Study On Springback Control Method Of Stamping Forming For Integral Front Floor Of A Passenger Car

Sheet metal stamping forming process is a metal pressure processing method,which has been widely used in various industrial fields including automobile manufacturing industry because of its advantages of high production efficiency,high material utilization and excellent forming quality.The metal material belongs to the elastoplastic material,and the stamping forming involves a complicated elastoplastic deformation process,so various forming defects such as wrinkling,cracking and springback are apt to occur in the stamping forming process.With the deepening of research on the defects of sheet metal forming and forming,the wrinkling and cracking problems have been gradually solved and deepened,and people have begun to pay more attention to the problem of forming springback control of stamping parts.The integral front floor is a typical interior panel of passenger car.Due to its large size,thin thickness and high middle channel structure,it is easy to cause forming quality defects,and the springback defect is particularly prominent.Whether the springback quantity can be controlled within a reasonable range will directly affect the subsequent assembly accuracy and vehicle quality.Aiming at the springback problem of stamping forming of integral front floor of a passenger car,this paper focuses on the forming springback control method of the part.The main research work are as follows:(1)Through the structural analysis of the front floor part,the difficulty of stamping forming was clarified,and the springback problem was one of the main defects of the forming of the part.Three possible forms of forming springback were analyzed: angle springback,the middle channel side wall curl springback and the overall torsion springback of the part.(2)By using the original data and finite element numerical simulation technology,the stamping process of front the floor part was preliminarily simulated and analyzed.It was found that there were no wrinkles and cracks in the part after forming,but the springback quantity of the parts was too large to meet the design accuracy requirements,so springback control was needed.(3)With the objective of minimizing the maximum free springback quantity,four process parameters(including blank holder force and three groups of drawbead resistance coefficient)that was easier to control in actual production were optimized by orthogonal test,which reduced the maximum free springback quantity of the part afterforming;On this basis,three iteration compensation corrections were made to the drawing die surface,so that the maximum restrained springback quantity of the part after forming was greatly reduced,which satisfied the design accuracy requirements;Combining the above two springback control methods,a trial production of the front floor part was carried out,which verified the effectiveness of the two springback control methods.(4)The relationship between modal analysis and springback control was analyzed,and the free modal analysis of the front floor part was proposed.The structural stiffness of the part was improved by increasing the low-order modal natural frequency,so as to control the springback: Firstly,based on a certain theoretical analysis,the stiffeners in the floor area of the part was optimized preliminarily,so that the low-order modal natural frequency of the part was increased and the springback quantity after forming was reduced;Then the topography optimization was used to optimize overall the stiffeners of the part,which greatly improved the natural frequency of the low-order modes and had excellent control effect on the forming springback.