Computer simulation of superplastic blow-forming in a conical closed-die considering uniform thinning

A mathematical model for analyzing the plastic deformation behavior of a sheet during a conical closed-die blow-forming is proposed. In the formulation of this mathematical model, uniform thinning in the free bulged region is considered. Using this model, the effects of various forming parameters, such as the die entry radius, friction coefficient, and inclined angle of the die, on the optimized pressurization profile, forming time and the thickness distribution of products can be discussed systematically. Furthermore, experiments using 8090 Al-Li sheets are carried out in conical closed-die superplastic blow-forming. The predicted thickness distributions of the SPFed product obtained with different friction coefficients along the die enty, sidewall and bottom are found to be closer to the experimental data than those obtained with a constant friction coefficient.