JP2007163531A - Optical fiber cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cable in which its main body part and support wire part are easily separated by a manual tearing force although they are inseparable during the installation of the cable and in which no breaking is caused in the optical fiber when it is torn. <P>SOLUTION: This is a self-support type optical fiber cable in which the main body part 1 and the support wire part 2 are integrally connected with a neck part 3. In the main body part 1, four or more coated optical fibers 4 are arrayed in two rows, with a tension member 5 arranged on both sides in the arraying direction and coated altogether including the neck part with a straight chain low density polyethylene, wherein the thickness of the neck part 3 is set at 0.33-0.40 mm. The neck part 3 may have a thickness of 0.40 mm and a shape having a notch with an angle of ≥60°. The coated optical fibers 4 are suitably used even with a protective coating applied thereto with an outer diameter of 0.50 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a self-supporting type optical fiber cable having a relatively small number of core wires, such as a drop cable used for laying between outdoor power poles or drawing indoors.

  With the rapid spread of the Internet, etc., in addition to increasing the speed of information communication and increasing the amount of information, the construction of an optical network for two-way communication and large-capacity communication has recently progressed. FTTH (Fiber To The Home) service that provides high-speed communication services has been started. For this reason, the demand of the optical fiber cable said to be a drop cable used for drawing in in the house is increasing.

  For example, as shown in FIG. 1A, this type of optical fiber cable is configured by integrally connecting a main body 1 and a support wire 2 with a neck 3 that can be easily separated (for example, Patent Document 1). reference). The main body 1 is configured by arranging tension members 5 in parallel on both ends in the arrangement direction of a plurality of optical fiber cores 4 and covering and housing them integrally with a main body jacket 6. Also, notches 7 for tearing are provided on both side surfaces of the body jacket 6 so that the inner optical fiber core wire 4 can be easily taken out. The support wire portion 2 is configured by covering a support wire 8 made of a high-strength wire such as a steel wire with a support wire portion jacket 9 that is formed simultaneously with the molding of the main body portion cover 6.

When laying the optical fiber cable, the support wire portion 2 is partially separated from the main body portion 1 in order to fix the structure to the structure by applying tension or to pull the main body portion 1 into a closure or the like. Moreover, also when using as it is for indoor optical wiring, the support wire part 2 is used separately from the main body part 1. For this reason, the main-body part 1 and the support line part 2 are connected and integrated through the narrow neck part 3 which can be easily separated by hand. However, in the normal use form, the main body 1 is coupled and connected so as to be firmly suspended and supported by the support line 2.
JP 2003-90942 A

  However, in order to improve the workability of laying the optical fiber cable, an optical fiber core with a coating outer diameter of 0.5 mm thicker than a conventional protective coating (the outer diameter of the coating is about 0.25 mm) may be used. . In addition, there is a case in which a relatively hard linear low density polyethylene (abbreviation: L-LDPE) is used for the cable jacket in order to withstand squeezing with a metal wheel roller during installation or wind and snow. The neck connecting the support wire and the main body is generally separated with a dedicated tool and the support wire is fixed to a utility pole or the like with a metal fitting. The thickness D of the neck is approximately 0.45 mm to 0.55 mm. However, it is desired to tear easily by hand without using a dedicated tool.

  In addition, when the optical fiber cores are arranged in multiple stages (for example, three or more stages), if the optical fiber cores become thicker, the upper and lower end optical fibers that deviate from the bending center of the cable are subjected to greater strain than before and are broken. There is a high possibility of mind. The thickness D of the neck is generally 0.45 mm to 0.55 mm. However, when the support wire portion and the main body portion are separated by hand, the optical fiber core is frequently broken. Lines are arranged in two stages or less.

  The present invention has been made in view of the above-described circumstances, and the main body portion and the support wire portion are not separated when the cable is laid, but can be easily separated by a tearing force by hand, and the optical fiber is disconnected when tearing. It is an object to provide an optical fiber cable that does not cause a heart.

  An optical fiber cable according to the present invention is a self-supporting type optical fiber cable in which a main body part and a support line part are connected and integrated by a neck part, and the main body part has four or more optical fiber cores arranged in two rows. The tension members are arranged on both sides in the arrangement direction and are collectively covered with linear low density polyethylene together with the neck, and the thickness of the neck is 0.33 mm to 0.40 mm. The thickness of the neck may be 0.40 mm, and a notch with an angle of 60 ° or more may be provided. The optical fiber core wire is also suitable when a protective coating having a coating outer diameter of 0.50 mm is applied.

