GB2074827A

GB2074827A - Improved method of heat treating wire

Info

Publication number: GB2074827A
Application number: GB8111992A
Authority: GB
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1980-04-22
Filing date: 1981-04-15
Publication date: 1981-11-04
Also published as: GB2074827B

Abstract

Wire (1) is continuously heated by passing it over two or more electrically conductive pulleys (2, 3, 4) as it travels in the direction of its length and causing an electric current to flow along the wire. Streams of inert gas (5) are directed between the wire and the pulleys in order to extinguish or inhibit formation of arcs therebetween. The gas may be supplied through holes in the surfaces of the pulleys. <IMAGE>

Description

SPECIFICATION Improved method of treating wire This invention relates to continuous heating of a bare flexible elongate member of electrically conductive material such as wire, strip, tape or the like, all such bare flexible elongate electrically conductive members hereinafter, for convenience, being included in the generic term "wire", and is especially, but not exclusively, concerned with the continuous annealing of wire.

In a known method of continuously heating wire, an electric current is passed through the wire in order to raise its temperature, the current being induced in the wire electromagnetically or being caused to flow in the wire by maintaining a potential difference between two spaced points on the wire. In each case, it is necessary to form a continuous flow path for the current and this is often achieved by passing the wire over spaced electrically conductive pulleys. It has been found that in some circumstances arcing occurs between the wire and the conductive pulleys, especially where the wire approaches and leaves the conductive pulleys. This arcing causes rapid wear of the circumferential surface of the conductive pulleys and also causes damage to the surface of the wire itself.

It is an object of the present invention to provide an improved method of continuously heating wire by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, in which method risk of arcing occuring between the wire and a pulley is substantially reduced.

According to the invention, in the improved method of continuously heating wire, in the vicinity of the position of contact between the wire and at least one, and preferably each, of the pulleys at least one stream of inert gas is directed between the wire and the pulley to extinguish or inhibit formation of an are therebetween.

The invention is especially, but not exclusively, applicable to the so called method of in-line annealing of wire in which a wire is caused to travel between two electrically conductive pulleys, one of which is maintained at a potential substantially higher than that of the other, so that a current flows from one pulley, through the wire, to the other pulley to heat the wire.

Preferably, the or each stream of inert gas is directed between the wire and an electrically conductive pulley at the positions at which the wire approaches and/or leaves the pulley.

Alternatively, or additionally, streams of inert gas may be directed between the wire and pulley through at least one aperture in the circumferential surface of the pulley. In one embodiment of the invention the inert gas is directed between the wire and the pulley, through at least one aperture in the circumferential surface of the pulley, at the positions at which the wire approaches and/or leaves the pulley.

In another embodiment of the invention, the inert gas is fed down a hollow shaft which carries the pulley and which communicates with the apertures in the circumferential surface of the pulley.

The invention also includes apparatus for use in the method of continuously heating wire as hereinbefore described.

The invention will be further illustrated by a description, by way of example, of an in-line wire annealing process with reference to the accompanying drawings, in which: Figure 1 illustrates, d.iagrammatically the apparatus employed in the in-line wire annealing process; Figure 2 illustrates one form of conductive pulley through which the air may be introduced, and Figure 3 illustrates another form of conductive pulley for this purpose.

Referring to Figure 1, wire 1 travelling from a wire-drawing machine passes over, and electrically contacts, an earthed electrically conductive pulley 2.

The wire continues along its path until it passes over, and electrically contacts, another electrically conductive pulley 3 which is maintained at a higher potential than the pulley 2. An electric current flows between the pulley 3 and the pulley 2 via the wire 1 and is such that the heating effect it causes in the wire is sufficient to heat the wire to its annealing temperature. On leaving pulley 3 the wire travels to another electrically conductive pulley 4 which is earthed. Again the wire electrically contacts the pulley 4 and an electric current flows between the pulley 3 and the pulley 4 via the wire 1. The heating effect caused by the flow of such a current in the wire is sufficient to complete the annealing process. On leaving the pulley 4, the wire passes to other equipment for further processing if required.A fan or other suitable blowing device directs streams of air 5 between the wire and each pulley 2, 3 or 4 at each of the positions at which the wire approaches or leaves a pulley to extinguish, orto inhibit the formation of, any electrical arcs between the wire 1 and the pulley.

