JPH02245713A - Optical cable - Google Patents

Abstract

PURPOSE:To obtain the optical cable which has no possibility of cutting of coated optical fibers and is light in weight and small in diameter by inserting and fixing a tension member constituted by adhering high tensile fiber bundles to a cord shape with a synthetic resin into the selected spiral grooves of a core material. CONSTITUTION:The cord-shaped core material 10 consisting of a tough synthetic resin having a core wire 2 consisting of a steel wire or fiber reinforced plastic in the axial central part and having the plural spiral grooves 15-1 to 15-4 in the outer peripheral part is provided. Coated optical fibers 1 are loosely inserted respectively into selected two lengths of the spiral grooves 15-1, 15-3 and a tension member 50 constituted by adhering the high tensile fiber bundle to the cord shape by the synthetic resin is inserted into the other spiral grooves 15-2, 15-4 and is sealed by fixing. Fastening tapes 3 are lap wound on the outer peripheral surfaces of the fiber material 10 to seal the coated optical fibers 1 and the tension member 50, respectively. The tension member hardly elongates even if tensile force is applied on the optical cable and, therefore, the tension force is hardly applied on the coated optical fibers and the possibility of cutting is eliminated.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of the optical cable, there is no fear that the optical fiber core wire will be cut by external force, the transmission loss of the optical fiber will not fluctuate due to lateral pressure, and it is small in diameter and lightweight. A cord-shaped core material made of tough synthetic resin that has a core wire made of steel wire or fiber reinforced plastic at the axial center and multiple spiral grooves on the outer periphery, with the aim of providing optical cables that are easy to handle. , an optical fiber core wire loosely inserted and arranged in the selected spiral groove, and a high tensile strength fiber bundle that is inserted and fixed in another spiral groove other than the one in which the optical fiber core wire is loosely inserted. A cable jacket consisting of a tension member bonded in a cord shape with resin, a fastening tape wrapped around the outer circumferential surface of the core material, and a cable jacket made of an elastic synthetic resin that covers the outer circumference of the fastening tape. shall be.

[Industrial application field]

The present invention relates to the structure of an optical cable.

Optical cables, which are made by bundling multiple optical fibers into a desired shape and protecting the outer periphery with a cable sheath, are designed to ensure that the transmission characteristics will not deteriorate due to lateral pressure or bending of the optical fibers, and that they are resistant to tensile forces, etc. Therefore, it is required that the optical fibers not only do not break, but also be lightweight and easy to handle.

[Conventional technology]

FIG. 6 is a sectional view of a conventional optical cable, and FIG. 7 is a side view of the core material.

In Fig. 6, the outer circumference of the optical fiber is made of nylon.
It is an optical fiber coated with a fiber jacket made of synthetic resin such as polyethylene or polycarbonate, and its outer diameter is 0.5 mm to 0.9 mm.

2 is a tensile strength body made of steel wire, FRP (fiber reinforced plastic), or the like.

10 has a core wire 2 at the axial center and a plurality of wires (4 in the figure) at the outer periphery.
The core material is made of a tough synthetic resin (for example, polyethylene) and has a spiral groove 15 in the shape of a cord, as illustrated in FIG. 7, and has an outer diameter of about 5 mm.

The lead length of the spiral groove 15 of the core material 10 is determined by the allowable bending radius of the optical cable, but is usually 100 to 50.
0 wm.

5 is a tension member made by aligning a large number of high tensile strength fibers (for example, aromatic polyamide fibers) and then twisting them into a wire shape, the outer diameter of which is 0.5 to 0.9 mm. It is.

A desired number (four in the figure) of spiral grooves 1 are formed on the outer periphery of the core material 10.
5 are provided, and a coated optical fiber 1 is inserted into each spiral groove 15.

Then, two spiral grooves 1 adjacent to every other core material 10 are formed.
5, the optical fiber core 1 is loosely inserted into the L, and the tension members 5 are loosely inserted into the other two spiral grooves 15, and then a tightening tape 3 made of nylon tape or the like is wrapped overlappingly.
The optical fiber core 1 and the tension member 5 are placed in the spiral groove 15.
It is contained.

