JP5735399B2 - Optical fiber cable and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical fiber cable formed by covering an optical fiber unit in which a plurality of optical fiber cores are bundled with a bundling member with a jacket, and a method for manufacturing the same.

  For example, in Patent Document 1, a unit is formed in which a plurality of communication lines of a communication cable are brought close to each other, and then a coarsely wound tape is spirally wound, and a unit is further attached vertically with an adhesive tape on the coarsely wound tape. A communication cable in which a tape is wound around and covered with a jacket is disclosed.

  Patent Document 2 discloses a structure in which a coarsely wound yarn or tape of a unit housed in an optical fiber cable or the like is inverted 180 degrees at a constant period and entangled at the intersection.

JP-A-3-192610 JP-A-8-180744

  However, in Patent Document 1, since a plurality of communication lines are firmly fixed by the adhesive tape, it is difficult to take out a specific communication line. Similarly, in Patent Document 2, since the intersecting portion of the coarsely wound yarn or tape that is reversed at a constant period is entangled, the intermediate branching operation is still difficult.

  Moreover, in patent document 1, since an adhesive tape is used, the handling is troublesome, and when adhesive force is too strong, it will become difficult to peel off. Moreover, in patent document 2, since the operation | work which entangles two coarsely wound yarns or a tape is required, the operation | work is complicated and troublesome.

  Accordingly, the present invention provides an optical fiber cable that can easily bundle a plurality of optical fiber cores with a bundling member and can easily take out a specific optical fiber core from an optical fiber unit during an intermediate branching operation, and its manufacture. It aims to provide a method.

  According to a first aspect of the present invention, there is provided an optical fiber cable in which an optical fiber unit in which a plurality of optical fiber cores are bundled with at least two binding members and covered with a jacket through a presser winding tape. The binding member is spirally wound around the circumferential surface of the core bundle of the optical fiber bundles, and the other binding members are also spirally wound along the longitudinal direction. Alternatively, by being vertically attached along the longitudinal direction of the core wire bundle, the binding members are bonded to each other at the intersection where the binding members intersect, and the melting point of the binding member is set to Bmp. When the outer resin temperature at the time of extrusion molding covering the optical fiber unit with the outer jacket is Pt, and the melting point of the press-wound tape is Rmp, Bmp <Pt <Rmp, and It is characterized in that the area occupied by the fiber unit is not more than 60% more than 30% void area within the cable.

  The second invention is an optical fiber cable according to the first invention, characterized in that the intersection where the binding members intersect is heat-sealed by heat at the time of covering.

  3rd invention is a manufacturing method of the 1st optical fiber cable, Comprising: The said binding member cross | intersects with the heat | fever by the jacket resin temperature when the said optical fiber unit is coat | covered with the said jacket by extrusion molding It is characterized in that the intersections are bonded by heat fusion.

  According to the optical fiber cable of the present invention, the jacket resin temperature Pt at the time of extrusion molding for covering the optical fiber unit with the jacket is higher than the melting point Bmp of the binding member and lower than the melting point Rmp of the press-wound tape (Bmp <Pt <Rmp) so that the intersection of the bundling member is thermally fused and bonded (joined) with heat during extrusion of the outer jacket, and the bundling member is heat-sealed with the press-wound tape. Can be prevented.

  Further, according to the optical fiber cable of the present invention, since the occupied area of the optical fiber unit is 30% or more and 60% or less of the gap area in the cable, the bundling member is connected to the inner wall surface of the jacket and the outer wall via the presser winding tape. It becomes easy to touch during coating, and the intersection of the bundling members is heat-sealed by the heat during coating, and the optical fiber core wire also loses transmission loss in the gap of the cable even when contracted due to temperature change of the optical fiber cable. The transmission loss fluctuation can be suppressed without the occurrence of a bend that causes deterioration of the transmission. With these effects, according to the present invention, it is possible to easily bundle a plurality of optical fiber cores with a bundling member, and to easily take out a specific optical fiber core from the optical fiber unit during intermediate branching operations. it can.

FIG. 1 is a cross-sectional view of the optical fiber cable of this embodiment. FIG. 2A is a side view showing an example of the optical fiber unit, and FIG. 2B is an enlarged view of a main part in which the optical fiber core wire is omitted at a portion where the binding members intersect. 3 is an enlarged cross-sectional view of the optical fiber unit shown in FIG. FIG. 4 is an enlarged cross-sectional view of the optical fiber core wire. FIG. 5 is an enlarged cross-sectional view of the binding member used in FIG. FIG. 6 is a cross-sectional view showing an example in which a plurality of pieces of flat yarns are used as a binding member. FIG. 7 is a manufacturing process diagram of an optical fiber cable. FIG. 8 is a diagram showing a bundling member winding step in the optical fiber cable manufacturing process in which a plurality of core wire bundles are covered with the same jacket.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  As shown in FIG. 1, the optical fiber cable 1 of the present embodiment has a structure in which an optical fiber unit 2 is covered with a jacket 4 via a presser winding tape 3.

