JP4431071B2 - Optical cable and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical cable for optical communication such as that used for optical wiring in a home or premises, and a method for manufacturing the same.

  Optical cables used for in-home optical wiring or the like generally have a configuration in which a tension member is placed in order to reinforce the tensile strength of an optical fiber, and is collectively covered with a cable covering or the like. Further, this type of optical cable needs to have its cable covering removed when processing a terminal for connecting an optical connector or the like. In order to facilitate the removal of the cable covering, it is known to provide a slit for cutting in the longitudinal direction of the cable covering. However, if the groove for tearing is provided from the surface of the cable cover to the inside, when multiple optical cables are laid, the tearing groove portions may be caught with each other, causing damage to the optical cable. is there. Further, when the cable sheath is torn, there is a fear that the internal optical fiber is tensioned or damaged.

In order to improve this, a structure in which a groove for tearing is provided on the inner surface side of the cable sheath has been proposed (see, for example, Patent Document 1 and Patent Document 2). FIG. 8 (A) and FIG. 8 (B) is a diagram showing a configuration example of a disclosure of the optical cable in Patent Document 1 above. Optical cable 1a shown in FIG. 8 (A), covering one tension member 2 of the optical fiber cord 3 arranged in parallel to the tension member 2, the outer peripheral portion of the optical fiber cord 3 and tension member 2 In this structure, the outer peripheral portion is covered with a sheath 4 (cable covering) so as to be almost elliptical.

The tension member 2 is for maintaining the strength of the optical cable, and has a structure in which the outer periphery of the steel wire 2a is covered with a sheath 2b. The optical fiber cord 3 has a structure in which the outer peripheral portion of the optical fiber core wire 6 is covered with a resin layer 7 and the outer peripheral portion is covered with a sheath 8. On the inner peripheral surface of the sheath 4 covering the tension member 2 and the optical fiber cord 3, slits 9a and 9b having a triangular cross section are formed. In addition, the optical cable 1b shown in FIG. 8B has a plurality of optical fiber cords 3 arranged around the tension member 2 and covered with a sheath 5, and the outer periphery of the optical cable 1b is substantially circular. It is the structure covered with the sheath 4 so that it may become. Similarly, tearing grooves 9 a and 9 b having a triangular cross section are formed at symmetrical positions on the inner peripheral surface of the sheath 4.

A slit is made by a nipper or the like in the portion where the grooves 9a and 9b for tearing are formed, and the sheath 4 is torn up and down. The portions where the grooves 9a and 9b for tearing are formed have a small cross-sectional area and can be easily torn. In addition, the surface of the sheath 4 is not uneven due to the grooves, and when laying a large number of optical fiber cables 1 at the same time, there is no risk of causing damage to the optical cable. It is said that the cord 3 can be prevented from being damaged.
JP 2004-264473 A Japanese Patent Laid-Open No. 2004-77888

Optical cable shown in FIG. 8 (A) and FIG. 8 (B) cross-section features a optical fiber cord and a tension member of a circular, a structure covered with a sheath comprising an outer cable covering. For this reason, a gap is formed between the tension member and the optical fiber cord or adjacent to the contact portion between the plurality of optical fiber cords, and the cord elements that are not in close contact with each other are arranged in the optical cable. When an optical cable having such a structure is bent, the cable elements move relative to each other within the sheath, and the optical cable is likely to be bent. When an optical cable with a bending rod is laid in a house or premises, there is a problem that if the optical cable is inserted into a piping for wiring, the insertion resistance is large, and the existing optical cable and the entangled wiring are not easy to work. Further, in the optical cable subjected to the sheath of the elliptical shape as shown in FIG. 8 (A), the directivity is generated in the bending direction. For this reason, there is a problem that the bending direction is limited by the wiring at the corners, or a small local bending occurs to deteriorate the transmission characteristics.

Therefore, a structure in which a tension member is concentrically arranged in an optical fiber cord, a cable sheath is concentrically provided in the optical fiber cord, and a tearing groove is provided on the inner surface of the cable sheath has been studied. In order to make the cable covering have removability, it is necessary that the cable covering provided on the outer periphery of the cord covering does not adhere to the cord covering but has peelability. However, when the cable covering is slippery with respect to the cord covering, there is still a problem that bending wrinkles are generated, and the cord covering and the cable covering are locally displaced, and damage and kinks are likely to occur due to stress concentration.
The present invention has been made in view of the above-described circumstances, and in an optical cable having a cable tearing groove in the cable sheath, there is no directionality to bending, and an optical cable that hardly causes bending wrinkles and kinks and its manufacture It is an object to provide a method.

