US2061021A - Elastic yarn and method of making the same - Google Patents

Description

\ Nowfl, 1936. I F. D. CHITTENDEN ET AL I 2,

ELASTIC YARN AND METHOD OF MAKING THE SAME Filed April 1, 1936 INVENTORS Patented Nova 17, 1936 UNITEDSTATES PATENT oFFI ELASTIC YARN AND METHOD OF MAKING THE SADIE Application April 1, 1936, Serial No. 22,100

3 Claims.

This invention relates to a'balanced, singlecover elastic yarn and to a novel method of making the same.

The Boutwell H. Foster Patent No. 2,024,156 discloses and claims a balanced, single-cover elastic yarn formed by supplying a pre-twis'ted rubber core and a drafted roving of fibres to spinning mechanism and spinning. the fibres about the twisted core as a cover. The eifect of the spinning operation is to remove part but not all of the twist from the core as the cover is spun thereupon so as to produce an elastic yarn in which the twist ofthe core in one direction balances the helical windings of the cover in the opposite direction. A second Foster Patent No. 2,024,155 discloses a balanced, single-cover elastic yarn described as formed by supplying a pretwisted rubber core to winding mechanism which winds 9. covering yarn about the core in the reverse direction to the twist of the core.

In accordance with the disclosure of these two patents, the rubber core is pre-twisted, that is, the core is twisted in one direction before the cover is wrapped helically thereupon in the opposite direction. In accordance with the present invention the rubber core is not pre-twisted but a covering yarn is wound helically about a straight untwisted rubber core. This produces an unbalanced elastic yarn, but the unbalanced condition is corrected by twisting the elastic yarn in a direction to decrease the helical coils upon the core and impart a counter-balancing twist to the core. The correcting twist imparted to the unbalanced elastic yarn should be just enough to balance the yarn so that it will hang free and straight in the skein without kinking. It is found in practice that one twist imparted to the core as herein contemplated will balance a number of oppositely wound coils of the cover. Therefore, the operation of balancing the yarn as herein contemplated does not remove enough coils from the cover to appreciably disturb the covering properties of the helically wound cover as first applied to the core.

One important property of the elastic yarn of the present invention results from the fact that the rubber core has relatively few turns per inch and is therefore under less internal stress than a highly twisted core. It will therefore last longer and will retain its elastic properties better than a highly twisted core. Another important property of this elastic yarn results from the fact that the low twists of the core and high number of helical coils of the cover produces an elastic yarn that may have an elongation of three hundred from a spool l l.

. may unwind from this spool is controlled by causpercent (300%) or more. A further feature of the invention resides in a well covered and easily manufactured elastic yarn that retains its balanced condition well.

The elastic yarn of the present invention and method of making the same will be more fully understood from the following'description and accompanying drawing wherein:

Figure 1 is a side elevation of mechanism for applying a single cover to an elastic core;

Figure 2 is a side elevation of 'mechanismfor balancing an unbalanced elastic yarn;

Figure 3 is a side elevation of a modified form of mechanism whereby the operations of Figs. 1 and 2 may be performed continuously;

Figure 4 is an enlarged side elevation of a single-cover elastic yarn which may ,be produced upon the mechanism of Fig. 1; and

Figure 5 is a similar view of the elastic yarn of Fig. 4 after it has been balanced by being treated upon the mechanism of Fig. 2.

In carrying out the present invention the elastic core l0 may be made by any suitable or known method of producing a strong durable rubber thread, but the core shown is round in crosssection and is preferably formed of an extruded aqueous dispersion of rubber, in accordance with the disclosure of the Hopkinson and Gibbons Patent No. 1,545,257 granted July 7, 1925.

Various types of winding mechanism may be employed for winding a cover helically about the rubber core l0 and in accordance with the disclosure of Fig. 1 the rubber core I0 is supplied The rate at which the core ing the supply of thread wound upon the spool to rest upon a roller it which may be driven at a constant speed. The rubber core Ill is shown as extending upwardly through a hollow spindle l3 which is rotatably supported in the bracket orframe It and the spindle may be driven by the belt ill or by other means as desired.

The covering yarn 16 may be supplied by a package ll wound upon a supporting tube it, and difierent forms of mechanism may be employed for delivering the yarn 16 from the pack age I? to the core-covering position. This is accomplished in the construction shown by placing the tube l8 upon an adapter 19 of well known construction and having the head 20. The adapter is placed upon the spindle l3 to be rotated therewith. Upon the head 20 in the present construction is rotatably mounted a disc flyer 2| which may have a thread-guiding notch or opening at its outer edge. This disc serves to hold that one twist imparted to the core I0 will serve the yarn 16 out of engagement with the head 20 as it is delivered to the core and the disc turns freely upon the head to control the tension of the yarn.

The rubber core 10 is maintained under any desired tension during the covering operation, in the construction shown, by passing the covered or elastic yarn 22 between the cooperating rollers 23 and 24 which are driven by the roller 25 at a sufficiently higher surface speed than the roller I2 to stretch the core I0 the desired amount. The covered yarn 22 passes from the roller 24 through traversing mechanism 26 which guides it to the take-up spool 21, that is driven by the roller 28. v

The rubber core 10 wound upon the spool H is in a straight; that is, untwisted condition, and it will therefore be seen that the effect of windingthe coveringya'rn 16 upon the stretched untwisted core II will be to produce an unbalanced elastic yarn, such as shown in Fig. 4.

