US2814925A

US2814925A - Twisting and plying spindle balloon control

Info

Publication number: US2814925A
Application number: US450358A
Authority: US
Inventors: Alfred W Vibber
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-08-17
Filing date: 1954-08-17
Publication date: 1957-12-03
Anticipated expiration: 1974-12-03

Description

Dec. 3, 1957 A. w. VIBBER 2,814,925

TWISTING AND PLYING SPINDLE BALLOON CONTROL Filed Aug. 17, 1954 2 Sheets-Sheet l INVENTOR.

Dec. 3, 1957 A. w. VIBBER 2,814,925

TWISTING AND FLYING SPINDLE BALLOON CONTROL Filed Aug. 17, 1954 2 Sheets-Sheet 2 IN V EN TOR.

Wall/14L,

United States Patent O i TWISTING AND PLYING SPINDLE BALLOON CONTROL Alfred W. Vibber, Ridgewood, N. J;

Application August 17, 1954, Serial No. 450,358

21 Claims. (Cl. 57-583) This invention relates to the control of the balloon or free-flying loop of elongated flexible material present at balloon creating and maintaining twisting and/or plying mechanisms. The invention particularly relates to the control of balloons of spindles of the type wherein the material in the balloon is drawn from the balloon into the rotating shaft or flyer which creates and maintains the balloon. Such type of elongated flexible material treating spindle is herein designated an infeeding twisting and/ or plying spindle.

This application is :a continuation-in-part of application Serial No. 361,999, filed June 16, 1953, now Patent No. 2,736,160.

There are shown and described herein two species of the apparatus, as follows: (1) Figs, 1 and 2; and (2) Fig. 3 Both embodiments are of the one-spindle twisting and plying system generally of the type shown in Clarkson Patent No. 2,503,242, in which two strands are twisted together so as to form a two-ply strand, a first strand delivered from a supply thereof being ballooned about a let-off strand package from which the second strand is led.

The present invention represents an improvement over that described in my prior application Serial No. 361,999, particularly Figs. 11 and 12 of such prior application, wherein both the first and second strands are fed by synchronized positively driven feeding means. In the embodiment referred to in my prior application, the tension in the balloon is controlled by a means engaging the balloon and detecting changes in the shape thereof and means responsive thereto to adjust the height of the balloon guiding eye above the flyer. The present invention provides a simplified means responsive to changes in the shape of the balloon to vary the tension of the strand issuing from the balloon and approaching the plying junction, whereby the rates of absorption of the two strands into the plied strand may be controlled. As a result, when the balloon becomes too large, the tension in the first strand, issuing therefrom, and approaching the plying junction is decreased, thereby to increase the rate of absorption of the first strand, and when the balloon becomes too small, the tension in the first strand issuing therefrom and approaching the plying junction is increased, thereby to decrease its rate of absorption. The balloon is thus maintained within a predetermined desired range of diameter :as well as degree of wrap-around at the spindle.

The present invention has among its objects the provision of an improved simplified control for the balloon of twisting and plying mechanism.

A further object of the invention resides in the provision of a control for balloons of twisting and plying spindles of the infeeding type, such control being characterized by its simplicity of construction and maintenance, by the fact that it is Wholly supported by the balloon generating shaft, and by the fact that the cont-r01 is wholly mechanical in nature.

2,814,925 Patented Dec. 3, 1957 ICE A still further object of the invention lies in the pro vision of automatic strand tension control means, wholly supported by the twisting and plying shaft of the spindle, for the strand leaving the balloon and approaching the plying junction of apparatus wherein a first strand is ballooned about a source of supply of a second strand to ply the two strands together.

The above and further objects relating to economies of use and manufacture will be more readily apparent upon consideration of the following specification.-

My invention is clearly defined in the appended claims. Where parts are, for clarity and convenience, referred to on the basis of their oriented position shown in the accompanying drawing, no limitation as to positioning of the entire structure is to be implied, since it will be understood that the entire structure may be inverted or that it may be used in any inclined position. Also in both the description and the claims, parts at times may be identified by specific names for clarity and convenience, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention isillustrated in the accompanying drawing forming part of this specification, in which: i

Fig. 1 is a somewhat schematic view, partially in side elevation and partially in vertical section, of a first embodiment of a one-spindle strand plying mechanism in accordance with the invention.

