US2249759A - Thread twisting - Google Patents

Description

July 22, 1941. c. F. GRAM THREAD TWISTING 1940 2 Sheets-Sheet 1 Filed Feb. 19

jwue/Mm CARL 62AM al'tonuu July 22, 1941. c. F. GRAM 2,249,759

THREAD TWISTING Filed Feb. 19, 1940 2 Sheets-Shes; 2

CHAF GPA/v Gum M4 1 .direction, ,as' viewed from above.

Patented July 22, 1941 THREAD TWISTING Carl F. Gram, Elizabethton, Temp, assignor, to

North American Rayon Corporation, New York, N. Y., a corporation of Delaware Application February 19,1940, Serial No. 319,774

17 Claims.

This invention relates to yarn twisting methods and apparatus, and in particular to upstroke twisting of artificial filaments. 1

The upstroke twisting process is one in which the untwisted yarn is fed from a spool on a vertical revolving spindle, through a gathering guide, up and over a guide member, and on to a takeup spool which is rotated about a horizontal axis. Twisting takes place as the yarn in the form of a balloon is rotated by the vertical spool and progresses linearly over the guide member. A visualization of the twisting operation can be obtained by considering a vertical length of yarn which has its upper end restrained, as by the take-up spool, and its lower end turned around its own axis. The ballooning of the intermediate portion of the thread is due to the action of centrifugal force. Fundamentally, the same operation is reproduced when the upwardly traveling yarn is unwound from the vertical spool.

It has been found, however, that woven and dyed rayongoods produced from yarn which has been twisted by the upstroke twisting process did not possess the desired uniformity owing to physical irregularities or defects in the twisted structure of the yarn. In the art, one of the most serious defects of this nature is known as corkscrews, and these corkscrews have been classified into several well defined types.

Before going into the classification of corkscrews, consideration will first be given to the frictional forces which produce them. A righthand or 8 twist is produced by turning the twisting spool to the right or in a counterclockwise With the ordinary ring guide, the guide may be considered as a straight rod tangential to the thread at the point of contact, since the guide radius is relatively large in comparison to the yarn in diameter. It will be apparent that the length of yarn between the yarn supply spool and the guide is dependent upon the revolving speed of the balloon and the internal circumference of the guide.

From the standpoint of a single filament, the force L tends to drag the filament downwardly with respect to the upwardly moving yarn body and to produce an elongated length of filament due to the new and steeper angle of wind. This initial looseness of-the filament gives the force L an improved surface of attack on which it proceeds to continue stripping this filament backwards (or preventing it from going forward, since it piles up against the bottom of the guide) while duces the most marked irregularities in the finished dyed goods.

The lateral forces is responsible for a phaselagging of a single filament, but the filament so attacked tends to maintain approximately the same angle of wind. A slight extra length is made available,.and this sometimes remains as a loosely wound, short filament loop. This type of defect is also a corkscrew, but of a more harmless variety. Its magnitude depends upon the duration of attack as well as upon the force. The forces L, S and R always act together and assist each other. Thus the elimination of frictiona1 force L leaves only the type of corkscrew formed byfrictional force S. The corkscrews formed by thread guides hitherto employed in the turning, around its own axis with the same speed of revolution as the balloon and with substantially the same speed as the spool. The first of these frictional forces, which will be designated L, is a linear one along the axis of the yarn and revolutions of the yarn around its own axis. A--

third force acting'on "the thread or yarn is the result of the rotation of the thread within a cirart were always a result of fractional forces S and L.

The corkscrew" which is due to relative longitudinal motion and the corkscrew which results from relative lateral motion of the yarn end come in contact with a portion of the guide which isspaced from thhe thread or yarn. In

' other words, a zi-twist corkscrew may be procular or otherwise curved thread guide. This latter force will be designated S, and is directly duced' on an S twist thread. This type is fairly rare but produces serious defects such as slubs in the finished cloth.

There are then three common forms of corkscrews due to mechanical action of the thread guide on the yarn, namely, a long form produced by relative linear motion and in the direction of twist, another, but shorter, form due primarily to the relative lateral action of a stationary encircling surface on the yarn, and the broken filament form which is folded back and wound in an opposite direction to the twist. The first and third forms are highly'objectionable because they result in a thread having long constrictions causing thin places in the cloth, or slubs causing defects in the cloth.

Broadly, the purpose of the present invention is to improve the upstroke twisting process soas to eliminate loops or corkscrews and other similar irregularities.

More particularly, it is proposed to reduce substantially, or to eliminate completely, all damaging friction on the yarnbody while it is beln guided during twisting.

From the apparatus standpoint, this invention contemplates a novel form of stationary helical thread guide.

Other detailed objects will appear in the ensuing description of the preferred mode of practicing the method and the preferred forms of apparatus.

