Finish sizing of thick walled steel tubes - by internal expansion of plastic sleeve with high pressure oil

摘要

A machine for the sizing of thick walled tubes of high tensile steel has a mandrel (3) fixed to the machine frame. A bush (4) mounted on the mandrel carries a sleeve (6) made of a plastic with a high elastic modulus. This sleeve is retained axially by a ring (11) which abuts against the shoulder (12) of the mandrel (3). High pressure oil is applied to the annulus (7) between bush (4) and sleeve (6). This pressure expands the sleeve radially and presses a ring of segments (15) (16) against the wall of the tube (23) which is, in turn, expanded. This expansion is limited by the outer sleeve (24).