JP2006317490A - Optical cable manufacturing method and optical cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical cable that can suppress increase, and to provide its manufacturing method. <P>SOLUTION: In manufacturing the optical cable 30, by arranging an aramid fiber 13 as a tension body on the outer circumference of a coated optical fiber 11, with a jacket 31 being extrusion-formed thereon, the aramid fiber 13 is heated by hot air before it is arranged on the outer circumference. Here, the surface temperature of the aramid fiber 13 is set to be not lower than 220°C and not higher than its thermal cracking start temperature. As a result, the oil content contained in the aramid fiber 13 is dissolved, without causing thermal cracks of the fiber 13 and uniformized in the circumferential or longitudinal direction, with the oil content in the surface layer being removed through vaporization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical cable manufacturing method and an optical cable, and more particularly to an optical cable manufacturing method and an optical cable in which an aramid fiber is arranged on the outer periphery of an optical fiber core and a jacket made of a plastic material is provided on the outer periphery.

2. Description of the Related Art Conventionally, there has been disclosed an optical cable manufacturing method in which a tensile body is provided on the outer periphery of a supplied optical fiber core and an outer cable is extruded on the outer periphery to manufacture an optical cable (see, for example, Patent Document 1).
As shown in FIG. 4, in the optical cable manufacturing apparatus 100, the single-core optical fiber cores 102a and 102b supplied from the optical fiber core supply reels 101a and 101b, and the tensile strength supplied from the strength member supply reels 103a and 103b. The bodies 104a and 104b are preheated together by the preheaters 105a and 105b. In the extruder 106, the preheated single-core optical fiber cores 102a and 102b and the tensile members 104a and 104b are inserted into points so that the coating resin is extruded and coated, and the cord type optical cable 107 is formed. Manufactured. The manufactured cord type optical cable 107 is taken up by a take-up machine 108 and taken up by a take-up reel 109.
Thus, the cord type optical cable manufactured by preheating the single-core optical fiber cores 102a and 102b and the strength members 104a and 104b and reducing the temperature difference from the point of the extruder 106 to be inserted into the point. The inner surface of the coating 107 is prevented from being uneven.
JP-A-11-174291

  By the way, although aramid fibers may be used as the tensile body, the aramid fibers include a bundling material whose main component is an oil that solidifies at room temperature, such as paraffin, so that the fibers are not scattered and entangled during manufacturing. It has been applied. In this case, if the oil content of the aramid fiber is not uniform in the circumferential direction and the longitudinal direction, the aramid fiber moves with the jacket and concentrates on the slackened aramid fiber immediately after production and when the jacket shrinks over time Can cause uneven pooling. For this reason, the optical fiber core wire is pressed and the contact force distribution is not uniform, and the transmission loss is increased by the microbend, so that there is a disadvantage that the transmission loss gradually increases with time from immediately after manufacture.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optical cable manufacturing method and an optical cable that can suppress an increase in transmission loss.

  In order to achieve the above-described object, the first feature of the optical cable manufacturing method according to the present invention is that an aramid fiber is disposed on the outer periphery of the optical fiber core wire supplied from the supply device, and the outer periphery is made of a plastic material. A method of manufacturing an optical cable in which an outer cover is extrusion-coated, wherein the surface temperature is 220 ° C. or more at a position after the aramid fiber bundle is unwound from a reel and before being arranged on the outer periphery of the optical fiber core wire. Heat with hot air so that the thermal decomposition start temperature of the aramid fiber to be used is lower than, and place the heated aramid fiber bundle on the outer periphery of the optical fiber core wire, plastic outer periphery of the aramid fiber bundle It has the process of carrying out extrusion coating of a jacket.