In its broad method aspects, the invention comprises guiding the yarn in such a manner that no relative longitudinal motion takes place between the yarn and the guiding means. This is accomplished by providing a helical guiding surfacewhose helix conforms to the natural helixformed by any point of the yarn as it is twisting-to gather the balloon and by providing moving surfaces whose linear speed is equal to that of the yarn, at points where the use of a helical surface is not mechanically possible.

The novel apparatus includes in combination with a thread guide comprising a relatively thin rod having a number ofhelical turns of uniform pitch with a special or stabilizing bend leading thereto, another frictionless guide member in the form of a roller. The stabilizing bend is for the purpose of preventing knocking of the yarn balloon on the support for the thread guide and for introducing the yarn into said guide with the minimum amount of friction.

Reference is now madeto the accompanying drawings, in which Fig. 1 is a front elevation of the essential parts of an upstroke twisting machine;

Fig. 2 is a side elevation of the same machine with certain parts shown in section;

Fig. 3 shows in plan view a preferred form of gathering guide;

Fig. 4 is a side elevation of the gathering guide V shown in-Fig. 3;

Fig. 5 is a plan view of a modified form of gathering guide; and v Fig. 6 is a side elevation of the modified gathering guide of Fig. 5.

There is shown in Figs. 1 and 2 of the drawings, apparatus suitable for accomplishing the novel method described herein. This apparatus comprises, for purposes of illustration, the essential members of an upstroke twisting machine. A driven twisting spindle l0 vertically supports a supply spool l2 having wound thereon a body of untwisted yarn I 4. In vertical alignment with the spindle In is a novel form of thread guide l6, which will be described with greater particularity at a subsequent point. The partially twisted yarn or thread l4- leaving the guide I6 is run over a guide member l8. illustrated as a grooved frictionless roll having the outer extremity of its groove in vertical alignment with the center line of spindle Ill. The guide l6 and frictionless roll I8 are supportedln spaced relation above the twisting spool I2 by a bra cket26 mounted on a fixed frame member 2l. After the thread l4 makes a nearly'right angle bend at the roll l8, it passes through a frictionless roller traverse guide which is attached to a reciprocating traverse bar 24 supported for'movement' parallel to the axis of a horizontal take-up spool 26. The

guide 22 includes two frictionless rollers 22a and 22b positioned parallel to each other and in spaced relation. The thread passes between these rollers and. owing to the-free rotatable movement of the rollers, nofriction is, produced upon contact of the thread with either one of the rollers.

As is customary in such machines, the traverse bar 24 is suitably reciprocated by a mechanism which is not shown, and the take-up spool 26 is rotated in the direction indicated'in Fig. 2 by a pair of friction drive rollers 28 rotating with a driven shaft 30. A pair of grooved rollers 32 enand gathered by the thread guide l6.and guide roll 18. From what has beensaid, it will be understood that the twist per unit of length which is given to the yarn by the twisting apparatus depends upon the linear rate of advance of the yarn, or the take-up speed, and the revolutions per unit time of the twisting spool I2. By way of example, a take-up speed of 2,000 inches per minute and a twisting spool speed of 6,000 revolutions per minute will be assumed. Under these conditions, the yarn will be given a twist of three revolutions or turns per inch. As previously explained, the direction of'twist is determined by the direction of rotation of the twisting spool l2. Every point of a thread so twisted describes a spiralwhich has a lead of one 'third inch, along the path of the thread. When it is desired to give the yarn for example 5 turns per inch, the lead of the spiral will be one-fifth inch.

etc. In other words there is a distinct relation between the number of turns per inch put into the yarn, and the lead of the helix of the thread guide since the lead will be made thereciprocal value of the average number of turns twist to be imparted to the yarn. Expressed mathematically where l is lead and where n is the number of' turns twist per unit length. It is to be understood that lead means the progress of the yarn of that path, in one revolution.

The character of the thread guide l6 of this invention is determined by the direction and number of turns per inch which it is desired to impart to the yarn. This is in sharp distinction to the previous practice of using a simple ring or random pigtail.

Since the guides l6 and I60, which are illustrated in Figs. 3, 4, 5 and 6, are intended for producing three right-hand or 8 turns per inch, the

along its path, regardless of change of direction I helical portions are of uniform lead, one-third inch, and comprise one and one-quarter turns, with the upper end terminating on the helix. The turns of each helix are right turns in that they progress upwardly and to the right, as seen in the elevations of Figs. 4 and 6. A minimum number of turns necessary to guide the yarn in its natural spiral path is used, in order that the time of contact can be made as short as possible. When the yarn is being given three turns per inch, it will contact theinside of the helix portion of this guide only at longitudinally spaced points which are one-third of an inch apart. The intermediate points will not contact the helix of the guide, nor be subjected to the laterally frictional forces therein. Each succeeding one-third inch length of yarn will progress upwardly through the guide in the samemanner. .Guides I6 and I 60 have helix portions with internal diameters of approximately one-quarter inch, a practical minimum being used for its effect on the lateral force S, holding the internal circumference to a minimum length. I

Where the term number has been used with respect to the helical turns of. the guides I 6 and I60, it is intended to mean one or more. While the irreducible minimum in practice appears to be one and a fraction, one and one-quarter turns being now preferred, it must be realized that a plurality of whole turns may occasionally be found advantageous.

