JP3257723B2 - Method for manufacturing metal tube coated optical fiber unit - Google Patents

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 a metal tube coated optical fiber unit used for an optical fiber composite overhead ground wire and the like.

[0002]

2. Description of the Related Art In general, an optical fiber composite overhead ground wire has a structure in which a metal tube-coated optical fiber unit is disposed at the center, and a wire for the overhead ground wire is twisted around the optical fiber unit.
The metal tube-coated optical fiber unit used for this has a structure in which a metal member is coated on a core member in which the optical fiber unit is housed in the groove of the grooved spacer.

[0003] Such a metal tube-coated optical fiber unit has conventionally been manufactured as follows. That is, after the optical fiber unit is dropped into the groove of the grooved spacer to produce a core member, a metal tape is vertically attached to the core member, and the core member is rounded so as to wrap the core member, and the joint of the metal tape is arc welded. It is a method of making a metal tube.

[0004]

However, the conventional manufacturing method employs a method in which a metal tape is rounded and formed around a core member including an optical fiber unit, and the joint is arc-welded. It is difficult to perform arc welding so as not to damage the unit, and if the welding conditions fluctuate even a little, there are drawbacks such as poor welding (pinholes, cracks, etc.) and damage to the optical fiber unit.

[0005] When a welding defect occurs, it is impossible to repair it by re-welding because the optical fiber unit is contained therein. For this reason, if a defective accident occurs during the production, it is necessary to start the production again from the beginning, and there is a problem that not only the production efficiency is reduced but also the product yield is significantly reduced.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a metal tube-coated optical fiber unit which solves the above-mentioned problems, and comprises a method of manufacturing a metal tube coil through which a linear body is inserted. And preparing a core member containing the optical fiber unit in the groove of the grooved spacer, connecting the tip of the core member to the rear end of the linear body, pulling the distal end side of the linear body, and inserting the core into the metal tube. The step of drawing in the member and the step of drawing out the metal tube to reduce the diameter are performed in this order .

[0007]

In this way, the manufacture of the metal tube can be performed independently of the optical fiber unit, so that the manufacture of the metal tube is easy and a metal tube free from defects can be used. In particular, it is possible to use a seamless metal pipe manufactured by drawing instead of welding, and if a seamless metal pipe is used, defects such as pinholes will not be a problem. Further, since no welding heat is applied to the optical fiber unit, it is possible to eliminate damage to the optical fiber unit due to heat.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the manufacturing method of the present invention, first, as shown in FIG. 1, a coil of a metal tube 2 wound around a drum 1 and a core member 6 wound around a drum 5 are prepared. It is particularly desirable to use a seamless metal tube as the metal tube 2. The metal tube 2 is usually made of aluminum.

A linear body 3 is inserted into the metal tube 2. The linear body 3 may be inserted after winding the metal tube 2 around the drum 1 or may be inserted while manufacturing the metal tube 2. As the linear body 3, a plastic-coated metal wire can be used. Drum 1 with plastic coated metal wire
When the outer diameter (outer diameter of the coating) of the plastic-coated metal wire is set to 1/5 or less of the inner diameter of the metal pipe 2, the insertion operation can be easily performed. .

As a method for inserting the linear member 3 into the metal tube 2 wound around the drum 1, a pneumatic line method can be adopted. In this method, compressed air is sent from one end of a metal tube 2, and a linear body 3 having a pressure receiving member attached to the tip is sent by a flow of compressed air. When the pneumatic line method is adopted, a lightweight nonmetallic linear body such as a bundle of glass fibers or high-tensile plastic fibers, or an FRP wire may be used as the linear body 3.

On the other hand, the core member 6 wound around the drum 5 is shown in FIG.
The optical fiber unit 9 is housed in the groove 8 (formed in a spiral) of the grooved spacer 7 as shown in FIG. The grooved spacer is usually made of aluminum. The optical fiber unit 9 is an assembly of an appropriate number of optical fibers and tension members.

In the state shown in FIG. 1, the front end of the core member 6 is connected to the rear end of the linear body 3. Thereafter, as shown in FIG. 2, the leading end side of the linear body 3 is taken up by a take-up capstan 11 and taken up by a take-up drum 12 so that the core member 6 is
And pulled into the metal tube 2. At this time, the coil of the metal tube 2 wound around the drum 1 remains stationary,
Both ends of the metal tube 2 are held at fixed positions by clamps 13. The core member 6 is fixed to the metal tube 2 by a guide roll 14.
The linear body 3 which is guided to the entrance of the metal tube 2 and comes out from the exit of the metal tube 2 is guided by a guide roll 15 in a certain direction.

