US3593508A

US3593508A - Apparatus for imparting a predetermined value of twist to a material

Info

Publication number: US3593508A
Application number: US731454A
Authority: US
Inventors: Ludwik Jachimowicz; Adolf S Knott
Original assignee: General Cable Corp
Current assignee: General Cable Corp
Priority date: 1968-05-23
Filing date: 1968-05-23
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20
Also published as: GB1269526A; SE360127B; CH493690A; FR2009172A1; DE1925991A1; ES367586A1

Abstract

An apparatus for imparting a predetermined twist to a multistrand cable during takeup in which a cable twisting unit is mounted for rotation about the axis of said cable and includes a twist imparting means of flexible cylindrical material of endless length and coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable thereby transmitting twist force to said cable to provide a predetermined twist in said cable. A braking means is associated with the cable twisting unit to vary the twisting force transferred by the twist imparting means to the cable and is controlled by a twist sensor sensing variations from the predetermined twist.

Description

United States Patent Inventors Ludwik .lachimowicz Elizabeth; Adolf S. Knott, Roselle, both of, NJ. Appl. No. 731,454 Filed May 23, 1968 Patented July 20, 1971 Assignee General Cable Corporation New York, N.Y.

APPARATUS FOR LMPARTING A PREDETERMINED VALUE OF TWIST TO A MATERIAL Prim'ary Examiner-John Petrakes Attorney-Sandoe, Neill, Schottler & Wikstrom ABSTRACT: An apparatus for imparting a predetermined twist to a multistrand cable during takeup in which a cable twisting unit is mounted for rotation about the axis of said cable and includes a twist imparting means of flexible cylindrical material of endless length and coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable thereby transmitting twist force to said cable to provide a predetermined twist in said cable. A braking means is associated with the cable twisting unit to vary the twisting force transferred by the twist imparting means to the cable and is controlled by a twist sensor sensing variations from the predetermined twist.

PHOTOCELL PATENTEUJUL20I9T| 3593508 SHEET 2 UF 2 35 DC Source TWIST SENSOR UNIT APPARATUS FOR IMPARTING A PREDETERMINED VALUE OF TWIST TO A MATERIAL BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to an apparatus for imparting twist to a multistrand cable and more particularly for imparting a predetermined value of twist to successive portions of a cable during takeup.

2. Description of the Prior An In the forming of multistrand cable, it is necessary and desirable to supply an additional twisting force to the cable above that produced by the operation of the takeup cradle and reel in order to balance the tendency of the cable to untwist during its progress toward take-up. It is also desirable that the cable core be compressed to substantially uniform cylindrical shape prior to application of the wrapper to the cable core.

Prior art apparatus representative of attempts to achieve the foregoing objects is disclosed in 11.8. Pat. No. 3,25 1 ,I79 to L. O. Reichelt et al. Reichelt discloses material twisting apparatus including a flat belt in gripping engagement with the cable and driven by a rotating twisting head which is rotatedin synchronization with the progress of the cable and the rotation of the takeup cradle and reel. If the apparatus is synchronized with the advance of the cable and for an instant the linear progress of the cable slows down, then the loop of the belt in engagement with the cable will have a tendency to advance along the cable. However, since .the loop cannot advance and is fixed in a position relative to the apparatus, the belt will pull on the cable untwisting it with whatever force is needed to provide sufficient lengths of belt 'to compensate for the change in linear progress of the cable. As a result, the belt will have a tendency to damage the insulation of the cable when there are surges in the linear progress of the cable.

The flat belt utilized by the Reichelt apparatus can be applied to the cable core only at a fixed angle appropriate for the speed of rotation and cable diameter. If these conditions change, the angle must be adjusted or the belt will not lie parallel to the surface of the cable and as a result, one edge of the belt will buckle and the other edge will cut into the insulation of the cable core.

