WO1992008841A1

WO1992008841A1 - Improvements in or relating to stranders

Info

Publication number: WO1992008841A1
Application number: PCT/GB1991/002008
Authority: WO
Inventors: Terence Anthony Thomas Pettitt
Original assignee: The Northampton Machinery Company Limited
Priority date: 1990-11-15
Filing date: 1991-11-14
Publication date: 1992-05-29
Also published as: AU8868691A; GB9024846D0

Abstract

A planetary cable strander (5, 8) for manufacturing cables is described. In the past planetary cable stranders (5, 8) have suffered from vibrational problems. There was also a problem of individual strands becoming trapped because reels were forced in alternate directions as a result of centripetal force. The invention provides a planetary cable strander wherein reels (15) are supported on the strander. The axes of rotation of the reels are substantially parallel to the main axis of rotation of the strander (5, 8). Mechanical brakes and guides are provided for each reel and these act to guide unwinding fibres and to maintain them at a predetermined tension so as to ensure that even cable winding takes place.

Description

Improvements in or relating to Stranders.

This invention relates to . stranders, and more specifically it relates to planetary stranders which are used to manufacture or armour cables . Cables manufactured by planetary stranders have no twist imposed on their constituent strands or fibres.

Planetary stranders are well known in the field of cable stranders. The planetary strander consists of a series of solid discs which share a common central axis about which the discs rotate. Each disc supports several cradles which in. turn each support a reel or spool. Each spool carries a single or multiple strand of wire used to produce or armour cables.

When the cable is manufactured the strands are drawn off their spools and they pass through orifices in the discs. As the discs rotate the strands move parallel to the main shaft and are eventually wound together and drawn into a cable of desired characteristics and length. A cradle supports each of the reels so that they remain in the same orientation whilst the discs are rotated. The cradles are fitted onto the discs, so that, by virtue of a sun and planetary gearing system or a crank ring system remain in the same orientation during the cable manufacturing process. The advantage of arranging the cradles in this configuration is that because they remain the same way up throughout rotation, no twist is imparted to fibres. This is important when forming cables from fibre optic cable, flexible insulated cables, or steel, as axial twist on the cable may damage it or alter its desired characteristics. However in some special cases the gearing of a planetary strander may be arranged to allow small progressive changes of orientation of the cradle on each revolution of the disc in order to impart slight over twist or back twist to the wire or fibre. In the usual configuaration the reel is mounted in the cradle with the reel axis at 90 to the carriage axis.

Although planetary stranders have been very successful, they have in the past suffered from vibrational problems. One reason for this is that the rotational velocity of the discs may be of the order of up to 150 to 200 revolutions per minute (rpm). At this speed the reels and the wire on the reels is forced in alternate directions as the carriage rotates. This effect tends to lead to two major problems. Firstly there is a greater risk of a strand becoming trapped, with the ensuing risk of it snapping. Secondly the vibrational problems give rise to much wear on the cradle and reel supports. In the former case the length of cable being manufactured, which may be several kilometres long, may be scrapped or require joints. In addition it is very difficult to detect such breakages when they occur, and re-threading the strander is both costly and time consuming. In the latter case the wear has given rise to excessive maintenance costs, high noise level and reduction of running speed.

The problem of threading the machine is always present when setting up the machine for a new run of cable and it is clearly undesirable to have expensive stranding machinery lying idle for a large amount of time, whilst it is being set-up for a new run of cable.

There has also been a considerable noise problem as a result of the clatter when the machine is running at high speed.

According to a first aspect of the present invention there is provided a support for use with a planetary cable strander, the support being adapted to be mounted on the cable strander such that in use a reel supported thereby has its axis substantially parallel to the main access of rotation of the strander.

Preferably the support is in the form of a cradle. A cradle may not be used, its place may be taken by a reel with its spindle and flyer being mounted directly on to the side of the discs. Other reel support means may be provided, as is well known to those skilled in the art.

