JP2967951B2 - Manufacturing method of optical fiber cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic spacer in which an optical fiber tape core is housed inside a plastic spacer extruded into a substantially U-shaped cross section, and a plurality of the spacers are arranged around a tension member. The present invention relates to a method for manufacturing an assembled optical fiber cable.

[0002]

2. Description of the Related Art A plurality of optical fiber cores are housed inside a plastic spacer having a cross section substantially extruded into a U-shape, and the spacers are assembled around a tension member. An optical fiber cable subjected to the above method is disclosed in, for example, JP-A-55-45087. The optical fiber cable of such a structure is compared with cables of other structures.
Although it is advantageous for increasing the number of cores and reducing the diameter, there is a problem that manufacturing is very difficult.

Conventional techniques for forming a tape spacer and assembling a tape spacer and an optical fiber in a tandem manner in an assembling step include, for example, JP-A-54-106249 and JP-A-56-1.
No. 9003 is disclosed. However, the prior art relating to the above manufacturing technique shows a method of manufacturing an optical fiber cable having a tape spacer structure in which a tape is formed into a spacer, and an extruded plastic spacer according to the present invention is used. Not something. JP 54-10624
The method disclosed in No. 9 shows a method in which a tape is formed into a U-shape in a state in which an optical fiber core is housed, and the tape is assembled around a tension member. 3 shows a method of assembling a tape spacer and an optical fiber core after molding using an assembling die.

[0004]

FIG. 2 is a cross-sectional view of an optical fiber cable to which the manufacturing method of the present invention is applied.
In the drawings, reference numeral 1 denotes a tension member, and 2 denotes a plastic spacer whose inside of a cross section is substantially extruded in a U-shape. A plurality of optical fiber ribbons 3 are accommodated in the groove 21 in a stacked state.
A tape winding layer is provided on the outer periphery of the plastic spacer 2 accommodating the optical fiber ribbon 3, and a plastic sheath 5 of vinyl chloride, polyethylene or the like is provided thereon. The outer shape of the plastic spacer 2 includes all shapes other than a circular shape such as a U-shaped cross section.

[0005] In the above-mentioned optical fiber cable, the outer shape of the spacer is not circular but has a U shape.
The spacers must always be assembled around the tension member without twisting. Therefore, the outermost optical fiber ribbon is always on the outside, and the innermost optical fiber ribbon is always on the inside. As a result, the twisting ratio varies depending on the position of the tape core wire in the spacer, and a difference occurs in the length of the optical fiber tape core wire in the cable. For this reason, in order to prevent the longitudinal strain from remaining in the optical fiber core in the manufactured cable, the length of the optical fiber tape core to be assembled is changed according to the difference in the twisting ratio. This is a problem in manufacturing the optical fiber cable having this structure.

In the case of a cable having a normal unit structure (a cable in which an optical fiber ribbon is accommodated in a U-shaped groove of a spacer corresponds to a unit in a cable having this structure), a unit is manufactured (in a cable having this structure, a spacer of a spacer is used). The storage of the shape in the groove) and the assembly of the units are performed in separate steps, but there is a problem that the above method cannot be applied to the cable having the present structure. In other words, if it is a separate process, it is necessary to make a twist difference according to the position of the optical fiber ribbon at the time of manufacturing the unit, but it is difficult to control the twist difference at the time of unitization, for example, Even if the set length of the tape core can be made different by changing the supply tension of the wire, etc., the twist ratio is increased in the straight part of the pass line (that is, the tape core has a long tape length). Occurs, which adversely affects the transmission characteristics (the meandering may be completely recovered at the time of unit assembly, but is not completely recovered due to friction between the tape cores and the like).

As described above, there is an assembling method in which a set of spacers and a set of optical fiber ribbons are tandemly set on the same line (Japanese Patent Application Laid-Open Nos. 54-106249 and 56-1).
9003). These are all methods of assembling an optical fiber cable having a tape spacer, and the former shows a method of storing an optical fiber core wire in a tape spacer formed into a U shape, and then assembling it around a tension member. Shows a method of assembling optical fiber cores at the bottom of the tape spacer immediately after passing through the assembling die. Both differ in that the location for storing the optical fiber core is before and immediately after the collective die, but in both cases the tape spacer and the optical fiber core are simultaneously placed around the tension member using one collective die. The arrangement is common.

In the structure of the optical fiber cable shown in FIG.
In the cable using the tape spacer as described above instead of the extruded plastic spacer, by using the assembling method shown in the above-mentioned JP-A-54-106249 and JP-A-56-19003, It is possible to create a tape length difference according to the twisting rate of each optical fiber tape core when assembling. Before and after the assembly die, the optical fiber ribbons touch and interact with each other, but the tape spacer is made of a material that can be easily deformed (because it must be molded into the tape spacer during assembly). The effect of the tape spacer on the tape core wire is small.Rather, each tape is moved so that it follows the movement of the tape core wire and moves together, resulting in a twisting difference according to the twist pitch and radius immediately after the gathering point. The core wire is naturally guided to the collective dice.

