JP2020071264A - Optical fiber cable and manufacturing method for optical fiber cable - Google Patents

Abstract

To provide an optical fiber cable of a small diameter having no bending directionality, and a manufacturing method therefor.SOLUTION: An optical fiber cable 1 provided herein has one tension member 3 disposed roughly at the center thereof. A plurality of optical fiber units 9 is disposed around the tension member 3. Each optical fiber unit 9 is obtained by twisting a plurality of optical fiber ribbons 9a together and forming a bundle by wrapping the ribbons with a bundling member not shown in the figure. An outer periphery of the plurality of optical fiber units 9 is wrapped with a wrapping tape 11. Further, a tear string 5 is provided as necessary, and an outer periphery of the wrapping tape 11 is covered with a sheath 13. A cable core 10 and the sheath 13 of the optical fiber cable 1 of the present invention are not adhered together. As such, shrinkage of sheath 13 is less likely to affect the optical fiber units 9 therein, minimizing an increase in loss thereby.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical fiber cable accommodating a plurality of optical fiber cores and a method for manufacturing the optical fiber cable.

  Since the amount of information transmitted in one optical fiber cable increases with the increase in the amount of information in recent years, it is desired to store the optical fibers in the optical fiber cable at a high density and increase the number of optical fiber storage cores. ing. On the other hand, various optical fiber cables have been proposed.

  As such an optical fiber cable, for example, an optical fiber cable in which a tension member is embedded in the center and a plurality of grooves are formed on the outer peripheral surface and a plurality of optical fibers are accommodated in each groove is proposed. Has been done. (For example, patent document 1).

  Further, there is proposed an optical fiber cable in which a jacket is provided on the outer circumference of a plurality of optical fiber units, and a tension member is embedded in the jacket (for example, Patent Document 2).

JP, 2014-212511, A JP, 2016-206350, A

  However, in the slot type optical fiber cable, it is difficult to make the optical fiber cable thin due to the sectional area occupied by the slots.

  Further, when the tension member is arranged in the jacket without using the slots, it is also difficult to make the optical fiber cable thin because the thickness of the jacket needs to be equal to or larger than the outer diameter of the tension member. .. Further, since the tension member is not arranged at the center of the optical fiber cable, the bending of the optical fiber cable is directional.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide an optical fiber cable having a small diameter and having no bending directionality of the optical fiber cable, and a method for manufacturing the optical fiber cable.

  In order to achieve the above-mentioned object, a first invention is to provide a cable core having a tension member and a plurality of optical fiber units arranged on the outer circumference of the tension member, and a jacket provided on the outer circumference of the cable core. The optical fiber unit is characterized in that the optical fiber unit is configured by bundling a plurality of optical fiber core wires, and the jacket and the cable core are not adhered.

  A press winding tape may be wound around the outer periphery of the cable core, and the press winding tape may be a non-woven fabric.

  A press winding tape may be wound around the outer periphery of the cable core, and the press winding tape may be made of a resin having a softening temperature higher than the softening temperature of the jacket.

  A release layer may be further provided on the outer circumference of the press-winding tape.

  According to the first aspect of the present invention, the tension member is not embedded in the jacket, but is arranged inside the cable core. Therefore, it is not necessary to unnecessarily increase the thickness of the jacket, and it is possible to reduce the diameter of the cable. Becomes

  Further, since the tension member is arranged substantially at the center of the optical fiber cable, the bending direction of the optical fiber cable is not restricted to a specific direction, and the degree of freedom in handling is high.

  On the other hand, since the tension member and the jacket are not integrated, it is not possible to suppress the shrinkage of the jacket under the use environment, and there is concern that transmission loss may increase. Is non-adhesive, the cable core is unlikely to be affected by the shrinkage of the jacket, and an increase in loss of the optical fiber can be suppressed.

  Further, by winding the non-woven fabric press-winding tape around the outer periphery of the cable core, it is possible to more reliably prevent the outer cover and the cable core from adhering to each other.

  Further, even if a resin-made press-winding tape having a softening temperature higher than the softening temperature of the jacket is wound around the outer circumference of the cable core, it is likewise possible to prevent the jacket and the cable core from adhering to each other.

  Further, if a release layer is further provided on the outer circumference of the press-winding tape, the inner optical fiber can be more reliably prevented from being affected by the shrinkage of the outer cover.

  A second aspect of the present invention is a method for manufacturing an optical fiber cable, which includes a step of twisting and disposing a plurality of optical fiber units which are configured by bundling a plurality of optical fiber core wires on the outer periphery of a tension member. A method for manufacturing an optical fiber cable, comprising: a step of winding a press-winding tape around the outer circumference of the optical fiber unit; and a step of molding an outer jacket by pipe extrusion on the outer circumference of the press-winding tape. ..

