A cold forging process for producing thin-walled hollow balls from tube using a plastic insert

Abstract

AbstractThis paper investigates a cold forging process for producing hollow balls made of an aluminium alloy. The forging with an outside diameter of 30 mm is formed from a tube section with a 2-mm wall thickness. Preliminary tests have shown that in traditional die forging, the use of a billet with such a small relative thickness not only limits the range of applicable geometric parameters but also causes buckling. The authors propose to solve this problem by using an additional tool that has an active effect on the inner surface of the workpiece, and thus makes it possible to control the forging process conditions. The tool is a plastic insert, i.e., an additional flexible core made of a low-melting alloy. Theoretical and experimental results presented in this paper provide a considerable insight into the cold forging process for thin-walled hollow balls. The effects of the plastic insert geometry and dimensions on the forging process are also examined. A solution is proposed to ensure that the forged part meets all requirements.