The optical cable and the manufacturing method thereof according to the present invention are optical cables in which at least two layers of a cord coating and a cable coating are concentrically formed on a single-core optical fiber coated with a protective coating. A tensile strength fiber is arranged on the outer periphery of the central single-core optical fiber core, and a cord coating is formed so as not to adhere to the protective coating of the single-core optical fiber core wire. The cable coating is formed by extrusion coating so as to be in the state. At the same time, a notch for tearing the cable sheath is formed at least at two locations on the inner surface side of the cable sheath, and the gap portion of the notch is filled with a protrusion integrally provided on the outer side of the cord sheath. Further, the gap portion of the notch, the vertical served by a resin tape to the outer surface of the code covering may be filled with projections by the edges were left tension to the side of the resin tape.

The single-core optical cable according to the present invention is provided with a notch on the inner surface side of the cable sheath, so that there is no risk of causing damage to the optical cable as in the prior art, and the cable sheath is cut without damaging the internal optical fiber cord. Can be torn. Further , since the cable covering is not adhered to the cord covering but can be brought into a close contact state , the optical cable can suppress the occurrence of kinks due to bending wrinkles or bending.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a basic configuration of an optical cable targeted by the present invention, FIGS. 2 and 3 are reference examples of the present invention, and FIGS. 4 and 5 are diagrams illustrating an embodiment of the present invention . In the figure, 11, 11a to 11e are optical cables, 12 are tensile fibers, 13 is an optical fiber cord, 14 is a cable coating, 15 is a boundary surface, 16 is an optical fiber, 17 is a protective coating, 18 is a cord coating, 19a and 19b Is a notch , 20 is a filler, 21 is a tensile strength fiber, 22 is a resin tape, 22a is a tape edge, and 23 is a protrusion.

  As shown in FIG. 1, in the optical cable 11, the tensile strength fiber 12 is arranged on the outer periphery of the optical fiber core wire in which the optical fiber 16 for transmitting light is covered with the protective coating 17, and the protective coating 17 is not adhered to the outer side thereof. The optical fiber cord 13 is concentrically provided with a cord coating 18. On the outer periphery of the single optical fiber cord 13, a circular cable sheath 14 is provided in close contact with the cord sheath 18 so as not to slip, although it does not adhere to the cord sheath 18. That is, the boundary surface 15 between the cord sheath 18 and the cable sheath 14 is arranged concentrically in a state where they do not adhere to each other but do not easily slip due to close contact or frictional force. Further, notches (also referred to as grooves) 19a and 19b for tearing the cable covering are provided in the cable covering 14 from the inner surface side toward the outer surface side.

  The optical fiber 16 includes various glass fibers such as a single mode fiber and a multimode fiber having a standard outer diameter of 125 μm, a plastic clad glass fiber made of a glass core and a plastic clad, and a plastic fiber made of a plastic made of a core and a clad. Can be used. For example, the outer periphery of these optical fibers is protected by a protective coating 17 made of an inner coating such as an ultraviolet curable resin or a silicone resin and an outer coating such as nylon or flame retardant polyolefin. The protective coating 17 is formed with an outer diameter of 0.5 mm to 0.9 mm, for example.

  The tensile strength fiber 12 is an optical cable or optical fiber cord that has a protective function to prevent a certain amount of force from being exerted when a tension is applied to the connecting portion when the terminal portion is connected to an optical connector or the like. It is. As the tensile strength fiber 12, high-strength aramid fiber or the like is used, and for example, Kevlar (DuPont registered trademark), Twaron (AKZO registered trademark), Technora (Teijin registered trademark), or the like is used.

