US2649623A

US2649623A - Method and apparatus for stretchbreaking textile filaments

Info

Publication number: US2649623A
Application number: US753197A
Authority: US
Inventors: Jr Robert M Ingham
Original assignee: Milliken Research Corp
Current assignee: Milliken Research Corp
Priority date: 1947-06-07
Filing date: 1947-06-07
Publication date: 1953-08-25
Anticipated expiration: 1970-08-25

Description

Aug, 25, 1953 R M. lNGHAM, JR

METHOD AND APiARATUS FOR STRETCH BREIAKING TEXTILE FILAMENTS Filed June 7, 1947 2 Sheets-Sheet 1 76 v 7 z 8 4 J 6 7 a 9 1a A i .Z. O T 26 C9 W GENERATOR 7/? I Tilil.l.

R TOR GENE A .30

INVENTOR 'ROBERT M. INGHAM BY W ORNEY Aug. 25, 1953 R. M. INGHAM, JR 2,649,623

METHOD AND APPARATUS FOR STRETCH-BREAKING TEXTILE FILAMENTS Filed June 7, 1947 2 Sheets-Sheet 2 Tic r.

INVENTOR ROBERT M. INGHAM Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE.

METHOD AND APPARATUS FOR STRETCH-- BREAKING TEXTILE FILAMENTS Robert M. Ingham, Jr., Clemson, S. 0., assignor to Deering Milliken Research Trust, New York, N. Y., a, nonprofit trust of New York Application June 7, 1947, Serial No. 753,197

13 Claims. (01. 19-.37)

The present invention relates to the treatment of continuous textile filaments for production of sliver, roving or yarn therefrom and comprises an improved stretch breaking process for conversion of a tow of continuous filaments, such as rayon tow, into a staple fiber product of superior quality. As the improved process is particularly applicable to rayon tow, whether produced by the acetate, cuprammonium or viscose process, the invention will be described with reference thereto. It should be understood, however, that the invention is applicable to any type of textile filamentary material that may be weakened by heat, as, for example, glass nylon, vinyl or vinylidene chloride polymers or copolymers or derivatives of protenoid materials.

Conversion of rayon tow into staple fibers by stretch breaking, as heretofore practiced in the art, involves the gripping of the tow by at least two sets of rotating rolls, of which one set, the delivery set, rotates at a higher peripheral speed than that of the other, or feed set, with consequent breaking of the individual filaments of the tow during passage from the feed to the delivery rolls. Any one of the numerous drafting mechanisms ordinarily used in the textile industry for drafting staple fiber sliver and roving in the production of yarn or for reducing fiber length by stretch breaking can be used for stretch breaking tow. Such treatment of continuous filaments in a drafting mechanism is intended to cause the filaments to break randomly at different positions in the ratch with corresponding random length of staple fibers in the produced roving or yarn and consequent substantial uniformity of the product. Such intended action, however, does not materialize in practice as filament breakage, instead of being randomly distributed in the ratch, is disproportionately large near the draft or delivery rolls. This results in undesired short staple length of fibers in the roving or yarn. The concentration of filament breakage in the lower part of the ratch is believed due to interfilament friction which reduces the effective length of the ratch.

When filaments break near the lower rolls, the ends of those lengths of filaments held only by the upper rolls tend to snap up and out of the sliver and drag with them ends of other filaments which may have been broken higher in the ratch and are being advanced by the rotation of the feed rolls. There is thus presented to the nips of the draft rolls a relatively thin portion of sliver corresponding to the portion from which the broken ends have snapped back. This is followed by a thicker portion in which there is a plurality of frayed or broken ends turned back upon the sliver or projecting from the side there of. The result is improper drafting and the production of slubby roving or yarn. The succession of relatively thin and thick portions of sliver in the ratch caused by the concentration of fiber breakage near the lower rolls, occurs cyclically, giving a breathing action to the drafting and resulting in a yarn or roving of periodically varying diameter.

