US3041815A - Strand tensioning and metering apparatus - Google Patents

Description

July 3, 1962 N. E. KLEIN STRAND TENSIONING AND METERING APPARATUS 3 Sheets-Sheet 1 Filed May 23, 1956 v A m m w.

NORMAN E KLEIN BY MkflZZM ATTORNEY July 3, 1962 N. E. KLEIN STRAND TENSIONING AND METERING APPARATUS 3 Sheets-Sheet 2 Filed May 23, 1956 JNVENTOR.

. NORMAN E. KLEIN ATTo RNEY July 3, 1962 N. E. KLEIN STRAND TENSIONING AND METERING APPARATUS 3 Sheet 3 Filed May 25, 1956 A Y TA I;

VENTOR,

NORMAN KLEIN 572 b- BY M ORNEY United States Patent Ofi" 3,041,815. Patented July 3, 1962 3,641,815 STRAND TENSIGNING AND METERING ArPAnArUs Norman E. Klein, Pendleton, S.C., assignor to Bearing Millikan Research Corporation, Pendleton, S.C., a corporation of Delaware Filed May 23, 1956, Ser. No. 586,86 44 Claims. (Cl. 5758.3)

This invention relates to ply action twisters, and more particularly to new and improved equalizer strand tension control arrangements for such apparatus.

By way of a brief explanation of some of the terminology employed in this application, it may be noted that with the introduction of feed back control in the textile trade a conflict in terminology has arisen. In many instances tension devices in the textile trade are spoken of as tension controls when they actually do not more than add a fixed amount of tension or pull to a strand or in other cases provide a constant multiplier which merely amplifies the original tension value including all variations. To differentiate between devices or elements that have control and those that do not and still speak within the parlance of textile terminology the words dynamic and static have been respectively added to clarify this interpretation.

In copending applications of Norman E. Klein and Edward J. Wright, Serial Number 512,552, now US. Patent No. 2,914,903, and Klein, Serial Number 516,- 391, now US. Patent No. 2,961,82A, there are disclosed ply action twister arrangements for ply twisting two strands of yarn into a two ply yarn or cord, which employ a capstan array comprising a pair of canted capstans connected together for synchronous rotation about their respective axes through the medium of an idler gear which is also rotatively mounted about a central axis. A separate strand of yarn is fed to each of these two capstans, each yarn from a separate source of supply, with one of the strands being driven in ballooned relation about the source of supply for the other of the strands. The ballooned yarn strand serves to impart rotation to the capstan unit, and by bringing the two strands together at a Y-ply point beyond the two canted capstans and along the axis of rotation of the idler gear a highly advantageous plying action will take place, thereby forming a two ply cord which is continually pulled away from the ply point by a suitable means. These capstans serve very effectively to meter the yarn fiow of the two strands each at the same rate to the plying point and under wide variations of tension. It is, however, desirable that the tension in the two strands being plied be approximately equalized, particularly in the case of resilient or elastic material such as nylon, in order to avoid the formation of a yarn or cord which has unbalanced twist or corkscrew configuration, wherein tensile strength is impaired.

In the previous devices there is provision for both static initial adjustment and dynamic tension control of the ballooned strand; however, there is only provision for static tension adjustment of the inner strand, with no dynamic operational tension control to alleviate any operational tension variations, such as may occur in the inner strand for various reasons. While apparatus according to these applications function well for most purposes, even with moderate tension differentials existing between the two strands as they feed into the two metering capstans (due particularly to the yarn metering control function of the two metering capstans), tension differentials may sometimes occur which are suificiently large as to cause strand slippage on one or both of the capstans, with consequent uneven feeding of-the strands to the ply point during such periods, thereby causing undesirable plied cord variations and configurations. Not only may these differential tensions occur during normal running of the plying apparatus, but such particularly may occur during startirg and stopping of the apparatus due to the ballooning strand having a dynamic feed back tension control as well as a static control, while the inner strand has only a static control for the tension thereof.

It is, therefore, an object of this invention to provide an improved ply action capstan array having an inner strand dynamic feed-back tension control.

A further object is to provide an improved metering capstan array having an inner strand constant tension feedback control.

Still a further object of this invention is to provide an improved ply action metering capstan array having an inner strand dynamic feedback control which is speed responsive.

Another object of the invention is to provide an improved ply action apparatus having a feed back tension control for each of the outer ballooned strand and the inner strand.

A further object is to provide an improved ply action apparatus having a dynamic feed back control for each of the outer ballooning strand and the inner strand, both tension controls being responsive to the rate of rotation of the ballooned strand about the ply axis, whereby differential strand tension will be held to a minimum during normal running operation and during starting and stopping of the apparatus.

A still further object of the invention is to provide an improved ply action apparatus of the type wherein a false twist is inserted in the strands during a portion of the pre-plying operation and is taken out of the strand during plying thereof, which is so arranged as to permit the inner strand to be maintained under low tension at the point of twist insertion while being maintained under a torque-controlled higher tension as it proceeds thereafter to the ply point.

Still a further object of the invention is to provide an improved strand tension device particularly adaptable to ply action apparatus and employing a torque-brakecontrolled rotatable yarn engaging member and a separately rotatable yarn guide for maintaining tension on e a strand, the member and guide being each rotatable about a common axis.

A still further object is to provide an improved strand tension device, particularly adapted to ply action apparatus, in which two members are rotatable, one by direct action of one of two strands being plied and the other by intercoupling the two members through the second strand, with the second member having a controlled braking torque exerted thereon to thereby control the tension of the second strand.

Still other objects and many attendant advantages will become apparent from the following detailed description of the preferred and several other embodiments of various aspects of the invention, taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 illustrates schematically the general arrangement of a ply action apparatus incorporating the invention;

FIGURE 2 is a view in partial section of a metering and tensioning capstan arrangement according to the in vention and as illustrated generally in FIGURE 1;

FIGURE 3 is a fragmentary plan view of the arrangement of FIGURE 1, further illustrating the capstan arrangement;

FIGURE 4 is a plan View of the face magnet of FIG- URE 3;

FIGURE 5 is a partial diametral section view of a modified capstan arrangement according to the invention;

FIGURES 6 and 7 are section views taken on lines 66 and 77 of FIGURE FIGURE 8 is a perspective view of one of the gears of the embodiment of FIGURE 5;

FIGURE 9 is a fragmentary sectional view of a further capstan brake modification;

FIGURE 10 is a partial sectional view of still another modification according to one aspect of the invention;

FIGURES 11 and 12 are perspective and diametral section views of the cap end portion of the preferred embodiment of the wrap-around tensioning capstan;

FIGURE 13 is a perspective view of the outer end portion of a modified wrap-around tensioning capstan;

FIGURE 14 is a section view taken along line 14-14 of FIGURE 13; and

FIGURES l5 and 16 are plan and fragmentary side elevation views of a modified embodiment according to another aspect.

