Kobe Steel, Ltd.

Yuuzi Nakahara

Yoshihiro Yamaguchi

Tomiharu Matsushita

Tatsuo Yamasaki

Hideaki Ide

A hydrostatic extrusion method and apparatus for the extrusion of tubes is disclosed wherein the simplified structure of the nose or tip portion of the billet and the cooperating surfaces of the die defining the die cavity and those of the mandrel facilitate an improved initial sealing among the associated surfaces of the die, billet and mandrel. Such an initial sealing is effected between such interfaces of the members and billet at a point which is located substantially rearwardly from the position at which the actual extrusion to the final tubular configuration occurs between the bearing portion of the die and the cooperating sizing portion of the mandrel. Such structure and method permits the extrusion of tubes having walls of asymmetric or non-circular configurations in cross section, even those of complex configurations. In order to further enhance the efficacies of the present invention, the mandrel is provided with a head portion which may be replaced, or exchanged as desired, and a position-aligning member is associated with the mandrel in order to maintain the proper orientation of the mandrel relative to the die. The mandrel may also have a specifically designed configuration in order to provide the inner surface of the tube extruded with a gloss finish.

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Osaka, Japan

Yuuzi Nakahara