US20060201129A1

US20060201129A1 - Continuous constant tension air covering

Info

Publication number: US20060201129A1
Application number: US11/076,441
Authority: US
Inventors: Keith Bumgardner
Original assignee: Individual
Current assignee: Unifi Inc
Priority date: 2005-03-09
Filing date: 2005-03-09
Publication date: 2006-09-14
Also published as: CO5710202A1; BRPI0502574A

Abstract

An air covered yarn is formed by feeding multiple polymeric yarns along a predetermined path to an air jet. Before reaching the air jet, the polymeric yarn ends are textured to form covering yarns. An elastomeric core is also fed along a predetermined path to the air jet. The covering yarn and elastomeric core are then pneumatically entangled to form a composite yarn.

Description

FIELD OF THE INVENTION

The present invention relates generally to the field of textiles, and, more particularly, to an improved method and an apparatus for forming air covered yarns.

BACKGROUND OF THE INVENTION

Air covered yarns, which comprise a combination of elastic and inelastic materials, are incorporated widely in the apparel industry in fabrics that require performance stretch and recovery. The process for forming these yarns typically requires two steps. First, two or more continuous filaments of nylon, polyester, or other suitable inelastic polymeric filaments are fed from creel racks through a texturing machine, such as a false-twist texturing machine. The filaments are typically drawn through heating zones where they are stretched, and then cooled, before being routed through a friction unit. The friction unit imparts a crimp, or twist, to the filaments. The cooled, textured filaments are then plied and wound on a take-up roll, or package. The take-up packages are doffed or removed and taken to a separate location in the plant, or to a remote facility, for further processing.
The textured/false twisted polymeric filaments are then combined with a continuous filament of elastic, such as spandex, and fed through an air jet where they are entangled. A conventional air covering machine is used. The entangled composite inelastic/elastic yarn is then wound on a take-up package and prepared for shipment to a customer.
There are difficulties with the existing processes. First, the air covered yarn must normally be produced in at least two steps and, most likely, in two separate plant locations. Second, on conventional air covering machines, the elastic spandex filaments or yarn are fed from a single package for air covering with the inelastic filament yarns. This means that the air covering machine must be stopped and a new creel installed each time the spandex package is depleted. As will be appreciated, this results in frequent and undesirable production stops. Additionally, because spandex is elastic, the tension of the spandex feed inherently varies from the beginning of the spandex package to the end of the spandex package. This can result in a final air covered yarn with an undesirable variable tension from one end of the yarn take-up package to the other. Further, when formed as a two-step process, several months can elapse between the time that the textured nylon packages are produced and the time that they are used in the air covering process. Since textured yarns lose some of their textured qualities (crimp, twist, etc.) over time, an inconsistent quality results in the final yarn, as the age of the textured product in use varies.
For various reasons, textile machine manufacturers have attempted to combine the two steps into single machines, but these combination machines have failed to address the undesirable production stops for changing the depleted spandex packages, or the variability in the tension of the spandex feed.
Despite the ability of those of ordinary skill in the art to identify various ways to lengthen production runs on air covering machines and to more efficiently schedule the manufacture of the false twisted yarn component for air covered yarns, there remains a need for a method to optimize the manufacture and quality of air covered yarns.

