GB2234267A

GB2234267A - Cable twisting apparatus

Info

Publication number: GB2234267A
Application number: GB8916471A
Authority: GB
Inventors: Paul Brian Barlow; John Philip Vale
Original assignee: DELTA ENFIELD Ltd
Current assignee: DELTA ENFIELD Ltd
Priority date: 1989-07-19
Filing date: 1989-07-19
Publication date: 1991-01-30
Anticipated expiration: 2009-07-19
Also published as: EP0409621A1; GB2234267B; GB8916471D0

Description

101 - i X :2:; 13 -4 -- -- CJ CABLE IMING-UP APPARATUS The present

invention relates to apparatus for laying up or twisting insulated cores in the manufacture of electric cables.

One conventional type of electric cable comprses two or more separately insulated cores or conductors covered in a common outer protective sheath. one stage in the manufacture of such cable conprises taking the requisite nLr of insulated cores wound on different drums, twisting them together, and winding them onto another drum. The layered up or twisted cores from the latter drum are then passed through an extruder in which the outer sheath is extruded over the twisted cores to form the finished cable.

In a known machine for laying up cable, insulated core is drawn from a plurality of different drums or spools outside the machine.

The machine comprises a bow-shaped guide wtich is driven to rotate about an axis which passes through the ends of the bow-shaped guide. The insulated cores pass from outside through an eye near one end of the bow, then together along the bow-shaped guide to the other end where they pass inwardly to within the bow where they are wound onto a drum. The drum is driven separately from the bow to rotate about an axis co-axial with the rotation axis of the bow, and thus draw the cable into the machine. The twisted insulated cores are fed through a traverse mechanism which moves the cores back and forth axially as the twisted cores are wound onto the drum so that the core is wound in layers.

Each time the bow guide rotates one revolution about the axis, -1 two twists are applied to the cores, a first as the cores pass from outside onto the rotating guide,, and a second as the cores pass from the bow guide inside to the traverse mechanism.

A disadvantage of this arrangement is that it requires slip rings to take power in through the bow guide to drive the drum on the traverse mechanism. The machine has to be stopped when the drum is full and then the drum has to be transferred to the machine which performs the next stage of the cable manufacturing process.

According to the present invention there is provided apparatus for twisting cores of a cable, comprising a guide, and weans for rotating the guide about an axis, a support for mounting a plurality of drums or packs of insulated cores within the guide, the guide being shaped to pass around the insulated cores on the support as the guide is rotated, and the support being mounted so as not to rotate with the guide, and weans located outside the guide for drawing core from the drums or packs outwardly in one direction and along the guide to leave the guide in the opposite direction.

Preferably the apparatus is placed next to a sheath-extruding apparatus and the twisted cores pass directly from the cable twisting apparatus to the extrusion apparatus.

In this way, the invention can provide an in-line arrangement for supplying twisted core to a sheath-extruding machine.

Preferably the insulated cores are wound in packs rather than on drums.

By using packs rather than drums it is possible to produce i t three times the amount of cable fran one loading compared with the known arrangement.

An wtodimient of the invention will now be described, by way of exarrple, with reference to the accying drawings, of which: - Figure 1 shows a diagrammatic cross-sectional view of a laying up machine in accordance with the invention; and Figure 2 shows a detail of the apparatus of figure 1 on an enlarged scale.

Referring to figure 1, apparatus for twisting insulated core comprises a hollow rotor shaft 11 formed in two sections lla and lib and in bearings 12 on stanchions 13. A bow-shaped guide 14 is rigidly se cur ed by its ends to the rotor shaft 11 between the bearings 12, thus joining the two sections together. A cradle 15 is supported from bearings 16 on the inner ends 17 of the shaft sections lla and lib. A motor (not shown) is coupled to the outer end of the shaft section 11b for rotating the shaft and guide assembly about a horizontal axis X-X in the bearings 12. The bearings 16 permit the cradle 15 to remain stationary whilst the rotor shaft and guide assembly rotate.

Means are provided for locating three packs 18, 19 and 20 of insulated core in the cradle. Usually the cores are covered in different coloured plastics insulation, for exarrple brown, blue and green/yellow for conventional 3 core cable. Each pack nay comprise a hollow frusto-conical former around which the core is wound, and a pallet base for supporting the pack. The means for locating the packs may comprise three posts 21 projecting up from the bottom of the cradle which fit inside the packs of insulated core and support the cores whilst they are being unwound. A guide 22 n-ey be fitted to the top of each post 21 for guiding the cable as it comes off the pack. Each guide 22 rises an arm twisted about a vertical axis on the post 21 at its inner end and having an eye 23 at its outer end through which the insulated core passes. The arm rotates as the core is drawn from the pack and prevents the core catching the top edge of the pack as it is drawn off, and thus preventing the core becoming tangled.