  A cord coating 18 is formed from the outside of the tensile strength fiber 12 so as to surround the optical fiber core wire. For example, polyvinyl chloride, flame retardant polyolefin, or the like is used for the cord coating 18 and is formed by an extrusion molding machine so that the outer diameter is 1.1 mm to 3.0 mm. Since the cord coating 18 is formed on the optical fiber coating via the tensile strength fiber 12, the cord coating 18 is unlikely to adhere to the protective coating 17, and the optical fiber core wire is not subjected to stress due to the expansion / contraction of the cord coating 18. . However, when the cord coating 18 is extruded, the tensile strength fiber 12 is not softened at the extrusion temperature of the cord coating 18, but is indexed by the cord coating 18 in a molten state, causing fluctuations in characteristics, or being taken into the cord coating. In order to avoid this, it is desirable to attach a release material such as talc to the tensile strength fiber 12.

  In the state where the cord coating 18 is provided, an optical connector or the like is connected to the terminal, and the single-core optical fiber cord 13 capable of optical wiring inside or between devices is obtained. If the cord coating 18 is thickened, transmission loss increases due to low temperature shrinkage, and the removability and bendability of the coating material decrease. If the coating thickness is increased, good characteristics are not obtained. For this reason, in order to lay in a home or premises, or to be installed by being inserted into an optical pipe, an optical cable having a cable coating 14 provided on the outer periphery of the optical fiber cord 13 is used. The cable coating 14 is made of polyvinyl chloride, flame retardant polyolefin, or the like, similar to the cord coating 18, and is formed by an extrusion molding machine so that the outer diameter is about 5.0 mm, for example.

  The cable coating 14 is provided so as not to be bonded to the cord coating 18 so that the cable coating 14 can be easily removed (a method for non-bonding the cord coating 18 and the cable coating 14 will be described later). However, when the boundary surface 15 between the cable sheath 14 and the cord sheath 18 is slippery and the optical fiber cord 13 has a small pulling force with respect to the cable sheath 14, the buckling diameter becomes large and kinks are likely to occur. Is also likely to occur. For this reason, in the present invention, the cable sheath 14 is formed so as not to adhere to the cord sheath 18 but to be slippery. In order to make the cable sheath 14 and the cord sheath 18 difficult to slip, it can be realized by increasing the frictional force of the cable sheath 14 in close contact with the outer periphery of the cord sheath 18 as described below. .

In the present invention, as described with reference to FIG. 8 , notches 19 a and 19 b from the inner surface side to the outer surface side are provided on the inner side of the cable sheath 14 at at least two positions facing each other. The notches 19a and 19b are formed in, for example, a triangular cross section with the inner surface side of the cable sheath 14 having a bottom of 0.8 mm width and a height of 1.0 mm. When removing the cable covering 14, an inner optical fiber cord 13 can be taken out by making an incision at the end of the cable covering 14 with a cutter knife or a nipper and tearing the cable covering 14 starting from the notched portion. In this case, in the portion where the notches 19a and 19b are formed, the thickness from the surface of the cable sheath 14 is small, so that it is easy to cut and tear, without damaging the internal optical fiber cord. Can be easily torn.

Notch 19a, as 19b, there is shown an example of a triangular, may be formed so that the thickness from the surface than the total thickness of the cable coating 14 decreases, the notch 19a, the void volume of 19b larger There is no need to do. Further, in the optical cable 11a shown as a reference example of the present invention in FIG. 2, it has a configuration for filling a filler 20 made of a material which is not bonded to the cable jacket 14 to the gap portion of the notch 19a, 19b. By filling the gap 20 in the notches 19 a and 19 b with the filler 20, the gap in the notches is filled to compensate for the decrease in the contact area with the cord coating 18 . However, it is not sufficient to increase the frictional force between the cord sheath 18 and the cable sheath 14 and reduce the occurrence of slippage .

In the optical cable 11b of the reference example shown in FIG. 3, tensile strength fibers 21 are vertically arranged in the gap portions of the notches 19a and 19b or in the vicinity thereof, and the gap portions of the notches 19a and 19b are filled with the tensile strength fibers 21. It is. The tensile fiber 21 used here is the same as the tensile fiber 12 such as an aramid fiber interposed between the protective coating 17 and the cord coating 18 of the optical fiber core . Notch 19a, the gap portion of 19b are met in tensile strength fiber 21.

