Formability in Biaxial Stretch of Aluminum Sheets and Foil with Very Small Punch

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The formability of Aluminum foil and Copper foil was investigated using semi-spherical punch which diameter were 4.0,7.5 and 40mm.The materials used are Aluminum sheet and foil Which are 0.2 and 0.02mm in thickness, and Copper foil which is 0.035mm in thickness. Moreover, Aluminum sheet which is 1.0mm in thickness and Phosphorus deoxidized copper sheet which is 0.6mm in thickness were used. All these materials were annealed.The PTFE (Polytetrafluoroethylene sheet, nominal thickness is 0.05mm) on which machine oil was dropped, Graphite grease and Machine oil Were used as the lubricants between blank and punch. The conclusions obtained are as follows.Increasing in thickness is improved the critical forming depth. This has already been reported. In this work, same consequence for 0.2 to 0.02mm in thickness were a also obtained. As a useful method to give same thickness effect, laminating method was proposed. In this case, the sheets laminated were same thicknesses or different ones or different material ones. The critical forming depth is also improved by laminating the two or more sheets. The critical forming depth is improved fairly by this method. It is noticed that the critical forming depth is largely affected in the thickness strain distribution.It is important to improve the critical forming depth that the thickness strain is distributed uniformly over the contact region between blank and punch.