US2455173A

US2455173A - Yarn treating apparatus

Info

Publication number: US2455173A
Application number: US672259A
Authority: US
Inventors: Ira V Hitt
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1946-05-25
Filing date: 1946-05-25
Publication date: 1948-11-30
Anticipated expiration: 1965-11-30
Also published as: GB637593A; DE951290C; FR962278A

Description

Nov. 30, 1 948. I |.v. HITT $455,173

YARN TREATING APPARATUS Filed lay 25. 1946 Patented Nov. 30, 1948 2,455,173 YARN TREATING APPARATUS Ira V. Hitt, Waynesboro, Va., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware Application May 25, 1946, Serial No. 672,259

14 Claims.

This invention is concerned with apparatus for successively stretching and relaxing products and particularly filaments and yarns which are capable of considerable permanent elongation under stress, particularly at elevated temperatures.

Polyacrylonitrile and other polymers of acrylonitrile containing at least 85% by weight of acrylonitrile in the polymer molecule, while insoluble in common solvents, will dissolve in dimethyl formamideand some other organic compounds. These polymers may be converted into filaments, yarns and other productsby extrusion of their solutionsthrough suitable forming dies into liquid or gaseous media which will coagulate the polymer from solution. Filaments and yarns formed of these acrylonitrile polymers by wet or dry spinning processes which do not involve substantial stretching of the coagulated filaments are not satisfactory for textile operations since they possess a relatively low dry tenacity, of the order of about 0.5 to 1.5 grams per denier. These low tenacity acrylonitrile polymer yarns also possess after aging a low dry 2 to apparatus for processing polyacrylonitrile filaments and yarns, but it will be understood that the invention includes within its broad scope the processing of filaments and yarns composed of other polymers of acryionitrile. particularly those composed of or containing in the polymer molecule at least 85% by weight of acrylonitrile as well as other types of synthetic yarns and filaelongation, of the order of 5% to 10%, then the dried yarns cannot be stretched to any appreciable extent at ordinary temperatures without breaking. The copending application of Daniel T. Meioon Serial No. 496,397, filed July 28, 1943, describes a process for greatly increasing the tenacity of these acrylonitrile polymer yarns by heating the yarns to a temperature of 100 C. or more and then stretching them very consid erably, e. g. from four to ten times their unstretched length, thereby obtaining products having a dry tenacity of 3.0 or more gramsper denier, the dry elongation being moderately low, e. g. 8% to 12%. The copending application of Shirler'gh Silverman Serial No. 496,396, filed July 28, 1943, now Patent Number 2,445,042, describes the relaxing at temperatures of 80 C. and above, of these stretched acrylonitrile polymer yarns to effect shrinkage of the yarn and thereby to increase elongation. The apparatus heretofore available for use in the said processes described in the said copending applications of Meloon and Silverman have the disadvantages that the filaments undergo considerable mechanical Ldamage due to the stresses applied during stretching, and

the control of stretching and relaxing within the optimum limits is moreover difficult to regulate.

For purposes of illustration, the following description of the invention will be largely directed ments which may be hot stretched to a considerable extent and/or relaxed wfth improvements in their physical characteristics. Although the invention is particularly concerned with apparatus for processig of multifilament yarn, it' may be applied with advantage to monofilaments, films and other products which may be advantageously stretched and/or relaxed.

One object of this invention pertains to apparatus which operates smoothly and uniformly,

uniformly relaxed under closely controlled temperature conditions and wound on suitable collecting devices with very close tension control and with a minimum of abrasion and other mechanical damage to the filaments. Other objects will appear hereinafter.

