JP2012234079A - Optical drop cable, and lead-in structure of optical drop cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical drop cable ensuring good install workability even when installed in a long span, suppressing slip from an anchor tool after installation, and suppressing occurrence of curling habit during installation.SOLUTION: An optical drop cable 1 is configured mainly in that a support wire part 15 and a core wire part 17 are connected by a connection part 11. The support wire part 15 which is connected with the core wire part 17 by the connection part 11 is configured in that a support wire 7 is covered with a sheath 9. That is, an optical fiber core wire 3, a tension member 5 and the support wire 7 are collectively covered with the sheath 9, via the connection part 11. The coefficient of static friction of the sheath resin is specified in the range of 0.20 or more by JIS K 7125. The tensile strength of the support wire 7 is appropriately set according to a tension imparted to the support wire 7 (the optical drop cable 1) during or after installation, so that fracture is prevented. In addition, in the present invention, the yield point strength of the support wire 7 is specified in the range of 725 to 1880 MPa and more desirably of 905 to 1430 MPa.

Description

  The present invention relates to a self-supporting optical drop cable excellent in laying workability and an optical drop cable dropping structure.

  Conventionally, in order to lay an optical cable or the like for an apartment house or the like, the optical cable is branched by a closure formed in the vicinity of a utility pole provided outdoors, and the optical cable is pulled down and installed in each room or the like.

  In view of the allowable tension of the support wire and the landscape after installation, such an optical drop cable has been laid so as to avoid installation of a long diameter of about 30 m or more and to make the installation length of the optical drop cable alone as short as possible. It was. Specifically, it is not drawn directly from the connection box to the subscriber's house, but is drawn along the hanging line or trunk cable stretched between the cable struts and brought to the point closest to the optical subscriber's house. Has been.

  Examples of such a self-supporting type optical drop cable include, for example, at least one optical fiber core or optical fiber unit, a sheath covering the optical fiber core or optical fiber unit, and the optical fiber embedded in the sheath. There is an optical fiber cable including at least two tension members arranged along a core wire or an optical fiber unit (Patent Document 1).

  In addition, as a method of laying such a self-supporting optical drop cable, the self-supporting cable can pass almost inwardly through the extending power pole and twisted in the longitudinal direction. A self-supporting cable that is installed in a twisted state by attaching a cable threading tool having a passage and extending the cable while applying a twist corresponding to the twisting of the threading tool when passing through the cable threading tool. There is a laying method (Patent Document 2).

JP 2005-257752 A Japanese Patent Laid-Open No. 04-101606

  In recent years, the spread of FTTH services has increased, and the number of suburban subscribers has increased. In order to perform optical wiring at low cost even in areas with low housing density, the extension of trunk cables and the number of connection boxes have been reduced. As a result, there have been cases in which an optical drop cable is laid between several cable posts and pulled down to an optical subscriber's house. At this time, since there is no appropriate suspension line or trunk cable, it has been observed that an optical drop cable is laid alone.

  Usually, the optical drop cable is fixed to the cable post by an outdoor wire retainer. For this fixing, it is necessary to manually pull the support line of the optical drop cable and wind the support line around the tensioning device while adjusting the slackness.

  At this time, in order to lay the optical drop cable so as not to damage the landscape, it is necessary to suppress the slackness to about 1% between the spans. For this reason, as the span increases, the tension that is pulled for adjusting the sag increases. Specifically, it is about 9 kg at a span of 30 m, about 12 kg at 40 m, and about 14 kg at 50 m, and is relatively large as a pulling force with one hand. For this reason, in high-altitude work with a low degree of freedom, it is difficult to wind the optical drop cable with high tension while winding it around the tensioning tool, and there is a risk that the looseness will increase. In this case, it is necessary to remove the wound support wire and perform the work of winding again.

  However, if the support wire is too hard, the winding operation becomes difficult. In particular, when performing not only the first winding operation but also the second winding operation, the bending wrinkles attached to the first winding operation become large, which may hinder the second and subsequent winding operations.

  On the other hand, if the support wire is too soft, or if the coefficient of friction of the resin coated on the support wire is too low, after the installation of the optical drop cable laid between the long diameters, the tension increases due to, for example, strong wind or temperature change, and the support There is a risk of slipping off or pulling out of the wire. If the support wire is too soft, the bundle or drum rotation speed may be overrun with respect to the feeding speed when the bundled or drum-wound optical drop cable is fed out by hand. In this case, the cable bends to cause bending wrinkles, which not only deteriorates workability but also damages the landscape after laying.