SUMMARY OF THE INVENTION

A method for forming an air covered yarn comprises feeding polymeric inelastic yarns along a predetermined path, texturing the polymeric yarns to form a covering yarn, feeding an untextured elastomeric yarn along a predetermined path at a substantially constant tension, wherein the constant tension is maintained by an electronic tension controller, feeding the covering yarn and the elastomeric yarn through the air jet, and pneumatically entangling the elastomeric core and the covering yarn to produce an entangled composite yarn.
This invention also includes a method for forming an air covered yarn comprising multiple steps, including feeding polymeric inelastic yarns along a predetermined path, texturing the polymeric yarns to form a covering yarn, feeding an untextured elastomeric yarn along a predetermined path at a predetermined tension, wherein the elastomeric yarn is continuously fed from a plurality of supply packages, feeding the covering yarn and the elastomeric yarn through the air jet; and pneumatically entangling the elastomeric core and the covering yarn to produce an entangled composite yarn. In a preferred embodiment, the supply packages are spliced together to allow for continuous feeding.
These and other features of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments when considered in conjunction with the drawings. It should be understood that both the foregoing brief description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the prior art method for texturing (false twisting) a polymeric yarn.
FIG. 2 is a schematic of the prior art method for forming an air covered yarn.
FIG. 3 is a schematic of the air covering method of the present invention.
FIG. 4 is a front perspective view of the air covering apparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Certain exemplary embodiments of the present invention are described below and illustrated in the attached Figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention, which, of course, is limited only by the claims below. Other embodiments of the invention, and certain modifications and improvements of the described embodiments, will occur to those skilled in the art, and all such alternate embodiments, modifications and improvements are within the scope of the present invention.
One embodiment of the present invention is directed to a method for forming an air covered yarn comprising an elastic component and a polymeric, inelastic component.
As described herein:
“POY” is an acronym for “partially oriented yarns” and is intended to refer to filament yarns in which the draw ratio is less than normal, resulting in only a partial longitudinal orientation of the polymer molecules.
“Drawing” refers to the process of increasing the length per unit weight of the filaments in order to orient the yarn to achieve desired physical properties.
“Texturizing” refers to the process where one or more continuous filaments or yarns are modified to obtain bulk, twist, or additional strength.
“False Twist Texturizing” refers to a continuous method for producing textured yarns that utilizes simultaneous twisting, heating, and untwisting.
“Elastomeric fibers” refers to continuous filaments which have a break elongation in excess of 100 percent independent of any crimp.
“Inelastic fibers” refers to fibers that do not stretch and recover to the same extent as elastomeric fibers.
“Air covering (entanglement),” also known in the art as “intermingling”, refers to the use of one or more air jets to create turbulence to entangle filaments of continuous filament yarns.
The method of the present invention produces an air covered, or entangled, composite yarn that is produced on a single textile machine in a single production process, wherein the tension of a continuously fed elastomeric yarn is maintained constant.
For many years, elastomeric fibers, such as spandex, have been covered or entangled with relatively inelastic fibers to facilitate processing for knitting and weaving of fabrics that require performance stretch and recovery. The inelastic fibers also provide the elastic composite yarns with acceptable surface characteristics, e.g., hand, for various end uses.
A commonly used processes for forming covered, or entangled, elastomeric yarns requires at least two separate production steps. As a first step, the inelastic yarn must be textured. FIG. 1 is illustrative of one type of conventional process and machine for completing the initial texturing of one or more inelastic yarns, such as polyester or nylon. These inelastic yarns initially are formed as continuously spun filaments of synthetic polymeric materials with deniers typically ranging from about 20 to about 300. In their initial spun states, they are commonly know as POY. POY, however, is not preferred in the production of yarns or fabrics since it lacks the finish or handle characteristics that are desired for apparel. Thus, POY must first be textured. FIG. 1 illustrates one such process for texturing POY. The machine, shown schematically, is illustrative of one of the several machines manufactured by Barmag, AG of Germany. In particular, the machine illustrated in FIG. 1 is a false twist texturing machine. On this machine, a frame 110 supports several (3 are shown) creels, or packages, 113. Each creel 113 holds a take-off supply package 115 of untextured nylon POY. The take-off supply packages 115 each provide a single or multi-filament yarn which is fed in parallel with other yarns to form an initially untextured yarn 120.
