US3439391A - Apparatus and method for edgecrimping and/or heat treating yarn - Google Patents

Description

April 22, 1969 B. M. DE VORE ET AL 3,439,391

I APPARATUS AND METHOD FOR EDGE CRIMPING AND/OR HEAT TREATING YARN Filed Sept. 20, 1965 Sheet INVENTORS BA NA R o M. DEVOR E JA MES E F0 w LE R y WILLIAM P.WARTHEN ATTORNEY April 22, 1969 B. M. DEIVORE ET AL APPARATUS AND METHOD FOR EDGE CRIMPING AND/OR HEAT TREATING YARN Sheet 2 of 3 Filed Sept. 20. 1 965 BAINARD M. DEVORE JAMES E FOWLER ATTORNEY April 22, 1969 B. M. DE VORE ET AL 3,439,391

APPARATUS AND METHOD FOR EUCE CRIMPING AND/OR HEAT TREATING YARN Sheet 5 of 5 Filed Sept. 20, 1965 INVENTORS BAINARD M. DEVORE JAMES E.FOWLER BY WILLIAM P. WARTHEN ATTORNEY United States Patent 3,439,391 APPARATUS AND METHOD FOR EDGE-CRIMPING AND/0R HEAT TREATING YARN Bainard M. De Vore, James E. Fowler, and William P. Warthen, Spartanburg, S.C., assignors to Deering Milliken Research Corporation, Spartanburg, S.C., a corporation of Delaware Filed Sept. 20, 1965, Ser. No. 488,590 Int. Cl. D02g 1/08, 3/00; D02j 13/00 U.S. Cl. 28-1 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus and method is disclosed for development of crimped thermoplastic yarn including heating thereof within a channel disposed in a plurality of loop coils within a heating zone while simultaneously passing a stream of gas through said zone to preheat same and utilizing the gas to positively overfeed the yarn to and through the channel.

The present invention concerns an apparatus and process for heat processing a running length of either monofilament or multifilament yarn.

This invention also relates to stabilizing or developing a running length of thermoplastic yarn by the application of heat.

The invention is more particularly concerned though not essentially so with apparatus that acts on a continuous running length of yarn including thermoplastic continuous filaments.

This invention is also concerned with preliminarily drawing and deforming a thermoplastic yarn, for example by crimping, and subsequently developing and/or stabilizing the yarn.

This invention relates to heat treatment of thermoplastic yarn that has been optionally texturized or otherwise subjected to deforming force so as to impart to the yarn latent or actual stress and subsequently contracting the yarn in a heated zone so that yarn development and/ or stabilization may be accomplished.

In the manufacture of texturized thermoplastic yarn it is customary to subject yarn to a deforming treatment such as edge-crimping, stutter box crimping, false twisting or other processes designed to deform yarn. Subsequent to such processes it is often desirable to subject the thermoplastic yarn to a heat treatment under relatively low controlled tension prior to use in manufacture eg of woven and knitted fabrics. Such heat treatments tend to stabilize the yarn so that fabrics constructed from such stabilized yarn have less tendency to shrink or stretch in use. The reason such stabilization is necessary is probably because latent stresses are produced in the yarn during the various processing steps to which it is subjected prior to final use e.g. drawing, crimping, or bulking operations. In use, these stresses manifest themselves by changes in the configuration of yarn or products prepared therefrom. The purpose of the heat treatment is to release these stresses under controlled conditions. Where, for example, a yarn is edge-crimped and the edge-crimped yarn is removed from the machine (no heat treatment after leaving the blade) in a semi or unrelaxed state the crimp level appears to be very low and the diameter of the coil large (due to immediate elastic recovery of shrinkage face). When the yarn is further relaxed the crimp will assume a smaller helical diameter. If in the completely relaxed state the yarn is subjected to elevated temperature, boiling water or dry heat the yarn will shrink on the innerface of the helix and also along the fiber length. Therefore, development is defined for pur- 3,439,391 Patented Apr. 22, 1969 ice poses of this application, as subjecting the yarn to elevated temperatures either in dry heat or boiling or near boiling water, thus allowing the yarn to proceed from a large, lazy coil to a more elastic smaller one.

