U.S. patent application number 12/600187 was filed with the patent office on 2011-01-27 for alternate twist ply yarn with low residual twist.
This patent application is currently assigned to DREXEL UNIVERSITY. Invention is credited to Donia Elkhamy, Frank Ko, Peter Popper, Paul Yngve.
Application Number | 20110016841 12/600187 |
Document ID | / |
Family ID | 40122149 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110016841 |
Kind Code |
A1 |
Popper; Peter ; et
al. |
January 27, 2011 |
ALTERNATE TWIST PLY YARN WITH LOW RESIDUAL TWIST
Abstract
ATP yarns having high twist efficiency (low residual twist) as
well as methods for increasing the self plying action that occurs
in ATP yarn processing. The self plying action and the ATP yarn
structure may be improved by increasing the convergence angle of
the singles twist yarns to above 50 degrees (compared to current
values of 0 to 35 degrees). The increased convergence angle permits
an increase in the ply twist above the level possible by self
plying alone. This results in a yarn with reduced residual singles
twist. An array of singles torque jets and an optional ply torque
jet has been developed to achieve a high convergence angle. The
angle between the singles torque jet axes can be varied from 0 to
180 degrees.
Inventors: |
Popper; Peter; (Wilmington,
DE) ; Elkhamy; Donia; (Erie, PA) ; Yngve;
Paul; (Prosperity, SC) ; Ko; Frank;
(Vancouver, CA) |
Correspondence
Address: |
KNOBLE, YOSHIDA & DUNLEAVY
EIGHT PENN CENTER, SUITE 1350, 1628 JOHN F KENNEDY BLVD
PHILADELPHIA
PA
19103
US
|
Assignee: |
DREXEL UNIVERSITY
PHILADELPHIA
PA
|
Family ID: |
40122149 |
Appl. No.: |
12/600187 |
Filed: |
May 16, 2008 |
PCT Filed: |
May 16, 2008 |
PCT NO: |
PCT/US08/63839 |
371 Date: |
October 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60938803 |
May 18, 2007 |
|
|
|
Current U.S.
Class: |
57/204 ;
57/293 |
Current CPC
Class: |
D02G 3/286 20130101 |
Class at
Publication: |
57/204 ;
57/293 |
International
Class: |
D02G 3/28 20060101
D02G003/28; D02G 1/20 20060101 D02G001/20; D01H 7/46 20060101
D01H007/46 |
Claims
1. An alternate twist ply yarn with a twist efficiency greater than
0.70.
2. An alternate twist ply yarn as claimed in claim 1, with a twist
efficiency of 0.75 to 1.25.
3. An alternate twist ply yarn as claimed in claim 1, with a twist
efficiency of 0.85 to 1.15.
4. An alternate twist ply yarn as claimed in claim 1, with a twist
efficiency of 0.95 to 1.05.
5. A method for making the yarn of claim 1 comprising the steps of:
twisting singles in lengthwise alternating directions using a
convergence angle of at least 50.degree.; and bonding yarns at a
twist reversal point.
6. A method as claimed in claim 5, wherein the convergence angle is
50-180.degree..
7. A method as claimed in claim 5, wherein the convergence angle is
70-150.degree..
8. A method as claimed in claim 5, wherein the convergence angle is
90-120.degree..
9. A method as claimed in claim 5, wherein at least one yarn ply
torque jet is employed in said twisting step.
10. A method as claimed in claim 9, wherein at least two singles
torque jets are employed in said twisting step.
11. A yarn torque jet assembly comprising at least two singles
torque jets and wherein an angle between axes of two of said
singles torque jets is from 0-180.degree..
12. A yarn torque jet assembly as claimed in claim 11, wherein the
angle between axes of at least two of said singles torque jets is
from 50-180.degree..
13. A yarn torque jet assembly as claimed in claim 11, wherein the
angle between axes of at least two of said singles torque jets is
from 70-150.degree..
14. A yarn torque jet assembly as claimed in claim 11, wherein the
angle between axes of at least two of said singles torque jets is
from 90-120.degree..
15. A yarn torque jet assembly as claimed in claim 11, further
comprising a guide which ensures that a yarn convergence angle is
different from the angle between the axis of said at least two
singles torque jets.
16. A yarn torque assembly as claimed in claim 11, further
comprising a ply torque jet located downstream of said at least two
singles torque jets.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to alternate twist ply yarns
(hereinafter "ATP yarns"), methods for manufacturing alternate
twist ply yarns and to apparatus used in the manufacturing
methods.
