JP2014119635A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cable in which sheath tear strings are not caused to be drawn out of a cable and a sheath is not subjected to a tearing defect even if the sheath tear strings are arranged without considering an embedment position thereof in the sheath.SOLUTION: In an optical cable, a cable core 14 is formed such that a plurality of coated optical fibers are protected by an upper wrapping tape 13, sheath tear strings 17 are longitudinally attached outside the cable core, and the entirety is covered with a sheath. In the optical cable, a press-winding member 20 is wound around upper surfaces of the upper wrapping tape 13 and the sheath tear strings 17 on the cable core 14.

Description

  The present invention relates to an optical cable in which a jacket tear string is disposed between a cable core in which a plurality of optical fiber cores are bundled and a jacket.

  A multi-core optical cable is, for example, a cable core in which a plurality of optical fiber cores are kept as a single core, or a plurality of optical fiber core wires are bundled into a tape shape and bundled with an upper tape. Then, the whole is covered with an outer cover (also called a sheath) by extrusion molding. Further, a tension member (also referred to as a tensile body) is embedded in the jacket, and a tear string is vertically attached to the inner surface side of the jacket. When a part of an optical fiber core is branched from an intermediate part of an optical cable (also referred to as an intermediate post-branch), the tear string is used to tear a predetermined range of the jacket by pulling out the tear string of the part. It is easy to remove the outer cover.

  Various proposals have been made for tearing the outer jacket so as to effectively tear the outer jacket. For example, Patent Document 1 discloses a protective layer that protects the jacket or a plurality of optical fiber cores by arranging the tear string so that the center of the tear string is positioned on the inner side (optical fiber core side) of the inner surface of the jacket. It is disclosed to adhere and fix to (yarn). Further, Patent Document 2 discloses that the position where the tear string is embedded in the jacket is specified.

JP 2012-173398 A JP 2002-341212 A

  The torn string of the jacket must be provided so that the jacket can be surely torn without being pulled out of the cable when the jacket is torn and not partially remaining on the cable core. For this reason, in both Patent Documents 1 and 2, it is required to strictly manage the embedded state of the tear string in the jacket. However, since the position of the tear string differs depending on the thickness of the optical cable and the thickness of the jacket, fine adjustment or the like is required for setting the burying position, and high-precision control is required. For this reason, it is difficult to increase the manufacturing speed, which is one factor that hinders improvement in productivity.

  The present invention has been made in view of the above-described circumstances, and even if the jacket tear string is arranged without considering the embedment position in the jacket, pulling out from the cable and poor tearing of the jacket are not caused. An object is to provide an optical cable that does not occur.

  An optical cable according to the present invention is an optical cable in which a plurality of optical fiber core wires are protected by an upper winding tape and covered with a jacket with a jacket tear string attached vertically, and the upper winding tape of the cable core. The presser winding member is wound from above the jacket tear string.

  In addition, it is preferable that the contact portion of the upper winding tape and the presser winding member is fused and fixed by heat at the time of extrusion molding of the outer cover. The jacket tear string is a layer of a thermoplastic resin in which a string made of a thermoplastic resin that is melted by heat at the time of extrusion molding of the jacket is twisted or melted by heat at the time of extrusion molding of the jacket. Preferably it is covered.

  According to the present invention, since the jacket tear string is fixed by winding the presser winding member from the upper winding tape and the jacket tear string of the cable core, the position where the jacket tear string is embedded in the jacket is fixed. There is no need to perform management, the production speed can be increased, and the jacket tear string is fixed between the upper winding tape and the presser winding member, so that pull-out is prevented and the outer jacket is It can be torn reliably.

It is a figure which shows an example of the optical cable by this invention. It is a figure which shows the other example of the optical cable by this invention. It is a figure which shows an example of the state which removed the jacket and tension member of the optical cable by this invention. It is a figure which shows the example of the tear string which adheres and fixes by heat sealing | fusion. It is a figure which shows the other example of the tear string which adheres and fixes by heat sealing | fusion.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an optical cable according to the invention will be described with reference to the accompanying drawings. In FIG. 1, 10a, 10b and 10c are optical cables, 11a is an optical fiber ribbon, 11b is an optical fiber bundle, 11c is an optical fiber unit, 12 is a buffer layer (yarn), 13 is an upper tape, and 14 is a cable core. , 15 is a jacket, 16 is a tension member, 17 is a jacket tear string (hereinafter simply referred to as a tear string), 18 is a support line portion, 19 is a connecting portion, and 20 is a presser winding member.

