A study on cold forging process sequence design of terminal pins for high-voltage capacitors

Abstract

A terminal pin, which is a component of high-voltage capacitors, has a plate-shaped head section with a thickness of 0.8 mm. The current manufacturing process, in which the head section is welded on the body section, has yielded substantial deviations in part qualities such as dimensional accuracy, mechanical strength and electrical stability. In this paper, a cold forging process sequence was proposed in order to produce the terminal pin as one piece. The plate-shaped head section requires an upsetting in the lateral direction of a cylindrical billet, which is followed by a blanking process. However, with only designer's intuition, it is difficult to predict precisely the deformed geometry obtained by the lateral upsetting process since metal flows along axial and lateral directions would occur simultaneously. Therefore, in this study, three dimensional finite element analyses were applied to the lateral upsetting process in order to determine the proper geometry of the initial billet. Once the geometry of the initial billet was determined, intermediate forging sequences were designed by applying the design guidelines of cold forging. Based on the proposed process sequence, a die set was manufactured and cold forging experiments were conducted.