JP2970669B1 - Optical cable manufacturing method - Google Patents

Abstract

An object of the present invention is to provide an optical cable manufacturing method capable of easily and inexpensively manufacturing an optical cable having good retrievability of an optical fiber after laying, wherein an inverted portion can be distinguished from the outside of a jacket. A plurality of optical fibers (6) are provided around a center member (2).
Are assembled in an SZ twisted state, and the optical fiber 6
In the method of manufacturing an optical cable in which the periphery of the optical fiber 6 is covered with the jacket 10, the ferromagnetic member 8 is positioned along the SZ locus formed by any of the optical fibers 6 so as to be located near the inner peripheral surface of the jacket 10. Deploy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical cable to be laid underground, on land, aerial or undersea, and more particularly, to a method in which a plurality of optical fibers are assembled in an SZ twisted state and the periphery of each optical fiber is outside. The present invention relates to a method for manufacturing an optical cable covered with a cover.

[0002]

2. Description of the Related Art Hitherto, there has been known an optical cable in which a plurality of optical fibers are assembled in an SZ twisted state around a central member having a built-in strength member, and each optical fiber is covered with a jacket. . Such an optical cable is laid underground, on land, aerial or on the sea floor, but once the optical cable is laid, a part of the jacket is removed or cut off in the middle of the optical cable, and the optical cable is cut. In some cases, it is necessary to take out a part of the optical fiber contained in the optical fiber and branch it (so-called middle post-branch).

Here, in an optical cable having a plurality of optical fibers extending in an SZ shape, an optical cable (center member)
The length of each optical fiber is larger than the length of the optical fiber. Therefore,
If the jacket near the reversal part of the SZ locus formed by the optical fiber (the part where the optical fiber reverses from S twist to Z twist or from Z twist to S twist) is removed, the optical fiber is pulled excessively. It can be taken out smoothly from the optical cable without any trouble. In view of this point, if the reversal part of the SZ trajectory formed by the optical fiber can be determined from the outside of the jacket of the optical cable, the workability when branching after laying the cable is improved.

[0004] Techniques related to the above are disclosed in US Pat. No. 4,828,352 and US Pat.
No. 9,966 is known.
The conventional optical cables described in these documents are obtained by assembling a plurality of optical fibers (optical fiber cores or pipe cores) in an SZ twist around a central member. The periphery of each optical fiber is covered with a jacket formed of a synthetic resin or the like. The outer jacket is provided with a reversing portion display mark such as a symbol or a character at a position corresponding to the reversing portion of the SZ locus formed by each optical fiber.

[0005] This optical cable is manufactured according to the following procedure. That is, when the process from the twisting of the optical fiber to the process of forming the jacket is performed in one manufacturing line, the display marker forming device (core marker apparatus) is arranged downstream of the jacket cooling water tank, and From the plurality of lay plates used for twisting the optical fiber around the member, a signal indicating the reversal direction of the fold plate located at the most downstream side is extracted. Then, based on this signal, the supply length of the central member, and the predetermined offset length, when it is determined that the reversing section has reached below the display mark forming apparatus, the reversing section display mark is displayed by the display mark forming apparatus. Formed on the jacket.

In the case where the optical fiber twisting step and the jacket forming step are divided, in the optical fiber twisting step, the same method as in the case where an optical cable is manufactured on one manufacturing line as described above. Then, a color tape or a metal tape indicating the position of the inversion section is pasted on the holding tape wound around the outer periphery of each optical fiber. In the step of forming the outer cover, before the outer cover is extruded, the color tape or the like attached to the presser winding tape is detected by a color sensor, a metal sensor, or the like, and is extruded based on the detection signal. A reversal portion indicating mark is formed on the outer cover.

[0007]

However, the conventional optical cable manufacturing method has the following problems.

In other words, the conventional method of manufacturing an optical cable uses a color tape or the like or a reverse tape attached to a holding tape to indicate the position of a reversing portion before providing a jacket around the optical fiber. Based on the operation of the plate and the like, the position of the reversing portion is detected, and then a reversing portion indicating mark is put on the extruded jacket. For this reason, in an optical cable manufactured by the conventional method, unless the reversing portion indication mark is provided,
Once the jacket is provided, it is practically impossible to determine the position of the reversing portion inside the jacket from the outside of the jacket. In addition, when manufacturing an optical cable, equipment for attaching a color tape or the like is required, so that the cost required for the equipment for manufacturing the optical cable increases, and the manufacturing cost of the optical cable also increases.

[0009] Further, the inversion portion display mark attached to the outer cover for indicating the position of the inversion portion may disappear after the optical cable is laid. Also in this case, it is impossible to detect the position of the reversing portion from the outside of the jacket unless the jacket is completely removed. Therefore, if the inversion mark is peeled off on the jacket, it is extremely difficult to determine the position of the inversion section inside the jacket from the outside of the jacket. Remarkably deteriorates.