[0003] 2. Description of the Related Technology
[0004] ATP yarns can be produced at much higher rates, for example,
greater than ten times as fast as conventional ply yarns that do
not alternate the twist direction. However, ATP yarns suffer from
several problems that limit their use. Most significant is the
excessive level of residual singles twist (typically the twist
efficiency for ATP yarns is about 0.65). Conventional
unidirectional twist ply yarns have zero residual twist (which
equates to a twist efficiency of 1). In ATP yarns, the residual
twist prevents the individual fibers from achieving their full bulk
because they are tightly held in the structure (see for example
FIG. 3B). In addition, in the case of carpet yarns, current ATP
yarns can only be used in loop pile constructions (less than half
of the United States carpet market). Cut pile carpets cannot now be
made successfully with these ATP yarns due to the low twist
efficiency of the ATP yarns.
[0005] Past attempts to reduce the residual twist have been
generally unsuccessful. In particular, although adding a ply torque
jet to the manufacturing apparatus and process to increase ply
twist did produce a reduction in residual twist, this reduction was
only by a relatively small amount. Thus, there is a need in the art
for a way to overcome the problem of low twist efficiency in ATP
yarns.
SUMMARY OF THE INVENTION
[0006] In a first aspect, the present invention relates to ATP
yarns having a high twist efficiency.
[0007] In a second aspect, the present invention relates to a
method for increasing the self plying action that occurs in ATP
yarn processing. The self plying action and the ATP yarn structure
may be improved by increasing the convergence angle of the singles
yarns to above 50 degrees. The increased convergence angle permits
an increase in the ply twist above the level possible by self
plying alone. This results in a yarn with reduced residual
twist.
[0008] In a third aspect, the present invention relates to an array
of singles torque jets, an optional ply torque jet and optional
other apparatus developed to achieve a high convergence angle. The
angle between the jet axes can be varied from 0 to 180 degrees and
the convergence angle is at least 50 degrees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 shows a schematic representation of an ATP apparatus
with a high convergence angle.
[0010] FIG. 2 shows an alternate twist ply (ATP) yarn.
[0011] FIG. 3A shows a balanced ply yarn with zero residual
twist.
[0012] FIG. 3B shows a ply yarn with a high amount of residual
twist (reverse twist direction as the ply twist).
[0013] FIG. 4 shows the portion of the ATP process in which the
yarns converge and self-ply was modeled mathematically. The force
and torque equilibrium equations are shown in FIG. 4.
[0014] FIG. 5 shows the results of the equations plotted in terms
of singles torque versus convergence angle with parameter ply
torque.
[0015] FIG. 6 shows a plot of ply twist versus singles twist with
and without a ply jet, using the procedure of comparative example
A.
[0016] FIG. 7 shows a plot of twist efficiency versus convergence
angle without ply torque along with a control test of the low
convergence angle ATP machine as obtained using the procedure of
Example 1.
[0017] FIG. 8 shows a plot of twist efficiency versus convergence
angle with added ply torque along with a control test run on the
low convergence angle ATP machine using the procedure of Example
2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The present invention relates to alternate twist ply (ATP)
yarns as shown, for example, in FIG. 2, as well as to methods and
apparatus for making ATP yarns. The following terminology is
employed in this application.
[0019] Twist--Turns/length along a singles or ply yarn,
[0020] Singles--A yarn that is twisted and then plied together with
other yarns by twisting in the opposite twist direction in order to
reduce or substantially eliminate residual singles twist.
[0021] Ply Yarn--A yarn made of two or more singles yarns. The
singles are individually twisted and then twisted as a bundle in
the opposite direction to form the ply yarn.
[0022] Balanced Ply Yarn--A ply yarn in which the singles twist
equals the ply twist, but wherein the singles twist is in the
opposite twist direction to the ply twist.
[0023] ATP--Alternate Twist Ply yarn. A ply yarn in which the twist
direction alternates along the length. This yarn is twisted in one
direction (typically for several feet) and then twisted in the
opposite direction. The yarn is usually bonded or entangled where
the twist reverses.
[0024] Self Ply--The process step in which twisted singles yarns
converge and rotate about each other to form a ply yarn.