  FIG. 1A is an example of an optical cable using an optical fiber ribbon, and is an example of a multi-fiber optical cable 10a formed by laminating a plurality of tape ribbons. The optical cable 10a shown in the figure has six optical fiber ribbons 11a of four cores stacked and bundled to form 24 cores, and the outer side thereof is covered with yarns made of fiber bundles to provide a protection or buffer layer 12 for the optical fiber cores. The outer periphery is pressed by the upper winding tape 13, and the outer periphery is pressed by the presser winding member 20 to form the cable core 14. In addition, as the upper winding tape 13, nonwoven fabrics, such as a polyester fiber, are normally used. Further, the upper winding tape 13 may be either a spirally wound form or a vertically wound form.

  FIG. 1B shows an example of an optical cable using a single-core optical fiber. For example, several optical fiber cores are bundled and a plurality of bundles are assembled into a multi-core optical cable 10b. is there. The optical cable 10b shown in the figure includes six bundles of four optical fiber core bundles 11b to form 24 cores, and the outer side thereof is covered with a yarn made of fiber bundles to form a protection or buffer layer 12 for the optical fiber core wires. Is pressed by the upper tape 13, and the outer periphery thereof is pressed by the presser winding member 20 to form the cable core 14.

  The optical cables 10a and 10b shown in FIGS. 1 (A) and 1 (B) are provided with a tear string 17 for tearing the outer jacket in the longitudinal direction on the outer side of the upper winding tape 13, and with the tension member 16 by extrusion molding. Covered with a cover 15. For the jacket 15, a polyethylene resin or a flame-retardant polyethylene resin is usually used. The tear string 17 is in contact with the surface of the upper winding tape 13 of the cable core 14, and the presser winding member 20 is wound from above the upper winding tape 13 and the tear string 17 of the cable core 14. The burying position of the tear string 17 is displayed by, for example, integrally forming the protrusion 15a on the surface of the outer jacket 15. Moreover, although it has shown with the form which does not have a support line part in this example, it is good also as a form which has a support line part similarly to having shown in the following FIG.1 (C).

  FIG. 1C is an example of an optical cable using an optical fiber unit. For example, a plurality of optical fiber cores are assembled into an optical fiber unit, and a plurality of these units are assembled into a multi-core optical cable 10c. . In this example, the support line portion 18 is provided integrally with the optical cable via the connecting portion 19. However, the support line portion 18 may be omitted. The optical cable 10c shown in the figure, for example, collects 20 optical fiber cores into an optical fiber unit 11c, collects 10 units into 200 optical fibers, and the outer periphery thereof is not provided with a buffer layer with the upper tape 13. The cable core 14 is formed by directly pressing the outer periphery and pressing the outer periphery with the presser winding member 20.

  The optical cable 10c shown in FIG. 1 (C) is provided with a tear string 17 for tearing the outer jacket in the longitudinal direction on the outer side of the upper winding tape 13 in the same manner as in the example of FIGS. 1 (A) and 1 (B). The tension member 16 is covered with an outer cover 15 formed by extrusion. The tear string 17 is in contact with the surface of the upper winding tape 13 of the cable core 14, and the presser winding member 20 is wound from above the upper winding tape 13 and the tear string 17 of the cable core 14. The burying position of the tear string 17 is displayed by, for example, integrally forming the protrusion 15a on the surface of the outer jacket 15.

  The optical cables 10a, 10b, and 10c are formed by bundling a plurality of optical fiber cores or optical fiber tape cores, and winding them in a straight state without twisting or twisting without using a slot rod (also referred to as a spacer). However, it may be an optical cable having a cable core using a slot rod. When the slot rod is used, a plurality of optical fiber core wires or tape core wires are accommodated in the slot grooves, and a state where the upper winding tape is wound is defined as a cable core.

  FIG. 2 shows an optical cable using optical fiber ribbons as in FIG. 1A. The optical cable 10d is a stack of four optical fiber ribbons 11d and bundled into a slot rod 27. However, it is in a state of being held by the upper winding tape 13 or the presser winding member 20. This optical cable 10d is constituted by a resin-made slot rod 27 in which a tension member 16 is embedded and integrated at the center and a plurality of storage grooves 27a are provided. The storage grooves 27a have a bottom surface on the tension member 16 side, and are arranged at substantially equal intervals along the circumferential direction of the slot rod 27. Adjacent storage grooves 27a are separated by ribs 27b.

  The storage groove 27a is formed in a spiral shape or an SZ shape along the longitudinal direction of the optical cable 10d, and the four optical fiber tape cores 11d laminated are stored in the storage groove 27a. In the state where the optical fiber ribbon 11d is stored in the storage groove 27a, the upper winding tape 13 is applied to the outer periphery of the slot rod 27, and the outer periphery is pressed by the press-winding member 20 to form the cable core 14.

