JPS5926169B2 - Bend part of communication cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication cable bending section that facilitates bending within a manhole or the like.

FIG. 1 is a sectional view showing how a normal cable connection section is installed in a manhole.

In the figure, 1 is the inner wall of the manhole, 2 is the underground duct where the cable is laid, 3 is the laid cable,
41. ri is the connection part.

The cables 3 drawn into the manhole from the duct 2 are bent and connected to each other at a position close to the side wall of the manhole.
The connecting portion 4 is fixed.

If the bending radius generated in the cable becomes smaller than the permissible limit (generally six times the outer diameter of the cable), there is a risk that the cable jacket will buckle and be damaged.

In addition, the cable jacket becomes flat and oval, putting pressure on the core wires.
In particular, in optical cables and coaxial cables, the mechanical strength of the core wire is low, so the transmission characteristics deteriorate.

In addition, the cable jacket is subject to significant strain and environmental stress cracking can occur if the cable is submerged in surfactant-containing water.

For this reason, it is not possible to install large diameter cables in small manholes, and depending on the manhole size,
There was a drawback that the outer diameter of the cable that could be laid was restricted.

In order to eliminate the conventional drawbacks, the present invention provides a communication cable with a sheath-removed portion from which the sheath is removed, and a cylindrical cushioning material is provided on the sheath of the communication cable to bridge the sheath-removed portion. A metal flexible tube having a rust-preventing function is provided at a position corresponding to the jacket removed portion of the buffer member, a fixing member is connected to the front and rear of the flexible tube, and the flexible tube is Wrap a heat-melt adhesive tape over the fixing member of the pipe, cover the wound heat-melt adhesive tape with a heat-shrinkable tube, heat it, and attach the flexible tube and buffer member to the outer sheath of the communication cable. Its purpose is to enable communication cables to be laid without being restricted by the cable's outer diameter, even in narrow manholes, to minimize the effect on transmission characteristics caused by bending the core wire, and to prevent corrosion. .

The present invention will be explained based on the drawings.

FIG. 2 shows a sectional view of a bent portion of a communication cable according to an embodiment of the present invention.

In the figure, 3a denotes a communication cable jacket (hereinafter referred to as a jacket).

], 3b is a core wire, and 5 is a flexible tube portion s5a with a wall thickness of 0.2 to 2
An airtight bellows-like flexible tube made of stainless steel or other metal coated with anti-rust plastic, formed into a bellows shape with a pitch of 1 to 50 mm%,
5b is a cylindrical buffer member made of urethane foam to protect the core wire 3b, and 5c is a smooth cylindrical buffer member made of metal fixed to the flexible tube 5a by welding or the like to improve adhesion with the adhesive material. The fixing member 6 is a hot-melt adhesive made of a mixture of an acid-grafted modified ethylene ethyl acrylate and a blend of ethylene ethyl acrylate, which has adhesive properties to both the metal fixing member 5c and the polyethylene of the outer sheath 3a. 7 is a heat-melting adhesive tape dotted with a temperature indicating material that changes color at 120 to 165°C, and 7 is a heat-shrinkable tube made of cross-linked polyethylene.

Next, the configuration of the bending portion of the communication cable of the present invention will be explained.

The outer sheath of the portion of the communication cable to be bent is removed to provide an outer sheath removal section 3A, and the outer sheath removal section 3 is placed on the outer sheath removal section 3A.
A cylindrical buffer member 5b, which is longer than the axial length of A, is coated on the outer cover 3a of the communication cable so as to be bridged, and a cylindrical flexible tube is placed on the buffer member 5b at a position corresponding to the outer cover removed portion 3A. 5a are arranged in close contact with each other, and metal fixing members 5c are fixed by welding or the like on the front and rear of the flexible tube 5a.
and the fixing member 5c of the flexible tube 5a, and after winding the hot-melt adhesive tape 6 on the fixing member 5C and the outer sheath 3a of the communication cable 3, the heat-shrinkable tube 7 is covered and the hot-melt adhesive tape is By heating with a heater until the temperature indicating material 6 changes color, the heat-shrinkable tube 7 is shrunk and the hot-melt adhesive tape 6 is melted, thereby fixing the fixing member 5c of the flexible tube 5 and the cable jacket 3a. do.

FIG. 3 shows an application example in which the folding section of the present invention is combined with a jacket connection section.

A flexible tube section 5 is used with an auxiliary lead pipe 5d fixed to the end on the side of the core wire connection section 8, and a connection between this and the main lead pipe 9 that covers the core wire connection section 8 is fixed by a lead worker 10. .

Note that if the mechanical strength (collapse) is low and moisture permeation can be ignored, a bellows-shaped tube made of plastic can be used.

As the bending section of the present invention uses a bellows-shaped tube with excellent flexibility as described above, the bellows-shaped tube can be used not only in manholes but also in places where small bends are required. The cross section is always kept circular and no compressive force is applied to the core wire, so even large diameter cables can be laid with a small bending diameter.The flexible tube is made of stainless steel or rust-proofed metal. Effects include being able to prevent corrosion due to accumulated water in manholes, making efficient use of existing equipment, and being able to install large (long) connections.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional cable connection part in a manhole, Fig. 2 is a sectional view of a bent part of a communication cable according to the present invention, and Fig. 3 is an application of the present invention connected to a jacket connection part. An example cross-sectional view is shown.

Claims (1)

[Claims] 1. A communication cable is provided with a sheath removal section where the sheath is removed,
A cylindrical buffer member is coated on the outer sheath of the communication cable so as to bridge the outer sheath removed portion, and a metal cover having a rust-preventing function is provided on the buffer member at a position corresponding to the outer sheath removed portion. A flexible tube is provided, a fixing member is connected to the front and rear of the flexible tube, a hot melt adhesive tape is wound over the fixing member of the flexible tube, and the wound hot melt adhesive tape is wrapped around the wound hot melt adhesive tape. 1. A bent portion of a communication cable, characterized in that the flexible tube and the buffer member are fixed to the outer sheath of the communication cable by covering with a heat-shrinkable tube and heating.