Patent Application
20080283653
The present invention relates to yarn or fiber unwinding devices, and more specifically to a method and apparatus designed to continuously deliver as-spun over-end-take-off yarn to downstream manufacturing equipment at targeted average tension levels and minimal tension variations of a plurality of elastomeric yarns or fibers being transported to the downstream manufacturing equipment. It should be noted that the terms “yarn,” “thread” or “fiber” are used interchangeably throughout this document.
The most common method of unwinding yarn, thread or fiber from a cylindrical mandrel (or “tube” or “package”) in manufacturing processes is referred to as “rolling takeoff”. When the package is exhausted the empty mandrel must be removed and a new package installed. This operation requires shutting down the manufacturing line causing unproductive downtime.
Another background art example of a method for unwinding yarns from package(s) held on a creel is the over-end-take-off (OETO) method. The OETO method allows for continuous operation of the unwinding process since the terminating end of the yarn of an active package is attached to the leading end of the yarn of a standby package. In the OETO method, after the active package is fully exhausted, the standby package becomes the active package. However, a drawback of the OETO method is that unacceptable yarn tension variations can occur during the unwinding process.
In a background art example of a system and apparatus that implements the OETO method, elastomeric fibers are passed through the system before being fed to a manufacturing line. This background art OETO system has a rack structure that holds the creels of active packages and standby packages, a relaxation section and motor driven nip rolls. The relaxation section is located between an active package and the nip rolls of the OETO system. The relaxation section helps to suppress the unacceptable yarn tension variations discussed above by providing some slack in the yarn being unwound.
However, background art OETO systems that include such a relaxation section have problems with fibers or yarns that exhibit high levels of tack (i.e., yarns having particularly high cohesive forces). Moreover, yarns with high levels of tack also display unusually high variations in frictional forces and yarn tension levels as the active package is unwound from the creel.
In addition, the slack in the yarn provided by the relaxation section can vary, and excess yarn can be unwound from the active package. This excess yarn can be drawn into the nip rolls and wound upon itself leading to entanglement or breakage of the yarn. Use of yarns with high levels of tack further contributes to the possibility of the excess yarn adhering together and adhering to the nip rolls. The entanglement or breakage of yarns during the unwinding process requires the manufacturing line to be stopped, delays the unwinding process and increases the cost of manufacturing.
Background art OETO apparatus are typically configured such that the yarn horizontally traverses the relaxation section. In this configuration, the yarn travels through nip rolls with axes that are vertical. However, with such a vertical configuration for the axes of the nip rolls, the yarn located in the relaxation section between the active package and the nip rolls tends to sag. As a result, the yarn position on the nip rolls can become unstable, and interference and entanglement can occur between adjacent yarns. Each of these problems would require the manufacturing line to be stopped.
Furthermore, some manufacturing applications (e.g., diaper manufacturing) require the use of as-spun fiber that is substantially finish-free. Such finish-free yarns also exhibit the problems associated with high levels of tack discussed above.
The problems discussed above make applying OETO methods and apparatus particularly difficult when processing yarn with a high level of tack. Background art OETO apparatus have attempted to address these problems in the unwinding process by: (1) using yarns with anti-tack additives applied prior to winding; and/or (2) using rewound packages, where an active package is unwound and then rewound on a different creel to create a rewound package. Both of these approaches add additional expense to the manufacturing and unwinding processes.
As a result of the problems discussed above, OETO apparatus of the background art have been designed to take into account the difficulties due to the relaxation section, high levels of tack and breakage in yarns unwound with the OETO method. As an example, U.S. Pat. No. 6,676,054 (Heaney et al.), which is wholly owned by the assignee of the present application, discloses an OETO method and apparatus for unwinding elastomeric fiber packages with high levels of tack from a package. In particular, the OETO apparatus of Heaney et al. proposes that a minimum distance exists between a fiber guide and the fiber package. Heaney et al. states that minimum distances less than 0.41 meter can result in undesirably large tension variations. These variations can cause process control difficulties and can also lead to yarn breakages.
Further, Heaney et al. states that distances longer than 0.91 meter make the unwinding equipment less compact and ergonomically less favorable. As the level of tack exhibited by the fiber increases, the minimum allowable distance, d, increases. For yarns with tack levels greater than about 2 grams and less than about 7.5 grams, d is preferably at least about 0.41 meter; and for fibers with tack levels greater than about 7.5 grams, d is preferably at least about 0.71 meter. In view of such minimum distance requirements for high tack yarns, OETO apparatus typically require a frame with a large footprint that can take up significant floor space in a manufacturing environment. Additional examples of background art references are given by U.S. Patent Application Publication Nos. US 2005/0133653 (Heaney et al.) and US 2006/0011771 (Manning, Jr. et. al.), each of which is incorporated by reference herein.