Accordingly, the present invention provides a method of manufacturing an optical cable that can easily and inexpensively manufacture an optical cable having good take-out of an optical fiber after laying, in which the inverted portion can be determined from the outside of the jacket. The purpose is to:

[0011]

According to a first aspect of the present invention, there is provided a method for manufacturing an optical cable, comprising: a plurality of optical fibers in an SZ twisted state around a central member;
In a method of manufacturing an optical cable in which the periphery of an optical fiber is covered with a jacket, a ferromagnetic member is arranged along the SZ locus formed by one of the optical fibers so as to be located near the inner peripheral surface of the jacket. It is characterized by the following.

This method of manufacturing an optical cable is for manufacturing an optical cable in which a plurality of optical fibers are assembled in an SZ twist state around a central member. In such an optical cable, the inversion portion of the SZ locus formed by the optical fiber is located on the same circumference around the central axis of the optical cable (note that “optical fiber” is an optical fiber core wire,
Tape core, tape core laminate, pipe core, etc. are used as a general term.) Based on this point, in this method of manufacturing an optical cable, the ferromagnetic member is arranged along the SZ locus formed by any of the optical fibers. Further, the ferromagnetic member is arranged near the inner peripheral surface of the jacket.

Thus, in the optical cable manufactured by the method for manufacturing an optical cable, the position of the inverted portion of each optical fiber can be determined by detecting the inverted portion of the ferromagnetic member. Also, the reversal part of the ferromagnetic member is
Using a metal sensor or the like, it is possible to detect easily and reliably from the outside of the jacket. That is, according to the method for manufacturing an optical cable of the present invention, it is possible to easily and inexpensively manufacture an optical cable capable of determining the inverted portion of the SZ locus formed by each optical fiber from the outside of the jacket.

In this case, it is preferable to use an iron wire as the ferromagnetic member. That is, iron wire is inexpensive and excellent in handleability among ferromagnetic member materials. Therefore, the optical cable according to the present invention can be easily and inexpensively manufactured.

It is preferable that a reversal portion of the SZ locus formed by the ferromagnetic member is detected via the outer cover, and a reversal portion indicating mark is provided at a position corresponding to the reversal portion of the outer cover. Thereby, it is possible to put a reversal portion display mark on the jacket in a state in which the position exactly corresponds to the position of the reversal portion of the SZ locus formed by the optical fiber. Further, after the completion of the optical cable, it is possible to inspect whether or not the inversion mark is exactly corresponding to the position of the inversion of the optical fiber. Further, since it is not necessary to apply a marking for indicating the reversal part of the optical fiber before providing the jacket, when the jacket is provided, the marking material (paint, various tapes, etc.) is mixed into the material of the jacket. Can be prevented.

In this case, when detecting the reversal part of the ferromagnetic member, it is preferable to use a plurality of metal sensors having coils and detect the reversal part based on the induced current generated in each coil. Thus, the inverted portion of the ferromagnetic member can be easily and reliably detected from the outside of the jacket.

When the optical fibers are assembled in an SZ twisted state around the center member and the ferromagnetic members are arranged, the following method may be employed.

That is, a multi-groove spacer in which a plurality of SZ-shaped spiral grooves are formed on the outer periphery and a ferromagnetic member is fixed so as to be located between any two spiral grooves as a central member. It is preferable to use a multi-groove spacer in which a plurality of SZ-shaped spiral grooves are formed on the outer periphery as the central member, and it is preferable to accommodate the ferromagnetic member in any of the spiral grooves.

Furthermore, when a plurality of optical fiber units including optical fibers are used, the optical fiber units are SZ-twisted around the central member and assembled, and when the optical fiber units are assembled around the central member, ferromagnetic Preferably, the member is supplied along any one of the optical fiber units, and a plurality of optical fiber units including the optical fiber are used, and the optical fiber unit is SZ-twisted around the central member to be aggregated. It is preferable that the ferromagnetic member is fixed to any of the units in advance. In this case, the optical fiber unit is preferably made of a single-groove spacer accommodating the optical fiber, and the optical fiber unit is preferably a loose tube.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for manufacturing an optical cable according to the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 is a sectional view showing an optical cable manufactured by applying the first embodiment of the method for manufacturing an optical cable according to the present invention. In the center of the optical cable 1 shown in FIG. 1, a long cylindrical member 2 serving as a central member is arranged. This cylindrical member 2 is an LDP
It is made of synthetic resin such as E resin
Having an outer diameter of In the center of the columnar member 2, one steel stranded wire 3 is embedded. The steel stranded wire 3 is one in which seven steel wires having a diameter of 2 mm are stranded together. Fifteen optical fiber units 4 are twisted in an SZ shape on the outer periphery of the cylindrical member 2 (see FIG. 3). The SZ twist pitch of each optical fiber unit 4 (twice the length between adjacent inversion portions) is 900 mm, and the SZ inversion angle φ is 275 °.