Briefly a preferred embodiment of the invention takes the form of a pair of symmetrically arranged capstans having individual axis of rotation canted with respect to each other and with respect to a major axis of rotation common to both capstans, the capstans being arranged for meshed engagement with a common idler gear which is in turn rotatably mounted for free rotation about said major axis. Strands being plied are fed to a ply point in substantially synchronously metered relation by passing the strands in tractive engagement each with a separate one of the two metering capstans of an equalizer or metering capstan array. The outer ballooning strand first passes through an additive pre-tensioning device, then through a hollow spindle and in variable wraparound engagement with a wrap-around step dynamic balloon shape and tension control, after which it passes in a balloon about the supply package for the second or inner strand, and thence through a coupling or driving guide on the equalizer or meter-ing capstan array and in tractive engagement with one of the two metering capstans, from which it passes to the inverted Y-ply point. The inner strand proceeds from its supply package upwardly through a pre-tensioning arrangement (preferably of the pad or pinch-tensioning type) then through an axial bore in a rotatable wrap-around tension capstan (which functions on a torque control principle) concentrio with the plying axis, passing thence about and in variable wrap-around engagement with the peripheral surface of the Wrap-around capstan, then in tractive engagement with the other of the two metering capstans, from which it then progresses to the inverted Y-ply point. The rotatable wrap-around tension capstan is braked by suitable means (which in the preferred embodiment operates on a magnetic eddy current principle), causing the tension in the inner strand as it passes to the metering capstan to be controlled by the degree of wrap-around about the peripheral surface of said Wrap-around capstan; the degree of Wrap-around being in turn a function of the braking torque exerted on the wrap-around capstan by the magnetic brake and the difierence in the input tension of the inner strand as it passes thereto and the required inner strand output tension to yield a torque on the capstan of equal and opposite magnitude to the brake torque therein. In this preferred embodiment wherein a magnetic eddy current brake is utilized, the braking action (and thus the strand output tension) is dependent upon the speed of rotation of the capstan array, and the tension on the inner strandis dynamically controlled similarly to the outer ballooned strand, matching the action of the Wrap-around step dynamic tension and balloon shape control since this outer strand is governed by a similar speed-tension response characteristic. The net result is an improved ply action apparatus including substantially balanced dynamic tensioning means for both the inner and outer strands, with resultant minimizing of differential tensions in the two strands prior to their being plied. A further advantage resides in the fact that the inner strand tension may be maintained at a low value at the point of twist insertion (with resulant minimizing of broken ends in the inner strand) while controllably regulating the tension between this twist point and the ply point at such higher tension value as may be desired for matching the tension of the outer strand.

In addition to the preferred embodiment as briefly described above there are also disclosed several alternative embodiments and modifications of the invention, each of which will be described in detail in the following paragraphs.

Referring to FIGURE 1, a strand of a yarn A from an external source, such as supply package 11, is fed through adjustable tensioning assembly 13, thence axially through the center of hollow rotatably driven spindle shaft 15, through a radial opening in the shaft 15, then in wrap-around relation about wrap-around step tension balloon shape control 17 (of conventional construction), which forms a dynamic strand-tension responsive negative feed-back tension and balloon shape control device, such as shown for instance in the Klein and Wright application Serial No. 512,552, filed June 1, 1955, and in a semi-loop or balloon about the exterior surface of cylinr cal housing 19, and thence through a pigtail coupling guide 24: and in tractive Wrap-around relation about one capstan 73a in a symmetrical capstan array, generally designated 40, to a ply point with another strand B. Strand B is fed from an internal source of yarn disposed within the thus formed balloon (for example, from a yarn package 21 mounted within the cylindrical housing 19, which package and housing are restrained against rotation as by an off center Weight 22, as shown, or by magnetic action, etc.), through adjustable pre-tensioning assembly 23 (in the instant example a plurality of disctype tensioners 23a mounted in spaced apart relation on a shock-mounted plate 23b) and thence about a guide roller 24 and through an axial bore in an axially disposed torque wrap-around capstan 26 in the capstan array 49, thence in sliding frictional wrap-around relation about the end of the capstan 26, then in tractive wrap-around relation about the other rotatable capstan 79b of the array 40, and thereupon proceeding to the ply point of the two strands.

The plied yarn or cord AB is fed from the ply point by a constant speed driven feed roll arrangement 25, and thence on to a take-up bobbin 27 driven in any suitable manner, as by surface contact roll 29. The spindle shaft 1'5, feed roll arrangement 25 and surface drive roll 29 may be synchronously driven from either common or independent sources of power, as described and illustrated in the above mentioned co-pending application of Klein and Wright, and is, therefore, not shown herein.

Capstan array 49 is mounted on a supporting bracket 32 suitably secured at its base end 34 as by screws 35 to the upper end of cylindrical housing 19, and having formed at its upper end an adjustable internally threaded split clamping sleeve 36. Capstan array 49 comprises a housing 42, the lower end 44 of which is threaded for complementary engagement with threaded sleeve 36. The housing 42 is securely held in threaded engagement with the clamping sleeve 36 as by a bolt 38 extending through a pair of ears 39 formed on the sleeve 36, as more clearly seen in FIGURES 2 and 3.

Press fit into shouldered recesses in housing 42 are two low-friction bearings 46 and 48 (i.e. ball bearings or other suitable construction as may be desired) which support within the inner race thereof for free rotation therein a rotor shaft 56, the axis of rotation of which is aligned with the axis of rotation of spindle shaft 15 as illustrated in the instant embodiment. The lower end recess in the housing 42 is internally threaded below the lower end of bearing 48, as indicated by the numeral 50, for the reception of a complementary threaded ferromagnetic field adjustment ring 52. Field adjustment ring 52 has a plurality of radial air cooling holes 54 formed therein. The purpose of this ring 52 will be described in more detail as the desc.ption proceeds. The lower end of rotor shaft 56 is threaded and has a securing nut 58 secured thereto for preventing upward axial displace ment thereof. If desired, a set screw 59 may be employed to retain the nut 58 in secured relation on rotor shaft 56.

