
of machine-direction (MD) yams (warp yams) and cross-machine direction
(CD) yams (weft yarns). MD yarns such as 1-20 are arranged in two layers,
with yams 1-10 arrayed in a bottom layer (or machine-side or "wear-side"
layer) and yams 11-20 arranged correspondingly in a top layer (or paper or
forming side layer).
CD yarns PA and PB together constitute a pair of binder yams, which
are depicted in a binder pair segment pattern 30 according to one embodiment
of the invention. Binder yarns PA, PB function to bind upper layer (LI) warp
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yarns to lower layer (L2) warp yarns to form the composite weave fabric 100.
Binding is accomplished in this embodiment by means of binder yarn PA
running in a cross-machine direction path that interweaves a number of warp
yarns in the top layer Ll, then crosses to lower layer L2 and interweaves a
number of lower layer warp yarns, and subsequently crossing back to the
upper layer to repeat the same or similar pattern. Likewise, binder yarn PB,
which may run parallel and adjacent to binder yarn PA, or intertwined with
yarn PA, binds upper and lower layer warp yarns in a similar fashion, and is
preferably complementary to yarn PA. That is, by suitably arranging the
crossing points of binder yarns PA,and PB, a substantially uniform top side
layer surface can be achieved, which is preferable for use as a paper side
layer.
As a result, the binder yarn pair 30 makes up a part of the structure of the
top
layer Ll, whereby the binder pair can be considered an "intrinsic" type of
binder pair which is an integral part of the top layer so as to contribute to
a
structure of the top layer. The binder pair, however, can be considered a non-
integral part of the bottom layer so as not to contribute to a structure of
the
bottom layer. (It is noted here that in other embodiments of the invention,
binder yarn pairs such as PA, PB can run in the MD direction to accomplish
binding, instead of the CD direction.)
In the fabric portion illustrated in FIG. 1, two "repeat patterns" are
shown, where the first comprises the portion of yarns PA and PB that bind the
20 warp yarns 1-20. The second repeat pattern binds MD yarns 1' to 20'.
Each repeat pattern may be considered as encompassing ten "columns" of
warps, with two layers per column, and two CD binder yarns PA, PB, together
constituting at least a portion of a "row" of wefts in both layers. Further,
binder yarns PA and PB may run in the CD direction closely to one another
such that, when viewed from the top of fabric 100, the binder yarns PA and
PB substantially overlay one another, i.e., they are nearly vertically
aligned.
Note that the use of the terms "columns" and "rows" herein is used for
convenience of explanation , and is not intended to limit the invention to MD
yarns and CD yarns that are necessarily orthogonal; for example, it is
possible
for the MD yarns to be skewed relative to one another. The warp yarns may
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be substantially uniform in cross section and spacing in the upper and lower
layers, such as the illustrated yarns 1-20, although it is quite possible to
employ warp yams of differing cross section and shapes (e.g., cylindrical,
elliptical, non-round or rectangular cross section) in the upper and lower
layers. In the CD direction, the weft yarns may be arranged with differing
patterns in successive rows, and the differing patterns may be designed to
repeat every N rows, as will be discussed later. The CD yarns may have. the
same or different shapes and diameters as the warp yams, and may be
composed of the same or different material.
'10 A characteristic feature of the binder yarn pair 30 is the formation of
"double knuckle" structures such as DK1 or DK2. That is, a double knuckle
DK2 is formed as yarn PA forms loops (knuckles) around outer surfaces of
two non-consecutive warp yarns, 7 and 9, while crossing to above yam 15 on
one side and above yarn 11' on the other side. The double knuckle DK1 is
likewise formed between yarns 2 to 4. Note that the illustrative double
knuckles DK1 and DK2 are formed such that the two non-consecutive yarns
that they loop around (e.g., yarns 7 and 9) have only one yarn (e.g., yarn 8)
in
the machine layer between them having an outer (bottom) surface of which the
binder yarn does not pass over. It is contemplated, however, that in other
binder embodiments of the present invention, more than one machine layer
yam can exist in between the "knuckles" of the double knuckle structure.
