Research on the forming of automobile fender by hydro-mechanical deep drawing based on numerical simulation

Aimed at the problem of crack and deforming deficiency in forming the automobile fender with complex surface structure and shallow drawing, the numerical simulations of hydro-mechanical deep drawing were carried out by employing the large non-linear dynamic explicit analytical software ETA/Dynaform5.5. The die surface was optimized design, and comparatively analyzed the forming laws of the fender in the common drawing and hydro-mechanical deep drawing. The influence of two processes on fender forming quality was investigated and analyzed by taking the thickness distribution and forming limit diagrams (FLD) as standard. Under the reasonable chamber pressure loading path, the results show that the hydro-mechanical deep drawing can more effectively control crack and deforming deficiency, relative to common drawing. The die fittingness and flow uniformity can be increased. The optimum chamber pressure loading path of fender's hydro-mechanical deep drawing is as follows: at the initial stage, the chamber pressure is 0; at the middle stage which the panel and the male punch mostly joint together, apply 2 MPa chamber pressure on the fender and maintain a period of time, and then increased to 5 MPa; in the end, rapidly increased to 25 MPa. The formed automobile panel obtained higher quality with uniform thickness distribution.