US2597999A - Strand bundle drier and conditioner - Google Patents

Description

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D, Nvmm W. A. KNOPP May 27', 1952 STRAND BUNDLE DRIER AND QDNDITIONER Filed April '7, 1948 Patented May 27, 1952 UNITED STATES TENT OFFICE STRAND BUNDLE DRIER AND CONDITIONER Wallace A. Knopp, Parkersburg, W. Va., assignor to American Viscose Corporation, Wilmington, Del., a corporation of Delaware 12 Claims.

This invention relates to a method and apparatus for drying, straightening and otherwise conditioning lamentary materials, particularly a material such as a continuously moving rayon tow.

Rayon in the form of a continuous tow is finding increasing commercial acceptance among manufacturers such as those who process staple fiber, or who make special grades of paper or various other fibrous products of special utility. The quality and usefulness of the tow is dependent to great degree upon properties such as the straightness of the laments, moisture content, particularly'the uniformity thereof, and shrinkability. A usual and customary treatment for preparing a wet continuous flamentary material such as a textile tow is carrying the material while in a `-relaxed condition through a dryer on a beltlike conveyor. The principal disadvantages of this method of the treatment is the crinkly and tangled condition of the filaments and the difficulties encountered in subsequently processing such a material.

Some of the principal objects of the invention are to provide a fllamentary material having a uniform moisture content, relatively straight filaments free from kinks and tangled masses, and such shrinkability as the trade may desire. and especially to provide a rayon tow having these properties; also to provide a process for imparting these properties to fllamentary material whether they are in an initially wet or dry condition, and to provide apparatus for carrying out the process. Other objects, features, and advantages of the invention will be apparent from the drawings and a description of the invention.

In the figures of the drawing illustrative of the invention:

Figure 1 is a longitudinal cross-section, as viewed from one side, of a preferred embodiment;

Figure 2 is a longitudinal cross-section,v as viewed from one side, of a modified structure according to the invention;

Figure 3 is a tranverse cross-section, of the modified structure of Fig. 2 taken along line III-III;

Figure 4 is a cross-section, taken on line lV-IV of Figure 3; and

Figure 5 illustrates a pair of yguides for supporting a filamentary bundle.

The invention, in brief, comprises a method for reducing the moisture content of a running filamentary material to a point at which substantial uniformity in the moisture content is established, and then subjecting the material to a humidifying process to raise the moisture content or to bring it into equilibrium with the moisture carried by the atmosphere while also subjecting the material to a filament straightening and/or stretching operation. Straightening of the filament is carried out in one embodiment by an operation which will be referred to as flufngf wherein a running tow of textile material is subjected to air current applied transversely to unsupported sections of the material extending between spaced g-uides. As an alternative operation a dried unstraightened tow may be drawn while under appreciable tension over a series of perforated plates disposed between intake rolls and output rolls.

The drier and conditioner for a strand bundle, as shown in Figure 1, is divided into three principal zones I, II and III. The Zones of this iigure are all similar in construction except for length and capacity. Perforated plates 20 are disposed progressively along a zigzag path and rolls 2| are so disposed that the periphery of each roll is tangential to a projection of the surfaces'of a pair of converging plates 20. The structure formed thereby provides a continuous support throughout the entire length of the drier for a strand bundle I8 such as a textile tow or multiple yarn material. The various zones are supplied with inlet air through the manifolds 23. These manifolds may differ in length or capacity according to the requirements of the zone to which they supply air. Air is carried from these manifolds through the flared ducts 24 to regions formed by greatest divergence between adjacent plates 20, and to the sides of the plates which form the supporting surface for the bundle. The bundle l 8 is supported on the plate surfaces facing the air inlet regions because of the greater gas -pressure necessarily maintained in these regions to obtain a desired ow of air or gas through any of the various zones. To the ends of plates 20 farthest from the air inlet regions, bailies 26 are attached to flare outwardly toward neighboring rolls 2l to form narrow passageways 28 through which air must travel after passing through the plates 20. These passageways restrict the flow of air and tend to equalize pressure conditions within the drier in the vicinity of the plates and in the lexhaust manifolds 30 which carry the air away from the drier. air or gas is promoted through all the plates and the filamentary material I3. Manifolds 30 may differ in length and capacity according to the requirements of a particular zone.