  In the optical cable manufacturing method configured as described above, an aramid fiber is disposed as a tensile body on the outer periphery of the optical fiber core, and an outer sheath is extruded on the outer periphery to manufacture an optical cable. Heat it with hot air before placing it on the outer periphery of the fiber core. At this time, since the temperature of the surface of the aramid fiber is 220 ° C. or more and not more than the thermal decomposition start temperature of the aramid fiber, the oil contained in the aramid fiber is dissolved without causing the aramid fiber to thermally decompose, or in the circumferential direction or It can be homogenized in the longitudinal direction, and the oil can be volatilized and removed from the surface layer. As a result, the oil content of the aramid fiber is made uniform, and the aramid fiber is in a dry and smooth state with a small amount of oil on the surface. Therefore, it is possible to prevent the transmission loss from gradually increasing immediately after the manufacturing due to the microbend accompanying the contraction of the outer cover.

  A second feature of the optical cable manufacturing method according to the present invention is that, in the first feature of the present invention, the temperature of the hot air is 600 ° C. or less.

  In the optical cable manufacturing method configured as described above, the thermal decomposition temperature of polyamide is 450 to 500 ° C., and the aramid fiber itself has a certain heat capacity. Therefore, the temperature of hot air at a level at which thermal decomposition does not occur is 600 ° C. Set as follows.

  According to a third aspect of the optical cable manufacturing method of the present invention, in the first or second aspect of the present invention, the highly elastic body has a function of suppressing contraction against contraction in the longitudinal direction of the jacket. Is provided in the jacket.

  In the optical cable manufacturing method configured as described above, the high elastic body suppresses the shrinkage of the outer jacket, and therefore it is possible to prevent an increase in transmission loss due to the microbend accompanying the shrinkage of the outer jacket.

  According to a fourth aspect of the optical cable manufacturing method of the present invention, in any one of the first to third aspects of the present invention, the optical fiber core wire includes a plurality of optical fibers arranged in parallel to form an ultraviolet curable resin. Therefore, the optical fiber tape is integrated.

  In the optical cable manufacturing method configured as described above, an optical fiber tape can be manufactured by using an aramid fiber as a tensile body and extruding the outer jacket with an ultraviolet curable resin.

  A fifth feature of the optical cable according to the present invention is that it is manufactured by the method for manufacturing an optical cable described in any one of the first to fourth features of the present invention.

  In the optical cable configured as described above, when an aramid fiber is disposed as a tensile body on the outer periphery of the optical fiber core and the outer cover is extruded and formed on the outer periphery to manufacture the optical cable, the aramid fiber is converted into the optical fiber core. By heating with hot air before placing it on the outer periphery of the fiber, it is possible to prevent the aramid fibers from accumulating unevenly and compressing the optical fiber, and also free to move against the shrinkage of the jacket after manufacture Since the degree is high, it is possible to prevent the outer casing from contracting due to contraction of the outer casing, so that it is possible to prevent the transmission loss from gradually increasing with time from immediately after manufacture.

  According to the present invention, when an aramid fiber is disposed as a tensile body on the outer periphery of an optical fiber core and an outer cable is extruded on the outer periphery to manufacture an optical cable, the aramid fiber is disposed on the outer periphery of the optical fiber core. Before heating, the oil component is volatilized by heating with hot air, so that an effect of preventing an increase in transmission loss with time and manufacturing an optical cable with stable characteristics can be obtained.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram showing a manufacturing apparatus to which an embodiment of an optical cable manufacturing method of the present invention is applied, FIG. 2 is a cross-sectional view showing an optical cable according to the present invention, and FIG. It is a graph which shows the relationship between the heating temperature of an aramid fiber, and transmission loss.

As shown in FIG. 1, in an optical cable manufacturing apparatus 10 that practices an optical cable manufacturing method according to an embodiment of the present invention, for example, eight optical fiber cores 11 are supplied upstream (left side in FIG. 1). A fiber supply 12 for supplying a tension member, an aramid fiber supply 14 for supplying an aramid fiber 13 as a tensile body, and a tension member supply 16 for supplying a tension member 15 such as FRP.
A hot air generator 20 is provided on the downstream side (right side in FIG. 1) of the aramid fiber supply 14, and the hot air is applied to the aramid fiber 13 supplied from the aramid fiber supply 14 and is included in the aramid fiber 13. Volatile oil is removed.

