PLASTIC DEFORMATION TECHNOLOGICAL PROCESS FOR PRODUCTION OF THIN WALL REVOLUTION SHELLS FROM TUBULAR BILLETS

摘要

This invention refers to a process of plastic deformation for production of thin wall revolution shells from tubular billets. The process consists in end-forming a hollow circular section billet, which can be composed of a multi- layered assembly, by using sharp edge internal domed shaped molds (1) that are guided externally by a constraining sleeve (3).This mold-sleeve tool can be assembled in a press in order to generate the pressure forces necessary for the forming process. The plastic deformation can result in thin walled spheres or cylinders with domed ends. The resultant revolution shells have two opposite (polar) circular openings. Both the shell's length as the polar hole diameter is mainly determined by the billet's initial dimensions and mold (1) domed geometry. An innovative flexible inner mandrel may be introduced to considerably improve overall shell characteristics, allowing reduction of shell polar opening diameter, giving control of along-meridian thickness, solving typical thin wall forming problems such as buckling, wrinkling and ruptures and improve both outer and inner surface quality. This mandrel can be discarded and/or recycled after forming. This invention enables a low-cost and high-rate process for production of structural revolution shells capable of being used as high-pressure vessels.