The Age Hardening Effect On The Forming Performance Of 6021-T4 Aluminum And Robust Stamping Process Design

As the situation of energy, environmental protection and other aspects is becoming more and more serious,forcing cars must reduce their weight to achieve the goal of energy conservation and emissions reduction. In order to meet the development requirements of automotive light-weighting,more and more lightweight materials are applied to car. Many automobile factory choose Aluminum alloy to replace the steel plate to reduce vehicle weight,because of its small density,corrosion resistance,bake hardening characteristics. Due to the differences between aluminum alloy and steel plate,aluminum alloy and steel plate are different in mechanical properties. So we can’t apply the traditional steel plate stamping forming numerical simulation theory and design experience of traditional steel plate stamping process to design the stamping process of aluminum auto body parts. Because the aluminum plate exist age hardening phenomenon,the material parameters of aluminum alloy will change with the storage time, and it lead to the quality of after stamping parts is unstable. Therefore,to solve the problems occur in the process of aluminum alloy applied in car body for auto light-weighting is of great significance.This paper comprehensively introduces the research status of aluminum alloy for car body, and systematically introduces the principle and finite element theory of numerical simulation of sheet metal stamping,mainly analysis the key techniques of numerical simulation of aluminum sheet stamping forming. On the basis of predecessors’ experience and research results,the author summed up a set of suitable numerical simulation theory for alumi num panel stamping.Due to the aluminum plate existing age hardening phenomenon, the material parameters are changed with the increase of storage time. In order to study the effect of age hardening on the aluminum sheet forming performance,this article respectively to deposit 0 month,3 months and 6 months of the 6021-T4 aluminum plate for cup drawing test and tensile test. The author analyze the 6021-T4 aluminum material parameters change trend caused by age hardening phenomenon,and it’s effect on the performance of stamping formability. The analysis of the experimental results show that the age hardening will make aluminum sheet stamping performance becomes poor.Because the aluminum alloy for auto body and steel are different on mechanical properties,the stamping process design of the aluminum plate and steel plate must also exist differences. In this paper,according to the characteristics of the aluminum alloy plate and combined with engineering practice experience,the author designed the stamping process of one structural part of Shanghai GM car body, and analyzed the difference between aluminum and steel sheet on stamping process design.The age hardening phenomenon of aluminum alloy cause its material parameters change,that lead to the stamping process of aluminum alloy is not stable and qualified rate of auto body parts is low. In this paper, after design the stamping process of the structural part of car body, the author continue to optimize the stamping process and make it robust.After Introduce the concept and basic theory of robust design, elaborate the taguchi method,and determine the robust design steps based on taguchi method,the author use taguchi methods to optimize the process parameters of car body stamping process. Without any increase in the mold design and manufacturing cost,this method improves the robustness of the stamping process of the aluminum car body part and provides guidance for the mold debugging. This paper has some engineering practical value.