A collecting machine 17 for integrally forming an optical cable 30 as shown in FIG. 2 is provided on the downstream side of the hot air generator 20, the fiber supply 12, and the tension member supply 16. Therefore, the aramid fiber 13 is disposed on the outer periphery of the tape core wire 11 after being heated with hot air.
As shown in FIG. 2, in the optical cable 30, for example, an eight-core tape core wire 11 is disposed at the center, an aramid fiber 13 is disposed on the outer periphery of the tape core wire 11, and the tape core wire 11 is sandwiched therebetween. Tension members 15, 15 are arranged on both the left and right sides. And the whole is integrally covered with a jacket 31 made of PVC, for example.

Therefore, in the collecting machine 17, the aramid fiber 13 is arranged on the outer periphery of the supplied optical fiber 11, the tension member 15 is arranged at a predetermined position, and the outer jacket 31 is integrally formed on the outside by extrusion molding. The optical cable 30 is manufactured.
A cooling water tank 18 is provided on the downstream side of the collecting machine 17, and the optical cable 30 that is integrally formed by extrusion is cooled and wound by a winder 19 on the downstream side.

Next, the manufacturing method of the optical cable which is embodiment of this invention is demonstrated.
In the method for manufacturing an optical cable according to the present invention, an aramid fiber 13 is arranged on the outer periphery of a tape core wire 11 that is an optical fiber core wire supplied from a fiber supply 12 that is a supply device, and a jacket 31 made of a plastic material is provided on the outer periphery. Are extrusion coated. The surface temperature of the aramid fiber 13 is 220 ° C. or higher by the hot air generator 20 at a position after the aramid fiber 13 bundle is fed out from the aramid fiber supply 14 as a reel and before being arranged on the outer periphery of the tape core wire 11. And it heats with a hot air so that it may become below the thermal decomposition start temperature of the aramid fiber 13 to be used. And it has the process of arrange | positioning the aramid fiber 13 bundle | flux after heating to the outer periphery of the tape core wire 11, and extruding and coat | covering the plastic jacket 31 on the outer periphery of the aramid fiber 13 bundle | flux by the gathering machine 17. FIG.

In the hot air generator 20, it is desirable to control the hot air temperature so that it is 600 ° C. or lower as the thermal decomposition start temperature of the aramid fiber 13 or lower. That is, the thermal decomposition temperature of the polyamide is 450 to 500 ° C., and the aramid fiber itself has a certain heat capacity.
In addition, it is desirable that a tension member 15 such as FRP is provided in the jacket 31 as a highly elastic body having a function of suppressing the shrinkage in the longitudinal direction of the jacket 31. As a result, the tension member 15 suppresses the contraction of the outer cover 31, so that it is possible to prevent an increase in transmission loss due to the microbend accompanying the contraction of the outer cover 31.
The optical fiber core 11 can be an optical fiber tape in which a plurality of optical fibers 32 are arranged in parallel and integrated with a coating 33 of an ultraviolet curable resin.

Next, FIG. 3 shows the relationship between the heating temperature of the aramid fiber 13 and the change over time of the transmission loss of the optical cable 30 manufactured using the aramid fiber 13.
Here, an aramid fiber 13 is provided around an eight-core tape core (width 2.1 mm, thickness 0.32 mm) 11, a vinyl chloride resin is used for the jacket 31, and the inner dimension is 3.5 mm in width and thickness. Transmission loss was measured using an optical cable 30 integrally molded to 1.2 mm, a width of 4.5 mm, and a thickness of 2.6 mm.

As shown in FIG. 3, the transmission loss immediately after manufacture is approximately 0.25. However, when the optical cable 30 is manufactured by heating the aramid fiber 13 at a temperature from room temperature (that is, a temperature not heated) to 200 ° C. From the measurement of the transmission loss after 8 days from the manufacture, it can be seen that the transmission loss increases with time. When used at room temperature, the transmission loss is slightly higher immediately after manufacture due to the roughness of the inner surface of the point of the collecting machine 17, and thereafter, similarly, changes with time.
On the other hand, when the aramid fiber 13 is used after being heated at 220 ° C. or higher, it is found from the measurement of the transmission loss after 8 days that the transmission loss does not increase immediately after production.