Here, as shown in FIG. 1, one of the fifteen optical fiber units 4 has one optical fiber unit 4.
(The optical fiber unit 4F) includes a ferromagnetic member 8
Has been fixed. The optical fiber unit 4F includes, as shown in FIG.
(Optical fiber). The single groove spacer 5F is manufactured as one straight long member by extruding PBT resin or the like.
It has a substantially U-shaped cross section. Bottom 5a of single groove spacer 5F
The pair of side portions 5b define one fiber housing portion 5c capable of housing various optical fibers such as an optical fiber core, a pipe core, and a tape core.

Also, a pair of side portions 5b of the single groove spacer 5F
The ferromagnetic member 8 is embedded in the upper end of the side wall 5b on one side (in this case, the left side in FIG. 2). In this optical cable 1, as the ferromagnetic member 8,
A 0.4 mm iron wire (ferromagnetic wire) is used. Iron wire is inexpensive among ferromagnetic materials and has excellent handleability. Therefore, the optical cable according to the present invention is
It can be manufactured easily and inexpensively. As the ferromagnetic member 8, a nickel wire, a cobalt wire, or the like may be used instead of the iron wire. When embedding the ferromagnetic member 8 in the single groove spacer 5F, the ferromagnetic member 8 may be extruded simultaneously with the melted PBT resin or the like. In addition. The dimensions of the single groove spacer 5 are Bu = 6.0 mm, Bu = 4.0 mm,
Bl = 5.0 mm, bl = 3.5 mm, D = 5.0 m
m and d = 4.5 mm.

The tape core laminate 6 is formed by laminating ten eight-core tape cores. Tape cored laminate 6
Are housed in the fiber housing portion 5c of the single groove spacer 5F. Then, a holding tape 7 such as a nonwoven fabric is wound around the single groove spacer 5F in which the tape core laminate 6 is accommodated. Thereby, the single groove spacer 5F and the tape core laminate 6 are unitized.

The optical fiber unit 4 other than the optical fiber unit 4F is a unit in which a single groove spacer 5 and a tape core laminate 6 are unitized. The single groove spacer 5 is the same as the single groove spacer 5F except that the ferromagnetic member 8 is not embedded in the side portion 5b. By twisting each optical fiber unit 4 (4F) around the central member 2 in an SZ shape, each tape core laminate 6 as an optical fiber is assembled around the cylindrical member 2 in an SZ twisted state. Become.

As shown in FIG. 1, a holding tape 9 made of a nonwoven fabric or the like is wound without any gap around each optical fiber unit 4 twisted in an SZ shape on the outer peripheral surface of the cylindrical member 2. Then, around the holding tape 9,
A jacket 10 having an outer diameter of 41 mm formed of low-density polyethylene is provided. Thereby, the optical cable 1
Inside is protected. Further, as shown in FIG. 1, one tear string 11 is built in the outer cover 10.

In the inside of the jacket 10 of the optical cable 1, FIG.
As shown in (2), each of the optical fiber units 4 and 4F (tape fiber laminate 6) forms a locus extending in an SZ shape (hereinafter, referred to as “SZ locus”). The SZ locus includes a portion where the optical fiber units 4 and 4F are inverted from S twist to Z twist or from Z twist to S twist (hereinafter, referred to as “inversion portion R”). Then, as shown in FIG. 3, the inversion portion R of the SZ locus formed by each of the optical fiber units 4 and 4F.
Are located on the same circumference around the central axis of the optical cable 1.

Similarly, inside the jacket 10 of the optical cable 1, as shown in FIG. 3, the ferromagnetic member 8 forms an SZ locus along the tape core laminate 6 included in the optical fiber unit 4F. I have. The SZ locus formed by the ferromagnetic member 8 also includes the inversion portion RF, and the inversion portion RF of the ferromagnetic material 8
Are also located on the same circumference as the inversion portion R of each of the optical fiber units 4 and 4F. The ferromagnetic material 8 is provided on one side 5b of the single groove spacer 5F included in the optical fiber unit 4F.
1, it is located near the inner peripheral surface of the outer casing 10 as shown in FIG. 1 when disposed around the center member 2.

Therefore, the inverted portion RF of the ferromagnetic member 8 can be easily and reliably detected from the outside of the jacket 10 using a metal sensor or the like. Then, by detecting the inversion portion RF of the ferromagnetic member 8, the position of the inversion portion R of each of the optical fiber units 4, 4F (tape core laminate 6) can be determined. That is, in the optical cable 1, it is possible to easily determine the position of the inversion portion R (RF) regardless of whether or not there is a display indicating the position of the inversion portion R of each of the optical fiber units 4 and 4F. As a result, the work efficiency at the time of taking out and branching the optical fiber (tape core laminate 6) by removing a part of the jacket at the intermediate portion of the optical cable 1 is improved. Thus, this optical cable 1
Since an optimum location for branching can be easily found and a flexible branching operation can be performed, the optical cable is suitable for laying in a place where the extra length of the optical cable must be shortened (for example, underground).

