Metal deforming – By extruding through orifice – Expressing polymetallic-layered product
Patent
1997-05-30
1999-10-12
Hail, III, Joseph J.
Metal deforming
By extruding through orifice
Expressing polymetallic-layered product
72267, 723794, B21C 2322
Patent
active
059641177
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns composite closed-end vessels, and their production by backward extrusion.
2. Discussion of Prior Art
The technique of backward extrusion involves the use of a generally cylindrical container with parallel side walls, and a ram to enter the container dimensioned to leave a gap between itself and the side walls equal to the desired thickness of the extrudate. An extrusion billet is positioned in the container. The ram is driven into a forward face of the billet and effects extrusion of the desired hollow body in a backwards direction. The forward motion of the ram stops at a distance from the bottom of the container equal to the desired thickness of the base of the extruded hollow body. Extrusion speed, the speed at which the extrudate exits from the container, is not critical but is typically in the range 50-500 cm/min. Lubrication can substantially reduce the extrusion pressure required.
SUMMARY OF THE INVENTION
In one aspect, this invention concerns a development of this technique. The invention provides a backward extrusion method for forming a closed-ended vessel which comprises providing, in a container for backward extrusion, a billet of a first extrudable metal, said billet having an axis and a forward face, and driving a ram along the axis into the forward face of the billet, body of a second extrudable material is provided in the recess, extrudable material with an adherent inner surface lining of the second extrudable material.
In another aspect, the invention provides a pressurised gas container formed by backward extrusion, which container is composed of an aluminium alloy and carries a weld bonded inner surface lining of an extrudable material.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is directed to the accompanying drawings in which:
FIGS. 1 and 2 are sectional side elevations of backward extrusion equipment according to the invention at different stages in the backward extrusion process.
FIGS. 3 and 4 are sectional side elevations of extrusion billets, each having a forward face with an axial recess therein.
FIGS. 5 and 6 are plan and side elevations of a body of a second extrudable material to be provided in the recess.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, backward extrusion equipment comprises a container 10 having cylindrical side walls to contain an extrusion billet 12, and a ram 14. The extrusion billet has a front face 16 provided with a shallow axial recess defined by a rim 18 surrounding the recess. A body 20 of a second extrudable material is provided in the recess. The ram is mounted for reciprocation in a direction 22 along the axis of the extrusion billet and the container.
FIG. 2 shows the position after the ram has been driven into the forward face of the extrusion billet. There has been formed by backward extrusion a closed-ended vessel 24 having cylindrical side walls. The vessel is composed of the first extrudable metal 26, derived from the billet 12, with a weld bonded inner surface lining of the second extrudable material 28 derived from the body 20.
If a cylindrical extrusion billet of first material had been placed in the container, and a disc of the second material placed on top of it, then the backward extrusion operation would have resulted in a closed-ended vessel in which the second material was concentrated at the forward end of the cylindrical wall, with little or none forming an interior lining at the closed backward end. To avoid this, the extrusion billet 12 is formed with an axial recess in its forward face, with the body of the second material being positioned in that recess. Preferably no part of the body of the second material stands proud of the extrusion billet. Preferably the extrusion billet includes an annular part which surrounds and extends forward of the recess in which the body of the second material is provided. Preferably the diameter of the axial recess in the forward face of the extrusion billet is substantially equal to t
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Cudney Robert Arthur
Evans John Terence
Holroyd Nigel John Henry
Hail III Joseph J.
Luxfer Group Limited
Tolan Ed
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