The upper end of rotor shaft 56 is enlarged to form a head 60 having a pair of opposed upwardly and inwardly inclined faces 61a and 61b, adjacent each of which is supported one of the strand metering capstans 70a and 70b. Each of capstans 70a and 70b is arranged for rotation about an axis perpendicular to the plane of its respective adjacent face 61a and 61b, and to this end stub shafts 62 are threadedly secured in a respective tapped bore in each of the faces 61a and 61b. Intermediate the ends of each of stub shafts 62 is a standoff collar 63 against one end of which is secured the inner race of a low friction bearing 64 held on the end of the stub shaft by a lock nut 66 threadedly secured on the free end of the shaft. The outer race of each of the bearings 64 is press fitted into the bore of respective capstans 70a and 70b, whereby each capstan is thus adapted for free rotation about its respective stub shaft 62. In the illustrated embodiment, capstans 70a and 70b have a single sharp-angled groove formed therein as indicated at 72, in order to provide maximum tractive action between the yarn strands A, B and their respective capstans 70a and 70b; however, this traction arrangement for the capstans may be modified as may be desired to fit the needs of any particular instance of use. Capstans 70a and 70b are coupled together for synchronous rotation about their respective canted axes through the medium of a rotatable idler face gear 80 in meshed relation with beveled gears 76 formed integral with, as illustrated, or connected to the adjacent end of each of the capstans 70a and 70b. To this end face gear 80 has a central shouldered recess which is press fitted over the outer race of a bearing 82, the retention of which is assisted by a snap ring 84 releasably fitted Within a shallow groove in the inner peripheral wall of the recess.

Rotor shaft 56 has an axial bore running therethrough, in the upper end of which is formed a counterbored shouldered recess 92 for press fitted reception of the outer race of a low friction ball bearing 94. The nut 58 at the lower end of rotor 56 has a skirt 96 formed thereon, the lower end of which skirt has a shouldered recess formed therein for press fitted reception of the outer race of another low friction ball bearing 98. Mounted for rotation in bearings 94 and 98, by press fit in the inner race of each of these bearings, is an inner rotatable torque shaft 100 having a central bore 102 formed therein. The upper end of torque shaft 100 has formed thereon or suitably secured thereon (as by a press fit as illustrated), for rotation therewith, a yarn guiding and torque transmitting wrap-around capstan 104 having a spiral end groove 106 formed therein for the guiding of strand B, as will become more readily apparent hereinafter. In the preferred example as illustrated in FIGURES 2 and 3, as well as FIGURES l1 and 12, the groove 106 takes the form of a single spiral groove and connects with the' bore 102 in torque shaft 100 through an enlarged 01f center aperture 105. The aperture 105 is so offset from the axis of axial capstan 26, including torque shaft 100 and capstan 104, as to form a yarn engaging surface such that the strand B passing therethrough will be substantially coaxial with the torque shaft 100. It will be apparent that this arrangement of the aperture 105 will not only serve to maintain the strand B in a dynamically balanced position as it proceeds through the torque shaft 100 and the center aperture 105 in the cap 104, but will also accomplish the highly advantageous function of substantially reducing, if not completely eliminating, strand contact with the inner surface of tube shaft as it passes therethrough. Dynamic balancing of end cap 104 may readily be accomplished in any suitable or desired manner, as by the forming of the off center aperture of suflicient size as to offset formation of groove 106, or by addition of balancing weight or the like, as may be desired.

The lower end of torque shaft 100 has secured thereto, as by a set screw 110, a metallic disc 108 which is preferably made of low magnetic reluctance material such as aluminum, etc. Supported in concentric relation beneath metallic disc 108 is a face magnet 112 having a plurality of circumferentially spaced, alternately north, south poles 114. Face magnet 112 may be sup ported in any suitable manner, as for example, by being secured through the medium of securing screws 118 to a support flange 116 which forms a part of support bracket 32. Conveniently, support flange 116 may also serve to support guide roll 24 for axial guiding of the strand to torque shaft 100.

In operation, strand A passes through spindle shaft 15, and then in variable surface contact with wrap around step 17, after which it passes in balloon form through guide 20 and in tractive engagement with capstan 70a, from which it proceeds to the ply point. The tension in this strand is preadjusted by adjustment of the adjustable static pre-tensioning array 13, in order to provide the desired balloon size range for the strand as it passes in balloon shape about the housing 19. The tension in the strand A as it proceeds through the balloon portion of its path is self-maintained by the variable wrap-around of the strand on wrap-around step 17 by interacting negative feed-back response between the step 17 and the balloon strand. As is well known in the art, the variation of wrap-around of the ballooning strand on wrap-around step 17 is a function of strand input and balloon tension, wind resistance to balloon movement and rate of rotation of the balloon, among other factors, and varies in such a manner by negative feed-back response as to tend to keep the tension constant in the strand A. Thus, an increase or decrease in balloon tension causes a smaller or larger wrap angle on the step 17, and this effects a negative feed-back control response between the strand and the step 17 in that a decreased or increased tension multiple is thereby applied to the strand by the step 17 as a function of the change in wrap angle, and this in turn tends to restore the balloon tension and size in a negative direction toward the desired value. This system of yarn tension control for strand A is quite advantageous as is well known in the art and serves to maintain a substantially constant tension in strand A during normal operation at one balloon velocity. However, as is also well known in the art, since the control exerted by this wrap-around step system is a function of balloon rotational velocity, variations of balloon velocity such as may occur for example during starting and stopping of the apparatus cause corresponding variations in the balloon tension of strand A. It is, therefore, extremely desirable that any dynamic tension control for the inner strand B maintain a tension control which is a function of the rate of rotation of the balloon A in as closely a similar manner to the speed responsive tension control exerted by the wrap-around step 17 as is possible.