Preferably the cradle is adapted to be mounted on a disc on the strander. The disc is arranged such that it lies substantially perpendicular to the axis of rotation of the cable strander.

Preferably the cradle is for use with a planetary strander and means is provided to guide a fibre from the reel supporting the fibre to a point from which the fibre runs parallel to the axis of rotation of the disc. The guide may be a flyer-arm which "floats" above the surface of the wound fibre as it unwinds from the reel. A pulley may be supported by the flyer-arm so that the fibre is always removed from a position which is substantially perpendicular to the axis of the reel. This facilitates the smooth unwinding of the fibre.

Means may be provided to control the flyer arm. This may comprise a timing belt and/or mechanical gear or other device to keep the flyer arm in planetary motion or near planetary motion as required for varying degrees of back twist. Balast may be provided on the flyer-arm to counter balance the weight of the pulley. A tension control by way of a mechanical brake may be used to control the tension in the wire-arm. The brake may be linked to a so-called spring dancer which regulates the brake in accordance with the fibre unwinding. Alternatively electric motors may be used to control the tension of the reel or spool as it unwinds, so that the tension of the fibre may be varied electronically by using suitable sensors and providing appropriate feedback signals indicative of tension in the fibre further "down line".

A roller may be provided which rests against the unwound fibre on the spool . This is because normally the tension varies as the wire is unwound from the reel and it is necessary to compensate for the varying diameter of the spool using a suitable mechanism. The aforementioned roller detects the wound diameter of the wire on the spool and adjusts the brake setting, thus keeping the tension in the wire at a constant value.

According to a second aspect of the present invention a planetary cable strander comprises a central drive shaft, a rotatable member mounted on the shaft, plurality of reels supported on the member, the axes of the reels lying substantially parallel to the main axis of the shaft.

A flyer-arm may be associated with each reel. Gears are provided to rotate the drive shaft. Means may be provided to draw the cable so that on rotation of the drive shaft and activation of the cable drawing means, cable of the desired length having the desired characteristics is pulled.

As a result of the above mentioned modifications it is possible to produce a strander which is overall shorter in length.

Because the axes of the reels are now all parallel and because of the manner in which they are mounted on respective discs, changing spent reels becomes much easier than in existing stranders . A corollary of this is that re-loading the strander before a new run of cable is also much simpler than before. The discs supporting spent reels are rotated into a position adjacent a table-like surface. The empty reels are unlocked from their supports and then rolled onto the table surface, down a shute and stored. New reels are then rolled into position and locked onto the discs. The table height may be raised so as to permit a fork lift truck to re-load new reels.

Mechanical tensioning devices connected to each flyer arm may be provided. Alternatively electric tensioners may be provided which control a brake on each reel directly. Sensors may be provided throughout the machine to give a feed-back signal according to the actual and desired tension in each strand or fibre. This signal may be used to actuate the braking means.

Because the axes of the reels are all parallel to the carriage axis as the carriage rotates the forces acting on the reels and wires are all radial and movement caused by the alternating forces in the conventional layout are not present. Embodiments of the present invention will now be described by way of examples only and with reference to the Figures in whic :-

Fig. 1 shows a longitudinal section of an assembly line with two planetary stranders, used to produce a multi-core cable;

Fig. 2 shows an end view of one of the planetary stranders and a diagramatical view of a fork-lift truck reloading spent reels;

Fig. 3 shows a part section of a strander showing in detail the main shaft and a disc which supports a cradle;

Fig. 4 shows an end view along the section line A-A of Fig. 3;

Fig. 5 shows a part section through an alternative embodiment of a shaft showing a disc supporting the cradle;

Fig. 6 shows an end view along the section line B-B of Fig. 5;

Fig. 7 shows a section through another embodiment of the disc supporting the reel; and Fig. 8 shows an end view along the section line C-C of Fig. 7.