[0025] Residual Singles Twist--The singles twist that remains in a
singles yarn after plying which does not equal the ply twist. For a
balanced ply yarn, since ply twist=singles twist, the residual
twist is zero. This occurs because each turn of ply twist untwists
a turn of singles twist. If the ply twist is less than the singles
twist, some residual twist will remain. Thus, the Residual Singles
Twist can be expressed as:
Residual singles twist=(twist imparted in the singles yarns-twist
in the resulting plied yarn) (Equation 1)
[0026] Twist efficiency--Twist efficiency is defined as the ratio
of ply twist to singles twist imparted in a ply yarn. The twist
efficiency may be determined by measuring the ply yarn twist and
singles yarn twist in the produced yarns using a standard twist
tester (e.g. ITC-5 hand operated unit). First, a 40 cm sample
length of yarn is placed between the two jaws of the twist tester.
A 5 g weight is applied to the test sample at the spring loaded
left, jaw, creating tension in the yarn. The counter dial is then
set to zero, and the crank handle is turned manually to unwind the
ply twist. The counter reading, which represents the ply twist in
turns per 40 cm, is then recorded. With the unwound ply yarn still
held between the jaws of the twist tester, one of the singles yarns
is cut and removed. The counter dial is then reset to zero and the
crank handle is turned in the opposite direction to unwind the
twist in the remaining singles yarn.
[0027] The twist in the singles yarn may be measured using the
Untwist-Retwist Method according to ASTM standard D1422-99. In this
method, the singles yarn is first untwisted. The twist is then
reinserted until the tension loaded left jaw returned to its
initial position. The counter reading is then recorded and divided
by 2 to determine the singles twist in turns per 40 cm. Yarn twist
efficiency is calculated using Equation 2. The yarn twist
efficiency of the ATP yarn was subsequently determined by
calculating the average twist efficiency of five samples.
[0028] In a balanced ply yarn, the Twist Efficiency=1. If the ply
twist is less than the singles twist, the twist efficiency will be
less than 1. If the ply twist is greater than the singles twist,
the twist efficiency will be greater than 1. The relationship
between Twist Efficiency and singles twist is:
Twist efficiency=(Ply twist/singles twist) (Equation 2)
The ATP yarn of FIG. 2 shows twist alternatives section 4 and a
bond section 5. FIG. 3A shows sections of alternating twist and
thus having a twist efficiency of 1. FIG. 3B shows a ply yarn with
a high amount of residual singles twist in the reverse twist
direction as the ply twist. A negative residual twist means the
singles twist is in the same direction as the ply twist--since both
the singles and the ply are twisted in the same direction. Yarns of
that type are produced by a process called Sirospun..TM.
[0029] Both Twist Efficiency and Residual Twist may be expressed as
a ratio or as a percentage. Both are measures of the same property
in slightly different terms and thus these terms may be used
interchangeably in this application.
[0030] BCF--Bulked continuous filament yarn. All fibers in this
yarn are crimped to increase bulk.
[0031] The present invention can be used to increase the self
plying action that occurs in ATP yarn processing. Known ATP yarns
typically suffer from a specific technical problem--excessive
residual twist of the singles yarns. This problem can be overcome
by modifying the yarn processing method and apparatus in accordance
with the present invention. The self plying action and the ATP yarn
structure can be improved by increasing the convergence angle 3 of
the singles yarns to above 50 degrees. Optionally, an additional
ply torque jet 1 can be added to assist plying. The increased
convergence angle 3 permits the ply torque jet 1 or other suitable
apparatus to increase the ply twist above the level possible by
self plying of parallel yarns alone. This results in a yarn with
reduced residual twist.
[0032] In one exemplary embodiment of the apparatus of the present
invention, an array of singles torque jets 2 and an optional ply
torque jet 1 was developed to achieve a high convergence angle 3.
The angle between the jet axes of the singles torque jets 2 can be
varied from (0 degrees--jet axis parallel--to 180 degrees--jets
facing each other). The convergence angle between the jet axes of
the singles torque jets 2 may be from 50 to 180 degrees, from 70 to
150 degrees, or from 90-120 degrees.
[0033] In another exemplary embodiment of the apparatus of the
present application, the ATP yarn manufactured according to the
method of the present invention, at high convergence angles 3 and
using helper jets, produces substantially high twist efficiency. By
increasing the ATP yarn convergence angle 3 to about 90 degrees and
using a helper jet, the ATP yarn may have a twist efficiency of at
least 0.70.
[0034] In all known ATP processes, the torque in the singles yarns
causes them to rotate around each other to form the ply yarn. But,
the amount of ply twist is not as high as the singles twist.
Consequently, all of the twist in the singles is not removed and
undesirable singles twist remains.
