GB2107234A - Extrusion of metal - Google Patents

Abstract

In a continuous friction-actuated process for the extrusion of metal in which a passageway is formed between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects at least one rotary milling cutter is continuously operated in the opening of the wheel groove at a position outside the passageway to free its edges of adherent particles of flash. <IMAGE>

Description

SPECIFICATION Extrusion of metal This invention relates to the continuous frictionactuated extrusion of metal, and more especially to the extrusion of particulate copper feedstock.

In our British prior Patent Applications 8005498 and 8104910 (Serial No. 2069389A) we have described and claimed a continuous friction-actuated extrusion process comprising forming a passageway extending from an entry end to an exit end between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects while rotating the wheel in such a direction that those surfaces of the passageway constituted-by the groove travel from the entry end towards the exit end, feeding metal into the passageway at the entry end and extruding it from the passageway through at least one die orifice located in or adjacent to an abutment member extending across the passageway at the exit end thereof characterised by the facts that the abutment member (instead of being large enough to block the end of the passageway) is of substantially smaller cross-section than the passageway and leaves a substantial gap between the abutment member and the groove surface and that the metal is allowed to adhere to the groove surface, whereby a substantial proportion of the metal (as distinct from the inevitable leakage of flash through a working clearance) extrudes through the clerarance and that this metal remains as a lining in the groove to re-enter the passageway at the entry end while the remainder of the metal extrudes through the die orifice(s).

This technique abolishes the formation of flash at the base of the wheel groove by converting it to a useful coating, but flash is still formed at the longitudinal joint between the first and second members and in part carried away along the edges of the wheel groove; this flash is difficult to remove completely by the use of conventional knives.

In accordance with one aspect of the present invention a continuous friction-actuated process for the extrusion of metal comprising forming a passageway extending from an entry end to an exit end between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects while rotating the wheel in such a direction that those surfaces of the passageway constituted by the groove travel from the entry end towards the exit end, feeding metal into the passageway at the entry end and extruding it from the passageway through at least one die orifice located in or adjacent to an abutment member extending across the passageway at the exit end thereof, the abutment member being of substantially smaller cross-section than the passageway so as to leave a substantial gap between the abutment member and the groove so that a substantial proportion of the metal extrudes through the clearance between the abutment and the groove surface and adheres to the rotating wheel to form a lining in the groove which also reenters the passageway at the entry end while remainder of the metal extrudes through the die orifice(s) is distinguished by continuously operating at least one rotary milling cutter in .the opening of the wheel groove at a position outside the said passageway to free its edges of adherent particles of flash.

In accordance with another aspect of the invention, cqntinuous friction-actuated extrusion apparatus comprising a passageway extending from an entry end to an exit end between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects, means for rotating the wheel in such a direction that those surfaces of the passageway constituted by the groove travel from the entry end towards the exit end, and at least one die orifice located in or adjacent to an abutment member extending across the passageway at the exit end thereof for extrusion of material from the passageway and in which the abutment member-(instead of being large enough to block the end of the passageway) is of substantially smaller cross-section than the passageway and leaves a substantial gap between the abutment member and the groove surface through which a substantial proportion of the metal will extrude in use to remain as a linking in the groove to re-enter the passageway at the entry end is distinguished by at least one rotary milling cutter in the opening of the wheel groove at a position outside the said passageway.

We prefer to use a single cutter that is a clearance fit in the opening of the groove, but separate cutters operating on one edge each could be used if preferred. We prefer to precede the rotary cutter by a conventional knife to remove the greater part of the flash. For extra security, two rotary cutters working in succession could be used, or a further (or a) knife cutter could be located beyond the rotary milling cutter.

When extruding particulate copper, no special precautions are needed to secure adequate adhesion of the metal to the groove surface; for copper rod feedstock, the technique of our Application No.8222612 (Serial No. ) is preferably used; and for some other metals careful choice of wheel and tooling materials and dimensions may be necessary.

The invention will be further described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic cross-section of a preferred extrusion machine in accordance with the invention; and Figures 2 to 4 are fragmentary enlarged crosssectional views along the lines 11--11. Ill-Ill and lV-IV respectively.

In the friction-actuated extrusion machine shown in Figure 1 a wheel 1 is formed with a groove 2, that forms three sides of the extrusion passageway 3. The fourth side is formed by an assembly comprising a shoe 4 and a semi-circular abutment member 5 (see Figure 2).

An extrusion orifice 6 is formed in-a die member 7 (which is preferably a separate component, though it might be integral with either the abutment member or the shoe). Alternatively the die orifice may be formed tangentially through the abutment itself.

