US3081510A - Methods and apparatus for processing yarn - Google Patents

Description

March 19, 1963 N. E. KLElN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4 Sheets-Sheet l INVENTORS NORMAN E. KLEIN F56. -E-

ATTORNEY March 19, 1963 N. E. KLEIN ETAL METHODS AND APPARATUS FOR PROCESSING YARN 4 Sheets-Sheet 2 Filed July 8, 1955 FIG. -2-

INVENTORS NORMAN E KLEI N FRANK E. ROWE,JR. BY M ATTORNEY March 19, 1963 N. E. KLEIN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4 Sheets-Sheet 5 JNVENTORS NORMAN E. KLEIN ATTORNEY FRANK E. ROWE,JR.

March 19, 1963 N. E. KLEIN ETAL 3,081,510

METHODS AND APPARATUS FOR PROCESSING YARN Filed July 8, 1955 4 SheetsSheet 4 IN VEN TORS ATTORNEY NORMAN E. KLEIKN FRANK E. ROWE JR.

United States Patent 3,081,510 METHODS AND APPARATUS FUR PROCESSING YARN Norman E. Klein, Pendleton, and Frank E. Rowe, In, Clemson, S.C., assignors to Deering Millilren Research Corporation, Pendleton, S.C., a corporation of Delaware Filed July 8, 1955, Ser. No. 520,838 (Ilaims. (Cl. 281) This invention relates to improved methods and apparatus for performing processing operations upon a running length of yarn. In its more specific aspects the invention relates to improvements in processes for manufacturing crinkled or coiled yarns having an elastic nature as disclosed in co-pending US. application, Serial No. 274,358, filed March 1, 1952, and to apparatus for performing the improved processes.

The above identified co-pending application discloses a process for making crinkled or coiled yarn which process comprises subjecting the yarn to heating conditions and thereafter passing the hot yarn under low tension through a very sharp angle. The application also discloses suitable apparatus for preparing the yarn which apparatus comprises a flattened heater strip over which the yarn is passed at an elevated temperature and a blade member having an acuate edge positioned in close proximity to the heater strip so that the hot yarn can be passed over the acuate edge to cause the yarn to follow an angular path. While the apparatus disclosed in the above identified co-pending application is capable of producing an excellently elasticized yarn, the apparatus nevertheless leaves room for improvement in several respects.

A first disadvantage of the earlier apparatus is that the flattened strip of metal employed for heating the yarn has a very high heat loss even though insulation is employed where feasible to cover portions of the heater strip. The heat loss is appreciable even when very slow yarn speeds are employed and with higher yarn velocities, which require correspondingly wider heater plates, the heat loss reaches the point where it is a major source of expense. Not only is a high heat loss objectionable and expensive because of the excessive energy required to maintain the heater strip at a proper temperature, but the heat which is lost must be removed from the room or building in which the machine is operating and this places a greatly increased load on the air conditioning equipment. In fact, with recently designed, high speed apparatus constructed according to the disclosure of the above mentioned application, the cost of energy for heating the heater strip and the cost of additional air conditioning constitute a major portion of the total expense of processing the yarn.

A second disadvantage of the earlier apparatus is that it provides no convenient means for varying the amount of tension imparted to the yarn by contact with the heater element. In certain instances it is extremely desirable that contact of the yarn with the heater strip impart an appreciable tension to the yarn while in other instances it is desirable that very little tension be imparted to the yarn by its contact with the heating element. As will readily be seen, a flat plate in contact with the yarn provides no means for readily varying the tension imparted to the yarn by its contact with the plate as long as the size of the plate remains constant.

Still another disadvantage of the earlier apparatus is that in some instances low denier yarns cannot be supplied to the heater strip under a low enough tension to permit adequate contact for the desired degree of heating without having the yarn under an excessively high tension at the time it contacts the senate edge. Accordice ing to the process of the above identified application, th tension in the yarn after passage about the acuate edge need only be about 0.2 gm. or less per denier and with yarns of very low denier, this results in a total tension of only a few grams. It is, therefore, necessary that such yarns be supplied to the heater element under a practically negligible tension since contact with the heating element will increase the tension of the yarn and if the tension is appreciable immediately preceding the point at which the yarn contacts the heater element, it becomes impossible to retain the tension in the yarn at the desired level following its contact with heater plate.

