Patent ID: 6446321
Filing Date: 2002-09-10
Classification: B21D,Y10T

Abstract:
A process for manufacturing double-walled pipes to be connected together to form a double-walled pipeline, comprising:providing a coaxial arrangement of an inner tube and an outer tube space having a cylindro-annular space extending in the axial direction therebetween to form a double-walled pipe; axially retracting said outer tube with respect to said inner tube to reveal an. inner tube end portion, wherein an adjacent end wall portion of said outer tube defines a connecting area; gradually applying pressure concentric to said connecting area, thereby deforming the adjacent end wall portion by reducing an outer diameter of the outer tube end wall until an inner surface of said end wall abuts an outer surface of said inner tube end portion, thereby closing only an end of said space so that substantially the remainder of said space remains, said pressure being applied by arranging a plurality of bars spaced circumferentially around said connecting area and tilting said plurality of bars, wherein each of said bars moves along a plane extending substantially radially outward from, and in alignment with, the center axis of a crown, said crown fixed with respect to said outer tube and to which said bars are attached in an articulated manner.