Abstract:

The kinematically admissible velocity .field of ironing with contoured die of equal strain rate has been first put forward in this paper. According to the upper-bound theorem, the influence of technological parameters on the average pressure of punch during the ironing with contoured die of equal strain rate is studied. Meanwhile, with the aid of the minimum energy principle, the optimum height of contoured die (H_opt), which is an essential variable for ironing with contoured die of equal strain rate, has been calculated. The calculated results show that; reduction in thickness, work-hardening effect and friction existing between billet and die are the main factors affecting the average pressure of punch; reduction in thickness, outer dimension of billet (R_e) and friction existing between billet and die are the essential variables for determining the value of H_opt, The experimental results of H 62 (corresponding to ASTM 280) and H 68 (corresponding to ASTM 260) show that the analytical results agree well with the experimental results.

Key words: ironing, contoured die of equal strain rate, upper-bound theorem