US2790208A - Method and means for opening crimped continuous filament tow - Google Patents

Description

Apnl 30, 1957 J. w. SMITH 2,790,208

METHOD AND MEANS FOR OPENING CRIMPED CONTINUOUS FILAMENT TOW Filed March 15. 1954 RA TCH F lg.

DR/ EN RETARDED mvs/o/v ROI-L5 ROLLS JOH/V WINS TON SM/TH IN VEN TOR.

ATTORNEYS METHOD AND BEANS FOR OPENING CRIMPED CONTINUOUS FILAMENT TOW Eohn Winston Smith, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March 15, 1954, Serial No. 416,010

3 Claims. (Cl. 19-66) The present invention relates to an improved method and means for opening crimped continuous filament tow to increase the cross-sectional area of the tow and the uniformity of fiber distribution therein and to remove shiners, married fibers and concentrated bundles of filamerits within the tow.

in the handling and treatment of tow, difificulties are experienced due to the fact that generally the filaments are disposed in small bundles. That is to say rather than being uniformly distributed across the tow the filaments are accumulated into bundles easily identificable as such within the tow itself. Also, many of the filaments tend to adhere to adjacent filaments causing a condition variously termed shiners and married fibers, which result in tangles during further processing of the tow. To facilitate the working of the fibrous material in the tow, either before or after it has been converted into staple fiber, it is'desirable to remove shiners, that is, to separate adhering fibers, in order to increase the openness of the tow and of staple formed therefrom. It is also often sought to increase the openness or bulk of the tow by disintegration of smaller groups or bundles of filaments therein with simultaneous enlargement of the cross-sectional area of the tow. That is to say, it is often desired to achieve enlargement of tow diameter and increase in uniformity of fiber distribution in the tow.

A method and apparatus providing for continuous opening or" a longitudinally moving crimped continuous filament tow is disclosed in Wallace '1'. Jackson U. S. patent application Serial No. 403,131 filed January 11, 1954 to which reference is hereby made. This method takes advantage of the inherent springiness of the crimped tow and its ability, when stretched into a condition in which the crimps are substantially straightened out, to retract or spring back to its original length, and the invention is specific to tow having this characteristic in the absence of any substantial tendency toward permanent elongation or breaking of the filaments themselves when under the amount of tension required to substantially straighten out the crimps.

it is possible, using the means disclosed by Jackson, to open a tow in a continuous manner, increasing the bulk and uniformity of fiber distribution and removing adhered shiners and married fibers from the tow. This operation sometimes is referred to as blooming and results in a condition making the tow more suitable for subsequent processing, whether in tow or staple form, in various types of converters, drafters, and the like. In particular, the means is eifective in conditioning of tow for conversion into tobacco smoke filter elements. According to the Jackson procedure, a longitudinally moving tow of crimped continuous filaments is subjected to a continuous longitudinal tension at one zone in the path of its movement and the tension is suddenly released in an immediately adjacent zone downstream of the :tension zone. in a most advantageous embodiment of that method, an apparatus for continuously opening :a crimped continuous filament tow comprises two cooperating pairs 2,790,208 Patented Apr. 30, p 11957 of rolls positioned to form a path for longitudinally moving tow, one pair of the rolls being downstream of the other, the downstream rolls being positively driven tension rolls for exerting a pulling force on the tow, and the upstream rolls being retarded rolls adapted to exert a holding back effect on the tow against the pulling force on the tension rolls. Upon discharge of the tensioned tow from the bite on the tension rolls into azone of relaxation, i. e. relatively little tension, the tow blooms under the influence of the lateral forces exerted by each fiber in returning to its normally crimped condition.

I have discovered that an improved opening effect may be obtained in the procedure described above if, while the tow is under tension in a tension Zone between driven tension rolls and retarded rolls, the thus tensioned tow is subjected to a periodically applied suddenly impartedand suddenly released additional increment of tension. In accordance with the most advantageous embodiment of the invention, I have found that if a striker and anvil arrangement be placed along the path of the tow in the tension zone of the prior apparatus and the striker-reciprocated rapidly to impart the additional increment of tension to the tow, e. g. enough to impart approximately 8% additional stretch, the opening efl'ect is improved and multiplied to a substantial degree.

