JP2692293B2 - Optical fiber with metal tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical fiber containing a metal tube.

[Prior Art] An optical fiber containing a metal tube is a cable considered by the latest technology, and there are few examples. In the conventional technology, a structure in which an optical fiber is put in a plastic tube such as polyethylene has been put into practical use. The end of the plastic tube is covered with a simple heat shrink tube.

One of them is that the diameter of the heat-shrinkable tube is comparatively larger than the diameter of the built-in optical fiber, and because it is made of plastic, it is considered that burrs and edges of the cut surface of the heat-shrinkable tube have less effect on the optical fiber. It is thought to be because it is.

However, in the case of an optical fiber containing a metal tube, the gap between the metal tube and the optical fiber is small, and countermeasures against burrs and edge portions of the cut section of the metal tube are important problems.

That is, as shown in FIG. 3, in order to cut the metal pipe 2 without damaging the optical fiber 1 at the end of the optical fiber containing the metal pipe, the metal pipe 2 is cut off with a pipe cutter or a blade 3. After scratching the circumference on the radial side, the metal tube 2 is bent and cut. In this case, the inner surface side of the end of the metal tube 2,
That is, minute burrs and edges 4 are generated on the side where the optical fiber 1 is incorporated.

Considering structurally the relationship between the metal tube 2 and the optical fiber 1, a small gap is provided in the optical fiber 1 so that tension or compression force is hard to be applied to the optical fiber 1 when a bending force is applied to the metal tube 2 in the manufacturing method. It is being done.

[Problems to be Solved by the Invention] An optical fiber of an optical fiber containing a metal tube has slack in the metal tube even when a bending force is applied to the metal tube, and the optical fiber is deformed along the bent shape of the metal tube, It is designed not to break. However, when the optical fiber from which the metal tube is removed is bent near the end of the metal tube, the rigidity of the metal tube is so strong that the end surface of the metal tube is easily bent. In this case, if there is a burr or an edge on the end face of the metal pipe, there is a risk of breaking the wire.

The present invention has been made in view of the above points, and even if bending is applied at the end of the metal tube, the metal tube is not affected by burrs or edges of the cut end surface of the metal tube, and it is possible to prevent local bending from occurring. It is an object of the present invention to provide an input optical fiber.

[Means for Solving the Problem] The above-mentioned object is to insert an optical fiber projecting from a metal tube at an end of a metal tube into a metal tube end side of the projecting optical fiber, and A first heat-shrinkable tube that is in contact with the end of the metal tube and has an outer diameter after heat shrinkage that is substantially the same as the outer diameter of the metal tube, and is provided across the first heat-shrinkable tube and the metal tube. And a second heat-shrinkable tube.

[Operation] Since the above means is provided, the gap between the optical fiber and the metal tube is maintained even when bending is applied at the end of the metal tube, and bending stress is dispersed in the length direction. Prevents contact with burrs or edges of the cut surface of the metal tube and local bending.

EXAMPLES Hereinafter, the present invention will be described based on the illustrated examples.
1 and 2 show one embodiment of the present invention. Since the same parts as those of the conventional one are designated by the same reference numerals, the description thereof will be omitted. In this embodiment, the optical fiber 1 projecting from the metal tube 2 at the end of the metal tube 2 is inserted into the optical fiber 1 and abutted on the end of the metal tube 2 and after thermal contraction. A first heat-shrinkable tube 5 whose outer diameter is substantially the same as the outer diameter of the metal tube 2, and a second heat-shrinkable tube 5a provided across the first heat-shrinkable tube 5 and the metal tube 2. Configured with. By doing so, even if bending is applied at the end of the metal tube, the gap between the optical fiber 1 and the metal tube 2 is maintained, and the bending stress is dispersed in the longitudinal direction, so that the optical fiber 1 It will not touch the burrs and edges of the metal pipe cut surface and will not locally bend, and even if bending is applied at the metal pipe end, it will not be affected by the burrs and edges of the metal pipe cutting end face, and It is possible to obtain an optical fiber containing a metal tube capable of preventing local bending from occurring.

That is, first, as shown in FIG. 1, a first heat-shrinkable tube 5 having a dimension such that the outer diameter thereof after heat shrinkage is the same as the outer diameter of the metal tube 2 is butted against the end of the metal tube 2. After being attached to the optical fiber 1 as described above, the second heat-shrinkable tube 5a is attached so as to bridge the metal tube 2 and the first heat-shrinkable tube 5. In this case, the first heat-shrinkable tube 5
When a bending force is applied to the optical fiber 1 by making the end of the second heat-shrinkable tube 5a shorter than the end of
Since the optical fiber 1 is not partially bent, the optical fiber 1 does not come into contact with burrs and edges, and the disconnection can be prevented. Further, as shown in FIG. 2, since the first and second heat shrinkable tubes 5 and 5a are provided, the bending stress of the optical fiber 1 is dispersed in the length direction.

As described above, according to the present embodiment, it is not necessary to take measures for removing burrs and edges on the cut surface of the metal tube of the optical fiber with a metal tube made of a thin metal tube, and it is necessary to improve work efficiency and skill during assembly processing. Work that is not done is planned.

[Advantages of the Invention] As described above, according to the present invention, an optical fiber protruding from a metal tube at an end portion of the metal tube is inserted into the metal tube end side of the protruding optical fiber, and A first heat-shrinkable tube which is in contact with the end of the tube and whose outer diameter after heat shrinkage is substantially the same as the outer diameter of the metal tube, and which is provided across the first heat-shrinkable tube and the metal tube. Since the second heat-shrinkable tube is provided, a gap is maintained between the optical fiber and the metal tube even if bending is applied at the end of the metal tube, and bending stress is dispersed in the length direction. As a result, the optical fiber will not come into contact with burrs or edges on the cut surface of the metal tube and will not locally bend, and even if bending is applied at the end of the metal tube, the burrs and edges on the cut surface of the metal tube will not be affected. In addition, the optical fiber with a metal tube that can prevent the occurrence of local bending You can get iva.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional side view of an embodiment of an optical fiber containing a metal tube of the present invention, and FIG. 2 is a side view showing a state where a terminal portion of the optical fiber of the embodiment is bent. FIG. 1 is a vertical cross-sectional side view showing a state of a metal tube cut end surface and an optical fiber when a metal tube of a conventional optical fiber containing a metal tube is cut. 1: Optical fiber, 2: Metal tube, 5: First heat shrink tube, 5
a: Second heat shrink tube.

Claims (1)

(57) [Claims] 1. A metal tube-containing optical fiber which is inserted into the inside of a metal tube and whose end portion is projected outward from the end portion of the metal tube. A first heat-shrinkable tube, which is inserted into the outer periphery of the metal tube and is in contact with the end of the metal tube and has an outer diameter after heat shrinkage that is substantially the same as the outer diameter of the metal tube, is covered. An optical fiber containing a metal tube, wherein the outer circumference of the first heat-shrinkable tube and the metal tube is covered with a second heat-shrinkable tube over them.