Still another disadvantage of the earlier apparatus is that it provides inadequate tension regulation in some instances and in particular when yarns of very low deniers are being processed. The difiiculties of supplying a yarn end under a very low but constant tension will be apparent to those skilled in the art and yet any variation in tension in the yarn being supplied results in large diiferences in the degree of elastization of the finished yarn. A non-uniformly elasticized yarn is not only objectionable because of its lower average degree of elasticity but also because it tends to result in woven or knitted goods having a non-uniform appearance.

It is a primary object of this invention to provide apparatus, suitable for processing yarn according to the method disclosed in US. application Serial No. 274,358, which overcomes the disadvantages of earlier apparatus.

It is another object of the invention to provide apparatus, useful in the production of elasticized yarns, which is extremely simple in design, which is inexpensive to manufacture and which is economical in operation.

It is still another object of the invention to provide improved methods for maintaining a running length of yarn under a substantially constant tension during such time that a processing operation is performed on the yarn.

The above as well as other objects of the invention are accomplished by the provision of apparatus which utilizes a heater element in the form of an elongated rod about and along which the yarn may be passed for a total of about /2 or more turns to thereby result in adequate contact and uniform heating. A. blade member is preferably secured generally transversely of the longitudinal axis of the rod heating element with its acuate edge positioned in close proximity to the surface of the rod so that a yarn end in contact with the heating element can be drawn into contact with the acuate edge without any appreciable drop in the temperature of the yarn. Preferably the apparatus also includes an overfeed, i.e., metering device for feeding a greater length of the yarn to the heater rod than is withdrawn from the acuate edge so that the yarn is allowed to contract while in contactwith the heater element.

Preferred embodiments of the invention will now be illustrated with reference to the accompanying drawings in which:

FIGURE 1 is a front plan view of one form of apparatus according to the invention showing two positions for independently processing two ends of yarn.

FIGURE 2 is a cross-sectional view of the apparatus of FIGURE 1 taken along line 2--2 in FIGURE 1.

FIGURE 3 is a schematic drawing of the gear arrangement for the overfeed device of FIGURE 1.

FIGURE 4 is a schematic drawing of the apparatus of FIGURE 1 illustrating the yarn ficw path and the electrical circuit for the heater element.

FIGURE 5 is an enlarged view in perspective of one of the bracket members which serves as a support for the blade member.

FIGURE 6 is an enlarged view of a modified form of heater rod.

With reference to FIGURES 1 to 5 of the drawings in greater detail, there is illustrated a support frame, generally indicated by the reference numeral 10, having a first horizontally extending support member 11 carrying a plurality of supply bobbins 12, to supply an end of yarn to each of the positions of the yarn elastrcizrng apparatus. An end of yarn 13 from each of the bobbins 12 is drawn through a guide member 14, positioned axially of the supply bobbin so that the yarn may be readily removed in an over-end manner, and is thereafter passed to a tensioning device, generally indicated by the reference numeral 15, which is secured to a frame member 16 by any suitable means. The tensioning device may be and preferably is a gate type tension regulating device such as disclosed in US. patent application Serial No. 469,430, filed November 17, 1954, now US. Fatent 2,790,611, since, as will subsequently be explained in detail, the use of an eflicient regulating device permits the apparatus to be employed with more different types of yarn; however, for most types of yarn, the tensioning device 15 may be of any conventional type since it ordinarily serves the sole purpose of pretensioning the yarn to a slight extent as it is fed to the elasticizing apparatus.

