Improved flexible mandrel for bending hollow articles.

摘要

The invention comprises a flexible mandrel for insertion into and removal from a hollow member, said mandrel being adapted to provide support for the walls of the hollow member in the process of bending the member, the mandrel comprising a plurality of elongated individual hoses disposed together in a side-by-side manner to form a unitary, elongated mandrel structure, said hoses being capable of expanding in cross section when a fluid is directed to them under pressure at a predetermined pressure value and contracting in cross section when the pressure value is lowered to or below a predetermined value, the cross-sectional expansion and contraction of the hoses being effective to expand and contract the cross-sectional area of the mandrel structure.