The apparatus with which the invention is concerned embodies a series of rollers, one or more of which is heated, the rollers being so dis= posed as to feed yarns, without slippage, under a closely controlled tension of a low order of magnitude, to stretching rollers; the yarn, while still heated, passes from the stretching rollers to additional rollers rotating at a reduced peripheral speed where the yarn is relaxed and permitted to shrink, the yarn thereafter being collected on pirns, bobbins or other suitable collecting devices. By suitable heating and arrangement of the rollers, heat is quickly imparted to the yarn as it passes around the respective rollers, thereby permitting uniform stretching and relaxing of the yarn, the rollers being so driven and so disposed with respect to each other as to exert a minimum 3 of pressure against the yarn as it passes between rollers to and from the stretching zone so as to minimize mechanical damage to the yarn, while at the same time preventing slippage and wandering of the yarn across the rollers.

The invention will be more easily understood by reference to the drawings which are not drawn to scale and in which:

Figure 1 represents a diagrammatic view in perspective of a front elevation of one form of thread processing apparatus jwhich can be used in the practice of the invention,

Figure 2 represents a plan view of the apparatus shown in Figure 1,

Figure 3 represents a partial side elevation of the apparatus of Figure 1, showing the course of a number of yarns processed together in parallel on the apparatus,

.Figure 4 represents an elevation viewed from the other side of the apparatus in Figure 1, and Figure 5 shows a perspective view of an auxiliary heating device.

In the drawings like numerals refer to like parts.

Referring to the drawings, a frame l0 rigidly supported in any suitable fashion has journaled therein for rotation shafts H, l2 and I3, mounted respectively in bearings i5, i8 and It, the shafts being independently driven from variable speed transmissions (not shown). Rollers i1, |8 and I8 are mounted on shafts ll, |2.and l3, being fixed to said shafts so as to rotate therewith. Roller is fixed to shaft 2| to be rotated thereby and is driven from shaft II by means of a gear 22 fixed to the shaft 2| of roller 20 which meshes with gear 23 fixed to the shaft ll of roller l'l, the number of teeth on

gears

22 and 23 having the same ratio as the ratio of the thread contacting peripheries of rollers 28 and I1 whereby to insure that rollers 20 and I1 will travel at the same peripheral speed. The shaft 2| of roller 20 is rotatably supported in arms 28 by means of bearings 28 positioned on shaft 2| and mounted for rotary movement in arms 24.

of-roller ii, the ratio of the teeth of

gears

38 and 21 being the same as the ratio of the peripheries of rollers 3| and I8 so as to insure that the said rollers 3| and i3 will rotate at the same peripheral speed. The

gears

36 and 31 are maintained in mesh in normal operation by the canted position of arms 33 which brings the center of gravity of roller 3| between roller i8 and pivot point 3. Roller i8 is heated in a manner similar to roller I! to a temperature normally somewhat higher than that of roller l1. Roller 3| is normally not heated, but may be heated if desired. Roller 3| does not rest against roller I8, but is mounted for normal clearance, in a position closest to roller I8, of a very small amount, not much more than the diameter of the yarn passing between rollers 3| and I8. Roller 3| in normal operation is thus always, positively driven and spaced slightly away from roller i8 and is free to move to accommodate different sizes of yarns and knots or other non-uniformities in the yarn. Roller 38 is fixed to rotate with shaft 39 which is mounted, like rollers 20 and 3|, in arms 40 mounted, like

arms

24 and 33, for pivotal motion on pivot 4| fixed in bracket 42 which is fastened to frame l0. Roller 38 is surface driven from roller l8, being positioned with its center of gravity between roller I8 and pivot 4i so as to bear with some pressure against roller l9, but being free to move away from roller Hi to a limited extent so as to accommodate different sizes of yarn passing between the rollers. Since the stress on the yarn passing between rollers 38 and I3 is less than that between the other F rollers, roller 38 may press against roller ill with Roller |9 normally runs at room temperature,

Arms 28 are supported for movement on a pivot 28 mounted in a bracket 21 fixed to frame Ill, and are normally canted towards roller ll so as to cause roller 20 to rest against roller l1. Bracket 21 and the positions of rollers i1 and 28 can be seen in Figure 1. Roller 20 is chosen of such a weight and is positioned with respect to pivot 23 at such an angle of support as normally to rest against roller |'I with a small amount of pressure, the pressure normally being about one pound.

