Cable, especially for installation into a canal or a pipe

A cable, which is suitable for installation into a canal or pipe, has a cable core (ZE, OA) and a cable jacket (KM 1 , KM 2 ) surrounding the cable core. The cable jacket (KM 2 ) has discrete elevations (LSA) on a base material of the cable jacket, which are formed as longitudinal strips stretching in the longitudinal direction of the cable (OC 1 ). By providing the longitudinal strips (LS), the gliding friction during insertion of the cable into a canal or pipe is reduced, so that the cable can be inserted with comparatively lower force into the canal or pipe.

FIG. 1 shows an optical cable OC 1 , which has a central element ZE made in this sample of GFK material. Optical cores OA in the form of bundles are stranded around this central element ZE. Each of the bundles OA has a multitude of optical fibers LF, which are imbedded in a filling compound. Around this cable core consisting of central element ZE and optical core OA a multi-layer cable jacket is applied, which surrounds the cable core. The cable jacket has a foamed layer KM 1 and a skin layer KM 2 . On the base material of the skin layer KM 2 discrete elevations in the form of longitudinal strips LS are applied which are formed a continuous longitudinal strips and stretch along the longitudinal direction either in a straight or helix manner. The inner layer KM 1 is made from approx. 40% foamed MDPE plastic, the outer skin layer KM 2 from pure MDPE plastic. The longitudinal strips LS are manufactured from MDPE plastic with embedded silicone. The cable jacket and the longitudinal strips arranged on it can be produced in one work process by co-extrusion or strip extrusion. The embedded silicone in the longitudinal strips significantly reduces the gliding friction of the cable, i.e. the gliding characteristics of the total cable OC 1 are significantly improved when pulling it into a canal or pipe. The cable OC 1 in the present construction has a diameter of d&equals;9 mm. For the purpose of weight reduction of the cable, 20-70% hollow space volume is included in the foamed layer KM 1 . The foaming favors easier deformation of the cable surface and leads therefore to a certain form determination when using profiled insertion caterpillars or insertion wheels for inserting a cable into a pipe system. A sufficiently good gripping capacity or adhesion friction, respectively, to the cable is thus achieved, otherwise the friction between the cable and the pipe is very low due to the longitudinal strips. In this way, the forces needed for insertion are not too great, so that large cable lengths can be inserted into the pipe. FIG. 2 shows a further construction of a cable according to the invention. The cable OC 2 is similar in its essential elements to the cable OC 1 shown in FIG. 1 ; however, the cable jacket in the cable OC 2 is formed in three layers. Such a construction can be advantageous for certain cable types and requirements. The cable OC 2 has a three-layer jacket in the form of a so-called “skin-foam-skin” jacket. Here the innermost layer KM 3 and the outermost layer KM 2 are solid and in the form of a skin layer.