WO2001023257A2

WO2001023257A2 - Method and apparatus for winding yarn on a bobbin

Info

Publication number: WO2001023257A2
Application number: PCT/US2000/026945
Authority: WO
Inventors: Larry J. Huey
Original assignee: Advanced Glassfiber Yarns, Llc
Priority date: 1999-09-30
Filing date: 2000-09-29
Publication date: 2001-04-05
Also published as: WO2001023257A3; AU7841300A

Abstract

Method and apparatus for forming a twisted bobbin (39) from forming packages (20) normally used to make zero twist yarn. One embodiment includes substituting a zero twist yarn forming packages (20) for conventional forming packages (1) on a conventional twist frame. A twisted yarn package (39) made from a zero twist yarn forming input (20) or any forming package whose diameter does not change during a building cycle does not have the tendency for short-term yardage, twist or drying variations and the resulting problems. In a second embodiment (Figure 3), the making of the strand path (33) of the top and bottom creels (31, 34) equivalent reduced air jet loom flight time CV from about 3 % to about 2 %. In a third embodiment (Figures 4-5), it was found that a more uniform bobbin (119, 219) was obtained by adding a metering device, Godet roll (111, 211) to the supply strand (112) from a conventionally driven rotating creel (104) or a stationary creel (204). Alternatively, a contactive drying device (a heated godet roll) may be used to dry the yarn (112) between the creel and spindle. In yet another aspect, there is provided a zero-twist yarn-forming package with an inside draw from a stationary creel.

Description

METHOD AND APPARATUS FORWINDING YARN ON A BOBBIN

BACKGROUND OF THE INVENTION (1) Field of the Invention This invention relates to methods and apparatus for forming a yarn package. More particularly, this invention relates to forming a bobbin having improved yarn uniformity and an improved, metered length.

(2) The Prior Art

A twist frame is used for winding and twisting filamentary material onto a plurality of rotating bobbins from a package of yarn. Standard glass fiber yarn forming packages are generally made by using a spiral wire device, usually called a package builder, or just builder, to distribute the yarn strand laterally across the collet. A pair of helical wires rapidly rotates, throwing the strand back and forth. Additionally, the spiral wire apparatus slowly oscillates back and forth along the collet. The combination of these movements creates a stable forming package that does not collapse during subsequent handling and one that unwinds for further processing. The lay of the strands during winding is not precisely controlled - prevention of parallel strand alignment that would glue strands together and inhibit proper unwinding is due mostly to the pseudo-random placement of the strands by the spiral wire. Process settings are important, however, and a bad process setup can make unwinding very difficult in spite of the pseudo-random strand placement.

The package formed by a spiral wire winder is humped, i.e., it has a large diameter in the middle tapering to a feather edge on the ends. Because the attenuation of the fibers is controlled by the collet rotational speed and the local package diameter, the short term variation in yardage (inverse tex, or inverse denier, or inverse linear density) is appreciable, especially as the package nears its maximum size. In a few feet of strand length, the diameter of the package on which the strand is running can go from 11" to 13" or more.

Yarn packages are typically unwound from the outside of a rotating creel on a twist frame. Because the bottom creels are closer to the bobbins than that top creels the differences in the length of the yarn paths is significant. Also, strand payoff from the humped package has a short-term variability that gives a variation in the twist level of the final twisted strand. Strands in the feathered edge dry faster (due to reduced package thickness in that area) than do strands from the humped center. This is thought to cause short-term strand integrity variations. Twist level and strand integrity variations translate into pick flight time and air pressure variations on air jet weaving looms that can lead to flaws in the woven fabrics.

In response to demands for increased productivity and efficiency, users of wound fiber strand packages, such as weavers and knitters, continually challenge producers to provide high quality wound packages having uniform usable product. However, present yarn packages continue to suffer from uneven stand tension or differing tension between packages, which causes problems when weaving. Also, bobbins sometimes contain different lengths of yarn which is of concern to customers.

SUMMARY OF THE INVENTION It has been found that forming packages normally used to make a zero twist yarn may be used to form a twisted bobbin. In one embodiment of this invention, zero twist yarn forming packages are substituted for conventional forming packages on a conventional twist frame. A twisted yarn package made from zero twist yarn forming input does not have the tendency for short-term yardage, twist or drying variations and the resulting problems. Any forming package whose diameter does not change substantially during a builder cycle will provide these benefits. Additionally, lack of a feathered edge provides the possibility for new twisting concepts, i.e., withdrawal of the strand from the inside of a stationary package with strand speed (and metered strand length accuracy) much more precisely controlled.

