Study on gas forming technology for complex curvature aluminum alloy thin-walled components
With the progress and development of science and technology,the demand for industrial alloy integral thin-wall components with light weight,high strength,large size and complex shape is increasing,and the manufacturing process also has higher requirements.Because of its good plasticity and relatively low price,aluminum alloy has become an ideal material for the manufacture of parts for carrying equipment.To meet the demands of rapid and high-quality forming for lightweight thin-wall components with complex curvature,5754 thin-walled aluminum alloy members with large depth-to-diameter ratio and complex curvature characteristics are taken as the research object in this study,which employs advanced gas forming technology to experimentally and numerically investigate the forming performance of 5754 aluminum alloy complex components.Firstly,a self-designed rapid gas forming platform for sheet metal is established to conduct gas forming experiments on thin-walled components made of 5754 aluminum alloy with complex curvature.The optimal values for cavity air pressure and blank edge holding force are determined through single-variable method.Secondly,a finite element model for the gas forming of aluminum alloy thin-walled components is established using LS-DYNA software.The forming process and quality of complex-curvature thin-walled aluminum alloy components under various process parameters are examined.Finally,combining numerical simulation with experimental result data,the forming depth,wall thickness distribution,and maximum stress and strain of the sample are used as forming performance characterization parameters,and a parameter analysis is conducted to study the effects and mechanisms of cavity air pressure and blank holding force on forming performance.The results show that,in the case studied,the minimum cavity pressure required for mold sticking is 1 MPa.When the cavity air pressure is less than 1 MPa,the maximum forming depth continuously increases.The maximum stress and strain are located at the center of the main feature,and the wall thickness distribution increases from the center of the aluminum sheet towards both sides along the major axis.However,when the air pressure exceeds 1 MPa,the maximum forming depth remains constant.The maximum stress and strain are located on both sides of the center of the cavity,and the wall thickness distribution decreases first and then increases from the center of the plate to both sides along the long axis.Regarding edge holding force,when the blank holding force is less than 4.3 MPa,wrinkling defects occur on both sides of the flange and cavity.Increasing edge holding force effectively suppresses wrinkles,but it will increase the risk of local component rupture when it exceeds 4.9 MPa.Ultimately,through careful selection,the optimal forming air pressure and edge holding force are determined to be 1.2 MPa and 4.6 MPa,respectively.When the cavity pressure is 1.2 MPa,the component is fully formed and the forming quality is the best.Meanwhile,the holding force of 4.6 MPa effectively avoids defect formations such as wrinkling and cracking of the sheet. Therefore,the complex curvature aluminum alloy thin-wall components with good quality is formed by using the above optimum process parameters.
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