Abstract: This invention relates to a method and an apparatus for lubricated forward extrusion of metals and alloys with radial forward removal of an outer shell or sheath. The method according to the invention consists of forming a gap in the form of a plane or slightly truncated cone-shaped circular outer ring having a constant thickness (j) and span (h) and open to the atmosphere between the end of the container adjacent to its bore and the assembly of extrusion tools situated opposite thereto. To facilitate the formation and especially the extraction of the outer shell, the extrusion apparatus comprises several knives situated in the above described gap, having their cutting edge directed towards the axis of the container and dividing the outer shell into as many "petals" in the course of extrusion.

Abstract: A method for the production of a composite hollow body formed of aluminum alloys and composed of two layers having differing structure. One layer of the hollow body is intended to operate in contact with a mobile surface and is produced by extruding a mixture of particles of a hypereutectic silicon alloy having fine grains and an addition product. The other layer is selected from among alloys having certain particular properties and has the structure of a cast and wrought product. The present method particularly consists of the step of joining the two layers by coextrusion on a mandrel in an inverse extrusion press. The composite hollow bodies so produced are used in the production of linings for internal combustion engines or for jacks.