An edge-crimped yarn which has been completely relaxed and subjected to elevated temperatures would already have developed maximum bulk and would not further shrink during finishing of carpets or fabrics. If the crimped yarn that is not developed or stabilized is tufted into a carpet or put into a fabric, maximum shrinkage or crimp development will take place during finishing of such articles and is of little value.

In order to get a valuable yarn, controlled shrinkage is necessary. The apparatus and method of this invention accomplishes this result and yields a yarn having maximum bulk and good cover.

It is known in the prior art to stabilize and/ or develop yarn by overfeeding the yarn into a heat processing zone so as to heat the yarn to a temperature between its glass point i.e., its second order transition point and its sticking temperature. The degree of overfeed is determined by its properties desired in the finished product. It has also been suggested to subject the thermoplastic yarn which has been texturized, for example by some form of deformation such as false twist, stuffer box or edge-crimping to stabilization treatment by running the yarn through a heated zone under controlled overfeed.

The prior art processes where yarn is overfed to a heated zone by means of conventional feeding devices have led to numerous problems. The first and probably one of the most important problems encountered in conventional developing and stabilizing operations is that the treated yarn is seldom developed to exactly the desired degree and is not adequately stable as a result of the texturizing or bulking step alone. It has also been found that merely heating yarn at an elevated temperature while the yarn is under no controlled tension may produce too much contraction, i.e. over-development or excessive shrinkage. To achieve the desired degree of bulking or contraction in yarn it is necessary to overfeed the yarn a selective amount into a heat processing zone.

Another problem that is encountered when conventional feed devices are used to advance yarn into or through a heated zone is that the tensions necessarily involved in such an operation will tend to pull some of the texture, bulk or crimp out of the yarn thereby destroying the textured etfect. In the conventional feeding of yarn to a heated zone problems arise in continuously feeding the yarn into the processing zone, especially at a high velocity as the yarn tends to become entangled in the overfeeding equipment rather than proceeding in a proper manner into the heat processing zone due to the very low force urging the yarn into the zone.

Another problem which arises in the development of crimp, particularly latent crimp of multifilament yarn, is that the yarn tends to band i.e. several filaments cling together so that the crimps remain in phase with each other thus reducing the bulkiness of the yarn at that point. This problem increases in severity along with increased yarn velocities. The consequence of such banding is the lack of uniformity of the yarn in the products produced therefrom.

It is therefore an object of this invention to provide a novel method and apparatus for development and/or stabilization of thermoplastic yarn that may be, but is not necessarily texturized or deformed in some way prior to stabilization and/ or development.

It is also an object of this invention to subject thermoplastic yarn to heat treatment, including crimping, bulking, or the like with subsequent development or stabilization.

A still further object of this invention is to provide methods and apparatus for first crimping a yarn and overfeeding such yarn into a heat processing zone at low tensions.

It is still another object to provide methods and apparatus for overfeeding monofilament or multifila'ment thermoplastic yarn at high velocity and low tension after crimping into a conduit type processing zone.

It is still another object of this invention to provide an apparatus and method for drawing, texturizing and post treating a running length of yarn in a continuous operation at high velocities. Other objects will be apparent to those skilled in the art in which this invention pertains.

In describing this invention, the following definitions and explanations will be helpful.

By stabilization is meant subjecting a controlled length of yarn to the required temperature and time in order to control further shrinkage to the desired level during finishing of the articles made therefrom.

The stabilization of a textured yarn refers to the heat setting of the crimp in the desired geometric configuration. A fully developed or relaxed yarn can be heat set in that state or in any condition of extension between the fully developed and the straightened configuration. Normally, fully developed yarns do not yield optimum bulk and cover in a tufted carpet. Consequently, stabilization on the apparatus of this invention refers to the heat setting of the developed yarn with the filaments extended from the fully crimped configuration to within approximately to 40 percent of the straightened configuration.

Specific embodiments of this invention will now be described with reference to the accompanying drawings.

FIGURE 1 is a partially cut away perspective view of the developing and stabilizing apparatus of this invention.

FIGURE 2 is a diagrammatic perspective view of a drawing and a texturizing apparatus in combination with the stabilizing and/or development apparatus of this invention.