Furthermore, the outer layer of the fastening tape 3 is made of polyethylene.

The optical cable is constructed by providing a cable jacket 4 made of a strong and elastic synthetic resin such as vinyl chloride and having a thickness of 0.8 to 1 mm.

As described above, the optical fiber core 1 is housed in the spiral groove of the resilient core material 10, and the outside of the core material 10 is covered with the cable jacket 4 made of a strong and resilient synthetic resin.

Therefore, even if a pressing force is partially applied to the optical cable from the radial direction, damage to the optical fiber coated wire 1 or strong lateral pressure from being applied to the optical fiber coated wire 1 is prevented.

Further, since the tension member 5 is inserted into the other two spiral grooves 15, the cable is strong against tensile force and elongation is suppressed.

On the other hand, core material 10. Optical fiber core wire l, tensi town member 5. Since both the cable sheath 4 and the cable sheath 4 are flexible and each material is lighter than metal, the optical cable described above has the advantage of being lightweight and having appropriate flexibility, and being easy to wind up on a drum or the like. .

[Problem to be solved by the invention]

However, the tension member 5 used in the above-mentioned conventional optical cable is made of a large number of high tensile strength fibers and then twisted into a wire shape so that it can be easily inserted into the spiral groove 15.

Therefore, in addition to the tension member 5 being twisted, there is also slack between the strands of the individual high tensile strength fibers.
The length of each strand of the high tensile strength fiber is longer than the length of the optical fiber core 1 .

Furthermore, since the tension member 5 is loosely inserted into the spiral groove 15, there is a gap between the tension member 5 and the inner wall of the spiral m15.

Due to the above, when a tensile force is applied to the optical cable, the tension member 5 stretches a large amount even with a relatively weak force. That is, the function as a tensile strength member is reduced, and the core material 1o of the optical cable is elongated. Therefore, a tensile force is applied to the optical fiber, which may cause it to break.

The present invention was created in view of these points, and there is no fear that the optical fiber core wire will be cut due to external force, and the transmission loss of the optical fiber is changed due to lateral pressure. The object of the present invention is to provide a bright optical cable by providing a cable jacket 4 made of synthetic resin that is elastic and does not move, is small in diameter, lightweight, and has good handling properties. shall constitute a cable.

[Means to solve the problem]

In order to achieve the above object, the present invention has a core wire 2 made of steel wire or fiber reinforced plastic at the axial center, and a plurality of spiral grooves 15-1.15- at the outer periphery, as shown in FIG. 2
．． A cord-shaped core material 10 made of a tough synthetic resin having a hardness of 15-3 and 15-4 is provided.

Then, the optical fiber cores 1 are loosely inserted into the two selected spiral grooves 15-1 and 15-3.

On the other hand, the other spiral groove 15 into which the optical fiber core l is not loosely inserted
-2. A tension member 50 constructed by bonding a high tensile strength fiber bundle in a cord shape with a synthetic resin is inserted into the 15-4 and fixedly sealed.

Then, the fastening tape 3 is wrapped around the outer peripheral surface of the core material 10, and the optical fiber core 1 is placed in the spiral groove 15-1, 15-3, and the tension member is placed in the spiral groove 15-2, 25-4. Contain 5° respectively.

[Effect]

The tension member 5° of the optical cable of the present invention is constructed by bonding a high tensile strength fiber bundle formed by aligning individual strands into a cord shape with synthetic resin. The tension member 5o is then inserted into the spiral groove and is tightly and firmly attached to the inner wall of the spiral groove, so that it is integrated with the core material 10.

Therefore, not only is there no gap between the outer circumferential surface of the tension member 50 and the inner wall of the helical groove, but also the length of each strand of the high tensile strength fiber is the length of the helical groove (the length of the optical fiber core wire). Since it is approximately equal to , the amount of elongation of the tension member 5o against a constant external force is small, that is, the function as a tensile strength member is improved.