Further, as shown in FIG. 4, on the jacket 10 of the optical cable 1, a reversing portion display mark M indicating a position corresponding to the reversing portion R of the SZ locus formed by the ferromagnetic member 8 is provided. Have been. In the optical cable 1, the letter “R” of the alphabet is marked on the outer cover 10 using a printing device or the like as the inversion portion display mark M. By providing the reversing portion display mark M in this way, when removing and branching the tape core laminate 6 (optical fiber) by removing a part of the jacket 10 at the intermediate portion of the optical cable 1, work is difficult. The most appropriate position of the reversing portion R can be more easily determined, and the working efficiency is extremely improved. It is preferable that the inversion portion display mark M be provided over the entire circumference of a concentric circle centered on the central axis of the optical cable 1 in consideration of the distinguishability at the time of work.

As shown in FIG. 5, a sign (symbol) may be used as the inverted portion display mark M. In the example shown in FIG. 5, an elongated metal tape 12 (for example, a copper tape having a length of about 30 mm and a width of about 5 mm) is provided as a reversal part display mark M at a position corresponding to the reversal part R of the jacket 10. 1 is attached so as to be orthogonal to the longitudinal direction. Even if such a configuration is adopted, the position of the reversing portion R can be determined very easily from the outside of the jacket 10 of the optical cable 1. At the time of removal, it is possible to easily determine the position of the reversal portion R that is most appropriate for the operation, so that the operation efficiency is extremely improved. The shape and the like of the inverted portion display mark M are not limited at all, and any characters, symbols, and signs can be used.

Next, a first embodiment of the method for manufacturing an optical cable according to the present invention will be described in detail.

When the optical cable 1 is manufactured, first, the optical fiber units 4 and 4F are twisted around the cylindrical member 2 using the optical fiber twisting line 50 shown in FIG. In this case, the cylindrical member 2 as the center member
Is wound on a core winding reel 51. The optical fiber units 4 and 4F are wound around the optical fiber unit winding reel 52 in advance. And the core winding reel 51
And one optical fiber unit 4 and 4F (in this case, 15) from the optical fiber unit winding reel 52 to the reverse perforated panel group 53.

Each of the optical fiber units 4 and 4F is gradually twisted into an SZ shape by each of the reversing eye plates 54 that rotate independently while changing the rotation direction within a predetermined reversing angle. A thread or the like for temporarily fixing the optical fiber units 4 and 4F is wound around the optical fiber units 4 and 4F twisted around the columnar member 2 by the holding-winding device 55, and the holding winding is performed. The tape 8 is wound without any gap. Thereby, the respective tape core laminates 6 included in the respective optical fiber units 4 and 4F assemble around the cylindrical member 2 in an SZ twisted state. The ferromagnetic member 8 included in the optical fiber unit 4F is arranged in an SZ twisted state along the tape core laminate 6 included in the optical fiber unit 4F. The semi-finished product H1 with the holding tape 8 wound thereon is wound on a take-up reel 56.

When the twisting of the optical fiber units 4 and 4F with respect to the cylindrical member 2 is completed, the jacket 10 is provided on the semifinished product H1 by using the jacket forming line 60 shown in FIG. In this case, as shown in FIG.
Supplies the semi-finished product H1 to the jacket extruder 61.
From the jacket extrusion device 61, the jacket 10 is placed around the semi-finished product H1.
Is extruded. The semi-finished product is introduced into the jacket cooling water tank 62, whereby the jacket 10 is cooled and solidified.

When the jacket 10 is solidified, the ferromagnetic material 8 buried at the upper end of the side portion 5b of the single groove spacer 5F included in the optical fiber unit 4F is interposed between the ferromagnetic body 8 and the holding tape 8 via the holding tape 8. It will be located near the inner peripheral surface (see FIG. 1).
reference). The semi-finished product H2 in a state where the jacket 10 is solidified passes through a metal detection device 63 arranged downstream of the jacket cooling water tank 62. The metal detecting device 63 can detect the position of the reversal portion RF of the ferromagnetic member 8 via the jacket 10.

A method of detecting the reversal portion RF of the ferromagnetic member 8 by the metal detection device 63 will be described with reference to FIGS. The metal detecting device 63 includes a metal sensor 65 having a coil 64 (for example, EX-42 manufactured by Keyence Corporation).
2) (for example, 12), and each coil 64
The inversion unit RF is detected based on the induced current generated in the inversion unit. As shown in FIG. 8, each metal sensor 65 is disposed on a concentric circle that covers the periphery of the jacket 10,
4 faces one surface of the jacket 10. FIG. 8 shows only three metal sensors 65a, 65b, and 65c among the twelve metal sensors 65. As shown in FIG. 7, the metal detection device 63 is connected to a control computer 66. When an induced current is generated in the coil 64 of each metal sensor 65, the metal detection device 63 sends a predetermined detection signal to the control computer 66. A signal is sent.

