Optimal Process Control Parameters Estimation in Aluminium Extrusion for Given Product Characteristics

This paper investigates a technique to find an optimal set of conditions for an isothermal process to extrude a product for a given shape and material properties with minimal defects. The inputs to this model are: the product geometry and its material data such as flow curve and microstructure during dynamic recrystallization. This is an inverse problem and the model is formulated as a non-linear leastsquares minimization problem coupled with a finite element model for the extrusion process. It is done by constructing an iterative procedure using an optimisation routine such as MATLAB’s lsqnonlin and at each iteration, the extrusion flow is solved using ABAQUS. First all control points of a Bezier-curve for the die surface that minimizes the redundant strain inside the deformation zone are found. Then the initial billet temperature, die temperature and the ram speed that closely match with the strain rates and temperatures for the desired microstructure (grain size) are obtained.