FIGURE 3 is a sectional view along line 33 in FIG- URE 1 showing the details of the preferred heating means that may be used with the stabilizing and/or developing apparatus of this invention.

FIGURE 4 is an enlarged cross sectional view showing the terminal portions of the development and/or stabilizing channel employed in the apparatus shown in FIGURE 1.

FIGURE 5 is a front view of an alternative type of channel or conduit of the stabilizing and/or developing apparatus of this invention.

FIGURE 6 is a side elevation view of the alternative type of channel or conduit illustrated in FIGURE 5.

FIGURE 7 is a cross sectional view taken along 7--7 of FIGURE 5.

FIGURE 8 is an end view of an aspirator that may be used asthe compressed gas means of this invention.

FIGURE 9 is a cross section taken along the line 9-9 of FIGURE 8.

FIGURE 1.illustrates a partially cutaway view of a particular embodiment of the heat treatment conduit or channel of this invention.

In FIGURE 1 a thermoplastic yarn 11 is fed by a gas delivery means into the conduit or channel 12 of this invention and exits after being conveyed a number of turns through the conduit or channel at the end 13 thereof.

FIGURE 2 illustrates one mode of incorporating the heat treatment conduit or channel of this invention into a unitary, continuous yarn drawing and texturizing apparatus. In FIGURE 2, yarn is fed from supply packages in input draw rolls 21, across draw pins 22, to a fiat heater 23 which may be a platen, across guide rolls 24 to crimping heater roll pair 25. In the preferred embodiment output roll 25 is heated. After passing crimping heater rolls 25 the yarn is passed over the edge of a blade 26 at an acute angle while the yarn is heated in a typical edge-crimping operation. After passing the blade the yarn is cooled on cold rolls 27, that may be water cooled, and advanced by these rolls to a compressed gas delivery means 28 at which point the yarn is conveyed by gas under pressure into the inlet portion of heat treatment conduit 29, As the yarn is transferred through the coil by means of gas under presure, it is in a substantially tens-ionless or in a controlled low tension overfed state. In this condition the compressed gas delivery means causes the yarn to billow and float through the elongated conduit while relaxed and substantially without tension or under controlled low tension. Therefore the yarn is allowed to stabilize as well as to develop, if it has been texturized before heat processing.

In FIGURE 3 the section taken along line 33 in FIGURE 1 illustrates a preferred means for heating the stabilizing or development apparatus of this invention. The conduit 30 is used to convey a gas such as air, through the heater so as to be preheated by resistance heater 31. The conduit or channel 33, that in this embodiment is in the form of a compressed helical coil is used to convey the yarn through the heating apparatus. A lining 34 of a material having a low coeifcient of friction may be used to help prevent binding of the yarn in the conduit.

In FIGURE 3 the outer walls of the conduit or channel 33 that forms in this illustration a six loop coil (approximately 2070) are in contact with a commercial The'rmon cement 36 available from Abernathy Thomas Enginering Company that transfers heat from a strip resistance heater 31 which may be coiled to assume a generally cylindrical shape. The coil 33 may be, for example, 24 inches in diameter and the conduit or channel may be made from copper in. inside diameter) tubing having an outside diameter of 1% inches and may be heated by means of 240 volts EMF at a total available power of 1500 watts. This conduit or channel is preferably lined with a low friction material such as Tefion or the like 34. Temperature controls or regulating devices 35, such as commercially available thermistors may be used in close proximity to the heating means. In order to ensure good conductivity and even heat transfer throughout the assembly a commercially available Thermon cement or similar heat transfer agent 36 may be packed in solid form around the conduit or channel. As insulation, a fiberglass blanket may be wrapped about the entire assembly either inside the aluminum foil wrapping 37 or it may be wrapped about the exterior of the aluminum foil.

FIGURE 4 illustrates a cutaway view of the yarn as it enters and exits from the conduit. As the yarn 40 is fed into the conduit without substantial tensioning it billows in a lose fashion and as it proceeds through the conduit is at all times carried through the conduit or channel by the compressed gas.

