Tube Inversion: A Process for Obtaining Gross Expansions in the Diameter of Thin-Wall Tubes

Circumferential strains much in excess of the instability strains in internally pressurized tubes may be obtained by axially compressing the tube over a radiused die. As the tube walls slide over the curved parts of the die, simultaneous bending, stretching and unbending takes place. The resulting tube is of larger diameter, same wall thickness, and shorter in length.