Gears

22 and 23 will remain in mesh during the normal operation of the apparatus since the center of gravity of roller 28 is between roller I1 and pivot point 28. Roller I1 is heated to any desired temperature, preferably by internal heating, as by means of a heating fluid, and roller 20, while preferably not heated, may likewise be heated if desired.

Roller 28 is mounted at one end for free rotation in bearing 28 disposed in bracket 21 attached to frame I0. Roller 3|, fixed to shaft 32 is mounted similarly to roller 20 in arms 33 supported,

similarly to arms 24, on a pivot 34' positioned in bracket 38 fixed to the frame l8. Roller 28 is canted or askew with respect to roller 3|, so as to maintain the turns of yarn separate as they pass around roller'3l and separator roller 28. Roller 3| is gear driven in the same manner as roller 20 by means of a gear 36 fixed on shaft 32 and meshing with gear 31 fixed on shaft I2 but it may be colder or slightly warmer. Roller 38, while preferably not heated, may also be heated or cooled if desired. Roller 38 can be positively driven from roller Is by intermeshing gears in the manner described with respect to rollers 20 and 3|, but this is normally not required. Rollers 20, 3| and 38 may be pivotably mounted in any suitable way, the pivot point being above or oil to one side; if gravity does not pull rolls together, a spring may be used. The surface drive between rollers 38 and I9 may be effected by providing roller 38 with a resilient surface such as rubber or cork, these rollers serving as feed rollers for feeding the yarn to a collecting device. One form of collecting device is represented by pirns 43 in a ring twister having centering guides M, the ring of the ring twister not being shown in the drawing.

In operation, the yarn 45 (Figure 1) is fed from any suitable source of supply (not shown) such as a bobbin, to roller 20, passing for some distance around roller l l, in the manner shown in the drawings, at a moderate tension. The roller 20 presses against roller H with a pressure sufficient to prevent the yarn from slipping, but insufflcient to cause any mechanical damage to the yarn, one pound total pressure being adequate for most operations. The yarn is heated on roller i1 to a relatively high temperature since elevated temperature facilitates drawing of acrylonitrile polymer yarns, the yarn then passing around separator roller23 and positively driven roller 3| 9, number of times so as to prevent slippage, the turns of yarn being kept separate by the canted or askew with each other as is stated above, roller It being the yarn then passes around roller 3b, betweenrollers 35 and it, around roller is, through centering guide Ml and is collected on pirn iii-i. The

peripheral speed of roller 88 is less than that of roller 58 by an amount suificient to effect the desired degree of relaxation of the yarn. The temperature of roller 33 is less than that of roller is, since this assists in inducing relaxation of the yarn.

By the arrangement described above, yarn can be fed into the apparatus under relatively low tension and can be-uniformly stretched and relaxed, without slippage. By the pivotal arrangement of the gear driven and surface driven rollers, the apparatus can be used without special adjustment with yarns'of different denier since the rollers can move apart tosome extent without disengaging the gears and without damaging the yarns. Lihewise, the rollers may move apart without unmeshing the gears, to accommodate minor irregularities in the yarns. Morever, if yarn wraps should build up on any of the rollers, the pivotally mounted, gear driven rollers may move away from their companion rollers by a distance sumcient to disengage the gears and thereby'prevent damage to the equipment. The surface driven lowermost roller can also move away from its companion driving roller as the yarn wrap builds up.

- The following example illustrates a preferred mode of operation of the invention in connection with the apparatus described above, but it will be understood that it is to be considered as illustrative rather than limitative.

