Mold for forming a groove in a tube

摘要

An elongated flexible tube that constitutes an insert part of an endoscope. The flexible tube comprises: a spiral tube made of a precipitation hardening metal and having a groove which is recessed inwardly from the outer surface of the tube, the groove extending in a straight line along the axis of the tube, the spiral tube being subjected to age hardening process after a solid solution treatment; a braided-wire tube formed by weaving fine metal wires into a braid, the braided-wire tube being closely fitted over the outer surface of the spiral tube; and a flexible skin closely and watertightly fitted over the outer surface of the braided-wire tube.