As shown in FIG. 8, it is assumed that the ferromagnetic member 8 has passed near the metal sensor 65a at a certain time t1.
In this case, an induced current is generated in the coil 64 of the metal sensor 65a as shown in FIG. 9, and a detection signal is sent from the metal sensor 65a to the control computer 66. Since the ferromagnetic member 8 extends in an SZ shape along any one of the tape core laminates 6, when the semi-finished product H2 advances, it passes near the metal sensor 65b adjacent to the metal sensor 65a. (Time t2), and further pass near the metal sensor 65c adjacent to the metal sensor 65b (time t2).
3).

The ferromagnetic member 8 extending in the SZ shape is
It has an inversion part RF. Therefore, for example, as shown in FIG. 8, the ferromagnetic member 8 once passes through the vicinity of the metal sensor 65c and then again passes through the vicinity of the metal sensor 65c until a predetermined time T (see FIG. 9) elapses. (Time t
4). That is, in the example shown in FIG. 8, the reversal part RF of the ferromagnetic member 8 passes near the metal sensor 65c at a time tm intermediate between the times t3 and t4. This makes it possible to easily and reliably detect the reversal portion RF of the ferromagnetic member 8 from outside the jacket 10 based on the detection signal emitted from each metal sensor 65 of the metal detection device 63.

The control computer 64 is connected to a display mark forming device 67 which is arranged on the downstream side of the metal detecting device 63 and is capable of arranging the inversion portion display mark M on the jacket 10. As shown in FIG. 4, when a character is used as the inversion portion display mark M, a printing device (for example, an inkjet manufactured by Imaju) is used as the display mark forming device 67. In this case, it is preferable to arrange three printing devices in order to provide the reversal portion display mark M on the entire circumference of the jacket 10. In addition, as shown in FIG. 5, when a mark using a metal tape is provided as the reversal portion display mark M, a tape sticking device may be used as the display mark forming device 67.

The control computer 64 controls the metal detector 6
A predetermined operation is performed on the basis of the detection signal received from the third ferromagnetic member 8, and the inverted portion RF of the ferromagnetic member 8
Find the timing of reaching below. That is, the control computer 66 transmits the metal detection device 63 (the metal sensor 6).
5), if an induced current is generated twice in the coil 64 included in any one of the metal sensors 65 within a predetermined time T based on the detection signal (time t3 in FIG. 8).
And t4), a time tm intermediate between times (t3, t4) at which the induced current is generated in the one metal sensor 65 is obtained,
At this time tm, it is determined that the inverted portion RF of the ferromagnetic member 8 has passed through the metal detection device 63.

When the reversing part RF of the ferromagnetic member 8 reaches below the display mark forming device 67, the control computer 66 operates the display mark forming device 65. The display mark forming device 65 includes a cover 10 that covers the vicinity of the reversal portion RF (R).
A reversal portion display mark M (for example, the character “R”) is attached on the top. Thus, the optical cable 1 shown in FIGS. 1 and 4 or 5 is completed. The completed optical cable 1 is taken up on a take-up reel 68.

As described above, according to the method for manufacturing an optical cable according to the present invention, the SZ in which the optical fiber units 4 and 4F (the tape core laminate 6) are formed from the outside of the jacket 10 is formed.
It is possible to easily and inexpensively manufacture the optical cable 1 that can determine the reversal part R of the trajectory. Further, S formed by the optical fiber units 4 and 4F (tape core laminate 6)
In a state where the position corresponds to the inverted portion R of the Z trajectory, the inverted portion display mark M can be attached to the jacket 10. Further, after completion of the optical cable 1, it is possible to inspect whether or not the reversal portion indication mark M accurately corresponds to the position of the reversal portion R of the tape core laminate 6. In addition, the jacket 10
Therefore, it is not necessary to perform marking for indicating the reversal portion R before providing the marking, so that it is possible to prevent the marking material (paint, various tapes, etc.) from being mixed into the material of the jacket when the jacket is provided. .

In the first embodiment, after the outer jacket 10 is extruded and cooled, the inverted portion RF of the ferromagnetic member 8 is detected by the metal detector 63 via the outer jacket 10. Although the display mark M is provided, the present invention is not limited to this. That is, the optical cable 1 provided with the jacket 10 may be once wound up, and the reversal portion display mark M may be put on the jacket 10 by another line.

[Second Embodiment] FIG. 10 is a sectional view showing an optical cable manufactured by applying the second embodiment of the method for manufacturing an optical cable according to the present invention. The optical cable 20 shown in the figure has a plurality of (five) loose tubes 24 as an optical fiber unit. As shown in FIG.
A ferromagnetic member 28 is fixed to one of the five loose tubes 24 (referred to as a loose tube 24F). As shown in FIG. 11, the loose tube 24F includes a tube 25F (outer diameter 6.0 mm, inner diameter 4.5 mm) formed of polyethylene,
Tape core laminate 26 housed inside tube 25
(Optical fiber).

