US2413969A - Apparatus for converting tow to top - Google Patents

Description

Jan. 7, v. R. APPARATUS on couvzmme raw TO TOP Filed y 194:5

Patented Jan. 7, 1947 APPARATUS FOR coma'rmd; I

'row TO TOP Vernal R. Hardy; Wilmington, DeL, assignor to E. 1. du Pont de Nemours 8; Company, Wilmington, Del.,' a corporation of Delaware Application July 31, 1943, Serial No. 496,848

5. Claims. (01. 19-1) This invention relates to a process and apparatus for drawing and breaking a tow oi continu ous filaments to form a top. More particularly. the invention relates to the conversion of a tow of cold-drawable continuous filaments, such as a tow of nylon filaments, into a spinnable top without destroying the continuity of the tow and slitributed so that there is substantial overlapping of ends if yarn of acceptable physical properties is to be produced. Up to the present; no satisfactory arrangement has been advanced to efiect suitable overlapping or staggered relationship of fiber ends in a stretch-breaking system. Furthermore, in the conversion of tow to top by the breaking method, the fibers produced may be varied in length and in physical characteristics by varyin the reach, i. e. the distance between the bites of the retaining and drawing rolls, and the relative peripheral speeds of the retaining and drawing rolls. However, for any setting or adjustment of the drafting frame now in existence, there are certain limitations in range of fiber lengths and varying physical characteristics that cannot be exceeded.

Nylon and other cold-drawable fibers have varying afilnity for dyestufis, depending upon the degree to which the fiber have been drawn. (See Lewis U. S. Patent No. 2,278,888.) For certain purposes this is considered desirable. In the case of a spun yarn prepared from fibers having different dye characteristics, a pleasing variegated colored appearance or better color depth is obtained.

An object of this invention is to provide an improved and novel method of converting continu-v ous filament tow to top with better fiber distribution. A further object of this invention is to provide a method of variously drawing cold-drawable filamentous material and breaking the same to produce staple-length fibers, each of which has non-uniform characteristics. Another object of this invention is to provide a novel arrangement of drafting rolls to enable this new process to be carried out. Other objects of the invention will be apparent from the description that follows.

The objects of this invention are, in general, accomplished by subj ecting the yarn to a stretchbreak system wherein the drawing rolls are of such construction or are so positioned relative to the retaining rolls as to simultaneously apply varying amounts of stretch to the continuous filaments at difierent positions transversely in the tow between the retaining and drawing rolls prior to breaking said filaments.

In order to more fully explain the invention. reference will be made to the accompanying drawing forming a part of this specification and wherein:

Figure 1 is a side elevation of a drawing frame illustrating the arrangement of the retaining and drawing rolls;

Figure 2 is a plan view of the retaining and drawing rolls shown in Figure 1;

Figure 3 is a side elevation showing a modified arrangement of the retaining and drawing rolls;

Figure 4 is a plan view of the retaining and drawing rolls shown in Figure 3;

Figure 5 is a side elevation showing a still further modified form of arrangement of the retainingand drawing rolls;

Figure 6 is a plan view of the retaining and drawing rolls shown in Figure 5;

Figure 7 is a side elevation of still another modified arrangement of the retaining and drawing rolls;

Figure 8 is a plan view of the retaining and drawing rolls shown in Figure 7;

Figure 9 is an enlarged plan view of one form of fiber which is produced; and

Figure 10 is an enlarged modified form of fiber.

Referring now to the drawing wherein like reference numerals designate like parts, the reference numeral 2 designates a plurality of ends of tow supplied from any suitable source (not shown) and which pass through a converging guide 4 in their passage to the stretch-break system. The stretch-break system, as shown in Figures 1 and 2, comprises a drawing frame in which the retaining rolls comprise, in the form shown in Figure 2, a driven roll 8 and a heavy or weighted floating roll 8 cooperating therewith, and the drawing rolls comprise a driven roll I0 and a heavy or weighted floating roll l2 cooperating therewith. The rolls 6 and III are driven in the usual manner (not shown) so that the peripheral speed of the drawing rolls l0 and I 2 is higher than the peripheral speed of the retaining rolls 6 and 8, whereby the desired stretching, breaking and drafting may be obtained.