The reference numeral 17 generally indicates an overfeed arrangement which permits the yarn to contract a selected amount during the elasticizing procedure. The overfeed arrangement comprises a housing 18 having a support portion 19 secured to a frame member 20 by any suitable means such as by bolt 21. Extending through housing 18 and journaled in suitable bearings, not illustrated, is a rotatable shaft 22 and carried by the shaft 22 within housing 18 is a small spur gear 23. Gear 23 drives an idler gear 24 which in turn drives a larger gear 25 carried by a shaft 27 which also passes through housing 18 and extends outwardly on either side thereof. Gear 25 drives a small idler gear 28 which meshes with a spur gear 29 carried by a third shaft 30 which is journaled in the walls of housing 1 8 and extends from the housing on one side thereof. A cylindrical roll 31 having a smooth yarn engaging surface is secured to one end of shaft 27 and, in cooperation with a small roll 32 secured to shaft 39, serves to withdraw the yarn in a manner to be subsequently described. Roll 31 is of larger diameter than roll 32 but the gear ratio is such that the smaller roll is driven at a sufliciently higher number of revolutions per minute to give the rolls a substantially equal peripheral velocity. Mounted on shaft 27 on the opposite end to roll 31 is a yarn engaging over-feed roll 33 which rotates at the same r.p.m. as roll 31 but which preferably has a larger diameter than roll 31 to give it a higher peripheral velocity.

The housing 18 is provided with an upstanding triangular flange 34 which carries a pair of small pigtail guides indicated by the reference numerals 35 and 37. Extending into housing 18 through flange 34 is a motion transfer rod 38 which is operatively connected to a clutch, not illustrated, which makes it possible to disengage gear 23 from gear 24 for purposes of starting and stopping each individual position. Extending upwardly from housing 18 and carried thereby is a support arm 39 carrying a small idler pulley 40 which acts as a guide in a manner to be subsequently described.

From the above description of the overfeed mechanism, it will be apparent to those skilled in the art that this component of the apparatus can readily be constructed from the yarn feed device conventionally employed on an Atwood Model 10-13 twister frame sold by the Universal Winding Company. The only necessary modifications are a lengthening of shaft 27, the addition of overfeed pulley or roll 33 and the addition of pigtail guide 35. In fact, as will subsequently become apparent, the entire apparatus can readily be made by modification of an Atwood l0-B twister frame.

Carried by frame member 16 and extending generally transversely of the longitudinal axis thereof are a pair of support members 41, only one of which is illustrated.

Extending through suitable bores in support members 41 and insulated therefrom is a heater rod 42 having any suitable diameter, for example from to /2 inch, and which is preferably formed of an alloy, such as that sold under the name of Nichrome, having a relatively high electrical resistance. The heater rod 42 is illustrated as extending across only two positions but it can suitably be of such length as to traverse one entire side of a twister frame and its small area, as compared to that of a wide flat strip, results in a very low heat loss. A compression spring member 43 is mounted over one end of the resistance rod 42 and has one end positioned against frame member 41 and the opposite end against an electrically non-conducting washer member 44 made of any suitable material such as resin impregnated fabric. The spring 43 is compressed by a nut 45, bearing against washer 44, which is in threadwise engagement with the extremity of heater element 42. This arrangement serves to tension the heater rod 42 and permits it to expand upon being heated without allowing it to sag under the force of gravity.

One end of heater rod 42 is electrically connected through a suitable conductor 47 to a step-down transformer illustrated schematically and indicated by reference numeral 48. Transformer 48 should be designed to supply power to rod 42 at a voltage sufliciently low, for example below about 30 volts, that the rod does not provide a shock hazard. Transformer 48 is operatively connected by means of conductors 49 to a variable transformer 56 which in turn is connected to a suitable supply of electrical power through a switch 51 and conductors 52. The end of heater rod 42 opposite to that connected to transformer 48 may be electrically grounded, for example to frame member 41, if one terminal of the transformer 48 is likewise grounded, as illustrated at 53, to thereby complete the electrical circuit.