The bundle I8 is supplied to the drier by power driven intake rolls 32. Rolls 2| may be allowed to rotate freely or, if desired, all or a portion of In this manner, uniform iiow of them may be power driven. Satisfactory draft for the bundle will be furnished from a drafting means such as the rolls 34, in drier units in which the friction developed by the bundle passing over the plates 20 and around freely rotatable rolls 2l does not cause excessive tensile stresses in the filaments. In order to avoid tensileforcesV which might damage. the bundle, draft rolls such as rolls 34 may be placed at the end of each zone or they may be spaced still closer if desired to implement the transfer of the bundle. In the iinal zone, however, it is desired to subject the bundle to an accurately predetermined tension. Therefore, the linear rates at which the bundle. enters and leaves zone III will be carefully controlled by the peripheral rates of the rolls 34 and the output rolls 36 to produce a desired degree of' tension.

The air supply of each zone will be independently circulated and heated since it is desired to maintain different circulation rates and temperatures. to each zone. The heating and circulating apparatus of zones I and II may be operated, if desired, in conjunction with dehumidification devices. closely control the temperature, humidity and tension to which the bundle is subjected to effect filament conditioning according to the invention. Therefore, a gas humidifying apparatus is included in series with gas recirculating, and heat- 2 oneor more heater coils 43 andk a humidifier unit i!" 4Fcontained in. thev chamber 3.3. I'he airis then conducted` back to the conditioning unit constitoting zone IIIofFigure. 1 through a duct lmand the, manifold: 23..

As shown. inf Figure 3V the apparatus of the invention may be constructed to handle more than onel tow simultaneously over parallel paths. In this,` event it is foreseen that there will be occasions when it is desired to send but one tow through the drying and conditioning equipment. For this contingency, the hinged baffles 3'! shown in, Figure 4' operated by handles 4l extending through a compartment sidemay be used to cover the unused portion of all of the plates 20 so. that the inlet air may be channeled through the porf tion` off the plates 20 being traversed by the tow. To lace the drying and conditioning' equipment, entrances such asv the doors. 42 are provided at frequent. intervals along the sidewalls of the dryer and the conditioning units.

As an alternative apparatus for: conditioning the lamentary bundle, a highly successful apparatus is shown in Figure 2 in which the bundle is subjected to what isr hereinafterl referred to as fluing Thebundle is drawn through the zone by outputV rolls 36 throughs a series of guides 44 spaced in pairs between the guide rolls 2|. As shown in Fig. 5., the guides flatten the bundle to a band-like or flattened cross-sectional contour. Thepairs ofv guides may be distributed along the zigzag path as desired. They should not be spaced so frequently as. to cause excessive fric- .tion, whereby undesired draft. or tension must be applied to the bundle to move it through the conditioningy unit. Distances 0f' 8 to 24 niches apart.. are satisfactory. Each pair of guides 4A have opposing surfaces which are convex in the direction of movement of the bundle, as best shownin Figure 5'. Heated and humidied air is introduced. into thev unit. through a manifold In zone III, however, it is desired to 23 similar to the manifolds used on the other zones. By the baffle arrangement shown, air is forced transversely through flattened sections of the running bundle extending between pairs of guides 44. The air, in passing through the tow, iiuffs it and thereby subjects it to moderate tension while being distended laterally inthe direction of the air current. The flufling action straiglitens the fibers and untangles kinks, snarls, etc. On account of the extremely dry condition of the bundle as it leaves the previous zone, it is desired that theY bundle acquire suicient moisture content before leaving the conditioning unit soA that substantial permanent straightening of the filaments will' be obtained during the fluing action. By regulating the peripheral speeds of tension control rolls 34 and the output rolls 36 any desired tension may be maintained during fluing of the bundle.