On the other hand, as shown in FIG. 2, in an optical fiber cable having a structure using an extruded plastic spacer, which is the object of the present invention, when the above-mentioned assembling method is used, since the rigidity of the spacer is high, an assembling die is required. To affect the optical fiber ribbon immediately after the twist pitch,
There is a problem in that the optical fiber ribbons are prevented from being assembled so as to have a twist difference corresponding to the twist radius. In other words, when the optical fiber ribbon and the spacer come into contact with each other just before the collecting die, the tape cores and the spacers have slightly different linear speeds guided to the collecting die due to the difference in the twisting ratio. And the spacers interact with each other to prevent each other from moving. Also, when assembling the optical fiber ribbon while assembling the spacers with the same assembling die, before the spacer is completely disposed around the tension member, that is, before the spacer is wound around the tension member and fixed. The tape cores are assembled in the spacer. Further, since there is a clearance between the assembly die and the assembled spacer, the spacer can move to some extent immediately after the assembly die. Therefore, immediately after the tape core and the spacer are gathered, if the spacer moves or tries to drop to the most stable position in the structure, or if disturbance such as fluctuation in tension of the spacer supply occurs, the spacer is already Residual strain applied to the tape cores gathered in the line changes, making it difficult to obtain stable characteristics.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a cable having a structure in which a spacer for accommodating an optical fiber ribbon is extruded substantially in the inside of a cross section and assembled around a tension member. In the present invention, there is provided a manufacturing method for realizing a highly reliable optical fiber cable with less distortion remaining in the optical fiber ribbon after manufacturing, and the feature is that the spacer is provided around a tension member by a first collective die. The bottom portion is brought into contact with the tension member to be assembled and integrated, and then the optical fiber ribbon is assembled in a tandem groove in the U-shaped groove of the spacer by the second assembly die.

[0011]

DETAILED DESCRIPTION FIG. 1 is an explanatory view of the embodiment of the method of the present invention, FIG. (B) is a side view of an essential part, FIG. (B) is X ₁ -X ₁ cross-sectional view of (i) Figure , FIG. (c) is a X ₂ -X ₂ cross-sectional view of (a) and FIG. The tension member 1 unwound from a supply device (not shown) is inserted into a first assembling die 11 and has a plastic spacer 2 around which the inside of a cross section is substantially extruded in a U-shape. A plurality of them are twisted and assembled by bringing their bottoms into contact with the tension member 1 to form the structure shown in FIG. After passing through the first collective die 11, the tension member 1 and the spacer 2 are integrated as shown in FIG. 1 (b), and then introduced into the second collective die 12, where the second collective die 12 At 12, a plurality of optical fiber ribbons 3 are stacked and assembled in the U-shaped groove 21 of each spacer 2 to obtain the structure shown in FIG. An optical fiber cable as shown in FIG. 2 is formed by applying a tape winding layer and a plastic sheath on the outer periphery of the spacer 2 thus formed. In the above,
It is preferable that the distance between the first collective die 11 and the second collective die 12 is equal to or more than one pitch of the twist pitch of the spacer 2 if possible. Any distance may be used as long as the spacer and the tension member are integrated.

[0012]

In the manufacturing method of the present invention described above, since the assembly of the spacer and the optical fiber ribbon is performed in tandem using another assembly die, the second assembly die portion for assembling the optical fiber ribbon is assembled. Since each tape core is introduced spontaneously without being affected by the spacer according to the difference in twisting ratio, it is possible to reduce the residual strain of the tape core caused by the difference in twisting ratio. Become. If the residual strain caused by the difference in the twisting ratio is large, the optical fiber ribbon located above the groove is elongated, and the tape ribbon located at the bottom of the groove is subjected to compressive strain. In this case, in terms of transmission characteristics, the loss increases due to the occurrence of microbending, and in terms of mechanical reliability, there is a problem that the breaking life of the optical fiber is short, but using the manufacturing method of the present invention Thereby, the above problem is improved.

[0013]

As described above, according to the method for manufacturing an optical fiber cable of the present invention, it is possible to reduce the residual strain of the tape core caused by the difference in the twisting ratio of each optical fiber tape. Thus, an optical fiber cable with low loss and high mechanical reliability can be realized.

[Brief description of the drawings]

FIG. 1 (b) is an explanatory view of a main part of the embodiment of the method of the present invention, FIG. 1 (b) is X ₁ -X ₁ cross-sectional view of (b), and FIG. 1
FIG. 3C is a cross-sectional view taken along the line X ₂ -X _{2 in} FIG.

FIG. 2 is a cross-sectional view of an optical fiber cable to which the manufacturing method of the present invention is applied.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 tension member 2 plastic spacer 3 optical fiber ribbon 11 first assembly die 12 second assembly die

Continuing on the front page (72) Inventor Masaichi Watanabe 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shigeru Tomita 1-6-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone (56) References JP-A-55-124111 (JP, A) JP-A-56-19003 (JP, A) JP-A-54-106249 (JP, A) JP-A-56-36609 (JP, A A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G02B 6/44

Claims (1)

(57) [Claims] 1. A plurality of plastic spacers having a cross section substantially extruded in a substantially U-shape by bringing a first collecting die into contact with the periphery of a tension member at the bottom of the spacer to integrate the plastic spacers. A method for producing an optical fiber cable, comprising: assembling optical fiber ribbons in a U-shaped groove of a spacer by a second collecting die in tandem.