The optical cable 11c according to the present invention shown in FIG. 4 causes the tape edge 22a to be joined to protrude sideways when the resin tape 22 is vertically attached to the outer surface of the cord coating 18, and fills the gap portions of the notches 19a and 19b. It is what I did. The resin tape 22 is also useful for providing a cord coating 18 and a cable coating 14 described later and a non-adhesive function. The notches 19a, a gap portion of 19b by filling at the edge portion 22a of the resin tape 22, increases the frictional force between the code covering 18 and cable jacket 14, it is possible to reduce slippage.

The optical cable 11d according to the present invention shown in FIG. 5 has a triangular protrusion 23 integrally formed at at least two symmetrical positions so as to protrude from the side surface of the cord coating 18 when the cord coating 18 is formed by an extruder. Provided by molding. When the cable cover 14 is formed by an extruder so as not to adhere to the outside of the cord cover 18, notches 19 a and 19 b are formed inside the cable cover 14 by the protrusions 23. Notch 19a, the gap portion of 19b of this time, a state filled by projections 23, increasing the frictional force between the code covering 18 and cable jacket 14, it is possible to reduce slippage.

The optical cables 11c and 11d according to the present invention formed as described above are prepared, for example, for laying a house with a length of about several meters, and the terminal portion is introduced into a connection box or an optical device to connect an optical connector. Therefore, the cable covering is removed. To remove the cable sheath, a notch in a symmetrical position is cut with a nipper or the like to make a cut of about 10 mm. In order to easily identify the position of the notch, an identification line indicating the notch position may be provided on the surface of the cable covering. After making a cut in the cable jacket, the cable jacket can be easily torn along the notch by pulling the cable jacket to both sides .

  Tear the cable sheath, take out the inner optical fiber cord by a predetermined length (for example, 20 cm to 50 cm), remove the cord sheath at its end, expose the optical fiber core wire and connect it to the optical connector; The tensile strength fiber is secured to the housing of the optical connector. An optical cable with an optical connector can be provided by attaching a boot so that the optical fiber cord is not bent suddenly when the optical fiber cord is introduced into the optical connector or when the cable sheath is removed.

6 and 7 are diagrams showing various manufacturing methods of the above-described optical cable. In the figure, 10 is an optical fiber core, 25 and 26 are extrusion molding machines, 27 is a release material coating device, 28 is a winding device, 29 is a die, 30 is a nipple, and 31 is a blade member. Other reference numerals is omitted by using the same reference numerals as used in FIGS.

6 (A) is a diagram showing an example of producing the basic form of optical cable described above, first, the outer periphery of the optical fiber 10 of single-core and attach longitudinal tensile strength fibers 12 of aramid fibers, extruded on the outside A cord coating 18 is formed by a molding machine 25 to obtain a single-core optical fiber cord 13. Although the tensile strength fiber 12 itself does not soften at the coating temperature of the cord coating 18, the tensile strength fiber 12 is prevented from being indexed by the cord coating 18 in a molten state and causing fluctuations in characteristics or being taken into the cord coating. Therefore, it is desirable to apply a release material such as talc to the tensile strength fiber 12.

  A cable coating 14 is formed on the outer circumference of the single-core optical fiber cord 13 by an extrusion molding machine 26, so that the single-core optical cable 11 having a circular cross section is formed. As described with reference to FIG. 1, the cable covering 14 is not bonded to the cord covering 18 but needs to be provided so as not to slide on each other. As one method for preventing the cable coating 14 from adhering to the cord coating 18, it can be realized by forming the cable coating 14 at a temperature below the temperature at which the surface of the cord coating 18 is deformed.

  However, the processing temperature of the cable coating 14 is not that a material lower than the processing temperature of the cord coating 18 is used, but the temperature at which the cable coating 14 contacts the surface of the cord coating 18. That is, even if the processing temperature of the cable covering 14 and the cord covering 18 is the same, the temperature of the cable covering 14 in the softened state should be low when covering the outer periphery of the cord covering 18. For example, if the cable covering 14 is formed at a temperature lower by about 20 ° C. than the deformation temperature of the cord covering 18, the cable covering 14 and the cord covering 18 are not bonded. For this purpose, it is also useful to form the cable covering 14 by previously setting the cable covering 18 in a low temperature state.

