Research On Optimization Of Forming Parameters For Big Automotive Panel And Its Die Design

Rear floors are key part of the body structure, which play important role in supporting and shock absorption, and the operation of the rear floor has a decisive influence on the automotive safety and smooth ride. With the improvement of people's requirements on body interior space and safety, it need more large rear floor covering parts. Stamping die is most important tooling equipment during manufacturing rear floors, its design cycle, the cost and quality have closely effect on research and development as well as manufacturing cycle of body shaping. Meanwhile, the energy shortage problem makes it be very important to control the cost of the stamping die. At present, the main parameters design of the cover part mainly rely on repeated repair mode method to achieve improved quality of parts, which greatly increase the manufacturing cycle time and manufacturing costs of stamping die, and the traditional design of reinforcement distribution and the size of stamping die usually according to stamping die design handbook's empirical value, which may causes excessive structural rigidity and large weight of the die, increasing manufacturing costs. In order to shorten the large rear floor covering die manufacturing cycle and reduce manufacturing costs, this paper studied the a vehicle large rear floor cover. Finite element simulation software was used to analyze the drawing forming defects, such as crack, wrinkles and uneven thickness. The parameters of draw forming were designed and optimized, and got the qualified rear floors through trial production, finally, used decoupling ideas of the stamping simulation and structural topology optimization, optimized the original drawing punch structure and design new punch structure. Based on the above, this paper carried out the research as the following aspects:(1)Firstly, the structural characteristics of the rear floor were analyzed, and then the addendum design, the process design and the sheet size optimization were carried out.(2)The draw forming finite element model was established based on the factory empirical parameters. According to the simulated results of the rear floor, the forming limit diagram was analyzed. In order to solve the forming inequality, introducing draw bead to simulate forming quality, and made comparison simulated results between with draw bead and without draw bead ion analysis, such as forming limit diagram and thickness distribution.(3) Three objective functions were established, crack, wrinkles and uneven thickness, respectively. Adopting the height and fillet of draw bead, BHF and die entrance fillet as optimizing factors, a second-order response surface model with three objective values was obtained by fitting modelling analysis conducted by the combination of the software, such as matlab and design-expert. The accuracy of response surface model was verified, which was available for subsequent optimizations. Based on this condition, using multi-objective optimization technology according to genetic algorithm, the optimized target parameters of fracture, wrinkle and uneven were found. The optimal solution is that the height of draw bead is 6mm, the fillet of draw bead is 5mm, BHF is 150 t and die entrance fillet is 6mm. At last the optimize results obtained by simulation was verified by the finite element simulation, it turn out the crack was been avoided and uneven thickness improved significantly.(4)3D model of die was modified according to the optimize results, die manufacturing was completed. Subsequently, Trial production obtained qualified floor parts. Finally, the actual part's thickness were measured, which were compared with the simulation's thickness,it was been turn out that the match rate between actual thickness and simulation's thickness is 86.7%.`(5)Based on the numerical simulation results of rear floor, the forces analysis and mapping of punch were conducted. Then, opti-struct topology optimization was used to optimize the punch structure. Finally, on the basis of the optimization result, a new punch structure was designed. The new structure lose weight by about 20%, while ensuring that the deformation within the scope of the license. It indicated that the new punch is superior to the original punch.