  According to the second aspect of the invention, since the jacket is not a pressure extrusion but a pipe extrusion, the cable core is not excessively pressed by the pressure of the jacket, so that the jacket and the cable core are reliably bonded. Can be prevented. Therefore, it is possible to obtain an optical fiber cable that is less susceptible to the shrinkage of the outer cover and that can suppress an increase in loss of the optical fiber.

  According to the present invention, it is possible to provide an optical fiber cable having a small diameter and a method for manufacturing the optical fiber cable, which has no bending directionality of the optical fiber cable.

Sectional drawing which shows the optical fiber cable 1. The figure which shows the optical fiber tape cable core 9a. Sectional drawing which shows the optical fiber cable 1a.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an optical fiber cable 1. The optical fiber cable 1 is mainly composed of a tension member 3, an optical fiber unit 9, a press winding 11, an outer jacket 13 and the like.

  One tension member 3 is arranged substantially at the center of the optical fiber cable 1. For the tension member 3, for example, steel wire or FRP can be applied. The outer circumference of the tension member 3 may be coated with resin.

  A plurality of optical fiber units 9 are arranged on the outer circumference of the tension member 3. In the illustrated example, four optical fiber units 9 are arranged in a twisted state. The optical fiber unit 9 is composed of a plurality of optical fiber core wires. In the illustrated example, the optical fiber unit 9 is composed of a plurality of optical fiber ribbons 9a.

  FIG. 2 is a schematic view showing the optical fiber ribbon core wire 9a. The optical fiber tape core wire 9a is configured by bonding a plurality of optical fiber element wires 17 in parallel. Adjacent optical fiber wires 17 are adhered to each other intermittently with a bonding portion 15 at a predetermined interval in the longitudinal direction of the optical fiber wires 17. The adhesive portions 15 are arranged in a zigzag pattern in the longitudinal direction of the optical fiber ribbon core wire 9a.

  In addition, in the illustrated example, an example in which the optical fiber tape 17 is composed of twelve optical fiber strands 17 is shown, but the present invention is not limited to this. Applicable. In addition, the length and the interval of the adhesive portion 15 are not limited to the illustrated example.

  The optical fiber unit 9 is configured by twisting a plurality of optical fiber ribbons 9a and winding a bundle member (not shown) to form a bundle. A plurality of the optical fiber units 9 thus obtained are further bundled and arranged on the outer circumference of the tension member 3. A cable core 10 is formed by disposing a plurality of optical fiber units 9 on the outer circumference of the tension member 3 as described above.

  In the present embodiment, the press winding 11 is arranged on the outer periphery of the cable core 10. Further, the tear cord 5 is arranged as necessary, and the outer circumference of the press winding 11 is covered with the outer cover 13. That is, the jacket 13 is provided on the outer periphery of the cable core 10 on which the press winding 11 is arranged on the outer periphery.

  The optical fiber unit 9 is only wound around a bundle member and is not inserted into a tube or the like. That is, the optical fiber units 9 are separated from each other only by the spirally wound tape-shaped bundle member. Further, the tape-shaped press winding 11 wound around the outer circumference of the optical fiber unit 9 comes into contact with the jacket 13. In addition, as the resin forming the jacket 13, for example, linear low-density polyethylene or low-density polyethylene can be applied.

  Here, the inventors have found that when the optical fiber cable 1 having the structure as shown in FIG. 1 is manufactured by the conventional method, the loss increase of each optical fiber core wire becomes large under the use environment. The inventors paid attention to the shrinkage of the jacket 13 as the cause.

  For example, a conventional slot-type optical fiber cable is covered so that the outer periphery of a slot wound with a presser winding is closely attached to the outer cover. Therefore, even if the jacket tries to contract, the contraction of the jacket is suppressed by the slot having a high elastic modulus. Therefore, it is considered that the influence of the shrinkage of the jacket transmitted to the optical fiber unit hardly occurs.

  On the other hand, in the slotless type optical fiber cable, a tension member is embedded inside the jacket. Therefore, even if the outer jacket tries to contract, the contraction of the outer jacket is suppressed by the tension member integrated with the outer jacket. Therefore, it is considered that the influence of the shrinkage of the jacket transmitted to the optical fiber unit hardly occurs.

  However, in the structure such as the optical fiber cable 1 which is the slotless type and in which the tension member 3 is not arranged inside the jacket 13, the jacket 13 shrinks in a use environment (for example, 70 ° C.), The optical fiber unit 9 (each optical fiber tape core wire 9a) is directly affected by the contraction of the jacket 13. Therefore, it is considered that a force is applied to the optical fiber ribbon 9a, which leads to an increase in loss.

