US2843881A - Apparatus for opening crimped continuous filament tow - Google Patents

Description

July 22, 1958 w. T. BISHOP ET AL 2,843,381 APPAKRATUS FOR OPENING CRIMPED CONTINUOUS FILAMENT TOW Filed June 26, 1956 V 5 Sheets-Sheet 1 WILLIAM T. BISHOP LEE T. TICHENOR INVENTORS.

BY (QM (QM w W z w ATTORNEYS.

July 22, 1958 w, BISHOP ETAL 2,843,881

APPARATUS FOR OPENING CRIMPED CONTINUOUS FILAMENT TOW Filed June 26, 1956 s Sheets-Sheet 2 DRWEN RETARD ROLLS WILLIAM T. BISHOP ES??? LEE T. TICHENOR I BY ATTORNE Y5.

July'22, 1958 w. 1'. BISHOP ETAL 2,843,831

I APPARATUSFOR OPENING CRIMPED couwmuous FILAMENT TOW Filed June 26, 1956 s Shets-Sheet 3 AT'TO RN EYS.

APPARATUS FDR OPENING CRIMPED CONTINUOUS FILAMENT TOW William T. Bishop and Lee T. Tichenor, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New .lersey Application June 26, 1956, Serial No. 594,045

Claims. .(Cl.19--65) The present invention relates to a method and apparatus for opening crimped continuous filament tow. More particularly, the invention is concerned with an improvement in the apparatus disclosed and claimed in copending U. S. patent application Serial No. 416,010 filed March 15, 1954, by John W. Smith, now Patent No. 2,790,208, of April 30, 1957.

Textile tows made up of grouped, parallel, continuous, synthetically spun, crimped filaments, for example five hundred to five million in number, are prepared by bringing together in grouped, parallel relationship filaments spun from a plurality of spinerette holes, usually from a plurality of spinerettes. While the individual fibers or groups of fibers may be crimped before being combined, it is customary to first form the tow and then run it through a crimping device. These crimped tows may be used for some purposes in their continuous filament form, while for other purposes the tows are converted into masses of staple fiber. In either event, continuous filament tows generally are much more useful if they have an open structure characterized by spacing of large numbers of the filaments from their adjacent filaments and particularly by a uniformtransverse distribution ofthe filaments within the tow bundle. However, it is diflicult to provide a well opened tow due to the fact that ordinarily many of the tow filaments. tend to cling together as small groups visually identifiable by reason of a relatively high filament density. A method and means is disclosed in the aforesaid Smith application for opening these crimped tows as they move continuously in a longitudinal direction. In accordance with the Smith method, a .tow longitudinally moving is placed under a relatively high longitudinal tension so that the crimps in the filaments of the tow are substantially straightened out. This tension may be just short of that required to break the tow. .When the tension is released suddenly, the crimps return to the filaments and in so doing cause the filaments to elbowtheir neighboring filaments, moving the latter and/or themselves transversely. Inasmuch as more elbowing occurs where filament density is highest and relatively little elbowing occurs where filament density is low, a tow which has been opened in this manner has a more nearly uniform filament distribution. The tow also assumes a larger cross-sectional area as a result of the opening treatment, there being more spacing of adjacent filaments in general. t

The prior invention involves tensioning the tow by pulling on it longitudinally with a pair of driven rolls which form a bite for the tow and simultaneously, at a point spaced from the driven rolls upstream in the path of tow movement, retarding movement of the tow with a pair of drag rolls or equivalent retarding device. Tow discharged from the driven rolls is maintained in a relatively relaxed condition and under relatively little tension. This little amount of tension normally is substantially less than the tension afforded by cooperation of the driven rolls with the drag rolls. The relaxed condition of the tow is maintained by pulling it away from the tensioning device by a tow moving means such as an aspirator, or rolls driven at a proper speed to move the tow without putting substantially more tension on the tow than is required to remove the slack from it.

Opening or blooming of the tow is enhanced in accordance with the prior invention by applying a vibrational force to the tow while it is under high tension between a pulling point represented by the driven rolls and a retarding point represented by the drag rolls. The vibrational force is applied in a manner such that it serves: to rapidly and repeatedly suddenly apply and suddenly release an additional increment of tension over and above that produced by the pulling and retarding means. A specific means heretofore employed for vibrating the tensioned tow comprises a striker member operating at a high speed, of for instance 3500 strokes per minute, which strikes the tensioned tow transversely (between the pulling and retarding points) and deflects it, thereby suddenly elongating its path. and additionally stretching the tow, and alternately releasing the tow from the deflecting force.