  As shown in FIGS. 2 and 3, the optical fiber unit 2 is formed by bundling a plurality of optical fiber cores 5 with at least two binding members 6 (6A, 6B). The structure is a single bundle so as not to be separated. 1 to 3, the number of optical fiber cores 5 is not the same, but in FIGS. 2 and 3, the number has been changed to make the structure easy to understand. The number of the core wires 5 is the same.

  For example, as shown in FIG. 4, the optical fiber core wire 5 is a quartz glass fiber 7 provided in the center, and a colored optical fiber formed by covering the quartz glass fiber 7 with an ultraviolet curable resin and a colored layer. It consists of a strand 8 and a colored reinforcing layer 9.

  In this example, the optical fiber core having the structure shown in FIG. 4 is taken as an example, but a plurality of colored optical fibers and colored optical fibers are arranged and collectively covered with an ultraviolet curable resin, It is assumed that an optical fiber core wire in which optical fiber strands adjacent to each other are intermittently fixed is also included in the optical fiber core wire of the present invention.

  As shown in FIG. 5, the binding member 6 includes a core portion 6a made of a high melting point material having a high melting point provided at the center, and a lower melting point than the high melting point material provided to cover the core portion 6a. It has a double structure having a jacket portion 6b made of a melting point material. The binding member 6 exhibits adhesiveness when heated, but does not exhibit adhesiveness when not heated. Further, the binding member 6 has a string shape with a circular cross-sectional shape in the example of FIG. Of course, the shape of the binding member 6 is not limited to the circular shape in FIG. The bundling member 6 may be used singly, or a plurality of bundling members as shown in FIGS. 6A and 6B may be used as the bundling member 6. FIG. 6A is an example in which a plurality of bundling members 6 are combined so as to be appropriately flat yarns, and FIG. 6B is an example in which a plurality of bundling members 6 are aligned to form flat yarns. .

  The difference in melting point between the high melting point material and the low melting point material is preferably at least about 20 ° C. or more. Specifically, the melting point of the high melting point material is preferably about 160 ° C., and the melting point of the low melting point material is specifically preferably about 120 ° C. to 130 ° C. In addition, the low melting point material used for the jacket portion 6b does not adhere to the optical fiber core 5 even when heated and melts, or has a low adhesive force even if it is bonded. It is required that the layer (colored reinforcing layer 9) is not deteriorated.

  Examples of the high melting point material and the low melting point material include a high melting point resin such as polyamide and PET (polyethylene terephthalate), or a polypropylene fiber, a polyamide fiber (registered trademark, such as nylon and aramid), and a polyester fiber (such as PET fiber). Thermoplastic resins capable of reversibly repeating softening and solidification by heating and cooling of high melting point fibers or high melting point tapes or films such as PET and polypropylene, such as EVA (ethylene vinyl acetate copolymer), EEA (ethylene So-called hot melt adhesives that have a low melting point, such as ethyl acrylate copolymer), or can be reversibly softened and solidified by heating and cooling based on thermoplastic resins and rubbers. The one covered with can be used. In addition, LDPE (low density polyethylene), LLDPE (linear low density polyethylene), HDPE (high density polyethylene), polypropylene, and copolymers thereof can also be used. The difference in melting point is set to a high melting point and a low melting point depending on the composition of the material.

  In FIG. 2, two bundling members 6 are used, and are wound around the optical fiber core wire 5 bundled together in a spiral manner at a predetermined pitch along the longitudinal direction with the winding directions opposite to each other. Yes. For example, one binding member 6A is wound along the longitudinal direction so as to be spirally wound around the core bundle 5A of several optical fiber cores 5 bundled in a circular shape in a clockwise direction. It is rolled up.

  On the other hand, the other binding member 6B is wound along the longitudinal direction so as to be spirally wound in a counterclockwise direction opposite to the winding direction of the one binding member 6A. By winding the two binding members 6A and 6B around the core wire bundle 5A with the winding directions of the two binding members 6A and 6B opposite to each other, as shown in FIG. 2, the intersection portion where the binding members 6A and 6B intersect with each other is the optical fiber core wire 5 Are formed in the longitudinal direction.