To this end there is provided as a complementary adjunct to the wrap-around step tension control for strand A the axial wrap-around torque capstan 26 (including torque shaft 100, torque transmitting wrap-around cap 104, and disc 108, as described above), which serves in conjunction with face magnet 112 as a further dynamic strand-tension-responsive negative feed-back tension control device to maintain a normally constant output tension on the strand B as it proceeds from the cap 104 to the metering capstan 70b. The torque capstan assembly 26 functions in a negative feed-back responsive manner to maintain a desired tension level in the strand B closely analogous to the function of variable wrap angle step 17 for the strand A. Thus, if the output tension should decrease or increase by a slight or larger amount the drag exerted on the torque capstan assembly 26 will inherently effect a negative feed-back response between the strand B and the torque capstan assembly, which response takes the form of a corresponding increase or decrease, respectively, in wrap angle of the strand about the cap 104, to thereby restore the strand to the desired tension level.

As stated above, strand B proceeds from guide roller 24 axially through axial bore 102 in torque shaft 160 through groove 106 and cap 104, and then in wraparound relation about the circumferential peripheral surface of cap 104, from which it passes through and in tractive rolling frictional engagement with metering capstan 70b, after which it proceeds to the ply point. Upon rotation of the entire capstan array 40 through the action of balloon strand A as exerted on the capstan array through its engagement with coupling guide 20 and/or metering capstan 70a, the entire capstan array 40, in cluding the disc 108, will be rotated about its common or major axis, and drag torque will be exerted on torque transmitting wrap-around capstan 26 through the rotation of disc 108 in the magnetic field between face magnet 112 and field adjustment ring 52. The rotation of this disc 108 causes eddy currents to be set up therein proportional to the rate of cutting of the magnetic lines of force which in turn generate a magnetic field of proportional intensity which reacts with the field from magnets 114 to oppose the rotation of the disc 108, and thus the rotation of the entire torque capstan 26. The extent of eddy currents generated in the disc 108, and thus the extent of braking action exerted on the torque capstan 26 by the magnet 112 is therefore a function of the rate of rotation of the disc 108.

Since the torque capstan 26 (including disc 108) is coupled for rotation with the rotor 56 and capstans 76a, 70b, through the strand coupling between torque wraparound cap 104 and capstan 70b the rate of rotation of disc 108 will be substantially the same as the rate of rotation of the balloon of strand A, and thus the drag or brake torque exerted on torque capstan 26 will be a function of the rate of rotation of the balloon of strand A. In other words, the greater the speed of rotation of the balloon of strand A, the greater will be the braking action exerted by magnet 112 on wrap-around torque capstan 26, and vice versa. It will, therefore, be apparent that due to this braking torque, torque capstan 26 will tend to rotate retrogressively relative to (i.e. lag behind) the rotor shaft 56 and capstans 70a and 7tib, until a point of equilibrium is reached wherein the ten sion in strand B is such as to exert a rotative torque on cap 104 which is equal and opposite to the torque exerted on cap 104 through the braking action of magnet 112 and disc 108. By initially setting the pretensioning array 23 (see FIGURE 1) such that the tension in the strand B as it passes through the axial bore 102 is below the desired operating tension of strand B as it passes into engagement with metering capstan 7%, the additional tension necessary to bring the strand B up to the desired tension value will be added by the tension multiplication action of the wrap-around torque cap 104 on the strand. As is well known, the passage of a strand in running frictional contact with a cylindrical or other similar surface such as that of torque wrap-around cap 104 results in a multiplication of the strand tension as an exponential function of the extent of wrap-around angle. Thus, in the case of the torque wrap-around cap 104, the strand B will wrap about the outer periphery thereof until the tension multiplication factor as a result of this wrap-around is suificient to yield an output tension in the strand B as'it passes from cap 104 to metering capstan 70b which will give a torque equal and opposite to that exerted by magnet 112 on disc 108. As stated above, the braking action of magnet 112 on disc 108 is a function of the rate of rotation of disc 108 (and thus for all practical purposes the rate of rotation of the balloon of strand A). For any one speed of rotation of disc 108 the brake action thereon by magnet 112 is sub stantially constant, and for all practical purposes may be said to be actually constant. Thus, for any one rate of rotation, the magnet 112 will exert a constant predetermined brake torque on disc 108 and the remaining portions of torque capstan 26, including torque wrap around cap 104, whereby the strand tension between torque wrap-around cap 104 and metering capstan 7017 will be maintained at a substantially constant predetermined tension value. It will be apparent that such minor or major input tension variations as may occur in the strand B as it passes through the axial bore 102 will result in correspondingly small or large rotations of torque capstan 26 relative to rotor 56 and metering capstan 7 0b sufiicient to increase or decrease the strand wrap-around angle on the periphery of torque wrap-around cap 104 and correspondingly increase or decrease the tension multiplication factor to thereby maintain torque equilibrium and corresponding substantially constant tension (during normal running operation) in strand B as it leaves cap 104.

The brake torque exerted on disc 108 of the torque capstan 26 may readily be varied for any particular rate of rotation of the disc 103 relative to the magnet 112 by increasing or decreasing the flux density of the magnetic field passing through disc 188. In the instant embodiment, this is facilely accomplished through the medium of axially adjustable field adjustment ring 52, which is threadedly secured in the lower threaded recess of housing 42. By manually rotating the housing 42, including field adjustment ring 52 secured thereto, the axial position of the housing 42 and ring 52 will be varied, and thereby the spacing between ring 52 and the pole faces 114 of magnet 112 will be varied with corresponding inverse variation of the magnetic field density in the air gap between pole faces 114 and the ferro-magnctic ring 52. It will readily be seen that the ring 52 serves as a low reluctance portion of the magnetic path between each of the adjacent north-south poles 114, and thus the variation of the air gap between the ring 52 and the poles 114 will correspondingly result in an inverse variation in the magnetic flux density in the air gap therebetween, in which air gap the disc 108 is positioned.

In order to prevent over-heating of the parts in the vicinity of the magnetic brake assembly, the field adjustment ring 52 has formed therein a plurality of radial openings 54 to permit the circulation of air thcrethrough in order to carry off a portion of the generated heat resulting from the eddy currents in disc 10%.

While the axial torque capstan 26 has been illustrated as an assembly of several separate parts, including disc 108, torque shaft and torque wrap-around cap 104, and such assembly is the most desirable from the standpoint of ease of construction and assembly, it will be apparent that all or a part of this assembly might, if desired, be made as an integral unit.