In order to balance the yarn 22, the'spool 21 with this yarn wound thereupon may be transferred from the position in which itis shown in Fig. 1 to the spindle 29 of Fig. 2 where it is designated by 213:. The spindle 29 may be driven at the proper speed by any suitable means such as the electric motor 290:. As the unbalanced elastic yarn 22 is unwound from the spool 213:

Hi. It will, therefore, be seen that in twisting the elastic yarn 22 of Fig. 4 to balance the same it is necessary to remove only about 1/10 to 1/20 of the coils shown in Fig. 4 while twisting the core l0 sufficiently to produce the balanced elas- =tic yarn of Fig. 5, and since the covering yarn i6 is applied while the core is stretched and is wound tight upon the core to hold it stretched, the expansion of this core laterally during the balancing operation will serve to take up all slack which may result from slightly untwisting the cover.-

Elastic yarn constructed in accordance with the present invention due to the smallamount of twist imparted to the core maintains its balanced condition well and is well adapted for use where a low-tension long-stretch yarn is desired, for the core may be stretched less than 10% in the relaxed or normal elastic yarn of Fig. 5 and this yarn may be capable of stretching over 300% from the normal condition without breaking either the core or cover.

The properties of thepresent yarn will be further understood from the following table in which four sample yarns are analyzed. It is to be understood, however, that the specifications of this table are not given with any intention of limiting the invention more than is required by the scope of the prior art.

Analyses of single-cover elastzc yarns Sample No. 1 N0. 2 No. 3 I No. 4

Core 75's round 37's round 44's round 75s round. Cover 1-36/1 cotton 3-50/2 cotton 3-80/1 cotton 1-24/1 cotton. Wraps of covering per inch of elastic yam 8O 40 75 83 Twist in core per inch of elastic yarn 9 5 12 18 Length of bare core per yd.

elastic yarn 34 27" 21" 30 Percent core- 51 46 66 36 Percent cover 49 54 44 64 Yards in one pound of elastic yarn relaxed 3400 900 2000 2500 Elongation or stretch of the elastic yarn 330% 250% 250% 265% Note-The size of the rubber core is indicated by the number that may be laid side by side to form one inch.

of Fig. 2 it passes upwardly about the head of the spool 21m to a guide eye 30 and then upwardly to the yarn tensioning or take-up pulley 3| about which it is looped. The yarn upon leaving this take-up pulley passes through traversing mechanism 32 and may then be wound upon the skein receiving drum 33 driven by the friction roll 34. The take-up pulley 31 is preferably driven at a surface speed several times faster than the surface speed of the drum .33 and the slippage of the yarn about this pulley will compensate for variations in the stretch of the elastic yarn being withdrawn from the supply spool 21a: so that the yarn will be delivered to the drum 33 underpractically constant tension. Thethread guides 35 and 36 are preferably provided to guide the elastic yarn 22 to and from the take-up pulley 3|.

The rotation of the spindle 29 should be in a direction to remove a few spiral wraps per inch from the elastic yarn 22 and at the same time impart a few reverse twists to the core III, as willbe apparent from Fig. 5. As above stated, it is found necessary to impart only a relatively few twists to the elastic yarn of Fig. 4 in order to. twist the core as shown in Fig. 5 sufiiciently to balance the large number of helical coils of the covering yarn 16. For example, it .is found to balance from 5 to 10 helical coils of the yarn In most cases it will be desirable to carry out the operation of covering the elastic core upon one machine (such as shown in Fig. 1) and of counterbalancing the unbalanced elastic yarn on a separate machine, such as shown in Fig. 2, because the operation of covering the core shown in Fig. 1 is much slower than that of correcting the balance of the yarn as shown in Fig. 2. However, if desired, these two operations may be carried out continuously by employing mechanism such as shown in Fig. 3 wherein the mechanism for covering the elastic core may be identical with that shown in Fig. 1 and after the elastic core is covered it may pass upwardly between the cooperating of pinch rolls 31 and 38 which are driven at the desired speed. This yarn may then be led downwardly from the roll 38 to the guide eye 39 upon the axis of spinning mechanisms, and from this guide eye to a traveler 40 mounted'upon the usual ring 4| of the ring and traveler type of spinning mechanism, whereupon the yarn may be wound upon the spool or package '42 mounted upon the spinning spindle which spindle may be driven by a belt 44.

Having thus described our invention what we claim and desire to protect by Letters Patent is:

1. The method of making a balanced, singlecover elastic yarn which consists in wrapping yarn helically about a straight rubber core while the latter is stretched to produce an unbalanced elastic yarn, and then twisting the unbalanced yarn in a direction to impart a sufllcient reverse twist to the core to balance the elastic yarn.

2. The method of making a balanced, singlecover elastic yam which consists in wrapping yarn helically about a straight rubber core while the latter is under tension to produce an unbalancedelastic yarn, and then balancing this elastic yam by twisting the unbalanced yarn in a direction to decrease the coils of the cover by not more than 20% and impart a reverse twist to the core.

3. The method or making a balanced, singlecover elastic yarn which consists in wrapping a textile filament helically about a straight rubber core to produce an unbalanced elastic yarn. and

then balancing this elastic yarn by imparting a relatively few twists to the elastic yarn in a direction to decrease the helical coils upon the core and impart a reverse twist to the core.

FAYE'I'I'E n. CHI'I'I'ENDENJ 10 m J. RUPPRmHT.

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