The cable coating 14 does not adhere to the cord coating 18 but needs to be formed in a close contact state by extrusion coating so as not to slip. Moreover, to provide a notch on the inner surface of the cable jacket 14, it is necessary to form in debiting the form as shown in FIG. 7 (A) to be described later. For this reason, there may be a case where a sufficiently close contact state cannot be obtained. In the manufacture of the optical cable of the reference example shown in FIGS. 2 and 3 , the filler 20 such as the tensile fiber filling the gap portion of the notch Supplied vertically on the side.

FIG. 6 (B) are allowed to adhere to the release material on the surface of the cord tube 18 is a diagram illustrating a method for avoiding the adhesion between the cable cover 14. As the release material, talc and silicone oil that remain stably even at the temperature at the time of forming the cable coating 14 are preferable. Before the cable coating 14 is formed by extrusion on the outer periphery of the optical fiber cord 13, talc or silicone oil is applied by passing through a release material coating device 27 and is adhered by wiping with a nonwoven fabric. Further, the vertical served with filler 20, such as tensile strength fiber to the side of the code covering 18, filling the gap portion of the notch of the cable jacket 14 is similar to that of FIG. 6 (A).

In the optical cable according to the present invention shown in FIG. 5 as well, the cable coating 14 is formed at a temperature at which the surface of the cord coating 18 is deformed or lower, and a release material is attached to the surface of the cord coating 18. A method of forming the cable sheath 14 is used. However, in the case of the optical cable according to the present invention shown in FIG. 5, since the ridge filling the gap portion of the notch of the cable cover 14 is integrally formed on the cord cover 18, there is no need to separately add a filler. Can be omitted.

FIG. 6 (C), the surface of the cord tube 18 keep covered with resin tape 22 is a diagram showing a manufacturing method of the optical cable according to the present invention for forming a cable jacket 14. As described with reference to FIG. 4, this method is also used to vertically attach the resin tape 22 to the outer surface of the cord coating 18, and the joining edge portion fills the gap portion of the notch in the cable coating. As the resin tape 22, for example, a tape made of a resin having a high thermal deformation temperature such as polyethylene terephthalate (PET) or polyamide is used. The resin tape 22 is wound by the winding device 28 or vertically attached so as to cover the entire circumference of the optical fiber cord 13. Note that the configuration and to To meet the gap portion of the notch in FIG. 4, and vertical served with two resin tape, to the edge portion of the junction to protrude laterally.

Figure 7 (A), (B) is a diagram showing details of the head portion of the extruder 26. In the resin extrusion port portion, the end surfaces of the die 29 and the nipple 30 are made to substantially coincide with each other so that the cable covering 14 is formed in a drawn-out form. The degree of adhesion of the optical fiber cord 13 to the outer periphery can be adjusted by changing the suction pressure between the cable covering 14 and the optical fiber cord 13 in a softened state. A notch can be provided on the inner surface of the cable covering 14 by providing the blade member 31 at least at the symmetrical position on the outer surface of the nipple 30 .

In order to evaluate the present invention, a standard single-mode optical fiber coated with a protective coating having an outer diameter of 0.9 mm was used as the optical fiber core. An optical fiber cord was obtained by arranging Kevlar fiber on the outer periphery of the optical fiber core and forming a cord coating with an outer diameter of 2.0 mm with flame-retardant polyethylene. An optical cable was obtained by forming a cable coating having an outer diameter of 5.0 mm on the outer periphery of the optical fiber cord using the same flame-retardant polyethylene as the cord coating. An optical cable was obtained by forming a cable coating having an outer diameter of 5.0 mm on the outer periphery of the optical fiber cord using the same flame-retardant polyethylene as the cord coating. Further, by the method shown in FIG. 7, to form a triangular notch (height 1.0 mm, width 0.3 mm).

The above two types of optical cables were subjected to a kink test according to JIS-C6851. In the case of the optical cable in which the gap portion of the notch remains hollow , kinks occurred in all of the 10 samples before the inner diameter of the optical cable reached 10 cm. On the other hand, in the case of the optical cable in which the gap portion of the notch is filled , no kink occurred even when the inner peripheral diameter of the optical cable reached 8 cm.

