JP2014095732A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical cable in which jacket tearing strings cause no drawing-out from the cable or no tearing defect of a jacket even if they are arranged without consideration of a position thereof embedded in the jacket.SOLUTION: In an optical cable, a cable core 14 is formed such that a plurality of coated optical fibers are protected by an upper winding tape 13 and also tied collectively in a bundle and, on the outside thereof, jacket tearing strings 17 are longitudinally attached and the entirety is covered with a jacket 15 by using extrusion-molding. The jacket tearing strings 17 are bonded and fixed on the surface of the upper winding tape. Furthermore, a contact portion between the upper winding tape 13 and the jacket tearing strings 17 may be subjected to fusion by heat in extrusion-molding the jacket 15 to be bonded and fixed. Also, there are utilized the jacket tearing strings 17 in which a string, made of a thermoplastic resin, melting by heat in extrusion-molding the jacket is twisted together, or which are covered with a layer of the thermoplastic resin.

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.

  For multi-fiber optical cables, either a plurality of optical fiber cores can be left as a single core, or optical fiber tape cores made of several optical fiber cores can be bundled into a cable core, and then the whole is extruded. Is covered with a jacket (also called a sheath). 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 rear branch), the tear string is used to tear a predetermined range of the jacket by pulling 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. Patent Document 3 discloses that the contact width between the tear string and the cable core and the filling rate of the yarn that protects the optical fiber core wire are specified.

JP 2012-173398 A JP 2002-341212 A Japanese Patent No. 3730103

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 any of Patent Documents 1 to 3, 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 actual situation, and even if the jacket tear string is arranged without considering the embedment position in the jacket, pull-out from the cable and poor tearing of the jacket do not occur. An object is to provide an optical cable.

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 a jacket core is vertically bundled on the outside of a cable core that is bundled together and covered with an outer jacket by extrusion molding. The jacket tear string is adhesively fixed to the surface of the upper tape.
In addition, it is preferable that the above-mentioned upper winding tape and the jacket tear string are bonded and fixed by fusion of heat at the time of extrusion molding of the jacket. 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. What is covered can be used.

  According to the present invention, it is only necessary to press the outer jacket tear string vertically on the surface of the upper winding tape of the cable core, and to adhere and fix it to the upper winding tape as it is, and to manage the position where the outer jacket tear string is embedded in the outer jacket. Since it is not necessary to do so, the production speed can be increased. Further, since the jacket tear string is bonded and fixed to the upper winding tape, pull-out is prevented and the jacket can be reliably torn from the inner surface.

It is a figure explaining the outline of the optical cable by this invention. It is a figure which shows an example of the tear string used for this invention. It is a figure which shows the other example of the tear string used for this invention.

  Embodiments of the present invention will be described with reference to the 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, 15a is a ridge, 16 is a tension member, 17 is a tear string, 18 is a support line portion, and 19 is a connecting portion.

  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 is made by stacking and bundling four optical fiber ribbons 11a of four cores to form a 24 core, and covering the outer side with a yarn made of a fiber bundle to form a protection or buffer layer 12 for the optical fiber. A cable core 14 is formed by pressing the outer periphery with an upper winding tape (also referred to as a presser winding tape) 13. The upper tape 13 is usually a non-woven fabric such as polyester fiber.

  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. In the optical cable 10b shown in the figure, six bundles of four optical fiber core wires 11b are assembled into 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, and the outer periphery thereof is wound up. The cable core 14 is pressed by the tape 13.

The optical cables 10a and 10b shown in FIGS. 1 (A) and 1 (B) are provided with a jacket tear string (hereinafter referred to as a tear string) 17 for tearing the jacket in the longitudinal direction on the outside of the cable core 14. The tension member 16 is covered with an outer cover 15 formed by extrusion. For the jacket 15, a polyethylene resin or a flame-retardant polyethylene resin is usually used. The tear string 17 is bonded and fixed in contact with the surface of the upper winding tape 13 of the cable core 14, and a portion that is not bonded is embedded in the jacket 15. 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 pressed directly.

  As in the example of FIGS. 1A and 1B, the optical cable 10c shown in FIG. 1C has a tear string 17 vertically attached to the outer side of the cable core 14 for tearing the jacket in the longitudinal direction. The tension member 16 is covered with an outer cover 15 formed by extrusion. The tear string 17 is bonded and fixed in contact with the surface of the upper winding tape 13 of the cable core 14, and a portion that is not bonded is embedded in the jacket 15. 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 to 10c shown in FIG. 1 are bundled with a plurality of optical fiber core wires or tape core wires, and are made into a cable core with an upper winding tape in a straight state without twisting or twisting without using a slot rod. As shown in the example, it can also be used for an optical cable using a slot rod. When a slot rod is used, a state where a plurality of optical fiber core wires or tape core wires are accommodated in the slot groove and the upper winding tape is wound is defined as a cable core.
Further, the upper winding tape 13 may be in any form of being spirally wound or wound vertically.

