JPH0875968A - Manufacture of self-supported optical cable - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a self-supported optical cable which is easy to manufacture and make the optical cable have the compressive strain equal in magnitude to the extensional strain caused in the optical cable at the time of installing the cable. CONSTITUTION: In the manufacturing method for the self-supported optical cable in which the optical cable 3 constituted by assembling optical fibers is sent to an extruding and coating machine 7 while adding supporting wires 1 consisting of metals, etc., then a sheath is extruded and coated on the optical cable 3 and the supporting wires 1 in one batch to have the supporting wires mainly bear the tensile force, the speed of sending the optical cable 3 to the extruding and coating machine 7 is made higher than the speed of sending the supporting wires 1 and the speed of drawing these out of the extruding and coating machine 7 to compress the optical cable 3 so as to cause the compressive strain equal in magnitude to the extensional strain caused in the optical cable 3 at the time of installing the cable.

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 self-supporting optical cable in which a supporting wire is attached to an optical cable to integrate it, and in particular, elongation strain generated in the optical cable at the time of installation has compressive strain of equal magnitude. In addition, the present invention relates to a method for manufacturing a self-supporting optical cable that is easy to manufacture.

[0002]

2. Description of the Related Art Self-supporting optical cables are widely used as aerial optical cables. As shown in FIG. 2, the self-supporting optical cable 21 includes an optical cable 3 in which a single or a plurality of optical fibers 22 are assembled by twisting or the like,
The support wire 1 is composed of a single or a plurality of galvanized steel wires 23 and the like, and an outer cover 24 that bundles these. The self-supporting optical cable 21 is configured such that the optical cable 3 and the supporting wire 1 are integrated so that the tension applied during installation is mainly applied to the supporting wire 1. This type of self-supporting optical cable is easy to hold on a utility pole,
Further, it is widely used because of its easy manufacturing method.

The manufacturing method is as follows. A support wire 1 made of a single or a plurality of galvanized steel wires 23 or the like is separated for a predetermined distance from an optical cable 3 in which a single or a plurality of optical fibers 22 are assembled by twisting or the like. And the outer jacket 24 is collectively covered by extrusion coating.

[0004]

By the way, when a self-supporting optical cable is installed between utility poles, a tension of several hundred kg is applied to the supporting wire, and its elongation rate reaches 0.5%. As a result, 0.5% elongation is also generated in the optical cable. On the other hand, the optical fiber forming the optical cable has a problem in transmission characteristics, long-term reliability, etc. when the elongation exceeds 0.2%.

It is possible to make the support wire thicker and stronger in order to prevent a large elongation during the installation, but the outer diameter of the self-supporting optical cable becomes thicker and the weight increases, so that the installation becomes difficult. Along with this, the unit price increases and it is uneconomical.

Japanese Utility Model Publication No. 56-47503, JP-A-63-
The technology known from No. 287918 or the like is to apply tension to a support wire in advance in a manufacturing process, integrate the support wire and an optical fiber by coating, and then remove the tension. As a result, the self-supporting optical cable that has become a product has the optical fiber compressed, and there is a margin to extend the optical fiber with respect to the extension of the supporting wire that occurs during installation.

However, these methods attempt to compress the optical fiber by removing the tension of the supporting wire,
Since the optical fiber is not directly compressed, it is difficult to give the desired compressive strain to the optical fiber.

Also, these methods result in shrinkage of the coated product, which results in less product available relative to the manufacturing capacity of the coating process.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a manufacturing method of a self-supporting optical cable which is easy to manufacture, in which the elongation strain generated in the optical cable at the time of installation has a compressive strain of the same magnitude. It is in.

[0010]

In order to achieve the above object, the present invention provides an optical cable formed by assembling optical fibers with a supporting wire made of metal or the like and sending the optical cable to an extrusion coating machine to form an optical cable and a supporting wire. In a method for manufacturing a self-supporting optical cable in which the outer cover is extrusion-coated at one time and the tension applied during installation is mainly applied to the support wire, the speed at which the optical cable is sent to the extrusion coating machine, the speed at which the support wire is sent, and The optical cable is compressed at a speed higher than the speed at which the optical cable is pulled out from the extrusion coating machine, so that the compressive strain having the same magnitude as the stretching strain generated in the optical cable during installation is generated.

The optical cable may be sandwiched between a pair of endless tracks, and the optical cable may be fed into an extrusion coating machine, and the feeding speed of this endless track may be made faster than the discharge speed of the extrusion coating machine at a rate according to the compression strain.

[0012]

With the above construction, since the speed of feeding the optical cable to the extrusion coating machine is faster than the speed of pulling it out of the extrusion coating machine, the optical cable is integrated with the support wire in a compressed state. This compression occurs only in the optical cable, the support line is not compressed. The support wire is attached to the optical cable core, and the jacket is extrusion-coated on the optical cable and the support wire at a time, whereby integration is achieved. In this self-supporting optical cable that has been integrated into a product, the optical cable is in a compressed state, and there is a margin for the optical cable to extend with respect to the extension of the supporting wire that occurs during installation. Since the optical cable is compressed so that the compressive strain of which the magnitude is equal to the extension strain generated in the optical cable at the time of installation, the optical cable has no distortion at the time of installation.