We have found that it the force employed for vibrating the tow is applied more along the longitudinal axis of the tow rather than transversely .to it, a better opening of the tow results. in accordance with our invention, the vibrating apparatus provides two members for contact with the tow, these members being spaced apart on opposite sides of the normal tow path between a pulling mechanism and a retarding mechanism. The tow is drawn in a clockwise direction partially around one member of the vibrating apparatus, continues to the next member in a line sub stantially normal to the normal tow path (i. e. a straightline between the pulling and retarding points), and is drawn in a counter-clockwise direction partially around the next member. The members are caused to vibrate (oscillating or reciprocating) simultaneously but in opposite directions generally toward and away from the pulling mechanism and the retarding mechanism, whereby the tow is alternately tensioned and released. The effect of the apparatus is to alternately lengthen and shorten the path of the tow between the pulling mechanism and the retarding mechanism.

The invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of one embodiment of a vibrating device of the invention,

Fig. 2 is a side elevation of tensioning means. employing the vibrating device of Fig. 1, l

Fig. 3 is an end elevation, in part cut away, of the apparatus of Fig. 2,

Fig. 4 is a diagrammatic representation of the function of the device of Fig. 2 in opening tow,

Fig. 5 is a View of a modified striker bar,

Fig. 6 is a diagrammatic side elevation of a modified form of the device of Fig. 2, showing in addition means for moving .tow away from driven rolls under relatively low tension.

Fig. 7 is a diagrammatic side elevation of a tensioning device embodying still another form of vibrating means in accordance with the invention,

Figs. 8, 9 and 10 are views of various modifications of striker bar supporting assemblies.

Terms such as upper, lower, above, below, horizontal, and the like are used to describe apparatus illustrated in the drawings and disclosed herein. However, it will be understood that these terms are used in fact merely for convenience of description and are by no means critical, and that the same apparatus will be operative to perform its function whether in the described position or disposed vertically or obliquely, or turned on its side.

The tow opening device of Fig. 2 comprise a frame 1 carrying a pair of driven rolls 2 and 3 and a cooperating pair of drag rolls 4 and 5. All of these rolls have resilient surfaces formed by a rubber covering as illus trated, primarily to provide a more positive bite on the tow, and the rolls are properly spaced (or may beadjustably spaced) to assure an appropriate grip on tow passing therebetween. The driven rolls 2 and 3 are powered from motor 6 by means of chain 7 so that these turn in opposite directions to pull tow in the direction indicated by the arrows. These rolls constitute a pulling mechanism designed to place a positive pull on the tow 8 passing between them. In order to get sufiicient tension on the tow, the tow is retarded in its movement toward the driven rolls 2 and 3 by means of the drag rolls, although any other suitable tow retarding device known to the art may be used. The drag rolls 4 and 5, like the driven rolls, are spaced to provide a positive gripping bite on the tow 3 passing between them. The retarded rolls are positively turned under the infiuence of motor 6 acting through the reduction gear unit 9 and chain 10. The rolls 1 and therefore are driven at a speed which is lesser than that of the rolls 2 and 3 by an amount predetermined to result in an optimum amount of tension on the tow. Approximately midway between the two pairs of rolls and substantially on (or near) the plane passing through the bites of the two roll pairs is a vibrating mechanism having a pair of parallel, striker bars 11 and 12 providing tow c011- tacting points spaced apart and disposed respectively above and below the normal tow path represented by a horizontal plane passing through the bites of the two roll pairs. It will be seen that in passing through the tension 'zone comprising the ratch between the pulling point constituted by the bite of the driven rolls 2-3 and the retarding point constituted by the bite of the drag rolls 4--5, the towis threaded through the vibrating device in such a manner that it passes from the retarding point to, under, and in a clockwise direction partially around the lower tow contacting point, i. e. striker bar 12, thence to, over, and in a counterclockwise direction partially around the upper tow contacting point, i. e. striker bar 11. The striker bars are carried on supporting arms 13 and 14 which are fixed to sleeve 19 rigidly keyed to a shaft 15 journalled in the member 16 fixed to the frame 1. The normal, i. e. mid-position of the striker bars advantageously is that in which one is above the other, substantially in a plane normal to that passing through the bites of the two roll pairs and at a point substantially midway between the latter.