Therefore, there continues to be a need in the art for an OETO apparatus for unwinding yarns with high levels of tack that avoids the problems of entanglement, breakage, larger equipment footprint and increased manufacturing costs as compared to the methods and apparatus of the background art. Processing high tack, elastomeric threads or fibers is particularly problematic when such as-spun thread or fiber is substantially finish-free, as is common for the elastomeric threads or fibers used to make diapers and other personal care products. Hence, there remains a need in the art for an OETO apparatus for unwinding yarns with or without anti-tack additives that can be implemented in a relatively small footprint. Therefore, a fast and reliable method of unwinding and feeding high tack elastomeric thread or fiber from a package to a manufacturing system is still needed in the art.
One embodiment of the invention is an OETO creel system, comprising: a support frame with a plurality of thread guides; at least one pivoting leg connected to the support frame; a plurality of package holders affixed to the at least one pivoting leg with each holder configured to hold one or more packages of thread, with each said package of thread located on a rotational axis configured to allow the thread to unwind through one of the plurality of thread guides; and a plurality of drive and tension control apparatus connected to the support frame, with each of said apparatus configured to unwind a thread from one of the plurality of packages of thread.
In the embodiment of the OETO creel system discussed above, each drive and tension control apparatus comprises: a pretensioner and associated guide roll configured to guide the unwinding thread through a thread path of the drive and tension control apparatus; at least one eyelet configured to prevent tangles of the thread; a horizontal driven take-off roll configured to move the thread through the drive and tension control apparatus; a variable-speed motor configured to drive the horizontal driven take-off roll and control thread tension; a thread tension sensor through which the unwinding thread passes; a tension controller device configured to at least one of increment, maintain and decrement a speed of the variable-speed motor in accordance with a feedback signal from the tension sensor; and at least one guide roll configured to output the thread from the tension control apparatus; wherein the pretensioner and guide roll are located before the horizontal driven take-off roll, and the tension sensor is located after the horizontal driven take-off roll, and wherein the speed of the variable-speed motor is varied to maintain thread tension values within a predetermined range of thread tension by the tension controller device.
Another embodiment of the invention is a drive and tension control apparatus for a thread unwinding system, comprising: a pretensioner and guide roll configured to guide the thread through a thread path of the drive and tension control apparatus; at least one eyelet configured to prevent tangles of the thread; a driven take-off roll configured to move the thread through the drive and tension control apparatus; a variable-speed motor configured to drive the driven take-off roll and control thread tension; a tension sensor configured to determine the tension on the thread; a tension controller device configured to at least one of increment, maintain and decrement a speed of the variable-speed motor in accordance with a feedback signal from the tension sensor; and at least one guide roll configured to output the thread from the tension control apparatus, wherein the pretensioner and guide roll is located before the driven take-off roll and the tension sensor is located after the driven take-off roll.
Yet another embodiment of the invention is a method for controlling thread tension in an elastomeric thread unwinding system for unwinding a plurality of threads concurrently, comprising: unwinding each elastomeric thread from a thread packaging with an associated driven take-off roll for said thread, which roll is driven by a variable-speed motor; guiding each elastomeric thread with an individual pretensioner and associated guide roll into a tension and control apparatus; passing each elastomeric thread through an associated tension sensor; determining whether one or more threads are broken; determining whether one or more threads are moving and measuring the tension of each of the moving threads; determining whether any of the moving threads have a tension that is out-of-range relative to predetermined tension values; at least one of incrementing and decrementing the speed of the respective driven take-off roll for a respective moving thread when the tension of said respective moving thread is out-of-range relative to the predetermined tension value for said moving thread, and at least one of the number of increments and decrements is below a first correction threshold; determining whether an average tension for the respective moving thread is out-of-range relative to the predetermined tension value for said moving thread; at least one of incrementing and decrementing the speed of the respective driven take-off roll when the average tension of said respective moving thread is out-of-range and at least one of the number of increments and decrements is below the second correction threshold; and setting an alarm when one or more of the threads are at least one of broken, not moving and out-of-range and above the first or second correction threshold.
