JP2001004887A - Pulling eye for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degratdation in the breaking tension, execute safer laying work, and improve fixing work of a tension member to a pulling eye. SOLUTION: In this pulling eye for an optical fiber 10, a terminal part of an optical fiber cable 50 where a tension member 20 composed of a single steel wire is exposed as long as a prescribed length has a formation equipped with an insert hole 35 for inserting the tension member 20 therein, on the center part of itself, and equipped with a bottomed cylindrical body part 60 having a hole 30, formed integrally on the head part, through which a messenger wire is inserted at the time of laying. Through holes 21, 22, 23, 24 reaching the facing opposite surface from a circumferential surface on one side of the body part 60 through the insert hole 35 are formed, and screwing means (steel screws) 70, 70, 70, 70 are screwed into the through holes 21, 22, 23, 24 formed on the upper part of the body part 60 to fix the tension member 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber pulling eye used for laying an optical fiber cable.

[0002]

2. Description of the Related Art The inventors of the present invention have intensively studied the improvement of a pulling eye for an optical fiber cable having a tension member, and particularly effective when the tension member is made of a single steel wire. Eye developed. The pooling eye for an optical fiber described here has been separately applied for a patent by the inventors.

[0003] This optical fiber cable pooling eye (hereinafter referred to as "pooling eye") 14 is shown in FIG.
As shown in FIGS. 6A and 6B, the end portion of the optical fiber cable 50 in which the tension member 20 made of a single steel wire is exposed for a predetermined length, and the tension member 20 is inserted into its own central portion. And a bottomed cylindrical main body 60 integrally formed with a hole (hereinafter referred to as a “towing hole”) 30 through which a messenger wire for towing is inserted at the tip portion when the cable is laid. It has a configuration provided.

The main body 60 has through holes 21, 22, 23, 24 extending from one circumferential surface of the main body 60 through the insertion hole 35 and reaching the opposite surface along the axial direction of the main body 60. Is provided. These through holes 21, 22, 2
, 70 are threaded, and the tension member 20 is vertically moved from the through holes 21, 22, 23, 24 on both sides by screwing means (steel screws) 70, 70,. The tension member 20 inserted is fixed to the main body 60 by pressing the inserted tension member 20 with the screwing means 70, 70, and finally from one portion of the distal end to the end of the optical fiber cable 50. That is, the heat-shrinkable tube 40 covers the screwing means 70, 70,... 70.

The heat-shrinkable tube 40 is provided for the purpose of preventing the body portion 60 of the pulling eye 14 and the terminal portion of the optical fiber cable 50 from being damaged by friction or the like during the laying work and waterproofing. Tubes and the like are preferred.

Reference numeral 80 denotes a synthetic resin, as shown in FIG. 4, which covers the entirety of the stripped slot rod 52, whereby the tape-type optical unit 54 housed in the slot 53 is laminated. And the fiber unit 55 (see FIG. 5).

FIG. 5 shows a structure of a general optical fiber cable 50, in which a tension member 20 is arranged at the center and a slot rod 5 provided with four slots 53 on its outer periphery.
2 are provided. In each slot 53, a fiber unit 55 in which three tape-type optical units 54 in which three optical fibers 5 are arranged in parallel, coated with nylon, and integrated, is laminated. And the slot lot 52
Is covered with a sheath 51.

[0008]

SUMMARY OF THE INVENTION The tension member 20
Is composed of a single steel wire having a circular cross section, and its surface is relatively smooth.

Generally, an optical fiber cable 50 of this type is used.
Laying work, i.e., laying out the ground via a manhole at a predetermined distance through a common groove for cable laying underground through a manhole on the road,
By pulling the pooling eye 14 from the opposite side of the manhole through the messenger wire through the drawing hole 30 of the pooling eye 14, finally the optical fiber cable 50
Will be laid in a common channel where gas pipes, telephone lines, power cables, etc. are laid underground.

In this case, in consideration of the safety of the laying work and the like, a tensile strength (breaking tension) is set so that the tension member 20 does not fall off the pulling eye 14 during the laying work.
Are strictly standardized.

When the tension member 20 is a single steel wire, the breaking tension is specified to be 300 kg or more. In this range, the tension member 20 must be firmly fixed so that the tension member 20 does not come off from the pulling eye 14.