A fixed knife cutter 8 and a rotary milling cutter 9 are located beyond the abutment member 5 so as to act in succession. Cross-sectional views of the cutters are shown in Figures 3 and 4 respectively.

In operation, the wheel 1 is rotated and particulate copper is fed into the passageway. A friction-actuated extrusion process results with a continuous wire being extruded from the extrusion orifice 6. At the same time, the wheel 1 is coated with a layer of copper 10 which emerges through the clearance y, between the abutment member 5 and the groove 2, and adheres to the surface of the wheel to re-enter the passageway at the entry end 12.

This technique abolishes the formation of flash at the base of the groove 2 by converting it to a useful coating, but flash is still formed at the longitudinal joint between the abutment member 5 and the walls of the groove 2 and is in part carried away along the edges of the groove.

In order to remove this flash before it can re enter the extrusion passageway 3, a fixed knife cutter 8 is initially located beyond the abutment member 5. This knife cutter removes most of the heavy flash adhered to the outer edges of the groove 2. However, the ability of the knife cutter to remove flash from the lower parts of the walls is limited. In accordance with the invention, a rotary milling cutter 9 is provided; this is located beyond the position of the knife.

The milling cutter is a side and face type; the teeth are profiled to match the cross-section of the coated groove as shown in Figure 4.

As the wheel 1 rotates past the rotary flash cutter 9, the remaining pieces of flash not removed by the knife cutter 8 are stripped from the edges of the groove 2 and any oxide layer may also be removed from the coating in the base of the groove.

In the preferred embodiment, the clearance given between the teeth 11 of the rotary flash cutter and the walls of the groove is 21 1 mm in total.

In one particular example of the apparatus shown in the drawings, the wheel 1, of diameter 300 mm, was rotated at about 10 rpm and particulate copper, with an average particle size of 2-3 mm, was fed into the passageway 12. The flash, formed at the abutment member 5, which was not removed by the knife cutter 8 was removed by the rotary milling cutter 9, which was 15 cm in diameter and rotated at no more than 1000 rpm. The twenty four teeth on the rotary milling cutter 9 were each 11 mm wide.

Flash removed in the operation of the present invention will usually be in smaller more compact particles than flash removed with a knife, and therefore more suitable for immediate re-cycling (with an intermediate deoxidation step, if necessary).

Claims (6)

1. A continuous friction-actuated process for the extrusion of metal comprising forming a passageway extending from an entry end to an exit end between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects while rotating the wheel in such a direction that those surfaces of the passageway constituted by the groove travel from the entry towards the exit end, feeding metal into the passageway at the entry end and extruding it from the passageway through at least one die orifice located in or adjacent to an abutment member extending across the passageway at the exit end thereof, the abutment member being of substantially smaller cross-section than the passageway so as to leave a substantial gap between the abutment member and the groove so that a substantial proportion of the metal extrudes through the clearance between the abutment and the groove surface and adheres to the rotating wheel to form a lining the groove which also reenters the passageway at the entry end while the remainder of themetalextrudes through the die orifice(s) distinguished by continuously operating at least one rotary milling cutter in the opening of the wheel groove at a position outside the said passageway to free its edges of adherent particles of flash.

2. A process as claimed in Claim 1 distinguished by using a single milling cutter that is a clearance fit in the opening of the groove.

3. Continuous friction-actuated extrusion apparatus comprising a passageway extending from an entry end to an exit end between an arcuate first member and a second member in the form of a wheel having a circumferential groove formed in its peripheral surface into which groove the first member projects, means for rotating the wheel in such a direction that those surfaces of the passageway constituted by the groove travel from the entry end towards the exit end, and at least one die orifice located in or adjacent to an abutment member extending across the passageway at the exit end thereof for extrusion of material from the passageway and in which the abutment member (instead of being large enough to block the end of the passageway) is of substantially smaller cross-section than the passageway and leaves a substantial gap between the abutment member and the groove surface through which a substantial proportion of the metal will extrude in use to remain as a lining in the groove to re-enter the passageway at the entry end, distinguished by at least one rotary milling cutter in the opening of the wheel groove at a position outside the said passageway.

4. Apparatus as claimed in Claim 3 having a single milling cutter that is a clearance fit in the opening of the groove.

5. A continuous friction-actuated extrusion process substantially as described with reference to the drawings.

6. Continuous friction-actuated extrusion apparatus substantially as described with reference to and as shown in the drawings.