  The present invention has been made in view of such problems, and ensures good laying workability even when laid between the long diameters, suppresses slipping off from the tensioning device after laying, and generates bending bends during laying. An object of the present invention is to provide an optical drop cable or the like with reduced noise.

  In order to achieve the above-mentioned object, a first invention is a self-supporting optical drop cable, which is a support wire, an optical fiber core wire, a tension member, the support wire, the optical fiber core wire, and the tension. The support wire is a steel wire having a yield strength of 725 MPa to 1880 MPa, and the resin in the previous period has a static friction coefficient of 0.20 or more according to JIS K 7125. This is an optical drop cable.

  It is desirable that the yield strength of the support wire is further 905 MPa to 1430 MPa, and that the resin in the previous period has a static friction coefficient of 0.20 or more according to JIS K 7125. The surface of the support wire is preferably galvanized.

  According to the invention of the first aspect, since the support wire has an appropriate yield point strength and an appropriate static friction coefficient of the coating resin, it can be easily wound around a tensioning device while applying high tension to the support wire. is there. In addition, the repetitive winding workability is also good, the amount of slipping through the retainer after laying is small, and the frequency of occurrence of bending wrinkles during laying is low. In addition, corrosion resistance can be improved by galvanizing the surface of a support wire.

  A second invention uses the optical drop cable according to the first invention, and in the draw-down portion, the resin covering the support wire and the resin covering the optical fiber and the tension member are separated, and the support wire However, the optical drop cable dropping structure is supported by being wound around and supported in at least two directions with respect to the retainer.

  According to the second aspect of the present invention, it is possible to obtain an optical drop cable dropping structure in which the cable does not fall off even during long-term laying, and the support wire can be easily fixed to the retainer.

  According to the present invention, it is possible to provide an optical drop cable or the like that ensures good laying workability even when laid between long diameters, suppresses slipping off from a retainer after laying, and suppresses generation of bending wrinkles during laying. be able to.

Sectional drawing which shows the optical drop cable 1. FIG. The figure which shows the drawing-down structure of an optical drop cable. FIG. 3 is an enlarged view of the vicinity of the retainer, where (a) is an enlarged view of part A of FIG. 2 and (b) is an enlarged view of part B of FIG. The figure which shows the state which the support line part produced the clearance gap with respect to the retainer. The figure which shows the state which vibrates with respect to the optical drop cable with which both ends were fastened with the retainer. (A) is a figure which shows the state which pulls out the optical drop cable 1 from a bobbin, (b) is a figure which shows the curl of the optical drop cable 1. FIG. The figure which shows the state which draws out the optical drop cable 1 from a bobbin using the gold wheel 37. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a self-supporting optical drop cable 1. The optical drop cable 1 is mainly configured by connecting a support wire portion 15 and a core wire portion 17 by a connecting portion 11.

  The core portion 17 is configured by covering the optical fiber core wire 3 and the tension member 5 together with a sheath 9.

  The optical fiber core wire 3 is provided at a substantially central portion of the core wire portion 17. The optical fiber core 3 has a coating resin made of, for example, an ultraviolet curable resin or a thermosetting resin on the outer periphery of the glass optical fiber. The coating resin includes a primary coating layer and a secondary coating layer applied on the primary coating layer, and an extremely thin colored layer for identification is formed as necessary.

  The optical fiber core 3 is, for example, a glass optical fiber having an outer diameter of 125 μm, a primary coating layer as a buffer layer, a secondary coating layer that protects the primary coating layer, and a few μm formed as necessary. For example, having an outer diameter of about 250 μm.

  On both sides of the optical fiber core wire 3, tension members 5 are provided. The center of the optical fiber core 3 and the center of each tension member 5 are located on substantially the same plane. As a material of the tension member 5, for example, an aramid fiber bundle or a fiber reinforced plastic (FRP) using an aramid fiber as a reinforcing fiber can be applied.

  V-shaped notches 13 are formed on the outer periphery of the sheath 9 positioned above and below the optical fiber core 3 as necessary. The notch 13 is for tearing the sheath 9 and easily taking out the optical fiber core wire 3 inside. The shape of the notch 13 is not limited to the illustrated example.

  As a material of the sheath 9, for example, EVA (ethylene vinyl acetate copolymer), EEA (ethylene / ethyl acrylate copolymer), PE (polyethylene), PP (polypropylene), or the like can be used. Carbon black can also be added to these resins for flame retardants and weather resistance.

  Note that the outer diameter of the cross section of the core wire portion 17 may be, for example, approximately 3.1 mm × 2 mm of the major axis × minor axis.