In addition, in embodiments of the invention guide rolls may be located before and after the driven take-off roll, the tension sensor may be located after the driven take-off roll, wherein the speed of the variable-speed motor can be maintained or varied to maintain thread tension values within a predetermined range of thread tension by the tension controller device, and wherein a distance between the tension sensor and the horizontal driven takeoff roll may be fixed and minimized to avoid errors in the thread tension variations related to distance.
Further, in embodiments of the invention each drive and tension control apparatus further comprises an idler configured to dampen tension variations in the thread, wherein the idler is located adjacent to the horizontal driven take off roll. In addition, each drive and tension control apparatus further comprises a plate eyelet configured to pass the thread to the drive and tension control apparatus.
Moreover, in embodiments of the invention, each of the plurality of drive and tension control apparatus may be spaced apart vertically on the support frame in order to unwind each of the threads individually from a respective package of the plurality of packages. In addition, The OETO creel system the plurality of drive and tension control apparatus are configured in parallel on the support frame to unwind each of the threads individually from a respective package of the plurality of packages.
Several embodiments of the invention will now be further described in the following more detailed description of the specification when read with reference to the accompanying drawings in which:
The apparatus for unwinding yarns allows for the cost efficient use of an OETO method with rewound yarn and/or as-spun OETO yarn with anti-tack additives. Yarn without anti-tack additives may also be as-spun OETO if tension control equipment is used. In particular, the apparatus continuously unwinds as-spun OETO yarns and delivers a relatively constant yarn tension in a relatively small footprint. This provides for improved efficiency in manufacturing processes.
The two pivoting legs 141, 113 contain a plurality of pivoting yarn holding arms 120 (see
In addition,
A non-limiting example of an active and a standby package 105 is a full 3 kg creel package of a wound fiber or yarn. While not wishing to be limited, an exemplary yarn for OETO unwinding is spandex (segmented polyurethane), such as LYCRA® sold by INVISTA SARL (formerly DuPont). The active and standby packages 105 typically occupy either of two adjacent pivoting yarn holding arm 120 positions on the small footprint frame 100. The pivoting yarn holding arms 120 pivot for easy access to the active and standby packages 105. The pivoting yarn holding arms 120 hold regular yarn tube cores (e.g., as-spun OETO material).
As can be seen in
Referring still to
According to a preferred embodiment, a user may enter a desired tension range that is to be maintained for the thread group directly into tension controller device 119. The tension controller device receives input signals from the tension sensors 115-115′″ representative of the thread tension. Tension controller device 119 uses these input signals to determine whether the tension level of the thread 102-102′″ coming off driven take-off roll 111 can be maintained because it is within the desired tension range, or whether the tension needs to be increased or decreased. Variable-speed motors 127 of the drive and tension control apparatus 110-1A and 110-1B, as shown in
If the tension controller device 119 determines that the thread tension after driven take-off roll 111 is too high, the tension controller device 119 will increase the speed of motor 127. Alternatively, if the tension controller device 119 determines that the thread tension after driven take-off roll 111 is too low, the tension controller device 119 will decrease the speed of motor 127.
As described above, the compact OETO creel system 100′ may be configured to look at a signal from a thread processing manufacturing system as well as a signal from the tension sensor 115 in determining the appropriate speed for motor 127, as shown in
As can be seen in
As shown in
However, in alternative embodiments, the use of guide systems can be minimized or may be avoided by taking threads directly from guide 138 to driven take-off roll 111. As shown in
According to one embodiment, as shown in
In particular,
While diaper manufacture has been described herein, thread groups may be supplied by the OETO creel system to other thread processing manufacturing systems. In operation, the diaper machine or other thread processing manufacturing system is likely to provide a signal to the tension controller 119, as shown in
According to another embodiment, a user may enter a desired tension range that is to be maintained for the thread group directly into the keyboard 123 of the tension controller device 119. The tension controller device 119 receives input signals from the tension sensor 115 representative of the thread tension. Tension controller device 119 uses these input signals to determine whether the tension level of the thread coming off driven take-off roll 111 can be maintained because it is within the desired tension range, or whether the tension needs to be increased or decreased.
If the tension controller device 119 determines that the thread tension after driven take-off roll 111 is too high, the tension controller device 119 will increase the speed of motor 127. Alternatively, if the tension controller device 119 determines that the thread tension after driven take-off roll 111 is too low, the tension controller device 119 will decrease the speed of motor 127.
