CABLE COATING STRUCTURE

The present invention concerns a cable coating structure insertable into ducts, for example underground ducts or inside underground trenches into which electric or fibre optic cables or cables of another type may already have been inserted. The system of sub-tubing the ducts that transport cables has already been used in the telephone sector through the use of braiding and through the use of more plastic material cables joined one to another. Such systems of known type mainly present the drawback of not being reliable due to the fact that the cables, during the insertion operations in the partially occupied pipings, may remain stuck into the cable's sheath already present or may adopt particular positions, for example partially arranged like a helix or partially wound around the sheath of the main cable. Furthermore, in more critical cases, the operation may become impossible in pipings in which the free space to insert a new sheath is limited. The Applicant has seized the problem of making a sheath for cables to be inserted into even partially used pipings which does not tend to get stuck during the insertion operation in the piping itself and which is adequately arranged therein.

The Applicant has solved such a problem by making a cable coating structure formed by a plurality of ducts or sheaths longitudinally linked to each other (made integral with one another) through flexible elements . An aspect of the present invention concerns a cable coating structure suitable to be inserted into a tube comprising at least two ducts into which such cables may be inserted characterised in that such at least two ducts are made longitudinally integral with one another through flexible fitting elements.

The characteristics of the invention will be more obvious from the following description and from the accompanying drawings, in relation to an illustrative but non limiting embodiment of the present invention in which:

• in figure Ia, a section of cable coating structure according to the present invention is depicted in perspective view;

• in figure Ib, a front view of the cable coating structure's end according to the present invention is depicted;

• in figure 2, the coating structure inserted into a piping in which a sheath and a cable are pre-existing is depicted; • in figure 3, the coating structure inserted into an underground trench is depicted;

• in figure 4, the cable coating structure having a sheath occupied by a cable co-extruded with it is depicted;

• in figures 5a and 5b, two possible arrangements of a five-duct structure inside pipings are depicted.

In reference to the mentioned figures, the cable coating structure comprises a plurality of ducts 2,2' or sheaths longitudinally linked to each other (made integral with one another) through flexible elements 3. Electric cables, fibre optic cables, thin telephone cables, etc. may be inserted into such ducts, for example through the traditional techniques of blowing. Preferably, there are at least three ducts, even more preferably, there are at least five ducts. Moreover, the central duct 2' of the structure may have a larger diameter compared to the diameter of the other ducts. The thickness of the flexible elements is not uniform, that is, it is advantageously diversified. In particular, the cross section thereof is formed so as to preferably present a central tapering 31 in relation to the opposed ends 32 that are connected to the ducts. This, in addition to the material of which such elements are made, further contributes to increasing the overall flexibility of the structure.

In fact, the central tapering eases the bending of the flexible elements and therefore the bending of the entire structure.

The flexible elements constituting the cores of the coating structure of the cable are preferably made of soft, synthetic or natural high-deformability rubber materials in order to give the structure a significant plurality of deformations. The ducts may be made, for example, of plastic material with particular wear resistance characteristics, as a result of the dragging linked to the laying of the housing tube, and good deformability to allow the above said deformations. The ducts, in order to ease the simplest insertion of the cables in a conventional laying or with fluids, may hold in their inner portion a layer of extremely fluid lubricating material and with antidesiccant properties, i.e. which maintains lubrication characteristics over time. The ducts and the flexible elements are made integral with one another by a process of co-extrusion which leads to the making of the manufactured article so that the various materials are made integral by means of an intimate penetration. The integrally made ducts may adopt a different radius of curvature in the cross section, in order to adapt to the layout of the main tube. In figures 5a and 5b, two

possible arrangements of the structure inside a tube T are depicted. In figure 5a, the structure adopts an arched form thanks to the flexibility of the flexible fitting elements between the ducts, while in figure 5b the structure adopts a semi-circular form. The flexible fitting elements also allow for the structure to longitudinally wind like a helix inside the main tube T, thus permitting transit also at curves thereof. The flexible fitting elements allow for the ducts of the integral tube structure to adopt a different radius of curvature in the cross section, in order to adapt to the layout of the main duct.

For its easiness to conform to the specific needs, the structure according to the present invention, or also two or more associated structures, for example placed side by side or stacked, may also be inserted into an underground trench S as depicted in figure 3. Furthermore, according to a characteristic of the present invention, the possibility of separating the ducts is given to the structure. In fact, the flexible elements are easily separable and thus allow for bringing part of the structure into other tubes, at draw pits or drain wells, in order to supply, for example, users located in different places. Furthermore, in a duct, for example inside the central one of the structure, a cable C may be advantageously

preinserted during the construction phase of the structure, a power cable, for example, for requirements linked to remote power supply. In fact, the structure may already be equipped with a power cable, in case research has been conducted for the dimensioning of the cable itself.