7 The invention is illustrated in the accompanying drawings in which Fig. 1 is a diagrammatic representation of the functioning and arrangement of means in accordance with the invention,

Fig. 2 is a side elevation of a preferred apparatus embodiment, and

Fig. 3 is an end elevation, apparatus shown in Fig. 2.

In the representation of Fig. l, a continuous length of continuous filament tow 10 is shown passing from right to left in the direction of the straight horizontal arrows. The tow is moved under the influence of a pair of cooperating driven tension rolls 11 and 12 and is retarded in its movement by means of a pair of cooperating retarded rolls 13 and 14 so that in the ratch, i. e. the tension zone between the bites of the two roll pairs, there is sufficient tension to substantially remove the crimp therefrom. The reference numeral 15 designates the tow in its tensioned condition. The tension to which the tow normally is subjected as it moves through the tension zone along the path defined by the spaced pairs of rolls normally is of an order of 1050 pounds, sufiicient to cause the tow to spring out and expand to a condition as at 16 when it is discharged from the bite of the driven rolls into a zone of relaxation, i. e. relatively little or no tension. This opening or blooming is the result of inherent forces in the filaments of the tow. Upon emergence from the tension zone into the zone of relative relaxation, each filament in the tow retracts or springs back to its original length and crimped condition and in so doing exerts a force radial to the axis of its path. With each filament acting in concert with closely adjacent and contiguous filaments, the lateral force efifect produced by the springing back is emphasized and exaggerated into the accumulated effect of the forces exerted by all the filaments acting upon the surrounding filaments and is what might aptly be described as an explosive blooming action.

In accordance with the instant invention, while the tow is under the first amount of tension provided by the two pairs of rolls, an additional increment of tension is intermittently applied to it in-rapid cycles of sudden application and sudden release. This is accomplishedwith a-reciprocating mechanism 17 positioned along the tow path between the driven and retarded rolls and having a reciprocating-rod 18 carrying at its end a striker 19. "The in part cut away, of the greases vertically disposed arrows in Fig. 1 illustrate the reciprocating motion of the striker 19 under the impulse from reciprocating mechanism 17. The striker moves against and contacts the tow normal to the tow movement path. In its uppermost position, the striker does not contact the tow, but in the downward stroke contact is made and in the lowermost position of the striker 19 the tow is deflected from its normal path through the tension zone. Most advantageously the amount of deflection caused by the striker is sufficient to impart an additional stretch of the order of approximately 8% to the tow. In order to accomplish this more easily, stationary anvils 20 and 21 are positioned along the tow path on the opposite side thereof from the reciprocating mechanism. The spacing of the anvils relative to each other and to the rolls is not critical. The purpose of the anvils being merely to reduce the amount of total deflection, i. e. striker stroke length necessary to impart the desired additional increment of tension to the tow. Preferably the anvils are positioned so that they themselves do not deflect the tow path. It is preferred also that they be so disposed that the striker path will be midway between them whereby to avoid side thrust on the striker.

I have found it advantageous in working with a crimped cellulose acetate tow to reciprocate the striker approximately 3 inches per stroke with about 3,500 strokes per minute. The rate of receprocation, like the stroke length, is quite variable and normally will be satisfactory if maintained in the range of 1,800 S. P. M. to 5200 S. P. M., S. P. M. meaning downward strokes per minute. An essential requirement seems to be that the strokes be made rapidly enough to set up a condition which may be termed a vibrational effect. As another criteria it may be said that with the tow moving through the device at a rate of the order of about 10 to 1700 feet per minute, the strokes of the striker should be of a high enough order so that not more than about 50 crimps pass under the striker between strokes. Preferably, far fewer, e. g. not more than about 5 crimps should pass under the striker between strokes.

An apparatus embodying the invention is illustrated in Fig. 2 wherein is shown a frame 22 supporting a pair of driven rolls 23 and 24. This pair together with a pair of retarded rolls and 26 form a path for tow passing between the bites thereof. The two pairs also serve to provide therebetween a tow tensioning zone. The rolls are all provided with elastic surfaces whereby,

with close spacing of the rolls of each pair, a positive grip on the tow is obtained and slippage of the tow through the bite of the rolls is reduced to a minimum.

