Multi-goal optimization of industrial extrusion dies by means of meta-models

In the design of complex extrusion dies, a number of different and potentially conflicting goals are involved in the process optimization such as profile tolerances, mechanical properties, aesthetical surfaces, and die life. Thus, a robust and comprehensive approach to investigate the problem is required that must be also compatible with the industrial timing. In this context, the aim of the present work was to perform a multi-objective optimization of industrial porthole dies for the maximization of the profile quality, expressed in terms of seam weld strength, of the production rate, that means balanced exit flow and maximized velocity, and of the die strength by means of meta-models. Two aluminum profiles were investigated. First, a thick round tube manufactured by means of a porthole die with three legs was selected as a starting case to define, fix, and validate the procedure. The gain achieved by the optimal design was compared with the experimental evidences of an already optimized configuration showing an additional increase in terms of welding strength and flow balance. In the second step of the work, the virtual optimization performed by means of meta-models was applied to solve a more complex industrial case of a hollow rectangular profile with four eyelets. For this, most significant improvements were attained not only for the seam weld quality but also for the die strength if compared to the performances of a starting configuration.