Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE I~lVENTION
Thi~ invention relate~ generally to narrow weaves and
more particularly to a ~heer elastomeric woven fabric.
In the field of narrow bands or tapes containing
elastomeric or rubber threads, the elastomeric threads are
generally covered so as to retain their position in the final
wea~e in use as well as over the lifetime of the fabric. The
multiple washings over a lifetime have a tendency to cause the
elastomeric threads to move relative to the remainder of the
threads and thus provide an unattractive and unuseable element
of a piece of apparel. By using wrapped elastomeric thread~,
the fabric may be formed by weaving relatively low wefts per ;
inch, such as 30 wefts per inch. This reduction in the weft~
per inch makes the wo~en fabrics co~ercially competitive in
~pite of the increased cost of the covered elastomeric thread.
When forming narrow bando, tapes, or ~trap~ from
uncovered elastomeric or rubber threads, the number o$ wefts
per inch must be increAsed to hold the bare elastomeric thread~
in plac~ ln the woven fabric. This generally includes weaving
20 at 50-60 weft3 per inch aepending upon the density or number of
; ends. Though b~ing relatively cheaper than the amount of
materials being used, the increased we~ts per inch increases
the C09t of production.
Wrapped ela3tomeric threads may be single or double
wrapped with a second material or yarn. Single and double
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wrapped elastomeric yarns are generally balanced, but have a
tendency when unbalanced or un~table to turn, twist, and form
extending loops of the wrapped material. The unstable condition
of the wrapped elastomeric yarn also causes narrow tapes formed
with the elastomeric band to twist or turn or not to lie flat.
Wrapping operations are expensive since they re~uire
separate machinery to wind the thread~, unwind the thread~,
wrap the threads, and rewind the threads, as well as space and
operating time. The single and double wound elastomeric threads
of the prior art are generally bulky since they are tightly
wrapped to keep the elastomeric thread under tension and to
counteract or restrain any twisting or buckling of the elasto-
meric thread. The wrapping yarn is generally twisted so as to
bring forces to bear on the elastomeric yarn. It is this twist-
ing that sets up the unstable condition of the wrapped elasto-
meric thread which produces the undesirable results in the final
woven product.
Thus, there exists a need for making a sheer,
inexpensive, narrow elastomeric fabric.
SUMM~RY OF THE INVENTION
The pre~ent invention relates to a narrow woven elas-
tic fabric. The warp of the fabric includes a plurality of
ela3tomeric threads separated fxom each other by a plurality
of high shrink non-elastic synthetic threads which are prefer-
ably made of nylon or polyester. The two edge warp threads are
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elastomeri~ and are loo~ely wrapped with a heat set yarn to
increase the hold of these edge elastomeric warp threads. The
edge elastomeric threads are under the same tension as the other
elastomeric threads to assure the stability of the woven fabric.
A high shrin~ synthetic weft thread is interwoven with the warp
threads. The process includes the step~ of providing the warp
threads from a plurality o~ supply elements to the loom and
wrapping the two edge warp elastomeric threads between the
supply and the loom with texturized, heat set synthetic yarn,
for example, polyester yarn. The weft is woven at a lcw weft
count for example 25-35 wefts per inch. The non-elastic warp
threads and the weft thread are preferably continuous multi-
filament yarns. The final woven product is heat treated at a
temperature sufficient to cause the high shrink weft and warp
threads to shrink 80 as to further bind the elastomeric threads.
The temperature i8 not sufficient to heat set the elastomeric
threads, but the elastomeric thread assume4 a corrugated shape
which increases the hold of the ela~tomeric thread in the final
woven product.
The machinery needed to provide the proper tension of
the elastomeric thread from the supply elements to the loom as
well as the rate of wrapping of the wrap yarn include~ mechanically
interconnecting the drive of the loom with the drive of the
wrapping device and the positive feed mechanism for the elasto-
meric threads. The elastomeric threads are driven or let-off
the spool by interconnected or synchronous feed rollers which
engage the elastomeric material on the rolls and control or
synchronize let-off.
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An object of the invention i9 to provide a sheer,
long-lasting, narrow elastomeric fabric, tape, or band.
