Research In The Forming Quality Control Of Aluminium Alloy Hood’s Outer Panel

Using aluminum alloy instead of steel for automobile body panel can greatly reduce vehicleweight. But the plastic formability and forming rule of aluminum alloy is different from the steel, soit need to study the process factors of controlling forming quality and unique forming rule which suitfor the panel of aluminum alloy. It has great practical significance to push the application ofaluminum alloy sheet in auto industry. Car body outer panels (such as engine hood outer panel) havemostly complex and irregular shapes. Compared with steel sheet, aluminum alloy sheet are moredifficult in forming the panels that will produce a great of quality problems such as seriousspringback, over thinning and so on. To seek the best forming plan, the conventional approaches liedon experiences or test-stamping either waste much time and cost or unable to deep research due tolimit of experiment conditions. CAE technique make not only it become able to predict formingquality of the panels, increase the efficiencies and decreasing the cost of die developing and stampingplan design, but also can study more deep and comprehensively on the interaction of various processfactors in forming the panels and work out better stamping forming plan on this basis.Based on Dynaform software platform, by analysing and comparing the forming rule and theforming quality during stamping the engine hood outer panels of A6111-T4P aluminum alloy and ofDQ steel, this thesis researched the effect of material parameters and process parameters on formingquality control of A6111-T4P. The Taguchi experiment scheme was used to do optimization processparameters design such as blank-holder force, gap between punch and die, drawbead depth and blankshape design of A6111-T4P outer panel. According to experiment, a solution was presented to controlthinning, shape precision and springback in forming the outer panel of A6111-T4P.The results shows that1. For the engine hood outer panel in the thesis, there not was any fractureand wrinkle in stamping effective region of A6111-T4P sheet and DQ sheet. The drawing thinningdistribution of A6111-T4P panel is similar to DQ, but the thinning is more evenly and the localmaximum thinning is lower than DQ. Two kind of material have similar die fittingness and can getgood shape precision under given process conditions. Whether before or after trimming, thespringback value of A6111-T4P panel is1.5to3.3times higher than DQ panel.2. Higher workhardening index can help A6111-T4P resist thinning in drawing; lower yield strength of A6111-T4Pbring good die fittingness. Smaller elastic modulus of A6111-T4P make it is difficult to control thespringback after trimming.3. Relative to the outer panel of DQ sheet, the key process parameterswhich affect the stamping quality (including drawing and springback) of A6111-T4P is clearancebetween punch and die and blank shape. In order to get high quality outer panel drawing part ofaluminum alloy (A6111-T4P), the best process parameters are as follows: blank-holder force is300KN, clearance between punch and die0.8mm, drawbead height14mm and rectangle blank.