According to this method, since the optical cable is directly compressed, it is easy to obtain a desired compression strain. In addition, since the compression is performed at a higher speed than the speed at which the material is fed in, the difference in speed directly appears in the compression strain, and it is easy to obtain the desired compression strain. Further, since the product exiting the extrusion coater does not shrink, the product amount can be obtained according to the production capacity of the extrusion coater.

By feeding the optical cable to the extrusion coating machine while sandwiching the optical cable between a pair of endless tracks, the feeding speed can be controlled at the speed of the endless track. The desired compression strain can be easily obtained by increasing the feeding speed of the endless track from the discharge speed of the extrusion coating machine at a rate according to the compression strain.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a manufacturing process of a self-supporting optical cable according to the present invention. As shown, a supporting wire drum 2 for accommodating a supporting wire 1 formed by twisting seven galvanized steel wires, and an optical cable drum 4 for accommodating an optical cable 3 formed by assembling seven optical fibers. And a delivery mechanism 5 composed of a pair of endless tracks provided with the optical cable 3 interposed therebetween, and a pipe 6 having an inner diameter substantially equal to the outer diameter of the optical cable 3.
The extrusion coating machine 7 that collectively coats the optical cable 3 and the support wire 1 with the jacket, the water tank 8 for cooling the self-supporting optical cable 21 coming out of the extrusion coating machine 7, and the self-supporting optical cable 21 are sandwiched. And a controller 10 for increasing the speed of the feeding mechanism 5 at an arbitrary rate from the speed of the drawing mechanism 9, and a winding drum 11 for winding the self-supporting optical cable 21 as a product. Composed of.

In FIG. 1, the supporting wire 1 is supplied from the supporting wire drum 2, and the optical cable 3 is supplied from the optical cable drum 4. The optical cable 3 is forcibly delivered by the delivery mechanism 5. The sent out optical cable 3 is guided through a pipe 6 and taken into an extrusion coating machine 7. In the extrusion coating machine 7, the support wire 1 is vertically laid parallel to the optical cable 3 with a predetermined space between them, and the outer cable is applied in this state. The self-supporting optical cable 21 discharged from the extrusion coating machine 7 is cooled in the water tank 8 and then reaches the drawing mechanism 9. The speed at which the pull-out mechanism 9 pulls out the self-supporting optical cable 21 is the same as the discharge speed of the extrusion coating machine 7. The self-supporting optical cable 21 discharged from the drawing mechanism 9 is the product of the winding drum 11 as a product.
To be wound up.

During this time, the controller 10 obtains the compressive strain from the extension strain generated in the optical cable 3 at the time of installation, and speeds up the speed of the sending mechanism 5 at a rate corresponding to the compressive strain with respect to the speed of the drawing mechanism 9. Control. For example, when the elongation rate is 0.5%, the compression rate is 5%, so the speed of the delivery mechanism 5 is controlled to be 0.5% higher than the speed of the drawing mechanism 9. Since the optical cable 3 is fed into the extrusion coating machine 7 faster than being pulled out from the extrusion coating machine 7, and the escape in the line side direction is restricted by the pipe 6,
It is compressed by 0.5% in the direction of the line axis. On the other hand, the speed of feeding the support wire is the same as the discharge speed of the extrusion coating machine 7. Therefore, the self-supporting optical cable 21 in which only the optical cable 3 is compressed is discharged from the extrusion coating machine 7, and this compressed state is maintained thereafter.

When the self-supporting optical cable 21 manufactured in this manner is installed between electric poles, tension is applied to the supporting wire 1 and elongation occurs. The elongation in this example is 0.5%
Becomes As a result, 0.5% elongation also occurs in the optical cable 3, but this is offset by the 0.5% compression given during manufacturing,
There will be no distortion. Therefore, the erected self-supporting optical cable does not cause any problems in transmission characteristics and long-term reliability.

[0020]

The present invention exhibits the following excellent effects.

(1) Since the optical cable is compressed and integrated with the support line, compression can be performed directly, and accurate compression strain can be obtained. Therefore, it becomes easy to obtain the compressive strain having the same magnitude as the elongation strain, and the manufacturing becomes easy.

(2) The product discharged from the extrusion coating machine does not shrink, and the product amount according to the production capacity of the extrusion coating machine is obtained.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a self-supporting optical cable according to the method of the present invention.

FIG. 2 is a cross-sectional view of a self-supporting optical cable.

[Explanation of symbols]

 1 Support Wire 3 Optical Cable 5 Feeding Mechanism 7 Extrusion Coating Machine 9 Drawing Mechanism 10 Controller 12 Endless Track

Claims (2)

[Claims] 1. A support cable made of metal or the like is attached to an optical cable formed by assembling optical fibers and fed into an extrusion coating machine,
In a method for producing a self-supporting optical cable in which an optical cable and a support wire are extrusion-coated at one time so that the tension applied during erection is mainly applied to the support wire, the speed at which the optical cable is sent to an extrusion coating machine is set to the support wire. Of the self-supporting optical cable, characterized in that the optical cable is compressed at a speed higher than the speed of feeding the same and the speed of pulling them out from the extrusion coating machine, so that the elongation strain generated in the optical cable at the time of installation causes a compressive strain of equal magnitude. Production method. 2. An optical cable is sent to an extrusion coating machine by sandwiching the optical cable between a pair of endless tracks, and the feeding speed of this endless track is made faster than the discharge speed of the extrusion coating machine at a rate according to the compression strain. Item 2. A method for manufacturing a self-supporting optical cable according to Item 1.