Carried by frame member 16 are a plurality of support brackets 60 and secured to each of the brackets 60 is a small plate 61 with a suitable bore '62 for the passage therethrough of the heater rod 42. Brackets 61 can suitably be made of any rigid material such as metal but plates 61 are preferably made of an electrically nonconducting material, such as a resin impregnated fabric, so as not to short circuit the heater rod by contact therewith. Extending from brackets 60, in each instance, is an elongated arm 63 having an arcuate insert 64 made of a wear resistant material such as porcelain (see FIG- URE 5 of the drawings). The arcuate insert 64 preferably has a radius of curvature which approximately corresponds to the periphery of heater rod 42 and is positioned closely adjacent thereto to guide a yarn end traveling from over-feed roll 33 into contact with the heater element. Also carried by brackets 60, in each instance, is a small support arm 65, carrying a guide pulley indicated by the reference numeral 67, and still another arm 68 which serves as a support for a flattened blade member 69 having an acuate edge positioned closely adjacent to the heater rod. The blade member 69 is preferably adjustably secured to arm 68 so that the distance of the acuate edge from the heater rod can be adjusted to give the most satisfactory results.

Means 76 is provided for collecting the yarn and is illustrated schematically in FIGURE 4 of the drawings as constituting a conventional ring and traveller arrangement. It will be understood, however, that any conventional yarn take-up device can be used and that it is not necessary that a device be employed which results in the yarn being twisted. In fact, in many instances twisting of the yarn is not desired and, of course, in such instances a ring and traveller take-up device should not be employed.

For edge-elasticizing, the apparatus can be threaded in two slightly different ways. For yarns which contract on heating, a yarn end from supply 12 is fed through guide 14 and tension regulating means 15 and. is there after passed to roll 33 of the overfeed device 17. The yarn end is wrapped approximately 1 /2 turns around feed roll 33 and is then passed to the arcuate insert in arm 63. The yarn is then wrapped /2 or more turns around heater rod 42 and is passed to the blade member 69 carried by the bracket member 60 positioned immediately to the right of the bracket member supporting the arm 63 over which the yarn is passed. (See FIGURE 4.) The brackets 60 should be so placed that the distance between the arm 63 on one bracket and the blade 69 on an adjacent bracket is at least sufiicient to result in the yarn being adequately heated without requiring a rod with an excessively large cross-section and should generally not be less than 1 or 2 inches. On the other hand, there is generally no advantage in making this distance greater than about 20 inches unless yarns of a very large size are being prowssed. The number of turns that the yarn is wrapped around the heater rod depends entirely upon the amount of tension that is to be imparted to the yarn by its contact with the heater element, as will subsequently be explained in greater detail.

When employing the yarn crimping aspect of the invention, the yarn is passed about the acuate edge of the blade 69 following its contact with the heater element and is then passed generally parallel to the heater element to the guide pulley 67 carried by the same bracket 60 that supports the arcuate inset over which the yarn is passed. The yarn end is then passed through guide 37 and wrapped a number of turns about rolls 31 and 32 which serve to withdraw the yarn at a constant rate with respect to the rate of feed. The yarn end is thereafter passed about pulley 40 to takeup means 70, and the temperature of the heater element is brought to a proper value by adjustment of transformer 50. The apparatus is then placed in operation.

The arrangement described in the preceding paragraph is suitable for use only with conventional, -i.e., drawn yarns, such as nylon, which contract on heating since as will be readily apparent to those skilled in the art, if the yarn does not contract on heating the overfeed arrangement will result in a surplus of yarn which will prevent the apparatus from operating properly. With yarns that do contract on heating, however, the overfeed arrangement provides excellent tension control. The tension in the yarn before it reaches the feed roll 33 will normally fluctuate because the resistance met in unwinding the yarn from the supply package will vary but these fluctuations will be eliminated by the overfeed roll and the only tension in the yarn immediately following its passage around the overfeed roll is present as a result of the contraction of the yarn under the influence of heat. Inasmuch as it has been found that the tension due to contraction of the yarn remains relatively constant even with slight variations in the temperature to which the yarn is heated, it will be seen that the ov-erfeed arrangement permits extremely low but uniform tensions which are outside the range ordinarily obtainable with conventional tension regulating devices.

