JP2014032302A - Communication cable and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication cable in which a tear cord not only can be easily taken out but also does not easily come off from an outer cover, and a manufacturing method thereof.SOLUTION: The communication cable is covered with an outer coating 12 on the outer periphery of a core cable 11 and embedded with a tear cord 13 on the inner surface side of the outer coating. The tear cord 13 is configured to be embedded in such a manner that a part 14a in which there is an air gap with the outer coating 12 is intermittently present in a longitudinal direction of the cable. The continuous length of a part 14b in which there is no air gap is less than 30 mm, and the cross section of a hole of the part 14a in which there is the air gap is 1.5 times or more of the cross section of the tear cord 13 in a state where the tear cord is not present.

Description

  The present invention relates to a communication cable in which a jacket tear string is embedded between a cable core and a jacket, and a method for manufacturing the communication cable.

  A communication cable is usually configured by covering the outer periphery of a cable core in which signal wires such as a plurality of optical fibers and electric wires are bundled with an outer jacket (also referred to as a sheath) by extrusion molding. Further, the communication cable is pulled down to a house or the like by drawing a signal line from the middle part of the cable after laying. In this case, the outer sheath of the cable is removed by a predetermined length in the longitudinal direction to expose the internal signal line. However, in order to facilitate the removal of the outer sheath, a string for tearing the outer sheath ( 2. Description of the Related Art A communication cable is known that has a structure in which an outer wrapping cord (also referred to as a lip cord) is embedded and a jacket is cut off by the tear string (see, for example, Patent Document 1).

  In the above-mentioned Patent Document 1, a tear string is inserted into a concave groove formed of a circular cavity having a partially opened circumference on the inner surface of the jacket, and the position of the tear string is indicated in order to indicate the position of the tear string. It is disclosed to provide a ridge indicating the position of the tear string on the surface of this. It is also disclosed that the opening of the concave groove is intermittently closed so that the tear string does not jump out of the concave groove.

JP 2001-264602 A

  When removing the jacket of the communication cable in which the tear string is embedded, it is necessary to first expose the string that is the starting end of the tear. Although the outer cover may be exposed by cutting it with a cutter or the like, the tear string may be cut. On the other hand, when a protrusion indicating the position of the tear string as disclosed in Patent Document 1 is provided on the outer jacket surface, the tear string is exposed by partially scraping the protrusion with a peeler or a cutter. It becomes possible to make it.

  However, if the tear string is embedded so as to be in close contact with the jacket, there is a possibility that even when the jacket is trimmed, the tear string may be scraped off, and there is a problem that it is difficult to take out the tear string. On the other hand, as in Patent Document 1, the above problem can be avoided if there is a gap between the jacket and the tear string in the form of inserting the tear string into the concave groove. However, if there is a gap between the jacket and the tear string, there is a problem that if the jacket removal position is close to the cable end, it will slip out and the jacket cannot be torn.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a communication cable in which a tearing string can be easily taken out and from which the tearing string does not easily come off from a jacket and a manufacturing method thereof.

The communication cable according to the present invention is a communication cable in which the outer periphery of a cable core is covered with a jacket, and a tear string is embedded on the inner surface side of the jacket, and the tear string has a gap between the jacket and the jacket. The portion is embedded so as to be intermittently present in the longitudinal direction of the cable.
In addition, the continuous length of the portion where no void is present is less than 30 mm, and the hole cross-sectional area of the portion where the void is present is 1.5 times or more the cross-sectional area of the tear string in the state where no tear cord exists. It is preferable.

  The above-described method for manufacturing a communication cable is such that oil or moisture is intermittently applied in the longitudinal direction of the cable to the tear string embedded in the jacket before the jacket is extruded, and heat during extrusion of the jacket is formed. By evaporating the oil or moisture, a gap is intermittently formed between the tear string and the jacket.

  According to the present invention, a part of the ridge of the outer jacket can be easily pulled out from the outer jacket without damaging the tear string by shaving with a peeler or a cutter. Then, by pulling and pulling the pulled tear string by hand, the jacket can be cut without being pulled out from the jacket.

It is a figure explaining an example of the communication cable by this invention. It is a figure explaining an example of the manufacturing method of the communication cable by this invention.

  An outline of a communication cable according to the present invention will be described with reference to FIG. In FIG. 1, 10 is a communication cable, 11 is a cable core, 12 is a jacket, 12a is a ridge, 13 is a tear string, 14a is a gap portion, and 14b is a close contact portion.

  The communication cable which is the subject of the present invention can be applied to any of an optical cable having a large number of optical fibers as signal lines, and an electric cable having a large number of insulated wires or coaxial wires as signal lines. However, as shown in FIG. 1A, the cable structure is such that the outer periphery of a cable core 11 in which a large number of signal wires are bundled is covered with a jacket 12 formed by resin extrusion, and is in contact with the inner surface of the jacket 12. It is a communication cable in a form in which at least one tear string 13 is embedded in the outer cover 12 or not in contact with the inner surface of the outer cover 12, that is, on the inner surface side of the outer cover 12. In addition, as a display means which shows an embedding position, it can display, for example with the protrusion 12a which is illustrated to a figure, and can display with a colored line.

For example, polyethylene or flame-retardant polyethylene is used for the jacket 12, but is not limited thereto. The tear string 13 may be a string obtained by bundling high-strength fibers such as aramid fibers, or an impregnated or coated resin.
Note that a tension member (strength member) may be embedded in addition to the tear string 13 embedded in the jacket 12. Alternatively, a self-supporting communication cable in which the jacket 12 that covers the cable core 11 and the support wire portion that covers a steel wire or the like via a narrow connecting portion may be provided.

