Investigation of Manufacturing Processes of the Metallic CNG Pressure Vessels

CNG vessels are used in many vehicles.  Mass production of CNG pressure vessels requires exact understanding of process effective parameters.  In this paper, the numerical analysis has been used to study the manufacturing parameters.  The entire manufacturing processes, including deep drawing, redrawing and ironing, of an aluminum liner sample of CNG pressure vessel (without spinning) have been simulated by Finite Element technique.  The deep drawing process has been modeled by using flat dies.  Then, drawing force and wall thickness variations have been studied.  In order to achieve the final diameter of the liner, the redrawing process has been implemented in a flat die.  To obtain a uniform wall thickness, the ironing process has been simulated in two stages, and the required force and the change of wall thickness for each process have been recorded.  The results of this paper have been compared with the published results obtained by other researcher and found a good correlation between them.