As described above, the compact OETO creel system 100′ may be configured to look at a signal from a manufacturing system as well as a signal from the tension sensor 115 in determining the appropriate speed for motor 127. In alternative embodiments, the drive and tension control apparatus 110-1A, 110-1B of the compact OETO creel system 100′ may be configured to look only at a signal from tension sensor 115 (i.e., a tension feedback signal) in determining the appropriate speed for motor 127. Further, the compact OETO creel system 100′ may include multiple sensors that sense tension or other parameters from which the system may adjust the appropriate speed of motor 127.
When only a single thread is being driven by driven take-off roll 211, the guide system for a thread feeding system may be simplified as compared to a system using multiple threads wherein thread paths must be kept separate. For example, a guide system having only a static guide, such as a ceramic eye, through which the thread passes after coming off a package, and a first guide roller to direct the thread towards driven take-off roll 211.
In one embodiment of the single thread configuration of
To reduce the likelihood of such slack in the thread before reaching driven take-off roll 211, a pretensioner may be used in the first guide roll 213A. Background art pretensioners rely on friction between the thread and the pretensioner to maintain tension in the thread feeding system and avoid slack in the thread. However, such friction-type pretensioners are not applicable to elastomeric threads where tack is an issue.
Accordingly, pretensioner guide roll 213A uses a pretensioner which otherwise hinders the speed of rotation of the guide roll. In one embodiment of the invention for pretensioner guide roll 213A, a magnet is positioned adjacent to pretensioner guide roll 213A and a material that is coupled to the guide roll. The material to be coupled to the guide roll is, for example, a ferrous metal such as steel. The magnetic force slows the rotational speed of the pretensioner guide roll 213A and thereby maintains the tension and eliminates slack in the thread without relying on friction.
Moreover, as shown in
The tension sensor 215 is positioned after driven take-off roll 211. The guide roll 213B is located after driven take-off roll 211. The thread maintains a second wrap angle (θ2) across tension sensor 215 that provides an accurate and consistent measurement of the thread tension in the range of 0 to 180 degrees of circumference. The thread is pressed against the thread guides before and after the tension sensor to guarantee a consistent second wrap angle (θ2). The second wrap angle (θ2) can be obtained by the proper positioning of guide rolls 213B, driven take-off roll 211, and tension sensor 215. A tension controller device 219 monitors the thread tension measured by tension sensor 215 and at least one of increments, maintains or decrements the speed of the variable-speed motor 227.
As shown in
When only a single thread is being driven by driven take-off roll 411, the guide system for a thread feeding system may be simplified as compared to a system using multiple threads wherein thread paths must be kept separate. For example, a guide system having only a static guide, such as a ceramic eyelet plate 403, through which the thread passes after coming off a package, and a first eyelet 430 and a second eyelet 432 that direct the thread towards driven take-off roll 411.
In one embodiment of the single thread configuration of
To reduce the likelihood of such slack in the thread before reaching driven take-off roll 411, a combination of a guide roll 422 and pretensioner 420 is used. A non-limiting example of such a pretensioner is Model No. JH-703A from Da Kong Enterprise Co., Ltd, Chung Shan Road, Chang Hua City 500, Taiwan. Background art pretensioners rely on friction between the thread and the pretensioner to maintain tension in the thread feeding system and avoid slack in the thread. However, such friction-type pretensioners usually are not applicable to elastomeric threads where tack is an issue.
Pretensioner 420 hinders the speed of rotation of the guide roll 422. As shown in
The drive and tension control apparatus 110-3 in
As compared to the previous embodiments of the OETO creel system with drive and tension control apparatus, the guides have been changed from rollers/pigtails to eyelets (e.g., 430, 432). The use of eyelets reduces the chance of tangles, trapping or breaking due to ballooning of the thread between a package and the first guide. Embodiments of the invention may use individual eyelets and plates. Preferably embodiments of the invention use a single plate 403 with holes/eyelets, as shown in
As discussed above, the friction pretensioner (e.g., 420 in
In particular, as compared to the previous embodiments of the invention and the background art, the driven roll 427 has an idler 421 attached, as shown in
In addition, as shown in
When no broken threads or fibers are detected in step 1603, the method determines whether the threads or fibers are moving in step 1604 of
In step 1612 of
In accordance with whether the out-of-range tension is above or below the predetermined range, the motor speed is decremented or incremented, respectively, in step 1614 of
When no out-of-range tension values are detected for the individual threads or fibers, the method determines an average value for the tension of multiple threads or fibers in step 1615 of
In step 1618 of
The correction threshold is a predetermined value that is entered in the algorithm at initialization and may be updated in real-time. The predetermined value is a maximum number of corrections that are to be allowed by the algorithm before operator intervention is suggested. The values for the predetermined value of the correction threshold may be different in terms of the number of decrements and the number of increments that are determined to exceed the threshold.
