JPS636511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal-coated optical transmission body having a protective layer made of metal and a protective layer made of cushion.

Optical fibers being developed for communications are made of ultra-fine glass called fibers and have very low mechanical strength from a practical standpoint, so various reinforcement and protection measures are required.

For example, one of the above methods is to provide a hard or soft synthetic resin coating on the outer periphery of a bare optical fiber, and it is also possible to provide a metal protective layer on the outer periphery of such a coated optical fiber. This is one of the above means.

Conventionally, as a means for providing a metallic protective layer on the outer periphery of a coated optical fiber, a tape-shaped thin metal strip (hereinafter referred to as metal tape) is attached longitudinally to the outer periphery of the optical fiber and the metal tape is attached. A method has been adopted in which the optical fiber is rolled into a cylindrical shape and both sides of the rolled-in edges are welded. However, when using this method, technical considerations are required to prevent the optical fiber from escaping from the cylindrical shape during the rolling, and technical considerations are required during the rolling. Technical considerations are required to prevent the optical fiber from being accidentally broken, and the wrapping process involves bringing the inner circumferential surface of the metal protective layer as close as possible to the outer circumferential surface of the optical fiber. Processing such as inserting a cushion material into the fiber is becoming more difficult, and furthermore, a welding process is required, and during welding, the plastic sheath of the optical fiber may be thermally deformed or altered, or the transmission characteristics of the optical fiber may be affected. There was also a problem with lowering the value.

On the other hand, it is not unthinkable to put the optical fiber inside a metal tube, but putting the optical fiber inside a metal tube with an extremely small diameter corresponding to the outside diameter of the optical fiber means that both the optical fiber and the metal tube are This is difficult due to the long length of the optical fiber, and in particular, it is technically quite difficult to use such a coating method while interposing a cushion material between the inner periphery of the metal tube and the outer periphery of the optical fiber.

The present invention aims to gradually increase the degree of coverage of the optical fiber in the longitudinal direction of the optical fiber by reducing the diameter and elongating the tube with a metal tube covering the outer periphery of the optical fiber. By interposing a cushion material at a predetermined location in synchronization with this coating, the desired metal-coated optical transmission body can be manufactured simply and without problems.

Hereinafter, the method of the present invention will be explained with illustrations.
In FIG. 1, reference numeral 1 denotes a coated optical fiber, which is a type of optical transmission body, and the coating of the optical fiber 1 includes a buffer coat made of plastic having a small Young's modulus.

2 is a metal tube made of copper (pure copper, brass), aluminum, stainless steel, etc.

In this relative relationship between the optical fiber 1 and the metal tube 2, the optical fiber 1 is considerably longer than the metal tube 2. On the other hand, the inner diameter of the metal tube 2 obtained by rough drawing tube processing is the outer diameter of the optical fiber 1. It is considerably larger than its diameter.

Reference numeral 3 is a fire-resistant cushion material, and as the cushion material 3, a fiber fire-resistant material made of glass fiber or the like having a predetermined layer thickness is mainly used, and other materials such as flame-retardant plastic with a closed cell structure are used. will also be adopted.

Before manufacturing a predetermined metal-coated optical fiber from these optical fiber 1, metal tube 2, and cushion material 3, as shown in FIG. are supported by supports 5a and 5b, and the cushion material 3 can be freely fed by a feeder 6.

In the present invention, in FIG. 1, the unwinding end (tip) of the optical fiber 1 is attached to the outer periphery of the unwinding end of the optical fiber 1 unwinding from the rotating drum 4 while applying the cushion material 3 from the feeder 6. ,5b
The optical fiber 1 is inserted into the upper metal tube 2, and the tip of the optical fiber 1 and the tip of the metal tube 2 are relatively fixed by appropriate means, and the lead wire 8 is connected to the fixing part 7.

Then, the lead wire 8 is inserted into the first die 9a,
The lead wire 8 is pulled through the second die 9b, and the tip of the lead wire 8 is tied to the circumferential surface of a rotating drum 10 that is placed facing the rotating drum 4, and the drum 10 is rotated by the power of a motor or the like. Let it happen.

In this way, the cushion material 3 is attached to the outer periphery.
An optical fiber 1 and a large diameter metal tube 2 are sequentially attached.
In this case, the metal tube 2 is pulled in the winding direction of the rotating drum 8, and at this time, the metal tube 2 is drawn through the first die 9a to reduce its diameter and expand.
As a result, the metal tube 2, which has reached the small diameter state shown in FIG. 1 and the cushion material 3 are wound onto the rotating drum 10.

That is, in the above processing, the diameter of the metal tube 2 is reduced by the first and second dies 9a and 9b into the small-diameter workpiece shown in FIG. 1A and the small-diameter workpiece shown in FIG. Due to the longitudinal elongation, the optical fiber 1
is gradually coated with metal while having a cushion material 3 on its outer periphery, and this is wound around the rotating drum 10 as a metal coated optical fiber.