Best results with the overfeed arrangement are generally achieved when the diameter of feed roll 33, as compared with the diameter of withdrawing roll 31, is such as to give the maximum overfeed which can be achieved without the yarn becoming slack. This permits the yarn to contract the maximum possible extent on the side thereof contacted by the edge 69 and it has been found that this results in a higher degree of elastization than can otherwise be achieved, although it will readily be seen that the yarn can be caused to undergo any desired degree of thermal contraction by the employment of this overfeed shrinking arrangement. If overfeediug the yarn results in it reaching the blade at an undesirably low tension, it is generally preferable that the tension in the yarn at this point be increased by increasing the number of turns with which the yarn is wrapped around the heater rod rather than by decreasing the degree of overfeed. Of

course, the degree that the yarn can be overfed Without becoming slack will vary with different types of yarn but almost any type of yarn can be accommodated by changing the size of the feed roll 33 and it. has been found that a range of rolls sufiicient to give an overfeed of from about l to 15% is generally adeq uate. For any selected type of yarn one can attempt to operate with the largest roll and if the yarn refuses to run, can gradually decrease the size of the roll until one is found that is satisfactory. As a guide, it has been found that with Du Pont nylon type 200 (polyhexamethylene adiparnide) yarns an overfeed of about 10.0% generally gives the best results.

In view of the above description of the overfeed arrangement, it will be seen that it is advantageous for use with any yarn which contracts on heating, since it not only permits the yarn to be fed to the heater element under a uniformly low tension so that the yarn is permitted to contract the maximum amount possible, but also permits the tension in the yarn as it passes over the acuate edge to be readily adjusted by increasing or decreasing the frictional contact of the yarn with the heater element. The arrangement is, however, particularly advantageous for use with yarns of very small denier, since the tension that must be maintained in these yarns for best results is extremely low even after contact of the yarn with the acuate edge and this makes an uniformly low tension in the yarn before it contacts the heater element, not only advantageous but absolutely necessary. By the overfeed arrangement, as described above, the tension in the yarn prior to its contact with the heater element can be too small to be accurately measured and yet can be retained at a very uniform value as is evident from the quality of the yarn produced.

With yarns that do not readily contract on heating, the positive yarn overfeed arrangement in which the yarn is positively metered to the heating zone at a rate in excess of that at which it is withdrawn is not generally advantageous although it can sometimes be employed by adjusting the rate of feed to exactly equal or to be slightly less than the rate of withdrawal. For use with this type of yarns, however, the apparatus is preferably threaded by passing the yarn end from tension regulator 15 through guide 35 and to the arcuate inset in arm 63, with the remainder of the yarn path the same as previously described. By this arrangement the tension in the yarn being fed to the heater element is controlled by the tension regulating means 15 rather than by the combination of positive feed and heat, and it will be apparent that the versatility of the apparatus is increased by equipping the same with eflicient tension regulating devices so that the apparatus can be employed without utilizing the positive feed device if so desired.

With reference to FIGURE 6 of the drawings, there is illustrated a modified form of heater rod 42' which may be substituted for the heater rod 42 in FIGURE 1 and which is designed to facilitate the threading-up operation. A guide arm 64' is positioned in close proximity to the periphery of the rod 42' to guide a yarn end into contact with the surface of the rod, and spaced a suitable distance from arm 64 is a blade member 69' having an acuate edge which is also placed in close proximity to the periphery of the heater rod. Carried by rod 42' intermediate arm 64' and blade 69 is a rotatable sleeve which is preferably of the split type so that it may be seated within a suitable peripheral groove in rod 42' with its outer surface flush with the surface of the heater rod. The sleeve 75 frictionally engages the heater rod 42 with sufficient force to prevent accidental rotation thereof but with insuificient force to prevent it from being rota-ted when desired. Extending in a substantially radial manner from sleeve 75 are a plurality of short pins 76 which have a polished surface suitable for engaging an end of yarn. In threading, it is not necessary that the yarn be passed by hand around the heater rod but rather the yarn en-d may be led from arm 64, placed about one of the pins 76 and thereafter led about blade member 69. To adjust the tension imparted to the yarn by its frictional contact with the heater rod 42, it is then only necessary to rotate sleeve 75 to thereby increase or decrease the total are through which the yarn end is in contact with the surface of the heater rod. It will be understood that contact of the yarn with pin 76- also tensions the same to some extent so that the yarn need be in contact with the heater rod through a smaller total are than in the embodiment first described in order for a given amount of tension to be imparted.

