Rastuća sila držanja kao tribološki faktor pri čistom dubokom izvlačenju prevučenih limova u uslovima nemonotonog deformisanja

Abstract

Blank holding force (BHF) is normal force for friction on the work part flange and very significantly influences the deep drawing process. Presented in the paper are analyze of variable increasing BHF influence during the process. The experimental researches were performed on a special laboratory computer device. Two type of drawing process are realized: monotonous and two−phased nonmonotonous with uniaxial tension at first phase. Influence of increasing BHF, forming history and contact conditions (dry surfaces, use of oil and use of foil with oil) monitored are through: strain distributions (thick strain and sheet plane strains), change of forming limit, drawing force dependence on punch travel and work piece macro properties: drawing depth, appearance of wrinkles or tears. Observed is important possibility of influence on deep drawing process course and results, by using increasing BHF.