FIGURES 5 and 6 illustrate an alternative form of stabilizing and/or developing conduit or channel wherein the continuous conduit or channel is cast from metal rather than being formed from tubing. In either case the elongated conduit or channel will usually vary in length between approximately 5 and 100 feet and is perferably lined with a coating or tubing of a low friction material such as nylon or Teflon in order to give a surface with a low coefi'icient of friction. In FIGURE '6 the liner of low friction material is illustrated at 61 and an appropriate cover 62 for the channel or conduit may be provided.

In FIGURE 7, which is a cross-sectional view of the channel shown in FIGURE 5, the preheating conduits are cast in the wall of the heating apparatus.

FIGURES 8 and 9 illustrate a two-piece aspirator or compressed gas delivery means that may be used in connection with the heat treatment apparatus of this invention. Part A is made up of a cylindrical forward section and rearward section 91. Each section has aperture vanes therethrough, the aperture in section 90 having a flared front portion 92 that communicates with a cylindricai portion 93 that is in communication with a bore of even larger diameter 94 through the body of forward section 90. Part B of the aspirator, the rearward section 91, constitutes an insert for part A having a generally cylindrical forward portion 95 with a slotted portion of a larger diameter 96 having four uniform slots 97 or vanes, best shown in FIGURE 8, therein to allow the passage of the compressed gas and an intergal section 98 that is connected with a gas connecting channel portion 99. A bore 100- of a fairly uniform diameter passes through the entire portion. In operation of this device assembly rearward portion 91 fits into the slot 94 in the forward portion 90 so that compressed gas when it enters around cylindrical element 95 is forced forward through the vanes thereby creating a venturi effect in the vicinity of cylindrical element 95 so that vacuum is created in the area of element 95 thereby transporting or conveying the yarn forward in the direction or motion of the compressed gas. This particular aspirator is of particular value in this invention because it delivers an essentially twist free yarn to the heating apparatus of this invention. This is true because the gas delivery vanes 97 are equally spaced apart and are usually at least four (4) in number.

In the operation of the heat treatment apparatus of this invention as shown in foregoing FIGURES l9 any man-made thermoplastic yarn of any denier may be beneficially treated regardless of whether it has been previously deformed or texturized, at least as to stabilization, by passage through the elongated heated conduit or channel of this invention.

In the operation of the apparatus shown in FIGURE 1 any man-made thermoplastic yarn 11 is fed by means of a compressed gas delivery means 10, that may for example be an aspirator or capillary tube, into the body of the conduit or channel 12. The channel may be wound into a convenient form such as a helical coil that may be situated in either a horizontal or a vertical plane. The shape of the coil may be generally circular or elliptical or any other convenient shape so long as the yarn path does not include any sharp bends.

The inside diameter of the channel will, of course, vary with the denier of the yarn that is being stabilized or developed. For example, with a yarn in the range of 1000 to 6000 total denier usually having from 1 to 100 filaments, the inside tube diameter will vary from approximately inch to 1 inches. These deniers and figures are certainly not critical and may be varied depending upon the final properties of yarn that is desired.

The length of the channel that may, for example, constitute a coiled tube as shown in FIGURE 1 or a serpentive shaped conduit or channel will usually vary between 5 to 100 feet in length, generally speaking, and will usually compriseone continuous conduit or channel compressed so as to constitute from 2 to 10 parallel wraps or rings (approximately 720 to 3600") for the conservation of space. The overall shape of the heat treatment channel of this invention will most generally be that of a circular or elliptical or U-shaped coil. Other convenient configurations may be used so long as no sharp bends are encountered. The radius of the coil, if a coil shape is utilized will vary in most instances between 6 inches and 4 feet. In the operation of this yarn heating device, the yarn 11 is conveyed by compressed gas delivery means 10 such as an aspirator into the body of the conduit 12 in an overfed condition or in a controlled low tension condition. The yarn after being overfed through the heat treatment apparatus by means of gas under pressure exits from the end of the channel 13. A conduit 14 is provided for admitting gas to conduit 30 (FIGURE 3) to be preheated that after preheating is used to convey yarn through the device of this invention.