Referring to Fig. 1 a production line for the drawing and winding of cable is shown generally at 1. A drum 2 stores core cable 3. Core cable 3 may be the cable which is to be armoured or it may be a core support for other cables. The core cable 3 passes through a powderiser 4, then through a first stranding machine 5, through a tensioner 6 and then through a further powderiser 7. A second strander 8 is used to provide another layer of strands to the cable. The cable then passes through a tensioner 9 a second coating machine 10 and a machine which wraps and binds the resulting cable. The cable is then drawn by a drive system 12 and eventually rolled onto a drum 13 as the finished product.

Fig. 2 shows how the invention facilitates easy removal of spent reels and reloading of full reels. The spent reels of cable 15 are allowed to roll down shute 16, after they have been released from the disc 17. A fork lift truck 18 then delivers full reels 19 to a position proximal to the disc 17. By rotating the disc through 90 degrees so that the vacant space for the reel lies substantially adjacent the surface 20 of the table 19 it is possible to roll a full reel into position and connect it to the disc 17. This has been difficult in the past because of the orientation of the full reels in respect of the disc and their bulk and weight when full of cable.

Referring to Fig. 3 a detailed view of two of discs 31 and 32 within the strander 1 is shown in section. The main shaft 30 is shown supporting the discs 31 and 32. A reel 33 is shown supported on disc 31. The reel 33 is supported by pintles 34 and 43. The pintle 34 is actuated by way of a sliding drive dog 35 which is attached to pinnion 36.

Cable 37 unwinds from the reel 33 and passes over pulley wheel 38. The pulley wheel 38 is supported on a flyer arm 39. Cable 37 then passes around a second pulley 40, through an orifice 41 in the plate 32 and around a further pulley 42. The cable 37 then passes to a point where it moves parallel to the main axis of the strander. The flyer arm 39 is mounted on the shaft 41 which is driven by the planetary gearing or similar mechanism in order that the wire being unwound from reel 33 does not twist about its own axis. Fig. 4 shows an end view of the device of Fig. 3 along the line A-A. Pulley wheel 38 is shown with the cable 37 passing over it. The pulley wheel 38 appears to be slightly parabloid in shape, the reason for this is that the plane in which the pulley wheel sits is off-set with respect to both the plane of the disc 31 and the . plane passing through the axis of reel 33. The reason for this is that it is necessary for the pulley wheel 38 to lie at such an angle as to be able to follow the path of the unwinding cable 37 in the most favourable manner.

An spring loaded brake band 45 passes around pulley wheel 43 around the main shaft 44 of the flyer-arm 39 and is connected to two swivel joints 46A and 46B. The purpose of this brake band is to apply a braking torque to the reel 33 and thereby impart tension into the wire being unwound from reel 33.

Referring to Figs. 5 and 6 the difference between this arrangement and that shown in Figs. 3 and 4 is in the method of tensioning the wire being unwound from reel 33. In Figs. 5 and 6 pulley 38 is mounted on an arm pivoted on flyer arm 39. This pivoted arm connects to a brake lever loaded by an adjustable spring mechanism. This brake lever applies torque to the reel 33 and thereby tension in the wire. The tension in the wire passing over pulley 38 causes the pivoted lever to tend to release the brake and thus the system comes into a state of equilibrium and a constant tension is maintained in the wire. The wire 37 is drawn off the reel 33 over the pulley 38 and round pulley wheel 40 and then over the third pulley wheel 32 and finally onto a fourth pulley wheel 47. After which it is then drawn parallel to the main axis to the shaft and through further discs of the strander.

Fig. 6 shows an end view of the embodiment of Fig. 5 with like parts showing the same reference numbers.

Referring to Figs. 7 and 8 in which like parts bearing the same reference numerals as in Figs. 3 and 6. The difference between this arrangement and that in Figs. 3 and 6 is the method of imparting tension into the wire. In this method reel 33 is completely free to rotate with respect to the flyer arm 39 there being no friction brake fitted as in Figs. 3 and 5.

