Deep Drawing of Circular Sheet Metals with Rubber Rings : 2nd Report, The Case of Repeated Drawing Operations

Abstract

The drawing limits of mind steel and aluminum sheets were examined for the case of repeated drawing operations in which the blank was deformed incrementally as the rubber ring was repeatedly loaded and unloaded. The drawing condition used was base on the optimum one for the first drawing operation clarified in our 1st report. The obtained drawing ratio was 2 for mild steel, 3 for hard aluminum and 6 for half-hard and soft aluminums. When the work hardening of the blank was diminished by intermediated annealings, a maximum drawing ratio of 12 was achieved for soft aluminum. The strain distribution, shape and a surface roughness of drawn cups were also examined. Furthermore, the relation between the height of the drawn cup and the number of drawing operations was discussed for the case of using either a vulcanized natural rubber or a polyurethane ring and was compared with the data reported by N. A. Maslennikov.