  In the two bundling members 6, one bundling member 6 A is spirally wound along the longitudinal direction, and the other bundling member 6 B is disposed along the longitudinal direction of the core bundle of the optical fiber core wire 5. It may be attached vertically in a straight line.

  The winding pitch P of the binding members 6A and 6B is preferably set to 80 mm to 200 mm, for example. When the winding pitch P of the binding members 6A and 6B is less than 80 mm, the distance between the intersections of the binding members 6A and 6B is too short. There is a possibility that the optical fiber is bent when the optical fiber core wire is sandwiched, and the transmission loss fluctuates. The core contrast operation is an operation for specifying an arbitrary optical fiber core. Light of a specific wavelength is incident from the end of the optical line, etc., and the optical fiber core is detected by an optical fiber contrast machine at an intermediate branch point. It is an operation to detect light by inserting a line. On the other hand, if the winding pitch P of the binding members 6A and 6B exceeds 200 mm, the bundling property (group) of the optical fiber core wire 5 deteriorates due to the intersection distance between the binding members 6A and 6B being too wide. Visibility is inferior, workability is poor, and in the worst case, there is a possibility that different optical fiber core wires 5 may be cut by mistake. Therefore, the winding pitch P of the binding members 6A and 6B is preferably in the above range.

  The binding members 6A and 6B belong to any of the plurality of optical fiber units when a plurality of the optical fiber units 2 in which a plurality of optical fiber cores 5 are bundled are accommodated in the same cable. Colored to identify what is. For example, in an optical fiber cable in which three optical fiber units 2 are housed in the same cable, the color of the binding member 6 of one optical fiber unit 2 is yellow, and the color of the binding member 6 of another optical fiber unit 2 These three optical fiber units 2 are identified with blue being the color of the remaining binding members 6 and green.

  The intersection T of the two binding members 6A and 6B is heat-sealed by the heat at the time of covering the optical fiber unit 2 with the outer cover 4, and the binding members 6A and 6B are bonded to each other. The adhesive strength is not strong, and it is desirable that the strength does not affect the damage to the optical fiber core 5 and its transmission characteristics when the optical fiber core 5 is hooked. By doing this, when taking out a specific optical fiber core wire 5 out of a plurality at the time of the intermediate branching work, it is possible to remove the bonding portion by hand without cutting the binding members 6A and 6B and widen the take-out portion. It becomes possible. The two bundling members 6A and 6B can be bonded again by applying heat from a heater after the optical fiber core wire 5 is taken out by an intermediate branching operation.

  The press-wound tape 3 is bonded to the jacket 4 by the optical fiber unit 2 so that the optical fiber core wire 5 can be easily taken out from the cable when it is led out from the end portion of the optical fiber cable 1 or during an intermediate branching operation. It is provided not to. The presser winding tape 3 is vertically attached or horizontally wound in the longitudinal direction of the cable so as to wrap the optical fiber unit 2 from the outside.

  The jacket 4 covers the optical fiber unit 2 so as to be accommodated therein. The outer cover 4 is provided with tension members 9 and 9 for restricting the cable bending direction on both sides of the optical fiber unit 2 on the line passing through the center of the optical fiber cable 1. In addition, the outer jacket 4 is formed on a line passing through the center of the optical fiber unit 1 and perpendicular to a line connecting the two strength members 9 and 9, with the optical fiber unit 2 being sandwiched between both sides thereof. 15 and 15 are provided. The outer cover 4 is formed by extruding the optical fiber unit 2 with the press-wound tape 3 interposed therebetween, thereby covering the optical fiber unit 2 so as to be accommodated therein.

  In the optical fiber cable 1 of this embodiment, the melting point of the bundling member 6 is Bmp, the jacket resin temperature during extrusion molding covering the optical fiber unit 2 with the jacket 4 is Pt, and the melting point of the press-wound tape 3 is Rmp. In this case, the relationship Bmp <Pt <Rmp is satisfied, and the occupation area of the optical fiber unit 2 is 30% to 60% of the gap area in the cable. The air gap area in the cable is defined as an area obtained by subtracting the cross-sectional area of the press-wound tape 3 from the cross-sectional area of the internal space 10 formed at the center of the jacket 4 in a cross section perpendicular to the longitudinal direction of the optical fiber cable 1. .

  By satisfying the above conditions, when the outer cover 4 is extruded, the intersection portion of the binding member 6 comes into contact with the outer cover 4 via the presser winding tape 3, and the heat of the binding member 6 is heated by the heat of the outer cover. The intersecting point T is heat-sealed and bonded, and the press-wound tape 3 is not joined to the outer cover 4 without being heat-sealed.