A further disadvantage in the conversionof rayon tow to roving or to yarn by stretch breaking as heretofore practiced is that the physical characteristics of the cellulosic material may be impaired by the necessary stretching of the filaments beyond their elastic limit.

Another object of the invention is thus to provide a method of, and means for, stretch breaking of tow into fibers of uniform and substantial staple length.

Another object of the invention is to provide a method of, and means for, converting tow into a staple fiber product without substantial im pairment of its physical characteristics.-

In accordance with the invention, both of these general objects are attained by the application of heat to the tow in the neighborhood of the feed rolls. Such application of heat concentrates filament breakage high in the ratch and thus insures fibers of longer staple length and substantially eliminates the breathing action hereinbefore described. When filaments are subjected to localized heating, the elastic limit of the heated part of each filament islowered and hence breakage will occur without stretching the entire length of filament in the ratch beyond its elastic limit. Thus, the localized application of heat high in the ratch not only insures fibers of longer staple length and more uni form roving or yarn, but also a product of improved physical characteristics as compared to roving or yarn produced by stretch breaking tow without the application of heat.

For a better understanding of the invention, reference may be had to the accompanying drawings of which: I

Fig. l is a diagram explanatory of the improved process of the invention;

Fig. 2 illustrates diagrammatically apparatus embodying the invention andadapted for dielec tric heating of the filaments high up in th ratch;

Figs. 3 and 4 illustrate the invention as embodied in apparatus for heating the filaments at thenips of the .feed rolls, and

of feed rolls, the line B, that of the nips of a pair.

of draft rolls and the lines identifiedby reierence A numerals I to H1 inclusive, ten continuous filaments in the ratch. If the filaments, as they move down through the ratch, don-example,

they pass the area l2, are subjected to heat,

sufilcient to weaken them but insuflicient to cause them to fall apart when not under tensiontthen at any moment only those filaments that are nipped by the draft rolls will be broken, and

such breaking will occur at the location of the application of :heat, In Fig. 1 therefore, rfila= ment 1 the forwardend of which is assumed to be in the nips of the draft :rolls, ,;is broken, as indicated at M, into, a fiber of a staple length egual to th distance'fr-om the draft l llsrto the location at which heat isapplied. During sues cessivejintervals of time clurins eaohzo'f whichall the filaments are advanced uniformly in the (latch, filaments 2, .3, .4, etc, are successively nipped by the-draft rolls. When filament 12 is nipped, the part thereof which was subjected to heat when filament -l broke, is cooler than the part .newly exposed to heat and breakage of the filament thus-occurs :at the heated location with the. result that the staple length of the fiber formed from filament ,2 is the same as that formed from filament l. The same is true of each .filamentin the ratch,.,s,0.long as the applied heatis insufficient to callseseparation of the filament when the filamentis not held by the pipe of both sets of rolls. If desired, to insure sufficiently rapid cooling -.of the filaments after leaving the heating zone to-prevent breakinglowerin the ratch, a. cooling. station, ,at forexample, the" location Lindicated diagrammatically at ,lfi may be ,provided.

lEig. {1 has purposely been ,madeentirely diagrammatic iniorder to make itclearwhy applicationbflocalized heating to the filaments duringstretchz-breaking resultsin the productionlof fiber of .a length substantially equal .to the distanceibetween thedraft rollsand the locationat whichtheiheat isapplied. .It will be understood, of course, that in practice, at anyone time there will'be .aplurality of filaments in theratch i corresponding'to each of the filaments I to all, of Fig. '1 and that such filaments are inabundle and .notisolated, as diagrammatically indicated.

ln-accordance with the inventi-on,.any oneojf a-varietyo'f'means may be provided for applying heat "tot-he filaments, and such means may be located =so-as to heat the filaments i h .in the ratch, or-at the nips of the "feed rolls, or just priorto entering the ratch. Fi s. 2 through 6 indicate diagrammatically such various alternative heating arrangements.