By guiding a thread in this manner substantially, all relative longitudinal motion between the threacl and its guide will be eliminated, and the lesser frictional forces which have been denoted S and R will be greatly reduced by th nature and limited extent of contact.

Reference is now made to the horizontal, extended portion .or support IT, or Ill, which forms a part of the illustrated guides. When the support portion is connected directly to the bottom of the helix portion or projects straight and radially as a continuation thereof, it has been found to interfere with the balloon and to provide another serious source of both longitudinal and lateral friction. To eliminate this friction source and further to improve th quality and uniformity of the twistedyarn a bal- Icon-stabilizer or stabilizing bend was evolved.

The first approach to this problem of balloon" interference or knocking against the guide supporting rod (H or MI) was to add an extra halfloop I9l to the bottom of the helical spiral. This half-loop is of a larger mean diameter than the helical portion and is located eccentrically with respect to the vertical axis thereof. It is disposed so as to ensnare the yarn balloon 180 degrees ahead of the supporting rod Ill and to press it gently downward in such a manner that the free part of the balloon will swing out below the supporting rod and thus clear it. A further function of the stabilizer loop is to engage that point of the thread which will contact the helical spiral a half-revolution later. The locus of this point can be determined geometrically, and the half-loop I9I is so shaped that the approaching yarn point will travel in constant contact with it and thus be free from linear friction.

The stabilizer bend (l9 or ISI) may be compared with a true spiral of Archimedes of which it is an adaptation. It has, therefore, a constant rate of approach radially toward the helix porti n of th guide (I6 or I60) The fundamental feature of the helical guide is e ended to the dicate that very slight longitudinal relative mostabilizer bendby distorting the Archimedes spiral into a three-dimensional convolution which is semi-circular in plan and has every point on its yarn contact surface or its center line a constant distance (the lead of' the helix, namely, one-third inch) from the yarn contact surface or center line of the lower-most and closest helix tum.

A, further development of the guide consists in extending the half-loop stabilizer into a full horizontal loop I9 for 315 degrees around the axis of. the vertical spiral guide, maintaining the principle of the spiral ofArchimedes, and continuing this spiral tangentially radially thereafter to form an integral supporting rod I! for the entire thread guide I6. This is the preferred embodiment shown in Figs. 3 and 4, and in which the guide is self-threading and balloon-retaining. Without the full loop IS the balloon may sometimes run out of the guide with damaging results to the yarn.

For all practical purposes, the inner 180 degrees of the full stabilizer loop I9 or the halfloop l9l may be shaped so as to lie in two planes which intersect midway around, that is, the degree point. Figs. 3, 4, 5, and 6 are illustrative of this more easily bent and practical form.

- The herein disclosed method and the preferred embodiment of apparatus for practicing that method afford a simple and accurate control of the upstroke twisting operation. In the case of artificial yarns'such as rayon, they produce a uniform thread which is substantially free from twisting defects having the nature of corkscrews, and loops. Principles have been established which are applicable to any similar problem of guiding a thread for twisting.

The apparatus which has been described represents the presently preferred means of accomplishing the twisting operation, and is characterized by a definite relationship between the direction and pitch of the thread ,guide and the degree of twist imposed upon the thread or yarn. Novel and efllcient means in the form of a stabilizing loop has been devised for introducing the yarn into the thread guide Without causing any undesired relative motion.

Through the medium of this invention rayon goods can be greatly improved in quality without departing from the normal production twisting speeds of 5,000 revolutions per minute and upward. Extensive tests have demonstrated that commercially corkscrew-free twisted yarn can be produced in upstroke twisting at high speeds.

It should be understood that the foregoing exemplifications of the present invention in its application to the specified operations are simply illustrative of various similar applications of the invention involving the principles herein set forth. Modifications and variations of this invention will readily be recognized in the art, and it is desired to include all modifications and variations coming within the scope of the appended claims. In these claims the terms substantial and substantially" respectively are used to intions may occur which, however, are of a magnitude insuflicient to detrimentally affect the textile qualities of the twisted yarns.

I claim:

1. That improvement in upstroke twisting which comprises leading a yarn over guiding means without substantial relative longitudinal motion between any point on the yarn and the guiding means While the yarn is in contact with the guiding means and is being twisted.