In a second embodiment, it was found that lengthening the strand path on the bottom creel positions in a twist frame reduced air jet loom flight time CV from about 3% to about 2% making the bottom creel equivalent to the top creel. In this embodiment both conventional forming packages and zero-twist packages may be used. Further, the bottom creel flight time autocorrelation function showed that flight time variability went from highly correlated (non-random) to mostly uncorrelated (more random), again making the bottom creel more like the top creel. No one has previously recognized the difference in the yam between the top and bottom creels of a twist frame. The strand path for the bottom creel is much shorter. By lengthening the bottom creel strand path, the quality of the bottom creel yam is made better and about the same as the top creel yam.

In a third embodiment of this invention it was found that a more uniform bobbin was obtained by adding a metering device to the supply strand from a conventionally driven creel. In this embodiment the metering device is a godet roll, positioned between the creel package and the twisting process. Work beyond the basic substitution concept includes using a heated, multi-wrapped godet roll for metering and/or drying the yam. The creel can be rotating or stationary. Alternatively, a contactive drying device (a heated godet roll, for instance) to dry the yam between the creel and spindle may be used. In yet another aspect of this invention, there is provided a zero-twist yam-forming package with an inside draw from a stationary creel.

Therefore it is an object of the present invention to provide a method and an apparatus to provide a twisted yam bobbin from a zero-twist yam forming package or other similar forming package with approximately constant package diameter per builder cycle.

Another object of the present invention is to provide a method and an apparatus using a forming package that does not have the tendency for short-term yardage, twist or drying variations.

A further object of the present invention it to provide a method and apparatus for altering the path length of the bottom twist frame creel to improve yarn uniformity between bobbins wound from bottom creels and top creels on a twisted yam bobbin.

Yet another object of the present invention is to provide improved metered length accuracy and improved twist uniformity in forming a twisted yam bobbin. BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing objects, features, advantages and preferred embodiments of the yam package and the method of producing the yam package will be better understood from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is an isometric view of a prior art cylindrical forming package;

Figure 2 is an isometric view of a zero yam twist forming package used in the present invention;

Figure 3 is a general schematic of an embodiment of the invention illustrating the altered path length modification for the bottom creels;

Figure 4 shows an embodiment of another aspect of this invention illustrating the metered twisting concept for a rotating creel; and

Figure 5 shows an embodiment of another aspect of this invention illustrating the metered twisting concept for a fixed creel.

DETAILED DESCRIPTION OF THE INVENTION The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In Figure 1 there is shown an isometric view of a prior art cylindrical forming package 1 have glass fiber would on a tube. In forming packages of this type glass fibers 3 are wound on a tube 2. The cross-section shape of the forming package 1 is approximately trapezoidal, as shown.

In contrast to the typical yarn packages described in Figure 1 , zero twist forming packages are approximately cylindrically shaped, as shown most clearly in Figure 2. The ZTY builder, a strand guide oscillating in a barrel cam, creates a package 20, of glass fibers 23 wound on tube 22 whose diameter is almost constant from edge to center. This gives a package whose short-term variation in linear density is much lower than conventional packages. More generally, any forming package whose diameter does not change substantially during a builder cycle will provide these benefits. Cylindrical zero twist forming packages are just one example of packages with constant package diameter per builder cycle. Those skilled in the art will appreciate that other embodiments of the forming package can accomplish the same objectives. Additionally, the package is precision wound. This means that the strand is very precisely placed on the package in a given pattern, strand overlap can be made practically nonexistent, and unwinding of the strand can proceed with almost no chance of interruption. It also means that the second motion needed to stabilize a spiral wire package is not needed. A twisted yarn bobbin wound from a zero twist winder input does not have the tendency for short term twist or drying variations and the resulting problems. Further, lack of a feathered edge provides for new twisting concepts such as withdrawal of the strand from the inside of a stationary package with strand speed (and metered strand length accuracy) much more precisely controlled.

Referring now to Figure 3, there is shown a twist frame 30 using the zero twist forming packages 31, 34 described in Figure 2 to form bobbin 39. In addition to the zero twist forming packages, Figure 3 also discloses a modification to a conventional strand path from the forming packages 20, shown in Figure 3 as bottom creels 34, on a typical twist frame. A yam strand is removed from the forming package passed along a predetermined path to the bobbin. In one embodiment the yam 32 passes from bottom creels 34 upwards through guides 35, then turning it back downward through the guide bars 36 increases the strand path 33 length. The guides 35 for the bottom creels 34 may be placed anywhere on the twist frame 30 so long as the strand paths 33 are approximately equal in length to the upper strand paths. The strand paths 33 continue through the pigtail guides 37, the travelers 38 and onto the take-up bobbins 39. This modification to the twist frame may be used with a zero-twisting process (with precision-wound, square edged forming packages), or with conventional yam forming package inputs. The forming packages 20 located toward the upper portion of the twist frame 30, shown in Figure 3 as top creels 31, continue in the conventional manner with the yarn 32 being unwound from the top creels 31 and passing through the guide bars 36. The strand paths 33 continue through the pigtail guides 37, travelers 38, and onto the take-up bobbins 39. The strand is moved along the predetermined path at such speed as to provide a precisely wound bobbin. A motor (not shown) is provided for rotating the bobbin. It should be understood that the method of this second embodiment may use either conventional or zero-twist packages.