Fig. 2 is a view in horizontal section through the flyer of the spindle of Fig. l, the section being taken along the line 22 in Fig. 1.

Fig. 3 is a view in horizontal section through the flyer of the spindle of the second embodiment of the invention, the section being taken in a manner similar to that of Fig. 2.

In the system shown in Figs. 1 and 2, the first strand, designated 10, proceeds from the first let-off package 11 downwardly through positively driven strand feeding means 12 driven in synch-ronism with the spindle shaft 14, in a manner to be described, into the balloon 15 created by the flyer 16, which constitutes an enlarged head on shaft 14. The strand 10 is drawn in through the flyer and meets the second strand 17 fed from the second letoff package 19 at the point P on the axis of the flyer, the two strands being plied together at point P so as to emerge as the plied strand or cord 20. The cord 20 is taken up by a conventional take-up mechanism 21, preferably ,one such as shown in Clarkson Patent No. 2,503,242, which withdraws the cord and winds it on bobbin 22 under constant tension.

Taking up now the instrumentalities which operate upon the strand 10 in succession, the first let-off package 11 is preferably rotatably mounted on a support diagrammatically shown in Fig. 1 so as to present the strand 10 opposite the feed-oif eye into the strand feeding capstan system 12. Means 12 is made up of a first multi-grooved capstan 25 and a second multi-grooved capstan .26 spaced therefrom, the two capstans being positively geared together so as to rotate at the same speed and in the same direction by means of a gear 27-on capstan 25, a gear 29 on capstan 26, and the intermediate idle gear 3.0 meshing with the gears on the capstans, all of such mechanism being carried on fixed framework (not shown). Means 12, which serves to deliver the strand 10 to the balloon at essentially constant speed, is positively driven in synchronism with spindle shaft 14 by the worm 31 on the bottom of shaft 14, the worm gear 32 meshing therewith,

and mounted on shaft 34, the vertical shaft 35, and the upper horizontal shaft 36,

shafts

34, 35, and 36 being geared together, all at a 1 X 1 ratio, by bevel gears as shown, and shaft 36 being geared to capstan 26, also by bevel gears.

The fiyer 16 is in the nature of an enlarged head or flange on the top'of the rotatable shaft 14. Shaft 14 is mounted to rotate in bearings 37 in fixed frame parts 39 of the apparatus. The shaft 14 has its outer surface 40 between frame parts 39 crowned'to engage a driving belt (not shown), and serves as a means of creating and maintaining the balloon or free-flying loop 15 in the strand 10, of supporting the second let-off package 19 on top of the fiyer 16 in substantially non-rotating position, and of plying the two strands and 17 together at the plying point or junction P. Let-off package 19 is supported on a flange or platform member 41 positioned on the upper, hollow shaft 42, the lower end of shaft 42 being journalled in the fiyer 16 through themediurn .of the bearing 44. Platform 41 is eccentrically weighted at 45 so that, when the spindle shaft 14 is disposed at a small angle to the vertical the weight 45 will seek the lower position and thus maintain the package 19 and the shaft 42 substantially non-rotating even-though fiyer 16 rotates at high speed. For ease of illustration the spindle shaft 14- is shown disposed vertically.

Thershaft 42 serves also as a support for a means 46 for feeding the strand 17 from package 19 to the plying point P at essentially constant speed. Means 46 consists of a magnetic ball tension device 47 having a non-magnetic seat 49 positioned across the upper end ofthe shaft 42, the magnetic ball 50 fitting within. such seat, the strand 17 progressing between the ball and the seat down into the shaft 42. A magnet 51 positioned beneath seat member 49 maintains the ball 50 stably in its seat. After leaving the magnetic ball tension device, the strand '17 progresses into a radially outer groove on the idle upper multi-grooved feeding capstan 52 journalled horizontally in shaft 42, and thence proceeds downwardly to the confronting radially outer groove of the driven lower multi-grooved capstan 54. Strand 17 then travels from groove to groove between capstans 52 and 54 until it reaches a central groove in driven capstan 54 from which it then travels vertically downwardly to the plying point P.