The conductive pulley shown in Figure 2 may be used in place of any of each of the pulleys 2,3 or 4 illustrated in Figure 1. Open-ended pulleyS, formed by an endplate 7 and a surface 8 with apertures 9, is rotatable about an axis defined by shaft 10 which is centrally attached to end plate 7.

Rotation of the pulley 6 directs streams 11 of air outwardly through apertures 9, so that when wire 1 passes over apertures 9 air is directed to those places at which arcing is likely to occur thereby extinguishing, or inhibiting the formation of, any arcs between the wire and the pulley.

Hollow pulley 12 as shown in Figure 3 has a further endplate 13 thereby forming a substantially enclosed internal space which is attached to, and defines the axis of rotation of, pulley 12.

In operation, air fed through bore 14 enters the internal space and then passes out through aperture 16 of pulley 12to produce streams 17 of airwhich extinguish, or inhibit formation of, any electric arcs between the wire 1 and pulley 12.

1. A method of continuously heating wire by

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved method of treating wire This invention relates to continuous heating of a bare flexible elongate member of electrically conductive material such as wire, strip, tape or the like, all such bare flexible elongate electrically conductive members hereinafter, for convenience, being included in the generic term "wire", and is especially, but not exclusively, concerned with the continuous annealing of wire. In a known method of continuously heating wire, an electric current is passed through the wire in order to raise its temperature, the current being induced in the wire electromagnetically or being caused to flow in the wire by maintaining a potential difference between two spaced points on the wire. In each case, it is necessary to form a continuous flow path for the current and this is often achieved by passing the wire over spaced electrically conductive pulleys. It has been found that in some circumstances arcing occurs between the wire and the conductive pulleys, especially where the wire approaches and leaves the conductive pulleys. This arcing causes rapid wear of the circumferential surface of the conductive pulleys and also causes damage to the surface of the wire itself. It is an object of the present invention to provide an improved method of continuously heating wire by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, in which method risk of arcing occuring between the wire and a pulley is substantially reduced. According to the invention, in the improved method of continuously heating wire, in the vicinity of the position of contact between the wire and at least one, and preferably each, of the pulleys at least one stream of inert gas is directed between the wire and the pulley to extinguish or inhibit formation of an are therebetween. The invention is especially, but not exclusively, applicable to the so called method of in-line annealing of wire in which a wire is caused to travel between two electrically conductive pulleys, one of which is maintained at a potential substantially higher than that of the other, so that a current flows from one pulley, through the wire, to the other pulley to heat the wire. Preferably, the or each stream of inert gas is directed between the wire and an electrically conductive pulley at the positions at which the wire approaches and/or leaves the pulley. Alternatively, or additionally, streams of inert gas may be directed between the wire and pulley through at least one aperture in the circumferential surface of the pulley. In one embodiment of the invention the inert gas is directed between the wire and the pulley, through at least one aperture in the circumferential surface of the pulley, at the positions at which the wire approaches and/or leaves the pulley. In another embodiment of the invention, the inert gas is fed down a hollow shaft which carries the pulley and which communicates with the apertures in the circumferential surface of the pulley. The invention also includes apparatus for use in the method of continuously heating wire as hereinbefore described. The invention will be further illustrated by a description, by way of example, of an in-line wire annealing process with reference to the accompanying drawings, in which: Figure 1 illustrates, d.iagrammatically the apparatus employed in the in-line wire annealing process; Figure 2 illustrates one form of conductive pulley through which the air may be introduced, and Figure 3 illustrates another form of conductive pulley for this purpose. Referring to Figure 1, wire 1 travelling from a wire-drawing machine passes over, and electrically contacts, an earthed electrically conductive pulley 2. The wire continues along its path until it passes over, and electrically contacts, another electrically conductive pulley 3 which is maintained at a higher potential than the pulley 2. An electric current flows between the pulley 3 and the pulley 2 via the wire 1 and is such that the heating effect it causes in the wire is sufficient to heat the wire to its annealing temperature. On leaving pulley 3 the wire travels to another electrically conductive pulley 4 which is earthed. Again the wire electrically contacts the pulley 4 and an electric current flows between the pulley 3 and the pulley 4 via the wire 1. The heating effect caused by the flow of such a current in the wire is sufficient to complete the annealing process. On leaving the pulley 4, the wire passes to other equipment for further processing if required.A fan or other suitable blowing device directs streams of air 5 between the wire and each pulley 2, 3 or 4 at each of the positions at which the wire approaches or leaves a pulley to extinguish, orto inhibit the formation of, any electrical arcs between the wire 1 and the pulley. The conductive pulley shown in Figure 2 may be used in place of any of each of the pulleys 2,3 or 4 illustrated in Figure 1. Open-ended pulleyS, formed by an endplate 7 and a surface 8 with apertures 9, is rotatable about an axis defined by shaft 10 which is centrally attached to end plate 7. Rotation of the pulley 6 directs streams 11 of air outwardly through apertures 9, so that when wire 1 passes over apertures 9 air is directed to those places at which arcing is likely to occur thereby extinguishing, or inhibiting the formation of, any arcs between the wire and the pulley. Hollow pulley 12 as shown in Figure 3 has a further endplate 13 thereby forming a substantially enclosed internal space which is attached to, and defines the axis of rotation of, pulley 12. In operation, air fed through bore 14 enters the internal space and then passes out through aperture 16 of pulley 12to produce streams 17 of airwhich extinguish, or inhibit formation of, any electric arcs between the wire 1 and pulley 12. CLAIMS