However, in the pulling eye 14 shown in FIGS. 6 (A) and 6 (B), the screwing means 70, 70,... In the case of ordinary use, there is almost no problem. However, a situation in which intense vibration or repetitive tension fluctuates temporarily during the laying work,
In the case of No. 4, since the surface of the tension member 20 is smooth, the tension member 20 is
(See FIG. 3 (C)), which reduces the tightening force and withstands the specified breaking tension. In the worst case, the tension member 20 may fall off during the laying work and cause a serious accident.

According to an experiment, when the pulling eyes 14 were attached to several tension members 20 and the breaking tensions were compared, it was found that the range of the variation in the breaking tension was so large that it could not be ignored. This means that the workability requires skill, and it was found that the work efficiency was poor.

The present invention has been made in order to solve such a conventional difficulty, and even if there is vibration or fluctuation in tension,
An object of the present invention is to provide a pulling eye for an optical fiber, which can prevent a decrease in breaking tension, can perform more secure laying work, and can greatly improve the work of fixing a tension member to a pulling eye.

[0015]

In order to achieve the above object, the present invention has a messenger wire through which a hole is formed integrally at a tip end thereof, and a tension member is inserted into a center portion. An optical fiber pulling eye provided with a bottomed cylindrical main body provided with an insertion hole, and a through hole penetrating through the insertion hole on the opposite surface of the main body facing through the insertion hole, A plurality of the through holes are provided along the axial direction of the insertion hole, and one or both of the through holes are subjected to screw hole processing, and a screwing means is screwed into one of the opposed through holes. Thus, the tension member is fixed to the main body.

Further, by screwing the through hole into the through hole provided on the opposite side of the screw means, the tension member is pressed into the through hole provided on the opposite side of the screw means. By deforming the convex portion, durability against tensile force (breaking tension) is improved.

Further, by alternately screwing the through-holes with the screwing means along the axial direction of the main body, the tension member is inserted into the through-hole provided on the opposite side of the screwing means as described above. To improve the durability against tensile force (breaking tension).

The contact portion of the screwing means with the tension member is flattened to improve the tightening force and prevent the surface of the tension member from being damaged.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a pulling eye for an optical fiber cable according to the present invention will be described with reference to FIGS.
It will be described based on.

Here, the same components as those in the above-described conventional example are denoted by the same reference numerals.

In FIG. 4, a pulling eye 10 for an optical fiber cable is used, similar to the conventional example, to connect the end portion of an optical fiber cable 50 in which a tension member 20 made of a single steel wire is exposed for a predetermined length. An insertion hole 35 for inserting the tension member 20 is provided at the center of the messenger wire at the tip of the messenger wire at the time of installation.
It is called a "towing hole." )) And a bottomed cylindrical main body 60 integrally formed with 30.

The main body 60 has through holes 21, 22, 23, 24 extending from one circumferential surface of the main body 60 to the opposite surface through the insertion hole 35 along the axial direction of the main body 60. Is provided.

Each of these through holes 21, 22, 23, 24
Are threaded. And FIG.
As shown in (A), screwing means (steel screws) 70, 70, 70, 70 are screwed into through holes 21, 22, 23, 24 provided in the upper part of the main body 60 in the figure. The tension member 20 is tightened with a predetermined torque from the upper direction U (the direction of the arrow in the figure). Thereby, the tension member 20
Has a diameter of about 3 mm.
It will be pushed into 1,22,23,24 from an upper direction.

That is, as shown in FIG. 3 (A), the contact surface of the tension member 20 with the screwing means 70 is deformed into a concave shape by the screwing of the screwing means 70, and the opposing surface is deformed by a convex portion.

As a result, the durability in the direction indicated by the arrow F (tensile force (rupture tension)) in the drawing is improved. In summary, the deformation of the tension member 20 improves the breaking tension.

Note that, as shown in FIG.
0 to the tension member 20 and screwing means 70, 70, 7
After fixing at 0, 70, the through-holes 21, 22, 23, 24 on the lower side of the hollow main body 60 are filled with a synthetic resin adhesive 90, and finally an optical fiber cable is inserted from the tip. The heat-shrinkable tube 40 covers up to 50 terminal portions.

Next, a second embodiment of the present invention will be described with reference to FIGS. 2, 3 and 4.

Here, the same components as those of the first embodiment and the conventional example are denoted by the same reference numerals, and the description thereof will be omitted.