Capstan 54,is driven in synchronism with the rotation of flyer 16 by means of the central hollow extension shaft 55 of the fiyer, shaft 55 carrying a worm 56 on its upper end. Worm 56 meshes with the hourglass worm gear 57 journalled horizontally within shaft 42 at a position radially displaced from the axis thereof. Worm gear 57 has on its outer ends the small pinions 59 which mesh with the larger pinions 60 on the ends of capstan 54. It will be apparent that rotation of the fiyer 16 and thus of the, shaft 55 relative to the shaft 42 will positively rotate the multi-grooved capstan 54. With the proper choice of sizes and hand of the worm 56 and the worm gear 57, and the proper relative sizes of pinions 59 and 60, the strand 17 will be fed downwardly to the plying point P at the same rate that strand 10 is fed into balloon 15.

The balloon in strand 10 is created and maintained by the balloon-generating-and-guiding axially concave pulley 61 positioned adjacent the outer end of the radial strand guiding passage 62 in the fiyer 16. As shown in Figs. 1 and 2, pulley 61 is mounted on a reciprocable supporting member 64 which is mounted in a bore 65 extending generally tangentially of the fiyer disc, and

which is urged in a clockwise direction with respect to.

the fiyer (Fig. 2) when the fiyer itself rotates clockwise, as indicated by the curved arrow in Fig. 2, by the coil compression .spring 66 acting between the closed bottom 67 of the bore 66 and the piston-like enlargement69 on the shank 70 of support 64. Support 64 is prevented from rotation with respect to the fiyer by the key 71 on its enlargement 69 which engages in the longitudinally extending groove 72 in the confronting side wall of bore 65. The pulley 61 is journalled on a vertical axis between the upper and lower arms 74 at the forward end of support 64, and can reciprocate from a forward position, with respect to the flyer, wherein the forward end of enlargement 69 on support 64 engages the bore-closing hollow internal nut 75, and in which the longitudinally central forward edge of pulley 61 extends markedly into passage 62, to one in which the longitudinally central forward edge of the pulley lies substantially flush with the rear wall of passage 62.

The pulley 61 constitutes the means whereby the fiyer 16 exerts force on the strand 10 at the lower end of the balloon to create and maintain such balloon. Consequently, the spring 66 must exert at all times a forward force on pulley 61 which equals the rearwardly directed force R on the pulley exerted thereon by the balloon. When the balloon (1) has a minimum diameter within the operative range, and thus a minimum wrap-around, the value of R is at a minimum. When the balloon (2) has amaximum diameter within the operative range, and thus a maximum wrap-around, the value of R is at a maximum. The spring 66 is so chosen that when the balloon is at condition (1) the enlargement 69 will haveretreated at least slightly from nut 75, that is, pulley 61 will have moved counterclockwise with respect to the fiyer, and that when the balloon is at condition (2) the pulley 61 will have retreated longitudinally appreciably further with respect to the flyer but not sufficiently to bring the longitudinally central forward edge portion of the pulley flush with the rear side wall of passage 62.

The pulley 61 thus constitutes a means for detecting changes in shape, that is, diameter and degree of wraparound, of the balloon 15. The apparatus of the present invention, in both, illustrative embodiments thereof, makes use of such changes in position of pulley 61 with respect to the fiyer to impose an added tension on strand 10 in the portion thereof which has left the balloon and is approaching plying junction P, such added tension being variable so that it is large when balloon 15 is at condition (1) and small when balloon 15 is at condition (2). .The added tension is generally additive to that existing in the portion of strand 10 in the balloon. The portion of strand 10 between the plying point and. the added tension imposing means, therefore, is subjected to the following total tension T at balloon condition (1):

' T (1) balloon (D'l added (1) andto the following total tension T at balloon condition (2):

i T (2) Tballoon (2)l' added (2 As we have seen,

balloon (2) T balloon (1) It is possible to make T at least substantially constant, and thus T =T by appropriate construction of the means which imposes the added tension on the strand. To promote greater stability to the system, however, it is preferred that the curve of total tension T versus balloon diameter be somewhat drooping, that is, that T decreases somewhat as balloon diameter increases. The reason for this will be apparent hereinafter.