  The support wire portion 15 connected to the core wire portion 17 and the connection portion 11 is configured by covering the support wire 7 with a sheath 9. That is, the optical fiber core wire 3, the tension member 5, and the support wire 7 are collectively covered with the sheath 9 via the connecting portion 11. Further, the tension member 5 and the support wire 7 are arranged in parallel with the optical fiber core wire 3 over the entire length in the cable longitudinal direction. Further, in the present invention, the resin of the sheath is defined in the range where the coefficient of static friction according to JIS K 7125 is 0.20 or more.

  The support wire 7 is formed so as to be positioned on substantially the same plane as the optical fiber core wire 3 and the tension member 5. The support wire 7 is made of, for example, a galvanized steel wire.

  The tensile strength of the support wire 7 is appropriately set so as not to break depending on the tension applied to the support wire 7 (optical drop cable 1) during or after installation. Further, in the present invention, the yield point strength of the support wire 7 is further specified in the range of 725 to 1880 MPa, more preferably 905 to 1430 MPa.

  If the yield point strength of the support wire 7 is too high, it will be difficult to wind it around the retainer described later. For example, when the yield point strength exceeds 1430 MPa, the supporting wire 7 is re-wound around the tensioning tool, and in the second winding operation, the winding operation becomes difficult due to the bending rod attached at the first winding. Furthermore, if the yield point strength exceeds 1880 MPa, the first winding operation itself on the retainer becomes difficult.

  If the yield point strength is too weak, or if the coefficient of friction of the resin coated on the support line is too low, the optical drop cable 1 is laid by winding the support line around the tensioning tool, and then tension due to wind or temperature changes. As a result, there is a risk that the support wire 7 will be unwound from the retainer, and further, the support wire 7 may come off the retainer.

  Next, the drawing structure of the optical drop cable 1 will be described. FIG. 2 is a schematic diagram illustrating a pulling-down structure of the optical drop cable 1.

  The trunk cable laid between the pillars 19 that are cable pillars is introduced into a closure 21 formed in the vicinity of the pillar 19. In the closure 21, a necessary optical fiber is branched, connected to the optical drop cable 1, and pulled down to each home, for example.

  For example, the optical drop cable 1 branched and connected from the closure 21 is fastened to a retainer 23 a joined to the pillar 19. FIG. 3A is an enlarged view of a portion A in FIG.

  The retainer 23a includes a support portion 27a and holding portions 29a, 29b, and 29c. The ring-shaped support portion 27 a is fixed to the column 19. The optical drop cable 1 is separated into the support wire portion 15 and the core wire portion 17 in the vicinity of the fixing portion with the retainer 23a. That is, the connecting portion 11 described above is broken.

  For example, a groove or the like is formed on the outer periphery of the holding portions 29a, 29b, and 29c so that the support line portion 15 can be wound around the holding portions 29a, 29b, and 29c. For example, the support line portion 15 is hooked on the holding portion 29a and is wound once around the outer periphery of the holding portion 29b. Further, the supporting wire portion 15 is substantially perpendicular to the winding direction of the holding portion 29b around the holding portion 29c. Wrapped once in the direction and held. That is, the support wire portion 15 is wound around at least two different directions with respect to the retainer 23a.

  Note that the core wire portion 17 of the optical drop cable 1 held by the retainer 23 a is fixed by the tape 31 at a separation portion from the support wire portion 15. By doing as described above, the support wire portion 15 is surely retained by the retainer 23a, and at this time, it is prevented that excessive tension is applied to the core wire portion 17.

  Further, as shown in FIG. 2, the optical drop cable 1 that is held by the drawing tool 23 a supported by the column 19 and in which the core wire portion and the support wire portion are integrated is further drawn by the drawing portion 23 b.

  FIG. 3B is an enlarged view of a portion B in FIG. The retainer 23b has substantially the same configuration as the retainer 23a, but the form of the support portion 27b is different. The support part 27b is a substantially bowl-shaped part, and is hooked on the hanging line 25 (FIG. 2) or the like. Further, the optical drop cable 1 is separated into the core wire portion 17 and the support wire portion 15, and the support wire portion 15 is wound and held around the holding portions 29 a, 29 b, and 29 c as described above. The core wire portion 17 and the support wire portion 15 are fixed with the tape 31 before and after the separation. That is, the support wire portion 15 is retained by the retainer 23b, and excessive tension is prevented from being applied to the core wire portion 17.

