An investigation on manufacturing process parameters of CNG pressure vessels

Mass production of CNG pressure vessels requires an accurate understanding of process effective parameters. In this paper, the finite-element method has been used to study the vessel manufacturing parameters. The FE model has been verified by experimental results. The entire manufacturing process, including deep drawing, redrawing and ironing, of an aluminum liner sample of CNG pressure vessels (without spinning) have been simulated. The deep drawing process has been modeled by using three types of dies: flat, conical and tractrix; then drawing force and wall thickness variations have been compared. In order to achieve the final diameter of the liner, the redrawing process has been implemented in a conical die. To obtain a uniform wall thickness, the ironing process has been simulated in two stages, and the required force and die angle for each process have been extracted. The result of this work presents an integrated perspective for decision-making on the manufacturing of CNG liners.