In Fig. 22. direct tow-to yarn spinner is'indicated diagrammatically as including a pair of feed rolls its, .a pair of 'draftrolls '20 and a spindle carried bobbin 22.with its associate'dspinning ring 24. .The feed rolls draw tow'26 'fromany (suitablesupply'reel (not shown) and feed-it-into the ratch-where it is converted into fiber-f -staple lengthand draftedby the rapid rotation-of draft :rollss2fl. In'accorda'nce with the invention, the filaments, as they ileave the-feed rolls :18 pass between a pair of plates 28. Plates 28 are connected to a radio frequency generator 30. The filaments thus form the dielectric of a condenser and will be heated by the high frequency electrostatic field set up between the plates 28 by the generator 30. The temperatur of the file.- ments may be raised sufiigiently to cause breakageof those filaments nipped :by both sets of rolls, as explained in connection with Fig. 1.

, "Ilhe filaments, upon emergence from between the plates 18 may b cooled, if desired, as by a cool sjtp eam supplied by a blower 32.

' 'Instead of providing separate condenser plates, :as Fig. 2, :the deed rolls themselves could be constructed as-elec'trodes and connected to a high frequency generator as shown in Fig. 3. In Fig.

- 1.43118 drivendeed roll Ida has a conducting sur- 'face, as of copper and the tow 25 is wrapped well around the surface of this roll, as by passage around a small idler 34 positioned near the lower surfaceof roll law. A latively mal idler d 01 d8] has a co duct c o soon r an insulat ng esil ent oa ne p lye h ene or -t o ike. T e olls I M and 8 a e c n-nes ed a by brushes .(not shown) to the generator 3!). By wrapping the tow well around :the roll la the pressure between the rolls iBa and i812 .ean be e l s o s to prevent dama t t e insulatins surfac of roll lab- W h his ar angement, the heat is concentrated ,at [the nips ,of the fo d rolls and i he fi am nts ra he han in the rolls and cots. If desired, cooling means, as in Pig. 2 could be provided. I

,In Fig. than alternative arrangement for heat ing the tow at the .nipsofthe feed .rolls is illustrated. In this embodiment of tneinvention, the idler roller 180.01? :the feed r0115 has .a'stationary hollow shaft 4.3.5 and anouter shell 38 rotatably supported thereon as by ball bearings A9. A h a n c l 42 s n1 2i1 toc1on. the shaft ,35 s as to transfer heat to the shell 38, This arrange? m rit has the d fintage that electrical connections to movin partsare :not needed.

lnF s- 5,- a .pai f b ow r 414 d rect st oamso hot gas, such as .a r. ont th tow hig n th rat h and .in F .6, thetow. iu b o enter n the hips ,of the feed rolls, passes by .a battery ,Qf infrared lamps 4.6. It wil be under to dha the stre ms ethoteas .from bl wers A4 .o ;5 are conc n rat d .22 t p y eatov Melatively restrictedarea and that the lamps .46 .of Fi .fiar rowerfulienoush n cl se e ugh to hefe d rollss that .the h a ta ned by th tow when it ntors the nips of h f ed rolls will besufiioiont toinsurs breaka e o .filament h ld y oth'f and draft/r ll .1...i I i n as .n w b en described with refer noat various embod ment thereof. Ob: vi u lm o e od ea in filamen s n accordanoe with the i venti n .to insure br aka e at reduced n n an n oifi srs o substantiall r n ue o dib f e e b me ns othe thantho s fio l cdos i d her n- ,Inpra ticingt e inventi n, it is nly n cessar t a ths heat applied tothe filaments be localized, berelativelyrapidly dissipated and be sufficient to cause breakage when the filaments are subjected to tension. -'The heat should not be great enough to cause-permanentalteration ofthe physical characteristicsofthe-material. h V V Whilethe invention'has been described in connection with a direct tow-to-yarn spinner, the method and means of the-mvention are; not con corned with=the particular -'for -r n of staple fiber product thatis, whether it is in the form of yarn or of -roving, nor is the invention necessarily limited to the treatment of artificial, as distinguished from natural, filaments or fibers as the invention may be advantageously employed for stretch breaking of any filamentary material which is thermoseverable and of a length greater than that of the ratch. While in the particular embodiments of the invention illustrated and described, the heating station has been indicated as stationary and as in continuous operation, obviously, if desired, the location of application of heat could be varied at will or heat could be applied intermittently, with corresponding change in length of the produced fibers.