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

1. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated heater rod positioned in the yarn path, means providing an acuate edge positioned in close proximity to the periphery of said heater rod, and means to positively meter said yarn to the heating means at a rate which is constant with respect to the rate at which it is collected by said takeup means, whereby when an end of yarn is passed in contact with said rod and withdrawn over said acuate edge, the uniformity of the tension in the yarn as it passes in contact with the acuate edge can be efiected by the combined action of positively metering and heating the yarn, and the magnitude of the tension in the yarn as it passes in contact with said acuate edge can be readily regulated by changing the total are through which said yarn is in contact with the peripheral surface of said heater rod.

2. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated heater rod, guide means to guide said yarn into contact with said rod, a blade mem ber having an acuate edge extending generally transversely of the longitudinal axis of said rod, said blade member being so positioned that said acuate edge is in close proximity to the periphery of said rod at a point spaced from that at which the yarn is guided into contact with the rod by said guide means to thereby permit said yarn to be wrapped a total of at least about /2 turn about said rod and withdrawn over said acuate edge, means to positively meter said yarn into contact with said heater rod at a rate in excess of that at which it is collected by said takeup means, whereby the uniformity of the tension in the yarn as it passes in contact with the acuate edge is insured by the combined action of overfeeding the yarn and heating the same and the magnitude of the tension of the yarn as it passes in contact with the acuate edge may be readily regulated by changing the total are through which said yarn is in contact with the peripheral surface of said heater rod.

3. Apparatus according to claim 2 wherein said heater rod is of a generally cylindrical shape and has a diam eter of from about & to /2 inch.

4. Apparatus according to claim 2 including pre-tensioning means to place the yarn under tension as it is fed to the positive meter means.

5. Apparatus according to claim 4 wherein said pretensioning means comprises a gate type tension regulator.

6. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated heater rod positioned in the path of a yarn end being passed from said supply means to said takeup means, blade means having an acuate edge positioned in close proximity to the periphery of said heater rod, whereby when an end of yarn is passed in contact with said rod and withdrawn over said acuate edge, the tension in the yarn in contact with said edge can readily be varied by changing the number of turns of said yarn about said rod.

7. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated heater rod positioned in the path of a yarn end passing from said supply means to said takeup means, yarn guide means to guide said yarn end into contact with said heater rod, blade means having an acuate edge positioned in close proximity to the periphcry of said heater rod at a point spaced from said guide means, a rotatable sleeve positioned about said heater rod at a point intermediate said guide means and said blade means, said sleeve carrying at least one pin member, whereby when an end of yarn is passed in contact with the said rod and withdrawn over said acuate edge, said sleeve member can be rotated to cause said pin member to engage said yarn and vary the arc through which said yarn engages the peripheral surface of said heater rod.

8. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated heater rod, guide means to guide said yarn into contact with said rod, a blade member having an acuate edge extending generally transversely of the longitudinal axis of said rod, said blade member being so positioned that said acuate edge is in close proximity to the periphery of said heater rod at a point spaced from that at which the yarn is guidedinto contact with said heater rod by said guide means to thereby permit said yarn to be wrapped a total of at least about /2 turn about said rod and withdrawn over said acuate edge.