Another object of the invention is to provide a
narrow elastomeric fabric requiring low wefts per inch of
weaving operation without reducing the life of the fabric.
A further object of the invention is to provide a
stable stretch fabric having covered and bare elastomeric
threads.
According to the above objects, from a broad aspect,
the present invention provides a narrow woven fabric comprising
a plurality of shrunk non-elastomeric warp threads. A plurality
of bare elastomeric warp threads are separated by the shrunk
warp threads. A pair of elastomeric threads form the edge warp
threads, each of the edge warp threads having a heat set yarn
loosely wrapped thereon. A shrunk non-elastomeric weft thread
is also provided in the fabric.
Other objects, advantages, and novel features of the
pre~ent invention will become apparent from the following
detailed description of the invention when considered in con-
junction with the accompanying drawings in which:
Figure 1 is a cro~ ectional view of a narr~w woven
fabric incorporating the principles of the pre~ent invention.
Figure 2 i~ a cross-sectional view of the fabric of
Figure 1 taken along lines 2-2.
; 25 Figure 3 is a section of elastomeric thread with the
polyester loosely wrapped thereon.
Figure 4 i3 a side elevation of the interrelationship
- of the thread supply, wrapping device and loom.
10~ 3
Figure 5 i~ a front view of the thread ~upply and
wrap~ping device taken along line~ 5-5 of figure 4.
Figure 6 is a diagrammatic perspective of the thread
supply, wrapping device and loom drives.
S DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fabric illustrating the concepts of the present
invention is illustrated in Figures 1 and 2. The warp is made
up of a plurality of warp threads, including high shrink back
threads 10, high shrink binder threads 12, bare elastomeric
threads 14, and covered elastomeric edge warp threads 16. A
heat set synthetic yarn 18 is loo~ely wrapped around the edge
elastomeric warp threads 16 to increase their hold within the
woven fabric. A ~igh shrink weft thread 20 is interwoven with
the warp threads. The specific fabric illu~trated in Figures
~5 1 and 2 includes eight kack threads 10, sixteen binder threads
12, and nine elastomeric threads 14, 16. The back threads 10,
as illu~trated in Figure 2, are interwoven with the weft threads
20 every fourth weft. The non-elastic warp threads 10 and 12
and weft thread 20 may be any high heat shrinkable synthetic
'0 yarn, preferably selected from nylon or polyester, and heat
set ~ynthetic wrapping yarn 18 i~ preferably polyester.
As will be evident from the detailed analy~is of the
method, it i important that the majority of the warp threads 12
and the weit thread5 20 be heat-~hrinkable threads to diminish
'5 the weave and increase the bind or holding power on the elasto-
meric threads 14 and 16~ Similarly, it is es~ential that the
wrapping thread 18 he pre-heat ~et ~o as to not be afiected by
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the subsequent heat treatment and that the ela~tomeric threads
14 and 16 be capable of forming corrugationq during ~he heating
process. This is also important to increase the holding power
of the fabric on the elastomeric thread~.
9 In a specific embodiment of the present invention,
the elastomeric threads 14 and 16 were spandex having a 1120
denier; the warp threads 10 and 12 were thirty-four filament
140 denier nylon, the weft thread 20 was a thirty filament
150 denier polyester, and the wrapping yarn 18 was a textured,
heat set 150 denier polyester. It i5 considered quite desirable
that the high shrink warp and weft threads be continuous filament.
By viewing the structure of Figure 1, it is seen that
the interior warp elastomeric threads 14 are bare and the
exterior or eage elastomeric warp threads 16 are wrapped. The
exterior elastomeric threads must be wrapped since the weft
thread wrapping around the edge warp thread 16 produces a
tunneling effect ~uch that the weft threads cannot bind or hold
the elastomeric edge warp thread 16 sufficiently to hold them
from ~lipping in the fabric. A section of the wrapped elasto-
meric thread 16 having the heat set polyester yarn 18 loosely
wrapped around it i8 illustrated in Figure 3. ~he wrap i~
sufficiently tight to increase the coefficient of friction of
the elastomeric thread without reducing or restricting its
diameter.