In FIGURES 5-8 there is illustrated a modified embodiment according to the invention, which also incorporates a torque capstan assembly 226 having a torque brake which is a function of the rate of rotation of the balloon of strand A. In this embodiment, a mechanical slip clutch-brake arrangement is utilized to maintain a desired brake torque betwen the torque capstan assembly 226 and the rotor shaft 256. This arrangement is similar in other respects to the arrangement of the first described embodiment, and will thus be described only in the differing details thereof.

Referring to FIGURE 5, the rotor shm 256 is mounted in bearings 246, 248 in a similar manner to the rotor shaft 56 of the previous embodiment, ad has secured thereto a retaining nut 258 having the lower ball bearing support for torque shaft 200 press fit into a recess in its lower end. Formed integral with nut 258, or press fit thereon (as illustrated), is a gear 262 which is engaged in meshed relation with a secoid gear 264 disposed laterally thereof and :rotatably about an axis parallel to the axis of torque shaft 200. The gear 264 has an axial tubular extension 265 which is press fit within the inner race of each of two spaced apart low friction ball bearings 268, 270 which in turn are press fit into upper and lower shouldered recesses in a lateral extension 244 of the capstan housing 242. Slidably mounted within an axial bore extending through gear 264 and its extension 265 is an axially adjustable shaft 266 which supports a third gear 274 in concentric relation with gear 264, through the medium of a ball bearing 276 the inner race of which is press fit onto the lower end of shaft 266 and the outer race of which is press fit into a recess in the lower end of gear 274. A retaining nut 278 serves to assure the retention of bearing 276 on shaft 266. The axial disposition of gear 274 relative to gear 264 is determined by the axial position of shaft 266, which position may readily be varied as desired through the medium of an adjustment nut 267 which engages the threaded upper end of shaft 266 and rides on the upper end of gear extension tube 265. The gear 274 meshes with a gear 272 which is press fit onto the lower end of torque shaft 200. The gear ratios of gears 262, 264, on the one hand and gears 272, 274 on the other, are preferably such that a low order differential (i.e. of the order of that provided by one or two teeth difference, or more if desired) exists therebetween.

The gears 264 and 274 are operatively coupled together through the medium of a plurality of friction blocks 284 of nylon or other suitable material. Blocks 284, as illustrated are rectangular in cross section and are loosely fitted within a corresponding pluraltiy of openings 280 formed in symmetrical spaced apart relation in gear 264 and extending parallel to the axis thereof. The openings 280 each have formed at their lower end a fulcrum lip 282. In the upper face of gear 274 there is formed an annular groove or recess 288 which is radially aligned with the plurality of openings 280, and in which the lower ends of friction blocks 284 ride as guided by the depending separating segments 269 between slot openings 280 (see FIGURES 6-8). Preferably each of the friction blocks 284 has a boss 286 formed at its lower end which serves, together with an annular retaining lip 290 which may be formed on the rim of groove 288, to prevent longitudinally upward movement of the blocks 284 out of groove 288. It will be noted that by axial adjustment of the gear 274 through the medium of shaft 266 and adjustment nut 267 the mass of the friction blocks 284 which lies below the fulcrum lip 282 may be varied as desired to create a desired mass unbalance of these blocks about the fulcrum points formed by their respective fulcrum lips 282.

In operation the rotor shaft 256 will be rotated about its axis in a similar manner to that of rotor shaft 56 of the previous embodiment as through the rotational action of ballooning strand A. Rotation of rotor shaft 256 causes corresponding rotation of gears 262 and 264. R- tation of gear 264 in turn tends to effect rotation of gears 272 and 274, together with torque wrap-around capstan 226, through the medium of resulting centrifugal action of friction blocks 284 which frictionally engage the outer peripheral surface of the annular groove 288 in gear 274. The torque transmitting action between rotor shaft 256 and torque wrap-around capstan 226 is thus a function of the dilferential centrifugal force exerted by the plurality of blocks 234 on the groove 288 of the gear 274, as well as being a function of the coefiicient of friction between the blocks 284 and the engaging surface of groove 288. The differential centrifugal force exerted by blocks 284 on the peripheral surface of groove 288 is in turn a function of the vertical position of the friction blocks relative to their respective fulcrum points, and the speed of rotation of rotor shaft 256. Thus the torque transmitted from shaft 256 to torque wrap-around capstan 226 is a function of the speed of rotation of rotor shaft 256 and the balloon of strand A. It will be seen, however, that due to the small differential ratio between gears 262, 264 and gears 272, 274, for equal rates of rotation of the rotor shaft 256 and torque wrap-around capstan 226 there will be only a small difierential velocity between the rate of rotation of gear 264 relative to gear 274. It is, therefore, only necessary, to dissipate a very small amount of power in the friction clutch arrangement between these two gears 264, 274 in order to transmit the desired torque from rotor shaft 256 to the torque wrap-around capstan 226, thus resulting in low heat lossand small consumption of power.

For any given speed of rotation of the balloon strand A (and thus the rotor shaft 256) the friction blocks 284 will exert a substantially constant predetermined centrifugal clutch-brake action on the gear 274 to thereby exert a corresponding predetermined substantially constant (for constant rotative speed of the capstan array) torque on the torque wrap-around capstan 226. The strand B proceeding from its wrap-around position on the periphery of torque wrap-around cap 204 exerts a counter-torque on cap 204, which is transmitted through torque shaft 200 to the gears 272, 274 and the brake-clutch arrangement between gear 274 and gear 264. The strand B will build up a suliicient wraparound angle on the periphery of torque wrap-around cap 204 to create an output tension in strand B as it proceedsto the metering capstan 270b sufficient to counter-balance the torque transmitted to the cap 204 by the gear and clutch- brake system 262, 264, 284, 272, 274. By varying the axial position of shaft 266 and thus the axial spacing between gears 274, 264, the effective centrifugal clutch-brake action may be selectively varied to produce a selected output tension in strand B for any particular rate of rotation of the balloon of strand A. It will be apparent, as stated above, that the centrifugal clutch-brake action on torque wrap around capstan 226 for any particular setting of the shaft 266 will be a function of the speed of rotation of the balloon of strand A, the clutch-braking action being greater at high speeds than at low speeds due to the increased difierential centrifugal force exerted by the blocks 284.

