Optimization Of Process And Design Of Mold For The Inner Panel Of Car Trunk Lid On AutoForm

The inner panel of car trunk lid is a typical automobile panel, with a large overallsize, complex space shape and many holes etc. These features make the stampingprocess (drawing, piercing, flanging, restriking and trimming process etc.) complex.Fracture, wrinkle and other defects usually occur in forming process of the inner panelof car trunk lid, which bring great difficulty to processing. In order to shorten themold development cycle of the inner panel and to ensure the quality of stamping.Combined with practical engineering, the forming process of the part was simulatedby the software AutoForm in this paper. The forming defects were predicted andeliminated, the forming process was optimized, and the mold was designed andproduced. Eventually satisfactory parts were obtained.The main research contents and achievements of this paper are as follow:1) First, according to structure features of the inner panel, its forming processwas designed, which involved setting the stamping direction, determining the blankshape and size, and designing the binder, the drawbead and the addendum etc.2) The initial simulation of forming the inner panel was completed on AutoForm.Half of the part was simulated for the symmetrical shape. Processing parameters suchas blank dimension, die corner radius, punch corner radius, punch-die clearance, blankholding force and coefficient of friction were determined to be1700mm×1200mm,15mm,10mm,0.65mm,500KN and0.15in the initial simulation, respectively. Formsimulation results, fracture was found in three regions, wrinkle was found in oneregion.3) According to the defects in the initial simulation, three optimizations weredone to eliminate defects of the fracture and wrinkle: Blank shape was changed fromsquare to irregular shape; Blank size was reduced from1700mm×1200mm to1550mm×1120mm; Binder at fracture regions was elevated2mm to reduce drawingdepth; Binder shape at wrinkle region was changed to insure length of the bindersection line less than that of the corresponding position of the part; Die corner radiusat addendum was increased from15mm to18mm, and the addendum punch cornerradius was increased from10mm to15mm; Die corner radii at cracking regions wereincreased respectively from14mm and3mm to18mm and4.5mm. Drawbeadresistance coefficient at fracture regions was reduced from0.35to0.3; Drawbead resistance coefficient at wrinkle regions was increased from0.1to0.2; Blank holderforce was reduced from500KN to450KN. The defects were almost eliminatedeventually. Processing parameters such as blank size, die corner radius, punch cornerradius, punch-die clearance, blank holder force and coefficient of friction wereeventually determined to be1550mm×1120mm,18mm,15mm,0.65mm,450KN and0.15, respectively.4) The forming mold was designed and produced based on the numericalsimulation results and the process after optimization. The quality of stamping part wasgood, and the forming process was verified to be feasible and reasonable.