The preform design of forging processes plays a key role in improving product qualities, such as defect prevention, dimensional accuracy and mechanical strengths. In the industry, preforms are generally designed by the iterative trial-and-error approach, but it results in significant tooling cost and time. It is thus necessary to minimize lead-time and human intervention through an effective preform design method.
Since equi-potential lines between two conductors at different voltages are similar to the minimum work paths from the initial shape to the final shape, they can be used for the preform design, and then the optimization process is used to choose the equi-potential lines that will keep the die wear to a minimum. Because, in the forging process, the die wear is a function of various important factors, such as forming stress and strain, microstructure and mechanical properties of a product.
The objective of this study is to propose a new method for preform design in three-dimensional hot forging processes. The optimal preform design procedure using the equi-potential method consists of the following four stages: i) To locate the mass center of the final shape so as to coincide with that of the proportionally enlarged initial shape, ii) To calculate the equi-potential lines using the Finite Element Method, iii) To determine the range in which the die cavity is filled in full, and iv) To propose an optimal potential value of the electric field which gives an optimal die wear condition. In order to show the validity and effectiveness of the proposed method, a three-dimensional problem has been tested. In comparison with the results of the finite element analysis, it has been shown that the proposed method can be effectively and practically applied to the preform design of hot forging processes.
