Research On Stamping Forming And Springback Control Of High-Strength Steel Automobile Structural Part

In recent years,with the increasing requirement for lightweight and collision safety in the automotive industry,high-strength steel is widely used in body structures with high cost performance,sufficient strength and rigidity,good energy absorption and fatigue resistance.However,high-strength steel is prone to cracking,wrinkling,insufficient forming and springback in stamping,which increases mold development and manufacturing costs.Therefore,how to effectively control the forming defects of high-strength steel parts has become the focus of the industry.In this paper,the rear seat mounted upper beam is chosen as the research object,and the key technologies such as process design,numerical simulation,multi-objective optimization and springback compensation are studied.The specific content includes the following three aspects:(1)The process analysis of the rear seat mounted upper beam is carried out,and from the perspective of ensuring the forming quality and improving the material utilization proportion,two kinds of drawing process plans are given:open drawing and closed drawing.The closed drawing is selected as the final process plan by Autoform rapid simulation comparison analysis.Based on the selected process plan,the detailed process design of each process was completed in NX according to the stamping process design specification.Then the finite element model of each process was established by Autoform,and the whole process numerical simulation of the parts was carried out.In the simulation process,the problem of cracking of the convex and flange during the drawing process and the cracking of the flange of the workpiece during the flanging and shaping process are mainly solved.(2)In order to solve the problems of insufficient drawing and large springback of rear seat mounted upper beam,Box-Behnken test with 4 factors and 3 levels was carried out to establish the response surface model,taking the safety area proportion and average springback as the optimization objective,the maximum thinning of product area as the constraint condition,and the blank holder force,friction coefficient,chamfer size and punch roundness as design variables.The variance test of the model shows that the established model can well reflect the responserelationship between the objective function and the constraint function to the design variables.Design-Expert software is used to solve the model to obtain the optimal process plan.The optimized scheme is used to simulate,and the errors between the predicted value and the simulated value are tested.The results show that the response errors of the three models are less than 2%,which verifies the effectiveness of the response surface optimization design.(3)On the basis of multi-objective optimization,in order to further control the springback,firstly,the springback size and distribution of each process are analyzed,and the appropriate compensation strategy is determined.Then,according to the compensation strategy,Autoform’s springback compensation function is used to control the springback of the final part within±0.8mm by one drawing surface compensation,one trimming surface compensation and one flanging and shaping compensation.Finally,the parts are subjected to the real-experimental test,and the parts are tested by hand,special inspection and 3D scanning,and the parts meet the requirements of forming and dimensional accuracy.