The vibrating device of the invention is more clearly illustrated in Fig. 1. The striker bars 11 and 12 are shown as supported at one end by arms 13 and 14, and additionally supported on their opposite ends by similar arms 17 and 18. Means is provided for vibrating the striker bars so that they move simultaneously to and fro respectively, the upper bar 11 moving to the left in Fig. 1 as the lower bar 12 moves to the right and vice versa. The vibratingmeans comprises a motor 20, driving a shaft 21 on which an eccentric 22 plate, rotating with the shaft and providing a peripheral cam surface. Cooperating with this camv surface is a cam follower wheel 23 mounted for rotation on an arm 24 keyed to the shaft 15. It will be obvious that as the motor 20 is energized and the shaft 21 rotates, the resulting camming action causes oscillation of the vibrator shaft 15 and vibrating motion of the striker bars 11 and 12 alternately toward and away from the tow pulling point (and tow retarding point).

In order to obtain the desired opening of any given tow, the rate of vibration, the length of the stroke of the striker bars, the speed of movement of tow through the tensioning device, and the amount of tension applied by the roll pairs, each may be varied. In treating a tow of, for example, 15. to 25 thousand filaments of cellulose acetate of e. g. 3 to 18 denier per filament and a total denier of, e. g. 60,000 to 120,000 containing about 4 to 15 crimps per inch, striker bars may be employed which are oscillated about /2 inch to 1 /2 inches on an arc of a 6 /2 inch diameter circle. This is an oscillation of about 17 degrees but where suitable it could be increased to, for example, as much as about 65 degrees. A suitable frequency, generally within a range of about 600 to 2,700 cycles per minute is employed. The tow tension is selected on the basis of variables such as the speed of the tow, number of crimps per inch, denier per filament, total denier, composition of the filaments, and the particular cross-sectional character of the individual filaments. Tows have been successfully processed at tensions of from 0.025 gram per denier to as much as one gram per denier. The striker bars suitably may have diameters of, for example, 0.75 to 1.5 inches.

Referring again to Fig. 2, the illustrated position of the striker bars may be used as the mid-position in their paths of oscillation. The path of tow through the apparatus then would be of mean length in the indicated position. It will be observed that as the motion of the striker bars is in a clockwise direction, the length of the tow path in the ratch between the two pairs of rolls is increased. However, since the tow is firmly gripped by each of the roll pairs, the increase in length of path results in stretching of the portion of tow which is at that instant in the ratch. On the return stroke of the striker bars in a counter-clockwise direction, the tow path is shortened and the additional increment of tension which resulted from the clockwise movement of the striker bars is suddenly released. Furthermore, it will be observed that the tensioning or stretching produced by the striker bars 11 and 12 is largely longitudinally of the tow.

With reference to Fig. 3, which is an end elevation of the apparatus of Fig. 2 from the left side of the latter, the means by which the rolls and vibrator are mounted and driven is more clearly shown. The apparatus is partly cut away to show the drag rolls 4 and 5 in elevation. These are mounted on shafts 39 and 40. The motor 6 mounted on the frame 1 drives shafts 28 and 29 of the rolls 2 and 3 (not shown) respectively by means of the chain 7. A belt 30 provides the drive for the reduction gear unit which powers the rolls 4 and 5.

With reference to Fig. 4, the function of the apparatus will be better understood. The tow is represented at 31 as approaching the tensioning device from a supply source, the tow containing its high degree of sharp crimp, the crimp being gathered and grouped more or less completely in phase. The tensioned tow between the pulling and retarding points is illustrated at 8 as it is being pulled under the influence of driven rolls 2 and 3 and, while being retarded by the drag rolls 4 and 5, is subjected in the ratch between the two pairs of rolls to a relatively high degree of tension afforded by the cooperation of the rolls. An additional increment of rapidly and repeatedly suddenly imparted and suddenly released tension is applied as a result of vibration of the pair of striker bars 11 and 12. In Fig. 4 the path of striker bar vibration is indicated by the full line representation of the striker bars and their supporting arms in the extreme counter-clockwise position and the dotted line representation of their extreme clockwise position. At 32 is illust-rated the more or less slack condition of the tow as discharged by the driven rolls 2 and 3 into a zone of relative relaxation through which the tow is moved under relatively little tension substantially less than the rela tively high tension in the ratch of the tensioning device. The slack tow is shown in its opened and bloomed condition. The opened and bloomed tow has a softer and somewhat less pronounced crimp, largely out of phase. The entire tow has a much larger cross-sectional area than at 31 and the filaments of the tow have a more uniform cross-sectional distribution.

