| Making lightweight components from AZ31B magnesium alloys is an important way to achieve energy saving and emission reduction.However,the main problem of AZ31B magnesium alloy forming at present is its poor formability at room temperature.In order to better solve the forming problem of AZ31B magnesium alloy,a new technology was explored in this paper,which was named oil-immersed hydraulic warm forming technology of magnesium alloy sheet.The principle of this technology is that the die containing AZ31B magnesium alloy sheet was first immersed in the heat conduction oil and then heated rapidly to make the AZ31B magnesium alloy sheet hydroforming at a suitable and uniform temperature and finally the forming parts were obtained.The application of this technology can not only improve the properties of AZ31B magnesium alloy sheet after forming,but also enrich the forming mode of magnesium alloy.The main contents and results are as follows:(1)The tensile strength of AZ31B magnesium alloy at different temperatures was obtained by tensile test at high temperature.According to the theoretical analysis and empirical formula of relative scholars,the upper corner radius of forming die was calculated to be 10 mm,the radius of the lower corner is 6mm.At the same time,the values of the drawing force and the blank holder force at different forming temperatures was obtained.(2)A set of experimental equipment for oil-immersed hydraulic warm forming of magnesium alloy sheet was developed.The experimental device includes a heating and temperature compensation system,a hydraulic system,a hot oil circulation system,and a cooling circulation system.The device is very accurate in forming temperature control.(3)The experimental results show that the optimal process window of oil-immersed hydraulic warm forming for AZ31B magnesium alloy sheet with a thickness of 1mm is:the forming temperature was 200?,the torque is 230N·m,the hydraulic pressure is 2MPa,and the lubricant is needed for forming.(4)The wall thickness distribution of AZ31B magnesium alloy sheet after warm forming was studied.The results show that the wall thickness is gradually reduced from the flange of the forming part to the bottom of the forming part.The maximum thinning rate of the molded parts without lubricant is up to 67%,but the maximum thinning rate of the molded parts using the lubricant is reduced to 49%.The use of a lubricant can significantly reduce the extent to which the wall thickness of the formed part is reduced. |
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