In any event, the double knuckle structure improves integrity of the
resulting composite fabric by reducing the length of the binder yarn path
through the fabric. That is, the structure results in short "internal floats"
for the
binder yarns. Better contact between the layers is achieved as compared to
conventional designs, causing less contact yam to yarn, and consequently less
internal wear. Another effect is that the binder becomes more symmetric and
therefore counteracts curling that can otherwise be a problem. The double
knuckle is also locked into place in the second layer due to increased contact
with multiple MD yams. This differs from a conventional binder yam which
has some freedom to slide along a single MD yarn. Moreover, the double
knuckle improves fabric seam strength.
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The binder material is often a medium to high shrinkage material,
while the backside shutes (e.g., weft W1 in layer L2 to be described below)
are low shrinkage as standard. In the prior art, that combination results in
significant curling. To balance the materials a more shrinkable bottom
material can be used in embodiments of the present invention. In this case,
the
external wear resistance on the backside is, however, influenced negatively
(less plain difference warp/shute). To compensate for the loss an alternative
backside pattern with longer (e.g., 10-shed) floats can be used.
The binders used in the present invention can have "internal floats"
that have a short or minimal length. The term internal float as used herein
refers to the distance that a yarn travels in between upper and lower warp
yarns of a composite fabric such as when crossing between the upper and
lower layers of the composite fabric. By utilizing a short internal float for
each binder, the reliability of the resulting composite fabric may be
improved.
In the embodiment of FIG. 1, for example, binder yarn PA interweaves warp
yarns 11 through 15 by passing over yarn 11, under yarn 12, over 13, under 14
and over 15. Yarn PA then crosses from top layer L1 to bottom layer L2 by
traveling between the two layers a distance (in the cross-machine direction)
corresponding to one warp yarn plus a short distance on either side. Thus, an
internal float Fl of binder yam PA can be considered the distance the yam
travels between only one top and bottom NM yarn (which are in the same
column in this embodiment), such as between yams 6 and 16, plus a short
inter-yarn distance on either side of these warp yams.
Binder yam PB, in the embodiment of FIG. 1, has a longer internal
:25 float, i.e., float F2, than the internal float F1 of yam PA. That is,
binder yarn
PB interweaves warp yams 1-4, then crosses from bottom layer L2 to top layer
L1 by traveling from beneath yarn 4 to the internal region between yarns 5, 15
and then between yams 6, 16, before arriving above yarn 17. Yarn PB then
interweaves yarns 17 through 20. Hence the internal float F2 of yarn PB is the
CD distance in the internal region traversed between yams 5 and 15 as well as
between yams 6 and 16, plus the short inter-yam distances on either side.
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Thus, internal float F2 has a length corresponding to two warp yarns (plus a
short inter-yarn distance on both sides).
The binder yarn pair pattern 30 with the above-described internal float
design, lends uniformity to the top surface of layer L1 (typically the paper
side
surface). That is, yarn PA interweaves top layer warp yarns 11-15 such that
alternating yarns 11, 13 and 15 are beneath the binding yarn PA, and then yarn
PB interweaves top layer yarns 17-20 such that alternating yarns 17 and 19 are
beneath yarn PB. As a result, alternating yarns 11, 13, 15, 17 and 19 are
beneath the binding pair yarns, whereby a substantially continuous plain-
weave type stitching pattern on the top surface is obtained. The binder yarn
pair 30 can be considered as an integral part of the top layer LI surface so
as
to contribute to the structure thereof. However, binder yarn pair 30 is not
considered an integral part of the bottom layer L2 surface, so as not to
contribute to the structure thereof, as will become apparent below.
FIG. 2 illustrates a cross-sectional view showing weft (CD) yarns W1
and W2 of fabric 100. These yarns together run in a repetitive weave pattern
50 interweaving warp yarns 1-20. Weft yarn W2 interweaves only the top
yarns 11-20 whereas weft yarn W 1 interweaves only the bottom yarns 1-10.
As seen in the photograph of FIG. 3, showing an illustrative wear-side
(bottom) view of fabric 100, weft yarns WI and W2 can run interspersed with
binder yarn pairs 30. In the shown embodiment, lower layer weft yarns W1 are
thicker than top layer weft yarns W2. (Only the wear side yarns W1 are clearly
visible in FIG. 3).