The multi-filament yarn 120 may pass over several sets of guides or rollers, depending upon the design and actual configuration of the particular false twist texturing machine. In the exemplary machine/process of FIG. 1, the machine comprises feed rollers 117, 118 and an upper guide roller 119. The upper guide roller 119 aligns and directs the multiple yarns comprising yarn 120 downwardly through a heating zone 130. Shown in FIG. 1 as a heating tube, the heating zone 130 may comprise a plate, enclosure, or semi-enclosure. As those skilled in the art will appreciate, the heating zone 130 may take numerous forms, shapes, and lengths, depending upon the material(s) being textured and the temperature limitations on the synthetic materials.
The multi-filament yarns 120 are drawn typically through the heating zone 130 at a prescribed tension, wherein the filaments are stretched. The temperature in the heating zone is between about 130 degrees Fahrenheit and 500 degrees Fahrenheit. The yarns 120 are fed at a tension of between about 5 grams and about 100 grams. Upon exiting the heating zone 130, the multi-filament yarn 120 is drawn through a cooling zone 140 where air is circulated at ambient temperature to cool the yarn 120 to a point where further downstream processing may be completed.
The next step in the texturing process is false twisting. The yarn 120 is fed through a false twist unit 150, as are known in the art. The false twist unit 150 typically comprises at least one spindle of offset discs moving in identical directions in several axes. One suitable false twist unit is a Type 8 unit, available from Barmag AG of Germany. This produces a yarn 120 having a helical, or spring-like, structure, also known as crimping. As the yarn 120 exits the false twist unit, the amount of crimp in the yarn 120 is maximized. The textured yarn 120 is then wound to form a textured nylon package 165 that is mounted on a take-up collection roller 170. The textured nylon package 165 is subsequently removed and stored until needed. As will be appreciated, winding the yarn 120 on the package 165, handling of the package 165, and subsequent storage of the package 165 result in some loss/reduction of crimp in the yarn 120.
Turning now to FIG. 2, the second step of a traditional manufacturing process for an air-covered yarn can include an air-entanglement machine, shown generally as 200. The machine 200 shown in FIG. 2 is an illustrative representation of an ICBT JD800 air covering machine, available from Rieter ICBT of Lyon, France. A textured nylon package 165 is mounted on a creel 210 to feed the textured nylon yarn 120 to the air jet covering process as the covering, or entangling, yarn. A supply package of elastomeric yarn 225 is mounted on a creel 220 to supply continuous filaments 228 of the elastomeric yarn. The spandex filaments may range widely in size, between 10 and about 2,240 denier. In the air covering machine 200 shown in FIG. 2, the tension of the elastomeric (spandex) yarn must be controlled; however, on machines that are currently in commercial operation, the tension is mechanically controlled by a system of one or more rollers 223 that are adjusted by formulae to a predetermined speed ratio, as is known in the art as “drafting” the elastomer. Unfortunately, however, and as will be appreciated in the art, as the supply package 225 of elastomeric yarn becomes smaller, the tension in the yarn 228 will vary, when controlled solely by a mechanical ratio means. This, of course, results in a non-uniform elasticity in the composite yarn from the beginning to the end of the production run.
Yarns 120 and 228 are subsequently, and simultaneously, fed through a series of rollers 230 and 240 and into the air jet entangler 250. In one embodiment, the air jet entangler is Model No. E-16V, available from International Machinery Sales of Winston-Salem, N.C. The nylon 120 and spandex 228 are entangled (at ambient temperature) to form a composite covered yarn 280. The composite covered yarn 280 is subsequently wound by means of take-up rollers 260 onto take-up packages 270, held by stationary creels 275. The final composite covered yarn 280 is then ready for storage and/or shipment to a customer for incorporation into fabric and items of apparel.
Turning now to the views of FIGS. 3 and 4, the method and apparatus according to the present invention are illustrated. While the prior art processes described above have described the production of composite yarns on at least two different machines and at two different plant locations, the method of the present invention is completed in a one step, consolidated, process wherein the tension of a continuously fed spandex feed is maintained constant.
As illustrated in FIGS. 3 and 4, a consolidated texturing and air covering machine 300 is constructed. A novel spandex creel rack assembly 310 is combined with a modified polymeric yarn texturing machine. In the particular embodiment shown and described herein, the texturing machine so modified is one of several machines manufactured by Barmag AG of Reimscheid, Germany. The creel rack assembly 310 is installed adjacent to the frame of the texturing machine so that the spandex fiber can be more easily fed to an electronic tension controller 320, described below, that is mounted on the frame. The creel rack assembly 310 includes a frame 312 to which multiple creels 315 are affixed for holding multiple supply packages 225 of an elastomeric (spandex) yarn. As shown in FIG. 3, in particular, the creels 315 are positioned so that the supply packages 225 may be tied together. Additional creels 319 may be provided as shown in FIG. 3 for holding a supply of fresh supply packages 226; however, the spandex is fed only from supply packages on creels located at the level of creel 315.
The creels 315 of the apparatus shown in FIGS. 3 and 4 are positioned approximately level with one another, and equidistant from the electronic tension controller 320, so that the supply packages 225 of the spandex yarns/filaments may be spliced together for continuous, un-interrupted air covering operations. This permits the machine operators to more easily change out exhausted supply packages with new supply packages. Further, since the supply packages 225 are equidistant from the tensioner 320, there is no significant change in tension from one package 225 to another package 225 during changeover of the packages 225.