In the preferred embodiment the conduit 12 is formed of a generally good heat conductor such as copper, stainless steel, Monel metal, brass or any equivalent metal or metal alloy and is lined with a material having a low coefiicient of friction. This innerlining of a low frictional material may constitute a coating intergal with the metal conduit or channel or it may constitute a separate member such as a tube. The innerlining 34 which is shown best in FIGURE 3 is preferably a smooth material having a low coefficient of friction such as Teflon or other equivalent halogenated thermoplastic material. Other equivalent materials may be used such as Mylar, nylon, glass or the like, that do not decompose or deteriorate at the selected processing temperature. In the preferred embodiment an aspirator or other equivalent means for providing a gas under pressure to aid in feeding the yarn to the channel may, optionally, be attached to the entrance end of the conduit. This aspirator serves to deliver gas under pressure to move the yarn through the channel and also creates turbulence in the channel that causes the yarn to billow.

Any man-made thermoplastic yarn that may be treated beneficially by the apparatus and process of this invention and may, for example, be nylon, polypropylene, polyester including polyethylene terephthalate, Kodel or blends or mixtures of these may be used. It should be understood that these fibers are merely illustrative of those now feasible and that obviously many others may be beneficially treated by this process and apparatus.

The yarn velocity through the conduit will vary between approximately 25 yards per minute or up to and including a thousand yards a minute or even higher. The most preferred range would be from about to 800 yards per minute.

The velocity of compressed gas as introduced through compressed gas delivery mean-s varies usually in the range from approximately 1000 to 6000 feet per minute, which will correspond to a general range of from 5 to 50 psi. gauge. The compressed gas is most preferably preheated. Although any conventional means may be used to preheat the compressed gas, the means shown in FIGURE 3 comprising a small conduit or series of conduits 30 that pass through the heat treatment zone in close proximity to or in contact with the heating means is preferred. FIG- URE 3 also illustrates that the compressed gas that serves as a carrier for the yarn through the stabilizing and/or developing 'tube is preheated to approximately the same temperature at which the stabilizing and/or development tube is maintained. The compressed gas is usually heated to a temperature in the range of approximately 200 to 500 F.

In order to realize fully the complete benefits of the heat processing apparatus and process of this invention, the yarn Whether it be multifiament or monofilament is preferably overfed into the entrance to the channel, usually in the range of 3 to 30%. Quantities or percentages of overfeed below or above this range, however, can be used as desired. Another Way of stating this quantitative figure is by saying the yarn is withdrawn from the exit of the conduit or channel at a rate of 3 to 30% less than the rate at which the yarn is fed into the channel. The means and degree if overfeed into the conduit or channel of this invention should be such that the yarn is pushed or stuffed into the entrance and is not pulled by shrinkage.

A short section of yarn or any one point along a given length of yarn will usually dwell within the heating conduit for a length of time varying 1% seconds to approximately 10 seconds. Since the dwell time in the unit is somewhat a function of the temperature, velocity and denier of the yarn being treated, all these factors must be considered. For example, when yarn is being stabilized and/or developed at a lower temperature, for example, F, the yarn being a medium denier yarn having a total denier of, for example, 2000, the velocity of the yarn may be increased to say, for example, 500 yards per minute. On the other hand, where a high denier yarn, for example, a yarn of 4000 to 6000 total denier is run, a higher temperature, for example 400 -F. may be utilized at a velocity ranging from 500 to 1000 yards per minute. These factors may be worked out by the operator depending upon the level of stabilization, i.e. actual shrinkage, or the level of development i.e. crimps or other forms of distortions per inch that are desired.