  Therefore, in the optical fiber cable 1 according to the present invention, the cable core 10 and the jacket 13 are not bonded. Therefore, even if the outer cover 13 contracts, the internal optical fiber unit 9 is less likely to be affected by it, and an increase in loss can be suppressed. In order to prevent the outer jacket 13 and the inner cable core 10 from adhering to each other as described above, there is a method of forming the outer jacket 13 by pipe extrusion, for example.

  In normal pressure extrusion, the outer jacket 13 is pressed against the outer peripheral surface of the cable core 10 and pushed out, so that the inner surface of the outer jacket 13 adheres to the cable core 10. On the other hand, if the outer jacket 13 is pushed out by a pipe, the inner diameter of the outer jacket 13 is pushed out slightly larger than the outer diameter of the cable core 10. That is, it is possible to prevent the inner peripheral surface of the outer jacket 13 from being extruded smoothly without following the uneven shape of the outer peripheral surface of the cable core 10 and thus the cable core 10 and the outer jacket 13 are closely adhered and bonded. it can.

  As shown in the figure, when the press winding tape is wound around the outer circumference of the cable core 10 and the cable core 10 includes the press winding 11, the press winding 11 and the outer cover 13 are not adhered. If the press winding 11 and the jacket 13 are not adhered to each other, the influence of the shrinkage of the jacket 13 on the optical fiber unit 9 can be reduced.

  In order to ensure that the outer cover 13 and the press winding 11 are not bonded to each other as described above, there is a method of using a non-woven press winding tape as the press winding 11, for example. If the press winding 11 is a non-woven fabric, it does not melt when the outer cover 13 is extruded, and the outer cover 13 and the press winding 11 are bonded by forming the outer cover 13 by pipe extrusion as described above. Can be suppressed.

  Further, since the jacket 13 and the press winding 11 are not adhered to each other, the press winding tape may be made of a resin having a softening temperature higher than the softening temperature of the jacket 13. For example, when the press winding 11 is a PET tape or a nylon (polyamide) tape, it is possible to suppress the adhesion between the outer cover 13 and the press winding 11.

  Next, a method for manufacturing the optical fiber cable 1 will be described. First, a plurality of optical fiber ribbons 9a are twisted together, and one or more bundle members are wound around it to manufacture the optical fiber unit 9. Next, a plurality of optical fiber units 9 are twisted and arranged on the outer circumference of the tension member 3. Next, a press-winding tape is wound around the outer circumference of the plurality of optical fiber units 9. Further, the optical fiber cable 1 is manufactured by molding the outer cover 13 on the outer circumference of the press-winding tape by pipe extrusion.

  As described above, by extruding the outer cover 13 with a pipe, the outer cover 13 can be formed so that the outer cover 13 does not adhere to the internal cable core 10. Therefore, after manufacturing, even if the optical fiber cable 1 is held at the operating environment temperature of about 70 ° C. and the jacket 13 contracts, the internal cable core 10 is less susceptible to the influence and the optical fiber core wire It is possible to suppress an increase in transmission loss.

  Further, in the present embodiment, since the tension member is not embedded in the outer cover 13, it is not necessary to make the thickness of the outer cover 13 equal to or larger than the outer diameter of the tension member. Further, the thinner the jacket 13, the smaller the heat capacity of the jacket 13, and the more reliable fusion with the cable core 10 can be suppressed. For example, the thickness of the outer cover 13 is preferably 2.0 mm or less.

  As described above, according to the present embodiment, since it is the slotless type, the slot does not increase the outer diameter of the optical fiber cable. Further, since the tension member 3 is not embedded in the outer cover 13, the outer cover 13 can be made thin and the optical fiber cable can be made thin. Further, since one tension member 3 is provided in the approximate center of the optical fiber cable 1, there is no directionality of bending of the optical fiber cable 1.

  Further, even when the jacket 13 contracts at 70 ° C. which is the operating environment temperature of the optical fiber cable 1, the jacket 13 and the cable core 10 are not adhered to each other, so that the optical fiber unit 9 receives the jacket 13. The effect of shrinkage can be reduced. Therefore, it is possible to suppress an increase in transmission loss of each optical fiber core wire.

  Further, if a nonwoven fabric is used as the press winding 11, the adhesion between the outer cover 13 and the press winding 11 can be suppressed. If a resin having a high softening temperature is used for the press winding 11, the same effect can be obtained.

