Research on hydroforming of 5A06 aluminum alloy semi-ellipsoid shell with differential thickness

Abstract

Abstract For the purpose of eliminating the annular welding seam of welding structures with a differential thickness, a hydroforming method with a flexible auxiliary plate was proposed to form an integrated semi-ellipsoid shell with a differential thickness. A 5A06 aluminum alloy plate with a radial differential thickness combined with a polyurethane plate was applied to form the integrated shell. The circular 5A06 aluminum alloy plate with a radial differential thickness was designed with a thin thickness in the middle and a thick thickness in the periphery. In the forming process of plates with a differential thickness, concentrated deformation and fracture may occur in the thin zone. According to the size of the target specimen, the testing plates were obtained by mechanical processing with two types of thickness ratios. Further, by means of deep drawing experiments, the thickness and strain of the drawn specimens were analyzed under different thickness ratios and hydraulic pressure. Compared to conventional deep drawing, the formability of 5A06 aluminum alloy plates with a differential thickness can be effectively improved by hydroforming. Under the hydraulic pressure of 10 MPa, the integrated semi-ellipsoid shells with the thickness ratios of 2/3 and 1/2 were obtained with the maximum thinning ratio of 8.5% and 10.9%, respectively. Meanwhile, the increased hydraulic pressure can effectively reduce the maximum thinning ratio of the thin zone, and further the superior uniformity of thickness distribution can be achieved.