Optimum preform design in close die hot forging

ABSTRACT

In conventional hot forging process of complex parts, about 20-40% of material is wasted as flash. Several research groups have investigated the design of preform die. The idea is based on a simple primitive geometrical shape that provides complete and flawless die filling with not more than 20% of waste. In this paper, a geometrical based method for preform design is presented. The proposed method is based on the idea of constant volume in the plasticity. Considering this idea, a python script was implemented in ABAQUS package which can design the preform based on the shape of the final part. The advantage of this implementation in ABAQUS is that the finite element capabilities of the ABAQUS can be used for simulating the forging process. To check the efficiency of the proposed method, an industrial part called "electric tension rod" was used. First, the optimum preform was designed based on the proposed method. Then, several finite element simulations were performed to find out the optimum geometry instead of the simple cylindrical rods which is normally used in industry. To validate the numerical results, the same preform geometries were machined and used in closed die hot forging. The experimental results show that by using this method, a reduction of 35% in flash material can be achieved which is in good agreement with numerical results.

Keywords

Optimization, Preform design, Close die hot forging