STUDY OF DEEP DRAWING PROCESS AND ITS PARAMETERS USING FINITE ELEMENT ANALYSIS

Abstract

Deep drawing is a sheet metal forming process in which a flat blank is deformed to form cylindrical cups. It is a widely popular technique in the automobile, aerospace, and packaging industries. A considerable amount of study has been already done in this field, but there is still a huge scope for further exploration. The objective of this research work was to demonstrate the overview and to study the various parameters influencing the drawability of the deep drawing process. The quality and drawability of deep-drawn products majorly depend upon parameters such as blank position, speed, sheet thickness, clearances, coefficient of friction between die-sheet and punch-die, blank holding force, strain rate, temperature, etc. For this purpose, the deep drawing process was modelled and simulated in Ls-Dyna PrePost (R) V4.6.17 finite element analysis software. AA6082-T6 material was taken into consideration which was later annealed to attain higher elongation. Further, to predict the accurate material behaviour for the AA6082 Barlat-3 parameter anisotropic yield criterion was utilized. The Barlat material parameters and constants were determined by the tensile and anisotropy test. The results revealed that annealing increased elongation by 15% which was earlier in the range of 4-5%. The thickness in the flank region was increased as it experiences two opposite natures of stress. Additionally, as the sheet thickness decreased, there was an increase in blank holding force which was required to remove wrinkling. With the rise in coefficient of friction, there was a decrease in sheet thickness at the wall section. It was concluded that LDR increases with an increase in sheet thickness, coefficient of friction between punch and sheet, and die radius. Thinning resistance is more in isotropic material as compared to anisotropic materials which will eventually lead to deeper cups Also, LDR decreases with an increase in punch speed, blank holding force, friction between die and sheet, and punch radius. The deep drawing model also experiences high strain rates at a certain temperature during the process which is not taken into consideration during the Barlat model. Thus, to predict the combined behaviour of strain, strain rate, and temperature Johnson-Cook model is used for material characterization.