A drier and conditioning unit such as herein described may be used on any lamentary material in continuous bundle forni by constructing the zones of any suitable length or size and by changing the operating conditions, i. e. the rate of feed, the air temperatures, the air velocities, humidication, and tensioning. Two alternative conditioning units have been shown and described for treating continuous filamentary ma.- terial. They diner structurally in that one has a perforated supporting' surface for the material as typified by zone III of Figure l while the other utilizes spaced pairs of guides; the latter construction permits the ufng action earlier referred to. While theseV umts are interchangeable if used in series operation with a drier such as one comprising zones I and II of Figure l, it will be. found that the conditioning. unit of Figure" 1Y is readily adaptable4 to being usedin series With any conventional drier wherein the running bundle is dried in4 theI relaxed state andthe bundle is consequently curly and crinkly prior to being subjected to a conditioning process'. Such lamentary bundle may then be subjected to considerable tension in the conditioning unit shown in Figure l if a high degree shrinkability is desired, while being moderately heatedv and subjected to moisturizing in a highly humid atmosphere;

The conditioning apparatus shown in Figure 2 may be operated in the manner similarto that just describedl for the unit of Figure 1 to produce a lamentary material having high shrinkability. However, it will be advantageous in some cases, and particularly when low shrinkability is desired, to obtain conditioning of the bundle while under a highly relaxed state. The unit of Figure 2 may then be employed to condition filamentary bundles which have straight filaments as the result of tension applied during a drying operation such as carried out in Zones I and II of Figure 1. In such a conditioning process, the bundle is subjected to merely'such draft as will cause it to spread laterally (as shown in Fig. 5) while passing through the guides 44 and while being subjected to transverse gas currents which enter the bundle through the flattened surfaces thereof and fluit.' the filaments passing between spaced pairs. of such guides. Such a treatment opens up the tow or., bundle, eliminates theV kinks and tangledE masses, and imparts additional straightening to the filaments without stretching any of the filaments.

The drier and the conditioning units herein described have been found tobe highly satisfactory in preparing. continuous lamentary bundles according to widely differing specifications from wet spun textile materials such'as rayon yarn 'by the viscose or cuprammonium process or yarn from cellulose acetate or other esters bywet spinning process. The apparatus of the invention is applicable also to drying and conditioning other wet spun fibers such as protein-type filaments from casein or soya-bean or other artificial or natural filaments which are subjected to i: wetting and drying during their preparation but which are preferably packaged or utilized in fabricated products in a straightened and separated condition. For example, in`

apparatus comprising zones I and II of Figure .1 in series with the conditioning `unit of Figure 2, a wet rayon tow having 200% moisture has been dried and conditioned at the rates up to and exceeding 350 feet per minute. The entire process is carried out in three stages corresponding to the three separate zones. In the first stage (zone I) inlet air is supplied at 250 to 300 F. at a velocity transversely of the tow and the perforated plates of 800 to 1000 feet per minute. In the second stage, zone II, air is passed through the tow at 150 to 250 F. at 500 to 800 feet per minute. In the conditioning unit (zone III) inlet air having a temperature of about 100 F. and having a humidity as high as is conveniently obtainable, at least above 90 percent, is passed through the bundle at 100 to 300 feet per minute. The tow is carried through the conditioning unit at minimum tension to give a nishe'd fllamentary bundle of low residual shrinkage.

The dried but unconditioned rayon tow from a conventional drier wherein the tow was dried, V f

`while in a relaxed condition on a belt conveyor, was treated in a conditioning unit such as zone III of Figure 1 equipped with the tension rolls 34 and the output rolls 36. The tow was passed through the unit at rates up to 350 feet per minute. Air having a temperature of approximately 100 F. and a humidity of 90 to 100 percent was forced through the tow at a rate of 100 to 300 feet per minute. The rolls 36 were operated at higher peripheral speeds than the rolls 34 in order to produce sumcient tension to elongate the filaments forming the tow. In this manner tows having various shrinkability ratings were produced.

On account of a rapidly developing demand for textile tow products of varying shrinkability, it is now often desired to impart specific shrinkability characteristics to the lamentary material.. Shrinkability of rayon, for example, may be controlled, as indicated hereinbefore, by subjecting filaments to a stretching operation during drying or other finishing operation. The invention is admirably suited for this purpose since the tension necessary for any desired amount of stretching may be regulated by a difference in peripheral speed of the feed rolls 34 and the output rolls 3E of either conditioning unit as shown in Figures 1 and 2, Stretching is preferably accomplished 'under conditions of temperature and humidity such as are obtained in conditioning units constructed according to this invention; stretching of the rayon tow while dry and cool may result in damaged filaments.