Therefore, even if a tensile force is applied to the optical cable, the tension member 50 hardly stretches, the elongation of the core material by 1° is small, and almost no tensile force is applied to the optical fiber. Therefore, there is no fear that the optical fiber will be cut.

Note that the tension member 50 of the present invention replaces the conventional tension member 5 made of twisted high tensile strength fibers.
This does not affect the flexibility, weight reduction, and diameter reduction of optical cables.

〔Example〕

The present invention will be specifically described below with reference to the drawings. Note that the same reference numerals indicate the same objects throughout the figures.

Fig. 1 is a diagram showing the principle of the present invention, (a) is a partially cutaway side view, (b) is a sectional view, and Fig. 2 is a diagram of an embodiment of the present invention.
a) is a cross-sectional view, Cb) is a perspective view of the tension member, and FIG. 3 is a view of another embodiment of the present invention, (a) is a cross-sectional view,
) is a perspective view of the tension member.

4 is a block diagram of a tension member manufacturing apparatus according to the present invention, and FIG. 5 is a block diagram of an optical cable manufacturing apparatus according to the present invention.

In FIG. 2, reference numeral 10 denotes a cord-shaped core material made of a tough synthetic resin such as polyethylene, and a core wire 2 of a tensile strength material such as steel wire or fiber-reinforced plastic is attached to the axis.
is buried.

Further, on the outer circumference of the core material 10, there are two U-shaped spiral grooves 15-1 and 15-3 into which the optical fiber core 1 is inserted, and two spiral grooves into which the tension member 50A is inserted and fixed. 15
-2.15-4 is provided.

The spiral groove 15-2, 15-4 has a circular cross section with a portion cut away. Therefore, elastic pressing fins 16 are formed on both sides of the band-shaped opening of the spiral groove.

In addition, the above-mentioned spiral groove is 15-1.15-2.15-3
．． They are formed in the order of 15 to 4, and their leads are equal. Further, the outer diameter of the core material 10 is approximately 5++ m.

50A, as shown in detail in FIG. 2(b), a large number of high tensile strength fibers (for example, aromatic polyamide fibers) 20 are arranged into a bundle, and then a synthetic resin (epoxy, In addition to impregnating and adhering thermoplastic resins such as urethane, polyester, nylon, and vinyl chloride,
This is a tension member in which a coating layer is provided around the outer periphery of a high tensile strength fiber bundle to form a flexible cord.

The cross-sectional shape of the tension member 50 is a partially cut-off circular shape that can be inserted into the spiral grooves 15-2 and 15-4.

Moreover, the tension member 50A has a spiral groove 15-2.1.
5-4 and is pressed by the pressing fins 16, thereby being fixed in the spiral groove. Note that if the pressing fin 16 is heated to fuse the pressing fin 16 and the resin of the tension member 50A, the tension member 50A can be more securely fixed in the spiral groove.

A fastening tape 3 made of nylon tape or the like is wrapped around the outer peripheral surface of the core material 10 to seal the optical fiber core 1 within the spiral groove.

Furthermore, the outer layer of the fastening tape 3 is made of polyethylene.

The optical cable is constructed by providing a cable jacket 4 made of a strong and elastic synthetic resin such as vinyl chloride and having a thickness of 0.8 to lam.

As mentioned above, the tension member 50A, which is constructed by bonding high tensile strength fiber bundles made of aligned individual strands in a cord shape with synthetic resin, is inserted into the spiral groove, and is firmly attached to the inner wall of the spiral groove. Thus, it is integrated with the core material 10.

Therefore, since the length of each strand of the high tensile strength fiber is approximately equal to the length of the spiral groove 15 (length of the optical fiber core), the function as a tensile strength body is improved. Therefore, even if a tensile force is applied to the optical cable, the tension member 50A hardly stretches, the elongation of the core material 1O is small, and almost no tensile force is applied to the optical fiber. That is, there is no risk of the optical fiber core being cut.

