Finite Element Numerical Simulation For Automobile Front Floor Forming

With the rapid development of economy,automobiles have become the main means of transportation in modern society.The demand of people for private cars is increasing,and the requirements for quality and appearance are getting higher and higher,which makes manufacturers have to speed up the development of new cars.Most of the parts of the car are stamping parts,so the stamping forming technology of the automobile panel has become a key factor restricting the development of the car.With the rapid development of finite element technology and computer technology,accurate metal sheet forming simulation technology provides driving force for engineering design.The use of simulation software can improve the reliability of the planning process and the design level of the die.In addition,press downtime and product rejection rate can be significantly reduced during actual production.The simulation results of the software are used to guide the actual production,which greatly reduces the design cost.In this paper,the front floor of a car is taken as the research object,and the numerical simulation analysis of the forming process is carried out by using the Autoform.The defects such as insufficient drawing,wrinkling and failure in the sheet forming process are predicted through simulation analysis.The simulation results were optimized by adjusting blank holder force,the drawbead parameters,the die clearance and the friction coefficient.At the same time,the influence of each influence parameter on the springback of the front floor was studied..The orthogonal experiment was used to optimize and obtain a set of optimal process parameter combination.Based on the simulation results,the forming die design and forming experiment were carried out,and qualified parts were obtained.The main conclusions of this paper are as follows:(1)The spatial structure of the front floor parts is relatively complicated.The preliminary forming simulation study shows that the defect of insufficient drawing is likely to occur after the stamping forming.This defect will seriously affect the rigidity of the product and affect the use of the front floor.According to the structural characteristics of the front floor,the variable strength double drawbeads are set,and the defect of insufficient drawing of the front floor is effectively controlled.(2)The influence of the blank holder force,die clearance and friction coefficient on drawing operation of the front floor was studied by numerical simulation.By increasing the blank holder force and the coefficient of friction,the flow resistance of the sheet can be increased.However,the blanking force and the coefficient of friction can not be increased all the time to prevent cracking of the front floor.Finally,the blank holder force and the friction coefficient were tentatively set to 650 kN and 0.15,respectively.When the die clearance is 0.80 mm,the maximum failure value of the front floor is the smallest,so the die clearance is tentatively set to 0.8mm.(3)The influence of blank holder force,die clearance and the friction coefficient on the springback of the front floor were studied by orthogonal experiment.The friction coefficient has the greatest influence on the springback of the front floor parts,followed by the die clearance,and the blank holder force has the least influence on the springback of the front floor parts.Combined with the simulation results of front floor forming,the optimal combination of process parameters was obtained through final optimization: the blanking force is 700 kN,the die clearance is 0.84 mm,and the friction coefficient is 0.15.The maximum springback value of the final part is 1.347 mm.The maximum failure is 0.756 and the maximum thinning rate is 28.1%,which meets the actual production requirements.(4)Based on the relevant data of numerical simulation,the die design of each operation of front floor part is completed and the forming experiment is carried out.The results of forming experiments show that the forming conditions of the parts after drawing,trimming punching and wedge trimming punching are consistent with the results of numerical simulation.Therefore,the accuracy of the numerical simulation study results was verified.