  The above-described tear string 17 may be adhered and fixed to the surface of the upper winding tape 13 using an adhesive or the like, but is bonded to the upper winding tape 13 by heat melting by matching the adhesiveness with the upper winding tape material. It may be fixed. In this case, the upper winding tape and / or the tear string, or both, can be heat-melted and fused using the heat at the time of extrusion molding of the jacket.

  2 and 3 are diagrams showing examples of tear strings that are bonded and fixed by heat fusion. FIG. 2 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 20a, 20b 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 20a and 20b to be twisted is a string 21a and 21b of a thermoplastic resin such as low-melting nylon that melts by heat at the time of extrusion molding of the jacket.

  The tear string 17a shown in FIG. 2A is an example in which one of the seven strings is twisted as a thermoplastic resin string 21a. FIG. 2B is a view showing a state where the tear string 17 a is vertically attached to the surface of the upper winding tape 13 and embedded in the outer jacket 15. The tear string 17a is fused intermittently to the surface of the upper tape 13 in the longitudinal direction of the cable as indicated by the fused portion 22a in the longitudinal direction of the cable as the thermoplastic resin string 21 is melted by the heat at the time of extrusion of the outer jacket 15. .

  Further, the tear string 17b shown in FIG. 2C is an example in which one of the three strings is a thermoplastic resin string 21b and twisted. FIG. 2D is a view showing a state in which the tear string 17 b is vertically attached to the surface of the upper tape 13 and embedded in the outer jacket 15. The tear string 17b is intermittently fused and fixed to the surface of the upper winding tape 13 in the longitudinal direction of the cable as indicated by the fused part 22b in the cable longitudinal direction by the thermoplastic resin string 21 being melted by the heat during the extrusion of the jacket. .

  As shown in FIG. 2B and FIG. 2D, by changing the number of small-diameter fiber strings 20a and 20b to be twisted, the fusion interval between the thermoplastic resin strings 21a and 21b and the upper winding tape 13 can be changed. Can be changed. In addition, when the number of the small-diameter fiber strings 20a to be twisted is large as shown in FIG. 2A, the fusion interval with the upper tape 13 can be changed also by increasing the number of the thermoplastic resin strings 21a. it can.

  FIG. 3 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. 2, and is bundled so as to have a predetermined tensile strength, and has a circular cross section as shown in FIG. A fiber cord 23a, a fiber cord 23b having a rectangular cross section as shown in FIG. 3B, or a fiber cord 23c formed by bundling a plurality of small cords as shown in FIG. Is.

The surfaces of the bases of these fiber cords 23a to 23c are covered with layers 24a, 24b, 24c of thermoplastic resin such as low melting point nylon that is melted by heat at the time of extrusion molding of the jacket, and the tear cords 17c, 17d, 17e.
FIG. 3D 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 tape 13 and embedded in the outer jacket 15. The tear strings 17c to 17e are melted continuously as indicated by the fused portion 25 on the surface of the upper tape 13 in the longitudinal direction of the cable as the thermoplastic resin layers 24a to 24c are melted by heat at the time of extrusion molding of the jacket. It is fixed.

  In the present invention, as described above, the jacket tear string disposed between the upper tape and the jacket of the cable core is bonded and fixed to the surface of the upper tape. On the other hand, the tear string may adhere to the outer jacket depending on the material used. However, in the present invention, it does not matter whether the tear string is bonded to the jacket and how much the string is embedded in the jacket, and management for that is not required in manufacturing.

  In the present invention, since the tear string is directly bonded and fixed to the surface of the upper tape of the cable core, the tear string is not pulled out prior to tearing. In addition, there is no case in which the outer jacket material of the extrusion molding is wrapped between the tear string and the upper winding tape and the tear string is completely buried in the outer jacket. For this reason, when the tear string is pulled out, the outer cover does not remain on the upper tape, and the tearing operation can be facilitated.

10a, 10b, 10c ... optical cable, 11a ... optical fiber ribbon, 11b ... optical fiber bundle, 11c ... optical fiber unit, 12 ... buffer layer (yarn), 13 ... upper tape, 14 ... cable core, 15 ... outside Cover, 15a ... ridge, 16 ... tension member, 17, 17a to 17e ... tearing string, 18 ... support line part, 19 ... connecting part, 20a, 20b, 23a-23c ... fiber string, 21a, 21b ... thermoplastic resin , 22a, 22b, 25 ... fused portion, 24a-24c ... thermoplastic resin layer.

Claims (4)

An optical cable in which a plurality of optical fiber cores are protected by an upper winding tape and covered with a jacket by extrusion molding with a jacket tear string attached to the outside of the cable core bundled together,
An optical cable, wherein the jacket tear string is bonded and fixed to a surface of the upper winding tape.   2. The optical cable according to claim 1, wherein a contact portion of the upper winding tape and the jacket tear string is bonded and fixed by heat at the time of extrusion molding of the jacket.   The optical cable according to claim 2, wherein the jacket tear string is formed by twisting a string made of a thermoplastic resin that is melted by heat at the time of extrusion molding of the jacket.   The optical cable according to claim 2, 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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