Research On Cold Stamping Process And Performance Of Magnesium Alloy Sheets

Magnesium alloys have low density, high specific strength, excellent shock absorptionproperties, electromagnetic shielding and radiation resistance, etc. Based on theseadvantages of magnesium alloys, mobile phone protection shells are made through the wayof cold stamping process. This will expand the application of magnesium alloys.With AZ31magnesium alloys as the object, sheets were prepared by the cross rollingprocess. Effect of the heat treatment on the organization and performance of magnesiumalloy sheets were researched. At the same time, a cold stamping die of mobile phoneprotection sheets were designed for a type of mobile phones on the market. Cold stampingformability of AZ31magnesium alloys sheets were studied by analyzing and comparingthe cold stamping process experiment with numerical simulation analysis results. Thefollowing conclusions are obtained.The AZ31magnesium alloys sheets were obtained by cross rolling the extrusive sheet.The rolling deformation was controlled every time at about15%. It was heated to360~400℃and incubated for0.5~2h between every two times, so the magnesium alloy sheetof0.8mm can be obtained by rolling.The effects of heat treatment on the microstructure and properties of magnesium alloyssheets were studied by metallographic analysis and tension test. After annealing, staticrecrystallization occured in the microstructure and the grains size were refined. Theminimum size of grains was14μm at200℃for120min. The tensile strength decreasesthan that of magnesium alloys sheets after annealing, while elongation increased obviously.The maximum tensile strength of216MPa was obtained at250℃×40min, and themaximum elongation of22.65%was obtained At250℃×60min.The stamping die was designed by CAD soft software. The influence rule of stampingprocess parameters on the stamping formability of magnesium alloys was studied by CAEnumerical analysis software. The optimal process parameters were determined. When theexperiment was conducted with the blank radius of20mm and the blank-holder force of 2000N and the friction coefficient of0.1, the stamping performance of AZ31magnesiumalloys sheets was stable.The deep drawing technology experiment of AZ31magnesium alloys sheets wasconducted. After comparing and analyzing the numerical simulation with experimentalstudy, the results showed that the mobile phone protection was successfully produced withmagnesium alloys sheet after cross rolling and heat treatment by cold stamping. Theprocess parameter includes blank thickness of0.75~0.65mm, blank-holder force of1400~2200N, blank radius of20mm, and lubrication of oil+graphite oil.