Example unwound from any suitable source of supply such as a bobbin and is fed to roller 2!! at a tension of 3 to 4 grams, at a speed of yards per minute as determined by the peripheral speed of rollers 29 and ill. Roller i! is heated to 150 C. and roller 26 presses against roller IT with a pressure of one pound, without allowance for diminution of the pressure by action of the yarn. The yarn passes more than 180 around roller I! to separator roller 26. around roller 3i and the separator ro ler three or four times and thence to roller i8, heated to 170 C., the peripheral speed of the separator roller and rollers 3i and i8 being 200 yards per minute to impart a stretch of 900% to the polyacrvlonitrile ya n. he r/am then passes succe sively around rollers 38 and i9, having a peripheral speed of 160 yards per minute and being heated to a temperature of 32 C. The tension between rolersi8 and 38 is as low as possible to permit the greatest amount of skrinka-ge of the yarn under the prevailing temperature. After passing around roller 19. the yarn is fed to the ring twister at a tension slightl in excess of the tension between rollers l8 and 38. While particular reference has been made to yarns and filaments composed of polyacrylonitrile, it will be understood that the invention drawings.

may also be applied to any yarn; which can be stretched under the influence of heat and which may be heat relaxed thereafter with advantage. Examples of such other yarns are yarns com posed of nylon or of other linear condensation polymers, of cellulose acetate, of other vinyl polymers such as vinyl acetate including the conjointpolymers composed of vinyl acetate and 25% vinyl chloride. The invention ,isapplied with particular advantage to acrylonitrile polymer yarn in which the polymer contains at least acrylonitrile in the polymer molecule.

The yarn to be stretched in accordance with this invention must be properly ten'sioned before entering the nip between rollers 20 and H. Too low a tension permits thread to wander on the succeeding rollers. This is a particular disadvantage when a number of threads are being processed in the apparatus as is shown in the Wandering of the yarn furthermore may interfere with the obtaining of uniform yarn characteristics. The-amount of tension to be applied depends on the pressure at which roller 293 must be pressed against roller i? to avoid slippage and may be readily determined by experiment.

For ordinary yarns of, say, about 700 denier-40 filament, the amount of tension is in the neighbox-hood or about 3 or 4 grams total tension. When starting the apparatus and after the proper tension has been applied, the package is passed through to the wind-up pirn barrel is so connected.

guide it and secured tit. While the yarn it is passed through the nipof rollers 2t and ii, being manually guided over the top of roller i'i.- When sumcient yarn has been delivered to the side of roller 8'? opposite roller 20, the knee brake on the pirn is released, permitting rotation of the pirn and when the pirn takes up the yarn at the desired rate, the yarn is then passed over and around the separator roller 28 and roller 8! one or more times, then over roller i8 and around rollers 3d and it, and is then released. v

The number of units shown in the drawing and described above for the stretching and relaxing of yarn that can be used on a twisting machine is determined by the pirn spacings on the twister and the number of yarn ends that can be satisfactorily handled over a single series of rollers. This is a question of mechanical design and adaptation of the novel apparatus to any par ticular available equipment.

While the invent on ha been illus ra ed in connection with the collecting of yarn by a ring twister method, it will be understood that any other form of twister can be used. Down-twisters are of particular advantage in the practice of the invention. Other methods of collecting the yarn as it passes through the rollers of the novel apparatus can be used in place of the twister illus trated. For example, the yarn, after passing through a stretching and relaxing unit, can be collected by cap spinners, rotating bobbins, surface driven or directly driven revolving buckets,

slip spindles, etc.

While the rollers of the apparatus are prefer-- ably driven from variable speed transmissions, any suitable driving means may be employed in lieu of variable speed mechanisms. The gear drive between rollers of the same series can be i replaced by other forms of drive, such as chain drive, belt drive and the like.

One mode of heating the rollers is to utilize an internally heated shell or a stationary element around which the roller rotates with an approxiyarn from a take-off mate clearance of 0.006 inch or less, this latter means ofiheat transmission being eflective to produce uniform and rapid heating of the roller. Steam, electricity and other methods of heating can be resorted to.

