| 摘要 |
A grooved tubular protective sheath (10) with a slot and a longitudinal flange. In particular, the flange (24) is provided on one edge (16) of the slot substantially at the bottom of the grooves (12) and positionable under the other slot edge (17). The grooves are closed at the edges (16, 17) of the slot by transverse walls (22). A method for manufacturing a grooved sheath includes extruding and molding an annular sheath with a longitudinal flat strip level with flute edge hollows, cutting the flat strip along one of its flute edges to form a tongue that is integral only with the other flute edge. The method further includes heating the sheath and cooling it, while passing it between cones or calenders to bring the flute edges together, whereby the tongue passes between the cut edge. A device for making a grooved sheath includes a molding machine with two series of symmetrical parallel shells. Internal faces of the shells are semi-cylindrical and ribbed transversely with a series of rainbow-shaped flutes forming a crenellated profile with flute hollows and flute ridges. Each shell in one of the series has a protuberance in form of a thin flat strip situated level with the flute ridges, wherein the strip is aligned from one shell to the next. |