Thus it will be seen that the function of this arrangement as a Whole is similar to that of the first described embodiment in that a substantially constant torque is maintained on torque wrap-around capstan 226 for any particular rate of rotation of the balloon of strand A, with the brake torque on capstan 226 varying as a function of a rate of rotation of this balloon. It will be noted that the torque exerted on capstan 226 through the clutch-brake system is similarly drag or brake torque in the sense of resisting the torque exerted by the strand B on the torque wrap-around capstan 226 which latter torque may 'be viewed as tending to rotate the capstan 226 relative to rotor shaft 256, irrespective of whether the gear ratios are so arranged that the torque capstan tends to lead or lag the rotor shaft. This system is, therefore, also highly advantageous when used in conjunction with a wrap-around step tension balloon shape control such as that illustrated at 17 in FIGURE 1. However, it will 'be apparent that one obvious disadvantage of this system is the use of a mechanical gearing and frictional clutch arrangement for the purpose of obtaining a desired brake torque on the torque wraparound capstan, whereas the preceding described arrangement requires only a simple magnetic brake for this puipose. On the other hand, this second embodiment is in some ways more advantageous than the preceding embodiment in that there is less power consumed and less heating of the parts in the braking assembly.

In another modification as disclosed in FIGURE 9, there is also employed a friction clutch-brake arrangement which efiectively reduces the power required to maintain the desired brake torque on the torque shaft 300 of the torque wrap-around capstan. In this embodiment, the torque imparted to the torque shaft 3% by the friction clutch 'brake arrangement will be substantially constant for all operating speeds of the balloon strand A and of torque shaft 300.

In this embodiment, the rotor shaft end nut 358 has gear teeth formed on the periphery of the lower end thereof which engage with an idler gear 362 of a differential idler gear system 360 rotatably mounted on a shaft 370 which is suitably supported eccentrically of the axis of the torque shaft 300. Idler gear system 369 has a second gear 364 fixedly connected to or formed integral with gear 362; the differential ratio between the gears 362 and 364 or the idler gear system 360 being small (e.g. of the order of that provided by one or two teeth difference, or more if desired). Gear 364 meshes with gear 366 which is loosely mounted on the torque shaft 390 for rotation thereon. Torque shaft 300 has fixedly secured thereto in any suitable manner a friction disc 368 beneath the lower end of nut-gear 358 and in face-to-face relation with gear 366. Gear 366 is adjustably held in thrust engagement with the friction disc 368 through the medium of a thrust spring 372, thrust bearing 373, and thrust nut 374, the latter of which is threadedly mounted on the lower end of torque shaft 300. By axially adjusting the thrust nut 374 the thrust exerted by gear 366 on friction disc 368 may be varied as desired to effect the desired torque transmission between gear 366 an disc 368. This will effectively determine the brake torque exerted on torque shaft 300 for any rotative speed of rotor shaft 356, and will thereby yield a substantially constant output tension in the strand B passing through the bore in torque shaft 309 as it leaves the wrap-around cap (not shown) connected thereto.

Due to the extremely fine degree of tension control which may be obtained on the strands A and B with the combination system according to this invention, particularly the system employing a similar dynamic tension control for both the inner and outer strands, it may be desired in some instances .to simplify the plying apparatus by elimination of the metering capstans, although for most practical purposes it will be found extremely advantageous to employ an arrangement utilizing such metering capstans. In FIGURE 10, there is shown schematically a simplified arrangement wherein a pair of simple pigtail guides are substituted for the metering capstans. 456 is rotatably mounted on a suitable support 432 through the medium of one or more low friction bearings 448. Torque capstan 426 is suitably rotatably mounted in low friction bearings 494 and 498 which are press fit in spaced apart relation in shouldered end recesses in the axial bore of rotor 456. Torque capstan 426 has an eddy current disc fixedly secured to its lower end, a portion of which is disposed in the air gap of one or more magnets 412. An axial bore 462 is formed in torque capstan 426 which suitably connects with a spiral groove 406 formed at or near the upper end of the torque capstan.

Secured in symmetrical spaced apart relation on the upper end of rotor 456 are two guides 476a and 47% (which may suitably be of the pigtail type for ease of thread-up, if desired) which serve to guide the strands A and B, respectively, to the ply point.

The operation of this embodiment is similar to that of FIGURE 1 except for the elimination of the strand metering function of the metering capstans, which are omitted in this embodiment. Further description of the operation of this embodiment is therefore not made, since such will be apparent from the foregoing description in connection with FIGURE 1. However, it will be noted as stated above that in this embodiment the formation of a satis- In this arrangement, the axially bored rotor factory plied cord or yarn, etc, will be substantially dependent on the maintenance of very low, if not substantially zero, differential tension bebtween the two strands A and B as they proceed to the ply point. This is accomplished through the matched characteristics of the wraparound step tension control for the outer strand A and the speed responsively braked torque wray-around capstan for maintaining tension on the inner strand B.

In FIGURES 13 and 14 there is disclosed an alternate embodiment of the torque wrap-around cap. In this embodiment the torque metering cap 104a has a symmetrical spiral groove 106a formed in its upper end in a substantially S-shape. This groove 106a obviously might also be formed in a reverse S-shape, as might the groove 106 be reversed, if desired, in the event that the arrangement or rotational direction of the parts is such as to cause the wrap-around of strand B in the opposite direction to that for which the illustrated capstans are designed. It will also be apparent that the groove may in some instances be radial, etc., or may take the form of a transverse port in the side of the Wrap-around cap and connecting the axial bore 102 of torque shaft with the wrap-around periphery of the wrap-around cap.

The center of groove 136a connects with the axial bore 195:: formed therein and which is arranged for alignment with the bore 102 of the torque shaft 100. This cap 194:: has the advantage of ease of dynamic balance due to its symmetrical groove 106a; however, due to the bore 165a being axial rather than off center as in the embodiment of FIGURES 1, 10 and 11, etc., it will be apparent that this arrangement will not in itself guide the strand B through bore 105:: precisely coaxially since the surface of bore 16511 is necessarily displaced from the axis of cap 164a by a distance equal to the radius of the bore. It will be desirable, however, in many cases to form the bore 105:: of slightly smaller diameter than the bore through the torque shaft 100 in order to more nearly center the strand, and particularly in order to guide the strand along a line out of contact with the interior of bore 192. It will be seen that in operation the strand B may be guided through either path of the double spiral groove 106a in the course of its passage from bore 105a to the circumferential periphery of the cap.

