Hydroforming of typical hollow components

Five hollow components with complex cross-sections, including two automotive parts, were formed successfully in a hydroforming press with a maximum pressure of 400 MPa, under computer control. The thickness distributions are discussed in detail for every component, in particular for a chassis part. The materials of these five components cover aluminium alloy, stainless steel and mild steel and the application fields involve the aircraft, aerospace and automotive industries. Among these components, the maximum diameter of one hydroformed part is 161 mm and the maximum thickness is 4 mm. For parts with a greater expansion ratio, more than 50%, or low formability materials such as aluminium alloy, wrinkled tubular blanks can be used as preforms to form hollow components. By using this method, material is first accumulated in the expanding area by the formation of wrinkles, and then the wrinkles are flattened to shape the part by increasing the internal pressure in the calibration stage. The important thing point is to obtain “useful” wrinkles instead of “dead” wrinkles.