2. That improvement in upstroke twisting of a yarn which comprises guiding the yarn over a spiral guide surface having substantially the same lead and direction as the natural helical path described in space by any point on the yarn while it is being guided.

3. That improvement in upstroke twisting which comprises guiding the yarn by means of a spiral guide the lead of which is the reciprocal value of the average number of turns twist imparted to the yarn and the direction of which is the same as that of the natural helix described in space by any point on the travelingyam.

4. A method of substantially eliminating relative longitudinal motion between any point on a yarn and the guide in upstroke twisting which includes the step of supporting spaced points on the yarn by. means of a spiral guide whose spiral corresponds to the natural spiral described in space in the guiding region by any point on the traveling yarn.

5. A method of substantially eliminating relative longitudinal motion between a yarn and its guide in upstroke twisting which includes the step of guiding the yarn by a stationary spiral surface which corresponds in shape to the natural spiral described in space by any point on the yarn in the guiding region during the upstroke twisting operation.

6. A method of substantially eliminating relative longitudinal motion and minimizing relative lateral motion between a yarn and its guide in upstroke twisting which includes the step of supporting only constantly spaced points on the yarn in a spiral path which corresponds to the natural spiral described in space by any point on the yarn in the guiding region during the upstroke twisting operation.

7. A thread guide comprising a rod having a number of helical turns of uniform pitch and a stabilizing bend leading thereto, said stabilizing bend having the shape of a spiral of Archimedes which has been modified in elevation so that every point thereon is substantially equidistant in space from the nearest portion of the closest helical turn.

8.- A thread guide comprising a rod having a number of helical turns of uniform pitch and a full-loop stabilizer leading thereto, said stabilizer having the shape of a spiral of Archimedes which has been modified in elevation so that every point thereon is substantially equidistant in space from the nearest portion of the closest helical turn.

9. A thread guide consisting of a rod having a number of helical turns of uniform pitch and a full-loop stabilizer leading thereto, said stabilizer having the shape of a spiral of Archimedes which has been modified in elevation so that every point thereon is substantially equidistant in space from the nearest portion of the closest helical turn, the stabilizer having a supporting portion extending from its outer end.

10. A thread guidecomprising a rod having a number of helical turns of Imiform pitch and a half-loop stabilizer leading thereto, said stabilizer having the shape of a spiral of Archimedes which has been modified in elevation so that every point thereon is substantially equidistant in space from the nearest portion of the closest helical turn.

11. A thread guide comprising a relatively thin and smooth, circular rod having a number of helical turns of uniform pitch and an outwardly spaced stabilizing bend leading thereto, said stabilizing bend having approximately the shape of a spiral of Archimedes.

12. A thread guide comprising a polished, stainless steel rod having a number of helical turns of uniform pitch and a stabilizing bend leading thereto, said stabilizing bend having the shape of a spiral with an approximately constant rate of approach radially toward the axis of the helical turns.

13. A self-threading thread guide consisting of a rod having a small number of helical turns of uniform pitch, a full-tum stabilizing bend leading thereto. and an extended supporting portion projecting from the outer end of the stabilizing bend, said stabilizing bend having the shape of a spiral of Archimedes which has been modified in elevation so that every point thereon is substantially equidistant in space from the nearest portion of the closest helical turn.

14. Thread guiding means comprising a contlnuous spiral surface for supporting longitudinally spaced points on a thread, said surface having a helical portion of uniform pitch and a portion leading thereto which has an approximately constant rate of approach radially toward the axis of the helical portion for preventing interference and friction as the thread enters the guiding means.

15. Thread guiding meanscomprising a continuous, curved surface for supporting longitudinally spaced points on a thread, said surface having a helical guide portion of uniform pitch and a spiral portion of greater mean diameter than the helical portion leading thereto for threading the guide portion.

16. In an upstroke spinning apparatus, a twisting spool, a spiral thread guide spaced above said spool with its axis concentric therewith, and a frictionless guide disposed above the helical guide and in alignment with thespool and said helical guide for changing the direction of an upwardly moving thread and serving as a point about which twisting takes place, said spiral thread guide having a numben of helical turns of uniform pitch and a spiral stabilizer bend of greater mean diameter than the helical turns for threading the 1 guide.

17. In an upstroke spinning apparatus, a twisting spool, a spiral thread guide spaced above said spool with its axis concentric therewith, and a frictionless roller disposed above the helical guide prising a number of vertical helical turns of uniform pitch surmounting a stabilizing bend having the shape of a spiral of Archimedes distorted in elevation so that every point thereon is approximately equidistant in space from the nearest portion of the closest helical turn.

' CARL F. GRAM.

Certificate of Correction Patent No. 2,249,759. July 22, 1941.

CARL F. GRAM It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 60,

for i=5 read Z=%; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 24th day of March, A. D. 1942.

[SEAL] HENRY VAN ARSDALE,

Acting Commissioner of Patents.

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