  According to the present invention, the main body portion and the support wire portion of the optical fiber cable have a strength that is not easily separated by the work at the time of laying, but can be easily torn and separated by hand. Further, even when the main body portion and the support wire portion are torn by hand, it is possible to prevent the inner optical fiber core wire from being broken. Furthermore, by using linear low density polyethylene, it becomes possible to reduce the thickness of the neck portion while maintaining sufficient mechanical strength against external force such as ironing, and to reduce the amount of coating material used.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining the outline of the present invention, FIG. 2 is a diagram for explaining the tearability of a main body portion and a support wire portion of an optical fiber cable, and FIG. 3 is a diagram for explaining a method for measuring the anti-corrosion strength of a cable. 4 is a diagram for explaining the ironing strength of the optical fiber cable. In the figure, 1 is a main body part, 2 is a support line part, 3 is a neck part, 4 is an optical fiber core wire, 5 is a tension member, 6 is a body part outer cover, 7 is a tear notch, 8 is a support line, and 9 is a support line. A support line portion jacket 10 indicates a notch.

  As shown in FIG. 1A, an optical fiber cable C according to the present invention is a self-supporting optical fiber cable composed of a main body portion 1 and a support wire portion 2, and has a narrow width between the main body portion 1 and the support wire portion 2. This is a structure in which the neck portion 3 is connected and integrated. The main body 1 includes four to a dozen optical fiber cores 4 arranged in two stages, tension members 5 arranged in parallel on both sides in the arrangement direction of the optical fiber cores 4, and a main body jacket 6. It is constructed by covering and housing together.

  The main body jacket 6 constituting the main body 1 is made of linear low-density polyethylene (abbreviation: L-LDPE), which is a relatively hard class among polyethylene resins, and is sufficient for ironing roller wheels and wind and snow. Ensure that it is strong enough to withstand. Further, the main body 1 is formed in a rectangular shape having both side surfaces parallel to the straight line Y passing through the centers of the optical fiber core wire 4 and the tension member 5, but the corners are rounded, resulting in an oval shape or The shape may be close to an elliptical shape. A tear notch 7 can be provided on both side surfaces of the body jacket 6 so that the internal optical fiber core wire 4 can be easily taken out as in the conventional case. The slit notch 7 can be formed in a V shape having a trapezoidal shape or a general shape as shown in the figure.

  The support wire portion 2 is configured by covering a support wire 8 made of a high tensile strength wire such as a steel wire with a support wire portion jacket 9. The support wire portion jacket 9 is formed of the same resin material as that of the main body portion jacket 6 and is integrally formed through the narrow neck portion 3 simultaneously with the formation of the main body portion jacket. Thereby, the optical fiber core wire 4, the tension member 5, and the support wire 8 are integrated. When laying the optical fiber cable, the support wire portion 2 is cut at a predetermined position, and tension is applied to both ends so as to be fastened and fixed to a structure such as a utility pole. In this case, the main body part 1 and the support line part are formed by cutting the neck part 3 at the cut end of the support line part 2 and tearing the neck part 3 by a method as shown in FIG. 2 is separated.

  In the present invention, the number of optical fiber cores is arranged in two stages from four to ten and several so as to reduce strain applied to the optical fiber when the cable is bent. The optical fiber core 4 is reinforced with a glass fiber having a standard outer diameter of 0.125 mm coated with a protective coating having a coating outer diameter of about 0.25 mm, or a protective coating having a coating outer diameter of about 0.50 mm. Can be used. When the coating outer diameter of the optical fiber core wire 4 is increased, when the main body 1 is torn from the support wire portion 2, the strain applied to the optical fiber core wire is increased, and breakage is likely to occur. By setting the number of stages of the optical fiber array to two, it is possible to prevent a large distortion from occurring even with respect to an optical fiber core having a coating outer diameter of 0.50 mm.

  The tension member 5 arranged in parallel to the optical fiber core wire 4 may be a steel wire or a tensile wire such as glass fiber reinforced plastic (FRP) or aramid fiber reinforced plastic (K-FRP). The tension member 5 in the present invention is arranged on the central axis Y passing through the centers of the main body 1 and the support wire 2 so as to sandwich the optical fiber core wire 4 from both sides in the arrangement direction.

  The neck portion 3 connecting the main body portion 1 and the support wire portion 2 has a narrow thickness D and is formed with a separation distance L between the main body portion and the support wire portion. In the present invention, the separation distance L of the neck portion 3 is Usually, it is about 0.2 mm, and the thickness D is set to 0.33 mm to 0.40 mm as will be described later. The thickness of the neck usually has a maximum value and a minimum value of a certain width. Since it is the minimum thickness that affects the strength of the neck, in the present invention, the thickness of the neck is defined as the minimum thickness in the neck cross section. Moreover, as shown to FIG. 1 (B), it can make it easier to tear by putting the V-shaped notch 10 for tearing into the side surface of the neck part 3. FIG. However, depending on the thickness of the neck portion 3 and the angle α of the notch 10, the main body portion 1 and the support wire portion 2 are easily separated and the ironing strength is significantly reduced. The depth D is 0.40 mm and the angle α of the notch is 60 ° or more.