The rolls 23 and 24 are positively driven in the direction indicated by arrows thereon by means of a motor 28, and the rolls 25 and 26 are driven at a slower speed through a variable speed transmission 29.

A means for intermittently applying an additional increment of tension by sudden application and release in rapid cycles comprises pneumatic reciprocator 30 and a striker element 31 carried by a reciprocating rod thereof. The striker 31 is driven to make approximately 3,500 strokes per minute across the tow path into a region between two spaced anvils 32 and 33 having smooth rounded working faces 34 and 35 respectively lying in a plane parallel to and adjacent the tow path. The working faces of the anvils, as well as the bottom of the striker, should be rounded and sufficiently smooth and polished to avoid cutting the filaments. Equally important is the requirement that these surfaces not substantially impede the movement of tow across them. In other words, there should be enough slippage and sliding that forces applied to tow between the anvils will be felt for the full length of the tow in the tension zone.

With reference to Fig. 3 it will be seen that the striker 31 is of a width necessary to provide ample bearing surface for the tow and that when the striker is in a position above the tow path there is ample clearance for passage of the tow along its normal route between the bites of the two roll pairs.

The invention is operative with crimped continuous filament tows in general so long as the filaments of the tow meet the general requirements of sufficient strength to prevent breakage and an absence of permanent elongation under the tension necessary to achieve the purpose of the invention. It is obvious that the filaments must have an inherent urgency to return to their normal length and crirnped condition when tension is removed. The invention is useful with crimped tows of cellulose acetate, saponified cellulose acetate, and regenerated cellulose, and crimpecl tows of acrylic, polyester, polyamide and protein type filaments. Tows varying in size from 500 to 5,000,000 filaments of 1.0 to 50 or more denier per filament may be opened by means of the invention. The operating range of crimp will vary with the type fiber and its denier per filament. For instance, with a cellulose acetate tow of 2 D./F. the crimp would be in the order of 12 to 14 crimps per inch; for 10 D./F. to 8 crimps per inch; and for 50 D./F., 3 to 4 crimps per inch.

While the illustrated retarded rolls are positively driven, e. g. at preferably 99.5% of the speed of the tension rolls, they may be retarded merely by a frictional braking effect such as results from such close spacing of the retarded rolls that substantial work must be done to overcome the friction in flexing of the elastic roll surfaces. The invention is illustrated in the following example.

Example 1 A tow of 5 denier per filament and 100,000 total denier was formed with the products from a number of spinning cabinets. The tow was lubricated with a special pharmaceutical grade of mineral oil. A crimp of 7.0 crimps per inch was applied to the tow which was then dried and sent to a ball warping machine where it was wound on a fiber tube. The ball warp package thus prepared was used as a supply to a cigarette filter machine such as disclosed in Crawford and Stevens U. S. application S. N. 374,168 filed August 14, 1953. Upon being removed from the ball warp the towwas immediately run through an opening device embodying the instant invention and the filter plugs resulting from the cellulose acetate filaments so processed were found to be greatly improved in regard to fiber distribution and absence of channeling of the smoke as Well as in the respect that the filters were firm and resilient.

The basic concept of this invention may be adapted for use with a wide variety of filamentary materials under varying conditions. Thus, the apparatus of the invention may find a number of different and varying embodiments. For example, the means for applying an additional increment of tension may be used satisfactorily in combination with a tension roll device wherein the retarded rolls are dispensed with and their function is supplied solely by means of a tow source, e. g., a ball warp, which is friction-- ally braked or unwound through a power drive at a speed sufficiently less than, c. g. 99.5% of that of the draw of the power driven tension rolls.

Furthermore, while the striker and anvil arrangement has been described in terms of vertical reciprocation, uppermost and lowermost positions and downward stroke, horizontal alignment of the striker and anvil arrangement proves equally satisfactory, as does also an arrangement providing for upward tensioning strokes by the striker.