In the embodiment of Figs. 1 and 2 the change of po' sition of pulley 61 relative to the fiyer 16 is employed to alter the degree of deviation from a straight line path of travel of the strand 10 through passage 62 by a snubbing abutment which is fixed relative to the fiyer, whereby to vary the added tension imposed on the strand. Tightly and nonrrotatably positioned in a vertical opening 76 in fiyer 16 is a rounded abutment member 77, which may be made of a hard substance such as Carboloy,

the member 77 having its rear surface extending markedly into the passage 62. Member 77 is so positioned that when pulley 61 is in its forward position the strand passes sinuously about member 77 and pulley 61, that when pulley 61 occupies a position corresponding to minimum operative balloon diameter (1) such sinuous path has become slightly straighter, and that when pulley 61 occupies a position corresponding to maximum operative balloon diameter (2) such sinuous path becomes so flattened that it approaches a straight line. The guide pulley 61, in conjunction with abutment 77, functions to impose a markedly larger retarding tension on strand 10 when the ballon is at its minimum operative diameter (1) than it does when the balloon is at its maximum operative diameter (2) because the greater sinuosity of the path of strand '70 at such first condition causes the abutment 77 to impose a greater force on the strand transverse to its path of travel.

If the described means for imposing an added retarding tension on the strand 10 were not employed, the greater tension in the strand in the balloon as the balloon expands, plus the greater friction imposed on it as it contacts the outer rear edge of the radial passage in the flyer due to the increased wrap-around of the balloon, would cause the strand 1G to approach the plying point under increased tension. Under such condition strand 1d acts as core at the plying point, and more of strand I67 than strand lid is absorbed into the plied strand or cord 20. Thus the balloon tends to continue to expand, since such prior apparatus is not self-compensating, until it becomes so large as to strike adjoining structures and thus to break.

The described mechanism for imposing a variable added tension on strand 18 is such that the added tension falls off rapidly as the diameter of the balloon increases, so much so that the total tension in strand 10 approaching the plying point decreases on a smooth curve from balloon diameter (1) to balloon diameter (2), in spite of the fact that the tension in the balloon proper increases as balloon diameter increases. The increased wraparound per so adds little or no back tension on the strand since the balloon generator is a freely rotating pulley and not a fixed surface on the flyer, as formerly.

With the apparatus of the invention, therefore, when the balloon diameter increases, the tension in strand 10 approaching the plying point decreases relative to the tension in strand 17. Thus, the strand 17 tends to become the core, more of strand 10 than of strand 17 is absorbed into the plied cord, and the excess strand 10 in the balloon is relatively quickly absorbed into the cord to return the balloon to its optimum diameter within its operating range. When the balloon decreases in diameter from its optimum diameter, the tension instrand 10 approaching point P increases. Strand 10 thus tends to become the core, more of strand 17 than of strand 10 is absorbed into the cord, the strand 10 is withdrawn from the balloon more slowly than it is fed thereinto from package 13 by means 12, and thus the balloon is quickly returned to its optimum diameter.

In the-second embodiment of the invention, shown in Pig. 3, the mechanism whereby variable retarding tension is imposed upon the first strand is of a-somewhat different character. in Fig. 3, however, parts which are similar to those in Figs. '1 andZ are designated by the same reference characters with an added prime. Itis to be understood that in such second embodiment'flyer 16 of Fig. 3is substituted for the fiyer 16 of Figs. 1 and 2.