At this time, the optical fiber 1 is held so as to be freely unwound from the rotating drum 4 and corresponds to the rotating drum 10 to which the pulling force is applied at a constant velocity.
During the die processing of the metal tube 2, no unreasonable tension is applied to the optical fiber 1, and therefore no optical fiber breakage occurs.

Furthermore, since the cushion material 3 is interposed between the optical fiber 1 and the metal tube 2, during the above processing, the inner circumference of the metal tube and the outer circumference of the optical fiber may come into contact and the outer circumference may be damaged. It disappears.

Furthermore, if the metal tube 2 has been work hardened due to diameter reduction processing using the first die 9a, the first
As shown in the figure, the metal tube 2 may be annealed by a heater (cylindrical furnace) 11 placed between both dies 9a, 9b.

FIG. 2 is a sectional view of the metal-coated optical fiber obtained as described above, in which a cushion material 3 is interposed between the optical fiber 1 and the metal tube 2 in a predetermined manner.

In the above embodiment, the coated optical fiber 1 was used as an optical transmission body, and an example was shown in which the outer periphery of the coated optical fiber 1 was coated with metal. However, other optical fibers that are not coated (fiber bare wire),
There are optical cable units in which coated optical fibers are assembled, optical fiber cables in which optical cable units are further assembled, and the method of the present invention is also effective when coating these optical transmission bodies with metal.

Also, two dies 9 are required to reduce the diameter of the metal tube 2.
Although dice a and 9b are used, three or more of these dice may be used.

As explained above, in the method of the present invention, in the relative relationship between the optical transmission body and the metal tube, the optical transmission body is longer than the metal tube, and the inner diameter of the metal tube is formed larger than the outer diameter of the optical transmission body. Prepare the optical transmission body and metal tube, cover the outer periphery of the tip of the optical transmission body with a metal tube, fix the tips of both relatively, and place the metal tube into a die while applying a pulling force to the fixed part. By pulling the metal tube through, the diameter of the metal tube is reduced and expanded, and the extensible metal tube covers the outer periphery of the optical transmission body in the longitudinal direction, and in synchronization with the metal coating process, the outer periphery of the optical transmission body and the inner periphery of the metal tube are coated. A cushion material is interposed between the two.

Therefore, the method of the present invention, which is characterized by the above means, provides the following effects.

One is that compared to the conventional method of vertically splicing metal tape, there are no welded or overlapping parts of the metal, so the strength in the radial direction is uniform, and therefore the metal-coated optical transmitter shown in Figure 2 can be used. Twisting and gathering,
The bending properties when laying these are improved.

Furthermore, unlike conventional methods that require welding, high-temperature heat does not affect internal optical fibers, so there is no deterioration in transmission characteristics, and there is no stress on the optical fibers during manufacture. Since no tension is applied, the optical fiber does not break.

Another advantage is that processes such as welding can be omitted, metal coating can be applied to the optical transmitter at the same time as the diameter of the metal tube is reduced and expanded, and the main processing is only required for the metal tube. Because it is easy to insert the optical transmitter into the metal tube and load the cushion material when the diameter of the metal tube has increased, manufacturing efficiency is increased several times compared to conventional methods, and long metal tubes can be easily processed. Coated light transmitters can also be easily obtained.

Another problem is that a cushion material is interposed between the outer periphery of the optical transmitter and the inner periphery of the metal tube in synchronization with the metal coating process, so the optical transmitter may be damaged by the metal tube during the process. This is prevented by the cushion material, and the protective function of the cushion material satisfactorily protects the optical transmission body during subsequent use and handling.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the method of the present invention, and FIG. 2 is a cross-sectional view of a metal-coated optical fiber obtained by the same method. 1... Optical fiber (a type of optical transmission body), 2...
Metal tube, 3...Cushion material, 9a, 9b...Dice.

Claims (1)

[Claims] 1. In the relative relationship between the optical transmission body and the metal tube, the optical transmission body is longer than the metal tube, and the inner diameter of the metal tube is larger than the outer diameter of the optical transmission body. By preparing a body and a metal tube, covering the outer periphery of the tip of the optical transmission body with the metal tube, fixing the tips of both relatively, and drawing the metal tube through the die while applying a pulling force to the fixed part. The diameter of the metal tube is reduced and expanded, the outer periphery of the optical transmission body is covered in the longitudinal direction with the expandable metal tube, and in synchronization with the metal coating process, a gap is formed between the outer periphery of the optical transmission body and the inner periphery of the metal tube. A method of manufacturing a metal-coated optical transmission body characterized by interposing a cushion material. 2. A method for manufacturing a metal-coated optical transmission body according to claim 1, in which a fire-resistant material is used as the cushion material. 3. A method of manufacturing a metal-coated optical transmission body according to claim 2, in which a fiber fireproof material is used as the cushion material.