Research On Precision Cold Stamping Forming Of B-pillar Of Pickup Truck And Optimization Of Process-mold

B-pillar,as one of the important supporting structural parts in automobile,has complex structure and requires high strength and rigidity.Due to the poor plasticity of high-strength steel,B-pillar is usually manufactured by hot stamping,but hot stamping has the disadvantages,such as the high cost of production and long production cycle.This subject studies the precise forming process of B-pillar by cold stamping.Starting with the analysis of the problems that are easy to crack,wrinkle and springback in cold stamping,the cold stamping forming process scheme of B-pillar is put forward,and the process parameters and die surface are optimized to develop a qualified and economic cold stamping forming process of B-pillar.Firstly,based on summarizing the forming defects and control methods of high-strength steel,the formability of B-pillar is analyzed according to its geometrical characteristics,and the finite element models of drawing,flanging,trimming and springbacking of the part are established.The stress-strain tendency,material flow and thickness change of parts in each area during forming were studied by finite element results,then the forming defects of B-pillar were predicted.The wrinkling and cracking defects in B-pillar deep drawing are deeply analyzed,and the control strategies for optimizing the blank holder force,arrangement of deep drawing ribs,die clearance and die fillet are put forward.Secondly,in order to solve the problems of insufficient deep drawing and springback after trimming,the central composite test design is carried out with the influence factors of blank holder force,die clearance,1# and 2# of drawbar as the influencing factors,and the second-order response surface model of maximum springback and maximum thinning rate is established.The influence of single factor and cross factor on forming quality is analyzed,and multi-objective function is solved to obtain the optimum process parameters.Profile compensation control is adopted for springback after trimming,and corresponding drawing profiles and flanging profiles are obtained.Finally,the cold stamping forming process and die for B-pillar are designed jointly with the enterprise,and the die,punch,blank holder,positioning device and distribution of ejector bar are designed and optimized.Participating in the trial production of enterprises and proposing corresponding solutions,the qualified forming parts are obtained,and the cold stamping forming of high-strength steel B-pillar is realized.This paper has certain reference value to the actual production of similar parts for the results of defect control strategy and process parameter optimization model of high-strength steel B-pillar.