摘要 :
The demand of various industries ofmicro-miniature modern technology to find new solutionmethods in a highly efficient mass production for a variety of micro-part is increasing.Hydroforming has a great potential to be used in mass...
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The demand of various industries ofmicro-miniature modern technology to find new solutionmethods in a highly efficient mass production for a variety of micro-part is increasing.Hydroforming has a great potential to be used in mass production.Problems that occur in the field ofthe process production of micro sheet is when the sizes of materials is reduced at sub millimeter range,grain size have a major effect on material properties,plastic deformation,and the overall process the establishment,The size effect causes formability of micro sheet to be poor.To improve the formability ofmicro sheet,new methods are needed.In this project a new method is presented,namely the use of Teflon to help improve the fonnability of micro sheet.This paper discusses the basics of the sheet hydroforming system,detects the Teflon material properties,and explains the process of micro sheet hydroforming with Teflon material in improving the micro sheet formability.For the experiment,micro sheet hydroforming with single pressure is used.Teflon material is used in the formation process.
Free bulge test is done to investigate the size effect and influence of Teflon sheet on the formability of SS304micro-sheet metal.Research results reveal that:l)the flow stress increases with the thickness of the SS304micro sheets;2)the elongation of material sheet decreases with thickness weakening;3)the use of Teflon material can increase the crack pressure of the micro sheet.In other words,it shows that Teflon material has positive effect on micro sheet formability.Teflon can generate higher bulge levels and also reduce the thinning rate of the thickness compared to the conventional micro sheet hydroforming.
Subsequently,Finite Element Method was used to simulate the Teflon assisted bulging processes of the micro sheet.To validate the prediction obtained from the simulation.a number of micro sheet hydroforming experiments were conducted.
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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...
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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.
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