SUMMARY OF THE INVENTION The present invention provides an apparatus for imparting a predetermined twist to a multistrand cable by applying to the cable a controlled torque. A cable will have a longer lay away from'the takeup cradle and reel than at the takeup cradle and reel. To make the lay essentially the same at any point along the cable, a torsion force of predetermined value must be applied to the cable prior to takeup in addition to that produced by operation of the takeup cradle and reel. If this force is substantially constant and independent of irregularities in the advance of the cable, then the'lay will be substantially the same at any point along the cable. To this effect, a cable twisting unit is mounted for rotation about the axis of the cable and includes a twist imparting means of flexible cylindrical material of endless length having a winding path of a plurality of helical turns around said cable and in engagement with said cable transmitting twisting force to said cable to provide a predetermined twist in said cable. Braking means associated with the cable twisting unit varies the twisting force transferred by the twist imparting means to the cable in response to variations from the predetermined twist as detected by a twist sensor. A

slack compensator is provided in engagement with the twist imparting means and responsive to variations in the length of the'winding path of said twist imparting means to maintain the twist imparting means relatively taut.

It is an object of the invention to supply a predetermined twist to a multistrand cable.

It is a further object to achieve essentially constant lay of the cable attakeup.

It is another object of the invention to provide a twist imparting means which compresses the cable into a substantially circular configuration without damaging the strands of the multistrand cable.

It is an additional object of the invention to provide a cable twisting unit for imparting a predetermined twist to multistrand cable irrespective of irregularities in the advance of the cable produced by changing cable diameter and speed up or slow down of takeup.

Other objects, advantages and novel aspects of the inven tion will become apparent upon consideration of the following detailed description in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevational view of a cable twisting apparatus in accordance with the present invention.

FIG. 2 is a force diagram showing the manner in which the twist force is imparted to the cable.

FIG. 3 is a sectional view of the'unit as taken along the line Ill-Ill of FIG. I.

FIG. 4 is a schematic view of'the control circuit by which the twisting force imparted to the cable is varied responsively to variations from predetermined twist.

FIG. 5 is a diagrammatic view of the photocell unit ofa twist sensorfor determining variations from predetermined twist.

DESCRIPTION OFPREFERRED EMBODIMENTS Referring to FIG. I of the drawings, several cable com ponents I from payoff reels (not shown) pass through stationary apertured face plate 2 and a closing die 3 into engagement with one another to form a multistrand cable 4. The cable 4 progresses from left to right and the right-hand end of the cable is twisted as shown by an arrow A, to provide a lefthanded twisted cable at a distance spaced from the closing die 3. The cable enters takeup cradle 7 and advances to and is wound onto a takeup reel (not shown). The cradle and reel may be of a construction known in the art such as that shown in US. Pat. No. 3,251,179 to L. O. Reichelt et al.

The rotation of the cradle 7 effects the twisting of the portion of the moving cable 4 which extends from the stationary closing die 3 to the takeup cradle 7. In the absence of a cable twisting unit of this invention, the twisting of the cable 4 by the cradle 7 is such that the cable has a longer lay away from the cradle than adjacent the cradle. To make the lay of the cable 4 essentially the same at any point along the cable, a cable twisting unit is located between takeup cradle 7 and the closing die 3 and at a predetermined distance from the latter and serves to apply an additional amount of twist of predetermined value to successive portions of cable 4. In the embodiment shown in FIG. 1, two cable twisting units 12, diametrically opposed are utilized to impart a predetermined twist to cable 4. Since cable twisting units 12 are identical the description of one will apply to the other.

The cable twisting unit 12 is mounted on rotary frame 14 for rotation about the axis of cable 4 in

bearings

15 and 16. The cable twisting unit 12 includes a twist imparting means of flexible cylindrical material of endless length such as rope l7 coursing a helical winding path 18 of a plurality of helical turns around and in engagement with cable 4 with the length of said winding path being the distance between the point of entry of rope 17 into engagement with cable 4 and the point of exit of rope 17 from engagement with cable 4.

The rope I7 is directed onto the cable by sheave 22. Upon leaving cable 4, the rope 17 is received by and passes over sheave 23 and slack compensation sheave 24 back to sheave 22. Sheave 24 is connected by a spring 25 to a mounting block 26 attached to frame 14.