  In addition, on the outside of the slot rod 27 and on the inside of the upper winding tape 13, rough winding such as nylon thread or plastic tape may be performed. The upper winding tape 13 is wound in the longitudinal direction of the optical cable 10d, holds the optical fiber ribbon 11d stored in the storage groove 27a so that it does not jump out, and forms the outer cover 15. It is also possible to provide a water-absorbing agent for functioning as a water-absorbing layer by applying a water-absorbing agent for stopping heat into the heat insulating layer or the optical cable.

  FIG. 3 is a view showing an example of a state in which the jacket and the tension member of the optical cable according to the present invention are removed. In the case of this example, the upper winding tape 13 is vertically attached in the longitudinal direction of the cable core 14, and is wound in a state where the tape end 13a is overlapped with the overlapping width D shown in FIG. In order to suppress the opening of the upper winding tape 13, a string-like presser winding member 20 is wound around the surface of the upper winding tape 13. The presser winding member 20 is spirally wound horizontally around the vertically attached upper winding tape 13, and is roughly wound at a pitch that does not open the upper winding tape 13.

  A main object of the present invention is to prevent pull-out from a cable and poor tearing of a jacket even if a tear string is arranged without considering the position of embedment in the jacket. As a configuration for this purpose, the presser winding member 20 is wound from above the upper winding tape 13 and the tear string 17 of the cable core 14. That is, as shown in FIG. 3, the tear string 17 is sandwiched and fixed between the upper winding tape 13 and the presser winding member 20. For this reason, the tear string is not pulled out prior to tearing, and when the tear string is pulled out, the outer cover does not remain on the upper winding tape, and the tearing operation can be facilitated. Moreover, since it is not necessary to manage the position where the tear string is embedded in the outer jacket, the production speed can be increased.

  Here, as the tear string 17, for example, polyester fiber, aramid fiber, or the like can be used. In order to fix the tear string 17 as described above, the upper winding tape 13 and the presser winding member 20 include It is preferable that the contact portion is fused and fixed by heat at the time of extrusion molding of the jacket 15. Specifically, the press-wound member 20 can be bonded and fixed to the surface of the upper-winding tape 13 by heat melting by matching the fusion properties of the upper-winding tape 13 and the press-wound member 20.

  For example, a thermoplastic resin such as low melting point nylon is used as the presser winding member 20. This resin has a property of not adhering to the jacket 15 and a property of melting at a temperature lower than the melting point (about 200 ° C.) of the jacket 15. Thereby, the upper winding tape 13 and the presser winding member 20 can be bonded and fixed by heat melting. It should be noted that the presser winding member 20 is cut by hand when the presser winding member 20 is exposed when the outer cover 15 is removed due to a decrease in breaking strength due to heat during extrusion of the outer cover 15. Can do. Since the strength of the presser winding member 20 is weaker than that of the tear string 17, the presser winding member 20 can be easily cut when the outer cover 15 is torn with the tear string 17 in the longitudinal direction. In the present invention, the tear string 17 is disposed on the lower side of the presser winding member 20, but the presser winding member 20 does not interfere with the tearing operation by configuring as described above.

  Further, in order to more effectively prevent the tear string 17 from being pulled out, it is preferable that the tear string 17 is bonded and fixed to the presser winding member 20 or the upper winding tape 13 by heat fusion at the time of extrusion molding of the jacket 15. . This will be described with reference to FIGS.

  4 and 5 are diagrams showing examples of tear strings that are bonded and fixed by heat fusion. FIG. 4 shows an example in which a plurality of strings are twisted to form a tear string having a predetermined tensile strength. In this example, polyester fibers, aramid fibers, and the like are twisted together. For example, a plurality of fiber strings 21a, 21b twisted to a small diameter are further twisted to form tear strings 17a, 17b. it can. In this case, at least one of the small-diameter fiber strings 21a and 21b to be twisted is used as a thermoplastic resin string 22a and 22b such as low-melting-point nylon that is melted by heat at the time of extrusion molding of the jacket.

  The tear string 17a shown in FIG. 4 (A) is an example in which one of the seven strings is twisted as a thermoplastic resin string 22a. FIG. 4B is a view showing a state in which the tear string 17 a is vertically attached to the surface of the upper winding tape 13 and arranged below the presser winding member 20. The tear string 17a is fused and fixed intermittently as indicated by the presser winding member 20 and the fused portion 23a, as the thermoplastic resin string 22a is melted by the heat of the outer casing 15 during extrusion molding. In the case of this example, the fused portion 23a of the tear string 17a is also intermittently fused and fixed to the surface of the upper tape 13 by heat during extrusion. For this reason, since the tear string 17a is fixed between the presser winding member 20 and the upper winding tape 13, it can prevent pulling out more effectively.