In Fig. 6 a means for moving the bloomed tow under relatively low tension away from the driven rolls 2 and 3 is illustrated as a pair of delivery rolls 25 and 26 which provide a bite for tow passing therebetween and which are driven at a slower rate than the rolls 2 and 3, for example, at a rate which is the same as that of the rotation of drag rolls 4 and 5, in which case the delivery rolls 25 and 26 may be powered from a common transmission with the rolls 4 and 5. However, as illustrated in Fig. 6, the drag rolls, instead of being positively driven, are illustrated as being idler rolls turned only by reason of the movement of tow passing between them as it is pulled by the driven rolls. In this case the drag rolls may be, if desired, equipped with any suitable braking means known to the art for applying a predetermined drag and thus a predetermined amount of tension to the tow. However, as illustrated these rolls are so spaced that the force necessary to overcome the friction in flexing the rubber surfaces provides the requisite braking action. The relatively low tension on the tow between the delivery rolls and the driven rolls may be suflicient only for the mere removal of slack from the tow as indicated at 32.

The embodiment diagrammatically represented by Fig. 6 is an arrangement in which the bites of the roll pairs are staggered, i. e. vertically offset from each other in such a way as to allow the striking bars of the vibrating mechanism to more nearly exert a longitudinal pull on the tow. If desired, the illustrated position of the striker bars may be established as the extreme clockwise position whereby the greatest tension is not applied by the vibrator until the pull is almost completely longitudinal.

The delivery rolls 25 and 26 are carried by shafts 45 and 46, respectively, which are rotated in opposite directions under the influence of reduction gear unit 43, in turn powered by motor 42. The motor also provides a direct drive for driven rolls 2 and 3.

The striking bars advantageously are prepared from stainless steel having a high polish, but may be formed of any other suitable material providing low friction characteristics. The bars may for instance be prepared from stainless steel tubing. Under certain conditions, however, the loose or broken ends or filaments in the tow may exhibit a tendency to wind themselves around a member of circular section.

In accordance with Fig. 5, therefore, the striker bars are formed as indicated from sheet metal to provide a curved portion and a webbed extension 41 which will successfully prevent the winding on of any broken or loose ends or filaments.

Fig. 7 diagrammatically represents another embodiment of the invention in which the striker bars, in moving alternately toward and away from the driven rolls follow a path of vibration which is a straight line rather than an arc. reciprocates in a single plane. Such an arrangement may be provided by means of a pair of spaced chains disposed on either side of the tow path with the striker bars being :arried by and at their ends fixed to the two chains. Thus the striker bars bridge the space between the pairs of :hains and in so doing cut across the tow path. The elevation of Fig. 7 shows one chain 37 carried around two sets of sprocket wheels 35 and 36, the sprockets forming between them two flights, i. e. upper and lower flights of the supporting chain 37. One end of the striker bar 11 is carried on the upper flight and one end of the striker bar 12 is carried on the lower flight of the :hain 37. Means (not shown) is provided for vibrating the chain as indicated by arrows.

Various modifications of the oscillating form of striker bar supporting means of Fig. 1 may be employed for structural reasons or to obtain advantages in the easy threading of the tow through the vibrating device. In each of Figs. 8, 9 and 10 the oscillating shaft is shown as carrying striker bars 11 and 12 supported through In other words, each striker bar in this case various arrangements obtained by omitting certain of the supporting arms 13, 14, 17 and 18. In the structure of Figs. 9 and 10 the shaft 15 does not extend across the tow path but terminates short of it. In the embodiment of Fig. 10, an arm 44 provides the only support for the striker bar 12.

From the foregoing description and following claims it will be obvious that the invention is not limited to the specific means described herein but extends to a number of equivalent means which will be satisfactory for providing in the tow path between a tow pulling point and a tow retarding point a pair of spaced, parallel striker bars which vibrate simultaneously in opposite directions toward and away from the pulling point and the retarding point, whereby the tow periodically is given 2. suddenly applied and suddenly released longitudinal stretch in addition to the stretch continuously applied by the cooperation of the mechanisms at the pulling and retarding points.

