GB2144358A

GB2144358A - Wire swaging devices

Info

Publication number: GB2144358A
Application number: GB08320774A
Authority: GB
Inventors: Wilbert Ridd George; Kenneth Charles Hunt
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1983-08-02
Filing date: 1983-08-02
Publication date: 1985-03-06
Also published as: GB8320774D0

Abstract

A swaging device for reducing the diameter of a wire includes a plurality of rollers 11 arranged in a hyperboloidal configuration between first and second cage members (13, 14) so as to define a converging funnel-shaped assembly through which a wire (15) is passed. The rollers are rotated by a gear drive so as to swage the wire and reduce its diameter. <IMAGE>

Description

SPECIFICATION Wire swaging device This invention relates to the manufacture of conductive wire products, e.g. for use in telecommunication cables and/or power cables.

Wire products, e.g. copper or aluminium conductors for cables are conventionally manufactured by drawing the material through a number of dies.

This process suffers from the disadvantage that where a large reduction in diameter is to be provided a considerable number of die passes is required. Each draw down using a die involves the risk of wire breakage caused by balling of the wire in the die and/or by the application of excessive tension to the wire. It will be appreciated that the use of several successive dies increases the risk of breakage and a consequent halt to production whilst the wire is rethreaded.

The object of the present invention is to minimise or to overcome this disadvantage.

According to one aspect of the invention there is provided a swaging device for reducing the diameter of a wire, the device including a plurality of cylindrical rollers so disposed as to define a convergent cone through which, in use, a wire is passed, and means for rotating the rollers whereby a wire engaging the rollers is swaged to a reduced diameter.

According to another aspect of the invention there is provided a method of reducing the diameter of a wire, including swaging the wire with a plurality of rollers each disposed at an angle skew to the wire axis and each driven at a constant speed by drive means.

According to a further aspect of the invention there is provided a method of making a cable, including swaging a rod of a conductor metal to form a wire, drawing the wire through a finishing die, melt extruding a plastics material on to the wire, and stranding and laying up the coated wire into a cable.

The arrangement permits a relatively large reduction in wire diameter to be effected at a single pass. Thus the major reduction in wire diameter can be effected without the use of dies. It is only necessary to provide one or more finishing dies for the final stage of diameter reduction and for the provision of the desired crystallographic texture.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a plan view of the wire swaging device; Figure 2 is a longitudinal sectional view of the swaging device of Fig. 1; and Figure 3 is an axial view of the swaging device.

Referring to the drawings, the swaging device includes a plurality of rollers 11, typically six, supported on spindles 12 between first and second cage members 13 and 14 respectively. The rollers 11 are disposed with their axes in a converging hyperboloid arrangement so as to form a funnel shaped or approximately conical structure through which a wire 15 to be swaged is fed. The larger diameter cage 13 is provided with drive means 16 whereby, in use, the rollers 11 are rotated. The cages 13 and 14 are also capable of material rotation so as to vary the skew angle between the roller axes and the wire axis thereby defining the diameter to which the wire 15 is swaged. In some applications the entire swaging device may also be rotatable around the wire 15. Also the rollers 11 may be roughened at the inlet of the device to assist the wire feed.

In use a wire to be swaged is fed into the device by rotating the smaller cage 12 so as to reduce the skew angle of the rollers 11. The rollers 11 are then rotated and the skew angle is increased as the wire is fed through the device until the desired reduction in wire diameter is obtained. After this initial setting-up procedure wire drawing or swaging may then be performed on a continuous basis. In some applications, a lubricant may be employed to improve the processing rate.

The wire diameter reduction provided by the swaging process is significantly greater than that obtainable by a single die pass. Thus die drawing provides a diameter reduction of about 10% whereas using the arrangement described we have achieved reductions in copper wire diameter from 10mm to 5mm, i.e. a 50% reduction, with a 30mm roller contact length.

The swaging process advances the wire through the rollers, the advance rate being dependent on the roller diameter and skew angle. For example, with a skew angle of 8 using 7mm diameter rollers the wire advance rate is 1.9mm/roll reduction.

For wire bar end swaging the bar should be pushed into the device with some assistance from the rollers, but for swaging lengths of roll we have found pulling from the exit end more effective.

As with die drawing the wire may require intermediate annealing after each stage of diameter reduction.

The arrangement may be employed on a variety of wire materials, but it is particularly effective with the ductile materials such as copper and aluminium or alloys of these metals.

The swaging device is particularly effective in the manufacture of conductor wires for power or telecommunications cables. In such an application the swaging device may be arranged in tandem with an extruder to provide a continuous supply of plastics insulated wire for subsequent cabling operations. For this purpose copper or aluminium rod is swaged down to a diameter slightly larger than the required conductor size and is then drawn through one or more finishing dies prior to feeding into the head of a melt extruder. The coated wire from the extruder may then be stranded and laid up into a cable form which is then provided with an external sheath to form the finished cable product.

The device may also find application for swaging sintered, metal powder bars to consolidate or increase their density prior to rolling or drawing. For example tungsten and molybdendum metal products, produced by a powder-metallurgy route, cannot readily be rolled or drawn before swaging to decrease their porosity and improve their ductility.

Claims

1. A swaging device for reducing the diameter of a wire, the device including a plurality of cylindrical rollers so disposed as to define a convergent cone through which, in use, a wire is passed, and means for rotating the rollers whereby a wire engaging the rollers is swaged to a reduced diameter.

2. A swaging device as claimed in claim 1, wherein the skew angle between the rollers and the longitudinal axis of the device is adjustable.

3. A swaging device as claimed in claim 1 or 2, wherein the rollers are provided with roughened surfaces.

4. A wire swaging device substantially as described herein with reference to the accompanying drawings.

5. A method of reducing the diameter of a wire, including swaging the wire with a plurality of rollers each disposed at an angle skew to the wire axis and each driven at a constant speed by drive means.

6. A method as claimed in claim 5, wherein the wire is copper, aluminium or an alloy thereof.

7. A method of reducing the diameter of a wire, which method is substantially as described herein with reference to the accompanying drawings.

8. A wire or wire product swaged by a method as claimed in claim 5, 6 or 7.

9. A power or telecommunications cable incorporating a wire or wire product as claimed in claim 8.

10. A method of making a cable, including swaging a rod of a conductor metal to form a wire, drawing the wire through a finishing die, melt extruding a plastics material on to the wire, and stranding and laying up the coated wire into a cable.

11. A power or telecommunications cable made by the method of claim 10.