| 摘要 |
A tube 5 for eversion into a passageway 6 is formed with one or more circumferential folds (concertina folds) 7 along its length so arranged that on eversion of the tube into the passageway each portion is turned inside out. During the eversion the evened part 5c of the tube remains stationary while the non-evened 5d part of the tube advances along the passageway. An annular fold 5b between the everted and non-everted parts travels along the passageway and each concertina fold opens as it approaches the annular fold. The configuration of the folds, including shape, spacing and/or number per unit length may be varied in order to vary the rate of advancement of the non-everted part. The folds may be formed by a thermosetting process and are arranged to reform as the tube is withdrawn from the passageway. Each concertina fold may be maintained in its closed non-everted state by an adhesive composition or by a closely fitting sheath. The tube may be suitable for insertion into a tract of the human body. |