  Moreover, as shown in FIG. 2, the optical drop cable 1 laid to the vicinity of the drawing-in destination by the retainer 23b is laid to, for example, a general household building. In the vicinity of the building, the support wire portion 15 and the core wire portion 17 of the optical drop cable 1 are separated, and the retainer 23a is fixed to the building by the retainer 23a, and the core wire portion 17 (the optical drop cable 1 is installed inside the building). ) Is drawn. As described above, a structure for dropping from an aerial cable is configured.

  Next, the influence of the yield point strength of the support line of the optical drop cable of the present invention and the static friction coefficient of the resin of the sheath was investigated. The content of the survey is the handling of optical drop cables with each support line by changing the yield point of the steel wire and the static friction coefficient of the resin of the sheath to multiple levels using a galvanized steel wire with an outer diameter of 1.2 mm as the support line. Workability etc. were evaluated. The optical drop cable used was a tension member (material aramid FRP) having an outer diameter of the support wire portion of 2.0 mm, an outer diameter of the core wire portion of 3.1 × 2 mm, and an outer diameter of 0.5 mm. Using. The target samples and results are shown in Tables 1-3. Samples 1 to 8 shown in Table 1 have a coefficient of static friction of 0.48 according to JIS K 7125 of the sheath resin, and Samples 9 to 16 shown in Table 2 have a coefficient of static friction of 0.20. Yes, Samples 17 to 24 shown in Table 3 have the same static friction coefficient of 0.12. The coefficient of static friction of the sheath resin was adjusted by increasing or decreasing the amount of an additive such as silicone resin added to the sheath resin.

  Wrapping workability around the retainer was evaluated as follows. First, an optical drop cable having a length of 50 m or more was prepared, and a support wire at one end was wound around and fixed to the cable support A with a retainer (the winding method and the shape of the retainer were as shown in FIG. 3A). In the portion to be wound around the retainer, the optical drop cable tears the connecting portion, separates the support wire portion and the core wire portion, and winds only the support wire portion around the retainer.

  Next, while pulling the optical drop cable (support line part) at the opposite end by hand at the cable post B 40 m away from the cable post A, adjust the sag to about 50 cm while adjusting the slack 1 with the same tensioning tool. The winding was fixed for the second time (winding workability to the retainer (first time)).

  Next, the support wire portion wound and fixed by the cable support B was once opened, and this time, the second winding and fixing to the tensioning device was performed again in the same manner while adjusting the slackness to be about 40 cm (straining). Wrapping workability around tools (second time)).

  FIG. 4 is a schematic view showing a state of the wound support line portion 13. When the support line portion 13 was wound around the tensioning device, a gap (for example, C in the figure) generated between the tensioning device and the support line portion in each holding portion was measured. Note that the gap is not limited to the illustrated position, and includes a gap generated at another winding position.

  “Winding workability to the tensioning device (first time)” means that the first winding and fixing is ○ without any problem, the winding itself is possible, but the repulsive force is large. A case where a gap of 1 mm or more was formed between the tensioning devices was indicated by Δ, and a case where a repulsive force was large and a space of 2 mm or more was formed between the support wire portion and the tensioning device after winding was designated as x.

  In addition, “workability on winding device (second time)” means that, when the winding is fixed for the second time, ○ which is wound without any problem, the winding itself is possible, but the bending wrinkle due to the first winding is large, △ If there is a gap of 1 mm or more between the support wire and the retainer after winding, the repulsive force is large, and after winding, a gap of 2 mm or more is created between the support wire and the retainer Was marked with x.

  In addition, “slip of the support wire with the retaining device after the vibration test” was evaluated as follows. First, as shown in FIG. 5, an optical drop cable was laid at a slackness of 40 cm between columns 19 having a span of 40 m. Both ends of the optical drop cable were fixed with a retainer 23a by the same method as in FIG. A vibration exciter 33 was installed in the center of the span, and the optical drop cable was vibrated with an amplitude of 12.5 cm, a vibration frequency of 2 Hz, and a vibration frequency of 100,000. Marking was previously made on the support wire portion wound around the retainer, and the amount of slip before and after vibration was measured.

  Further, “bending wrinkles after feeding out from the bobbin” was evaluated as follows. First, as shown in FIG. 6A, a 1000 m optical drop cable was wound around a resin bobbin 35 having a body diameter of 250 mm and an inner width of 280 mm. The bobbin 35 was installed on a supply stand in which a round bar having a diameter of 40 mm was inserted into a bobbin shaft hole having a diameter of 51 mm. The optical drop cable 1 was drawn out from the bobbin 35 at a speed of about 30 m / min by hand, and the bending wrinkle was evaluated.