A braking means 30, which may be a magnetic brake or clutch, is mounted on frame 14 in association with sheave 22 to apply a predetermined tension to the rope 17, causing the rope 17 to impart a predetermined value of twist to cable 4. As the length of the winding path 18 of the rope I7 about cable 4 changes due to changes in the diameter of the cable, spring 25 allows sheave 24 to move longitudinally of the axis of cable 4 responsive to variations in the change in length of the winding path 18 thereby maintaining substantially constant tension in rope l7 and imparting the predetermined value of twist to cable 4.

As shown in the force diagram FIG. 2, the force F applied to cable 4 by rope l7 resolves into the forcesf, and f, the latter acting longitudinally along the cable axis and the former being tangential to the cable circumference The rope 17 has a sufficient number of turns around cable 4 to provide slipless contact between rope 17 and cable 4. The number of turns required is a function of the coefficient of friction of the rope 17 against the cable 4 and the tension applied to the rope 4 by braking means 30. Because the rope I7 is a flexible cylindrical material, it is capable of compressing the strands of cable 4 into a substantially cylindrical configurations not obtainable by other twist imparting means without damage to the strands of cable 4.

Only the force facts to supply twist to cable 4 and to optimize the twist imparted by rope I7 to cable 4, the angle at which the rope is directed onto the cable is an acute angle of small measure. Where there are changes in cable diameter as the cable progresses from closing die 3 to takeup cradle 7, there will be changes in the winding path 18, and in order to maintain substantially constant tension in the rope 17, the angle a will vary and the sheave 24 will be caused to move longitudinally of the axis of the cable 4, responsive to variations in the winding path, in order to take up the excess length of rope l7 and keep tension in the rope substantially constant. In a representative application of the invention where it is desired to produce a lay of about 2 inches for cable diameters froml'b inches to 3 inches, the angle a from 12 to 23 and the ratiofl/F RF from 97 to 92 percent.

In the embodiment of the invention shown in FIG. I, the angle of entry of the rope onto the cable varies, but the speed of rotation of the frame is fixed in a ratio to the speed of the cradle. In an alternative embodiment, the angle of entry of the rope onto the cable is fixed, and the rotation of the frame 14 in FIG. 1 must be increased as the cable diameter decreases, and the rotation of frame 14 must be decreased as the cable diameter increases. While this alternative embodiment enables the utilization of a large ratio f,/F as high as 97 percent for all cable diameters, it requires more control by the machine operator.

The embodiment ofthe invention shown in H6. I is self-adjusting within minor irregularities of the machine run so that no elaborate control and feedback mechanisms are needed. With the ratio of rotation of the cradle 7 and the frame 14 of the cable twisting unit 12 fixed and the setting of braking means 30 fixed to apply a predetermined tension to rope 17, it may occur that the longitudinal speed of the cable may vary somewhat, especially at starting and stopping of the machine when slack is formed or taken up in the cable 4. In these cases, a change in angle of application and takeup of the flexible twist imparting means, rope 17, will be caused by the movement of slack compensation sheave 24.

By maintaining the tension on rope 17 substantially constant through movement of sheave 24, under the force of spring 25 the predetermined tension applied to rope 17 produces a force in rope 17 causing a predetermined twist to be imparted to cable 4 in addition to the twist produced in cable 4 by the takeup cradle 7. By the addition of this predetermined value of twist to the cable, the lay of the cable between the cable twisting unit 12 and the takeup cradle 7 will be within a predetermined range. Thus, the lay will be substantially the same along the cable between the cable twisting unit 12 and the takeup cradle 7.

In FIG. 4 the field winding 32 of the braking means 30 is shown connected to a source of DC voltage 35 by terminal leads 36 and 37. The DC voltage is achieved through the use ofa full wave rectifier 38 rectifying a 1 l v. source of AC voltage. Field winding 32 is connected to rectifier 38 and in series with control rheostat 40, and a field rheostat 42 through terminal leads 36 and 37. In order to produce a predetermined tension in rope l7 and thereby impart a predetermined twist to cable 4, the field rheostat 42 will be set at one of the terminals a, b, c, d or e. Depending upon which terminal setting of the field rheostat 42 is utilized, the field flux of braking means 30 will be increased or decrease, thus increasing or decreasing the braking force of braking means 30 and the tension applied to rope l7.