  As described above, according to the optical cable manufacturing method and the optical cable 30 described above, when the aramid fiber 13 is arranged as a tensile body on the outer periphery of the optical fiber core and the outer cover 31 is extruded and formed on the outer periphery, the optical cable 30 is manufactured. The aramid fiber 13 is heated with hot air before being disposed on the outer periphery of the tape core wire 11. At this time, since the temperature of the surface of the aramid fiber 13 is 220 ° C. or higher and not higher than the thermal decomposition start temperature of the aramid fiber 13, the contained oil component is dissolved without thermally decomposing the aramid fiber 13, or the circumferential direction or It can be homogenized in the longitudinal direction and volatilized and removed from the surface layer. As a result, the oil content of the aramid fiber 13 is made uniform, and the aramid fiber 13 is in a dry and smooth state with a small amount of oil on the surface. Therefore, it is possible to prevent the outer shell 33 from contracting due to the contraction of the outer shell 33. Therefore, it is possible to prevent the transmission loss from gradually increasing with time due to the microbend accompanying the contraction of the outer shell 33. It will be possible.

The optical cable manufacturing method and the optical cable of the present invention are not limited to the above-described embodiments, and appropriate modifications, improvements, and the like are possible.
For example, in the above-described embodiment, the 8-core tape core 11 is used as the optical fiber core, but the number of cores is not limited to this. Further, the present invention can be similarly applied even when a single-core optical fiber is used.

  As described above, the optical cable manufacturing method and the optical cable according to the present invention are arranged when an aramid fiber is disposed as a tensile body on the outer periphery of the optical fiber core, and an outer cover is extruded on the outer periphery to manufacture an optical cable. Before placing the aramid fiber on the outer periphery of the optical fiber core, it is heated with hot air to volatilize the oil component, thereby preventing an increase in transmission loss over time and producing an optical cable with stable characteristics. It is useful as an optical cable manufacturing method, an optical cable, and the like in which an aramid fiber is arranged on the outer periphery of an optical fiber core and an outer sheath made of a plastic material is provided on the outer periphery.

It is a block diagram which shows the manufacturing apparatus which applies embodiment which concerns on the manufacturing method of the optical cable of this invention. It is sectional drawing which shows the optical cable which concerns on this invention. It is a graph which shows the relationship between the heating temperature of an aramid fiber and transmission loss in the 8th day after manufacture immediately after manufacture. It is a block diagram which shows the manufacturing apparatus by the manufacturing method of the conventional optical cable.

Explanation of symbols

11 Tape core (optical fiber core)
12 Fiber supply (supply equipment)
13 Aramid fiber 14 Aramid fiber supply (reel)
15 Tension member (high elastic body)
30 Optical cable 31 Jacket

Claims (5)

A method for producing an optical cable in which an aramid fiber is disposed on an outer periphery of an optical fiber core wire supplied from a supply device, and an outer sheath made of a plastic material is extruded and coated on the outer periphery,
After the aramid fiber bundle is unwound from the reel and before being disposed on the outer periphery of the optical fiber core wire, the surface temperature is 220 ° C. or higher and the thermal decomposition start temperature of the aramid fiber to be used is lower. Heated with hot air,
Arranging the heated aramid fiber bundle on the outer periphery of the optical fiber core,
A method for producing an optical cable, comprising a step of extruding and covering a plastic outer cover on the outer periphery of the aramid fiber bundle.   The method of manufacturing an optical cable according to claim 1, wherein the temperature of the hot air is 600 ° C. or less.   The method of manufacturing an optical cable according to claim 1 or 2, wherein a high-elasticity body having a function of suppressing contraction against contraction in a longitudinal direction of the jacket is provided in the jacket.   The optical fiber manufacturing method according to any one of claims 1 to 3, wherein the optical fiber core is an optical fiber tape in which a plurality of optical fibers are integrated in parallel by an ultraviolet curable resin.   An optical cable manufactured by the method for manufacturing an optical cable according to any one of claims 1 to 4.

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