  In the optical drop cable after feeding, the linearity of the portion where the bending wrinkles occurred was measured. As shown in FIG. 6 (b), the bending wrinkle is measured by leaving the optical drop cable 1 at any location where the bending wrinkle has occurred without leaving any load, and locating the location where the bending wrinkle has occurred. The height of the arc (F in the figure) was measured with respect to 1 m (E in the figure) as the center. When the height of the arc exceeded 200 mm, it was judged that the bending wrinkles were large, and the number of places where bending wrinkles exceeding 200 mm were generated for the total measurement of 1000 m was counted.

  In addition, “bending rod after passing through No. 2 gold wheel” was evaluated as follows. First, as shown in FIG. 7, the optical drop cable 1 wound around the bobbin 35 is extended substantially vertically and hung on a gold wheel 37 (No. 2 gold wheel) installed at a position of 6.4 m above the ground. It was turned about 90 degrees via the gold wheel 37, and pulled 100m in the substantially horizontal direction at a speed of about 30m / min. For the optical drop cable 1 after being pulled, the bending wrinkle is measured by the same method as in FIG. 6B. If the height of the arc exceeds 200 mm, it is determined that the bending wrinkle is large, and the measurement is 100 m in total. In contrast, the number of bending wrinkles exceeding 200 mm was counted.

  As apparent from Tables 1 to 3, it was found that when the yield strength of the support wire was 1880 MPa or less, the first winding workability to the retainer was excellent. Further, it was found that when the yield point strength is 1430 MPa or less, the workability is excellent even in the second winding operation around the retainer.

  In addition, for samples 1 to 16 having a static friction coefficient of 0.20 or more, if the yield strength of the support wire is 725 MPa or more, “slip of the support wire with the retainer after the vibration test”, “ Both “bending kite after feeding from bobbin” and “bending kite after passing No. 2 gold wheel” are greatly improved. Furthermore, if the yield point strength of the support wire is 905 MPa or more, the occurrence of winding kites, slips, etc. It was hardly seen.

  In Samples 17 to 24, in which the coefficient of static friction was less than 0.20, even when the yield strength of the support wire was 905 MPa or more, the occurrence of slippage in the retainer was often observed.

  Thus, according to the present invention, not only the breaking strength is regulated as in the prior art, but the mechanical properties of the support wire are limited by the yield point strength, and further the static friction coefficient of the sheath resin is limited. Thus, it is possible to provide a cable overhead support wire and an optical drop cable that prevent slipping and coming off from the retainer after laying while suppressing the occurrence of bending wrinkles during laying, while ensuring a good laying workability.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, although the optical drop cable 1 showed the aspect which used the one optical fiber core wire 3, in the optical drop cable 1 of this invention, the number of the optical fiber core wires 3 is not limited to one, Two or more The desired number of can be adopted. Moreover, you may employ | adopt the optical fiber unit which consists of multiple optical fiber core wires 3. FIG.

  Moreover, although the notch 15 is formed in the optical drop cable 1, the notch 15 is not necessarily required. Further, the shape of the notch 7 also has a triangular shape in cross-sectional view, but is not limited thereto, and a notch having an arbitrary shape such as a trapezoidal shape, a semicircular shape, or a sharp blade shape can be formed. .

1 ... Optical drop cable 3 ... Optical fiber core 5 ... Tension member 7 ... Support wire 9 ... Sheath 11 ... Link portion 13 ... Notch 15 ... Support wire portion 17 ......... Core portion 19 ......... Pilla 21 ......... Clamps 23a, 23b ......... Tensioner 25 ......... Suspension wires 27a, 27b ......... Support portions 29a, 29b, 29c ......... Holding portion 31 ……… Tape 33 ……… Exciter 35 ……… Bobbin 37 ……… Gold Wheel

Claims (4)

A self-supporting optical drop cable,
A support line;
An optical fiber core,
A tension member;
A resin that collectively covers the support wire, the optical fiber core wire, and the tension member;
Comprising
The optical drop cable, wherein the support wire is a steel wire having a yield strength of 725 MPa to 1880 MPa, and the resin has a coefficient of static friction according to JIS K 7125 of 0.20 or more.   The optical drop cable according to claim 1, wherein the yield strength of the support wire is 905 MPa to 1430 MPa.   The optical drop cable according to claim 1, wherein the surface of the support wire is galvanized. Using the optical drop cable according to any one of claims 1 to 3,
In the withdrawal portion, the resin that covers the support wire and the resin that covers the optical fiber and the tension member are separated,
A dropping structure for an optical drop cable, wherein the support wire is wound and supported in at least two directions with respect to a retainer.

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