  When the above conditions are not satisfied, for example, when Bmp> Pt, the bundling member 6 is not fused by the heat at the time of covering. Further, when Pt> Rmp, the presser winding tape 3 is melted and the outer cover 4 and the presser winding tape 3 adhere to each other, so that separation becomes difficult at the time of discarding the cable, and the recyclability is impaired. The condition of Bmp <Pt <Rmp is required in order to bond the intersection point T of the bundling member 6 with heat at the time of coating the outer cover, and to prevent the presser wound tape 3 from being melted.

  Further, if the occupied area of the optical fiber unit 2 is less than 30% of the gap area in the cable, the occupied area of the optical fiber unit 2 is too small with respect to the internal space 10, and the intersection T of the bundling member 6 is pressed against the press tape. 3, it becomes difficult to contact the inner wall surface of the jacket 4, and the bundling member 6 is not heat-sealed by the heat at the time of coating the jacket. On the contrary, if the occupied area of the optical fiber unit 2 exceeds 60% of the gap area in the cable, the ratio occupied by the optical fiber unit 2 is so large that the optical fiber core wire 5 can meander when the cable contracts with respect to the temperature change. Becomes smaller, the optical fiber core wire 5 is bent to a small diameter, and the transmission characteristics deteriorate. A transmission loss by joining the intersection T of the bundling member 6 by heat-sealing with the heat at the time of covering, and allowing the optical fiber core wire 5 to meander in the inner space 10 within a range in which the transmission loss due to bending does not occur. In order to suppress the fluctuation, the condition that the occupied area of the optical fiber unit 2 is 30% or more and 60% or less of the gap area in the cable is necessary.

The reason why the area occupied by the optical fiber unit 2 is preferably 30% to 60% of the gap area in the cable is based on the following experimental results. A prototype cable was created under the following conditions. The prototype cable has one optical fiber unit, the optical fiber unit is bundled with a bundling member (melting point Bmp is 125 ° C.), and press-wound tape (0.25 mm thick polyester tape, melting point Rmp is 258). ), And a tensile body (φ0.7mm steel wire) is mounted on the jacket (linear low density polyethylene, melting point Pt is 124 ° C), and the outer shell resin temperature Pt is set to 155 ° C and extruded. An optical fiber cable having a diameter (diameter) of 7.5 mm was manufactured. Note that the gap area in the cable was constant, and the ratio of the optical fiber unit to this was adjusted by increasing or decreasing the number of optical fiber cores. The results are shown in Table 1.

  At the time of evaluation, regarding the adhesiveness of the intersection of the binding members on the optical fiber unit, if not bonded, each of the optical fiber core wires will be scattered at the time of intermediate branching and terminal branching at the time of aerial installation, and workability will be reduced. There is concern that it will get worse. For this reason, 10 m of the internal optical fiber unit was taken out from the end of the prototype cable, and the case where 90% or more of the intersections were adhered was marked as ◯, and the case where it was less than 90% was marked as x.

  Regarding cable transmission characteristics, if the proportion of the optical fiber unit in the air gap is too large, the clearance that can meander in the range where the optical fiber core wire does not cause transmission loss due to bending when the cable contracts with respect to temperature changes is small, and the optical fiber There is a concern that the core wire is bent to a small diameter and transmission characteristics deteriorate. Therefore, winding the optical fiber cable around a drum and placing it in a room at −30 ° C. for 12 hours, measuring the transmission loss, and subsequently placing it in a room at + 70 ° C. for 12 hours and measuring the transmission loss are repeated 3 cycles. (Heat cycle), the case where the transmission loss fluctuation was less than 0.15 dB / km from the initial stage was marked as ◯, and the case where it was 0.15 dB / km or more was marked as x.

  As a result, it was confirmed that when the occupied area of the optical fiber unit is 30% or more and 60% or less of the gap area in the cable, the adhesiveness at the intersection of the binding members is good and the cable transmission characteristics are not impaired. .

  Next, the manufacturing method of the optical fiber cable of this embodiment is demonstrated. To manufacture the optical fiber cable 1 described above, as shown in FIG. 7, a bundle of optical fibers 5A of a plurality of optical fiber cores 5 is run in the direction indicated by the arrow X in the figure. As the optical fiber core 5, an optical fiber core having the structure shown in FIG. 4 was used.