  For example, as shown in FIG. 2 (C), the main body 1 and the support wire 2 are torn at the end of the neck 3 and then the main body 1 is torn relative to the support wire 2. This is done by tearing in the direction of the arrow at θ. At this time, the force F applied to the main body 1 becomes the tearing force. The tear angle θ is generally 90 ° or less, but depending on the worker, there are people who tear at a larger angle, so there is a possibility that a break will occur unless the tear force is reduced.

  FIG. 2A is a diagram showing the relationship between tearing force and tearing ease. When the tearing force is 35 N or less, tearing is possible, but when it is 40 N or more, tearing becomes difficult. Further, if the tearing force is reduced more than necessary, the mechanical strength is lowered, and the main body 1 and the support wire 2 may be separated at the time of laying. Accordingly, the tearing force can be 10N to 35N, but preferably the tearing force is in the range of 15N to 25N based on the results of FIG. 2B described below and FIG. 4A described later. Is desirable.

  FIG. 2B is a diagram showing a result of examining a relationship between a tear failure (decentered) caused by a tear force and a notch angle θ for tearing. Prepare an optical fiber cable with the shape described in FIG. 1A (optical fiber coating outer diameter 0.50 mm) with different neck thickness D and different tearing force, and tear the 50m length. The number of tear failures was investigated by changing the angle θ. Assuming that the tear angle θ is 135 °, 150 °, and 180 °, no breakage occurs when the tear force is 25 N or less when θ = 135 °, and two breaks occur when the tear force is 25 N when θ = 150 °. At an angle of θ = 180 °, the decentering occurs with a tearing force of 15N.

  However, the tearing angle θ is normally performed at 90 ° or less, and even if it is bent at 90 ° or more, it is assumed that it is at most less than 150 °. As a result, the tearing force is desirably 25 N or less.

  FIG. 3 is an example of measuring the ironing strength of an optical fiber cable. By applying a predetermined pulling force P to the optical fiber cable C and reciprocatingly moving on the arcuate surface S of the roller R having the radius r, the state in which the neck portion connecting the main body portion and the support wire portion is separated by breaking was examined. Is. The strength at which the optical fiber cable C is pressed against the arcuate surface S of the roller R (scoring resistance) is varied depending on the magnitude of the pulling force P, and the pulling force P when the neck portion breaks was measured. The optical fiber cable C was the same as that used in the measurement of FIG. 2B, and the radius r of the roller R was 25 cm.

  FIG. 4A shows the “scoring resistance” of the optical fiber cable shown in FIG. As a result, when the tearing force is 10 N (neck thickness D = 0.20 mm), the ironing force of 9000 N required for laying work cannot be satisfied, and 700 N, which is the lowest condition among the tests, is also cleared. I couldn't. If the tearing force is 15 N (neck thickness D = 0.33 mm) or more, the ironing strength can be secured at least 900 N. However, if the tearing force exceeds 25 N (neck thickness D = 0.40 mm), the tearing force is reduced as described with reference to FIG. In other words, the neck thickness D is preferably 0.33 to 0.40 mm.

  FIG. 4 (B) is an examination of the “ironing strength” of the optical fiber cable shown in FIG. 1 (B). It should be noted that the change in “tear force” and the “scoring resistance” when the neck thickness D was constant at 0.4 mm and the notch angle α was varied were measured. As a result, it has been found that by providing a notch in the neck, the tearing force is reduced and the tearability is improved, but the ironing strength is greatly reduced, and the ironing strength is dependent on the angle α of the notch. As a result, if the notch angle α is less than 60 °, the ironing strength may not be able to clear 900 N, and the notch angle α needs to be 60 ° or more.

It is a figure explaining the outline of the present invention. It is a figure explaining the tearability of the main-body part and support line part of the optical fiber cable of this invention. It is a figure explaining the measuring method of the ironing strength of a cable. It is a figure explaining the ironing strength of the optical fiber cable of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main-body part, 2 ... Support line part, 3 ... Neck part, 4 ... Optical fiber core wire, 5 ... Tension member, 6 ... Main-body part jacket, 7 ... Rupture notch, 8 ... Support line, 9 ... Support line part Outer jacket, 10 ... notch.

Claims (3)

  A self-supporting optical fiber cable in which a main body part and a support wire part are connected and integrated by a neck part. The main body part has four or more optical fiber cores arranged in two stages and tensions on both sides in the arrangement direction. An optical fiber cable comprising a member and a single low-density polyethylene covered together with the neck, wherein the neck has a thickness of 0.33 mm to 0.40 mm.   2. The optical fiber cable according to claim 1, wherein a thickness of the neck portion is 0.40 mm, and a notch having an angle of 60 ° or more is formed.   The optical fiber cable according to claim 1 or 2, wherein the optical fiber core is provided with a protective coating having a coating outer diameter of 0.50 mm.

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