Additional heat may be applied to the yarnby using a heated metal shoe 48, such as that shown in Figure 5.- This may be mounted concentrically above such a roller as roller i|.- The clearance may be varied, but is normally of an inch. The shoe may be heated electrically as by electrical terminals 41. Shoe temperatures normally used vary from 150 C. to 350 C. depending upon the yarn denier, input speed, the temperature of the particular roller and the clearance between the roller and the shoe. While the physical dimensions of the shoe may be varied over wide limits. it has been found that a shoe two inches wide, 3/ inch thick and conforming to a 137arc on a. 3% inch radius gives the desired results. The heated shoe may be used with any one or all of the heated rollers to aid in heating the yarn during stretching or relaxing procedures or both. The use of such a heated shoe is advantageous in that the maximum yarn input speed at which successful operation is obtained may be doubled. Further, the stretching of heavier yarn bundles is facilitated and the temperature required on the stretching rolls is considerably lower.

As a specific example of the advantages .of this modification, the maximum permissible yarn input speed for producing IOU-40 count yarn was increased from 25 to 45 yards per minute, using the shoe described above at a inch spacing and a shoe temperature of 300 C. at which the electrical energy consumed was about 250 watts. The

energy expended in heating a stretching roller such as roller i! was reduced by an amount corresponding to a reduction of 15 C. in the temperature of this roll, that is, from 150 to 135 C.

The above description has specified the pivotins: of gear driven rollers 20, 3| and 38. Other forms of mechanical motion for imparting the desired degree of movement may be used. The movable rollers may, for example, instead of being pivoted. have a non-rotatable sliding connection with the shafts on which the rolls are mounted; e. g. the rollers may be provided with a rectangular slot allowing for the non-rotatable mounting of the rollers on a square or rectangular shaft, the slot length being sufficiently greater than the cross-sectional width of the shaft to permit the desired amount of movement.

Roller temperatures will be selected in accordance with the degree of stretch desired, the distance between rollers, the size of the rollers, the size and number of threads passing through the apparatus and other variables. The roller I! is generally heated to about 130. to 170 C. with roller l8 preferably but not necessarily being heated to a somewhat higher temperature than roller H, e. g. 10 to 50 higher, and roller 38 will have a temperature somewhat lower than that of roller I8 as a matter of preference to assist in the shrinking and collecting of the yarn. The relative peripheral speeds of the rollers between which the yarn passes will depend, as to the stretching rollers, on the per cent stretch desired and as to the relaxing rollers, on the degree of shrinkage which the yarn will undergo at the temperature conditions prevailing. This degree of shrinkage will ordinarily be around 20% in the absence of tension on the yarn. Generally speaking, larger stretch roller diameters permit the yarn to stretch over a much longer thread length. Roller diameters are generally designed to give sufllcient heating surface to permit yarn speeds up to 300 yards per minute or more at nine to ten times stretch between rollers l1 and Any departure from the design of apparatus and mode of operation described above which conforms to the principle of the invention is intended to be included within the scope of the claims.

I claim:

1. Apparatus for stretching at elevated temp-eratures an extensible material comprising, in combination, a roller, a shaft for driving said roller, a second roller, mechanism connected with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers, a movable mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and a stretching roller adapted to operate at a higher peripheral speed than said first roller.

2. Apparatus for stretching at elevated temperatures an extensible material comprising, in combination, a roller,a shaft for driving said roller, a second roller, gear mechanism connected with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers, a movable mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and a stretching roller adapted to operate at a higher peripheral speed than said first roller.

3. Apparatus for stretching at elevated temperatures, an extensible material comprising, in combination, a roller, a shaft for driving said roller, 3. second roller, gear mechanism connected with said shaitand said second roller for driving said second roller, means for heating at least one of said rollers, a pivoted mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and a with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers, a pivoted mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and two stretching rollers adapted to operate at a higher peripheral speed than said first roller.