1. A method of continuously heating wire by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, wherein, in the vicinity of the position of contact between the wire and at least one of the pulleys, at least one stream of inert gas is directed between the wire and the pulley to extinguish or inhibit formation ofan arc therebetween.

2. A method of continuously heating wire, by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, wherein, in the vicinity of the positions at which the wire approaches and/or leaves at least one of the pulleys, at least one stream of inert gas is directed between the wire and the pulley to extinguish or inhibit formation of an are therebetween.

3. A method of continuously heating wire, by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, wherein, in the vicinity of the positions of contact between the wire and at least one of the pulleys, at least one stream of inert gas is directed between the wire and the pulley through at least one aperture in the circumferential surface ofthe pulley.

4. A method as claimed in Claim 2 or 3, wherein streams of inert gas are directed between the wire and the pulley through a plurality of apertures mutually spaced around the circumferential surface ofthe pulley.

5. A method as claimed in Claim 3 or 4, wherein the stream or streams of inert gas is or are directed between the wire and the pulley at the position(s) at which the wire approaches and/or leaves the wire.

6. A method as claimed in any one of Claims 3 to 5 wherein the inert gas is fed to the aperture or apertures through a bore in a shaft on which the pulley is mounted.

7. Apparatus for continuously heating wire by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, wherein at least one of the pulleys has at least one aperture in a circumferential surface and wherein means is provided for directing inert gas radially through said aperture or apertures.

8. Apparatus according to Claim 7, wherein means is provided for directing the inert gas to, and radially outwardly through, said aperture or apertures.

9. Apparatus as claimed in Claim 8, wherein the or each pulley is carried by a shaft having a bore which communicates with said aperture or apertures in the circumferential surface of the pulley and through which bore inert gas may be fed.

10. Apparatus for continuously heating wire by passing an electric current therethrough as the wire travels in the direction of its length between at least two spaced electrically conductive pulleys, wherein means is provided to direct at least one stream of inert gas between the wire and the pulley in the vicinity of the positions at which the wire approaches and/or leaves at least one of the pulleys to extinguish or inhibit formation of an arc therebetween.

11. A method of continuously heating wire substantially as hereinbefore described with reference to Figure 1.

12. Apparatus for continuously heating wire substantially as hereinbefore described with reference to Figure 1.

13. Apparatus for continuously heating wire substantially as hereinbefore described with reference to and as illustrated in Figure 2 or Figure 3.