When the correction threshold has been exceeded, by either or both the number of increments or decrements, a TENSION UPDATE alarm is set in step 1625 and the algorithm is stopped at step 1627C. When the algorithm is stopped at either of steps 1627A, 1627B or 1627C, as discussed above, the operator can read the alarm status of the equipment and take the appropriate steps to intervene and correct the process.
When the average value of the yarn, thread or fiber tension is not out-of-range, the method maintains the motor speed, as indicated in step 1621 and returns to step 1603 to repeat the above discussed trim tension monitoring algorithm. The above-discussed algorithm may be applied to one or more yarn, thread or fiber being delivered by an OETO creel or drive and tension control apparatus.
The following examples include experiments with Lycra® XA® spandex fibers having no topically applied finish and provide information on the performance of embodiments of the invention.
The test equipment used in obtaining the data for this and the following examples, could be configured in various ways, such as optionally including or excluding certain design elements and changing the sequence of certain elements. The equipment configuration employed for examples 1 to 5 is shown in
The test equipment geometry and other experimental test conditions are summarized below:
The distances between the static guide and the first driven roll, between the first driven roll and the tension sensor and between the first driven roll and the take-up roll were 0.22, 1.94 and 2.1-3.4 meters, respectively. In this example, the first driven roll, having a diameter of 8.89 cm. was not grooved. The threadline was maintained in the horizontal plane (relative to ground), and its directional change within that horizontal plane as it passed through the static guide, was maintained constant at 0°. The distance between the package and first guide was varied. The threadline was wrapped 360° around the first driven roll. The threadline draft was controlled at 2.15×. by maintaining the surface speeds of the first roll at 93.4 meter/min, and the surface speed of the take-up rolls at 294.3 meters/min.
Tension data (expressed in grams) were collected with a Model PDM-8 data logger, and a Model TE-200-C-CE-DC sensor (Electromatic Equipment Co.). All tension measurements were averaged over five-minute run time using a data sampling frequency of approximately 82 samples/sec.
“Mean range tension” was determined as follows: within every 1.25-second interval of the tension measurement, the minimum and maximum tension levels were recorded (yielding 103 data points). Mean range tension was calculated by averaging the differences (between the minimum and maximum values) over the 5-min run.
The fiber evaluated in this test was as-spun Lycra® XA® spandex (a registered trademark of INVISTA SARL, formerly E.I. du Pont de Nemours and Company) having a linear density of 620 dtex (decigram per kilometer).
TABLE 1 shows the thread line tension variations, as measured at the sensor, as the distance, d, between the package and the static guide was varied over a distance between about 0.25 and 0.81 meter.
TABLE 1 demonstrates that thread line tension (expressed either as the mean range or the maximum tension) decreases as the distance between the package and the static guide is increased. Minimum tensions, not shown in the table ranged from about 0.6 to 1.4 grams. Unexpectedly, it has been discovered that there is a minimum distance of about 0.41 meter below which the absolute level of tension and the tension variability (as observed by plotting, for example, maximum tension versus distance) rises to an unacceptably high level identifiable by the occurrence of threadline breakages which are usually preceded by a relatively abrupt increase in mean range tension.
The same test equipment as described in EXAMPLE 1, but configured to more closely correspond to the preferred embodiment of the OETO unwinder design shown in
The distances between the static guide and the first driven roll, between the first driven roll and the tension sensor, and between the first driven roll and the take-up rolls were 0.43, 0.51 and 2.43 meters, respectively. The first driven roll was a single roll having a single groove with a depth of 0.38 mm. The threadline was again maintained in the horizontal plane. The distance between the package and the static guide was held constant at 0.65 meter while the angle, θ, was varied. Threadline draft was maintained at 4× by controlling the first driven roll and the take-up rolls, respectively, at surface speeds of 68.6 and 274.3 meters/min.
In addition to monitoring threadline tension as in EXAMPLE 1, tension spikes were also recorded. “Tension spikes” are the average number of sudden increases in tension greater than 25 grams above baseline tension in a 5-min period.
Various as-spun Lycra® XA® spandex fibers, exhibiting different levels of tack, were evaluated. Tack levels were characterized by measuring the OETO tension (in grams) by the following method: The fiber package and a ceramic pig tail guide were mounted 0.61 meter apart, such that the axes of each were directly in line. The fiber is pulled off the package over end at a threadline speed of 50 meters/min, through the guide, and through a tension sensor.
