FI82157B - Cable with reinforcing element surrounding the cable core - Google Patents

Description

1 82157

Cable with strain relief elements surrounding the cable core

Separated from patent application 843 268.

5

The invention relates to a cable according to the preamble of claim 1.

It is known to embed string-like individual elements as strain relief elements in a cable sheath when compressed through a nozzle. This provides a good force-based connection to the sheath and the strain relief elements, so that the traction forces are kept away from the cable core without large initial elongations. Especially for optical cables, it is important that the tensile elements in the tensile load are fully functional before the initial elongation of more than 0.5% is created. On the other hand, the flexibility of such a cable is not satisfactory. The insertable strain relief elements interfere with the cable sheath when squeezed through the nozzle.

20 The problem with fixed cables is that when water penetrates the damaged area, it can move longitudinally through the strain relief elements. Furthermore, since it cannot be ignored that pressing the sheath through the nozzle creates 25 separate unfilled hollow spaces which form a bridge for the passage of water from the strain relief elements to the cable core, such cables are not sufficiently watertight in the longitudinal direction. Although the strain relief elements formed by gluing numerous fibers together are prevented from conducting their water-30, this makes the bendability of the cable even more difficult.

It is an object of the invention to form a cable of the kind mentioned at the beginning in such a way that the tensile forces, while maintaining good bendability, cannot adversely affect the core of the game, and in particular that the longitudinal water tightness is guaranteed.

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The solution is achieved by the features set forth in claim 1. Preferred embodiments of the invention are set out in the dependent claims.

Since the numerous strain relief elements made of thin, non-glued fibers 5 are completely surrounded by an inner and outer sheath of molten material, water penetrating at the point of damage and spreading along the lengths of the fibers cannot enter the cable core. Longitudinal spreading of water within the strain relief elements can be continuously or discontinuously impeded or prevented by sealing powder or by impregnating the fibrous elements with a gel-like substance. It is also possible to glue the fibers pointwise in the longitudinal direction at greater intervals at successive points, for example a cyanoacrylate-15 club. This prevents water from creeping longitudinally without compromising the bendability of the cable, such as through continuous gluing of the fibers.

Because the strain relief elements are distributed in a flat form around the core, small cable splits are obtained. Due to this and the sliding of the fibers against each other, the bendability of the cable does not become too difficult.

The use of a melt binder to surround the strain relief elements on all sides provides a force-based connection, especially with respect to the jacket-25 layer placed on it, because melting is achieved during the extrusion step of the die. Therefore, when installing the cable, conventional pull-up gloves that grip the cable sheath can be used.

When the strain relief elements seamlessly cover the entire circumference of the core 30, a tight barrier layer is formed against the outlet of the longitudinal water-conducting fillers of the cable core, such as petrolatum. In this case, the use of a polyamide-based melt binder is particularly advantageous because the polyamide is resistant to the action of petrolatum.

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A preferred embodiment of the invention is shown in the drawing.

The figure shows a cross-section of a cable core surrounded by strain relief elements according to the invention.

In the embodiment according to the figure, a first melt-adhesive layer 5 is pressed through the nozzle over the cable core 1. A layer 6 of numerous thin, parallel fibers is wound on it with a long thread pitch, for example by twisting several 10 adjacent individual bundles. .

A second melt binder layer 7 is again pressed over the fiber layer 6 through the nozzle. The melt binder layers 5 and 7 and the fiber layer 6 15 enclosed between them form a strain relief element for the core 1.

A cable sheath can be placed on the strain relief element by squeezing it through the nozzle. The hot-melt binder layer 7 adheres to the cable sheath.

Claims (10)

Cable with strain relief elements surrounding a cable core (1) consisting of a plurality of thin fibers parallel to each other, characterized in that the strain relief elements are formed as a layer (6) completely surrounding the cable core (1) consisting of a plurality of thin fibers sliding against each other. the fibers are long-threaded around the cable core (1), and that the layer (6) is interposed between the lower (5) and upper (7) fusible sheath layers. Cable according to Claim 1, characterized in that the melt binder layers (5, 7) are formed by extrusion. Cable according to Claim 1 or 2, characterized in that the melt binder layers (5, 7) are made of aromatic polyamide. Cable according to Claim 1 or 2, characterized in that the melt binder layers (5, 7) are made of polyethylene. 4 82157 Cable according to one of Claims 1 to 4, characterized in that the fibers are aromatic polyamide. Cable according to one of Claims 1 to 4, characterized in that the fibers are glass with a diameter of less than 30 μm. Cable according to one of Claims 1 to 6, characterized in that a sealing powder is continuously or discontinuously interposed between the fibers. Cable according to one of Claims 1 to 6, characterized in that the fibers are impregnated with a gel-like substance. Cable according to one of Claims 1 to 8, characterized in that the fibers are glued together at regular intervals in the longitudinal direction 5 82157 with a cyanoacrylate adhesive. Cable according to one of Claims 1 to 9, characterized in that the layer (6) is prayerfully compressed radially against the cable core (1). 6 82157