  In the case where the signal line of the communication cable is an optical fiber, the cable core 11 is a cable core having a shape in which a plurality of optical fiber cores are aggregated and bundled in a circular shape with a tape or the like, or an upper tape using a slot rod A bundle can be used. When the signal line of the communication cable is a metal wire, the cable core 11 has a shape in which a plurality of insulated wires or coaxial wires are assembled, or a common shield is provided and bundled in a circular shape with tape or the like. Can be used.

  The present invention is a communication cable as described above, as shown in FIG. 1 (B) to FIG. 1 (D), where a gap exists between the jacket 12 and the tear string 13 (hereinafter referred to as a gap portion). 14a is provided intermittently. Between this gap portion 14a and the next gap portion 14a, a portion 14b where no gap exists (hereinafter referred to as a close contact portion) is in close contact with or bonded to the outer jacket 14, so that the tear string 13 does not come out of the outer jacket 14. Has been.

  When tearing and removing the intermediate portion of the jacket 12, the tear string 13 serving as the starting end of the tear is required to be about 30 mm, so that the length of the jacket being scraped in the longitudinal direction is at least 30 mm. For this reason, it is preferable that the length L with which the contact | adherence part 14b continues is formed with less than 30 mm. Accordingly, if the portion of the ridge 12a of the jacket is cut at least 30 mm in the longitudinal direction of the cable, there is always a gap portion 14a within that range, so that the tear string 13 is exposed from this gap portion 14a. The outer cover 12 may be scraped off.

  Moreover, the hole of the space | gap part 14a through which the tear string 13 passes may be opened by the inner surface side of a jacket as shown in FIG.1 (C). In this case, when the outer jacket 12 is torn with the tear string 13, the remaining tear of the outer jacket can be reduced. However, the width of the opening is preferably smaller than the thickness of the tear string 13. Moreover, it is preferable that the hole cross-sectional area of the space | gap part 14a along which the tear string 13 passes has 1.5 or more times the cross-sectional area of the tear string 13 in the state in which a tear string does not exist. If there is a gap of this level, it is possible to avoid the tear string 13 from adhering to or adhering to the jacket 12.

  In the communication cable configured as described above, when the outer cover 12 is removed to branch the signal line in the cable, the portion of the ridge 12a indicating the embedded position of the tear string 13 with a peeler or a cutter is described above. As a result, it is shaved at least about 30 mm in the longitudinal direction. When this ridge 12a is scraped off, the gap portion 14a is exposed prior to the contact portion 14b, and the tear string 13 is exposed, so that it is possible to know that the scraping of the jacket has reached a predetermined amount. It is possible to prevent the tear string 13 from being damaged by shaving. The tear string 13 can be easily pulled out from the contact portion 14b whose thickness is reduced by scraping based on the exposed portion of the tear string, and can be made long enough to be grasped by hand. . Then, the outer cover 12 is cut in the longitudinal direction with the tear string pulled out from the outer cover as the starting end.

FIG. 2 shows a jacket forming apparatus showing an example of a method for forming intermittent gap portions 14 a between the jacket 12 and the tear string 13 described above.
The jacket forming device 20 is a device that coats the outer periphery of the cable core 11 with a jacket 12 formed by extrusion, and the cable core 11 is fed from a core supply reel 21 by a core take-up device 22. In the cable core 11, a pair of tear strings 13 fed out from the two string supply reels 23 are vertically attached to the opposite side surfaces of the cable core and transferred to the extruder 25.

  In the present invention, the cable core 11 and the tear string 13 are intermittently moved in the longitudinal direction of the cable at predetermined intervals by the coating device 24 on the near side where the cable core 11 and the tear string 13 are transferred to the extruder 25. Is granted. After that, the tear string 13 is covered and embedded with the outer cover 12 extruded by the extruder 25 so as to contact the cable core 11. At this time, the oil or moisture applied to the tear string 13 is vaporized by the heat generated when the jacket 12 is pushed out, and a gap is formed between the tear string 13 and the jacket 12. This gap can be formed intermittently as described in FIG.

  After that, the cable on which the jacket 12 has been applied by the extrusion molding machine 25 is cooled and hardened by the cooling device 26 and taken by the cable take-up device 27. The communication cable 10 taken up by the cable take-up device 27 is taken up by a take-up reel (not shown).

DESCRIPTION OF SYMBOLS 10 ... Communication cable, 11 ... Cable core, 12 ... Outer jacket, 12a ... Ridge, 13 ... Tear string, 14a ... Space | gap part, 14b ... Close_contact | adherence part, 20 ... Outer-molding apparatus, 21 ... Core supply reel, 22 ... Core take-up device, 23 ... string supply reel, 24 ... coating device, 25 ... extrusion molding machine, 26 ... cooling device, 27 ... cable take-up device.

Claims (4)

A communication cable in which the outer periphery of the cable core is covered with a jacket, and a tear string is embedded on the inner surface side of the jacket,
The communication cable, wherein the tear string is embedded so that a portion where a gap exists between the tear cord and the outer jacket is intermittently present in the longitudinal direction of the cable.   The communication cable according to claim 1, wherein a continuous length of the portion where the gap does not exist is less than 30 mm.   3. The communication cable according to claim 1, wherein a hole cross-sectional area of a portion where the gap is present is 1.5 times or more of a cross-sectional area of the tear string in a state where the tear string does not exist. .   It is a manufacturing method of the communication cable of any one of Claims 1-3, Comprising: Before a jacket is extrusion-molded, oil or water | moisture content is given to the tear string embedded in the jacket in the cable longitudinal direction. A communication cable characterized by being intermittently applied and vaporizing the oil or moisture by heat during extrusion of the jacket to intermittently form a gap between the tear string and the jacket. Production method.

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