A ferromagnetic member 28 is embedded in the tube 25F. In this case, 0.
A 4 mm iron wire (ferromagnetic wire) is used. When embedding the ferromagnetic member 28 in the tube 25F, the ferromagnetic member 8 may be extruded simultaneously with the molten polyethylene resin or the like. The tape core laminate 26 is obtained by laminating ten eight-core ribbons. In addition, inside the tube 25, together with the tape core laminate 26,
Grease 27 serving as a cushioning material is filled. Loose tubes 24 other than loose tubes 24F
Is a unit of the tube 25 and the tape core laminate 26. The tube 25 is the same as the tube 25F except that the ferromagnetic member 28 is not embedded.

At the center of the optical cable 20, a long cylindrical member 22 (LDPE) serving as a central member is provided.
(Resin, 25 mm in diameter). Column member 2
Is embedded in the center of the steel wire. This steel stranded wire 23 is also formed by twisting seven steel wires each having a diameter of 2 mm.
It is a book. Fifteen loose tubes 24 are twisted in an SZ shape on the outer periphery of the cylindrical member 22. The SZ twist pitch of each loose tube 24 is 90
0 mm, and the SZ inversion angle φ is 275 °. A presser winding tape 29 is wound around each loose tube 24 without gaps. An outer diameter 4 made of low-density polyethylene is further formed around the holding tape 29.
A 1 mm jacket 21 is provided. In addition, this jacket 2
1 includes one tear string 21a.

When the optical cable 20 is manufactured, the loose tubes 24 and 24F may be twisted around the cylindrical member 22 using the optical fiber twisting line 50 shown in FIG. That is, the loose tubes 24 and 24F are wound around the optical fiber unit winding reel 52, and one cylindrical member 22 and a plurality of (15 in this case) loose tubes 24, 24F
Should be supplied.

Third Embodiment FIG. 12 is a sectional view showing an optical cable manufactured by applying a third embodiment of the method for manufacturing an optical cable according to the present invention. The optical cable 1A shown in the figure has a structure basically similar to that of the optical cable 1 shown in FIG. Optical cable 1A shown in FIG.
Means that a plurality of optical fiber units 4 (15
This is different from the optical cable 1 of FIG. 1 in that it does not have the optical fiber unit 4F to which the ferromagnetic member 8 is fixed.
In this optical cable 1A, each optical fiber unit 4
SZ twist is assembled around the cylindrical member 2. Then, the ferromagnetic member 8 </ b> A is arranged between any two optical fiber units 4. Ferromagnetic member 8A
Is a ferromagnetic wire (outer diameter 0.8 mm) in which a steel wire having an outer diameter 0.5 mm is coated with polyethylene. Thus, instead of fixing the ferromagnetic member to the optical fiber unit 4 (single groove spacer 5), the ferromagnetic member may be disposed between the two optical fiber units 4.

When the optical cable 1A is manufactured, the optical fiber unit 4 is twisted around the cylindrical member 2 using the optical fiber twisting line 50 shown in FIG.
Then, the ferromagnetic member 8A may be supplied along any one of the optical fiber units 4. In this case, a dedicated winding reel around which the ferromagnetic member 8A is wound is installed on the side of any one of the optical fiber unit winding reels 52, and the ferromagnetic member 8A is inverted together with the single optical fiber unit 4. It may be supplied to the eyelet group 53. Further, the ferromagnetic member 8A is temporarily fixed to a single groove spacer 5 included in any one of the optical fiber units 4 using a tape or the like, and such an optical fiber unit 4 is attached to the optical fiber unit winding reel 52. It may be wound and supplied to the inverting plate group 53.

[Fourth Embodiment] FIG. 13 is a sectional view showing an optical cable manufactured by applying the fourth embodiment of the method for manufacturing an optical cable according to the present invention. The optical cable 20A shown in the figure has basically the same structure as the optical cable 20 shown in FIG. The optical cable 20A shown in FIG.
5) Loose tube 2 having ferromagnetic member 8 fixed
It differs from the optical cable 20 of FIG. 10 in that it does not have the 4F. In this optical cable 20A, each loose tube 24
Are assembled around the cylindrical member 2 in an SZ twist. Then, the ferromagnetic member 28 </ b> A is arranged between any two optical fiber units 4. Ferromagnetic member 2
8A is a ferromagnetic wire (outer diameter 0.8 mm) in which a steel wire having an outer diameter 0.5 mm is coated with polyethylene. Thus, the ferromagnetic member is connected to the loose tube 24 (tube 2).
Instead of fixing to 5), it may be arranged between two loose tubes 24.

