Minimization of the Sheet Thinning in Hydraulic Deep Drawing Process Using Response Surface Methodology and Finite Element Method

In most of the sheet forming processes, production of the parts with minimum thickness variation and low required force is important. In this research, minimization of the sheet thinning and forming force in the hydraulic deep drawing process has been studied. Firstly, the process is simulated using the finite element method (FEM) and simulation model is verified using the experimental results. Then the sheet thinning ratio and punch force as objective functions have been modeled using the response surface methodology (RSM). In this model, process parameters such as punch nose radius, die corner radius and maximum fluid pressure are the variables. Required experiments for the RSM were designed using the central composite design method and performed by FEM. Finally, optimum point of the parameters has been obtained by minimization of the objective functions using the desirability function method. In addition to, optimum range of the parameters determined using overlying contour plots. Results show that the response surface models have a good adequacy. According to this model, increasing of punch nose radius and die corner radius, lead to decreasing of thinning ratio and increasing the maximum punch force. Also the maximum punch force increases by increasing the maximum fluid pressure. Optimization results represent reduction of the thinning ratio almost 10% compared with conventional results.