9. Apparatus according to claim 8 wherein said rod has a generally cylindrical shape and a diameter of about to /2 inch.

10. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, means to heat said yarn at one point in its linear path, means providing an acuate edge over which the heated yarn is drawn, and means to positively meter said yarn to the heating means at a rate in excess of that at which it is collected by said takeup means, whereby the combined action of the positive meter means and said heating means serves to uniformly tension the yarn.

11. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, means to heat said yarn at one point in its linear path, means providing an acuate edge, means for positively Withdrawing said yarn from said heating means over said acuate edge, means for positively metering said yarn to said heater means at a rate in excess of that at which it is withdrawn by the Withdrawing means, whereby the yarn is allowed to contract upon being heated and the tension in the yarn is maintained at a uniform level by the combined action of overfeeding the yarn and heating the same.

12. Apparatus for processing a running length of yarn comprising in combination a yarn supply means, a yarn takeup means, an elongated cylindrical heating rod, a first bracket means, said first bracket means carrying a support arm having an arcuate, abrasion resistant insert positioned in closed proximity to the periphery of said rod, said abrasion resistant insert having a curvature substantially corresponding to the curvature of the periphery of said rod so that a yarn end passed over said insert is guided into contact with said heater rod, a second bracket means carrying a blade member with an acuate edge positioned generally transversely of the longitudinal axis of said heater rod and in close proximity to the periphery of said rod at a point spaced along the longitudinal axis of said rod from that at which the yarn is guided into contact with the rod by said arcuate insert to thereby permit the yarn to be wrapped at least about /2 turn about said rod and withdrawn over said acuate edge, a first driven roll to positively meter the yarn into contact with said heater rod, a second driven roll to positively withdraw the yarn from said heater rod over said acuate edge at a rate less than that at which it is fed to said heater rod by said first roll, and pre-tensioning means to tension the yarn prior to its being passed to said first roll, whereby the uniiormity or" the tension in the yarn as it passes in contact with the acuate edge is insured by the combined action of overteeding the yarn and heating the same and the magnitude of the tension in the yarn as it passes in contact with the senate edge may be readily varied by changing the number of turns of said yarns about said heater rod.

13. Improved apparatus for heating and controlling the tension in a running length of yarn as it is passed under tension about a sharp edge of a blade member in an acutely angular path, said improved apparatus comprising, in combination, an elongated heater rod, guide means to guide an end of yarn into contact with said rod, and blade holding means for securing a blade member so that a sharp edge of said blade member extends generally transversely of the longitudinal axis of said rod and is positioned adjacent the periphery of said rod at a point spaced axially of said rod from that at which the yarn is operatively brought into contact with said red by said guide means.

14. Improved apparatus for controlling the tension in a running length of heat-contractible yarn as it is passed under tension to a yarn heater and immediately thereafter about a sharp edge of a blade member in an acutely angular path, said improved apparatus comprising, in combination, means to positively meter, at a selected linear rate, an end of said yarn to said yarn heater and means to positively withdraw, at a second selected linear rate that is less than said first rate, said end of yarn from said blade edge, whereby the rate of metering of said yarn to said heater and the rate of withdrawal of said yarn from said blade edge may, with respect to the temperature to which the yarn is heated, be correlated to provide, as a result of yarn contraction, a substantially constant tension in said yarn as it passes about said blade edge.

15. Improved apparatus for controlling the tension in a running length of heat-contractible yarn as it is passed under tension to a yarn heater and immediately thereafter about a sharp edge of a blade member in an acutely angular path, said improved apparatus comprising, in combination, a first yarn advancing means, including an over-feed roll, to deliver an end of yarn to said yarn heater, a second yarn advancing means, including at least one driven roll, to withdraw an end of yarn from said blade edge, and means to drive said over-feed roll and said second named roll such that the peripheral surface of said over-feed roll moves at a rate in excess of the rate of movement of the peripheral surface of said second named roll, whereby an end of yarn passing from said over-drive roll to said yarn heater and thereafter to said second named roll is permitted to contract under the influence of heat and can be maintained under a substantially constant tension as a result of contraction.