As shown in Figure 3 wherein two separate towsV I8 and Ia are traveling simultaneously in parallel through the conditioning unit, a plurality of tows may pass side by side through any of the drying and/or conditioning apparatus described. To those skilled in the art of drying filamentary materials, it will be seen, for example, that in treating a material capable' of withstanding higher temperature without damage. than rayon, the temperature of the air circulated through each of the several zones shown in Figure 1 may be increased and thelength of the zones shortened. In treating less heat -resistant lamentary materials lower temperatures and longer zones wouldbeemployed.

Obviously, many changes and variations can be made in the details of the invention as specifically set forth without departing from the nature and spirit of the invention as denned in the appended claims.

I claim:

l. A treating compartment for a running filalmentary material comprising means for introducing a gaseous conditioning medium into a region of the compartment near one wall, means for withdrawing the gaseous medium from a. region near an opposite wall, two oppositelydisposed sets of rolls, each set being mounted near one of the walls, for leading the material progressively back and forth over rolls of both sets in a zigzag path extending between the two regions, perforated plates supported within the compartment between successive rolls along the zigzag path so that the surfaces of the plates facing toward the gas inlet region extend in a direction tangent to the peripheries of the rolls, and extensions flaring outwardly from the end portions of each pair of plates converging toward ,a roll in the set of rolls lying closer to the gas mentary material comprising means for introducing a gaseous conditioning medium into a region of the compartment near one wall, means for withdrawing the gaseous medium from a region near an opposite Wall, two oppositely disposed sets of rolls, each set being mounted near one of the walls for leading the material progressively back and forth over the rolls of both sets in a zigzag path extending coextensively between the two regions, perforated plates supported within the compartment between successive rolls along the zigzag path so that the surfaces of the plates facing toward the gas inlet region extend in a direction tangent to the peripheries of ,the rolls, and passageways providing moderate restriction to the ow of gas passing through said surfaces and toward the air outlet region, the walls of the passageway comprising baiiles extending toward each other from plates .approaching neighboring rolls of thel same set.

3. A treating compartment for a running filamentary material comprising means for introducing a gaseous conditioning medium into a vregion of the compartment near one wall, means for withdrawing the gaseous medium from-'a region near an opposite wall, two oppositely disposed sets of rolls, each set being mounted near one of the walls, for leading the material progressively back and forth over the rolls of both 'sets in a zigzag path extending coextensively between the two regions, perforated plates supported within the compartment between succes'- sive rolls along the zigzag path so that-the surfaces of the plates 'facing toward the gas inlet 'region extend in a direction tangent to the peripheries of the rolls, a gas outlet manifold, and passageways providing a moderate restriction to the flow to the manifold of gas leaving the surfacesof the plates facingthe air outletregion.

4i-Ktreatingfcompartmentasiin claim-3 having' insert ithe'rewi'tn an apparatus ibrcenditioning a@ running continuous l'amentary" bundle comprisingac'ompartment, a positive feedingmeans, guides-v supported' at spaced'intervals' in the'- comnartmentfor guidingthe bundle along ak desired ag'a's'- recirc'ulatihg' device furthe" compartment, baflle'meansV within the compartmentfor directing the gas laterallyY through the' bundle', a afas'f humidifier in series with the recirculation device, anda variable speed device for discharging" the bundle from the apparatus' while subjecting the bundle to predetermined tension within the apparatus.

5. A treating compartment as in claim 3' having' in series therewith an apparatus for conditioning aA running continuous lamentary bundle comprisingv av compartment, a positive feeding means; means for introducing a gaseous conditioning medium into a region of the compartment near one wall ofl the compartment, means for withdrawing the gaseous medium fromI a region near an opposite wall, a continuous perforated supporting surface for theV bundle for facing the gas inlet region, a gas recirculation device for the compartment in series with a gas humidiiying means and a gas heating means, and a variable speed device for'disch'arging the bundle from the compartment while' subjecting it to a" desired tensien while in the compartment.

