JP2002303771A - Sz slot for optical fiber cable and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an SZ slot which can improve productivity and quality and to provide a method for manufacturing the SZ slot. SOLUTION: In the process of manufacturing the SZ slot 8, the temperature of a rotary die 2 is measured by using a radiation thermometer 9 and its temperature information is sent to a temperature control unit. The temperature control unit when judging that the detected temperature is higher than set temperature cools the rotary die 2 by using a rotary die cooling device 10. Namely, the rotary die is cooled by taking air 11 in the rotary die cooling device 10 and blowing the air 11 to the rotary die 2. While extruded resin temperature is thus controlled, a tension member 5 is coated with a slot layer 7 by extrusion and the SZ slot 8 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SZ slot for an optical fiber cable used for a slot type cable or the like and a method for manufacturing the same, and more particularly, to an SZ slot for an optical fiber cable capable of improving productivity and quality. It relates to the manufacturing method.

[0002]

2. Description of the Related Art As a conventional SZ slot, a lower layer made of polyethylene or the like is provided on the outer periphery of a tension member made of a metal wire such as a steel wire or a steel stranded wire, and one or more spiral grooves are formed on the outer periphery of this lower layer. It is known that a slot layer made of polyethylene or the like formed in the SZ direction is formed. Here, the SZ direction is formed by repeating a spiral groove in the S direction and a spiral groove in the Z direction alternately at a certain period, similarly to “SZ twist” known in the field of metal stranded wires. When a single spiral groove is developed into a planar shape, the spiral groove draws a substantially sinusoidal locus. In the method of manufacturing the SZ slot, a metal wire serving as a tension member is supplied to a crosshead die of an extruder, and polyethylene or the like is extrusion-coated on the metal wire to first form a lower layer having a circular cross section. Next, the tension member 5 provided with the lower layer is fed into the mandrel 6 of the crosshead die 1 of the extruder on which the rotating die 2 is mounted as shown in FIG. The resin is extruded, and the SZ slot 8 is formed by covering the slot layer 7 in which one or more spiral grooves in the SZ direction are formed. In such a coating operation of the slot layer 7, in the crosshead die 1 of the extruder, frictional heat is generated as the rotary die 2 rotates, so that the temperature of the rotary die 2 is controlled. As shown in FIG. 4, the thermocouple 4 and the heater 3 are provided in a portion that does not rotate away from the rotary die 2.

[0003]

However, such S
According to the manufacturing method of the Z slot, since the extrusion operation is performed twice to form the lower layer and the slot layer, the workability is poor and the cost is increased. Therefore, in order to improve productivity, it is desirable to directly form the slot layer without providing a lower layer made of polyethylene or the like on the outer periphery of the tension member. Also, by increasing the production line speed of the SZ slot, productivity can be improved. However, increasing the production line speed of the SZ slot causes a problem that the surface roughness of the formed SZ slot becomes rough. Further, the tape cores were assembled in the SZ slot having the rough surface, and the optical fiber cable was formed into a cable and the optical transmission loss of the optical fiber cable was measured. As a result, it was found that the optical transmission loss at a high temperature of around 70 ° C. increased. . FIG. 3 shows the result of investigation on the relationship between the surface roughness of the SZ slot 8 and the maximum optical transmission loss at a high temperature of around + 70 ° C. for an optical fiber cable cabled using the SZ slot. FIG. 3 shows the results of measuring the optical transmission loss of the optical fiber cable at 70 ° C. with respect to the surface roughness of the SZ slot 8. When the surface roughness exceeds 1.0 μm, the optical transmission loss of the optical fiber cable is measured. Is sharply increased, and the fluctuation of the temperature characteristic of the optical transmission loss becomes remarkable. The present invention has been made to solve such problems, and provides an SZ slot for an optical fiber cable capable of improving productivity and quality, and a manufacturing method for manufacturing the SZ slot. The purpose is to provide.

[0004]

