Multiobjective optimization problem of dieless incremental forming

Single Point Incremental Forming (SPIF) technology has been announced in the recent past to manufacture sheet metal products by using Computer Numerical Control machines (CNC). It has been frequently used in different fields like the aeronautics. In incremental forming, materials are submitted to permanent deformation by cold forming to produce a variety of three complicated dimensional shapes. The final form of the parts in sheet metal forming is highly affected by the spring-back and the pillow effect, occurring when the material is set free of the forming constraints. In this sense, the best solution is to adopt a process of multiobjective optimization in which a set of numerical simulations can be achieved on the basis of the box-Behnken experimental design. In this way, the design variables are wall angle, initial thickness, tool diameter and incremental size. To study the geometric characteristics, a cone-shaped part with circular base is considered. This paper aims to identify an overview of multiobjective design optimization of incremental metal forming parameters in order to minimize objective functions of pillow effect, springback and thinning rate simultaneously. In an attempt to solve fitness functions, the method of Multiobjective Genetic Algorithm (Moga) is developed in this investigation. In this case, we should consider several points of the appropriate process parameters which correspond to the best compromises with respect to several antagonistic objectives. As well as, a generation of the approximate Pareto optimal solutions is presented in this study. © 2015 Trans Tech Publications, Switzerland.