JPS6026310A - Tension member for optical fiber cable - Google Patents

Abstract

PURPOSE:To eliminate the need for the protecting member of an optical fiber core by providing a spiral groove at 50-300mm. pitch on the outside circumference of an iron or steel wire subjected to plating and laying the optical fiber core therin. CONSTITUTION:A steel wire having 3.8mm. diameter is drawn with a die drawing machine to form a steel wire having the deformed sectional shape having four grooves 7 of 2.0mm. outside diameter D and 0.5mm. groove depth H. The wire is then twisted at 120mm. pitch by a wire twister and is subjected to an oil temper treatment, then to galvanizing, by which a tension member 8 is produced. An optical fiber 2 is housed in the grooves 7 and a sheath 9 consistng of an aluminum-laminated PE resin is coated on the outside circumference, thereby manufacturing an optical fiber cable 10. Flexibility and repturing force are thus improved and the handling of the fiber is made easy without requiring the protective member of the optical fiber core such as a spacer. Such fiber is easily produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tension member number for one pull of an optical fiber used in optical communications and the like.

As shown in Fig. 1, a conventional optical fiber cable has a tension member 1FJR made of steel wire or steel stranded wire in the center, and an optical fiber core 2 is housed in a spiral groove 3 on the outer periphery. It is composed of a spacer 4 and a polyurethane sheath 5 arranged around its outer edge, or it has a tension member 1 similar to the above in the center as shown in FIG.
Spacers 4 containing optical fiber cores 2 and intervening strings 6 are arranged alternately on the outside, and a sheath 5 is further placed on the outer periphery.
ft.

The characteristics of these optical fiber cables are that they have 1ffi tension member made of steel wire or steel stranded wire in the core, so the breaking strength of the cable is high, there is less risk of the optical fiber being cut, and this tension member is thin. It has advantages such as excellent flexibility because it is used as a single round wire or twisted together. However, these structures require a spacer to be placed around the tension member and a member to protect the optical fiber, which makes the structure complex and increases the cross-sectional area of the optical fiber cable as a whole. There are drawbacks.

The present invention seeks to eliminate the drawbacks of the prior art and includes a tension member 1ffi integrally constructed from a single iron wire, steel wire, or other alloy wire. That is,
The present invention consists of an iron wire, a steel wire, or a base alloy wire thereof, which has a plated surface, and has one or more spiral grooves on the outer periphery, and the depth of the groove in the longitudinal direction of the wire is an optical fiber core wire. is larger than the diameter of , and its spiral pitch is 5
011II to 300- are tension members for optical fiber cables.

The steel wire used here is usually a hard steel wire with a Cfn of 6 to 0.84, and is often plated on the surface. In addition, the number of spiral grooves is usually 2, 4, 6, 8, or 12. Spiral Pitch '15
77), which is limited to the range of 0W to 30 [ ] This is because stress concentration may occur in a portion and the optical fiber may break. 50111
A tight spiral structure with 1 to 300 layers is optimal because no light leaks and there is no risk of breakage, and stress acts evenly on each optical fiber core.

Since the present invention has the above configuration, the optical fiber pull using this tension member has a simpler structure than conventional ones, has a small cross-sectional area, has high breaking strength, and is resistant to impact from external palms. It is also strong and highly flexible.

Next, one embodiment of the present invention will be described based on the drawings.

As shown in Fig. 3, a steel wire with a wire diameter of 6.8-1/m was drawn by die drawing, and the outer diameter was 2.0, the groove depth H was Q, 5 m, i@7 F) All four steel wires with irregular cross-sections are made, and then these grooved irregular steel wires are twisted with a 12ON pitch by a twisting machine, and after oil tempering treatment, zinc Apply plating and build a tension member 8'ft:e. An optical fiber core 2'lt is housed in the spiral groove 7 of the tension member 8 as shown in FIG. 4, and its outer periphery is covered with a sheath 9 made of luminescent polyethylene resin to produce an optical fiber pull 10. .

The optical fiber cable thus obtained is superior in flexibility by 1 to 1 compared to conventional cables with the same outer diameter, has an approximately 204 improvement in breaking strength, and has a simple structure that reduces manufacturing costs. In addition to reducing the number of wires, connections, installation, maintenance, etc., are extremely easy to handle. Moreover, since the wire diameter of the cable can be reduced in accordance with these effects, the optical fiber cable using the tension member according to the present invention is very suitable for long-distance transmission equipment such as an overhead optical fiber cable.

Since the optical fiber pull tension member of the present invention has the above structure, it has excellent flexibility and breaking strength, and when used in an optical fiber cable, it does not require a member such as a spacer to protect the optical fiber core wire. Therefore, handling is extremely easy. In addition, since manufacturing is extremely simple, the cost hk width can be reduced by 6C, and the effects are very large.

[Brief explanation of drawings]

11iW and 21i1U are block diagrams of conventional optical fiber cables, FIG. 3 is a sectional view showing an embodiment of the tension member of the present invention, and FIG. 4 is a diagram of an optical fiber cable using the tension member of the present invention. FIG. 1, B,, tension member 208. Optical fiber core wire W, 7, , groove 400. Spacer j9, sheath 690. Interposed string IQ , ,, optical fiber cable patent applicant Hiroshi Kanai No. 112g Z Figure 2 O41-

Claims (1)

[Claims] Made of iron wire or steel wire or alloy wire with a plated surface, one or more spiral grooves are formed on the outer periphery, and the depth of the groove in the longitudinal direction of the wire is greater than or equal to the diameter of the optical fiber core wire. 1. A tension member for an optical fiber cable, characterized in that the tension member is provided so that the spiral pimple is 50 m+ to 5 Q O=.