Design of a Combined Redrawing-Ironing Process to Manufacture a CNG Pressure Vessel Liner

The liner of a compressed natural gas pressure vessel is manufactured by D.D.I. (deep drawing and ironing), which continuous process that uses deep to reduce the diameter billet ironing thickness billet. In second stage existing process, two steps have been performed separately with different dies, requires long processing time, high manufacturing cost, installation space. To solve above problems, this study suggests new using combined redrawing-ironing die. A theoretical formula calculate forming load was established verified finite element analysis results. load, maximum reduction ratio in stage, defects third were analyzed varying stage. results show number dyes (3 → 1), punch (394.1 mm 383 mm), time (39.8 s 20 s) obtained save production cost.