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

采用直径为4.0、7.5和40 mm的半球形凸模，对厚度为0.2和0.02 mm的铝箔和铜箔，以及厚度为0.035 mm的铜箔进行了成形性研究。此外，使用厚度为1.0mm的铝板和厚度为0.6mm的磷脱氧铜片。在聚四氟乙烯（PTFE，标称厚度为0.05mm）上滴上机油，用石墨脂和机油作为坯料和冲头之间的润滑剂。结果表明：厚度的增加提高了临界成形深度.这已经被报道了。在本工作中，对于厚度为0.2 ~ 0.02mm的情况，也得到了同样的结果。提出了一种有效的等厚效应方法--叠层法。在这种情况下，层压的片材是相同厚度或不同厚度或不同材料的片材。临界成形深度也通过层压两个或更多个片材而改善。该方法可使临界成形深度得到较大提高。结果表明，板料厚度应变分布对临界成形深度影响很大，要提高临界成形深度，必须使板料厚度应变均匀分布在板料与凸模接触区域。

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.