Method for manufacturing a flexible tube for an endoscope

摘要

A flexible tube for use in an endoscope comprises a flexible basic tubular core structure and a homogeneous thermoplastic synthetic resin tube bonded to the outer surface of the tubular core structure to form a coating layer by positioning the synthetic resin tube tightly over the basic tubular core structure with a contact pressure therebetween and heating the synthetic resin tube to a temperature higher than a softening point of the thermoplastic synthetic resin forming the same. A flexible tube having flexibility which varies in a step-wise manner from one end of the tube to the other is obtained by integrally bonding as a whole two or more homogeneous thermoplastic synthetic resin tube sections formed of respective resin materials having different hardnesses to the outer surface of the tubular core structure to form a coating layer in an analogous manner. The ends of adjacent tube sections substantially abut each other and upon heating the tube sections to a temperature higher than a softening point of any one of them, the regions of the respective pairs of abutting tube section ends are heated to a temperature substantially near a melting point of the tube section having the higher melting point to successively fuse the respective pairs of abutting tube section ends together.