With segment pattern 50 of FIG. 2, yarn W1 travels in a path that runs
over MD yarn 1, beneath MD yarns 2-5, over MD yarn 6 and beneath MD
yarns 7-10. Thus, the pattern of yarn W1 passes over (or "contours around")
single warp yarns, such as yarns 1 and 6, every five yarns. The pattern can be
varied such that yarn W1 passes over every Nth warp yarn, where N is more or
fewer than five. Also, yarn W1 may pass over plural consecutive warp yarns
rather than a single warp yarn as shown. It is noted that the cross-sectional
area, shape (e.g., circular, elliptical, non-round, rectangular) and material
used
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for yarn W1 may be the same as, or different than, that used for the CD binder
yarns described earlier.
The yams of FIGS. 1 and 2 are combinable into a composite fabric that
has a 2:1 shute ratio. An exemplary total fabric containing these yarn
patterns
is discussed below in reference to FIG. 7.
FIG. 4 is a photograph of a cross section of illustrative fabric 100,
depicting a typical relationship between weft yarns W1, W2, binder yarns PA,
PB and warp yarns 1-20. Weft yarn W1 is significantly larger than the other
weft yarns in this embodiment. As a.result, the thickness of bottom layer L2
is
greater than that of top layer L1, whereby the bottom layer L2 is durable for
the machine side of the paper making process. It is further apparent that due
to
the interweaving of yarn W1 and the binder yarns PA, PB, the bottom layer
warp yarns 1-10 are no longer horizontally, aligned as previously depicted in
FIG. 1. On the other hand, the top layer Ll warp yarns 11-20 remain neatly
aligned, whereby a substantially uniform top layer surface is attained.
FIG. 5 is a cross-sectional view in the CD direction of a portion of
fabric 100 depicting the lower layer L2. As seen in the figure, the MD yarns
of fabric 100 such as yarn 1 do not run continuously in a horizontal plane.
Rather, they dip down periodically as at points A and B due to the
interweaving of the bottom layer weft yams W1. In the NM direction, it is
seen that binder yams as PA can be alternatingly interspersed with weft yarns
W1.
Referring now to FIG. 6, an alternative weft yarn arrangement/pattern
60 is shown which can be used in place of weft yarn arrangement 50 of FIG. 2
described above. That is, the yams of FIGS. 1 and 6 may be combined to form
an alternative embodiment of a composite fabric. (An exemplary full fabric
containing these yams is illustrated in FIG. 8 which is discussed below.) Weft
yarn arrangement 60 differs by the addition of a third weft yam, W3, that runs
adjacent to yarn W2 and interweaves the top layer warp yams 11-20. Weft
yarn W3 runs in a complementary fashion to yam W2 around warp yams 11-
20. For example, yam W2 runs under yarn 12, over yam 13, etc., while yarn
W3 runs over yam 12, under yam 13, and so on. Although weft yarn W3 is
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illustrated with dashed lines for clarity, it is understood that this yarn can
be
similar or identical in composition and dimensions to weft yarn W2. In the
cross section of FIG. 6, binder yarn pairs 30 are not shown for clarity;
however, in a typical arrangement, one weft yarn arrangement 60 is employed
in conjunction with one binder pair 30 to realize a 3:1 shute ratio. That is,
three yarn patterns in the top layer are employed for every weft yarn W1 in
the
bottom layer, with the three top layer yarn patterns comprising yarn W2, yarn
W3 and the yarns PA, PB of binder pair 30. This 3:1 shute arrangement will
be described further below in connection with FIGS. 8-10.
Referring now to FIG. 7, there is shown an illustrative embodiment of
a larger section of composite fabric 100. These figures illustrate an example
of
a row byrow weft pattern layout illustrated in cross-sectional views in FIG.
7,
and in a bottom view in FIG. 3. In FIG. 3, weft patterns in six rows R1 to R5
are depicted; and these are seen in the cross sectional diagrams of FIG. 7 for
rows R1 to R5 (where the warp yarn cross-sections are replaced with their
actual designating'numbers 11, 12, etc., for clarity of illustration).
