JPH0681383B2 - Optical fiber composite optical fiber slack imparting method for overhead ground wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical fiber slack imparting method for an optical fiber composite overhead ground wire which reduces the load applied to the optical fiber.

[Prior Art] Recently, an optical fiber composite overhead ground wire (OPGW) in which an overhead ground wire and an optical fiber are combined is used. OPGW is always under tension due to overhead lines, and the cable stretches at high temperatures and strong winds, so it is unavoidable that the optical fiber stretches and strains. When a large elongation or strain is applied to the optical fiber, the wire may be broken after a certain period of time. Therefore, there has been a problem that an optical fiber having high strength must be used to prevent this. Further, since the optical fiber is directly accommodated in the slot of the slotted metal body by using a twisting machine or the like, there is a margin in the slot and there is a drawback that almost no slack can be taken.

[Problems to be Solved by the Invention] In the case where the optical fiber is directly accommodated in the slot formed in the metal body as described above, almost no slack is taken in the optical fiber, and after the cable is installed, strain remains and the optical fiber remains. There is a problem that the life of the fiber is shortened. Further, an optical fiber having high strength has to be used in order to cope with the elongation and strain applied to the optical fiber, which is expensive.

Therefore, it is an object of the present invention to provide an optical fiber slack imparting method for an OPGW, which solves the above-mentioned drawbacks of the prior art and is inexpensive and can prolong the life of the optical fiber.

[Means for Solving Problems] An optical fiber slack imparting method for an OPGW according to the present invention is an optical fiber unit in which a thermoplastic hollow body is interposed in a slot provided in a metal body and an optical fiber is accommodated therein. After forming an OPGW by twisting aluminum-coated steel wires around its outer circumference, the thermoplastic hollow body is deformed to reduce the volume occupied by the hollow body in the slot and to give slack to the optical fiber. It is the one.

[Operation] The optical fiber is accommodated in the slot provided in the metal body by using a twisting machine or the like. Therefore, the optical fiber is tightly stretched in the slot, and there is no room for loosening. If an elastic body is provided in the slot, it is possible to give slack to the optical fiber by its elasticity, but the elastic body is elastically displaced by the optical fiber stretched in the slot at the time of accommodation,
Since the deformation cannot be recovered, slack cannot be imparted as a result.

Therefore, in order to impart slack to the optical fiber, the optical fiber is supported and stretched by a member interposed in the slot when the slot is housed, and after the OPGW is completed, the member is pulled out or reduced to reduce the optical fiber. It may be floated in the slot.

[Example] The following will describe an example of the present invention with reference to the accompanying drawings.

The figure shows the optical fiber slack imparting method of OPGW of the present invention.
1 shows an embodiment of OPGW, in which an OPGW 10 includes a rod-shaped metal body 2 having a slot 1 on the surface, a thermoplastic hollow body 3 and a slot 2 housed inside the slot 1 of the metal body 2.
The optical fiber core 4 is housed outside the optical fiber, the optical fiber unit 6 is composed of the metal tube 5 housing these, and the aluminum-coated steel wire 7 is twisted around the outer circumference.

The melting point of the coating material of the optical fiber core wire 4 is the thermoplastic hollow body 3
The melting point is higher than the melting point of. For example, a fluorine resin is generally used as a coating material for the optical fiber core wire 4, polyethylene is used as the thermoplastic hollow body 3, and aluminum is generally used as the material for the slotted metal body 2 and the metal tube 5.

The OPGW10 is wound around the winding frame or after the overhead wire is heated by energizing the metal body 1 to melt only the thermoplastic hollow body 3 without melting the coating material of the optical fiber to reduce the volume. Then, the optical fiber 4 is loosened.

In the above example, the thermoplastic hollow body 3 was heated and melted. However, a thermoplastic hollow body having a small thickness and previously expanded with a gas (or fluid) such as air is used. It is also possible to store it, and after the completion of the OPGW or after the overhead wire, remove the gas to shrink the gas and give it slack.

[Advantages of the Invention] In short, according to the present invention, after the OPGW is formed, the thermoplastic hollow body in the slot is deformed to reduce the volume thereof, so that slack is easily imparted to the optical fiber after the OPGW is formed. can do. As a result, the life of the optical fiber is extended and reliability is improved, and it is not necessary to use an optical fiber having high strength, which is economical.

[Brief description of drawings]

The figure shows the optical fiber slack imparting method of OPGW of the present invention.
It is a cross-sectional view showing an embodiment of OPGW. In the figure, 1 is a slot, 2 is a metal body, 3 is a thermoplastic hollow body, 4 is an optical fiber core wire, 6 is an optical fiber unit, 7
Is aluminum coated steel wire, and 10 is OPGW.

Claims (3)

[Claims] 1. An optical fiber unit in which a thermoplastic hollow body is interposed in a slot provided in a metal body and an optical fiber is accommodated therein to form an optical fiber unit. An optical fiber slack imparting method for an optical fiber composite overhead ground wire, which comprises forming a wire and then deforming the thermoplastic hollow body to reduce an occupied volume of the hollow body in the slot to impart slack to an optical fiber. 2. The step of deforming the thermoplastic hollow body to reduce the occupied volume of the hollow body in the slot is a step of heating the metal body to melt the thermoplastic hollow body. A method as claimed in claim 1 characterized. 3. The step of reducing the volume occupied by the hollow body in the slot by deforming the thermoplastic hollow body is a step of exhausting and contracting the inside of the expanded thermoplastic hollow body. A method as claimed in claim 1 characterized.