It was found that variability in the yam from the bottom creel could be significantly improved by this modification. On heavy yams, loom flight time CV (a measure of strand uniformity) was reduced from about 3% to about 2%. This improved uniformity was about the same as that measured on yam from the top creel. Additionally, when a twisted yam bobbin was wound from zero-twist yam the variability was made more random by the modification. Previously, the flight time autocorrelation function showed a great deal of non-random structure even at large lags. After the modification, the autocorrelation function showed much less stmcture and more random behavior. After modification, the autocorrelation functions for the top and bottom creels were about the same.

Although the causes for the improvement are not precisely known, it is known that the increased free strand length gives more time for the strand to dry exposed to the air. Further, strand transverse vibration is larger with the longer free length (and substantially more than with the original stand path) - this may enhance both drying of the strand and reduction of strand integrity by the vibratory motion. Finally, the extra contact surface required to turn the strand may contribute to strand integrity reduction by mechanically working the strand. The effect is more pronounced in heavy yams where strand drying is more difficult than it is in light yams.

In another aspect of this invention, that shown in Figure 4, a conventional driven creel with a metering device to supply strand to the twisting operation is provided. In a conventional, outside-draw creel, the rotational rate of the creel package is controlled (either constant, or matched to spindle speed). However, strand speed (and strand length) is not constant but is a function of the rotational rate and the local package diameter. For a large conventional yam package, diameter variations along the package length are not trivial. The problem is less severe for a cylindrical forming package of zero-twist yam. However, both package types are subject to variability in length per creel revolution caused by bushing throughput or other variabilities in the forming process when the forming package was made. Thus the prescribed number of creel revolutions for a given metered length is only a rough average - some packages may vary from this average by a substantial amount. It has been found that this limitation is overcome by providing a feeding device between the creel package 104 and the twisting process. The metering device 111, shown in Figure 4, is a godet roll of a type well known in the polymer fiber industry. The yam strand 112 passes through inlet guide 114 to the godet roll. The yam strand 112 is wrapped around the godet roll enough times (about 4- 8) to prevent slippage. The godet roll 111 may be heated and if so the number of wrapped turns should be such as to give sufficient area for contactive heat transfer from the heated roll surface. A separator roll 112, whose axis is canted with respect to the godet roll axis, maintains separation between successive wraps. The strand path 113 continues through guide bar 116, pigtail guide 117, traveler 118 and onto the take-up bobbin 119.

As shown in Figure 5, there is provided another embodiment, having a fixed creel 204 mounted to center stand turning guide 205 having an inside draw. Yam strand 212 is passed from creel 204 and wrapped around the godet roll enough times (about 4-8) to prevent slippage. Otherwise the apparatus is similar to that of Figure 4. After leaving godet roll 211 the strand path 213 continues through guide bar 216, pigtail guide 217, traveler 218 and onto the take-up bobbin 219. This embodiment requires a self-supporting forming package whose tube could be removed. Potential advantages with this embodiment include easier end finding and migration removal which would significantly reduce labor costs, simpler stationary creel and easier creel loading. It was found that uniform twisted yam packages could be wound from zero-twist yam using this apparatus.

It should be recognized that the above-described embodiments are not the only possible feeding devices. The primary requirement is that the yam strand be maintained in non-slipping contact with a surface whose surface speed is known. A controlled speed is also desirable for twist control, but as long as the speed history is known, accurate length delivery is possible. This can be provided by many possible devices, including S-wrapped draw rolls, pinch rolls, pinched conveyor belts.

Either conventional or squared-edged packages can be used, and blowers, cold air blowers, hot air blowers, or the heated godet roll can be used to dry the yarn strand. Other heating devices such as wire contactive "hot fingers", infrared or dielectric drying, and the like may also be used. Combinations of these drying mechanisms can be used to alter strand properties like stiffness and integrity. The heat provided by the godet roll can be ramped to compensate for the increasing amount of moisture in the package as the exterior layers are removed. It is probably necessary to provide a small amount of drag (with an eddy-current device, for example) on the creel package to prevent slack strand (strand removal speed would be constant while strand length per creel revolution would vary).