In the exemplary weft yarn sequence of FIG. 7, each row such as Rl is
considered to contain four CD yarns, i.e., W1, W2, PA and PB. Row R1
contains yarns W1 and W2 designated in pattern 501 as well as binder yarns
PA, PB designated with pattern 301; and so forth. Each of the 40 yarns in the
sequence of FIG. 7 is also designated by a yarn number Y1-Y40. In this
example, the 40 yarns Y1-Y40 can make up a repeat pattern in the MD
direction. Thus, rows R1 to R10 are sequentially deployed in the MD
direction, and can be followed by another set of the same rows R1 to RIO, and
so forth. Typically, the wear-side layer weft yarn W1 is thicker than the
paper
side layer weft yarns W2 and the binder yarns PA, PB, such that two paper
side weave patterns, i.e., the weave pattern of yarn W2 and that of binder
pair
30, are employed for every wear-side yarn W1.
In the successive rows R1, R2, etc., the patterns of the wear side yarns
W1 are displaced in the CD direction. Thus, for example, in pattern 501 of row
Rl, yarn W1 loops over warp yarns 1 and 6; but in pattern 502 of row R2, yarn
WI loops over warp yarns 3 and 8; and so forth. In this manner, all of the
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bottom layer yams are interwoven. Similarly, the binder yarn patterns are
displaced from row to row: each repeat pattern 301 to 301o can each be thought
of as a different portion of the two combined repeat patterns 30 of FIG. 1.
For
instance, repeat pattern 301 is the same as the pattern 30 between sheds 1-20
of
FIG. 1; whereas repeat pattern 302 is the same as the pattern 30 between sheds
9, 19 and 9', 19' of FIG. 1. Thus, as the binding yarn patterns are displaced
from row to row, a complete binding of the upper and lower layers is
achieved.
With reference now to RG. 8, an alternative weft yarn sequence is
illustrated. This sequence differs from that of FIG. 7 in that the weft yarn
arrangement 50 is replaced with the arrangement 60 shown in FIG. 6, resulting
in the above-mentioned 3:1 shute ratio. In particular, three top (paper) layer
weft patterns are deployed - i.e., the patterns of wefts W2, W3 and that of
the
paired binder 30 - for every lower layer (wear-side layer) weft yarn W l.
Thus,
each of rows R 1 to R 10 is considered to contain five yarns, whereby a total
of
50 yarns Y1 to Y50 are contained in each repeat pattern in the MD direction.
FIGS. 9 and 10 are paper side and wear side photographs, respectively,
of an actual fabric, designated as I00a, that contains the weave pattern
sequence of FIG. 8. It is seen from the top view that each row such as RI
contains three adjacent top layer weave patterns formed from yarns W2, W3
and the binders PA, PB of pattern 301. From the wear side view it is seen that
each row as R1 contains one bottom layer weft yarn W1. Thus, each row Ri
contains one weave arrangement 60i and one paired binder 30i.
In yet another variation of the present invention, double cross parallel
(DCP) type binder pairs may be employed in rows or locations interspersed
with any of the binder patterns and weft patterns discussed above. Such DCP
type binder pairs are disclosed in U.S. Patent application S/N 10/334,166
entitled DOUBLE CROSS PARALLEL BINDER FABRIC. In a DCP binder pair, the
two binders pass over at least one common (same) yarn on an outer surface of a
layer such as the paper side layer within a repeating pattern.
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Embodiments of the invention to be described below include DCP
binder pairs. In particular, the below embodiments pertain to a fabric such as
a
triple layer fabric which may be utilized in a papermaking process. Such
triple
Iayer fabric may include a first (upper) layer and a second (lower) layer in
which each of the first and second layers has a system of machine-direction
(MD) yarns and cross-machine direction (CD) yarns interwoven therewith.
The first layer may be a paper side or faceside layer upon which the
cellulosic
paper/fiber slurry is deposited during the papermaking process and the second
layer may be a machine side or backside layer. The first and second layers
may be held together by use of a number of stitching or binding yams. Such
stitching yarns may be a number of CD and/or MD yarns. For example, a
number of pairs of CD yarns may be used wherein the two yarns of each pair
are located adjacent to each other and work in parallel. A pair of such CD
yams may be an integral or non-integral part of the weave pattern of either or
both of the first and second layers and may also bind the two layers together.