  Further, the tear string 17b shown in FIG. 4C is an example in which one of the three strings is a thermoplastic resin string 22b and twisted. FIG. 4D is a view showing a state in which the tear string 17 b is vertically attached to the surface of the upper winding tape 13 and is arranged below the presser winding member 20. The tear string 17b is fused and fixed intermittently as indicated by the presser winding member 20 and the fused portion 23b, as the thermoplastic resin string 22b is melted by the heat of the outer casing 15 during extrusion molding. In the case of this example, similarly to the above, the fused portion 23b of the tear string 17a is also intermittently fused and fixed to the surface of the upper tape 13 by heat during extrusion. For this reason, since the tear string 17b is fixed between the presser winding member 20 and the upper winding tape 13, it can prevent pulling out more effectively.

  As shown in FIG. 4B and FIG. 4D, by changing the number of small-diameter fiber strings 21a and 21b to be twisted, the presser winding member 20 or the upper winding tape 13 by the thermoplastic resin strings 22a and 22b The fusion interval can be changed. 4A, when the number of small-diameter fiber cords 21a to be twisted is large, fusion with the presser winding member 20 or the upper winding tape 13 can also be achieved by increasing the number of the thermoplastic resin cords 22a. The interval can be changed. The spacing between the thermoplastic resin strings 22a and 22b and the winding pitch of the presser winding member 20 do not necessarily coincide with each other, but according to the spacing between the thermoplastic resin strings 22a and 22b, The winding pitch may be determined.

  FIG. 5 shows an example in which the surface of the tear string is covered with a layer of a thermoplastic resin that is melted by heat at the time of extrusion molding of the jacket. This example is formed by twisting polyester fibers, aramid fibers, etc. in the same manner as in the example of FIG. 4, and is bundled so as to have a predetermined tensile strength, and has a circular cross section as shown in FIG. 5 (A). The fiber cord 24a, the fiber cord 24b having a rectangular cross section as shown in FIG. 5B, or the fiber cord 24c formed by bundling a plurality of small cords as shown in FIG. Is.

  The surface of the base of these fiber cords 24a to 24c is covered with layers 25a, 25b, 25c of thermoplastic resin such as low-melting nylon that is melted by heat at the time of extrusion molding of the jacket, and the tear cords 17c, 17d, 17e.

  FIG. 5D is a view showing a state in which the tear strings 17 c to 17 e are vertically attached to the surface of the upper winding tape 13 and embedded in the outer jacket 15. The tear strings 17 c to 17 e are melted and fixed intermittently as indicated by the presser winding member 20 and the fused portion 26, as the thermoplastic resin layers 25 a to 25 c are melted by heat at the time of extrusion molding of the outer jacket 15. . In the case of this example, the tear strings 17c to 17e are continuously fused to the surface of the upper winding tape 13 in the longitudinal direction of the cable because the thermoplastic resin layers 25a to 25c are melted by heat at the time of extrusion molding of the jacket. Fixed.

10a, 10b, 10c, 10d ... Optical cable, 11a, 11d ... Optical fiber ribbon, 11b ... Optical fiber bundle, 11c ... Optical fiber unit, 12 ... Buffer layer (yarn), 13 ... Upper wound tape, 14 ... Cable core 15 ... jacket, 15a ... ridge, 16 ... tension member, 17, 17a-17e ... tearing string, 18 ... support line part, 19 ... coupling part, 20 ... presser winding member, 21a, 21b, 24a-24c ... Fiber string, 22a, 22b ... thermoplastic resin string, 23a, 23b, 26 ... fused portion, 25a-25c ... thermoplastic resin layer, 27 ... slot rod, 27a ... storage groove, 27b ... rib.

Claims (4)

An optical cable in which a plurality of optical fiber core wires are protected by an upper winding tape and covered with a jacket with a jacket tear string attached vertically,
An optical cable, characterized in that a presser winding member is wound from above the upper winding tape of the cable core and the jacket tear string.   The optical cable according to claim 1, wherein a contact portion of the upper winding tape and the presser winding member is fused and fixed by heat at the time of extrusion molding of the jacket.   The optical cable according to claim 1 or 2, wherein the outer jacket tear string is formed by twisting a string made of a thermoplastic resin that is melted by heat during extrusion of the outer casing.   The optical cable according to claim 1, wherein the jacket tear string is covered with a layer of a thermoplastic resin that is melted by heat during extrusion of the jacket.

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