Study On Forming Limit And Process Optimization Of Warming Stamping Of 6063 Aluminium Alloy

With the rapid development of automobile industry and the aggravation of energy crisis,higher and higher requirements are put forward for the lightweight target of automobile.Aluminum alloy plays an increasingly important role in automobile parts manufacturing due to its characteristics of high strength and light weight.However,the formability of aluminium alloy at normal temperature is poor,and the forming limit is low,and it is easy to break.The forming limit of aluminium alloy can be increased and the deformation resistance can be reduced by warm stamping process.Therefore,it is very important to study the forming limit of warm stamping process for aluminium alloy.In this paper,6063 Aluminium alloy is taken as the research object.Through the combination of theoretical calculation and finite element simulation,the following research work is mainly done:(1)The relationship between stress and strain of 6063 Aluminium alloy was studied by unidirectional tensile test.Based on the experimental data,the true stress-strain curves of 6063 Aluminium Alloy at 25 ℃,100 ℃,200 ℃ and 350 ℃ were drawn.The constitutive equation of 6063 Aluminium alloy is established by data processing.It is found that the yield stress and tensile strength of 6063 Aluminium alloy decrease obviously with the increase of temperature,the elongation increases with the increase of temperature,and the strain rate hardening index decreases with the increase of temperature.Temperature has a great influence on the properties of 6063 Aluminium alloy,while strain rate has a relatively small effect on 6063 Aluminium alloy.(2)Based on S-R theory and material performance parameters obtained from unidirectional tensile test,the forming limit diagram of 6063 aluminum alloy at 100 ℃ was calculated.The finite element model based on the bulging experiment of punch was numerically simulated.The forming limit diagram of 6063 Aluminium Alloy at 100 ℃ was also calculated by analyzing the post-processing files.By comparison,it is found that the difference on the right side of the forming limit diagram obtained by the two methods is small,and the difference on the left side of the forming limit diagram is relatively large.By means of numerical simulation,forming limit diagrams of 6063 Aluminium Alloy at 200℃,300℃ and 350℃ were obtained.(3)The forming limit diagrams of 6063 Aluminium alloy obtained at 100℃,200℃,300℃ and 350℃ are used as criteria.Through finite element simulation of warm stamping process of S-shaped rail of automobile,the influence of the stamping temperatures and blank holder loads of S-shaped railwas on formability is investigated.The results show that the optimum forming temperature for warm stamping of 6063 aluminum alloy of S-shaped rail is 300 C and the optimum blank holder load is 80 KN.