FIG. 11A illustrates a portion or a repeating pattern of a binding pair
88. More specifically, FIG. 11A is a cross-sectional view of a part of a
fabric
100' which includes a first (paper side) layer L14 and a second (machine side)
layer L16 having a plurality of MD yams 21-38 in the paper side layer L14, a
plurality of MD yams 41-58 in the machine side layer L16, and a number of
binding pairs 88 each having CD yarns 90 and 92 interwoven with the MD
yams. As shown therein, CD yarn 90 passes over MD yams 21, 24, 28, and
32 and passes under MD yarns 22, 26, 31, 34 and 38 of the paper side layer
L14, and passes under MD yam 56 of the machine side layer L16. CD yarn 92
passes over MD yarns 21, 32, and 36 and passes under MD yams 22, 24, 28,
31, 34, and 38 of the paper side layer L14, passes over MD yams 42, 44, 48,
and 51 and passes under MD yarn 46 of the machine layer L16.
A plurality of binding pairs 88 may be interwoven into fabric 100' as
shown in FIG. 11D (which is a paper side view of the fabric) and FIG. 11E
(which is a machine side view of the fabric). Additionally, a number of CD
pairs 66 may also be interwoven into the fabric 100' and arranged therein
between adjacent ones of the binding pairs 88. Each of the CD pairs may have
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CD yams 62 and 64 which may be interwoven with the MD yarns of the paper
side layer L14 and the machine side layer L16 as shown in FIG. 11C. Further,
a number of pairs 70 each including CD yarns 72 and 74 may also be
interwoven with the MD yarns of the paper side layer L14 and machine side
layer L16 of the fabric 100' as, for example, shown in FIG. 11B.
Therefore, in the fabric 100', each of the yarns 90 and 92 of the
binding pair 88 passes over MD yarns 21 and 32 on an outer surface of the
paper side layer L14. Such type of binding pair is hereinafter referred to as
a
double cross parallel (DCP) type binder pair. Accordingly, the fabric 100' has
two interwoven layers of CD and MD yarns which are held together by a
plurality of DCP type binder pairs wherein the two yarns of each such binder
pair pass over two MD yarns on an outer surface of the paper side L14 within
a repeat pattern.
Another fabric will now be described with reference to FIGS. 12A-D.
FIG. 12A illustrates a portion or a repeating pattern of a binding pair
108 of a fabric. 200 having a first (paper side) layer 114 and a second
(machine
side) layer 116. More specifically, FIG. 12A is a cross-sectional view
illustrating a plurality of MD yarns 120-138 in the paper side layer 114, a
plurality of MD yarns 140-158 in the machine side layer 116, and binding pair
108 having CD yarns 110 and 112 interwoven with the MD yarns. As shown
in FIG. 12A, in binder pair 108, CD yarn 110 passes over MD yarns 120, 128,
132, and 136 and passes under MD yarns 122, 126, 130, 134 and 138 of the
paper side layer 114, and passes under MD yarn 144 of the machine side layer
116. CD.yarn 112 passes over MD yarns 120, 124, and 128 and passes under
MD yarns 122, 126, 130, 132, 136 and 138 of the paper side layer 114, and
passes over MD yarns 152, 156, and 158 and passes under MD yarn 154 of the
machine layer 116. A number of binding pairs 108 may be interwoven into
fabric 200 as shown in FIG. 12C (which is a paper side view of the fabric) and
FIG. 12D (which is a machine side view of the fabric).
Additionally, a number of binder pairs 106 each having CD yarns 160
and 162 may also be interwoven with the MD yarns of the fabric 200 and
arranged therein in an alternating manner with the binding pairs 108. Each of
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the binder pairs 106 (which may be referred to as a support shute binder
(SSB) type) may have CD yarns 160 and 162 which may be interwoven with
the MD yarns of the paper side layer 114 and the machine side layer 116 as
shown in FIG. 12B. As illustrated in FIG. 12B, CD yarns 160 and 162 do not
pass over one or more same MD yarns on an outer surface of the paper side
layer 114. Further, a number of CD yarns 170 may also be interwoven into
the fabric 200 and arranged such that respective ones of CD yarns 170 are
located on either side of binding pairs 106 and 108 as, for example, shown in
FIG. 12C. CD yarns 170 may be similar to CD yarns 62 and 64 shown in FIG.
11C.
