GB2189728A - Coated wire manufacturing method - Google Patents

Abstract

A method for continuously manufacturing an aluminium-coated wire involves unwinding a core wire a and two aluminium coating wires b and b' from respective pay-off reels 1, 2 and 2'; straightening and cleaning the wires during the unwinding step; extruding the wires through an extruding chamber 7 to apply the coating wires b, b' on the surface of the core wire a; the coating wires, prior to the extruding step being passed over a rotating wheel and a narrow channel disposed within the extruding chamber 7 where they are softened by the frictional heat generated between the coating wires and the rotating wheel; cooling the extruded product wire ab; and winding the coated wire ab on a take-up reel 10. <IMAGE>

Description

SPECIFICAION Coated wire manufacturing method This invention relates two a method for manufacturing a metal-coated wire, and particularly but not exclusively to a method for continuously applying a coating of aluminum alloy on the surface of a high strength-alloy wire.

Such coated wires are used for example, in moth-proofgauzewhere it is necessary to coat the wire in orderto prevent an early reduction of its life due to surface oxidisation.

Known methods for producing an aluminum alloy-coated wirefor a moth-proof gauze either involve forming a composite billet including a coated core and directly extruding said billet to produce a wireorcasting a square bar shaped core and attaching around said core two extruded alloy channel shaped coatings. These conventional methods are not continuously carried out so they suffer from several disadvantages. With the first method, there isa limitation on the billet size depending upon the capacity ofthe extruder. With the second method, where the core is made of an aluminum alloy, the joint between the core andthe coating alloy is not always properly made when the billet is continuously extruded. Thus, with both methods, it is impossible to produce a sufficient length of wire.

In order to produce a sufficient length ofwire, therefore, a large capacity extruder has to be used, in which case, a substantial part of the billet is also lost as a dead zone, with the result that work efficiency and production are very iow.

In the second method, on the other hand, a circular wire is produced from an initially square shaped core (a) and coatings (b) and (b') as shown in Figure 4with the result that the coating tends not to be uniform which is unacceptable. Furthermore, the core material may be exposed through the joints between the two coatings due to the weakness of said joints.

Since this method is non-continuous, it is also necessaryforthe equipment to be large, in order to produce a sufficient length of wire.

Furthermore, it suffers from the disadvantage of high energy losses in each step of the process and thereby a lowwork rate.

It is an object of the present invention therefore to provide a method for continuously manufacturing coated wire which improves productivity and workabiiity compared with these prior art methods.

According to the invention, there is provided a method for continuously manufacturing a metal coated wire comprising feeding a core wire and at least one metal coating wire through an extruder where the or each coating wire is applied to the core wire, the or each coating wire being pre-heated prior to reaching the extruder by passing itthrough/overa rotating wheel where it is heated and softened or melted due to the functional heat generated.

Preferably, the or each coating wire is fed through a narrow slot adjacent the rotating wheel to generate the required level of friction to heat the or each wire up to cause it to melt.

Preferably, the or each wire is each unwound from a respective pay-off reel and straightened and cleaned during the unwinding step, the coated wire being cooled after it leaves the extruder and wound onto a take-up reel.

A preferred method ofthe invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure lisa schematic view illustrating the process of the present invention; Figure 2 is a perspective view of an aluminium-coated wire made bythe method of the invention.

Figure 3 is a cross-section along the lines A-A in Figure 2; and Figure 4 is a schematic cross-sectional view of a prior art process.

Referring to the drawings, there is shown in Figure 1 a core wire (a) wound on an intermiediate pay-off reel 1. Two coating wires (b) and (b'), preferably of aluminium, arewound on respective pay-off reels 2 and 2' disposed on either side of the pay-off reel 1 and spaced therefrom.

The wires (a), (b) and (b') are unwound simultaneously.

After leaving the reel 1, the unwound core wire (a) passes through a straightening device 3 and through a pre-treating device 5 where the surface of said wire has any oxides or other contaminants removed therefrom to leave the wire with a rough exterior which provides an effective bonding surfaceforthe coating layer to be applied subsequently.

The pre-treated core wire (a) then passes to chamber 7 of an extruderwhere it is coated with the coating wires (b) and (b').

The coating wires (b) and (b') from the pay-off reels 2 and 2' pass through straightening devices 4 and 4' and then through respective pre-cleaning units 6 and 6' where their surfaces have any oxides or other contaiminants removed therefrom. After this, the coating wires (b) and (b') pass through respective guide roller assemblies A onto a rotating wheel disposed within the extruding chamber 7.

The wheel associated with the extruding chamber 7 has two grooves on it th rough which the coating wires (b, b') pass while at the same time being fed through a narrow groove where they are heated to about400-6000C as a result of the heat generated by the friction between each coating wire and the wheel, so they melt or soften to a creamy consistency and enterthe extruding chamber 7, maintained at a proper extruding temperature of about 300 to 500'C where the core wire (a) is coated with the coating wires (b) and (b') during the extrusion thereof as it passes through the chamber 7.

The extruded coated wire (ab) is pulled by tension means9fromtheextrudingchamber7through cooler 8, which may be of the shower type, and it is then finallywound on take-up reel 10.

In the above-mentioned process, the core wire (a) and the coating wires (b) and (b') are continuously unwound from their respective pay-off reels 1,2 and 2' and they are then extruded as they pass through each process line after being cleaned. Thus, the manufacture of the finished wire can be automatically and continuously carried out, so that the rate of production is fast and the management of the process is easy and convenient. In addition, there is little loss of the wire materials and the aluminum coating on the wire is uniform. Another advantage of the method of the invention is that there is no need to manufacture a billet orto use a heat rolling process, as is required in the prior art methods.

Claims (5)

1. A method for continuously manufacturing a metal coated wire comprising feeding a core wire and at least metal coating wire through an extruder where the or each coating wire is applied to the core wire, the or each coating wire being pre-heated prior to reaching the extruder by passing it through/over a rotating wheel where it is heated and softened due to the frictional heat generated.

2. A method as claimed in claim 1 wherein the or each wire is unwound from a respective pay-off reel and straightened and cleaned during the unwinding step, the coated wire being cooled after it leaves the extruder and wound onto atake-up reel.

3. A method as claimed in claim 1 orclaim2 wherein the or each coating wires are aluminium or aluminium alloy.

4. A method as claimed in any one ofthe proceding claims wherein the extruder includes a chamber through which the wires are passed to apply the or each coating wire to the core wire.

5. A method for continuously manufacturing a metal coated wire substantially as herein described with reference to Figures 1 - 3 of the accompanying drawings.