As is shown in the embodiment illustrated in Figures 1 and 2, the retaining rolls 8 and 8 are mounted at right angles to the direction of travel of the tow, while the drawing rolls HI and I! are mounted in angular relation thereto so that the distance between the bite of the two sets of rolls on one end may be as much as several times the difference between the bite of the two sets of rolls at the converging end. In other words, the reach between the retaining and drawing rolls varies in length from end to end. In view of the difference in the reach from one side of the web of filaments to the other, varying amounts of stretch are applied and some of the filaments will be broken, with a relatively short part of the filaments being undrawn while other filaments will have longer undrawn portions or partially undrawn portions passed through the rolls before they are actually broken. The sliver resulting from the breaking operation is also drafted by the rolls to produce a top.

From the drawing rolls l8 and I2, the top passes through a condenser or trumpet ll, either of the stationar or rotary type, wherein the top is laterally compressed or condensed, particularly to remove the feather edge obtained in the preceding drafting operation. The laterally compressed top, after leaving the trumpet, passes between a driven roll l6 and a pressure roll I8 constituting condensing or compacting rolls which condense and compact the top passing therethrough. The condensing rolls l8 and I8 also serve to deliver the top to a suitable collection device.

Instead of having the retaining rolls at right angles to the direction of travel of the tow therebetween, such retaining rolls may b positioned at an angle to the path of travel of the tow passing therebetween, and the drawing rolls may be positioned at right angles or at an angle to the direction of travel-of the tow. The latter arrangement is shown in Figures 3 and 4 wherein the retaining rolls comprise a driven roll 38 and a heavy or weighted roll 32, said retaining rolls bein positioned in angular relationship relative to the tow passing therebetween. In this embodiment, as shown in Figures 3 and 4, the drawing rolls, which comprise a driven roll 34 and a heavy, weighted or floating roll 36, are also positioned in angular relationship with respect to the path of travel of the material passing therebetween. As shown in Figures 3 and 4, the bite between the retaining and drawing rolls gradually decreases from position to position in the direction of the converging ends.

In place of having one set of drawing rolls, two sets of drawing rolls may be utilized. In such an embodiment, which is shown in Figures 5 and 6, the retaining rolls, which comprise a driven roll 40 and a weighted or heavy floating roll 42, are positioned at right angles to the path of the tow passing therebetween. As previously mentioned, there are two sets of drawing rolls, each set containing a driven roll 44 and a heavy, weighted or floating roll 36. The two sets of drawing rolls are mounted so that the minimum and maximum reach between the retaining roll and each of the drawing rolls are substantially the same. In order to direct the web of filaments into two substantially equal portions and divert it through the respective set of drawing rolls, there is provided a stationary member 48.

In place of using cylindrical rolls, the drawing rolls may be made irusto-conical. Such an arrangement is shown in Figures 7 and 8, wherein the retaining rolls comprise a driven roll 58 and a heavy, weighted or floating roll 52, and the drawing rolls comprise a frusto-conical driven roll 54 and a heavy, weighted or floating frustoconical roll 58. The axis of rotation of the rolls 54 and 56 may be only slightly canted with respect to the axis of rotation of the retaining rolls or may even be parallel thereto. By this arrangement, not only is the reach different for the many different filaments constituting the tow, but the peripheral speed of the fiber-contact surface on the drawing rolls is made variable (depending on the taper of the roll) and thus greatly alters the amount and distribution of the stretch to the filaments. In this embodiment, it Will'be necessary to have the filaments subjected to a mini mum draft sufiiciently great to insure breakage.

In each of the preceding embodiments, by varying the relative speeds of rotation of the retaining and drawing rolls or by intermittently stopping the retaining rolls, the non-uniformities of fiber lengths and denier may be further accentuated. If desired, the tow may be comprised of filaments of varying denier or a number of tows, two or more of which have different deniers, and may be fed into this drawing frame to produce a great variety of fiber deniers in the sliver or top and in the spun yarn produced therefrom. When the filaments comprising the tow are of nylon or other cold-drawable material, they may be entirely undrawn, partially drawn or fully drawn, or the tow may be made up of any combination of such filaments. If desired, the continuous filament bundles or tows may be subjected to a preweakening treatment, such as by partial fusion, partial solution or by any other suitable means at intermittently spaced points prior to the drafting and breaking steps of this invention.