When the optical cable 1A is manufactured, the loose tube 24 is twisted around the cylindrical member 2 using the optical fiber twisting line 50 shown in FIG. Then, the ferromagnetic member 8A may be supplied along any one of the loose tubes 24. In this case, a dedicated winding reel around which the ferromagnetic member 28A is wound is installed on the side of any of the optical fiber unit winding reels 52, and the ferromagnetic member 28A is placed together with one loose tube 24 together with the reversing member. It may be supplied to the plate group 53. Further, the ferromagnetic member 28A is temporarily fixed to a tube 25 included in any one of the loose tubes 24 by using a tape or the like, and such a loose tube 24 is attached to the optical fiber unit winding reel 5.
2 and may be supplied to the reverse perforated panel group 53.

[Fifth Embodiment] FIG. 14 is a sectional view showing an optical cable manufactured by applying the fifth embodiment of the method for manufacturing an optical cable according to the present invention. The optical cable 30 shown in the figure uses a multi-groove spacer 32 (outer diameter 24 mm) made of HDPE resin as a central member. One steel stranded wire 33 is embedded in the center of the multi-groove spacer 32. This steel stranded wire 33 is obtained by twisting seven steel wires having a diameter of 2 mm into one. A plurality (10) of SZ-shaped spiral grooves 34 are provided on the outer periphery of the multi-groove spacer 32.
Is formed. The depth of each spiral groove 34 is 4.3 mm,
The top width (corresponding to bu in FIG. 2) is 4.2 mm, and the bottom width is
3.2 mm. Further, the SZ pitch of each spiral groove 34 is 700 mm, and the SZ inversion angle φ is 275 °.

A ferromagnetic member 38 is fixed to the multi-groove spacer 32 so as to be located between any two spiral grooves 34. That is, in the multi-groove spacer 32 in which a plurality of SZ-shaped spiral grooves 34 are formed on the outer periphery, the ribs 32a located between any two spiral grooves 34 also extend in the SZ shape. In the multi-groove spacer 32, one ferromagnetic member 38 is embedded in a rib 32a extending in an SZ shape. In the optical cable 30, a 0.4 mm iron wire (ferromagnetic wire) is used as the ferromagnetic member 38. As the ferromagnetic member 38, a nickel wire, a cobalt wire, or the like may be used instead of the iron wire.

Each spiral groove 34 is provided with one eight-core ribbon cable.
A zero-core laminated fiber core 36 (optical fiber) is accommodated therein. As a result, the tape core laminate 36
Gather in the spiral groove 34 of the multi-groove spacer 32 as a central member in an SZ twisted state. In addition, the ferromagnetic member 38
It extends along the SZ locus formed by one tape core laminate 6. A holding tape 35 such as a nonwoven fabric is wound around the multi-groove spacer 32 in which the tape core laminate 36 is accommodated in each spiral groove 34 without any gap. And
Around the presser winding tape 35, there is provided an outer cover 31 (outer diameter 29 mm) formed of low-density polyethylene and containing a tear string 331a. Ferromagnetic member 3
8 is buried (fixed) in the rib 32 a of the multi-groove spacer 32, and thus is located near the inner peripheral surface of the outer cover 31.

When manufacturing the optical cable 30,
The multi-groove spacer 32 manufactured by simultaneously extruding the ferromagnetic member 38 together with the melted HDPE resin or the like is used.
Each spiral groove 34 of the multi-groove spacer 32 accommodates the tape core laminate 6 (optical fiber). Then, using the jacket forming line 60 shown in FIG. 7, the jacket 31 may be provided around the multi-groove spacer 32 accommodating the tape core laminate 6.

Sixth Embodiment FIG. 15 is a sectional view showing an optical cable manufactured by applying a sixth embodiment of the method for manufacturing an optical cable according to the present invention. The optical cable 30A shown in the figure has basically the same structure as the optical cable 30 shown in FIG. The optical cable 30A shown in FIG. 15 differs from the optical cable 30 of FIG. 14 in that it includes a multi-groove spacer 32A to which the ferromagnetic member 38 is not fixed. In this optical cable 30A, the ferromagnetic member 38A
Are accommodated in any of the spiral grooves 34. The ferromagnetic member 38A is a ferromagnetic wire (0.8 mm outer diameter) in which a steel wire having an outer diameter of 0.5 mm is coated with polyethylene. Even in such a configuration, the ferromagnetic member 38A can
And extends along the SZ trajectory formed by one tape core laminate 6 (optical fiber).

When the optical cable 30A is manufactured, a general multi-groove spacer 32A incorporating a steel stranded wire 33 is used.
Is used. Then, each spiral groove 34 of the multi-groove spacer 32
Then, when accommodating the tape core laminate 6 (optical fiber), the ferromagnetic member 38A is accommodated in any one of the spiral grooves 34 together with the tape core laminate 6.

[0059]

According to the optical cable manufacturing method of the present invention, the following effects can be obtained. That is, by arranging the ferromagnetic member along the SZ locus formed by any one of the optical fibers so as to be located near the inner peripheral surface of the jacket, the reversing portion can be determined from the outside of the jacket. Thus, it is possible to realize a method of manufacturing an optical cable that can easily and inexpensively manufacture an optical cable having good take-out of an optical fiber after installation.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical cable manufactured according to a first embodiment of an optical cable manufacturing method according to the present invention.

