JPH0519153A - Apparatus and method for producing metallic tube clad optical fiber cable - Google Patents

Abstract

PURPOSE:To hold the surplus length of the metallic tube clad optical fiber cable adjusted in advance, to a prescribed value even after it is laid. CONSTITUTION:By controlling a feeding speed of a drawing means 11 and a rotating speed of a capstan 13, tension of a prescribed amount is given to a metallic tube 1b into which an optical fiber is led. In such a state, by a working means 12, bending for generating a plastic area is given repeatedly to the metallic tube 1b, small shrinkage is given in the lengthwise direction, and by saturating this shrinkage amount, a variation of length of the metallic tube 1b is suppressed. Thereafter, by adjusting surplus length of the optical fiber, the surplus length is held to a prescribed value even at the time of laying, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for manufacturing a metal tube-coated optical fiber cable.

[0002]

2. Description of the Related Art A metal tube-coated optical fiber cable is composed of one or a plurality of optical fibers and a metal tube covered with a gap between the optical fibers. This metal tube functions as a tensile strength body that protects the optical fiber, and by ensuring a space between the metal tube and the optical fiber, the optical fiber can be applied to the optical fiber cable even if tension or lateral pressure acts on the optical fiber cable. On the other hand, it prevents the direct application of tension, etc., and makes it difficult for the microbend loss to increase. Further, by filling the space with a suitable filling material such as oil and fat, it is possible to improve environmental resistance such as moisture proof and waterproof.

A method for continuously producing this optical fiber cable coated with a metal tube is disclosed in, for example, JP-A-58-95304 and JP-A-57-100402. This manufacturing method forms a continuously fed metal strip into a metal tube having a vertical gap at the top. The introduction pipe is inserted into the metal pipe through the gap between the metal pipes, and the optical fiber, the gas, and the filler are introduced into the metal pipe by the introduction pipe. After closing the gap of the metal tube into which the optical fiber is introduced, the abutting portion is welded by a laser welding device or the like to manufacture a metal tube-coated optical fiber cable. When manufacturing this metal tube-coated optical fiber cable, the introduction tube is extended to the downstream side of the welding part and inserted downstream, and the welding heat at the welding part and its vicinity is blocked by the introduction tube to form an optical fiber. Prevents thermal damage.

In this metal tube-coated optical fiber cable, in order to prevent a strain force from being applied to the optical fiber due to expansion and contraction in the axial direction due to elongation strain during installation, changes in environmental temperature, etc. The length and the length of the optical fiber are almost the same, or the length of the optical fiber is very small, for example
The extra length of the optical fiber is controlled so that it will be about 0.05% longer.

However, a metal tube coated optical fiber cable
Since bending is applied in the process of fitting the plurality of bulls together or in the process of laying, there is a problem that the outer metal tube shrinks and the extra length adjusted in advance increases by, for example, about 0.2%. This is because the strength of the metal tube as the covering material is increased, and as a result of the diameter reduction and work hardening of the metal tube, work strain and residual stress remain. Since it is difficult to prevent the metal tube-coated optical fiber cable from being bent at the time of manufacturing or laying it, conventionally, for example, as shown in JP-A-63-195610, the metal tube is annealed. Then, a method of removing the processing strain and inserting an optical fiber into this metal tube, or a method of previously controlling the extra length to be minus 0.15%, for example, has been adopted.

[0006]

If the metal tube is annealed in advance before inserting the optical fiber as described above, the mechanical strength of the metal tube becomes small, and when the tension or the lateral pressure acts. There is a possibility that an external force may act directly on the optical fiber. In addition, there is a risk that the metal tube may be slightly bent when the metal tube-covered optical fiber cable is laid and the transmission characteristics of the optical fiber may be deteriorated. For this reason, there have been significant restrictions on the place of use of the metal tube-coated optical fiber cable.

Further, even if the surplus length of the optical fiber is controlled to be negative by a fixed amount in advance, the bending degree of the metal tube varies depending on the laying conditions and the like, and the shrinkage amount of the metal tube varies. It was difficult to control the excess fiber length to a predetermined value.

The present invention has been made to solve the above problems, and manufactures a metal tube-coated optical fiber cable capable of holding a preliminarily adjusted surplus length of an optical fiber at a predetermined value even after installation. It is intended to obtain an apparatus and a manufacturing method.

