Springback,an undesirable shape change in component which occurs during unloading of component from die,becomes hard to arrest as die geometry becomes increasingly complex.In the present study,the variation of Springback with curved line of bend has been examined for two U-shaped parts using finite element numerical simulations.The two geometries which have been considered are:SRail Benchmark(Numisheet'96),and C-Tray(rectangular tray with circular edges).It was noticed for both the geometries that Springback is relatively higher for free ends and straight sections of line of bend than the curved portions.Subsequently,to contain the Springback,higher and variable restraining(blankholder)forces were applied at areas where springback was relatively more,using split blankholders.It was observed from simulations that though variable higher restraining forces reduced the overall springback in some cases,the pattern of variation of springback along curved line of bend remained extremely similar to that with uniform blankholder forces.This indicates that the curvature of line of bend has a pronounced effect than variable blankholder forces in determining springback.The numerical analyses were performed using finite element stamping simulation software,PAM-STAMP 2G,for two materials,namely,Al-Li alloy and Standard Steel.
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