Reference is made to Crawford and Stevens U. S. patent application Serial No. 374,168, filed August 14, 1953, now Patent No. 2,794,480 of June 4, 1957, for further disclosure of a tow opening apparatus comprising cooperating drag rolls, driven rolls, and delivery rolls.

We claim:

1. In a device for opening continuous multi-filament crimped tow, in combination, a first pair of rubber covered rolls, a second pair of rubber covered rolls, said pairs of rolls being adjustably positioned to form nips between the rolls of each pair and positioned to form a ratch between the pairs of rolls, means including said pairs of rolls for conducting said tow between said pairs of rolls and through said ratch, driving means for driving said pairs of rolls, means associated with said driving means for driving said first pair of rolls at a rate less than said second pair of rolls, whereby a tension is exerted on the tow in said ratch sufficient to straighten out the crimps, and a rockable device positioned adjacent the tow in said ratch adapted to contact said tow and periodically to increase the tension on the tow while it is passing through said ratch.

2. In a device for opening continuous multi-filament crimped tow, in combination, a first pair of rubber covered rolls, a second pair of rubber covered rolls, said pairs of rolls being adjustably positioned to form nips between the rolls of each pair and positioned to form a ratch between the pairs of rolls, means including said pairs of rolls for conducting said tow between said pairs of rolls and through said ratch, driving means for driving said pairs of rolls, means associated with said driving means for driving said first pair of rolls at a rate less than said second pair of rolls, whereby a tension is exerted on the tow in said ratch sufficient to straighten out the crimps, and a rockable device having a pair of spaced members positioned adjacent the tow in said ratch adapted to contact said tow and periodically to increase and decrease the tension on the tow While it is passing through said ratch.

3. In a device for opening continuous multi-filament crimped tow, in combination, a first pair of rubber covered rolls, a second pair of rubber covered rolls, said pairs of rolls being adjustably positioned to form nips between the rolls of each pair and positioned to form a ratch between the pairs of rolls, means including said pairs of rolls for conducting said tow between said pairs of rolls and through said ratch, driving means for driving said pairs of rolls, means associated with said driving means for driving said first pair of rolls at a rate less than said second pair of rolls, whereby a tension is exerted on the tow in said ratch sufiicient to straighten out the crimps, and a rockable device having a pair of spaced apart rods positioned transversely of the tow in said ratch adapted to contact said tow and periodically to increase and decrease the tension on the tow while it is passing through said ratch.

4911i a device-for=opening continuous multi-filament' crimpedtow, in' combination, a first pair of'rubber covered rolls," a second pair of rubber covered rolls, said pairsof rolls being adjustably' positioned to form nips between -'the' rolls ofeach pairand positioned to-form a ratch between the pairs of rolls, means including said pairsof' rolls for-conducting saidtow between said pairs of rollsand through said ratch, driving means for driving said pairs of rolls, -means associated with said driving means for drivingsaid first pair of rolls at a rate less than said second pair 'of rolls,- whereby a tension is exerted on-th'etow-in said ratch sufficient to straighten out the crimps, a rockable device having a pair of spaced apart rods positioned adjacent-the'tow in said ratch adapted to tween the pairs of rolls, means includingsaid pairs of rolls for conducting =said tow between said-pairs of rolls andthrough said-ratch, a motor-and chain drive adapted to-drive said second pair of rolls, a gear-reduction-unitconnected-to saidmotor=and to said first pair-of rolls adapted to drive said first pair of rolls at a rate less than said second pair-of'rolls, a rockable device-having a pair of spaced apart rods positioned. adjacent-the-tow in said ratch adaptedto contact the opposite sides of said tow and periodically to increase and decrease the-tension on the tow whileit-is passing through'said'rateh,

and means for actuating the rockable device at high -fre-- quency.

References Cited in the file of this patent- UNITED: STATES PATENTS 1,764,892 Rocamora" June 17', 1930 2,064,279 Tayloretal. Dec. 15,'1936"i 2,215,112 Van Beek et a1 Sept. 17, 1940 2,771,635 Munch Nov."27, 1956' FOREIGN PATENTS 710,708 Great Britain June 16, 1954

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