A study on the springback in the sheet metal flange drawing

The flange drawing process is used to make flanges from the sheet metal blank using the die, punch and blank holder optionally with the supporter. This process is being applied in many sheet metal industries. One of concerns of this process is that the flanged section formed is mostly not parallel with the original blank due to the springback occurrence, which could affect the quality of the formed part. This study has focused on the evaluation of springback occurring in the sheet metal flange drawing process by controlling some process factors like the punch corner radius (PR) and die corner radius (DR), the blank-holding-force (BHF), the supporting-force (SF), the lubrication and so on. The springback phenomenon in the flange drawing process has been studied first using the finite element method (FEM) in order to understand what the main causes of springback are. The distribution pattern of local x-component of stress along the longitudinal direction of the blank has been revealed to be very important in predicting the final shape of the flange. This fact has been backed up by the experimental results carried out with the developed test dies. The Taguchi table L18 has been used to determine which of the process factors of the flange drawing is the most influencing to make the flanged section parallel with the original blank in spite of springback occurrence. The results show that the punch corner radius (PR) is the most important factor of the process.