In order to solve the above-mentioned problems, the invention according to claim 1 is a resin-made resin having a tension member and one or more spiral grooves in the SZ direction formed on the tension member. An SZ slot for optical fiber cables, comprising a slot layer, wherein the slot layer is an SZ slot obtained by one extrusion coating, and the surface roughness of the SZ slot is 1.0 μm or less. is there. According to a second aspect of the present invention, a metal wire serving as a tension member is fed into a crosshead die of an extruder,
When the molten resin is extrusion-coated on the metal wire by the rotary die of the crosshead die to form a slot layer having one or more spiral grooves in the SZ direction, the temperature of the rotary die is measured. This is a method for manufacturing an SZ slot for an optical fiber cable, wherein According to a third aspect of the present invention, in the second aspect, the temperature control is performed by cooling the rotary die when the temperature in the vicinity of the rotary die becomes equal to or higher than a set temperature.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
FIG. 1 shows an example of a crosshead die used for manufacturing the SZ slot for an optical fiber cable of the present invention.
In FIG. 1, reference numeral 1 denotes a crosshead die. The crosshead die 1 is roughly composed of a rotary die 2, a heater 3, a radiation thermometer 9, and a rotary die cooling device 10. The method of manufacturing the SZ slot includes forming the slot layer by a single extrusion without forming a resin coating in advance on the tension member 5 made of a metal wire such as a steel wire or a stranded steel wire. Is formed. Specifically, a metal wire to be the tension member 5 is introduced into the mandrel 6 and fed into the crosshead die 1 of the extruder. The rotating die 2 of the crosshead die 1 is alternately rotated forward and inverted to extrude the molten resin once onto the metal wire,
The SZ slot 8 is formed by covering the slot layer 7 in which one or more spiral grooves in the SZ direction are formed. An adhesive may be applied to the metal wire in advance to increase the bonding strength between the tension member 5 and the slot layer 7. In the crosshead die 1 of such an extruder, frictional heat is generated with the rotation of the rotary die 2.
In order to control the temperature, a radiation thermometer 9, a heater 3, and a rotary die cooling device 10 are provided.

[0006] The rotation of the rotary die 2 generates frictional heat at the boundary between the rotary part and the fixed part, and this heat generation increases as the number of reversals of the rotary die 2 per unit time increases. When the production line speed of the SZ slot 8 is increased to improve the productivity of the SZ slot 8, the number of reversals increases as the reversal pitch of the rotary die 2 becomes shorter, thereby increasing heat generation. Due to this heat generation, the temperature of the resin extruded from the crosshead die 1 increases, and it is considered that the temperature increase of the resin affects the surface roughness of the SZ slot 8. FIG. 2 shows the result of investigation on the relationship between the extruded resin temperature and the roughness of the SZ slot surface.
As shown in FIG. 2, when the extruded resin temperature exceeds 185 ° C., the surface roughness of the SZ slot 8 rapidly increases.

FIG. 3 shows the relationship between the surface roughness of the SZ slot 8 and the optical transmission loss of the optical fiber cable cabled using the SZ slot.
If the SZ slot 8 is manufactured so that the surface roughness of the slot 8 is 1.0 μm or less, the temperature characteristics of the optical transmission loss of the optical fiber cable formed by using the SZ slot 8 can be improved. be able to. According to this example, S is produced by coating by one resin extrusion.
By setting the surface roughness of the Z slot 8 to 1.0 μm or less, the SZ slot 8 can be used as a cable to manufacture an optical fiber cable having good temperature characteristics of optical transmission loss.

Next, a method of manufacturing the SZ slot 8 so that the surface roughness is 1.0 μm or less will be described with reference to FIG. In this example, in the manufacturing process of the SZ slot 8, means for measuring the temperature of the rotary die 2 and accurately controlling the temperature of the extruded resin is provided. Specifically, the temperature of the rotating die 2 is measured using the radiation thermometer 9, and this temperature information is transmitted to the temperature controller. When the temperature controller determines that the detected temperature is equal to or higher than the set temperature, the temperature controller uses the rotary die cooling device 10 to rotate the rotary die 2.
To cool. The cooling is performed by taking the air 11 into the rotary die cooling device 10 and blowing the air 11 toward the rotary die 2. From the results of the study shown in FIG. 2, the set temperature was set at 165 ° C. to 185 ° C.
It is preferably set to ° C. While performing such temperature control, the outer periphery of the tension member 5 is extrusion-coated with resin to form the slot layer 7 and the SZ slot 8. In addition,
The temperature control method is not limited to this, and the temperature may be measured using a thermocouple, and this temperature information may be extracted as an electric signal via a slip ring and controlled by a temperature controller.

According to this example, since the temperature of the rotary die 2 is measured and controlled, the temperature of the extruded resin can be accurately controlled. Even if the number of reversals of the rotary die 2 is large, an excessive temperature rise of the extruded resin can be prevented, and an SZ slot manufacturing method capable of manufacturing the SZ slot 8 having good surface roughness can be manufactured. Can be realized. Further, when a cable is formed by using the SZ slot 8, an optical fiber cable having good temperature characteristics of optical transmission loss can be manufactured.