Instead, the opposite side of reel 33 i.e. nearest to the disc 31, is driven by a drive plate mounted on pintle 34. The pintle is connected by a drive belt to a small electric motor 48. This motor is controlled by a tension measuring device mounted elsewhere on the carriage. The output signal from the measuring device then causes the electric motor to apply a braking torque to the reel 33 of the required magnitude to produce the desired tension in the wire 37. For very low tension levels the motor can apply a driving torque sufficient to partially overcome friction such that the remaining frictional torque can be used to produce the required reduced tension in the wire.

In this configuration it is a further benefit that unlike the conventional layout where electric motors mounted in the cradle for tensioning purposes will require slip ring electrical connection between the cradle and the disc, in this case since the motor can now be mounted directly on to the disc the complication of slip rings is avoided. This is of particular benefit since passing electrical signals through slip rings can be troublesome.

It will be appreciated that variations may be made to the embodiments without departing from the scope of the invention. Similarly it will be appreciated that when reference is made to the perpendicular removal of wire from a reel the wire may be removed at angles substantially less than 90 ; but are preferably removed at a point perpendicular to the reel.

Claims

1. A support for a reel for use with a planetary cable strander, the support being adapted to be mounted on the cable strander, the cable strander having an axis of rotation, such that in use the supported reel has its axis parallel to the axis of rotation of the cable strander.

2. A support according to claim 1 wherein the support is in the form of a cradle.

3. A support according to claim 2 wherein the support has a spindle and a flyer, the spindle and the flyer being mounted on a disc.

4. A support according to claim 3 wherein the disc is arranged substantially perpendicular to the axis of rotation of the cable strander.

5. A support according to claim 3 wherein the support is adapted to be mounted on a disc of the strander, the disc being arranged such that it is substantially perpendicular to .the axis of rotation of the cable strander.

6. A support according to any preceding claim wherein means is provided to guide a fibre from a reel supporting the fibre to a point from which the fibre runs parallel to the axis of rotation of the cable strander.

7. A support according to claim 6 wherein the means for guiding the fibre comprises a flyer arm arranged to follow an unwinding fibre from a reel.

8. A support according to claim 7 wherein a pulley is supported by the flyer arm the fibre being removed from a reel such that its axis lies substantially perpendicular to the axis of rotation of the reel.

9. A support according to claim 7 or 8 wherein means is provided to control the flyer arm.

10. A support according to claim 9 wherein the means for controlling the flyer arm comprises a timing belt.

11. A support according to claim 9 wherein the means for controlling the flyer arm comprises a mechanical gear.

12. A support according to any of claims 9 to 11 wherein the flyer arm is provided with ballast so as to counter-balance the weight of the pulley.

13. A support according to claim 11 or 12 wherein a tension control device is provided so as to maintain the unwinding fibre at a constant tension.

14. A support according to claim 13 wherein the control of tension of the fibre is by way of suitable sensors arranged to provide a feed back signal, the feed back signal being used to control a braking device.

15. A support having a roller which rests against an unwound portion of the fibre supported on the reel, the roller being able to apply different amounts of friction to an unwinding reel by detection of the amount of remaining fibre on the ree1.

16. A support according to claim 13 or 14 wherein the tension in the fibre is controlled by way of an electric motor acting so as to prevent the reel supporting the fibre, from rotating.

17. A planetary cable strander comprises a central drive shaft, a rotatable member mounted on the shaft, a plurality of reels supported on the ' member, the axes of the reels lying substantially parallel to the main axis of the shaft.

18. A planetary cable strander according to claim 17 wherein a flyer arm is associated with at least one of the reels.

19. A planetary cable strander according to claims 17 or 18 wherein gears and/or a timing belt are provided to rotate the drive shaft.

20. A planetary cable strander according to claim 17 wherein means is provided to draw the cable such that on rotation of the drive shaft; and activation of a cable drawing means, cable of a predetermined length having predetermined characteristics is pulled.

21. A planetary cable strander according to any of claims 17 to 20 wherein a mechanical tensioning device is connected to a flyer arm.

22. A planetary cable strander according to any of claims 17 to 20 wherein an electrical tensioning device is connected to a flyer arm.