The application of heat and moisture to tow during a stretchbreaking operation is disclosed and claimed in the co-pending application of Donald G. C'. Hare, filed June 20, 1947, Serial Number 756,069, and assigned to the assignee of this application.

The following is claimed:

1. Apparatus for stretch breaking textile filaments comprising in combination, a stretch breaking mechanism including feed and draft rolls defining a ratch therebetween, means in the neighborhood of the feed rolls for heating the filaments whereby breakage of the filaments occurs high in the ratch and means for dissipating the heat applied to the filaments by said heating means.

2. The apparatus of claim 1 wherein said heating means comprises a means for dielectric heating of the filaments during passage between the feed rolls, said means including a generator of high frequency oscillations connected to the feed rolls for setting up a high frequency electrostatic field for passage of the filaments therethrough.

3. In a direct tow-to-yarn spinner of the type having spaced feed and draft rolls defining a ratch therebetween, the improvement comprising heating means for the tow located in the neighborhood of the feed rolls and adapted to apply heat to the tow sufficient to cause breaking of the filaments of the tow when tensioned and ripped by both draft and feed rolls but insufiicient to cause severance of filaments not so tensioned and means for cooling the tow subsequent to the heating thereof by said heating means, to insure filament breakage at a predetermined distance from the draft rolls.

4. The method of stretch breaking a continuity of substantially parallel textile filaments during passage through a zone which comprises feeding the filaments into the zone at one rate while withdrawing the filaments from the zone at a greater rate to tension the filaments, maintaining the filaments substantially parallel during passage through the zone and applying to the filaments in the nighborhood of the entrance into the zone heat suflicient to cause breakage of tensioned filaments but insuificient to cause severance of untensioned filaments.

5. The method according to claim 4 wherein heat is applied to filaments after entrance thereof into the zone.

6. The method according to claim 4 wherein heat is applied to the filaments during entrance into the zone.

7. The method according to claim 4 wherein heat is applied to the filaments prior to entrance thereof into the zone.

8. The apparatus as in claim 1, wherein said heating means comprises located means for generating infra-red rays.

9. The method according to claim 4 including cooling the filaments in the zone at a location in their path beyond that at which heat is applied.

10. The apparatus as in claim 1 wherein said heating means comprises an electric heating coil carried by one of said feed rolls.

11. The apparatus for stretch breaking textil filaments comprising in combination, a stretch breaking mechanism including feed and draft rolls defining a ratch therebetween, aligned spaced conducting plates positioned on either side of the ratch adjacent the feed rolls, a high frequency generator connected to said plates for setting up a high frequency electrostatic field between said plates whereby heat is applied to the filaments and means for directing a current of air against said filaments after passage through said field in order to cool the same.

12. The apparatus as in claim 1 wherein the said heating means comprises means for directing a stream of a hot fluid medium against said filaments.

13. The method of treating textile filaments which comprises stretchbreaking the filaments in a drafting mechanism while locally heating the filaments in the neighborhood of their entrance into the ratch and subjecting the filaments to forced cooling immediately following said heating to cause the filaments gripped by both sets of rolls of the mechanism to break near the feed rolls.

ROBERT M. INGHAM, JR.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain of 1873