(Embodiment) A specific example will be described below. Outer diameter 8.0
mm, a reversal angle of 275 °, and a reversal pitch of 175 mm were produced in a single extrusion with 5 grooves of SZ slots. In manufacturing this SZ slot, the temperature of the rotary die 2 is measured, and when this temperature exceeds the set temperature, the surface of the rotary die 2 is cooled by supplying air 11 from the rotary die cooling device 10 to the surface. The temperature of the extruded resin was controlled. The production linear speed of the SZ slot 8 is 5 m / min, 10 m / min, 15 m / min, 2
The SZ slot 8 was manufactured at 0 m / min and 30 m / min, and the surface roughness of the SZ slot 8 was measured in each case. In addition, an optical fiber cable was produced by assembling a cable by assembling five cores of four cores in each of the SZ slots 8 per groove. Evaluation of the temperature characteristics of the optical transmission loss of this optical fiber cable was performed at -30 ° C to + 70 ° C
The temperature test was performed in a temperature range of 3 cycles.

As a comparative example of this embodiment, as shown in FIG. 4, when the temperature of the extruded resin is controlled at a place away from the rotary die 2, the SZ slot 8 is produced at the same production linear speed as the embodiment. Was manufactured, and the surface roughness of the SZ slot 8 was measured in each case. Further, a cable was formed using the SZ slot 8 in the same manner as in the example, and the temperature characteristics of the optical transmission loss of the optical fiber cable were evaluated. Table 1 shows the SZ for the examples and comparative examples.
9 shows the surface roughness of the slot 8 and the maximum optical transmission loss of the optical fiber cable at 70 ° C.

[Table 1] The optical transmission loss was measured using an OTDR with a wavelength of 1.55 μm.
(Optical Time Domain Reflection) device.

As is clear from Table 1, according to this embodiment, even when the production linear speed of the SZ slot 8 is as high as 30 m / min, the surface roughness of the SZ slot 8 is 1.0 μm or less. The temperature characteristics of the optical transmission loss of the optical fiber cable cabled by the slot 8 are stable. On the other hand, according to the comparative example, when the production linear velocity of the SZ slot 8 is 10 m / min, the surface roughness of the SZ slot 8 is already 1.0 μm. The surface roughness of No. 8 sharply increases. Accordingly, the optical transmission loss of the optical fiber cable is increasing. From the above results, it has been clarified that the method of manufacturing an SZ slot according to this embodiment is useful.

[0013]

As described above, according to the present invention,
By reducing the surface roughness of the SZ slot produced by coating with one resin extrusion to 1.0 μm or less,
An optical fiber cable having good temperature characteristics of optical transmission loss can be manufactured by forming a cable using a Z-slot. According to the present invention, the temperature of a rotary die is measured and the extruded resin is controlled by controlling the temperature. Since the temperature can be controlled accurately, an excessive rise in the temperature of the extruded resin can be prevented even when the number of reversals of the rotary die is large in order to increase the production line speed of the SZ slot. ,
An SZ slot manufacturing method capable of manufacturing an SZ slot having good surface roughness can be realized.

[Brief description of the drawings]

FIG. 1 is a view showing a crosshead die used for manufacturing an SZ slot for an optical fiber cable of the present invention.

FIG. 2 is a diagram showing a relationship between an extruded resin temperature and an SZ slot surface roughness.

FIG. 3 is a diagram showing the relationship between the surface roughness of an SZ slot and the optical transmission loss of an optical fiber cable cabled using the SZ slot.

FIG. 4 is a view showing a crosshead die used for manufacturing a conventional SZ slot for an optical fiber cable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cross head die, 2 ... Rotary die, 5 ... Tension member, 7 ... Slot layer, 8 ... SZ slot 9 ... Radiation thermometer, 10 ... Rotary die cooling device, 11 ... Air

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Suehiro Miyamoto 1440 Mutsuzaki, Sakura City, Chiba Prefecture Fujikura Co., Ltd. Sakura Plant F-term (reference) 2H001 BB10 DD04 KK06 KK12 MM01

Claims (3)

[Claims] An SZ slot comprising a tension member and a resin slot layer having at least one spiral groove in the SZ direction formed on the tension member, wherein the slot layer is obtained by one extrusion coating. An SZ slot for an optical fiber cable, wherein the surface roughness of the SZ slot is 1.0 μm or less. 2. A metal wire to be a tension member is fed into a crosshead die of an extruder, and a molten resin is extrusion-coated on the metal wire by a rotary die of the crosshead die, and one or more spiral grooves in the SZ direction are formed. A method for manufacturing an SZ slot for an optical fiber cable, comprising measuring a temperature of a rotary die and controlling the temperature when forming the formed slot layer. 3. The optical fiber cable SZ slot according to claim 2, wherein the temperature control is performed by cooling the rotary die when the temperature of the rotary die becomes equal to or higher than a set temperature. Production method.