Effects of pre-bulging on 2024 aluminum alloy complex-shaped components

To improve the poor plasticity of 2024 aluminum alloy sheet, which causes wrinkle and fracture in conventional deep drawing of complexshaped components, hydromechanical deep drawing (HDD) with pre-bulging was investigated. The loading paths of chamber pressure and pre-bulging pressure were designed and optimized by numerical simulations and experiments, and effects of loading paths were obtained and analyzed for thickness, stress and defects. A reasonable loading path was determined. Thickness is more uniform when pre-bulging pressure is 2 MPa and chamber pressure is 15 MPa. The suspending area of a blank wrinkles easily between the punch and the die when pre-bulging pressure is smaller than 1.5 MPa; fracture occurs for the suspending area of blank between the punch and the die when pre-bulging pressure is larger than 8 MPa. The results show that a helpful friction can be generated, the stress state can be improved, and fracture and wrinkle can be avoided by a reasonable pre-bulging in the suspending area of the blank for a complex-shaped component. The uniformity of thickness and forming limit can be enhanced.