Analysis of a New Process for Forming Two Flanges Simultaneously in a Hollow Part by Extrusion with Two Moving Dies

This paper presents a new method for forming flanges in hollow parts. The process consists of an extrusion with two dies that move in an opposite direction to that of the punches. This particular kinematics of the tools makes it possible to form two flanges simultaneously in a single tool pass. The proposed method was investigated using a tube made of steel 42CrMo4. It was assumed that the extrusion would be conducted as a cold forming process at ambient temperature. Different diameters and heights of the impression made in the top and bottom dies were used. It was demonstrated that the main failure mode of the proposed technique was an unintended increase in the inside the diameter of the workpiece in the flange zone. The results showed that the above parameters had a key impact on the achievable maximum flange diameters and heights.