Study On The Aging Forming Law Of 7075 Aluminum Alloy Variable Cut Panel

In recent decades,with the rapid improvement of manufacturing technology in the field of aerospace and aviation,the traditional riveting structure is not fully satisfied with its production demand in the process of aircraft production,which is replaced by a higher performance,more lightweight aluminum alloy panel structure.Because of its special plate structure and lightweight characteristics,the integral panel is widely applied in the field of aviation and defense.The structure of the whole wall is complicated,and it is difficult to control the forming of the traditional forming process.As a new processing technology,the creep aging forming technology has a unique advantage in controlling the sheet forming.As a typical structure of the whole wall panel,the research on the aging forming of the variable section panel is less.Therefore,it is necessary to study and summarize the law of the aging forming of the variable cut panel,and provide the theoretical basis and guidance for the actual production.In this paper,7075-T651 aluminum alloy variable cut panel is taken as the research object.The process test and finite element simulation method are used to study the aging forming law of the variable cut panel respectively.First,through the orthogonal experiment and mathematical analysis,the effect of four main factors,aging temperature,aging time,section width ratio and width of cross section width,on the law of springback is discussed.The results show that the effect of process parameters on springback is aging time > width >width and thickness ratio >aging temperature,that is,aging time has the greatest impact on springback,followed by plate width,width and thickness ratio,aging time has the smallest effect on rebound rate;in addition,the inconsistency of rebound rate after aging treatment with different thickness of cross section panels is found.Secondly,the uniaxial tensile test of 7075-T651 aluminum alloy standard specimen is carried out,and the creep strain data of different tensile stress and time are obtained.The creep constitutive equation is derived from the obtained experimental data,and the accuracy of the constitutive equation is verified by comparing the calculated data fitting curve with the experimental data curve.Finally,based on the above experimental results and the derivation of the constitutive equation,the ABAQUS finite element software platform is used to establish the creep aging model of the 7075 aluminum alloy variable section plate,and the aging process of the 7075 aluminum alloy variable section plate is further studied.The results show that: the stress,creep strain and the location of the specimen in the mold will be changed at different stages of aging.The parameters such as the radius of the die,the width of the plate,the ratio of the width of the section and the loading pressure have an effect on the rebound of the plate after the aging process,and the law is in agreement with the conclusion obtained from the experiment.