Referring to FIGURES 15 and 16, there is shown a further modification for increasing the eifective traction on the strand B (or both strands if desired) as it passes over its metering capstan, and which may suitably be employed with any of the embodiments except that of FIG- URE 10. In this modification the strand metering capstan 5701) has formed thereon a pair of grooves 572k in lieu of the single groove disclosed in the preceding embodiments in order to provide an increased angle of tractive engagement between the strand B and the metering capstan 57Gb to insure against possibility of slippage thereon. In order to provide for guidance of the strand from the peripheral surface of cap 594 to the first groove 57217 and to provide for intra groove transfer of the strand B between the two grooves 57% the strand guide finger plate 575 is fixedly mounted on the head upper end of rotor shaft 556, as through an Allen cap screw 576.

The finger plate 575 has an intermediate wide smooth strand guiding surface 577 formed thereon which serves to guide the strand as it proceeds from the periphery of cap 584 to the first or inner groove 5721;. The strand guiding surface 577 tapers to a terminal yarn engaging finger 578 which lies above and between the two grooves 57%, and serves to guide the strand in intra groove cross-over after the strand has passed almost completely around the inner groove 572b and during its transfer to the second or outer groove on the metering capstan 57Gb. After passage around the second groove the strand B then proceeds in the usual manner to the ply point.

While only mechanical and magnetic brakes have been illustrated, and such are preferred for various reasons as described herein, it will be apparent that other suitable brakes such as the viscous fluid type might be utilized if desired. For example, in FIGURE 1 a fluid or air and paddle wheel assembly might be substituted for the magnet and disc arrangement; while in FIGURE 5 a similar or other viscous fluid brake might be substituted for the centrifugally operable mechanical friction brake. Also, in connection with the use of brakes of the magnetic type, electromagnetic or hybrid electromagnetic-permanent magnet types of brakes might be utilized, if desired, in lieu of the permanent magnet type brakes illustrated, such being particularly useful in permitting adjustment of the inner strand tension through electromagnetic brake torque control during full operation of the apparatus.

It will be understood that although the preferred and most highly advantageous arrangement embodying the rotatably driven torque wrap-around capstan tension device is that illustrated wherein two strands are plied together, with one of the strands being tensioned by this device and the other ballooned strand being employed as a power source for actuating the device, this aspect per se of the invention readily lends itself to other embodiments and uses, both separately and in other combinations.

It will be further understood that relative terminology, such as above, below, lower, upper, inverted, etc., is used in the specification and/or claims solely for describing the relationship of certain elements with re spect to other elements when the apparatus is in its normal upright position and should not be construed as limiting the elements of the invention of this precise position.

While I have shown several embodiments of the various aspects of this invention, it will readily be apparent to one skilled in the art that many other embodiments and modifications are possible within the scope and spirit of the invention. It is, therefore, to be understood that the invention is not to be limited by the specific embodiments herein illustrated, but only by the scope of the appended claims.

I claim:

1. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic strand-tension-responsive negative-feed-back tension control means for a first strand being plied, and second dynamic strand-tension-responsive negative-feed-back tension control means for a second strand being plied, each of said tension control means being substantially mutually independent of one another and being negative-feed-back responsive to the tension in its respectively tensioned strand to vary its tension compensating eifect on said respective strand in an amount inversely proportional to the tension in said respective strand.

2. Ply action apparatus according to claim 1 wherein said first tension control means has operatively associated therewith means for driving said first strand in a balloon about a portion of the path of said second strand.

3. Ply action apparatus according to claim 1 wherein each of said tension control means has a substantially similar tension control characteristic.

4. Ply action apparatus according to claim 3 wherein said tension control characteristic for each of said tension control means is a function of plying rate.

5. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied, said second tension control means comprises a rotatable capstan, torque brake means operatively connected to said capstan, and means for guiding said second strand into sliding frictional variable wraparound engagement with said capstan, the wraparound angle being a function of the tension in said second strand and the braking torque exerted on said capstan by said torque brake means.

6. Ply action apparatus according to claim 5 wherein means are provided for driving said first strand in ballooned relation about a portion of the path of said second strand, said first tension control means comprising a wraparound step, and means for rotating said wraparound step.

7. Ply action apparatus according to claim 1, further comprising strand metering means for metering each of the strands as it proceeds in its path during plying.

8. Ply action apparatus according to claim 1 wherein one of said strands is fed in a balloon about the other strand, each of said tension control means having a tension control characteristic which is a function of the rotational velocity of said balloon.

9. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating eflect on said respective strand, one of said tension control means including a centrifugally operable brake, a rotatable strand engaging member, and a step-down drive connection between said strand engaging member and said centrifugally operable brake.

10. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating effect on said respective strand, one of said tension control means including a magnetic brake having a disc rotor and a stator, and a strand engaging member rotatable in synchronism with said rotor.

11. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating effect on said respective strand, said second tension control means including a rotatable strand engaging capstan, and including a torque brake operatively connected to said capstan.

12. Ply action apparatus according to claim 11 wherein said capstan has an axial strand guiding bore therein and a transversely extending strand guiding surface formed thereon and disposed between said bore and the periphery of said capstan.

13. A strand tension device comprising a pair of members rotatably mounted in concentric relation about a common axis, said members being also rotatable relative to one another about said common axis, strand guide means on one of said members resistive to torque exerted by a strand in one direction about said axis, and strand guide means on the other of said members resistive to torque exerted thereon by a strand in the opposite direction about said axis.

14. A strand tension device comprising a pair of members rotatably mounted in concentric relation one within the other, said members being also rotatable relative to one another about their common axis, strand guide means on one of said members resistive to torque exerted by a strand in one direction about said axis, and strand guide means on the other of said members resistive to torque exerted thereon by a strand in the opposite direction about said axis.

15. A strand tension device according to claim 14, the inner of said concentric members having an axial strand guiding hole therein.

16. A strand tension device according to claim 15, wherein one of said guide means includes a transverse slot at one end of said inner member.

17. A strand tension device according to claim 16 wherein said slot has a spiral configuration.

18. A strand tension device according to claim 14 wherein the inner of said concentric members extends axially beyond the outer of said members, said inner member having an axial strand guiding hole formed therein and extending therethrough at least partially in an axial direction.