[0035] Adding a ply torque jet 1 to existing systems which
typically employ convergence angles 3 of 0-35 degrees, to increase
ply twist yields only a small improvement because only a small
amount of residual twist is removed by this measure. The reason for
this limited improvement was found to be a "singles twist
reduction" phenomenon. When torque is added to the ply yarns, the
geometry of the yarn path requires the singles torque to
drop--because of tension and torque equilibrium requirements. That
means that adding ply torque, although it can increase ply twist,
also reduces singles torque, the driving force for self plying. A
ply torque jet 1 added to a conventional system employing a
convergence angle 3 of 0-35 degrees thus causes two effects, one
advantageous and one detrimental.
[0036] FIG. 4 shows the yarn mechanics in the convergence zone
highlighting the two effects of a ply torque jet 1. The results of
this analysis were plotted in FIG. 5. These results confirm that if
the process is run at a high convergence angle 3, the detrimental
effect of the ply torque jet 1 is minimized while the benefits of
the ply torque jet 1 are still obtained. This is a useful feature
of the present invention.
[0037] The method and apparatus of the invention can be used to
produce an alternate twist ply yarn with a twist efficiency greater
than 0.70, more particularly, an alternate twist ply yarn with a
twist efficiency of 0.75 to 1.25, an alternate twist ply yarn with
a twist efficiency of 0.85 to 1.15, or an alternate twist ply yarn
with a twist efficiency of 0.95 to 1.05.
Basic Mechanical Action of Self Plying
[0038] The portion of the ATP process in which the yarns converge
and self-ply was modeled mathematically as shown in FIG. 4. The
force (Equation 3) and torque equilibrium equations (Equation 4)
used to quantify how increasing convergence angle 3 prevents the
ply torque jet from reducing torque on the individual singles
yarns:
T.sub.P=2T.sub.S cos .theta. (Equation 3)
.tau..sub.p+2.tau..sub.s cos .theta.-T.sub.SD.sub.S sin .theta.=0
(Equation 4)
Where .tau..sub.p,.tau..sub.s represents torque in singles and ply
yarn for opposite direction twists, T.sub.P,T.sub.S represents
tension in singles and ply yarn, .theta. represents half
convergence angle 3, and D.sub.S represents singles yarn diameter.
The torque on the ply yarn may be applied by a ply torque jet 1 (or
other suitable means) to increase ply twist. The torque in the
singles yarns is applied by the individual singles torque jets 2.
The singles yarn torque causes rotation and plying and the amount
of plying may be increased by the ply jet.
[0039] FIG. 5 shows the results of the equations plotted in terms
of singles torque versus convergence angle 3 with parameter ply
torque. For a given convergence angle 3, as the ply torque is
increased, the singles torque is reduced. This means that the basic
driving torque for the process is reduced when a ply jet 1 is
turned on. In other words, increasing the ply torque to achieve
more ply twist has the opposite effect as the singles torque is
reduced. In fact, it can be reduced so much that the singles torque
is in the opposite direction. (Yarns of that type can be made. They
do not alternate twist and are made in a completely different
way--the Sirospun.TM. process.)
[0040] The undesirable effect described can be overcome by
operating at a high convergence angle 3. Because of the non-linear
relation between the variables, at a high convergence angle 3, ply
torque can be added without driving the singles torque to low
levels that prevent self plying.
[0041] FIG. 1 shows a schematic representation of an ATP apparatus
with a high convergence angle 3. The singles jets twist downstream
(because the twist direction reverses in time cycles) and the ply
jet increases the ply twist from what it would be if only
self-plying occurred. The high convergence angle 3 is facilitated
by the angle between the jet axes. High convergence angle 3 might
also be achieved with parallel axis jets, but that would require
extensive rubbing on the jet wall and result in a relatively
inefficient torque application and thus is less preferred. Addition
of a small guide or guide pins downstream of parallel singles
torque jets 2 might also be used to increase the convergence angle
3. The guide or guide pins would fit between the singles yarns and
prevent them from converging at a low angle. Alternatively, high
convergence angles 3 can be achieved by deflecting yarns with
directed air flow. This flow can come from added air jets or from
the exhaust of the singles yarns jets. Yet another way of
increasing convergence angle 3 is to set the process parameters
(such as feed tension) to achieve a low singles yarn tension. At
lower tension, the convergence angle 3 increases. Other process
adjustments or combinations of the above could also increase
convergence angle 3. In each of these scenarios, the convergence
angle 3 between the axes of the singles torque jets 2 could, for
example, be anywhere in the range of 0-180 degrees with the other
means assuring the desired convergence angle 3 downstream of the
outlets of the singles torque jets 2 and upstream of the optional
ply torque jet 1.