[0009]

According to the present invention, there is provided an apparatus for producing a metal tube-coated optical fiber cable, wherein a metal strip continuously fed is molded and an optical fiber or a metal tube is formed by welding a butt portion. In a manufacturing apparatus for a metal tube-coated optical fiber cable in which an optical fiber bundle is introduced, the tension of the metal tube between the pulling means for pulling the optical fiber or the metal tube in which the optical fiber bundle is introduced and the winder is predetermined. It is characterized by comprising a tension adjusting means for adjusting the tension and a processing means provided between the pulling means and the tension adjusting means and comprising a plurality of rollers.

It is desirable that the tension adjusting means is a capstan in which a metal tube into which an optical fiber or an optical fiber bundle is introduced is wound plural times.

In the method for manufacturing a metal tube-coated optical fiber cable according to the present invention, the metal tube is adjusted while adjusting the tension of the metal tube into which the optical fiber or the optical fiber bundle is introduced to a predetermined tension or less. It is characterized by straightening and then controlling the excess length of the optical fiber.

[0012]

The work-hardened metal material such as stainless steel has different yield stresses on the tensile side and the compression side. When this material is bent without applying a tensile force and stress above the yield point is applied, the length of the material shrinks due to the difference in the yield stress between the tensile side and the compression side. When this material is bent while applying a tensile force, the amount of shrinkage in the lengthwise direction decreases depending on the magnitude of the tensile force. Causes elongation in the direction.

Therefore, according to the present invention, before the surplus length of the optical fiber is determined, the metal tube in which the optical fiber or the optical fiber bundle is introduced is repeatedly bent while the plastic zone is generated while applying a predetermined tension. To reduce the amount of shrinkage of the metal pipe, remove the processing strain of the metal pipe, and minimize the residual stress to suppress the change in the length of the metal pipe. To do.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. As shown in the figure, the apparatus for manufacturing a metal tube-coated optical fiber cable is a first molding in which a metal strip 1a whose tension is adjusted by a dancer roll stand 3 is formed and both ends are abutted to form a metal tube 1. Roll group 4, second molding roll group 5, first molding roll group 4 and second molding roll
An optical fiber or an optical fiber bundle (hereinafter referred to as an optical fiber), which is provided between the roll group 5 and before the first molding roll group 4 and whose tension is adjusted by the dancer roll stand 7
It has an optical fiber introducing device 6 for introducing 2.

A metal tube 1 is provided on the exit side of the second forming roll group 5.
There is provided a welding device 8 for welding the butt portion. In the subsequent stage of the welding device 8, an inspection device 9 for inspecting the pulled speed of the welded metal pipe 1 and the presence or absence of a welding defect, and reducing the diameter of the welded metal pipe 1 into a metal pipe 1b having a predetermined outer diameter. The diameter reducing means 10 is connected in series.

A pulling means 11 made of, for example, an endless track type capstan is provided at the rear stage of the diameter reducing means 10, and a processing means 1 having a plurality of rolls is provided at the rear stage of the pulling means 11.
2, a capstan 13, a dancer roll 14, and a winder 15 are connected in series. As shown in FIG. 2, the capstan 13 is composed of a pair of rolls 13a and 13b, one roll 13a having a smooth surface, and the other roll 1a.
A plurality of grooves are formed on the surface of 3b, and the metal tube 1b containing the optical fiber 2 is wound a plurality of times without overlapping. The dancer roll 14 is also a pair of rolls 14a, 14
b, by moving the position of one roll 14b in the direction of the arrow to change the repulsive force between the rolls 14a and 14b, the tension at the exit side of the capstan 13 of the metal tube 1b and the winding The tension on the entry side of the machine 15 is adjusted.

In the manufacturing apparatus constructed as described above, the metal strip 1a wound in a coil shape is required by the pulling means 11 in the molding schedule while the tension is adjusted by the dancer roll stand 3, for example. 15kgf
Is pulled by the pulling force of the first molding roll group 4 and is primarily molded into a substantially U shape by the first molding roll group 4. After that, the metal pipe 1 is formed into a tubular shape by the second forming roll group 5 and has a butt portion at the upper portion.
Is formed. An optical fiber introducing device 6 is provided in the metal tube 1.
The optical fiber 2 is continuously sent through the introduction pipe 61 of the. At the same time, a cooling gas, an inert gas, or a moisture-proof and waterproof filler is supplied from a supply pipe 63 connected to the manifold 62 of the optical fiber introducing device 6, and sent from the introduction pipe 61 into the metal pipe 1.

