Process for extruding a metal tube with inwardly thickened end portions

Abstract

A process for cold extrusion forming a metal tube with thickened end portions, including positioning a short, tubular blank in a die having an extrusion die throat, and pushing the blank through the die throat with a punch. The punch is formed with co-axial extension portions of successively smaller diameter. Thus, the first extension portion is closely fitted within the blank, while the second extension portion is aligned within the die throat as the punch end pushes the blank towards and through the die throat to thereby form the tube lead end thickened end portion. Further pushing of the blank by the punch takes place while the first extension is aligned with the die throat to thereby extrude the relatively thin wall middle portion of the tube. Next, the punch is removed, and a second blank is inserted within the die against the trailing end of the first blank. The punch is reinserted to press the second blank, which in turn pushes the first blank through the die throat while the third extension is positioned in the die throat to form an inwardly extending annular ring-like portion within the metal tube. Thereafter, further pressure by the punch, while the second die extension is again aligned within the die throat, simultaneously extrudes the metal tube trailing end thickened portion and simultaneously, the lead end thickened portion on the tube produced from the second blank.