Therefore, in the fabric 200, each of the yarns 110 and 112 of the
binding pair 108 passes over MD yarns 120 and 128 on an outer surface of the
paper side layer 114. Thus, binding pair 108 is a DCP type binder pair.
Accordingly, the fabric 200 has two interwoven layers of CD and MD yarns
which are held together by a plurality of DCP type binder pairs wherein the
two yarns of each such binder pair pass over two MD yarns on an outer
surface of the paper side 114 within a repeat pattern. Further, the
arrangement
of binders in the fabric 200 enables relatively high permeability.
Another fabric will now be described with reference to FIGS. 13A-D.
FIG. 13A illustrates a portion or a repeating pattern of a binding pair
.208 having a first (paper side) layer 214 and a second (machine side) layer
216. More specifically, FIG. 13A is a cross-sectional view of a part of a
fabric 300 illustrating a plurality of MD yarns 220-238 in the paper side
layer
214, a plurality of MD yarns 240-258 in the machine side layer 216, and
binding pair 208 having CD yarns 210 and 212 interwoven with the MD yarns.
As shown therein, CD yarn 212 passes over MD yarns 220, 224, 228, 232, and
236 and passes under MD yarns 222, 226, 234 and 238 of the paper side layer
214, and passes under MD yarn 250 of the machine side layer 116. CD yarn
210 passes over MD yarns 228 and 232 and passes under MD yarns 230 and
234 of the paper side layer 214, and passes over MD yams 240, 244, 246, 256,
and 258 and passes under MD yarn 240 of the machine layer 216. A number
of binding pairs 208 may be interwoven into fabric 300 as shown in FIG. 13C
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(which is a paper side view of the fabric) and FIG. 13D (which is a machine
side view of the fabric).
Additionally, a number of binding pairs 206 may be interwoven in the
fabric 300 and arranged therein in an alternating manner with the binding
pairs
208. Each of the pairs 206 (which may be SSB type binders) may have CD
yarns 260 and 262 which may be interwoven with the MD yarns of the paper
side layer 214 and the machine side layer 216 as shown in FIG. 13B. As
illustrated in FIG. 13B, CD yarns 260 and 262 do not pass over one or more
same MD yarns on an outer surface of the paper side layer 214.
Further, a number of CD yarns 270 may also be interwoven into the
fabric 300 and arranged such that respective ones of CD yarns 270 are located
on either side of binding pairs 208 and CD pairs 206 as, for example, shown in
FIG. 13C. CD yarns 270 may be similar to CD yarns 62 and 64 shown in FIG.
11C.
Therefore, in the fabric 300, each of the yarns 210 and 212 of the
binding pair 208 passes over MD yarns 228 and 232 on an outer surface of the
paper side layer 214. Thus, binding pair 208 is a DCP type binder pair.
Accordingly, the fabric 300 has two interwoven layers of CD and MD yarns
which are held together by a plurality of DCP type binder pairs and SSB type
binder pairs wherein the two yarns of each DCP binder pair pass over two MD
yarns on an outer surface of the paper side 14 within a repeat pattern.
Further,
the arrangement of binders in the fabric 300 may provide a direct pass from
the top to the bottom and, as such, may improve the internal wear resistance
of
the fabric as compared to fabrics having other arrangements.
Yet another fabric will now be described with reference to FIGS. 14A-
D. -
FIG. 14A illustrates a portion or a repeating pattern of a binding pair
308 of a fabric 400 having a first (paper side) layer 314 and a second
(machine
side) layer 316. More specifically, FIG. 14A is a cross-sectional view
illustrating a plurality of MD yarns 320-338 in the paper side layer 314, a
plurality of MD yarns 340-358 in the machine side layer 316, and binding pair
308 having CD yarns 310 and 312 interwoven with the MD yarns. As shown,
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CD yarn 312 passes over MD yarns 320, 324, and 328 and passes under NM
yarns 322, 326, and 330 of the paper side layer 314, and passes under MD
yarn 354 of the machine side layer 316. CD yarn 310 passes over MD yarn
328 and passes under MD yarn 330 of the paper side layer 314, and passes
over MD yarns 342, 344, and 346 and passes under MD yarn 340 of the
machine layer 316. A number of binding pairs 308 may be interwoven into
fabric 400 as shown in FIG. 14C (which is a paper side view of the fabric) and
FIG. 14D (which is a machine side view of the fabric).