The pulling eye 12 for an optical fiber cable shown in FIGS. 2A and 2B is the same as that shown in FIGS.
Although the configuration is substantially the same as that of the first embodiment shown in (B), the method of fastening the tension member 20 by the screwing means 70 is different. That is, as shown in FIG.
The screwing means 7 is alternately inserted into the through holes 21, 22, 23,
The screwing directions of 0, 70, 70, 70 are changed. In this way, as shown in FIG. 3B, when the tension member 20 is screwed into the screwing means 70, the contact surface of the tension member 20 with the screwing means 70 is deformed into a concave portion, and the opposing surface is convex. Part deforms.

As a result, the durability in the direction of the arrow F (tensile force (rupture tension)) in the figure is improved. According to the experiments performed by the inventors, it was confirmed that even with such a method, the breaking tension and the workability can be improved substantially in the same manner as in the first embodiment described above.

FIGS. 1A, 1B, 2A,
In (B), the through holes 21, 22, 23, and 24 on the side where the screwing means 70 is not screwed do not necessarily need to be threaded. Further, in each embodiment, the screwing by the screwing means 70 is performed at four positions along the axial direction of the main body 60. However, the present invention is not limited to this, and in consideration of the material and thickness of the tension member 20, What is necessary is just to determine arbitrarily in the range which can satisfy | fill a breaking tension regulation value. Further, the tension member 20 is not limited to a single steel wire, but in the case of a steel stranded wire, FIG.
Even in the conventional method shown in FIGS. 7A and 7B, the tension member 2 is tightened by the screwing means 70.
Since the twisting state of 0 is slightly varied, a decrease in breaking tension can be prevented.

According to the experiments conducted by the inventors, the pulling eyes 10 and 12 for optical fiber cables according to the first and second embodiments of the present invention shown in FIGS. 1 and 2 and the conventional optical system shown in FIG. When the fiber cable pulling eyes 14 are compared, the present invention improves the breaking tension by about 15%,
Variation in breaking tension (Comparison of breaking tension when pooling eyes are attached to several tension members)
Was improved by about 60 to 70%.

That is, the fact that the variation in the breaking tension is small indicates that the work for attaching the pulling eyes does not require any skill and the workability can be greatly improved.

[0034]

As described above, the present invention is constructed as described above, so that even if there is vibration or fluctuation in tension, it is possible to prevent a decrease in breaking tension, and to carry out safer laying work.
It is possible to provide an optical fiber pooling eye capable of greatly improving the work of fixing the tension member to the pooling eye.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams showing a first embodiment of a pooling eye for an optical fiber according to the present invention.

FIGS. 2A and 2B are explanatory views showing a second embodiment of the optical fiber pooling eye of the present invention.

FIGS. 3A and 3B are explanatory views showing a deformed state of a tension member according to the first and second embodiments of the present invention. (C)
Explanatory drawing which shows the tension member deformation state concerning a prior art example.

FIG. 4 is a schematic explanatory view of an optical fiber pooling eye according to the present invention and a conventional example.

FIG. 5 is a configuration diagram of an optical fiber cable according to the present invention and a conventional example.

FIGS. 6A and 6B are explanatory views showing a conventional example of an optical fiber pooling eye. 10, 12 ... Pulling eye for optical fiber 20 ... Tension member 21, 22, 23, 24 ... Through hole 30 ... ································································································ .... Main body 70 ........ Screwing means (steel screw)

 ──────────────────────────────────────────────────続 き The continuation of the front page F term (reference) 2H038 CA73 5G375 AA18 CD04 DA16

Claims (5)

[Claims] 1. A messenger wire at its own tip.
A pulling eye for an optical fiber having a bottomed cylindrical body portion provided with an insertion hole for inserting a tension member in a center portion, wherein a through hole is integrally formed, wherein the insertion hole is provided in the body portion. A through hole is provided on the opposite surface of the main body portion that passes therethrough, and a plurality of the through holes are provided along the axial direction of the insertion hole, and a threaded hole is formed in one or both of the through holes. A pulling eye for an optical fiber, wherein a screwing means is screwed into one of the opposed through holes. 2. The pulling eye for an optical fiber according to claim 1, wherein the screwing with the through hole by the screwing means is performed only from the same direction surface of the main body. 3. The pulling eye for an optical fiber according to claim 1, wherein the screwing with the through hole by the screwing means is performed alternately and sequentially from the opposite direction along the axial direction of the main body. 4. The pulling eye for an optical fiber according to claim 1, wherein said tension member is a single steel wire. 5. The pulling eye for an optical fiber according to claim 1, wherein a tip portion of said screwing means, which comes into contact with a tension member, is flattened.