  A release layer 12 may be further arranged on the outer periphery of the press winding 11 as in the optical fiber cable 1a shown in FIG. The release layer 12 is made of a resin or the like that does not easily adhere to the outer cover 13. For example, the press winding 11 may be made of non-woven fabric, and the release layer 12 may be made of PET tape or nylon (polyamide) tape. By doing so, the adhesion between the release layer 12 and the outer cover 13 is suppressed, and the press winding 11 functions as a cushion, so that the shrinkage of the outer cover 13 is affected by the internal optical fiber unit 9. Can be smaller.

  An optical fiber cable with an outer jacket and a cable core bonded and an unbonded optical fiber cable were prepared, and the increase in transmission loss during the heat cycle test was evaluated. The cross-sectional structure of the optical fiber cable is generally the same as that shown in FIG.

  Twelve optical fiber strands having a diameter of 200 μm were intermittently adhered to each other to prepare intermittent optical fiber ribbons as shown in FIG. In addition, 12 optical fiber tape cores were twisted together and a 2 mm wide plastic tape was wound to form a 144-fiber optical fiber unit.

  As the tension member, a 2.0 mm glass FRP coated with low density polyethylene to have a diameter of 2.5 mm was used. Four optical fiber units having 144 cores were twisted around the tension member at a pitch of 300 mm. A water absorbent non-woven fabric was wound around the outer circumference of the twisted optical fiber unit, and an outer cover was extruded and covered thereon to form a 576-fiber optical fiber cable. The material of the outer cover was linear low-density polyethylene, and the thickness of the outer cover was 1.7 mm.

  For extruding the jacket, one of the test pieces was a normal pressure extruding piece, and the other test piece was a pipe extruding piece having a pipe shape independent of the shape of the internal cable core. The product extruded under pressure was in a state in which the outer cover was engaged and adhered to the outer surface irregularities of the non-woven fabric on the outer periphery of the cable core. On the other hand, in the pipe extruded product, the non-woven fabric and the outer cover were not adhered.

  Each optical fiber cable was prepared for 1000 m, and a heat cycle test was conducted for 3 hours at a temperature of −30 ° C. to 70 ° C., which is a general environment temperature of the optical fiber cable, and a holding time at each temperature was 6 hours. It was With respect to the transmission loss (wavelength 1550 nm) at room temperature measured in advance, an increase in loss at each temperature was confirmed. The results are shown in Table 1.

  The increase in loss in the lower part of Table 1 is indicated by “x” when it exceeds 0.15 dB / km, and by “◯” when it is 0.15 dB / km or less.

  In the example, since the pipe was extruded, the cable core and the jacket were not adhered to each other, and the influence of the shrinkage of the jacket on the cable core could be suppressed. Therefore, the loss increase during heat cycle was 0.15 dB / km or less.

  On the other hand, in the comparative example in which the pressure extrusion was performed, the outer cover and the cable core were adhered to each other, and at the time of high temperature, the outer cover that had residual processing strain was formed by winding the optical fiber core wire inside the outer cover. It is believed that it contracted, and as a result, a large increase in loss was observed.

  Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not affected by the above-described embodiments. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and naturally, these are also within the technical scope of the present invention. It is understood that it belongs.

1, 1a ... Optical fiber cable 3 Tension member 5 Tear string 9 Optical fiber unit 9a Optical fiber ribbon 10 Cable core 11 Press winding 12 ……… Release layer 13 ………… Coating 15 ………… Adhesive part 17 ………… Optical fiber strand

Claims (5)

Tension members,
A plurality of optical fiber units arranged on the outer periphery of the tension member,
A cable core having
An outer cover provided on the outer periphery of the cable core,
Equipped with,
The optical fiber unit is configured by bundling a plurality of optical fiber core wires,
An optical fiber cable, wherein the jacket and the cable core are not adhered.   The optical fiber cable according to claim 1, wherein a press winding tape is wound around the outer periphery of the cable core, and the press winding tape is a non-woven fabric.   The optical fiber cable according to claim 1, wherein a press winding tape is wound around the outer periphery of the cable core, and the press winding tape is made of a resin having a softening temperature higher than a softening temperature of the jacket.   The optical fiber cable according to claim 2 or 3, further comprising a release layer on the outer circumference of the press-winding tape. A method of manufacturing an optical fiber cable,
A step of arranging a plurality of optical fiber units, which are configured by bundling a plurality of optical fiber core wires, on the outer periphery of the tension member, and
Winding a press winding tape around the outer circumference of the plurality of optical fiber units;
A step of molding the outer cover on the outer circumference of the press-winding tape by pipe extrusion,
A method for manufacturing an optical fiber cable, comprising:

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