(outside diameter) copper tubing formed into a coil of approximately six turns (2070). The tube was lined with a /s-inch outside diameter Teflon tube having a wall thickness of 0.035 inch. Nine pounds of this yarn was run having a pulldown level of 38.6% with a final The heat treatment conduit should be maintained in 5 average denier of 2635. The carpet produced from this an insulated container and most preferably is operated yarn had good shrinkage properties, indicating that the at a temperature in the range of 200 to 500 dependdevelopment and stabilization accomplished was very ing upon the particular type of yarn that is beigg pfocsatisfactory. essed. In no event should the temperature of the eve oping and/or stabilizing tube be so high as to deleteriously l0 EXAMPLE HI affect or degrade the yarn that is being processed. These A 3-ply, 300-filarr1ent gear crimped yarn (Merge A896- temperatures will vary considerably for yarns of a par- 1) havlng an origlnal denier of 3860 was run through a ticu'lar composition, for example, when polypropylene is tenslon devlce into a cold roll and then into the channel processed, exit gas temperature at a velocity of 200 yards f thls lnventlon at a rate of 400 yards per mi ute, Th per minute will usually vary between 260 and 310 F; temperature 1ns1de the channel was maintained at 270 for polyester (Dacron) or nylon 6 the exit gas tempera- F. The yarn was overfed at a rate of from the cold ture will usually vary between 360 F. and 390 F., for roll to the nip roll, i.e. the nip roll was running at the nylon 66 the exit gas temperature will usually vary ber te Of 320 yards per minute. The pull dow f thi tween 400 and 450 F. 20 yarn was 33 /2 percent. This example clearly demon- The following examples are illustrative of the inven- Strntes that a y rn texturizcd by gear crimping can be tion and of the results obtained thereby but should not be stabilized by the use of the heat development channel considered as limiting. On the contrary, it will be underof this invention. stood that persons skilled in the textile and yarn process- Having thus described the invention, that which is ing arts will be able to make many variations and modificlaimed is: cations of this invention not specifically described herein 1. Apparatus for processing a running length of therwithout departing from the spirit of this invention. p astic yarn, comprising yarn supply and yarn take-up means, an elongated narrowchannel disposed in a plural- EXAMPL I ity of loop coils, gas transferring and preheating means in The number of yarns of different composition were first C1956 P i y With and adjacent the P of Said D edge.crimped by f din yam f om a supply package t colls, heating means to heat said channel and said gas the input draw roll across the guide roll to a flat heater, transferring and pr h ating {means to a selected mmoperating in the temperature range f 1 0 to 320 F perature to heat sald yarn while 1n said channel and gas across guide roll to crimping heater rolls and drawn in 3 gas tralgsfemhg 111633115 to a tempel'htllffi tw n across the edge of the blade at an acute angle, while 200 500 -s an h p fl d to said gas heated. After passing the 'blade the yarn is cooled on a transferhlng and Preheatlng means Positioned Within cold roll and is advanced by this roll to a compressed an openlng 0f channel to PTOVlde a Stream f heated gas delivery means, and conveyed by gas under pressure g through 831d hhanflel, Y advancing ns to posiinto the inlet portion of the heat treatment conduit or tljlely Oveffeed y o S d channel at very low tenchannel of 'this invention. The helically coiled channel 40 51011 at a rate greatel" than the rate ald yarn is withmade up of from four to five parallel turns, through drhwn from 831d Channel, and yarn advancing nlfians 0 %-inch I.D. copper tubing varying in length from 30 to Wlthdraw Y from Sald channel- 42 feet. The yarn was overfed through this tube at a 2. The apparatus of claim 1 wherein the channel is pressure ranging from 25 to 40 p.s.i. yielding a velocity ined with a material having a low coefiicient of friction. .thr u-gh th b varying b t e 100 d 400 yards er 45 3. The apparatus of claim 2 further characterized minute, The variables of this example are set forth in n that the material is polytetrafluoroethylene, Table 1. Percent pulldown set forth in this table should 4. The apparatus of claim 1 further characterized in be considered to be the equivalent of or directly proporthat the apparatus includes edge-Crimping means stional to shrinkage and stabilization experienced in the Posed between Said y pp y means d S elondevelopment and/or stabilizing conduit or channel. gated narrow channel and the length of the channel i TABLE I Denier Number Inlet Yarn Conduit Exit Crirnps after Quau- Percent Yarn Cross section Denier of air velocity, temp., a1r Channel per stabilizing tity ullfilaments (p.s.i.) ydJmin. F. (I .s.1.) me and (1bs.) own developmg 3/ Et i%t%:t"r 3:553 83 i8 38 228 23 513% 542533;? 3? 3:533 $3 38 y 4,420 68 40 200 300 30 2 070 (241.0.) 7.5 2,382 2.4 30