FIG. 2 is a sectional view showing an optical fiber unit included in the optical cable of FIG.

FIG. 3 is a plan view showing the inside of a jacket provided on the optical cable of FIG. 1;

FIG. 4 is a plan view for explaining a reversing portion display mark provided on the optical cable of FIG. 1;

FIG. 5 is a plan view illustrating another embodiment of the inversion portion display mark.

FIG. 6 is a schematic diagram showing an optical cable production line for producing the optical cable of FIG.

FIG. 7 is a schematic diagram showing an optical cable production line for producing the optical cable of FIG.

FIG. 8 is a schematic diagram for explaining a method of detecting a reversal portion of the ferromagnetic member.

FIG. 9 is a chart for explaining a method of detecting a reversal portion of the ferromagnetic member.

FIG. 10 is a sectional view showing an optical cable manufactured by a second embodiment of the method for manufacturing an optical cable according to the present invention.

11 is a sectional view showing an optical fiber unit included in the optical cable of FIG.

FIG. 12 is a sectional view showing an optical cable manufactured by a third embodiment of the method for manufacturing an optical cable according to the present invention.

FIG. 13 is a sectional view showing an optical cable manufactured according to a fourth embodiment of the method for manufacturing an optical cable according to the present invention.

FIG. 14 is a sectional view showing an optical cable manufactured according to a fifth embodiment of the method for manufacturing an optical cable according to the present invention.

FIG. 15 is a sectional view showing an optical cable manufactured according to a sixth embodiment of the method for manufacturing an optical cable according to the present invention.

[Explanation of symbols]

1, 1A, 20, 20A, 30, 30A ... optical cable,
2,22: cylindrical member (center member), 3, 23, 33: copper stranded wire (tensile member), 4, 4F: optical fiber unit,
5, 5F: single groove spacer; 6, 26, 36: tape core laminate (optical fiber); 7, 9, 29, 35: holding tape, 8, 28, 28A, 38, 38A: ferromagnetic member;
10, 21, 31 ... jacket, 24, 24F ... loose tube (optical fiber unit), 25, 25F ... tube,
32, 32A: multi-groove spacer (center member) M: reversing part,
R, RF: reversal unit, 63: metal detector, 64: coil, 65, 65a, 65b, 65c: metal sensor.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tadaki Haruki 1-chome, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (56) References JP-A-11-133279 (JP, A) JP-A-4-59639 (JP, A) JP-A-1-173509 (JP, A) JP-A-8-227033 (JP, A) JP-B-56-35842 (JP, B2) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G02B 6/44

Claims (10)

(57) [Claims] 1. A plurality of optical fibers are provided around a central member.
In a method for manufacturing an optical cable, wherein the optical fiber is covered with a jacket while being gathered in a Z-twisted state, the inner peripheral surface of the jacket is arranged along an SZ locus formed by any of the optical fibers. A method for manufacturing an optical cable, comprising: arranging a ferromagnetic member so as to be located in the vicinity. 2. The method according to claim 1, wherein an iron wire is used as the ferromagnetic member. 3. A reversal portion of the SZ locus formed by the ferromagnetic member is detected via the outer cover, and a reversal portion indication mark is provided at a position corresponding to the reverse portion of the outer cover. The method for manufacturing an optical cable according to claim 1. 4. The method according to claim 1, wherein a plurality of metal sensors having coils are used to detect the inversion of the ferromagnetic member, and the inversion is detected based on an induced current generated in each of the coils. The method for manufacturing an optical cable according to claim 3. 5. A plurality of SZ-shaped spiral grooves are formed on the outer periphery as the central member, and the ferromagnetic member is fixed so as to be located between any two of the spiral grooves. The method for manufacturing an optical cable according to claim 1, wherein a groove spacer is used. 6. A multi-groove spacer having a plurality of SZ-shaped spiral grooves formed on an outer periphery thereof as the central member, and the ferromagnetic member is housed in any of the spiral grooves. The method for manufacturing an optical cable according to any one of claims 1 to 4. 7. A method in which a plurality of optical fiber units including the optical fiber are used, and the optical fiber units are SZ-twisted around the central member and assembled, and the optical fiber units are assembled around the central member. Wherein the ferromagnetic member is supplied along one of the optical fiber units.
5. The method of manufacturing an optical cable according to any one of items 4 to 4. 8. Using a plurality of optical fiber units including the optical fiber, the optical fiber units are SZ-twisted around the center member, and are assembled together. The method for manufacturing an optical cable according to claim 1, wherein the ferromagnetic member is fixed. 9. The method for manufacturing an optical cable according to claim 7, wherein the optical fiber unit comprises a single groove spacer accommodating the optical fiber. 10. The method according to claim 7, wherein the optical fiber unit is a loose tube.