6L .AL-treating" compartment as in claim 3 having in series therewith an apparatus foi" conditioning a running continuous' filamenta'ry' bundle comprising a compartment, a' positive feeding means, means for introducing a gaseous conditioning ni'ediuni into a region' of the compartment' near one' wall;` means' foi" withdrawing the gaseous Vmedium from a region near an opposite wall,two

ppositely disposed sets of` r'olls, eacligset" being mountedI near one of thewalls', forleadingthe bundle progressively back. and forth over" rolls" of both sets in a zigzag path extending coextensively between the two' regions; perforated plates' supported within the' compartment between successive rolls along the zigzag path so that the surfaces of the plates' facing toward the gas inlet region-extend in' a' direction tangent to the peripherie's'of the rolls, avariable speed discharging means for the bundle for subjecting the bundle in' the compartment to a predetermined tension, a gas reci'rculating* device for the' compartment,

and" a gas humidifyin'g and heating"v means in Series with the recirculating device.

7.-.An` apparatus for conditioning a running continuous iilamentary' bundlecomprisingv aV compartment, ai positive feeding means, means for introducing a` gaseous conditioning medium into a region of the compartment near one wall, means for withdrawing the' gaseous medium from' a regionl near an opposite wall, two oppositely dis"- posed sets of rolls, each set b'eing mounted near one ofthe Walls, for leading the-bundle progres'- sively back and forth over rolls off both sets' in a` zigzag path extending coextensively between the two regions, perforated plates supported withinthe compartment between successive rolls along the zigzag path so that the surfaces of the plates facing toward the gas inlet region extend ina direction tangent to the p'eripheries of the rolls, a variable speedl meansY for'the bundle for subjecting` the bundle in the compartment to a predetermined tension, a gas recirculating device for' the compartment', a gas humidier in series with the recirculatingf device,l andl a heating meenammageenseneswnntuerecimunnging surfaces to laterally distend' and open theA iilamentary material thereof.

9. In a method of treating' a: running continu-'- ous' bundle of iilamentary material, the steps comprising drying the bundle to amoisture cbntent substantially below moisture equilibrium with the atmosphere, then passing the" bundle under tension over spaced supporting surfacesto spread the bundle laterally into` a flattened cross-sectional contour,. and subjecting` the bundle between said surfaces to' a transverse current of moisture-laden gas toward. a'- flattened surface of; and then througlnthe bundle to'laterally distend and open the lainentary' material and to raise the moisture content thereof to a desired level.

l0. In a method of treating a running continuous bundle of lamentary material, the steps comprising drying the bundle to a moisture content substantially below moisture equilibrium with the atmosphere. then passing thel bundle over spaced supporting surfaces to spread the bundle laterally into a iiattened crossesec'tional contour, and passing a current of moisture-laden air toward a flattened surface of., and then through, the bundle to laterally distend and open thelamentary material and to raise' the moisture content thereof to' substantial equilibrium with the atmosphere.

1l. In a method' of treating a running continuous bundle of 'filamentary material, the steps comprising drying the bundle to a moisture content substantially below moisture equilibrium with the atmosphere. then passing the bundle under tension over spaced supporting surfaces't'o spread the bundle laterally into a flattened crosssectional contour, passing a current of'm'oistureladen air toward a attened surface of,.and then through, the bundle to laterally distend and-.open the filament-ary material and to return themois'- ture content thereof to substantial equilibrium with thek atmosphere, and applying tension lonigitudinally to the bundle while' passing it. over said surfacesto stretch the lanientary material to a predetermined extent.

12. In a method of treating a runningcontinuous bundle of iilamentary material, the steps comprising drying the bundle to' a moisture'content substantially below moisture equilibrium with the atmosphere, passing the bundle under tension along a zig-zag path over surfaceswhich produce changesv of direction in the path, passing the bundle between opposing pairs of surfaces spaced alongv said path between the first-named surface, said' bundle being spread laterally into a attened cross-sectional contour by passing over said supporting surfaces, and passing moisture-laden air toward the flattened surfaces of, and then through, the bundle from one side ofthe zig-zag path to laterally distendV and open the lamentary material and to return the moisture content thereof to a desired level. l

WALLACE A. KNOPP.

(Retercnces on following page) REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Kerst et al. Sept. 23, 1924 10 Number 10 Name Date Schilde July 7, 1931 Karlson et al. Feb. 26, 1935 Hurxthal Mar. 26, 1935 Partsch Apr. 6, 1937 Mayes Jan. 19, 1943 Schwartz June 13, 1944 Mummery July 3, 1945 Walter et al Apr. 27, 1948 Millel` et a1 Dec. 14, 1948

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