The method of thi~ invention needed to produce the
novel fabric includes controlling the let-off of bare elasto-
meric threads as warp threads into a loom and 1005ely wrapping
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heat set yarn onto the edge elastomeric warp threads between
the supply and the loom. The loose wrap is possible since the
elast:omeric thread is under tension from its supply directly
into the loom and onto the take-up roll of the loom whereas
with pre-wrapped elastomeric yarn the wrap must be tight to
prevent curling, looping, and buckling which is present when
the wrapped elastomeric thread is wound on a supply cone and
unwound in use on the loom. Also, it is difficult to use
pre-wrapped elastomeric threads in combination with bare
elastomeric threads becau~e it is necessary to control the
tension on the elastomeric threads during wrapping relative to
the tension on the bare threads during weaving (preferably the
tensions are about equal) in order to obtain a stable fabric
which will lie flat. The wrapping yarn is applied without twists
and conequently the resulting structure produces an elastomeric
yarn which i8 stable and not under any twi~t or tension. The
ela3tomeric warp yarns are separated by non-elastomeric heat
~hrinkable synthetic warp yarns, preferably made of nylon or
polyester and preferably the weft yarn i~ interwoven t,herewith
at a low weft per inch. Generally, a weft count between 25 and
35 wefts per inch i~ sufficient to initially hold the elastomeric
yarns in position in the woven fabric on the take-up roll.
The woven fabric is then heat treated at between
140_1soC. to shrink the heat shrinkable warp and weft threads
to tighten the weave and to bind the elastomeric warp threads.
With the contraction of the weave pattern, the ela~tomeric
thread~ increase their corrugation or buckles. The temperatures
io~s;~
are not sufficient to cau~e heat setting of the elastomeric
threads. By wrapping the elastomeric threads with a heat set
yarn, a further reduction of the denier of the elastomeric
thr~_ads i-~ not produced by the heat treatment. In a typical
procedure, heat treatment is carried out on a Carroll calender
using steam heated drums with a steam pressure of 40-65 pounds
per square inch. The fabric may be treated with a wax softener
and a resin prior to heat treatment to improve the hand or
finish of the final woven product.
Since some of the bare elastomeric threads are being
simultaneously wrapped and woven, it i9 essential that the
let-off or feed mechanism for the elastomeric thread be syn-
chronized with the weave or loom operations so as to provide
the proper tension on the elastomeric threads during the combined
operations and maintain them equal to the tension on the bare
elastomeric threads~ This is even more critical in a needle
loom which operates at a greater rate of speed than than the
standard gang looms. Although the fabric and method of the
present invention has been produced on both looms, it.is
prefexably performed on a needle loom. The apparatus as illustrated
in F$gures 4, 5, and 6 i9 a needle loom, for example, a Crompton
& Knowle~ model NL-7.
Mechanisms illustrated in Figures 4 and 5 include
a loom 21, a driven creel 22, a yarn creel 24 and wrapping
device 26. The yarn creel 24 include~ a plurality of rolls
or cones 28 of non-elastic, heat shrinkable synthetic threads
for the warp threads and a cone 30 of heat shrinkable synthetic
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thread for the weft thread of each fabric woven. The cones
are supported on ~pindles 32 connected to uprights 34 which
are secured to the frame 36 of the yarn creel. The frame is
held above the floor by a pair of uprights 38. A guide 40
5 i8 provided at the front of frame 36 to guide or direct the
warp threads into the warp of loom 21. The non-elastic warp
and weft thread~ are let-off a~ needed by the ten~ion exerted
by the loom take-up roll and the shuttle or needle of the weft
re~pectively. Tension devices, not shown, provide the desired
ten~ion on the warp thread~ from cones 28.
The driven roller creel 22 includes a plurality of
non-slip roller~ 42 including shafts whose outer ends are
journalled in supports 44 and are interconnected by sprockets
and chains 46. The interconnection of the drive rollers by
chain~ synchronizes the rotation 90 as to drive the surface of
the ela3tomeric thread~ to control or synchronize the let-off
and consequently maintain equal tension on all ela~tomeric
thread~ whether to be wrapped or not. A plurality of roll~
of elastomeric yarn 48 are ~hawn resting on their face between
two non 81ip rollers 42. The elastomeric threads leave the
supply rolls 48 and traverse guide rollers 50 on their way to
the loom 21. A main ~haft 52 (Figure 5) i~ mounted to the
driven creel 22 and includes a sprocket 54 to receive chain
; drive 56 ~rom the loom and is interconnected to the synchronous
chains 46 of the non-~lip roller drives by a chain and ~procket
5~.
