Optimization of hydroforming process for deep drawing of AA7075 using finite element simulation and response surface methodology

Abstract

Aluminum 7075 is a functional aerospace alloy that has high strength and low formability during room temperature deep drawing. Therefore, to avoid warm forming process and relative difficulties, careful control in the process design is needed to enhance quality of drawn part and improve die life. In the present work, an attempt was made to experimentally and numerically study effect of hydrodynamic deep drawing process such as die geometry and fluid pressure on thinning ratio and punch force. Statistical analysis based on response surface methodology was carried out to correlate empirical relationship between die corner radius, punch corner radius and die fluid pressure as process factors and maximum thinning ratio and punch force as responses. Sensitivity analysis was also performed to find which factor has great impact on aforementioned responses. Further, optimization was carried out by use of desirability approach to find optimal parameter setting to attain minimum thinning and forming force simultaneously. Results indicated that punch and die corner radius followed by fluid have significant effect on the process quality characteristics. Moreover, setting of 9.3mm punch corner radius, 2mm die corner radius and 26MPa fluid pressure causes desirability 71% incorporating 31% thinning and 175MPa punch force. The obtained optimal results were then verified through both FE simulation and confirmatory experiment.