Patent ID: 6776953
Filing Date: 2004-08-17
Classification: B21D

Abstract:
Process of forming a hollow body comprising:providing a forming mold comprising an upper mold and a lower mold, the upper mold and the lower mold forming a mold cavity having a cross-sectional contour in a closed state of the forming mold, and the upper mold comprising a roller; placing the hollow body between the upper mold and the lower mold in an area of the mold cavity; preprofiling the hollow body by moving at least one of the upper mold and the lower mold into the closed state whereby the roller comes into frictional contact with a surface of the hollow body running at an acute angle with respect to a direction of movement of the at least one upper mold and lower mold; and forming the preprofiled hollow body into a final shape corresponding to the cross-sectional contour of the forming mold by applying a hydraulic internal pressure into the preprofiled hollow body and expanding the hollow body while the upper mold and the lower mold are in the closed state.