Studies on Blank Holders and Drawbead Design of Complex Sheet Metal Parts

Abstract

The flow of material into the die cavity is a major aspect in the stamping process to newlineimprove the quality of the part. Flow is managed by adjusting the blank holder force, newlineblank shape, and drawbead geometry. Sheet metal forming research address many newlinefracture issues while drawing smaller and larger parts, the majority of large newlineautomotive components are drawn using equipment with drawbeads and blank holders newlineto provide additional restraining forces. When applying drawbeads and blank holder, newlineit is important in order to avoid breakage, scrap production, a high number of newlineexperimental die trials, and repetitive grinding of drawbeads. newlineThe aim of the research is to develop simple guidelines based on finite element newlinesimulations to predict and prevent fracture and wrinkles in a stamping process with newlinethe application of drawbeads and blank holder, thereby minimizing the need for newlineexperimental die trials and scrap production by carrying out optimizing location of newlinecircular drawbead for symmetrical parts like hemispherical cups using numerical newlinesimulation and comparing the results with standard available literature. The same newlineprocedure is adapted for different blank shapes like circular, rectangular, and newlinehexagonal shapes to find the best thickness at the bottom of the cup after deformation. newlineFurther work is carried out to calculate the drawbead restraining force by developing a newlineMatlab programme using the Stoughton model and predicting the drawbead forces for newlinecircular and steeped drawbead. Next is to optimize the circular and rectangular newlinedrawbead geometry with blank holder force to predict the percentage of thinning and newlinedrawbead restraining force during cup formation by performing a Taguchi method and newlinefinite element simulation using Hyperform-14 software. The thickness and drawbead newlineforce are predicted using a linear regression model, and the findings are confirmed newlineusing a conformation test. The values obtained from numerical simulation are in good newlineagreement with literature data. For non-symmetric parts such as the reinforced inner newlinesid