In order to prevent troubles such as catching when the core member 6 is pulled into the metal tube 2 wound with the drum, as shown in FIG. The ratio D ₁ / d to the inner diameter D _{1 of the} tube 2 is
It was confirmed that it was better to set the range of 1.5 ≦ D ₁ /d≦2.0. When a plastic-coated metal wire is used as the linear body 3, when the core member 6 is pulled into the metal tube 2,
Scratching of the inner surface of the metal tube 2 can be prevented.

When the core member 6 is drawn into the metal tube 2 over the entire length, the core member 6 and the linear body 3 are separated. Thereafter, as shown in FIG. 3, the drum 1 around which the metal tube 2 is wound is set on the supply side of the drawing apparatus 21 and is drawn by a plurality of dies 22 and a drawing capstan 23 to reduce the diameter to obtain a desired size. Metal tube coated optical fiber unit 25
This is wound around the winding drum 26. The metal tube 2
Since the core member 6 is elongated in the longitudinal direction by the drawing process, its length is preferably adjusted in advance so that the core member 6 has substantially the same length as the core member 6 after the drawing process.

The metal tube-coated optical fiber unit 25 manufactured as described above has a ratio D ₂ / d of the outer diameter d of the grooved spacer 7 and the inner diameter D ₂ of the metal tube 2 as shown in FIG.
Is most effective in terms of ease of use, such that 1.0 <D ₂ /d<1.5.

[0016]

As described above, according to the present invention, the metal tube can be manufactured completely independently of the core member including the optical fiber unit. A metal tube without any can be used.
In particular, if a seamless metal pipe is used, a defect such as a pinhole does not become a problem. Further, since no welding heat is applied to the optical fiber unit, the optical fiber unit can be prevented from being damaged by heat. Furthermore, since troubles such as discontinuing production do not occur on the way,
There is an advantage that the manufacturing efficiency is good and the manufacturing yield is greatly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first stage of a method for manufacturing a metal tube-coated optical fiber unit according to one embodiment of the present invention.

FIG. 2 is an explanatory view showing a second stage in the same manner.

FIG. 3 is an explanatory view showing a third stage.

FIG. 4 is a sectional view of a core member.

FIG. 5 is a sectional view showing a state where the core member is drawn into the metal tube.

FIG. 6 is a sectional view of a metal tube-coated optical fiber unit manufactured according to an embodiment of the present invention.

[Explanation of symbols]

 1: drum 2: metal tube 3: linear body 6: core member 7: grooved spacer 8: groove 9: optical fiber unit 11: take-up capstan 12: winding drum 21: drawing device 22: die 23: take-up Capstan 25: Metal tube coated optical fiber unit 26: Winding drum

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-25606 (JP, A) JP-A-59-40604 (JP, A) JP-A-64-64518 (JP, A) JP-A 55-604 94509 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21C 1/22 B21C 1/00 B21C 1/32 G02B 6/44 391 B21F 19/00

Claims (5)

(57) [Claims] 1. A step of preparing a coil of a metal tube through which a linear body is inserted, and a core member accommodating an optical fiber unit in a groove of a grooved spacer, connecting a front end of the core member to a rear end of the linear body. A step of pulling the core member into the metal tube by pulling the distal end side of the linear body, and a step of drawing and reducing the diameter of the metal tube in this order. Method. 2. The manufacturing method according to claim 1, wherein the linear body is made of a plastic-coated metal wire, and an outer diameter of the plastic coating is 1/5 or less of an inner diameter of the metal tube. . 3. The manufacturing method according to claim 1, wherein the linear body is a non-metallic light-weight linear body passed through a metal pipe by a pneumatic line method. 4. The manufacturing method according to claim ₁ , wherein a ratio D ₁ / d between an outer diameter d of the grooved spacer and an inner diameter D ₁ of the metal tube before diameter reduction is determined. 1.5 ≦ D ₁ / d ≦ 2.
Characterized as 0. 5. The method according to claim 1, wherein a ratio D ₂ / d between an outer diameter d of the grooved spacer and an inner diameter D ₂ of the reduced metal tube is defined as: 1.0 <D ₂ / d <1.
5