The fiyer 16 of Fig. 3 has mounted therein the balloon generating pulley 6 which is reciprocable in a direction normal to the radial passage 62 in the flyer. Pulley 61 is rotatably mounted between upper and lower arms 74' on the forward end of a rod 70'. Such rodor shank Ytl'has an enlargement69' thereon which reciprocates in the bore 79 in the flyer, the rod 70 beingurged toward passage 62 by :the coil compression spring 66 acting between the rear of enlargement 69' and the.; forward inner face of annular nut 75' which slidably guides 6 the rear end of rod 70 and is threadedly retained in the rear end of the bore 79. The pulley 61 and its mounting rod 70' are thrust rearwardly, during rotation of the flyer, by the balloon which the pulley generates, the extent of rearward travel of the pulley with respect to the fiyer depending upon the degree of wrap-around, and thus the diameter, of the balloon 15'. Such travel of the pulley 61 relative to the fiyer is caused to govern the amount of added tension imparted to the strand 10 by the following mechanism. Radially inwardly of the pulley 61 and in position to cooperate with the strand 10' is a variable strand retarding means, generally designated 83, which includes the retarding shoe 81, projecting into passage 62 and fixed with respect to the flyer, and the cooperating confronting retarding shoe 82 mounted so that the strand 10 is pinched between the shoes. Shoe 82, which is in the form of a circular cylindrical cup, is mounted so that it is slidable, in the bore 84 in flyer 16, a short distance toward and away from shoe 81. The force with which shoe 82 is urged against the strand 10 as it is backed up by shoe 81 is determined by the coil compression spring 89 in shoe 82, the spring, as shown, acting between the forward closed inner end of shoe 82 and the abutment member 86 contacting the rear end of spring 89. Spring 89 is somewhat softer (exerts less compressive force) than spring 66. Abutment 86 is in the form of an arm integral with and projecting sidewardly from enlargement 69' on rod 70 into the interior of shoe 82 through a slot 85 extending longitudinally of such shoe.

When the wrap-around of balloon 15 is at its desired operatin value the balloon forces pulley 61' backward somewhat with respect to the flyer, as shown in Fig. 3, so that enlargement 6% is spaced a short distance from stop shoulder 88 in bore 79. This draws abutment 86 rearwardly, thereby lessening the compression of spring 89 from its maximum compression. Should the degree of wrap-around of the balloon 15 increase from such desired value, pulley 61', rod 70, and abutment 86 :are forced rearwardly with respect to the flyer 16', thereby lessening the degree of compression of spring 89 and thus lessening the retardation imposed on strand 10 by means 83. The means 83, springs 66' and 89, and pulley 61 are so related that as the degree of wrap-around of balloon 15' increases the total retarding tension on strand 10 decreases. In other words, upon expansion of the balloon the decrease in the retarding tension imparted to strand It) by means 83 is greater than the increase in the .tension in strand 10 cause-d by the increased wraparound of the balloon.

Accordingly the system of Fig. 3 is stable, since upon undue balloon expansion the second strand (17) becomes, in effect, the core, the rate of absorption of strand 10' into the plied cord is increased so that the rate of withdrawal of the strand 10 from the balloon momentarily exceeds the rate .at which the strand is fed into the balloon by means 12. Upon undue balloon contraction the strand 10 becomes, in effect, the core, .and the rate of its absorption into the plied cord is decreased, thereby to restore the balloon to its desired diameter.

In order not substantially to alter the path of strand 10 through means 83 upon changes of the position of pulley 61 with respect to the flyer, there is providedan idle guide pulley 91 journalled in the flyer to maintain strand 10' substantially axial of passage 62' in the path between pulley 91 and plying point P. The parts of the supporting means for pulley 61', the abutment 86, and the shoe 32 may be introduced into the indicated cavity in the fiyer 16 through an opening at the trailing edge of the flyer, such opening being thereafter closed by the member 90 held on the flyer by at least one stud, as shown, and having a tongue and groove connection 92. at at least one edge of the member 90 and the edge of the cavity in the flyer cooperating therewith.

I claim:

Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of -a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, and means on the shaft having a member engaging the first strand in the loop, said last named means being responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

. 2. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and loop-generating means on the shaft engaging the first strand at the end of the loop and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

3. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-olf package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, and strand retarding means on the shaft engaging the first strand at the end of the loop and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

4. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and loopgenerating and strand retarding means on the shaft engaging the first strand at the end of the loop and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand so as to maintain the loop within a predetermined desired diameter range.

5. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and loop-generating and strand retarding means on the shaft engaging the first strand at the end of the loop and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

6. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-olf package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, loop-generating means on the shaft responsive to changes in the shape of the loop, and strand retarding means on the shaft engaging the first strand in its passage from the loop therethrough, said last named means being controlled by the loop-generating means to decrease the retardation imposed upon the first strand when the loop increases in degree of wrap-around and to increase the retardation imposed upon the first strand when the loop decreases in degree of wrap-around to vary the tension of the first strand relative to the second strand in the portions thereof immediately approaching the plying junction.

7. Mechanism for twisting together two strands so as to form a twoply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, loop-generating means on the shaft responsive to changes in the shape of the loop, and strand retarding means on the shaft engaging the first strand in its passage from the loop therethrough, said last named means being controlled by the loop-generating means to decrease the retardation imposed upon the first strand when the loop increases in degree of wrap-around and to increase the retardation imposed upon the first strand when the loop decreases in degree of wrap-around to vary the tension of the first strand relative to the second strand in the portions thereof immediately approaching the plying junction, whereby to vary the relative rates of absorption of the first and second strands into the plied strand so as to maintain the loop within a predetermined desired diameter range.

8. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-olf package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, and strand retarding means on the shaft engaging the first strand in its passage from the loop therethrough, said last named means being operative in response to changes in the shape of the loop to decrease the retardation imposed upon the first strand when the loop increases in degree of Wrap-around and to increase the retardation imposed upon the first strand when the loop decreases in degree of wrap-around to vary the tension of the first strand relative to the second strand in the portions thereof immediately approaching the plying junction, the strand retarding means being so constructed and arranged that as the degree of wrap-around of the loop increases the total tension in the first strand approaching the plying junction decreases and as the degree of wrap-around of the loop decreases the total tension in the first strand approaching the plying junction increases.

9. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and strand retarding means on the shaft engaging the first strand in its passage from the loop therethrough, said last named means being operative in response to change in the shape of the loop to decrease the retardation imposed upon the first strand when the loop increases in degree of wrap-around and to increase the retardation imposed upon the first strand when the loop decreases in degree of wrap-around to vary the tension of the first strand relative to the second strand in the portions thereof immediately approaching the plying junction, the strand retarding means being so constructed and arranged that as the degree of wrap-around of the loop increases the total tension in the first strand approaching the plying junction decreases and as the degree of wrap-around of the loop decreases the total tension in the first strand approaching the plying junction increases.

10. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, a yieldable loop generating strand engaging means on the radially outer portion of the shaft adjacent the end of the loop, means resiliently urging the loop generating means against the first strand in the direction of rotation of the shaft, and means on the shaft engaging and retarding the first strand and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

l1. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-ofi strand package for a second strand, a rotatable shaft operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially consant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, a yieldable loop generating strand engaging means on the radially outer portion of the shaft adjacent the end of the loop, means resiliently urging the loop generating means against the first strand in the direction of rotation of the shaft, means on the shaft engaging and retarding the first strand and responsive to yielding of the loop generating means with respect to the shaft to vary the retardation imposed on the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand so as to maintain the loop within a predetermined desired diameter range.

12. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a balloon of the first strand and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the balloon, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and variable retarding means for the first strand,

said last named means comprising a balloon-generating strand-engaging roll on the radially outer portion of the shaft adjacent the end of the balloon, means mounting the roll for limited reciprocation with respect to the shaft in a direction generally normal to a radial axial plane through the shaft, means urging the roll forward with respect to the shaft in the direction of rotation of the shaft, a strand snubbing member close to the roll and fixed with respect to the shaft, the first strand in its travel from the balloon and radially inwardly of the shaft to the plying junction following a sinuous path over the forward surface of the roll and thence over the rear surface of the snubbing member.

13. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft operable to rotate a balloon of the first strand and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the balloon, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and variable retarding means for the first strand, said last named means comprising a balloon generating strand engaging roll on the radially outer portion of the shaft adjacent the end of the balloon, means mounting the roll for limited reciprocation with respect to the shaft in a direction generally normal to a radial axial plane through the shaft, means urging the roll forward with respect to the shaft in the direction of rotation of the shaft, means comprising a pair of relatively movable strand compressing members on the shaft engaging the,

first strand in its passage radially inwardly of the shaft to the plying junction, means urging such members relatively toward each other, and means responsive to movement of the roll with respect to the shaft to vary the last named means so that as the roll is progressively forced rearwardly with respect to the shaft by the balloon the strand compressing members engage the strand with a progressively smaller force.

14. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft having a fiyer operable to rotate a loop of the first strand about the let-off package and also to ply the two strands to gether, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, and strand tensioning means on the fiyer engaging the first strand and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

l5. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a, rotatable shaft having a fiyer operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the loop, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and strand ten sioning means on the. fiyer engaging the first strand and responsive to changes in the shape of the loop to vary the tension in the first strand in the run thereof approaching the plying junction whereby to vary the relative rates of absorption of the first and second strands into the plied strand.

l6. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a letoff strand,

package for a second strand, a rotatable shaft having a fiyer, operable to rotate a loop of the first strand about the let-off package and also to ply the two strands together, a first means for feeding the first strand into the loop, a second means for feeding the second strand to the junction where they are plied together, and loop-generating and strand retarding means on the fiyer responsive to changes in shape of the loop and engaging the first strand in its passage from the loop therethrough, said last named means being so constructed and arranged as to decrease the retardation imposed upon the first strand when the loop increases in degree of wrap-around and to increase the retardation imposed upon the first strand when the loop decreases in degree of wrap-around whereby to vary the tension of the first strand relative to the .second strand in the portions thereof immediately approaching the plying junction.

17. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, a rotatable shaft having a fiyer operable to rotate a balloon of the first strand and also to ply the two strands together, a first substantially constant speed means for feeding the first strand into the balloon, a second substantially constant speed means for feeding the second strand to the junction where they are plied together, and variable retarding means for the first strand, said last name-d means comprising a balloon-generating strand-engaging roll on the radially outer portion of the fiyer adjacent the end of the balloon, means mounting the roll for limited reciprocation with respect to the fiyer in a direction generally normal to a radial axial plane through the fiyer, means urging the roll forward with respect to the flyer in the direction of rotation of the fiyer, a strand snubbing member close to the roll and fixed with respect to the fiyer, the first strand in its travel from the balloon and radially inwardly of the fiyer to the plying junction following a sinuous path over the forward surface of the roll and thence over the rear surface of the snubbing member.

18. A strand twisting mechanism, comprising a driven shaft for rotating a loop of a strand, means for feeding the strand into the loop, means for withdrawing the strand from the loop in a run extending at least generally radially of the shaft, and strand engaging means on the shaft, said last named means including means for generating the loop and for imposing a first retarding tension on the generally radial run of the strand when the loop is of a small size and for imposing a progressively smaller retarding tension on such run as the loop increases in size.

.19. A strand twisting mechanism, comprising'means for rotating and guiding a loop of a strand, means for feeding the strand into the loop, and means for withdrawing the-strand from the loop, in a run extending at least generally radially of the means for rotating and guiding the loop, the loop rotating and guiding means including means for imposinga first retarding tension on the generally radial run of the strand when the loop is of a small size and for imposing a progressively smaller retarding tension on such run as the loop increases in size.

20. Mechanism for twisting together two strands so as to form a two-ply strand, comprising a source of supply of a first strand and a support carrying a let-off strand package for a second strand, means for rotating and guiding a loop of the first strand about the let-off package and also to ply the two strands together at a plying junction, means for feeding the first strand into the loop, means for feeding the second strand to the plying junction, and means to withdraw the plied strand from the plying junction, the run of the first strand withdrawnfrom the loop and approaching the plying junction being maintained at least generally radially of the loop rotating and guiding means, the loop rotating and guiding means including means for imposing a first retarding tension on the generally radial run of the-first strand approaching ing the strand from the loop in a run extending at least 7 generally radially into the shaft, and strand engaging means on the shaft, said last named means including means i for generating the loop and means for deflecting and when the loop is of a small diameter and to impose a progressively smaller retarding tension thereon as the loop increases in diameter.

References Cited in the file of this patent UNITED STATES PATENTS