As shown in FIGS. 3 and 4, the supply packages 225 may be tied together at points 317 so that when one package 225 is exhausted, the opposed supply package will then be drawn. As will be appreciated, during the switchover from one package to another, the tension in the feed will temporarily vary slightly, and this variance is overcome by electronic tension control. The spandex supply packages 225 are configured/spooled such that each supply package 225 has a lead 225 a and a tail 225 b. That is, the tail 225 b of a first supply package 225 is manually tied to the lead 225 a of a second supply package. In addition, the creels 315 and the spandex supply packages 225 are angled inwardly toward one another so that the elastomeric yarns may be continuously fed “over-end” with respect to each supply package 225. “Over-end” feeding means that the yarns are fed from the supply package 225 at an angle to the surface of the supply package, instead of being unrolled directly from the package. Whereas the prior art method required that the production process be halted for the change-outs of exhausted supply packages, the present invention permits packages to be continuously replaced and tied together so that the production process does not have to be interrupted. For convenience, the leads 226 a and tails 226 b are illustrated on the spare supply packages 226.
A modified apparatus permits spandex rolls to be “spliced” together so that production does not have to be halted for the changing of the spandex packages. With multiple packages of spandex positioned on the same level and tied together, a constant supply of elastomer is assured in the process. These improvements contribute to a more cost effective, consistent, and higher quality final yarn product. A feature of the present invention is that the resultant air covered yarn is not limited by the size of a single supply packages of elastomeric core material.
Having been fed from the supply packages 225, the elastomeric yarn 228 is next fed through an electronic tension controller 320. Electronic tension controllers are known in the art, but heretofore have not been used for air covered yarn production. One tension controller 320 that has been determined to be suitably used in the textile machine 300 of the present invention is Model No. MF, available from BTSR of Vareso, Italy. The electronic tension controller 320 also comprises tension sensors 322 which provide continuous electronic feedback to the tension controller 320 to maintain a constant tension in the elastomeric yarn 228, regardless of the amount of yarn remaining on the supply package 225.
This electronic tension controller and feeder system 320 use a programmable feeder unit to deliver the spandex at a consistent tension through out the spandex package and from one spandex supply package to another. The sensors 322 continuously monitor the programmed tension and, in conjunction with programmable controller 320, may also used to monitor the length and consumption of any given yarn, including spandex. Accordingly, the electronic tension controller 320 and sensors 322 provide a continuous quality control function of the programmed yarn process parameters, which in the present invention can be tension. Where a tolerance in the tension value is permitted, the programmable controller ensures that the tension in the yarn feed remains within the prescribed tolerance. As will be appreciated, the electronics (circuitry and software, not shown) within the tension controller 320 are compact, which facilitates installation on the combined texturing and air covering machine 300. Depending upon the particular application for the air covered yarn, the tension in the spandex may be maintained between about 0.5 to about 100 grams.
Upon exiting the tension controller 320, the spandex 228 is fed over at least one feed guide 325 so that it can be precisely fed to the air jet entangler 330. Simultaneously with the introduction of the spandex 228 to the air jet 330, the textured nylon yarn 120 is introduced into the air jet 330 in parallel to the spandex 228. As described above, the textured nylon 120 is formed in the same manner as on unmodified texturing machine 100. Both yarns 228 and 120 are fed through the air jet 330 wherein the yarns are entangled to form a composite yarn 380. The composite air covered yarn 380 is further fed over at least one set of rollers 340 before being taken up on a final yarn package (not shown). Unlike the process of the present invention, wherein the textured nylon yarn is fed into the air jet at an elevated temperature, i.e., still cooling, for entanglement with the spandex, the prior art process described above has required two distinct processes involving the composite of yarns textured much earlier. Since the entanglement with the spandex occurs as the textured nylon is exiting the false twist unit, the textured nylon crimp is maximized, and the yarns are tacked together, i.e., bonded, at more points along their entanglement. More specifically, the inventors have observed that the resulting yarn has a smaller diameter, increased uniformity of entanglement, and a higher retention of entanglement during subsequent processing. While the textured nylon eventually will cool to room or ambient temperature, entangling the yarns prior to reaching ambient temperature provides the advantages stated herein. In most textile manufacturing plants, ambient temperature is between about 76 degrees Fahrenheit and 80 degrees Fahrenheit.
Various types of elastomeric yarn can be used, such as spandex, elastane, rubber, polyetheresters, elastoesters, and elasterell P.
Composite yarns produced in accordance with the present invention are described in the examples below:

EXAMPLES



			Final
			Construction/
	Nylon Denier/	Spandex	Composite
Run	Construction	Denier	Denier	Use

1	2/70/34	20	158	Socks
2	1/150/68	20	160	Socks
3	2/70/34	10	154	Socks
4	1/70/34	70	100	Fleece
				Fabric

As those skilled in the art will appreciate from the examples above, the percentage of spandex in the final composite yarn and the denier of the spandex may be varied for forming yarns having different end uses. By splicing the spandex packages together, and thus continuously feeding the spandex to the air jet, the size (diameter) of the take-up package of the composite yarn is not limited by a higher denier spandex or a higher percentage of spandex in the composite yarn.
Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims and their equivalents.

Claims

1. A method for forming an air covered yarn, comprising:

(a) feeding polymeric inelastic yarns along a predetermined path;

(b) texturing the polymeric yarns to form a covering yarn;

(c) feeding an untextured elastomeric yarn along a predetermined path at a substantially constant tension, wherein the constant tension is maintained by an electronic tension controller;

(d) feeding the covering yarn and the elastomeric yarn through the air jet; and

(e) pneumatically entangling the elastomeric core and the covering yarn to produce an entangled composite yarn.

2. The method of claim 1 wherein the elastomeric yarn is selected from the group consisting of spandex, elastane, rubber, polyetheresters, elastoesters, and elasterell P.

3. The method of claim 1 wherein the elastomeric yarn is continuously fed from a plurality of supply packages, the supply packages being spliced together.

4. The method of claim 1 wherein texturing the polymeric yarns comprises:

(a) drawing the polymeric yarns through a heating zone;

(b) cooling the polymeric yarns; and

(c) feeding the polymeric yarns through a false twist unit, wherein the yarns are crimped.

5. The method of claim 4 wherein the covering yarn and the elastomeric yarn are fed through the air jet when the crimp in the textured covering yarn is maximized.

6. The method of claim 4 wherein the polymeric yarn ends are stretched when drawn through the heating zone.

7. A method for forming an air covered yarn, comprising:

(a) feeding polymeric inelastic yarns along a predetermined path;

(b) texturing the polymeric yarns to form a covering yarn;

(c) feeding an untextured elastomeric yarn along a predetermined path at a predetermined tension, wherein the elastomeric yarn is continuously fed from a plurality of supply packages, the supply packages being spliced together;

(d) feeding the covering yarn and the elastomeric yarn through the air jet; and

8. The method of claim 7 wherein a substantially constant tension is maintained in the elastomeric core yarn by an electronic tension controller while the elastomeric core is being fed along the path to the air jet.

9. The method of claim 7 wherein the elastomeric yarn is selected from the group consisting of spandex, elastane, rubber, polyetheresters, elastoesters, and elasterell P.

10. The method of claim 7 wherein texturing the polymeric yarns comprises:

(a) drawing the polymeric yarns through a heating zone;

(b) cooling the polymeric yarns; and

11. The method of claim 10 wherein the covering yarn and the elastomeric yarn are fed through the air jet when the crimp in the textured covering yarn is maximized.

12. The method of claim 10 wherein the polymeric yarn ends are stretched when drawn through the heating zone.

13. An apparatus for forming an air covered yarn and having a heating zone, a cooling zone, and a false twist texturizer for forming an inelastic covering yarn, further comprising:

(a) a creel rack for a plurality of supply packages of elastomeric core material;

(b) an electronic tension controller for controlling the tension in the elastomeric core; and

(c) an air jet for entangling the covering yarn and the elastomeric core to form a composite air covered yarn.

14. The apparatus of claim 13 wherein the creel rack is mounted on the apparatus.

15. The apparatus of claim 13 wherein the creel rack comprises a plurality of creels positioned on substantially the same level.

16. The apparatus of claim 15 wherein each of the plurality of creels are angled inwardly toward the electronic tension controller.

17. The apparatus of claim 13 where the size of the air covered yarn is not limited by the size of the supply packages of elastomeric core material.