According to one aspect of the present invention machining means are positioned to receive feedstock from the feed reel means and to discharge machined feedstock to the circumferentially extending groove, with the machining means being arranged to remove at least a surface layer from the feedstock and form a circular cross-section dimensioned as a close fit within the circumferentially extending groove.

Preferably the machining means include a centreless lathe.

Alternatively, the machining means includes a shaving head.

Desirably, drive motors for the feed reel, the machining means and the wheel are electronically linked such that the speed of the feed reel and the speed of the machining means are adjusted in accordance with the speed of the wheel.

According to another aspect of the present invention, there is provided a method of production of a continuous extrusion product including supplying feedstock of substantially generally circular cross-section from a feed reel to machining means, machining the feedstock to remove at least a surface layer and form a circular cross section feed dimensioned as a close fit within the circumferentially extending groove, feeding the machined feedstock directly from the machining means to the circumferentially extending groove and driving the wheel carrying the machined feedstock around in the circumferentially extending groove to contact an abutment and discharge through a die to form an extruded product.

Preferably, the feedstock is of aluminium.

Alternatively the feedstock is copper.

Desirably, the machining means operates to a tolerance of +/-0. 1mm on a typical diameter of 12.7mm of feedstock.

In one embodiment, the extrusion plant includes, in in-line series, a feed reel means, machining means, a continuous extrusion machine and a product take-up reel.

The feed reel means includes an electric drive motor and is arranged to deliver aluminium feedstock in the form of an approximately circular cross-section aluminium wire rod through guide rollers to a centreless lathe having an electric drive motor.

The centreless lathe is positioned closely adjacent the continuous extrusion machine and delivers machined feedstock directly to a parallel sided circumferentially extruding groove formed on the rotating wheel of the continuous extrusion machine driven by an electric motor.

The continuous extrusion machine discharges extruded product from a die connected through a passage in a die body mounted adjacent an abutment extending into the circumferentially extending groove and delivers the extruded product to the product take-up reel driven by an electric motor.

Respective electronic speed control means are associated with each of the electric motors with the speeds at the feed reel, of the centreless lathe and at the take- up reel being electronically linked to the speed of rotation of the rotating wheel of the continuous extrusion machine.

In operation, aluminium feed stock with a nominal diameter to +/-0.2mm, or 4% (i. e. approximately 2mm) greater than the width, axially of the wheel, of the groove, is fed from the feed reel to the centreless lathe which is set to machine the feedstock to a diameter corresponding to the width of the groove thereby removing a surface layer from the feedstock. In removing the surface layer, surface impurities are removed and

feedstock with a clean, non-oxidised, surface is delivered directly to the groove without intervention of feed rollers liable to cause distortions in the feedstock whilst at the same time ensuring substantially constant forces arising at the walls of the groove between the feedstock, which has been machined to close tolerances, and the walls of the groove. This reduces any tendency toward irregular feed of the feedstock around the groove toward the abutment and thus enhances the constancy of the product quality arising from extrusion as well as avoiding problems with oxidation and/or surface imperfections inherent in separating the two processes.

It will be apparent that metals other than aluminium, such as copper, may be utilised as feedstock and that the extrusion product may be delivered at a controlled rate as cut-to-length bar stock rather than being wound on to a take-up reel.