19. A strand tension device according to claim 18 wherein the extended end of said inner member forms a cylindrical yarn engaging step, said guide means on the outer of said members having a strand guiding surface disposed axially inwardly from the end of said cylindrical step so as to cause a strand fed from the extended end and about said guide means on said inner member to tend to be wrapped about said step upon relative rotation of said members.

20. A strand tension device according to claim 14 wherein there is provided brake means adapted to resist rotation of one of said members.

21. A strand tension device according to claim 14 wherein there is provided brake means operatively connected to one of said members and adapted to resist rotation thereof.

22. A strand tension device according to claim 21 wherein said brake means comprises a magnet coupled to the inner of said members through magnetic induction.

23. A strand tension device according to claim 22 wherein said brake is an eddy current magnetic brake.

24. A strand tension device according to claim 14 wherein there is provided brake means operatively connected to the inner of said members and adapted to resist rotation thereof, said brake means comprising a friction brake.

25. A strand tension device according to claim 24 wherein said friction brake forms an operative connection between said members.

26. A strand tension device according to claim 25 wherein said operative connection comprises a difierential gear ratio system and a friction clutch-brake operatively connecting said members.

27. A strand tension device according to claim 14 and including a centrifugally operable brake operatively connected to one of said members.

28. A strand tension device according to claim 14 wherein there is provided brake means operatively connected to the inner of said members and adapted to resist rotation thereof, said operative connection comprising a differential drive ratio system.

29. A strand tension device comprising a member rotatably mounted for continuous rotating movement about an axis, strand engaging means on the peripheral surface of said member, a portion of the said engaging surface of said strand engaging means extending in a direction transverse to said axis for guiding a strand and positively transmitting a torque from said strand to said member in a first rotative direction about said axis, torque drag means comprising a substantially constant torque brake adapted to impart a substantially constant drag torque to said member in a direction opposite to said strand-exerted torque, and means additional to said strand adapted to impart rotation to said member.

30. A strand tension device according to claim 29 wherein said constant torque brake is selectively adjustable.

31. A strand tension device according to claim 29 wherein said additional means comprises guide means separate from said member and adapted to guide said strand and a second strand in rotatively intercoupled relation about said axis.

32. A strand tension device comprising a member rotatably mounted for movement about an axis, strand engaging means on the peripheral surface of said member, a portion of the said engaging surface of said strand engaging means extending in a direction transverse to said axis for guiding a strand and positively transmitting a torque from said strand to said member in a first rotative direction about said axis, torque drag means comprising a substantially constant torque brake adapted to impart a substanially constant drag torque to said memher in a direction opposite to said strand-exerted torque, and means additional to said strand adapted to impart rotation to said member, said additional means comprises a second strand, and guide means separate from said member for each of said strands and intercoupling the rotative movement about said axis of said first mentioned strand with said second strand.

33. A strand tension device according to claim 29 wherein said brake is a hysteresis magnet brake having a rotatable element and a normally stationary element, said rotatable element being rotatable in synchronism with said first mentioned member.

34. A strand tension device comprising a member rotatably mounted for movement about an axis, strand engaging means on the peripheral surface of said member, a portion of the said engaging surface of said strand engaging means extending in a direction transverse to said axis for guiding a strand and positively transmitting a torque from said strand to said member in a first rotative direction about said axis, torque drag means comprising a substantially constant torque brake adapted to impart a substantially constant drag torque to said member in a direction opposite to said strand-exerted torque, and means additional to said strand adapted to impart rotation to said member, said magnetic brake comprises two relatively movable component members including a magnet and a metallic disc member concentric with said axis, one of said component members of said brake being mounted for rotation with said first mentioned member.

35. A strand tension device comprising a member having an end peripheral surface and a radially outer peripheral surface and being mounted for rotation about an axis; rotation-resisting torque means arranged for operative connection to said member to apply a rotation resisting torque to said member; a substantially axially disposed strand guide; said member having a strand engaging means having a strand engaging torque transmitting surface transverse to said axis and operatively connected through said member to said rotation-resisting torque means, for guiding a strand between said axially disposed guide and the radially outer peripheral surface of said member; and strand guide means disposed in spaced-apart relation to said member and transversely spaced from said axis, said last named strand guide means being mounted for rotation about said axis.

36. A strand tension device according to claim 35 wherein said last named strand guide means comprises a rotatable capstan, and support means for said capstan, said support means being rotatable about said axis.

37. A strand tension device according to claim 36 wherein there is further provided a second capstan mounted on said support means for guiding a second strand, said capstans being adapted to rotate in synchronous relation about secondary axes separate from said first mentioned axis.

38. A strand tension device according to claim 37 wherein one of said capstans has a double annular groove formed thereon, and intra-groove guide means separate from said one capstan for guiding a strand from one to the other of said grooves.

39. A strand tension device according to claim 35 wherein said member has an axially extending hole formed therein, the bounding surfa.-e of said hole forming said axially disposed guide.

40. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to 2. ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating efifect on said respective strand, one of said tension control means including a centrifugal brake having a rotor and a stator, and a strand engaging member rotatable in synchronism with said rotor.

41. Ply action apparatus according to claim 40 further comprising a step-down drive connection between said strand engaging member and said rotor.

42. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating effect on said respective strand, one

18 of said tension control means including a magnetic brake having a rotor and a stator, and a strand engaging member rotatable in synchronisrn with said rotor.

43. Ply action apparatus for plying together two or more strands, comprising a rotatable strand guiding means for guiding each of the strands to a ply point, first dynamic feed back tension control means for a first strand being plied, and second dynamic feed back tension control means for a second strand being plied each of said tension control means being substantially mutually independent of one another and being responsive to the tension in its respectively tensioned strand to vary its tension compensating effect on said respective strand, one of said tension control means including a brake having a rotor and a stator, and a strand engaging member rotatable in synchronous with said rotor.

44. Ply action apparatus according to claim 43 further comprising a step-down drive connection between said strand engaging member and said rotor.

References Cited in the file of this patent UNITED STATES PATENTS 2,689,449 Clarkson Sept. 21, 1954 2,732,680 Vibber Jan. 31, 1956 2,7 6,160 Vibber Feb. 28, 1956 2,753,679 Von Schmoller et a1. July 10, 1956 2,869,313 Vibber Jan. 20, 1959 FOREIGN PATENTS 523,245 Belgium Oct. 31, 1953

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