An Experimental Study Of Drawing Of Wrought Magnesium Alloy Sheets

Magnesium alloys possess many advantages with low density, high specific strength andspecific stiffness, strong capacity of anti vibration and damp, excellent electromagneticshielding, easy recovery and so on, which is bright promising to be widely used as largearea covering in electronic, car, vehicle, aviation and spaceflight field and so on, and isregarded as 21st century's metal materials with the best developing prospect.It has important realistic meaning and economic worth to study the forming law and thethermal forming technology of magnesium alloy sheets out of shape for realizing thepractical and industrialization of magnesium alloy sheet processing.Wrought magnesium alloys have better strength and plasticity, smaller grain and loweringredient segregation than casting magnesium alloys, which is excellent performancemagnesium alloys. However, the magnesium is close-packed hexagonal structure, so itsplasticity deformability and rate of finished products are low. When heating certaintemperature, the sheets work hardening process is constantly offset by the process of thereversion an recrystallization in the state of thermal plasticity. In this way, the magnesiumalloy sheets are in a kind of state of softening of low intensity and high plasticity, and theforming can obtain obvious improvement. It is one of major research objects aboutdeveloping wrought magnesium alloys to study the technology of magnesium alloys sheetpressing, improve its deformability and expand its application fields.The major direction of this article is drawing which used widely in pressing technology.AZ31was the material used in the experiment, whose application is the most and theperformance is excellence. The influence of some processing parameters in blank drawingto the drawability of the blank was researched through the drawing experiment ofcylindrical specimens. The mould for drawing was designed whose punch and die were alldivided, and the blank-holding block was movable. That was convenient for the furtherstudy.A furnace was used. The temperature can be exactly controlled and the blank will not beoxidized. Heating rods were put into the mould to heat them. AC contactor and digitaltemperature controller were used to set and maintain the temperature.The blank holding force was a key parameter in drawing. Three ways of blank holding wereapplied in this paper, and the one used spring was best. It was improved later. Two ways to estimate the blank holding force were verified separately, which provides some referencefor the drawing technique.The temperature was an important parameter. The deforming features of magnesium alloyunder thermal state were generalized by the experiment. The feature and reason of somemain drawbacks were analyzed. The increment of the slip system under thermal state wasthe main reason for the improvement of the plastic. A suitable range of the formingtemperature is 180℃～240℃.The mould structure parameters can deeply impact the forming of the blank. The radii ofthe punch and the die were 5mm and 10mm separately in two experiments. The results werecompared to choose the proper value. The proper range of the space between punch and diewere.The forming speed was vital in the experiment. So the hydraulic press and a slower speedwere chosen to assurance the integrity of the specimens.The fraction and lubrication were introduced and two proper lubrications were used. Theparts on the mould to lubricate were analyzed.