  Then, two binding members 6A and 6B are wound around the core wire bundle 5A. The binding members 6A and 6B pass along the longitudinal direction of the core wire bundle 5A by passing through the center holes 12 of the ring-shaped caps 11A and 11B provided in the middle of the traveling path of the core wire bundle 5A. The center hole 12 is formed as a circular hole slightly larger than the diameter of the core wire bundle 5A. One binding member 6A is rotated clockwise or counterclockwise around the core bundle 5A as shown by an arrow M1 in FIG. 7, and is passed through the center hole 12 of the base 11A, thereby the core bundle 5A. Wound in a spiral. The other binding member 6B is rotated about the core bundle 5A in the opposite direction to the binding member 6A as shown by an arrow M2 in FIG. 7 and passes through the center hole 12 of the base 11B, and the core bundle 5A. Wound in a spiral. The two binding members 6A and 6B are fed out from the respective paper tubes 16A and 16B and supplied to the respective caps 11A and 11B.

  Next, the presser winding tape 3 is wound around the peripheral surface of the core wire bundle 5A and vertically attached to the core wire bundle 5A bundled by the two binding members 6A and 6B. Then, the outer cover 4 is extruded together with the two tensile strength members 9 and 9 and the tear strings 15 and 15 by the extrusion molding machine 14, and the bundled core wire bundle 5A is covered to manufacture the optical fiber cable 1.

  When the jacket 4 is pushed out, the intersecting point of the two binding members 6A and 6B is bonded by heat due to the temperature of the jacket resin temperature at the time of covering. For this reason, the core wire bundle 5 </ b> A is prevented from being loosened by the binding members 6 </ b> A and 6 </ b> B being unwound within the cable covered with the jacket 4.

  In the optical fiber cable manufacturing method of the present embodiment, the crossing point T where the bundling members 6A and 6B intersect is heat-sealed and bonded by heat due to the temperature of the jacket resin when the jacket 4 is coated by extrusion molding. In addition, it is not necessary to pre-heat the intersection point T in the previous step of coating with the jacket 4, and the manufacturing cost can be reduced because it can be performed simultaneously with the jacket. And according to the optical fiber cable 1 manufactured in this way, in connection work after aerial installation, workability is achieved by being unitized and bound from the viewpoint of handling extra length to a closure or the like. Will improve dramatically.

  Further, the optical fiber cable 1 manufactured as described above is led out from the cable terminal portion to take out the specific optical fiber core wire 5, and the outer cover 4 is peeled off from the middle of the cable so that the specific optical fiber is peeled off. When the intermediate branching operation for taking out the fiber core 5 is performed, the specific optical fiber core 5 can be taken out without the core wire bundle 5A being separated in any case.

  In the example of FIG. 7, the optical fiber cable 1 is manufactured by covering one core wire bundle 5 </ b> A with the jacket 4, but as shown in FIG. 8, a plurality of (four in this example) are provided. When the optical fiber cable 1 is manufactured by covering the core bundle 5A with the same jacket 4, a plurality of core bundles 5A are arranged in parallel, and the core members 11A, 11B are used as the binding members 6A, Wrap 6B.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical fiber cable in which an optical fiber unit in which a plurality of optical fiber cores are bundled with a bundling member is covered with a jacket.

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Optical fiber unit 3 Press winding tape 4 Outer jacket 5 Optical fiber core wire 6 (6A, 6B) Bundling member 10 Internal space

Claims (3)

In an optical fiber cable in which an optical fiber unit in which a plurality of optical fiber cores are bundled with at least two binding members and covered with a jacket through a presser winding tape,
At least one bundling member is spirally wound along the longitudinal direction around the circumferential surface of the bundle of optical fiber cores, and the other bundling members are also spiraled along the longitudinal direction. Or are vertically attached along the longitudinal direction of the bundle of core wires so that the binding members are bonded to each other at the intersection of the binding members,
Bmp <Pt <Rmp, where Bmp is the melting point of the bundling member, Pt is the temperature of the outer sheath resin during extrusion molding that covers the optical fiber unit with the outer sheath, and Rmp is the melting point of the press-wound tape. And an occupation area of the optical fiber unit is not less than 30% and not more than 60% of the gap area in the cable. The optical fiber cable according to claim 1,
An intersection at which the binding members intersect is heat-sealed by heat at the time of covering. It is a manufacturing method of the optical fiber cable according to claim 1,
Manufacturing an optical fiber cable, wherein the optical fiber unit is bonded by heat-sealing the intersection where the binding members intersect with the heat of the outer cover resin temperature when the optical fiber unit is covered with the outer cover by extrusion molding. Method.

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