;16. Apparatus according to claim wherein said over-drive roll and said second named roll are secured to a single drive shaft and the circumference of said over- 1Q drive roll is from about 1 to 15% greater than the circumference of said second named roll.

17. An improved method for controlling the tension in a running length of a heat-contraotible yarn in an elasticizing operation which includes the steps of heating the yarn and immediately thereafter passing the hot yarn about a sharp edge of a blade member, said method comprising positively metering said yarn at a selected linear rate to the area in which it is heated and positively withdrawing said yarn from said area at a second selected linear rate which is less than the rate at which the yarn is metered to said area, the values for said first and second linear rates being such that the yarn in said area of heating is maintained, as a result of contraction, under a substantially constant tension.

18. A method according to claim 17 wherein the rate at which the yarn is metered to said area in which it is heated is about 1 to 15% greater than the rate at which the yarn is withdrawn from said area.

19. In a method for elasticizing a polyhexamethylene adipamide yarn having a potential contraction under the influence of heat of at least about 10%, said method including the steps of passing a running length of said yarn, under tension, in an acutely angular path about the sharp edge of a blade member and heating the yarn in a portion of the yarn path immediately preceding the portion of the yarn path in which said yarn passes about said edge, the improvement which comprises positively metering said yarn to the area of heating at a selected linear rate, and positively withdrawing said yarn from said area and about said edge at a linear rate less, but not more than about 10% less, than the rate at which it is fed to said area, whereby the yarn is retained under tension as it passes about said edge solely as a result of contraction.

20. A method for heat-treating nylon yarn which comprises positively metering a heat-contractible drawn nylon yarn through a processing zone at a first selected linear rate, positively metering said yarn from said processing zone at a second linear rate which is less than said first rate so as to provide a degree of overfeed less than that which causes said yarn to become slack when heated, dry heating said yarn by contacting said linearly progressing yarn with a conductive heating surface within said processing zone to a temperature to result in contraction of said yarn, and correlating the rate at which said yarn is metered to said zone, the rate at which said yarn is metered from said zone and the temperature to which said yarn is heated to thereby permit said yarn to contract at a low and uniform tension within said processing zone.

References Cited in the file of this patent UNITED STATES PATENTS 1,882,539 Anderson Oct. 11, ,1932 2,111,211 Finlayson et al. Mar. 15, 1938 2,204,603 Kline et al. June 18, 1940 2,345,032 Castricum Mar. 28, 1944 2,584,779 Averns et a1 Feb. 5, 19,52

Claims (1)

1. APPARATUS FOR PROCESSING A RUNNING LENGTH OF YARN COMPRISING IN COMBINATION A YARN SUPPLY MEANS, A YARN TAKEUP MEANS, AN ELONGATED HEATER ROD POSITIONED IN THE YARN PATH, MEANS PROVIDING AN ACUATE EDGE POSITIONED IN CLOSE PROXIMITY TO THE PERIPHERY OF SAID HEATER ROD, AND MEANS TO POSITIVELY METER SAID YARN TO THE HEATING MEANS AT A RATE WHICH IS CONSTANT WITH RESPECT TO THE RATE AT WHICH IT IS COLLECTED BY SAID TAKEUP MEANS, WHEREBY WHEN AN END OF YARN IS PASSED IN CONTACT WITH SAID ROD AND WITHDRAWN OVER SAID ACUATE EDGE, THE UNIFORMITY OF THE TENSION IN THE YARN AS IT PASSES IN CONTACT WITH THE ACTUATE EDGE CAN BE EFFECTED BY THE COMBINED ACTION OF POSITIVELY METERING AND HEATING THE YARN, AND THE MAGNITUDE OF THE TENSION IN THE YARN AS IT PASSES IN CONTACT WITH SAID ACUATE EDGE CAN BE READILY REGULATED BY CHANGING THE TOTAL ARC

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