Abstract: Preform design and optimization for bulk metal forming is a difficult issue in metal multi-forming process and also the key point for obtaining high quality product. Based on the core of evolutionary structural optimization(ESO) and considered the bulk metal forming features, a method-topology optimization method is proposed and adopted for preform design of bulk metal forming. The optimization techniques include optimization strategy, element removal and addition criteria, interpolation technology, etc are given in detail. A self-programmed code combined with the Deform2D software package for optimization system which objective is sufficient die filling and improved deformation uniformity, element removal and addition criteria is hydrostatic stress is developed. The preform optimization of an axisymmetric disk forging in open die forging condition is implemented and evaluated using the developed method. The result shows that the developed method is explicit in principle and simple to be carried out, has high operating efficiency and optimal accuracy, can run automatically once been integrated in program code. The satisfactory preform structure is obtained finally.

Key words: Evolutionary algorithms, Metal forming, Preforming, Topology optimization