In this state, the butt portion of the upper portion of the metal tube 1 is irradiated with laser light from the welding device 8 and welded to form the sealed metal tube 1 containing the optical fiber 2. When the abutting surface of the metal tube 1 is welded, the introduction tube 61 that guides the optical fiber 2 is pressed against the inner wall of the metal tube 1 on the side opposite to the welding surface, whereby the metal is continuously formed and sent. Even if vibration or the like occurs in the pipe 1, the introduction pipe 61 can always be positioned on the side opposite to the welding surface 14, and the distance between the introduction pipe 61 and the welding surface can be always kept constant. Then, the heat influence of welding on the introduction pipe 61 and the optical fiber 2 guided by the introduction pipe 61 can be reduced. Further, by supplying a cooling gas or the like from the supply pipe 63 to cool the introduction pipe 63 and the optical fiber 2 in the vicinity of the welded portion, it is possible to further reduce the thermal influence of welding. Although the case where the butt portion of the metal tube 1 is laser-welded has been described, the heat effect of welding can be similarly reduced when welding is performed by electron beam welding, TIG welding, or the like. Further, in this way, the introduction pipe 61 is pressed against the inner wall on the side opposite to the welding surface so that the distance from the welding surface is always kept at the maximum.
Even if welding spatter is deposited on the upper surface of the metal pipe 1, the metal pipe 1 does not come into contact with the metal pipe 1, and long-time operation can be performed.

After the welded portion of the metal tube 1 containing the optical fiber 2 is inspected by the inspection device 9, the diameter reducing means 10 gives a predetermined outer diameter, for example, a thickness of 0.1 mm, an outer diameter of 1.3 mm to an outer diameter. The diameter is reduced to a 1.0 mm metal tube 1b. Thus, the metal tube 1 made of stainless steel having an outer diameter of 1.3 mm is 1.0 mm in outer diameter by the diameter reducing means 10.
When the diameter of the metal tube 1b is reduced, the yield stress of the work side of the metal tube 1b is different between the tensile side and the compression side. When the metal pipe 1b is bent without applying a tensile force to apply a stress equal to or higher than the yield point, the length is shortened due to the difference in the yield stress between the tensile side and the compression side. When the metal pipe 1b is bent while exerting a small tensile force, the amount of contraction in the lengthwise direction becomes small depending on the magnitude of the tensile force, and thus 5 kgf
If the metal tube 1b is bent while applying a tensile force, the amount of shrinkage of the metal tube 1b becomes almost zero. The amount of shrinkage of this metal tube 1b is
As shown in FIG. 3, it is saturated when the workability of repeated bending is increased. Thus, even if the metal tube 1b whose contraction amount is saturated is further bent, the variation in the length direction does not occur.

Therefore, the metal tube 1b whose diameter has been reduced by the diameter reducing means 10 is sent to the processing means 12 and is subjected to strong bending. For example, the metal pipe 1b reduced in outer diameter from 1.0 mm to 30 mm in outer diameter to 1.0 mm by controlling the feed speed of the pulling means 11 and the rotation speed of the capstan 13 has a tensile force of, for example, 2 kgf. It is adjusted and sent to the processing means 12. This metal tube 1b
The processing means 12 repeatedly performs bending by which a plastic region is generated to give a small shrinkage in the length direction of the metal tube 1b, saturates the shrinkage amount, removes the processing strain of the metal tube 1b, and eliminates residual stress. The capstan as small as possible
Send to 3.

When the metal tube 1b passes through the capstan 13, it is wound around the rotationally driven capstan 13 a plurality of times and pulled by frictional engagement with the surface of the capstan 13. In addition, the optical fiber 2 loaded in the metal tube 1b
Is pulled together with the metal tube 1b by frictional engagement with the inner surface of the metal tube 1b. When the metal tube 1b is pulled by the capstan 13, the tension between the metal tube 1b and the optical fiber 2 gradually decreases along the path from the entrance side to the exit side of the capstan 13. In this way, the tension between the metal tube 1b and the optical fiber 2 is reduced by the capstan 13 so that the extension amount of the metal tube 1b and the optical fiber 2 on the entrance side of the capstan 13 is made different, and the extra length of the optical fiber 2 is increased. Is controlled to be substantially zero, or the length of the optical fiber 2 is slightly longer than the length of the metal tube 1b.