Additionally, a number of binder pairs 306 may also be interwoven
into the fabric 400 and arranged therein in an alternating manner with the
binding pairs 308.. Each of the binder pairs 306 (which may be SSB type
binders) may have CD yarns 360 and 362 which may be interwoven with the
MD yarns of the paper side layer 314 and the machine side layer 316 as shown
in FIG. 14B. As illustrated in FIG. 14B, CD yarns 260 and 262 do not pass
over one or more same MD yarns on an outer surface of the paper side layer
314.
Further, a number of CD yarns 370 may also be interwoven into the
fabric 400 and arranged such that respective ones of CD yarns 370 are located
on either side of binding pairs 306 and 308 as, for example, shown in FIG.
14C. CD yams 370 may be similar to CD yarns 62 and 64 shown in FIG. I1C.
Therefore, each of the yarns 310 and 312 of the binding pair 308
passes over MD yarn 328 on an outer surface of the paper side layer 314.
Thus, binding pair 308 is a DCP type binder pair.
Accordingly, the fabric 400 has two interwoven layers of CD and NM
yams whici are held together by a plurality of DCP type binder pairs and SSB
type binder pairs wherein the two yarns of each DCP binder pair pass over
only one MD yarn on an outer surface of the paper side 314 within a repeat
pattern. As a result, the MD or warps yams may be offstacked and a
symmetric binder contour may be obtained. Further, such arrangement may
minimize the number of crossings, decrease the level of marking, decrease the
caliper, and improve the seamability as compared to fabrics having other
arrangements.
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In the above-described fabrics, the CD yarns of the DCP type binder
pairs do not cross each other as they pass below a transitional top NID yarn.
Instead, such yams are adjacent to each other as they pass over one or more
same MD yarns.
Although specific patterns have been described above, the present
invention is not so limited. For example, other patterns for the binder pairs
such as that shown in FIG. 15 which includes a combination of DCP type
binder pair and SSB binder pair within a repeat pattern. More specifically,
FIG. 15 is a cross-sectional view of a part of a fabric 500 which includes a
first (paper side) layer 514 and a second (machine side) layer 516 having a
plurality of MD yams therein and a number of binder pairs each having CD
yarns 510 and 520. As shown in FIG. 15, CD yarns 510 and 520 each pass
over MD yarns 530 and 532. The binder pair of FIG. 15 includes a number of
DCP portions 550 and SSB portions 540. FIG. 16 illustrates a weaving pattern
for a fabric which may use binder pairs. Additionally, the weave patterns for
the upper (paper side) layer may be plain weave pattern or other patterns.
Similarly, the lower (machine side) may be woven on 4, 5, or 6 sheds, or other
arrangements may be used.
FIG. 17A illustrates in cross section yet another binder pair, 630, in
accordance with the invention, which forms a part of a composite fabric 600.
Binder yarns 610 and 620 together comprise binder pair 630, which binds
together the yarns of paper side layer L1 and wear (machine) side layer L2.
Binder pair 630 can be considered to provide a combination of the double
-knuckle structure of the binder 30 described above and the DCP binders also
described above. The shown pattern of binder pair 630 can be a repeat pattern
which repeats in the CD direction. Yarn 610 forms a double knuckle DK
around yarns 2 to 4, and this double knuckle affords the advantages mentioned
earlier, e.g., improving integrity of the resulting composite fabric by
reducing
the length of the binder yam path through the fabric, improving fabric seam
strength, etc. In addition, the co-location of binder yarns 610 and 620 at
locations above warp yarns 11 and 17, for example, renders the binder pair a
DCP-type binder with the attendant advantages.
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Binder pair 630 can be implemented in a composite fabric interspersed
with other binders, such as with binder pair 30 shown in FIG. 17B (which is
the same as the binder pair shown in FIG. 1). For instance, considering the
wear side view of FIG. 3, binder pair 630 can be interspersed such that the
shown pattern from top to bottom changes from 50, 30, 50, 30, 50, 30, 50, 30,
... to 50, 30, 50, 630, 50, 30, 50, 630, .... Alternatively, binder pair 630
can
be used as the sole binder type of a fabric.