[0042] One alternative to use of the optional ply torque jet 1 to
apply ply torque to the converging singles yarns would be the use
of rollers as in the conventional Repco process.
EXAMPLES
[0043] A number of experiments were conducted to demonstrate the
technology and the invention. Each will be described in detail
along with the method of measuring residual twist.
Method of Measuring Residual Twist
[0044] 1. Select a 20 inch length of ATP with twist in one
direction. [0045] 2. Using a standard twist counter and constant
tension, measure the ply twist (turns/2.54 cm). [0046] 3. When all
the ply twist has been removed, continue to grip the yarn and
remove all but one singles yarn (which will be restored to the
twist level it had before plying). [0047] 4. Measure the twist in
the remaining singles yarn (the point of zero twist corresponds to
the maximum untwisting length). [0048] 5. Calculate Twist
Efficiency as the ratio of ply to singles twist. [0049] 6. Convert
to Residual Twist, if needed, by Equation 1 given above.
[0050] On the Static Test Machine, the Twist Efficiency was
measured on photographs of the converging singles yarns and the
adjacent ply. Black tracer filaments were used to simplify
identification of singles twist.
Comparative Example A
Effect of Ply Jet on Residual Twist
[0051] A laboratory ATP machine was used with and without a ply
jet. Ply twist was measured for a range of singles twists and
plotted on a graph that indicates twist efficiency levels. In
addition, a static test machine was also used to prepare similar
samples. In the static test machine, yarns were put into a "Y"
configuration to simulate the actual process.
Key ATP Machine Conditions
[0052] Bonding method--ultrasonic bond
[0053] Twist reversal length--3 ft
[0054] Convergence angle--.about.35.degree.
[0055] Singles--Nylon BCF 1250 denier
[0056] Output--2 ply yarn
Static Test Machine Conditions
[0057] Convergence angle .about.35.degree.
[0058] Singles--Nylon BCF 1250 denier
[0059] Output--2 ply yarn
Results
[0060] Ply twist versus singles twist (with and without) ply jet is
plotted in FIG. 6.
[0061] Twist efficiency decreases as twist increase (a twist
efficiency of 100% corresponds to the ratio of ply twist/singles
twist equaling 1).
[0062] The static tester results are very close to those of the ATP
machine
[0063] Ply, jet increases Twist Efficiency (reduces Residual Twist)
by negligible amount
[0064] It was found that adding a ply, jet to a standard process
with low convergence angle does not significantly reduce residual
twist.
Example 1
Effect of a High Convergence Angle on Residual Twist
[0065] The purpose of this test was to evaluate the effect of
convergence angle on residual twist with and without an added ply
torque jet 1. The experiment was run on the Static Tester because
an ATP machine with the hardware needed for high convergence angle
was not immediately available. The Static Tester was qualified as
being a prototypic representation of the ATP machine in of
Comparative Example A.
Static Test Machine Conditions
[0066] Convergence angle--varied throughout experiment
[0067] Singles--Nylon BCF 1250 denier
[0068] Output--2 ply yarn
[0069] Ply torque--experiment run with and without
Results
[0070] Twist efficiency versus convergence angle without ply torque
are plotted in FIG. 7 along with a control test of the low
convergence angle ATP machine. The results show that higher
convergence angles improve twist efficiency by a relatively small
amount over the control system. A twist efficiency of 100%
corresponds to the ratio of ply twist/singles twist equaling 1.
[0071] Twist efficiency versus convergence angle with added ply
torque are plotted in FIG. 8 along with a control test run on the
low convergence angle ATP machine. The results show a very
significant increase in twist efficiency relative to the control
experiment. Levels well over 1 were reached.
[0072] This experiment demonstrates that twist efficiency can be
increased to required levels (and residual twist can be removed) by
operating the process with a ply jet and a high convergence angle
of 100-180 degrees.
Example 2
Operating Test for High Convergence Angle Singles Torque Jets
[0073] The purpose of this example was to demonstrate the
operability of the torque jet assembly of the present
invention.
Jet Description
[0074] Two singles torque jets mounted on a plate that permits
their axes to be angled up to 180.degree..
