Patent ID: 6009734
Filing Date: 2000-01-04
Classification: B21D

Abstract:
A process for manufacturing at least one hollow section having cross-sectional expansions at ends thereof by using a forming tool that consists of two separable halves which form two hollow sections with cross-sectionally widened ends facing one another, comprising the steps of:widening and simultaneously upsetting at least one hollow blank in a continuous operation with an outside axially directed pressure force before the forming tool is in a closed condition to form a rotationally symmetrical bulging preform which approximates a desired end form of the at least one hollow section, the bulging preform being mirror-symmetrical relative to a transverse center axis of the at least one hollow section; and,in the closed condition of the forming tool, calibrating the formed blank obtained in the expansion upsetting operation with an internal pressure above an internal pressure during the widening and upsetting step to provide a final form of the hollow section pressed completely against sinkings in the two halves of the forming tool.