Study on Forming Limit of Irregular Axial Holes Formed by Open-Die Cold Extrusion

Abstract

The parts with axial special-hole, which are difficult to be processed by traditional machining process because of the high cost and low efficiency, are widely used in many fields. In this paper, a new practicable method to form axial special-hole by open-die cold extrusion is put forward. The four failure types of forming axial irregular-holes by open-die extrusion are analyzed. The key parameters, cone angle, reduction, original ratio of the thickness-diameter, etc., which largely influence forming process and the limits range is analyzed by numerical simulation , and make an experiment to verify the results. Based on the analysis, the law of shaping and the limit of the key parameters are concluded. The optimum range of the die’s cone angles is from 16° to 22°.The largest reduction is 24% for the billets with concave outer profile and 22% for the billets with convex outer profile.