Duboko izvlačenje pri promenljivoj sili držanja i složenoj istoriji deformisanja

Abstract

In this paper results of experimental investigations of galvanized sheet metal zinc coated at one side (marked TyZnI) will be given. Material is 0,8 mm thick. Work piece is of a cylindrical geometry with diameter 50 mm. Blank diameter is 50 mm. Blank diameter is 110 mm. For that geometry, variable holding force (VBF) dependence was obtained by empirically−analytical procedure. Functions were obtained at given condition of constant specific holder pressure (VBF decreasing dependence). In the first case, VBF was applied, with change of contact conditions (dry, oil, and oil plus polyethylene foil) without strain history change (one phase procedure). In the second case, two phase procedure was performed. At first phase sheet metalhas undergone uniaxial tension towardsrolling direction. At the second phase, out of the strained sheet metal blanks were cut out for the operation of deep drawing. The effects of the VBF and variable strain history influence are monitored through principle plain strains distributions, thinning strain distributions, depth and drawing force. In the conclusion we should emphasise that decreasing VBF shows obvious advantages in case without strain history change. With tension at the first stage, decreasing holding force does not bring to improvement concerning the drawing depth, but more uniform thinning strain distributions is obvious.