  The reason why such a difference occurs is that if there is a gap portion between the cord sheath and the cable sheath that does not exert force on each other, the gap portion is deformed, and the cord sheath and the cable sheath are This seems to be because it tends to be a starting point for slipping.

It is a figure for demonstrating the basic composition of the optical cable made into the object of this invention. It is a figure which shows the reference example of the optical cable by this invention. It is a figure which shows the other reference example of the optical cable by this invention. It is a figure explaining an example of the optical cable by this invention. It is a figure explaining the other example of the optical cable by this invention. It is a figure explaining the manufacturing method of the optical cable by this invention. It is a figure explaining the structure of the head part of the extrusion molding machine explaining the manufacturing method of the optical cable by this invention. It is a figure explaining the prior art.

DESCRIPTION OF SYMBOLS 11, 11a-11e ... Optical cable, 12 ... Tensile fiber, 13 ... Optical fiber cord, 14 ... Cable coating, 15 ... Interface, 16 ... Optical fiber, 17 ... Protective coating, 18 ... Cord coating, 19a, 19b ... Notch , 20 ... Filler, 21 ... Tensile fiber, 22 ... Resin tape, 22a ... Tape edge, 23 ... Projection, 25, 26 ... Extrusion molding machine, 27 ... Release agent coating device, 28 ... Winding device, 29 ... Die , 30 ... nipple, 31 ... blade-like member.

Claims (5)

An optical cable in which at least two layers of a cord coating and a cable coating are concentrically formed on a single-core optical fiber having a protective coating,
Although a tensile strength fiber is arranged on the outer periphery of the single-core optical fiber, a cord coating is provided so as not to adhere to a protective coating of the single-core optical fiber, and the cord coating is not adhered to the outside of the cord coating. cable jacket is provided in contact state, said cable coating of the inner surface side of the at least two locations in the notch for tearing the cable jacket is formed, a gap portion of the notch is provided integrally on the outside of the cord cover protrusion An optical cable characterized by being filled with An optical cable in which at least two layers of a cord coating and a cable coating are concentrically formed on a single-core optical fiber having a protective coating,
A tensile strength fiber is arranged on the outer periphery of the single-core optical fiber, a cord coating is provided so as not to adhere to a protective coating of the single-core optical fiber, and a resin tape is vertically attached to the outer surface of the cord coating The edge of the resin tape is protruded to the side, and the cable coating is provided in a close contact state without being bonded to the resin tape on the outside of the resin tape, and the cable coating is for tearing at least two places on the inner surface side of the cable coating. A notch is formed, and a gap portion of the notch is filled with a ridge formed by an edge protruding to the side of the resin tape . A method of manufacturing an optical cable in which at least two layers of a cord coating and a cable coating are concentrically formed on a single-core optical fiber core wire provided with a protective coating,
Although a tensile strength fiber is arranged on the outer periphery of the single-core optical fiber, a cord coating is formed so as not to adhere to a protective coating of the single-core optical fiber, and the cord coating is not adhered to the outside of the cord coating. A cable coating is formed by extrusion coating so as to be in a close contact state, and at the same time, notches for tearing the cable coating are formed in at least two locations on the inner surface side of the cable coating, and a gap portion of the notch is formed outside the cord coating. A method for manufacturing an optical cable, characterized in that the optical cable is filled with protrusions provided integrally therewith. A method of manufacturing an optical cable in which at least two layers of a cord coating and a cable coating are concentrically formed on a single-core optical fiber core coated with a protective coating,
  A tensile strength fiber is arranged on the outer periphery of the single-core optical fiber, a cord coating is formed so as not to adhere to a protective coating of the single-core optical fiber, and a resin tape is vertically attached to the outer surface of the cord coating The edge of the resin tape is projected to the side, and the cable coating is formed by extrusion coating so that the resin tape is not adhered to the outer side of the resin tape but is in a close contact state, and at the same time, at least on the inner surface side of the cable coating 2. A method of manufacturing an optical cable, comprising forming notches for cable covering tearing at two locations, and filling a gap portion of the notches with ridges formed by edges protruding to the side of the resin tape. 5. The method of manufacturing an optical cable according to claim 3 , wherein an extrusion coating temperature of the cable coating is set to be equal to or lower than a temperature at which a surface of the cord coating is deformed.

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