Apparatus and method for expanding and shaping tubular conduits

A tool for reshaping or expanding metal tubular material includes an expandable mandrel having a plurality of duplicate spreader segments held in a cluster by an elastic O-ring about a wedge-shaped cam, each of the segments including an external, curved wall having a curvature corresponding to a curvature of an external curved wall in every other segment such that when all segments are equally spaced a predetermined amount, they form a cylinder having gaps between adjacent spreader segments for contact against an internal surface of the tubular material for reshaping or expanding said tubular material. The wedge-shaped cam includes a plurality of external faces corresponding to a number of internal spreader segment faces sloped to converge toward a front, mandrel-insertion or forward end of the cam and shaped complementary to the shape of the internal spreader segment faces for sliding engagement of the segments over an adjacent external face of the cam. These segments are kept axially aligned during expansion to maintain a substantially uniform mandrel cross-section during tubular stock expansion.