Study on hydroforming of AA6061-T6 aluminum alloy sheet based on upper sheet

Forming large thin-walled hemispherical parts by hydroforming, serious thinning of wall thickness, instability of suspension area, and fracture are often accompanied. In order to solve the above problems, this paper takes AA6061-T6 aluminum alloy thin-walled hemispherical parts as the research object, and uses the method of finite element numerical simulation analysis and experimental verification to carry out the formability analysis of double-layer sheet hydroforming. In order to improve the accuracy of numerical simulation, uniaxial tensile tests are carried out on AA6061-T6 tensile specimens. Based on the BP neural network prediction model, a constitutive model that can truly reflect the plastic deformation characteristics of materials is established, which can provide more accurate material properties for numerical simulation. In this paper, the wall thickness and fittability of the parts are taken as the evaluation indexes, and the simulation analysis of the double-layer sheet hydroforming is carried out combined with the pre-bulging process, and the process flow of the single-sheet and the double-layer sheet hydroforming is compared and analyzed. The forming law of formed sheet under different friction coefficient between sheets and different upper sheet thickness is discussed. In addition, the influence of different temperature on the forming quality of parts is also discussed. It is found that the sheet metal will soften at the appropriate temperature, and the wall thickness distribution of the parts suspending area will be further improved.