Micro Cup Drawing without Wrinkles Using a Bulged Punch

A novel Bulged Punch (BP) was successfully performed for wrinkle elimination in micro cup drawings of AA1235 foils. BP was used to create a specific enlarged gradual punch profile before wrinkles began to occur until the end of the stroke, with fully annealing of AA1235 occurring before accumulative roll bonding (ARB), asymmetric rolling (AR), and stress relieving of a rolled blank, and deep drawing. The research purpose is to create a micro cup without wrinkles. The method was studied via experimentally deep drawing a blank thickness of 300 m with pairs of dies-BPs supported by a press tool. Blanks were processed under (a) ARB 4 and 6 cycles, (b) combined ARB with AR and (c) post-heat-treatment. The process was selected when a force (F) from the simulation matched with the measured value. The results showed that BP can simultaneously eliminate the occurrence of wrinkles at the cup edge, reduce the earing occurrence, increase cup corner thickness, and decrease the edge thickness. Simulation models were built using the finite element method software LS Dyna, which supports experimental evidence. The findings imply that BP can successfully eliminate wrinkles at the cup edge.