Importance

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Abstract

A method of joining a tube to a flange or wall member includes the steps of moving a plurality of circumferentially spaced workpiece contact surfaces into controlled pressure contact with the inner surface of a tube and maintaining a force against the inner tube surface sufficient to form an outer surface of the tube to a predetermined shape with respect to an opening surrounding the tube. The apparatus for expanding the tube has a plurality of radially movable segments, each of which have a pair of circumferentially offset and longitudinally spaced workpiece contact surfaces disposed thereon. The method and apparatus advantageously expands a tube by an amount sufficient to form a secure mechanical joint with a flange or wall member irrespective of nominal variations in the tube diameter and wall thickness. Furthermore, the method and apparatus form a uniformly smooth finish on the internal surface of the tube thereby eliminating the need for post-forming treatments to remove undesirable surface particles.

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First Claim