Effect of blank shape and hydraulic counterpressure on deep drawing limit of rectangular shells

摘要

In the deep drawing of rectangular shells with various side length ratios l{sub}(P1)/l{sub}(P2), the effects of rectangular blank shape and hydraulic counter-pressure on the height limit of deep drawing are examined. In the deep drawing of rectangular shells by both conventional drawing and hydraulic counter-pressure drawing, when a rectangular blank with an increased length L{sub}1 parallel to the minor side of the shell is used, the height limit of deep drawing increases. That is because the increased L{sub}1 decreases the difference between the material flow speeds at the straight side flange and the corner, and mitigates the inflow hindrance at the corner flange by increasing the inflow at the straight side flange. The smaller the l{sub}(P1)/l{sub}(P2) of the shell shape is, the larger the forming limit h{sub}(max)/l{sub}(p1) of the rectangular shell is. When an appropriate blank shape with the increased L1 is used, hydraulic counter-pressure deep drawing yields a height limit 1.21.8 times greater than conventional deep drawing. In deep drawing using a rectangular blank with an appropriate length of L{sub}1, h{sub}(max)/l{sub}(P1) = 1.80 is obtained by conventional drawing, and h{sub}(max)/l{sub}(P1) = 2.20 by hydraulic counter-pressure drawing.