Method of manufacturing compound billets for hydrostatic extrusion

Abstract

In the manufacture of compound billets composed of two or more different metals for use in hydrostatic extrusion, care must be exercised to see whether or not products possessing a predetermined compound status are produced from the compound billets by means of the hydrostatic extrusion process. The compound billets manufactured through the method of this invention do not, in the hydrostatic extrusion process, possess the usual defects caused by discrepancies between the mechanical properties of a plurality of different metallic materials constituting the billets, especially, and in particular, it is true that the compound billets are free from defects caused by surface slip taking place between the surfaces of the internal and external layer materials of the compound billet of the different metallic materials, and the method according to the present invention is characterized in that the formation of the nose part is undertaken by plastic forming of the same, such as roll forming and swazing, from the outside while maintaining an interior condition wherein air is expelled from the space formed between the contacting surfaces of the different metallic materials. As a result, the materials are mechanically bonded together and the surface areas of the materials of the billet at the deformed nose portion to be presented to the die are equal and it becomes possible to carry out a hydrostatic extrusion of the compound materials under a combination of different metallic materials covering an extremely wide selection.

Dependencies are inferred from the claim text.