FIGS. 18A and 18B illustrate binder pairs, 108 and 670, respectively,
that can be employed in another fabric 680 in accordance with the invention.
Thus, binders 108 and 670 may be utilized interspersed with one another
within fabric 680, e.g., altematingly. Binder pair 108 is the same as that
discussed earlier in connection with FIG. 12A; therefore, its description will
not be repeated here. As shown in FIG. 18B, binder pair 670 contains yarns
665 and 675. In the repeat pattern shown, yarn 665 travels above yarns 1 and
2, then passes below warp yam 3, travels above yams 4, 5 and 6, and then
interweaves top layer yarns 17-20 as shown. Yarn 675 interweaves yarns 11-
15, then travels above yarns 6 and 7, contours below yarn 8, and travels above
yams 9 and 10 to complete the repeat pattern. The binder pairs 108 and 670
may be used within fabric 680 interspersed with weft yarns such as those
shown in FIG. 2, or with those shown in FIG. 6, to form the composite fabric
680.
Referring now to FIG.19, another binder pair, 730, in accordance with
the invention is illustrated in a cross-sectional view, which forms a part of
a
composite fabric 700. Binder yarns 710 and 720 together comprise binder pair
730, which likewise binds together the yarns of paper side layer Li and wear
(machine) side layer L2. Binder pair 730 can also be considered to provide a
combination of the double knuckle structure of the binder 30 described above
and the DCP binders also described above. The shown pattern of binder pair
730 can be a repeat pattern which repeats in the CD direction. Yarn 710 forms
a double knuckle DK around yarns 3 to 5, and this double knuckle affords the
advantages mentioned earlier. Yarn 720 also forms a double knuckle DK,
around warp yams 8 and 10. Additionally, the co-location of binder yarns 710
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and 720 at locations above warp yarns 11 and 17, for example, renders the
binder pair a DCP-type binder with the attendant advantages. Note that yarn
720 drops sharply from above warp yarn 17 to below warp yarn 8, which
results in a further minimization of the internal float of that binder yarn.
As in
the case of binder pair 630, binder pair 730 can be implemented in a
composite fabric interspersed with other binders, such as with binder pair 30
of FIG. 1 (or 17B), or any of those shown in FIGS. 11 through 18.
Alternatively, binder pair 730 can be utilized as the' sole binder type of
fabric
700. As in the cases above, the binder pair of FIG, 19 is employed
interspersed with non-binder weft yarns (not shown) in fabric 700, such as
those depicted in FIG. 2 or FIG. 6.
It is further noted that as a further variation to the embodiments
described hereinabove, a number of the binder pairs within a fabric may be
woven such that the two yarns within such pairs are arranged in the same side
by side (or straight) manner for all such binder pairs. Additionally, a number
of the binder pairs within the fabric may be woven such that the two yarns
within such pairs are arranged in alternating or reverse side by side manner.
As an example, in the above-described fabrics having SSB binder pairs, the
SSB`binder pairs may be arranged so as to be straight or reversed.
Furthermore, although embodiments of the present invention have
been described as having a binding pair consists of CD yarns which pass over
one or two MD yams on an outer surface of the paper side layer, the present
invention is not so limited. That is, other arrangements may also be utilized.
For example, there may be CD yams which pass over more than two MD
yarns on an outer surface of the paper side layer within a repeat pattern. As
another example, the binder pair may include two MD yarns which pass over
one or more same CD yams within a repeat pattern. As still another example,
the binder yams may pass over one or more same CD (or MD) yams on an
outer surface of the machine side layer within a repeat pattern.
Additionally, although the present invention has been described as
usable for the papermaking process, the present invention is not so limited.
That is, the present fabric may be utilized for other uses.
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Application No. 2,509,067 Attorney Docket No. 17648-88
The fabric according to the present invention may comprise
monofilament yarns. The CD yarns may be polyester monofilament and/or
some may be polyester or polyamide. The CD and MD yams may have a
circular cross-sectional shape with one or more different diameters. Further,
in addition to a circular cross-sectional shape, one or more of the yarns may
have other cross-sectional shapes such as a rectangular cross-sectional shape,
elliptical or another non-round cross-sectional shape.
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