Analysis of Thin Sheets Deformation with Circular Holes at Flanging Process

Hole flanges are important functional elements in many sheet metal parts. They provide stiffness, allow for positioning and fixation, they guide cables etc. Hole flanging operations in sheet metal parts are typically performed using dedicated tooling. Recent publications proved that hole flanging by incremental sheet forming (i.e. incremental hole flanging) is an interesting alternative to the traditional operations with dedicated tools. In incremental hole flanging, limit hole expansion ratios of up to ۴ were observed which are much larger than the typical expansion ratios of around ۲. Conventional hole-flanging is a forming process used to manufacture circular or asymmetric flanges. In this process, a holed sheet, rigidly fix to a die with a blank holder, is plastically deformed mainly by bending and circumferential stretching with a punch. In hole-flanging a flat sheet with a pre-cut hole is formed by deep drawing process which produce progressively produces whit a smooth, round flanged lip.The theoretical analysis of flanging process of circular holes in thin plates taking into account the interconnected changes of a thickness and deformation hardening is carried out. Possibility of definition of current values of strains in non-stationary processes of forming is shown. In process of flanging the co-ordinate of the material element differentiating area of compression and a stretching in radial direction is defined.

کلیدواژه ها:

Sheet Metal Forming ، Thickness Changes ، Work Hardening ، Flanging