Furthermore, since the optical cable is configured as described above, even if a pressing force is applied to a portion of the optical cable in the radial direction, the optical fiber core 1 may be damaged or strong lateral pressure may be applied to the optical fiber core 1. There is no risk of it being granted.

The constituent materials of the optical cables mentioned above are all lightweight and
It is also flexible. Therefore, it is easy to promote flexibility, weight reduction, and diameter reduction of optical cables.

Alternatively, the tension member 50B may have a shape as shown in FIG. 3. In FIG. 15-1゜15-
3, and two spiral grooves 15-2 and 15-4 each having a half-moon cross section into which the tension member 50 is inserted and fixed.

As shown in detail in FIG. 3Cb), the tension member 50B is made by aligning a large number of high tensile strength fibers (for example, aromatic polyamide fibers) 20 into a half-moon cross section, and then inserting a synthetic resin between the high tensile strength fibers 20. At the same time, a coating layer is provided around the outer periphery of the high tensile strength fiber bundle to form a flexible cord.

In this case, when the spiral groove does not have a pressing fin, the tension member 50B having a half-moon cross section is inserted into the spiral groove 15-2 and 15-4 having a half-moon cross section, and is heated to coat the core material 10. Since the layers and the synthetic resin of the tension member 50 are fused together, the tension member 50B is fixed within the spiral grooves 15-2 and 15-4 of the core material 10.

The tension members as shown in FIGS. 2 and 3 described above can be easily manufactured by using a manufacturing apparatus as shown in FIG. 4.

22 is a bobbin around which the high tensile strength fiber 20 is wound.

A desired number of bobbins 22 are arranged in a rotatable manner, and the high tensile strength fibers 20 supplied from each bobbin 22 are collected by a cylindrical wire concentrator 23 to form a bundle with a desired cross-sectional shape, and crosshead injection is performed. It will be installed on machine 24.

Using a crosshead injection machine 24, a desired synthetic resin (thermoplastic resin such as epoxy, urethane, polyester, nylon, vinyl chloride, etc.) 21 is impregnated and bonded between the high tensile strength fibers 20, and the outer periphery of the high tensile strength fiber bundle is A coating layer is provided on the surface.

Then, the synthetic resin 2 is drawn into the cooling tank 25.
1 is cooled and hardened. Then, the tension member 50 pulled out from the cooling tank 25 is wound onto the winding bobbin 26.

Furthermore, in order to attach the optical fiber core 1 and the tension member 50 to the core material 10, a manufacturing apparatus as shown in FIG. 5 may be used.

In FIG. 5, 31 indicates a spiral groove 15-1 having a desired shape.
, 15-2.15-3.15-4 is wound around the core material 10.

30, a fixed plate 331, a rotating disk 34. This is a twisting device in which a focusing ring 36° insertion die 37 is arranged in this order.

The fixing plate 33 is disk-shaped and has a through hole in the center into which the core material 10 is drawn, and a desired number of bobbins 26 around which the tension member 50 is wound and the optical fiber core 1 are wound on the disk surface. A desired number of bobbins 28 are arranged as desired.

The rotating disk 34 has a disk shape that is rotationally driven, and has a core material 1 at the center.
The tension member 50 or the optical fiber core 1 is disposed coaxially with the fixing plate 33, and the tension member 50 or the optical fiber core 1 is disposed on the disk surface at a position corresponding to the bobbin 26, 28 of the fixing plate 33. Holes for loose insertion and extraction are provided, and idle boobies IJ-35 having guide grooves on the circumferential surface are rotatably mounted corresponding to each hole.

The rotating disk 34 is rotated at a desired rotational speed by means not shown (for example, a belt is applied to the circumferential surface and the belt is driven by a motor).

