Investigation on precision warm hydroforming with independent circumferential pressure of high-performance aluminum alloy parts with special-shaped bottom

Abstract

High-performance aluminum alloy is light, has high strength, but is very difficult to be formed. In the forming process of aluminum alloy parts with special-shaped bottom, there are defects such as poor fittability accuracy, instability, and cracking at the complex bottom, and the forming accuracy is an important performance index to characterize the forming quality. In this paper, a precision warm hydroforming scheme of pre-bulging and deep drawing is designed, and a method of applying independent circumferential pressure on the periphery of the flange in the later stage of pre-bulging is proposed to maintain the shape of the bottom and improve the fittability accuracy. The effects of temperature difference and independent circumferential pressure on the wall thickness and fittability of the part are studied. At the same time, response surface method is used to study the interaction among pre-bulging pressure, liquid chamber pressure, and circumferential pressure, and the optimal forming conditions are obtained after optimization and compared with the test piece. The results show that independent circumferential pressure can significantly improve the ability of the bottom of the pre-bulged part to maintain the acquired shape, and the temperature difference can effectively improve the plasticity of the sheet, the depth of drawing, and the quality of the part. After optimization by response surface method, the minimum wall thickness of the part is 0.8013 mm and the fittability is 94.2%. The forming quality parameters of the test piece are in good agreement with the numerical simulation parts, which indicates that this simulation can effectively predict forming situation of the part, and provides scientific guidance for precision forming of complex-shaped bottom parts.