TABLE 2 shows the threadline tension variations as the angle θ increased; where θ is defined as the acute angle made by the intersection of the imaginary lines corresponding, respectively, to the rotational axis of the package and the central axis of the static guide orifice that is perpendicular to the plane of the orifice.
Examination of the data in TABLE 2 reveals an unexpected relationship between threadline tension and the angle between the centerlines of the package and the static guide. As the angle increases so does thread line tension, and tension spikes occur more frequently. At sufficiently large angles, thread line breakage can occur. The sensitivity of thread line tension to the angle traversed by the thread line as it passes through the guide is dependent upon the properties of the fiber. The data of Table 2 indicates that fibers characterized by higher tack exhibit higher sensitivity of thread line tension with respect to this angle. For some fibers that exhibit an exceptionally high level of tack, the angle above which thread line breakage cannot be avoided is less than about 10°.
This series of runs, using the test equipment described previously and configured as in EXAMPLE 2, evaluated the effect of angle on threadline tension for fibers of different tack levels. The distance, d, between the package and the static guide was maintained constant at 0.65 meter. Threadline draft was maintained at 4× by controlling the first driven roll and the take-up rolls, respectively, at surface speeds of 68.6 and 274.3 meters/min. All other experimental conditions were as described for EXAMPLE 2. The data are summarized in TABLE 3.
The high tack fibers tested in this series of runs are the same as two of the fibers tested in EXAMPLE 2. Comparison of the data for these same fibers in TABLE 2 and TABLE 3, shows that thread line tension increases with increasing angle, and thread line breakage may occur at excessively high angles. (In contrast, fibers containing finish can be run at angles of up to and including 90° with no increase in thread line tension, no occurrence of tension spikes and no thread line breaks. When Lycra® XA® T-162C fiber, 924 dtex den, merge 16795 (lot 1019), finish, having a tack of 1.406, was run at angles of 0-90°, there was no threadline tension increase and no tension spikes.)
These data demonstrate that limiting the angle the thread line traverses as it passes through the first static guide provides uninterrupted manufacturing processing even for high tack fiber threadlines.
This series of runs using the test equipment described previously and configured as in EXAMPLE 2, evaluated the effect of the distance, d, between the package and the static guide on threadline tension for fibers of different tack levels. The angle, θ, was maintained constant at 22°. The threadline draft was controlled at 4× and the take-up speed at 274.3 meters/min.
The test results for these fibers in TABLE 4 show the minimum distance between the package and the fixed guide below which the threadline tension and mean range tension increase unacceptably. The value of this minimum depends upon the tack level of the fiber being tested. In contrast, there is essentially no effect of package-to-static guide distance on the lower tack Lycra® spandex. These results reinforce the difficulty in maintaining smoothly running process conditions with high tack fibers. The OETO creel system allows successful control of processes utilizing such fibers.
A test of the operation of embodiments of the invention was conducted under commercial production conditions using fibers that were characterized by different levels of tack. TABLE 5 summarizes these test results. Data were obtained as in previous examples, except that each of the tension measurements reported is the average of a minimum of 4 separate measurements, each measurement consisting of one tube running for a 10-min period. Similarly, each number of tension spikes, as reported in TABLE 5, is the average number of spikes greater than 25 grams above baseline tension in a 10-min period. Measurements were made on packages that were nearly full (surface) or nearly empty (core). Core measurements are those with about 1.6-cm thickness of thread or fiber remaining on the tube. Of the 5 as-spun fibers run, 4 ran with no operational problems. One fiber sample, Merge 1Y331, did result in an unacceptable occurrence of tension spikes. That fiber demonstrated an unusually high level of tack, even for as-spun fiber, as evidenced by the fact that the mean range tension was over 60% higher than that of the fiber exhibiting the next highest level of tack.
The foregoing description illustrates and describes the present invention. Additionally, the disclosure shows and describes only the preferred embodiments of the invention, but, as mentioned above, it is to be understood that the invention is capable of use in various other combinations, modifications, and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein, commensurate with the above teachings and/or the skill or knowledge of the relevant art. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with the various modifications required by the particular applications or uses of the invention. Accordingly, the description is not intended to limit the invention to the form or application disclosed herein. Also, it is intended that the appended claims be construed to include alternative embodiments.
| Number | Date | Country | |
|---|---|---|---|
| 60925423 | Apr 2007 | US |