I claim:

1. Means 'for opening a crimped continuous filament tow comprising a pair of spaced means forming a path for moving tow therebetween, the means including a front means adapted to continuously pull tow along the path under tension and a back means adapted to continuously exert a holding force on the tow while allowing the tow to pass due to a greater force exerted by the front means, a first anvil positioned between the front and back means and providing a working face immediately adjacent to the tow path, a second anvil positioned between the first anvil and the front means, spaced from the first anvil and providing a working face immediately adjacent to the tow path, a reciprocating striker positioned for operation on the opposite side of the tow path from the anvils and disposed to operate in a plane between the anvils normal to the tow path and to the plane of the working faces of the anvils, and means for rapidly reciprocating the striker to supply an additional increment of tension to the tow in suddenly applied and suddenly released cycles, the reciprocating striker being adapted in one extreme position to deflect the tow path by carrying it into a position between the anvils and in the other extreme position to stand free of the tow path on the side opposite the anvils.

2. Method for opening crimped continuous filament tow comprising applying a first amount of tension to the tow sufiicient to substantially straighten out the crimps therein, while the tow is thus tensioned periodically applying a suddenly imparted and suddenly released additional increment of tension, and thereafter suddenly releasing the tow from the first amount of tension.

3. Method as defined in claim 2 wherein the tow is continuously moved in a longitudinal direction along a fixed path and the tension is applied in a fixed tension zone forming a part of the path.

4. Method as defined in claim 3 wherein the additional increment of tension is of an order which will result in about an 8% additional stretch in the tow.

5. Method for opening crimped continuous filament tow comprising longitudinally moving the tow successively through spaced pairs of gripping rolls defining a tension zone therebetween, intermittently additionally stretching the tow while it is under tension in the tensioning zone, and suddenly discharging the tensioned tow from the tensioning zone into a zone of relative relaxation.

6. An improved method for continuously opening a running length of crimped continuous filament tow, said method including the steps of (1) applying a constant predetermined longitudinal tension to the moving tow in a zone between a first pair of fixed points in the path of the tow, the predetermined tension being sufiicient to temporarily remove some but not all of the crimp from the tow, (2) while the tow is under said tension intermittently applying an additional amount of tension to the tensioned moving tow between a second pair of fixed points in the path of tow between the first pair of fixed points, the rate of application of the intermittently ap- 5o plied additional tension being such that it is applied along the tow at least once in every 10 crimp lengths of tow, and (3) finally discontinuing the application of the intermittently applied tension and at the same time suddenly removing substantially all of said constant predetermined tension.

7. Method for opening crimped continuous filament tow comprising moving the tow longitudinally through a tension zone between a pair of retarded rolls and a pair of driven tension rolls spaced downstream from the retarded rolls, while the tow is in the tension Zone applying to it a first amount of tension necessary to substantially straighten out the crimps in the tow, simultaneously subjecting the tow to an intermittent suddenly applied and released additional tension, and maintaining the tension on tow discharged from the driven tension rolls at a value substantially less than the first amount of tension to which the tow is subjected in the tension Zone.

8. Improved tow opening apparatus comprising a cooperating pair of positively driven tensioning rolls providing a bite for tow passed therebetween, a cooperating pair of frictionally braked idler rolls providing a bite for tow passed therebetween, the braked rolls being spaced from the tensioning rolls and arranged in cooperation with the tensioning rolls to form a path for longitudinal movement of continuous filament tow into and through the bite of the braked rolls, thence into and through the bite of the tensioning rolls, means for removing at a relatively reduced tension tow discharged from the bite of the tensioning rolls, and a reciprocating striking means positioned adjacent the tow path between the braked rolls and the tensioning rolls, the striking means being adapted to strike tow in a direction normal to its movement at regulated intermittent intervals and to thus suddenly stretch and suddenly release the tow in accordance with reciprocating movement of the striker, said braked rolls having elastic surface portions and being positioned sufiiciently close to each other that the elastic surface portion of each is deformed by the force exerted against it by the opposed cooperating roll, whereby work done in flexing the roll surface portions as the rolls turn pro vides a braking force on the rolls.

References Cited in the file of this patent UNITED STATES PATENTS 2,004,139 Taylor June 11, 1935 2,278,888 Lewis -n Apr. 7, 1942 2,646,277 Southwick July 21, 1953 FOREIGN PATENTS 458,687 Canada Aug. 2, 1949

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