When undrawn nylon or other cold-drawable material comprises the filaments of the tow to be stretch-broken by means of this invention, the staple-length fibers produced are characterized in general by the shape depicted in Figure 9. Starting from the lead end of the fiber, there is a section of minimum diameter which is fully drawn, designated by the reference numeral 60. This section may be extremely short or fairly long, depending on whether the break occurred near the back roll or at some other location between the two sets of rolls. Next, there will be a tapered section, designated 62, which at one end may be substantially entirely undrawn and of the maximum diameter and, at the other end, substantially completely drawn and of minimum diameter and therebetween all degrees of drawing from undrawn to substantially drawn. This portion is thus formed because, when the lead end of the fiber is broken, the portion that has not yet passed through the nip of the back rolls is undrawn and cannot be subjected to drawing until the lead and of the filament reaches the nip of the front roll. If the drawn portion of the lead end of the filament is very short, then the undrawn section that follows will be caught by the nip of the front roll before any substantial drawing can take place. A little further along, however, more drawingtakes place until, at the time of breaking, all of the following filament which exists between the bites of the two sets of rolls, and designated 64, will be substantially'fully drawn and of minimum diameter. In fact, there will be an infinite number of shapes, and the relative portions of these three sections constituting the fiber will vary greatly, depending on the location or the lead end and the following end or the fiber when the breahoccurs. The two ends or the fiber will always be substantially completely drawn but may be extremely short as, for instance, 0.1 inch or less, or may be several inches in length. It the lead end oi the fiber is substantially completely drawn for somedistance due to breakage near the front roll, there may be no portion of the fiber that will remain substantially completely undrawn, and such a fiber may have the shape such as is depicted in Figure 10.

straying the continuity of the tow and silver and theparallelism oi the fibers, and a top is produced from which yarn can readily be spun and in which the individual fibers have varying afllnity for dyestuil's so that many variegated colors and shades can be produced by dyeing the yarn in a single dye bath. Because there is excellent overlapping of fiber ends in the top, it is possible to draw the top down to an acceptable yarn with fewer subsequent drawing, blending and twisting steps than have previously been found necessary, with substantial savings in spinning cost. Furthermore, I

finer, stronger yarns can be made due to the excellent distribution and overlappi of fiber ends.

While this invention hasbeen described more specifically in terms or converting nylon tow and the like to top, it is also applicable to any type of continuous filament tow, whether the filaments constituting the same are cold-drawable or not, as

for instance, viscose rayon, cellulose acetate 8 f .rayon or other cellulosic or synthetic filamentous structures,toobtainatoporrovingwithimproved distribution or fiber ends.

Since it is obvious that many changes and modifications can be made in the above-described details without departing from the nature. and spirit of the invention, it is to be understood that the invention is not to be limited thereto except as set forth in the appended claims.

I claim: v r

1. An apparatus for converting tow to top by the stretch-breaking method, which comprises retaining rolls and drawing rolls, said retaining and drawing rolls being positioned relative to each other to provide therebetween a reach varying in length from end to end.

2. An apparatus for converting tow to top by the stretch-breaking method, which comprises retaining rolls and drawing rolls angularly disposed relative to each other to provide a reach therebetween varying in length from end to end.

3. An apparatus for converting tow to top by the stretch-breaking method, which comprises retaining rolls and drawing rolls angularly disposed with respect to said retaining rolls to provide a reach therebetween varying in length from end to end.

4. An apparatus for converting tow to top by the stretch-breaking method, which comprises a set oi retaining rolls and two sets of drawing rolls, each of said setsot drawing rolls being positioned relative to said retaining rolls to receive a separate group 01 fibers and angularly disposed with respect to said retaining rolls to provide a Leach therebetween varying in length from end end.

5. An apparatus for converting tow to top by the stretch-breaking method, which comprises retaining rolls and drawing being irusto-conical in shape and positioned relative to said retaining rolls to provide a, reach varying in length from end to end between said retaining rolls and said drawing rolls.

, VERNAL R. HARDY.

rolls, said drawing rolls

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