For example, a metal tube 1 made of stainless steel having a thickness of 0.1 mm and an outer diameter of 1.3 mm is reduced to an outer diameter of 1.0 mm and strongly bent by a processing means 12 at the capstan 13 entry side of the metal tube 1b. When the tension is adjusted to 2 kgf, the tension causes the metal tube 1b on the capstan 13 entrance side to have a 0.05
% Elongation occurs. At this time, if the tension of the optical fiber 2 having a diameter of 0.25 mm is adjusted to 20 gf, the optical fiber 2 is stretched by 0.02% on the side where the capstan 13 is inserted. Metal tube 1 when this metal tube 1b is wound around the capstan 13
FIG. 4 shows changes in the elongation rate of b and the optical fiber 2. In FIG. 4, A shows the change characteristic of the elongation rate of the metal tube 1b, and B shows the change characteristic of the elongation rate of the optical fiber 2. As shown in the figure,
When the metal tube 1b is wound around the capstan 13 about 6 times, the elongation becomes almost zero. Further, the optical fiber 2 has zero elongation after being wound about once and a half times. When the elongation of the optical fiber 2 becomes zero, the metal tube 1b has about 0.03%
Therefore, the metal tube 1b is apparently shorter than the optical fiber 2 by 0.03% on the exit side of the capstan 13. On the other hand, there is a winding diameter difference between the metal tube 1b wound around the capstan 13 and the optical fiber 2. For example, when the diameter of the capstan 13 is 1 mm, the optical fiber 2 is approximately 0.03% of the metal tube 1b. It has a considerable amount of elongation. If this winding diameter difference and the elongation due to tension are canceled out, the metal pipe 1b
And the extension of the optical fiber 2 are almost the same.
The extra length of can be controlled to almost zero.

The metal tube-coated optical fiber cable in which the extra length of the optical fiber 2 is controlled when passing through the capstan 13 is wound on the winder 15 via the dancer roll 14.

Before the surplus length is determined in this way, the processing means 12
As a result of re-bending the metal tube-coated optical fiber cable which was subjected to the strong bending process at 1, the change in the excess length of the optical fiber was hardly recognized.

[0025]

As described above, according to the present invention, before the surplus length of the optical fiber is determined, a plastic region is generated while applying a predetermined tension to the metal tube into which the optical fiber or the optical fiber bundle is introduced. The metal pipe is processed by repeatedly bending it to give a small shrinkage in the length direction of the metal pipe, saturate the shrinkage amount, remove the processing strain of the metal pipe, and minimize the residual stress. Even if a plurality of coated optical fiber cables are combined and processed into a high-density type, or if bending is applied during installation, the outer metal tube can be prevented from shrinking.

Further, by correcting the metal tube into which the optical fiber or the optical fiber bundle is introduced to prevent the length from changing due to bending, the extra length of the optical fiber is adjusted to obtain a predetermined extra length. (EN) A metal tube-coated optical fiber cable having a good quality can be stably manufactured, and its surplus length can be maintained at a predetermined value even during installation, etc. You can

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a side view showing a capstan and a dancer roll.

FIG. 3 is a characteristic diagram showing a correction degree and a shrinkage rate.

FIG. 4 is a change characteristic diagram of elongation rates of a metal tube wound around a capstan and an optical fiber.

[Explanation of symbols]

1 metal tube 1a metal strip 2 optical fiber 4 First forming roll group 5 Second forming roll group 6 Optical fiber introduction device 8 welding equipment 10 Diameter reduction means 11 Towing means 12 Processing means 13 Capstan 14 Dancer 15 Winder

Claims (3)

[Claims] 1. A metal tube-covered optical fiber cable for forming an optical fiber or an optical fiber bundle into a metal tube formed by molding a continuously fed metal strip and welding a butt portion.
In a bull manufacturing apparatus, a tension adjusting means for adjusting the tension of the metal tube between the winder and the pulling means for pulling the metal tube into which the optical fiber or the optical fiber bundle is introduced, and the pulling means. And a tension adjusting means, and a processing means comprising a plurality of rollers, and a metal tube-coated optical fiber cable manufacturing apparatus. 2. The apparatus for manufacturing an optical fiber cable coated with a metal tube according to claim 1, wherein the tension adjusting means is a capstan in which a metal tube into which an optical fiber or an optical fiber bundle is introduced is wound a plurality of times. 3. A metal tube-covered optical fiber cable for forming an optical fiber or an optical fiber bundle in a metal tube formed by molding a continuously fed metal strip and welding a butt portion.
In the manufacturing method of a bull, the tension of a metal tube into which an optical fiber or an optical fiber bundle is introduced is adjusted to a predetermined tension or less, and the excess length of the optical fiber is controlled after processing the metal tube. And a method for producing a metal tube coated optical fiber cable.