Between the driven creel 22 for the elastomeric
threads and the loom 21 is a wrapping device 26. Mounted to
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support 60 are ~pindles 62 having bobbins 64 of the heat -~et
wrap mounted thereon. A spring 66 biases a flyer wire 68 into
a top 70. The to-be-wrapped elastomeric thread traverses the
center of the wrapping device 26 or spindle 62 and has preferably
a texturized heat ~et polyester yarn wrapped thereon by flyer
wire 68. The wrapping device 26 is driven by belts and gears
72 which are interconnected to the loom drive by chain 74.
Four wrapping devices 26 (without the uprights for support 60)
are illu~trated in Figure 5 Rince loom 21 is capable of weaving
two fabrics Rimultaneously.
As illustrated in Figure 4, a guide frame 76 receives
the non-elastic warp threads from yarn creel 24 and the elasto-
meric threads from the driven creel 22 to provide the warp for
the loom 21. Ihe weft thread is received by a driven roller 78
and transmitted to the needle or shuttle. Roller 78 is inter-
connected by chain 80 to shaft 82 which also drives the chain 74
which drives the wrapping device 26.
~he interconnection of the drive of the loom and the
~unctional element of the loom 21 with the wrapping devices 26
and the driven creel 22 for the elastomeric threads i9 illustrated
diagrammatically in Figure 6. The main motor 84 ha~ a drive
shaft 86. By appropriate gears the take-up roller 88 is con-
nected to shaft 86 by its shaft 90 and chain and sprocket 92.
Shaft 90 i~ also connected to the feed roller drive shaft 52
by chainq 93, gear box 94, and chain 56. The gear box 94 is
sufficient to interconnect or synchronize the drive or rotation
of the take-up roll 88 and the drive for the rollers 42 for the
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ela~tomeric threads. Thu~, the tension on the threads can be
morle uniformly controlled for wrapping and sub~equent warp
structure in the loom. Motor drive shaft 86 is also connected
by ~hain and sprockets 96 to a shaft 98 which drives the shed
cam mechanism 100. Also driven by shaft 98 through chain and
sprockets 102 is shaft 82 which drives through chain 80 the
weft roller 78 and drives through chain 74 the wrapping gear 72.
Thus, the low speed take-up reel drive i8 used to drive the
let-off for the elastomeric thread feed and the high speed
shed cam drive i8 used to drive the high speed weft feed roller
and the wrapping device.
Although Figure 6 illustrates a mechanical synchroniza-
tion of the respective drives, obviously individual motor drives
may be provided using a system of electronic or electrical
synchronization. Since the ~hed cam drive is available as well
a~ the take-up roll drive, the mechanical implementation is
considered inexpensive and provides the performance of control
characteristics.
The method and apparatus of the present invention
reduces the coqt of manufacture ~y reducing the meahanical work
done and the amount of materials used. By the use of synthetic
elastomeric threads instead of rubber, needle cutting is
eliminated and the fabric formed is sheer. The use of threads
of heat shrinkable material such as nylon and polyester al50
provide the heat characteri~tics desired whereby the final heat
treatment shrinks these threads to tighten the weave and prevent
31ippage of the elastomeric threads without the use of prewrapped
~0893~;~
ela~tomeric threads except at the edges of the fabric. The
pres,ent materials and method provide a sheer elastic band with
the ,ability to withstand repeated washings.
From the preceding description of the preferred
embodiments, it is evident that the objects of the invention
are obtained, and although the invention has been described
and illustrated in detail, it i8 to be clear that the details
are intended for illustrative purposes only and are not to be
taken by way of limitation. If desired for certain end uses,
more elastomeric threads than the edge elastomeric thread~ may
be wrapped between the Yupply and the loom. The spirit and
scope of the invention are to be limited only by the terms of
the appended claim~.
This application is a division of application
Serial No. 288,296, filed October 7, 1977.
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