Then, a focusing ring 36 for drawing the optical fiber core 1 and the tension member 50 onto the outer circumferential surface of the core material 10 is arranged coaxially with the rotating disk 34, and the optical fiber core 1 is arranged behind the focusing ring 36. Insertion dies 37 are arranged in the spiral grooves to respectively insert the core material 10 into the corresponding spiral grooves.

In order to manufacture an optical cable using the above-mentioned twisting device 30, the core material lO is fed out from the drum 31, and the guide 3
2 into the fixing plate 330 through hole, and then the core material 1
0 into the through hole of the rotating disk 34.

and focusing ring 36. While passing through the insertion die 37,
Optical fiber core 1. Then, the tension member 50 is inserted into a desired spiral groove, and the tension member 50 is fixed to the core material 10 by, for example, heating.

Then, the fastening tape 3 is wound in layers through the hollow hole of the tapered wrapper 40, and the sleeve 4
Shape through step 1.

Next, it is introduced into a crosshead injection machine 43 via a guide 42. A desired synthetic resin layer is formed using a crosshead injection machine 43.
The synthetic resin is attached to the outer peripheral surface of the fastening tape 3 and drawn into the cooling bath 44 to cool and harden the synthetic resin. The optical cable 100 according to the present invention is then wound up on a drum 46 via a guide 45 pulled out from the cooling tank 44, thereby obtaining a completed optical cable 100 according to the present invention.

〔Effect of the invention〕

As explained above, the present invention is an optical cable in which a tension member constructed by bonding high tensile strength fiber bundles in a cord shape with synthetic resin is inserted and fixed into a selected spiral groove of a core material, and the optical cable is subjected to lateral pressure. Even if a tensile force is applied to the optical cable, there is no risk that the transmission characteristics of the optical fiber will deteriorate, and even if a tensile force is applied to the optical cable, there is no risk of the optical fiber core wire being cut.

Furthermore, it has excellent practical effects, such as being lightweight, small in diameter, and easy to handle as an optical cable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the →→→ principle of the present invention, (a) is a partially cutaway side view, (b) is a cross-sectional view, and Fig. 2 is a diagram of an embodiment of the present invention. 3 is a diagram of another embodiment of the present invention, (a) is a sectional view, b) is a perspective view of the tension member, and FIG. 4 is a perspective view of the tension member. FIG. 5 is a block diagram of a tension member manufacturing apparatus, FIG. 5 is a block diagram of an optical cable manufacturing apparatus of the present invention, FIG. 6 is a sectional view of a conventional example, and FIG. 7 is a side view of a core material. In the figure, 1 is an optical fiber core, 2 is a core wire, 3 is a fastening tape, 4 is a cable jacket, 5.50, 50^, 50B is a tension member, 10 is a core material, 15, 15-1.15 -2.15-3.15-4 is a spiral groove, 16 is a pressing fin, 20 is a high tensile strength fiber, 21 is a synthetic resin, 22.26.28 is a bobbin, 24.43 is a crosshead injection machine, 30 is a A twisting device, 31. 46 is a drum, 33 is a fixed plate, 34 is a rotating disk, 36 is a focusing ring, 37 is an insertion die, and 40 is a tapered wrapper.

Claims (1)

[Claims] A cord-shaped core material (2) made of a tough synthetic resin having a core wire (2) made of steel wire or fiber-reinforced plastic in the axial center and a plurality of spiral grooves (15) in the outer periphery. 10), optical fiber coated wires (1) loosely inserted and arranged in the selected spiral grooves (15-1, 15-3), and other coated optical fibers other than the optical fiber coated wires (1) loosely inserted into the spiral grooves (15-1, 15-3). A tension member (50), which is inserted and fixed into the spiral groove (15-2, 15-4) and is constructed by bonding high tensile strength fiber bundles in a cord shape with synthetic resin, and the core material (10). An optical cable comprising: a fastening tape (3) wrapped around an outer peripheral surface; and a cable sheath (4) made of an elastic synthetic resin and covering the outer periphery of the fastening tape (3).