Experimental and numerical study on shearing of a rod to produce long billets for cold forging

Abstract

In this paper, we consider the process of shearing a rod to manufacture relatively long billets (compared to the rod diameter) in automatic multistage cold forging. We studied this experimentally to determine the macroscopic characteristics of the billets. Based on this information about the shearing phenomena, we present a finite element analysis model with emphasis on the boundary conditions on the rear side. We also present an engineering approach to the separation of the material into two parts based on an element degradation scheme with a modified Freudenthal damage model. We applied the theoretical model to an actual industrial machine, and comparison between the experiments and predictions showed that they are in excellent agreement. We discovered that the varying force exerted on the material, due to the impact of the shearing stroke, is important; we addressed this using two input shearing constants reflecting the backward motion of the rear that occurs as a reaction.