Research On The Drawing Process And Spring Back Control Of The B-pillar Reinforced Panel

High strength steel with small thickness is leading the trend of developmentof automotive technology, for it is well coincide with requirement of energysaving, environmental protection and crash safety. However, it is more inclined tocrack, wrinkling and spring back in the stamping process compared withlow-carbon steel. To put the forming process into practice, some key technicalissues are studied.Taking B-pillar reinforced panel as research object, finite element codesDYNAFORM and AUTOFORM were used to analyze the stamping process andcontrol the defects. Firstly, two schemes were designed according to the structurefeatures of the part, and that the flange was designed in punch part is the firstscheme, while the flange was designed in binder as the other one. The first optioncan get a better forming quality according to the simulation results. Secondly, dielayout of close, half-open and open draw bead was assigned separately to thecorner and middle binder of drawing part, and the result shows that the half-opendraw bead is better to others in control local defects. Thirdly, base on thedifference of formability behaviors among B340LA, DC04and DC06, aconclusion was drawn that the high strength plate is likely to crack, winkling, andlargely spring back. Finally, four main parameters of blank holder force,clearance between die and punch, friction coefficient and die radius wereoptimized via composite method of orthogonal experiment and gray correlationtheory, and the combination of the parameters was achieved to effectively controlwrinkling and crack defects.On the basis of the above-mentioned process optimization, further researchof spring back control was conducted by parameters control and spring backcompensation. The result indicates spring back compensation has a better controleffect than parameters control which may cause crack or wrinkling defects. Tocompensate the B-pillar reinforced panel, the function of spring backcompensation in DYNAFORM and globe smooth method in THINKDESIGNwere used, and spring back within reasonable limit was reached eventually.