The core from the three packs pass through eyes 25 mounted on a bridge 26 extending over the cradle and through three separate holes in a. die 27 also carried by the bridge 26.

From the die 27, the three insulated cores pass into the end of the hollow shaft llb through the bearings 16 before passing out through an opening 28 in the side of the shaft. As the cores turn at the opening 28 they pass over a roller 29 which prevents abrasion.

The cores then pass along the guide 14 in the opposite direction to which they left the packs 18, 19 and 20. The cores pass through eyes 30 at intervals along the guide, with roller bearings 31 to prevent abrasion.

At the end of the bow like guide the cores pass through an opening 24 into the hollow shaft 11a. A roller 32 prevents abrasion as the cores t urn to pass along the shaft. The cores emerge from the open end of the shaft section lla-and are then passed to the sheath extrusion machine (not shown). Drive pulleys (not shown) outside the machine apply traction to the cable to pull the cable through the machine.

The bow-shaped guide 14 is rotated about the axis X-X by a 1 1 1 motor (not shown) coupled to the end of the shaft llb as the cores are drawn from the packs through the guide 14. The rotation of the bow twists the cores twice on each revolution, firstly as the cores pass fram the stationary die 27 on the cradle bridge to the rotating shaft and guide assenbly, and secondly when the cores pass frem the rotating shaft and guide assembly to the next stage of the cable making process. As the direction of the cores movement is reversed between the two positions at which the twisting is applied, the twists are applied in the same sense to the cores resulting in two twists for each revolution of the rotor shaft and guide assembly.

The use of core packs which do not have substantial centres or flanges, as is the case with drums, means that a greater length of cores can be loaded in the cradle than if drums had been used. This, in turn, means that the machine can run for a longer period of time before it has to be re-loaded.

Since it is the separate insulated cores that are loaded in the cradle it is easier to perform the loading operation than it is to perform the unloading operation with the drum carrying the twisting cores of the known machine, because each pack will weigh less than a third of the weight of the loaded drum for the same length of cores. This means that reloading the wchine can be performed more quickly and easily than unloading the conventional drum.

Although the twisted cores from the machine could be wound onto a drum for storage before subsequent use, the feature of drawing the twisted cable through the machine from outside the machine means that it is possible to incorporate the core twisting machine into an in-line arrangement with a sheath extruding machine. A conventional arrangement of weighted pulley for providing an accumulation of twisted cable between the twisting machine and the sheath extruding machine way be used to provide a reserve of twisted cable to for the extruding machine work on whilst the twisting machine is being reloaded.

Z.

A 1 claim 1. Apparatus for twisting cores of a cable, rising a guide and means for rotating the guide about an axis, a support for munting a plurality of drum or packs of insulated cores within the guide, the guide being shaped to pass around the insulated cores on the support as the guide is rotated, and the supports being mounted so as not to rotate with the guide, and means located outside the guide for drawing core from the drums or packs outwardly in one direction and along the guide to leave the guide in the opposite direction.

2. An assembly conprising apparatus according to claim placed next to a sheath-extruding apparatus wherein the twisted cores pass directly from the cable twisting apparatus to the extrusion apparatus.

3. Apparatus accordng to-claim 1 or 2 in which the insulated cores are wound in packs.

4. Apparatus according to any of the preceding claims in which the guide corprises a bowshaped guide nr secured at its ends to two coaxial shaft sections mounted in bearings.

5. Apparatus according to claim 4 in which the support conprises a cradle suspended by bearings from the inner ends of the shalf sections, so as not to rotate when the shaft sections are rotated.

6. Apparatus according to claim 5 in which the support includes posts for locating packs of insulated cores in the cradle.

7. Apparatus according to claim 5 or 6 in which the shaft sections are hollow and have openings in their side walls adjacent the ends of the bowshaped guide the shaft sections and bow-shaped guide defi nin g a path for the twisted cores in which the twisted cores pass in one of the hollow shaft sections through the bearings that support the cradle at one end pass from inside the shaft section at one end through the opening in its side wall onto the bow-shaped guide, pass from the bow-shaped guide into the shaft section at the other end through the opening in its side wall, and pass through the bearings that support the other shaft section insude the other shaft section.

8. Apparatus substantially as hereinbefore described with reference to the acconpanying drawings.

9. A method for twisting together insulated cores for an electric cable conprising drawing cores from a plurality of drLuns or packs outwardly in one direction along an axis, pasing the cores along a guide which rotates about th said axis around the drums or packs, the twisted cores leaving the guide moving outwardly from the packs or dnns along the said axis in the opposite direction to the said one direction.

10. A method substantially as hereinbefore described with reference to the acconpanying drawings.

Published 1991 at 7be Patent OMce. State House. 66/71 HighHolborn, LondonWCIR47?. Further copies maybe obtained from Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys. Newport, NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray. Kent 7 p t 1