Test
[0075] Install the jet in ATP machine
[0076] Yarn speed--400 yards/minute
[0077] Singles yarns--two 1245 denier Nylon 6,6 BCF
[0078] Air pressure--40 to 90 psig
[0079] Evaluate operability, no attempt to produce ATP
[0080] Yarn feed geometry--parallel yarns into jets
Results
[0081] Yarns ran well through the jets at 0, 50, 90.degree.
[0082] A new angled jet device was successfully fabricated and
operated on an ATP machine at 400 yards/min with angles up to
90.degree.. ATP yarns were not made in this example.
Example 3
Effect of High Convergence Angle and Helper Jet on Twist
Efficiency
[0083] The purpose of this experiment was to evaluate the effect of
convergence angle on the residual twist of yarn with and without an
added ply torque jet.
Test
[0084] The following is a list of equipment and materials used to
conduct the experiment:
Drexel ATP Lab Machine
[0085] Two 1245 BCF nylon feed yarns Main torque-jet pressure 30
psi Singles yarn tension 34 g Helper torque-jet pressure 75 psi
Results
[0086] FIG. 9 shows the measured twist efficiency for ATP yarn with
and without a ply torque jet over a range of convergence angles. As
shown by FIG. 9, using a helper torque-jet substantially improves
twist efficiency. Furthermore, increasing the convergence angle,
preferably to about 90 degrees between yarns, also substantially
enhanced twist efficiency when a helper jet is used, but increasing
the convergence angle was found to decrease efficiency without a
helper jet. Based on this experiment, the highest twist efficiency,
about 78%, was achieved at a high convergence angle of about 90
degrees and by using a helper torque-jet.
Example 4
Examples of an ATP Yarn Having a High Twist Efficiency
[0087] The twist efficiency for an ATP yarn manufactured according
to the method of the present invention, at high convergence angles
and using helper jets, was investigated. By increasing the ATP yarn
convergence angle to 90 degrees and using a helper jet, it was
possible to produce an ATP yarn with a twist efficiency of at least
70%.
Results
[0088] Table 1 shows the twist efficiency of the ATP yarn of the
present invention in comparison to two control ATP yarns.
TABLE-US-00001 TABLE I Process Conditions Convergence Angle Twist
Efficiency Machine Between Yarns Helper Jet (%) Commercial
Approximately None 66 Process (Belmont Zero Textile Machine) Drexel
Lab Approximately None 59 Machine Zero Drexel Lab 90 Degrees On 78
Machine
Test
[0089] The twist efficiency was determined by measuring the ply
yarn twist and singles yarn twist in the produced yarns using a
standard twist tester (e.g. ITC-5 hand operated unit). First, a 40
cm sample length of ATP yarn located between two successive bonds
in the ATP yarn was placed between the two jaws of the twist
tester. A 5 g weight was applied to the test sample at the spring
loaded left jaw, creating tension in the ATP yarn. The counter dial
was then set to zero, and the crank handle was turned manually to
unwind the ply twist. The counter reading, which represents the ply
twist in turns per 40 cm, was then recorded. With the unwound ply
yarn still held between the jaws of the twist tester, one of the
singles yarns was cut and removed. The counter dial was then set to
zero again, and the crank handle was turned in the opposite
direction to unwind the twist in the remaining singles yarn. The
twist in the singles yarn was measured using the Untwist-Retwist
Method according to ASTM standard D1422-99. In this method, the
singles yarn was first untwisted. The twist was then reinserted
until the tension loaded left jaw returned to its initial position.
The counter reading was then recorded and divided by 2 to determine
the singles twist in turns per 40 cm. Yarn twist efficiency was
calculated using Equation 2. The yarn twist efficiency of the ATP
yarn was subsequently determined by calculating the average twist
efficiency of five samples.
[0090] For illustrative purposes, the principles of the present
invention are described by referring to various exemplary
embodiments thereof. Although the preferred embodiments of the
invention are particularly disclosed herein, one of ordinary skill
in the art will readily recognize that the same principles are
equally applicable to, and can be implicated in other compositions
and methods, and that any such variation would be within such
modifications that do not part from the scope of the present
invention. Before explaining the disclosed embodiments of the
present invention in detail, it is to be understood that the
invention is not limited in its application to the details of any
particular embodiment shown. The terminology used herein is for the
purpose of description and not of limitation. Further, although
certain methods are described with reference to certain steps that
are presented herein in certain order, in many instances, these
steps may be performed in any order as may be appreciated by one
skilled in the art, and the methods are not limited to the
particular arrangement of steps disclosed herein.
* * * * *