In a particular application shown in FIG. 4, the field rheostat 42 is set at terminal 12 causing braking means 30 to apply a predetermined tension to rope 17 to impart a predetermined twist in cable 4 thereby establishing a predetermined lay in the cable between the cable twisting unit I2 and the takeup cradle 7. In the event that there is a prolonged and substantial variance from the predetermined lay of cable 4, a twist sensor unit 44 is caused to operate the control rheostat 40. The means to detect the substantial variance from the predetermined lay of cable 4 is shown diagrammatically in FIG. 5 as three

photocells

46, 47 and 48 which comprise the detection portion of twist sensor 44. The photocells are located at a fixed distance from a printing wheel 49 which distance is equal to the predetermined lay of the cable. The printing wheel 49 will imprint on the cable a legend or symbol to be detected by the photocells 46. The lay of the legend corresponds to the lay of the cable 4. Whenever the legend disappears from the view of photocell 46, i.e. the lay varies from the predetermined lay of the cable, twist sensor 44 is actuated and depending upon whether the legend is in the view of

photocell

47 or 48, twist sensor 44 recognizes that the lay of the legend is shorter or longer than the predetermined lay of the cable. The twist sensor 44 operates the control rheostat 40 so that where the lay is longer than the predetermined value of lay, i.e. the legend is within the view of photocell 48, the setting of control rheostat 40 will be decreased changing the value of field flux and thus increasing the braking force of braking means 30. The increase in braking force will increase the tension applied to rope 17 causing it to impart increased twisting force to cable 4. When the lay of the legend returns to its predetermined value, i.e. the legend is within the view of the photocell 46, twist sensor 44 is deactuated.

While the invention has been described through disclosure in the above embodiments, it should be noted that various modifications made evident to workers in the art by reason of the disclosure may be incorporated in further practical embodiments. For example, while the operation of a single cable twisting unit 12 has been described, FIG. 1 shows two cable twisting units disposed diametrically opposite each other which will produce the desired predetermined twist in cable 4. Further, more than one rope could be run off sheave 22. Rope 17 could be replaced by three or more ropes, all directed from sheave 22 and each having their own takeup sheaves 23 and slack compensating sheaves 24.

Also, instead of having two cable twisting units 12 diametrically opposed, units could be placed in four quadrants. Further, any control circuitry capable of sensing changes in lay of a cable from a predetermined value can be utilized to vary the braking torque of brake 30. These and other modifications may be made without departing from the scope of the claims.

We claim:

1. Apparatus for imparting a predetermined twist to a multistrand cable during takeup comprising:

a. a cable twisting unit including a frame mounted for rotation about the axis of said cable and including also a torque imparting means having an element of endless length and coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable for transmitting torque to said cable to provide a predetermined twist in the said cable; said endless element being movable with respect to the frame along said winding path, and

b. braking means associated with said cable twisting unit and opposing movement of the endless element along said winding path to apply a controlled torque to the cable by said endless element.

2. The apparatus for imparting a predetermined twist in said cable claimed in claim 1 wherein the apparatus includes a twist sensor to sense variations from said predetermined twist to control said braking means to vary the twisting torque in response to said variations.

3. The apparatus for imparting a predetermined torque in said cable claimed in claim 2 wherein said twist imparting means is of flexible cylindrical material.

4. The apparatus for imparting a predetermined torque in said cable claimed in claim 2 wherein the twist imparting meansare made of flexible cylindrical material and the cable twisting unit includes first means to direct said torque imparting means onto said cable and second means to receive said torque imparting means from said cable.

5. The apparatus for imparting a predetermined twist in said cable claimed in claim 4 wherein said first means is a sheave and said second means is also a sheave, and the twisting unit includes also slack compensation means, in engagement with said torque imparting means and responsive to variations in the length of the winding path of said torque imparting means to maintain substantially constant tension in said torque imparting means.

6. The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein the slack compensation means comprises a sheave in engagement with said torque imparting means and moveable longitudinally of the axis of said cable and responsive to variations in the length of the winding path of said torque imparting means to maintain substantially constant tension in said torque imparting means.

