摘要: Micro forming is a well-suited technology to manufacture tiny mechanical parts,particularly for mass production.Compared to other manufacturing technologies,micro forming features specific economic and ecological advantages.In the... 展开 Micro forming is a well-suited technology to manufacture tiny mechanical parts,particularly for mass production.Compared to other manufacturing technologies,micro forming features specific economic and ecological advantages.In the micro sheet hydroforming process,size effects play an important role in plastic deformation.Size effects are mainly concerned with the number of grains,size,and frictional behavior.At the micro-level,Parts composed of a limited number of grains,so material properties are highly dependent on orientation and tendencies of each grain,which not only effects the flow stress but also results in poor formability. PTFE(Teflon)is used in this study to improve the formability in the sheet hydroforming process,which helps to reduce friction,wear,and energy consumption of machinery.The research on micro-sheet hydroforming of SS304and copper sheets was performed.The mechanic''s information on micro-forming was reviewed;later on,a micro-sheet hydroforming test rig was designed.Additionally,the experiments on the micro-SS304sheet and copper sheet with and without the addition of PTFE at different thickness distribution,bulge heights,and cracking pressure were carried out.Finally,finite element analysis(FEA)was performed by analyzing crucial parameters such as sheet thickness,profile shape,and dome height of the micro-sheet.The application of PTFE material in the interface of micro-sheet and die can significantly increase the cracking pressure,the bulge height,while reducing wall thickness.The results showed that the application of the PTFE materials in the bulging test could significantly increase the pressure of the explosion.The addition of PTFE material Indicates that materials had a positive effect on the formability of micro-sheets.Furthermore,PTFE helps to enhance the deformation effect when the thickness of the micro sheet decreases,also the PTFE(Teflon)material helps to generate a high level of bulges hence producing an increase in the thinning range of wall thickness as compared to the conventional micro sheet hydroforming besides,resulting in thinner walls.Further study of the methods to improve the micro-formability(FEA)method with different coefficient of friction was studied.The results indicated that the utilization of Teflon could reduce the friction coefficient from0.15-0.01.The experimental and numerical study was successful in developing new methods to improve the formability of micro-sheet hydroforming and the advantages of Teflon in improving the formability of micro-sheet.The FEA analysis result has good agreement with experimental findings. 收起