In addition, twist level control can be substantially improved with a metering device. The twist imparted to the yam is determined by the ratio of spindle revolutions per length of strand fed from the creel. Accurate input length control should improve both short-term and long-term variation.

Although the apparatus and methods are described as used in a twist frame environment, it will be understood that the apparatus and methods are not limited thereto. For example, the means for supplying an essentially continuous source of strand to the take-up reel may encompass means to feed a plurality of strands from many forming packages held on a creel and gathered into a single, much larger strand, usually referred to as rovings. This roving yarn is then subsequently wound onto a tube carried on an appropriately powered rotating mandrel. Similarly, a continuous source of strand may be supplied from an operating fiberglass bushing wherein individual filaments drawn from the bushing are gathered into strands that are wound onto a forming tube carried by an appropriately powered rotating winder.

Among the advantages of using the methods and apparatus described herein include: lower short-term yardage; better average yardage; precise waywind control eliminating parallel strand lays and trapped ends often encountered with spiral wire processes; and better metered length control - precise control of package dimensions, coupled with better speed control.

Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A method for forming a bobbin of twisted glass fiber yams comprising: providing a forming package whose diameter does not change during a building cycle; removing a glass fiber yam strand from said forming package; providing a predetermined path for said glass fiber yam strand from said forming package; providing constant speed of said glass fiber yam to a take-up bobbin; and directing said glass fiber yarn strand onto a take-up bobbin.

2. The method according to Claim 1 wherein said forming package is a zero-twist forming package.

3. The method according to Claim 1 further comprising directing said glass fiber yarn strand along said predetermined path through a metering device.

4. The method according to Claim 3 wherein said meter device is a godet roll.

5. The method according to Claim 4 wherein said godet roll is heated.

6. The method according to Claim 4 wherein said glass fiber strand is wrapped about said godet roll a sufficient number of turns to prevent slippage.

7. The method according to Claim 4 wherein said providing step includes a roll whose axis is canted with respect to the godet roll axis to thereby maintain separation between successive wraps of the glass fiber yam strand as it passes around the godet roll.

8. A twist frame for forming a bobbin of twisted glass fiber yams comprising: a forming package of wound glass fiber yam whose diameter does not change during a building cycle removably placed on said twist frame; a predetermined path for said glass fiber yam strand from said forming package; means for providing a constant speed of said glass fiber yam along said predetermined path to a take-up bobbin; and means for winding said glass fiber yam onto said take-up bobbin.

9 The apparatus according to Claim 8 wherein said yam forming package is a zero-twist forming package.

10. The apparatus according to Claim 8 further comprising a metering device through which said glass fiber yam strand is passed.

11. The apparatus according to Claim 10 wherein said meter device is a godet roll.

12. The apparatus according to Claim 11 wherein said godet roll is heated.

13. The apparatus according to Claim 11 wherein said glass fiber yam is wrapped about said godet roll a sufficient number of turns to prevent slippage.

14. The method according to Claim 11 wherein said providing step includes a roll whose axis is canted with respect to the godet roll axis to thereby maintain separation between successive wraps of the glass fiber yam strand as it passes around the godet roll.

15. A method for winding yam about a bobbin comprising: providing a twist frame having a plurality of top creels and bottom creels, said creels being a forming package; removing a glass fiber yam strand from said forming package; providing a predetermined path for said glass fiber yam strand from said forming package; providing constant speed of said glass fiber yam to a take-up bobbin; and winding said yam about a bobbin supported upon a rotatable collector of a winder to form a yam package.

16. The method according to Claim 15 wherein said forming package is a conventional forming package.

17. The method according to Claim 15 wherein said forming package is a zero-twist forming package.

18. The method according to Claim 15 further comprising adjusting the length of said path of said bottom creels to approximately the length of the path of said top creels.

19. The method according to Claim 15 wherein the length of said bottom creel yam paths is adjusted by passing said yam through guides positioned to extend the length of said bottom creel yam path.

20. The method according to Claim 15 wherein said twist frame includes a spindle having a bobbin releasably mounted thereon.

21. The method according to Claim 20 wherein said spindle includes a spindle drive for rotating the spindle.

22. The method according to Claim 15 further comprising, passing said yarn along said predetermined path through a metering device.

23. The method according to Claim 15 wherein said meter device is a godet roll.

24. The method according to Claim 15 wherein said godet roll is heated.

25. The method according to Claim 15 wherein said glass fiber strand is wrapped about said godet roll a sufficient number of turns to prevent slippage.

26. The method according to Claim 15 wherein said providing step includes a roll whose axis is canted with respect to the godet roll axis to thereby maintain separation between successive wraps of the glass fiber yam strand as it passes around the godet roll.

27. The method according to Claim 15 wherein said yam is drawn from the inside of the forming package.