7. The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein said braking means is a magnetic clutch and said twist sensor comprises first means to sense variations in the lay of said cable and second means connected with said magnetic clutch to vary the flux of said magnetic clutch in response to variations in said lay.

8. The apparatus for imparting a predetermined twist in said cable claimed in claim 7 wherein said twist sensor comprises photocell means to sense variations in the lay of said cable and circuit means connected to said magnetic clutch and actuated by said photocell means to vary the flux of said magnetic clutch in response to variations in said lay.

9. The apparatus for imparting a predetermined twist in said cable claimed in claim 5 wherein the first sheave is positioned to direct the torque imparting means on to the cable at an acute angle to the axis of the cable.

10. The apparatus for imparting a predetermined twist in said cable claimed in claim 9 wherein the acute angle varies between l2 and 23.

11. The apparatus for imparting a predetermined twist in said claimed in claim 2 wherein there are:

a. first and second cable torque imparting means mounted on the frame and diametrically opposite one from the other for common orbital rotation about the axis of said cable and each including an endless length element of flexible cylindrical material coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable transmitting torque to said cable to provide a predetermined twist in said cable, each cable torque imparting means including a first sheave to direct the endless length element onto said cable, a second sheave to receive said endless length element from said cable, a third sheave adapted to receive said endless length element from said second sheave and to guide said endless length element to said first sheave and movable longitudinally of the axis of said cable in response to variations in the length of the winding path of said endless length element to maintain substantially constant tension in said endless length element;

b. the braking means including magnetic clutch means associated with said first and second cable torque imparting means to vary the torque transferred by each of said endless length elements to said cable; and c. the twist sensor having first means to sense variations in the lay of said cable and second means connected with said magnetic clutch means to vary the flux of said magnetic clutch means in response to variations in said lay.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 593, 508 Dated Jul[ 20; 1971 Inventods) Ludwik Jachimowicz et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 34,

ft/P RF. should read f /F.

Signed and sealed this 23rd day of May 1972.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents FORM PO-IOSO (10-69! USCOMM DC eovsqnbg u 5, GOVERNMENT PRINTING ornc: 1909 o-sss-su

Claims

1. Apparatus for imparting a predetermined twist to a multistrand cable during takeup comprising: a. a cable twisting unit including a frame mounted for rotation about the axis of said cable and including also a torque imparting means having an element of endless length and coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable for transmitting torque to said cable to provide a predetermined twist in the said cable; said endless element being movable with respect to the frame along said winding path, and b. braking means associated with said cable twisting unit and opposing movement of the endless element along said winding path to apply a controlled torque to the cable by said endless element.

4. The apparatus for imparting a predetermined torque in said cable claimed in claim 2 wherein the twist imparting means are made of flexible cylindrical material and the cable twisting unit includes first means to direct said torque imparting means onto said cable and second means to receive said torque imparting means from said cable.

10. The apparatus for imparting a predetermined twist in said cable claimed in claim 9 wherein the acute angle varies between 12* and 23* .

11. The apparatus for imparting a predetermined twist in said claimed in claim 2 wherein there are: a. first and second cable torque imparting means mounted on the frame and diametrically opposite one from the other for common orbital rotation about the axis of said cable and each including an endless length element of flexible cylindrical material coursing a winding path of a plurality of helical turns around said cable and in engagement with said cable transmitting torque to said cable to provide a predetermined twist in said cable, each cable torque imparting means including a first sheave to direct the endless length element onto said cable, a second sheave to receive said endless length element from said cable, a third sheave adapted to receive said endless length element from said second sheave and to guide said endless length element to said first sheave and movable longitudinally of the axis of said cable in response to variations in the length of the winding path of said endless length element to maintain substantially constant tension in said endless length element; b. the braking means including magnetic clutch means associated with said first and second cable torque imparting means to vary the torque transferred by each of said endless length elements to said cable; and c. the twist sensor having first means to sense variations in the lay of said cable and second means connected with said magnetic clutch means to vary the flux of said magnetic clutch means in response to variations in said lay.