FR2571155A1 - Process for producing a fibre-optic cable and cable obtained by this process - Google Patents

Abstract

A cable according to the invention includes, diagrammatically, a cylindrical central support 1 the periphery of which has helical grooves 2 in which optical fibres are housed. A first polyester tape and a second tape coated with hot-melt are wound helically around the support.

Description

Method for producing a fiber optic cable and cable obtained by this method
The present invention relates to a method for producing a fiber optic cable, and a cable obtained by this method.

 Such a cable schematically comprises a cylindrical central support whose periphery has generally helical grooves in which are housed optical fibers. A plastic tape, for example polyester, is wound in a helix around the support provided with the fibers. It can be seen that during use the ribbon undoes at the ends of the cable; in these places the central support and its fibers are no longer protected. It can also happen that the polyester tape is displaced relative to the support, when the cable is threaded through a pipe.

 The present invention aims to avoid these drawbacks.

 The subject of the present invention is a method of producing a fiber optic cable, comprising a grooved cylindrical central support in which optical fibers are housed, method according to which a first ribbon is wound helically around said support provided with its fibers. plastic material, characterized by the fact that one side is coated with a second plastic tape with a thermoplastic adhesive, which is then helically wrapped said second tape around said first tape so that said coated side found against said first ribbon, and that we pass the assembly through an oven to secure the two ribbons.

 The material of said first ribbon and of said second ribbon is chosen from plastic materials capable of withstanding the heat treatment of heat sealing, such as polyester, polyamides, polyethylene terephthalate, polyimides.

 The thermoplastic adhesive is a "hot melt" of polyamide, EVA (ethylene-vinyl-ethyl acrylate) or EEA (ethylene-ethyl-ethyl acrylate) type.

 The invention also relates to a fiber optic cable obtained by the above method.

 Other characteristics and advantages of the present invention will appear during the following description of an embodiment of the method according to the invention.

 The single attached figure is a very schematic view of an installation. We see a cylindrical support 1 in metallic or composite material having helical grooves 2 in which are housed optical fibers (not shown). The support 1 moves in translation in the installation according to the arrows 3. A first inclined rotating wafer 12 mounted on a rotating assembly 30 carries a ribbon 10 of polyester. The rotation of the crew 30 around the axis of the support 1 has the effect of providing the support 1 furnished with its fibers of non-contiguous turns it of tape 10. A second inclined rotating wafer 22, also mounted on the rotating crew 30, carries a polyester ribbon 20 pre-glued with a material of the "hot-melt" type. The rotation of the crew 30 has the effect of surrounding the turns 11 of turns 21 of ribbon 20, the face of the ribbon 20 coated of one. cord of nholt-melt "-located against the turns 11.

Preferably, the helical windings of the strips 10 and 20 are made so that the turns overlap to protect the support more effectively.

 The cable 24 thus produced passes through a heating enclosure 40 which allows the sudden melting of the "holt-melt". The very rapid solidification of the product at the outlet of the oven allows the turns 11 and the turns 21 to be joined. At the outlet of the oven, cable drive tracks 41 and 42 have been illustrated.

 Of course the example which has just been described is not limiting.

The grooves containing the fibers can be oriented along generatrices of the cylindrical support. The widths of the ribbons can be different. The materials of these ribbons are chosen essentially as a function of their resistance to the heat treatment which they undergo in the heating chamber 40. Instead of polyester, polyamides, polyimides or polyethylene terephthalate can be used, for example.

As a product known under the name of "hot-melt", it is possible, for example, to take a polyamide, E.V.A. or E.E.A.

The method according to the invention makes it possible to maintain the turns 11 on the central support 1 even at the places where the cable is cut. The use of a reel of ribbon pre-glued with a hot-melt does not require gluing when the turns 21 are wound around the turns 11. There is therefore no risk of accidentally introducing the glue in the grooves of the support containing the fibers rigid immobilization of the fibers in their grooves would indeed be extremely harmful in the event of traction of the cable.

Without departing from the scope of the invention, any means can be replaced by equivalent means.

Claims (5)

1 / Method for producing an optical fiber cable, comprising a central cylindrical grooved support in which optical fibers are housed, method according to which a first ribbon of plastic material is helically wound around said support provided with its fibers, characterized by the fact that it is coated on one side with a second strip of plastic material with a thermoplastic adhesive, which is then helically wrapped in said second strip around said first strip so that said coated side is against said first strip, and that we pass the whole in a hot air oven to secure the two ribbons. 2 / A production method according to claim 1, characterized in that the material of said first ribbon and said second ribbon is chosen from plastic materials capable of withstanding the heat treatment of heat sealing. 3 / A production method according to claim 2, characterized in that said plastic materials are chosen from polyester, polyamides, polyimides, polyethylene terephthalate.  4 / production method according to one of claims t and 2, characterized in that said thermoplastic adhesive is a "hot melt", of polyamide EVA (ethylene-vinyl-ethyl acrylate), or EEA (ethylene) type -ethyl-ethyl acrylate). 5 / Fiber optic cable obtained by the method according to one of the preceding claims.