4, 430 00 40 200 450 30 1, 350 i.d.) 8.5 1 1,02s 21.7 30-35 (0) Polypropylene do 1,875 70 35 200 270 2,070 (%i.d.) 11.9 2/1,250-7o s0 35 (I) Polypropylene do 1,887 70 40 400 285 2,070 @4141.) 16.4 3/l,33070 37 35 (g) Polypropylene do 3, 544 68 40 400 260 70 1.d.) 15.0 ,635 18 35 (11 Nylonfi Trilobal 4,400 as 25 200 320 05 1,350(%1.d.) 7.3 1,887 2.2 33

EXAMPLE I I between 5 and 100 feet, having an inside diameter of Polypropylene yarn having 68 filaments and a denier ranging between 3544 and 3567 of a generally round cross section was passed through a drawing-crimping aplparatus wherein gears were set at (a) 57, (b) 87, (c) 122, (d) 30%, three wraps around the output draw roll, six wraps around the hot roll at a crimping speed of 400 yards per minute. The blade diameter was 8.5 inches, the hot roll temperature 220 F. The yarn after being drawn and crimped passed over cold roll i.e., essentially room temperature was forced by air under pressure, 40 psi. gauge, into a conduit made of at least three-quarter inch.

5. The apparatus of claim 1 further characterized in that the aspirator is equipped with equally spaced apart gas vanes.

6. A method for processing at very low tension a running length of thermoplastic yarn which shrinks substantially in length when heated, comprising positively overfeeding said yarn into a heat processing zone with a stream of gas moving in the same direction as said yarn, advancing said yarn through said heat processing zone in a plurality of loop coils, heating the yarn being 4- advanced through said heat processing zone to a tem perature between 200 and 500 F., and simultaneously passing a stream of gas through said heat processing zone to preheat same prior to its use in overfeeding said yarn as specified.

7. The method of claim 6 wherein the yarn is a multifilament yarn supplied to said heat processing zone at a velocity in the range of 100 to 1000 yards a minute at an overfeed of 3 to 30 percent.

8. The method of claim 7 wherein the yarn be processed comprises polypropylene.

9. The method of claim 7 wherein the yarn being processed comprises nylon.

10. The method of claim 6 further characterized in that a given section of yarn will remain in the heat processing zone for a time in the range of /2 to seconds.

11. The method of claim 6 further characterized in that the yarn being processed is an edge-cri mped yarn.

12. A method for processing at very low tension a running length of multifilament thermoplastic yarn havin a total denier ranging from 100 to 10,000 which bulks or shrinks substantially in length when heated, compris ing subjecting said yarn to a deforming treatment, positively overfeeding said yarn at a rate varying from 3 to 30% at a velocity between 100 and 1000 yards per minute into a heat processing zone, with a stream of gas moving in the same direction as said yarn, advancing said yarn through said processing zone in a plurality of coils for a length varying between 5 and feet suflicient to heat said yarn at .a selected velocity at a temperature between 200 and 500 F., and simultaneously passing a stream of gas through said heat processing zone to preheat same prior to its use in overfeeding said yarn as specified.

References Cited UNITED STATES PATENTS 2,468,081 4/ 1949 Koster. 2,584,043 1/ 1952 Oberly. 3,241,212 3/1966 Evans et al. 3,292,231 12/ 1966 Epstein.

FOREIGN PATENTS 630,693 11/ 1961 Canada.

ROBERT R. MACKEY, Primary Examiner.

US. Cl. X.R.

UNITED STATES PATENT OFFICE Certificate Patent N 0. 3,439,391 Patented April 22, 1969 Bainard M. De Vore, James E. Fowler and William P. Warthen Application having been made jointly by Bainard M. De Vore, James E. Fowler and William P. Warthen, the inventors named in the patent above identified, and Deering Milliken Research Cor oration of S rtanburg, South Carolina, a. corporation of Delaware, the assignee, for tlie issuance of si. certificate under the provisions of Title 35, Section 256 of the United States Code, deleting the names of James E. Fowler and William P. Warthen from the patent as joint inventors, and a showing and proof of facts satisfying the requirements of the said section having been submitted, it is this 28th day of October 1969, certified that the names of the said James E. Fowler and William P. Warthen are hereby deleted from the said patent as joint inventors with the said Bainard M. De Vore.

[SEAL] EDWIN L. REYNOLDS, First Assistant Uommz'ssioner of Patents.

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