5. Apparatus for stretching at elevated temperatures an extensible material comprising, in combination, a roller, a shaft for driving said roller,

a second roller, gear mechanism connected with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers, a pivoted mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and two stretching rollers adapted to operate at a higher peripheral speed than said first roller, one of said stretching rollers being provided with movable mounting means for permitting relative moveglint between said stretching rollers during roa ion.

least one of said rollers a pivotal mounting for one oi said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation and two stretching rollers adapted to operate at a higher peripheral speed than said first roller, one of said stretching I rollers being provided with driving means, the other of said stretching rollers being provided with means connected with said driving means whereby to drive said second roller, one of said stretching rollers being provided with movable mounting means for permitting relative movement between said stretching rollers during rotation.

7. Apparatus for stretching at elevated temperatures an extensible material comprising, in

combination, a roller, a shaft for driving said roller, a second roller, mechanism connected with said shaft and said second roller for driving, said second roller, means for heating at least one of said rollers a movable mounting for one of said rollers permitting peripheral contact -between' said rollers and permitting relative movement between said rollers during rotation, stretching means for extending said material and relaxing means for permitting relaxing of the stretched material. 7

8. Apparatus for stretching at elevated temperatures an extensible material comprising, in combination, a roller, a shaft for driving said roller, a second roller, mechanism connected with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers a movable mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation, a stretching roller adapted to operate at a higher peripheral speed than said first roller and a relaxing roller adapted to operate at a lower peripheral speed than said stretching roller.

9. Apparatus for stretching at elevated temperatures an extensible material comprising, in combination, a roller, a shaft for driving said roller, a second roller, gear mechanism connected with said shaft and said second roller for driving said second roller, means for heating at least one of said rollers a pivoted mounting for one of said rollers permitting peripheral contact between said rollers and permitting relative movement between said rollers during rotation, two stretching rollers adapted .to operate at a higher peripheral speed than said first roller and two relaxing rollers adapted to operate at a mounting means for permitting relative movement between said stretching rollers during rotation and two relaxing rollers adapted to operate at a lower peripheral speed than said stretching rollers, one of said relaxing rolers being provided with movable mounting means for permitting relative motion between said relaxing rollers during rotation.

' IL'Apparatus comprising, in combination, a

roller, means for driving said'roller, a second roller, mechanism connected with said driving means and said second rollerfor driving said second roller at the same peripheral speed as said first roller, means for heating at least one of said rollers movable mounting means for one of said rollers for permitting peripheral contact between said rollers and for permitting relative movement between said rollers during rotation.

12. Apparatus comprising, in combination, a roller, means for driving said roller, a second roller, gear mechanism connected with said driving means and said second roller for driving said second roller at the same peripheral speed as saidflrst roller, means for heating at least one of said rollers movable mounting means for one of said rollers for permitting peripheral contact between said rollers-and for permitting relative movement between said rollers during rotation.

13. Apparatus comprising, in combination, a roller, means for driving said roller, a second roller, gear mechanism connected with said driving means and said second roller for driving said second roller at the same peripheral speed as lower peripheral speed than said stretching rollers.

10. Apparatus for stretching at elevated temsaid first roller, means for heating at least one of said rollers, pivoted mounting means for oneof said rollers for permitting peripheral contact between said rollers and for permitting relative movement between said rollers during rotation.

, 14. Apparatus comprising, in combination, a roller, means for driving seid roller, a second roller, gear mechanism connected with 'said driving means and saidsecond roller for driving said second roller at the same peripheral speed as said first roller, means for heating at leastone of said rollers pivoted mounting means for one of said rollers for permitting peripheral contact between said rollers and for permitting relative movement between said rollers during rotation, said pivoted mounting being adapted to position the center of gravity of the roller mounted thereon betweenthe pivot point of said mounting and said otherroller.

IRA V. HIT'I'.

REFERENCES cr'rnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Jan. 28, 1932