JP2002023030A - Manufacturing method of optical cable for strain sensing - Google Patents

Abstract

(57) [Problem] To provide a method of manufacturing an optical cable for strain sensing that has excellent adhesion to an embedded object such as a concrete structure and is easy to manufacture. An uneven structure is provided on the outer surface of an extrusion coating layer (4) of a strain sensing optical cable (1). When the optical cable (1) is buried in a concrete structure or soil, concrete (cement particles, earth and sand, etc.) is placed in a concave portion. Since it enters (the convex portion is buried in the concrete), the adhesion between the optical cable 1 and the buried object is improved. By providing the reinforced coating layer 3 between the optical fiber 2 and the extruded coating layer 4, the optical fiber 2 can withstand the impact even when the concrete is cast, and even if the concrete is cracked. No damage occurs to the optical fiber 2.

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 an optical cable for strain sensing, which is used by embedding it in a concrete structure such as a building, a bridge, a tunnel or the like, or embankment of a river or a slope of a mountain.

[0002]

2. Description of the Related Art In recent years, optical fibers are buried linearly or in loops in concrete structures such as buildings, bridges, and tunnels, or in soils such as river embankments and mountain slopes, and light is propagated through the optical fibers. As a result, a method for measuring the strain of each structure online has been developed.

[0003] However, since ordinary communication optical fibers are used as this kind of optical fiber for strain sensing, they are easily broken and have poor handling properties when buried in a concrete structure or soil. There was a problem.

Therefore, as a method for solving such a problem, for example, a structure in which a reinforcing fiber is longitudinally added to the outer periphery of an optical fiber and a reinforcing coating layer (FRP) in which the reinforcing fiber is integrated with a matrix resin is provided. An optical cable for strain sensing can be considered.

[0005]

However, the FRP
Although the optical cable for strain sensing having the structure provided with the structure improves the handleability at the time of burying construction, if the outermost layer surface is smooth, there is a new problem that the degree of adhesion to the concrete structure or the soil is low.

In order to improve the fixing (adhesion) with concrete, for example, a structure in which the outer diameter is varied in the longitudinal direction of the reinforced coating layer, a structure in which a thread or the like is wound around the reinforced coating layer, and the like are conceivable. .

However, it is difficult to manufacture a product having a variable outer diameter, and an extra reinforcing fiber is required to secure the tensile performance. As a result, the product diameter increases. In addition, for wound products, there is a problem that if the adhesion between the yarn and the reinforced coating layer is not sufficient, the adhesion is eventually weakened.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method of manufacturing an optical cable for strain sensing which has excellent adhesion to an object to be buried such as a concrete structure and is easy to manufacture. It is in.

[0009]

In order to achieve the above object, a method of manufacturing an optical cable for strain sensing according to the present invention comprises:
A plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin are wound around the outer periphery of the optical fiber to form a reinforced coating layer, and the molten thermoplastic resin is extruded around the reinforced coating layer and extruded. Forming a coating layer, cooling and curing the extruded coating layer, and then heating and curing the reinforced coating layer to form a strain sensing optical cable integrated with the extruded coating layer. After
A concave portion is formed on the surface of the extruded coating layer by allowing the surface of the extruded coating layer to pass through rollers having convex portions formed at regular intervals in a state where the surface of the extruded coating layer is softened.

The method of manufacturing an optical cable for strain sensing according to the present invention comprises the steps of: forming a reinforcing coating layer by winding a plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin around the outer periphery of an optical fiber; A molten thermoplastic resin is extruded on the outer periphery of the layer to form an extruded coating layer, and the extruded coating layer is cooled and cured, and then heated to cure the reinforced coating layer and integrated with the extruded coating layer. In the method for manufacturing an optical cable for strain sensing, after the hardening of the reinforcing coating layer, an outer coating layer having an uneven structure composed of a plurality of spiral ribs on the outer surface is formed on the outer periphery of the extruded coating layer.

In the method of manufacturing an optical cable for strain sensing according to the present invention, a plurality of reinforcing fibers having a sheath-core structure having a core and a sheath having a lower melting point than the core are longitudinally attached to the outer periphery of the optical fiber. Then, only the sheath portion is melted and then cured to form a reinforced coating layer, and an extruded coating layer having a plurality of uneven structures on the surface is formed on the outer periphery of the reinforced coating layer.

In the method of manufacturing an optical cable for strain sensing according to the present invention, a plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin are wound around the outer periphery of an optical fiber and drawn by a die having an irregular cross section. Forming an uneven structure consisting of a plurality of spiral ribs on the outer surface of the reinforced reinforcing layer by forming a reinforced reinforcing layer by heating and curing the thermosetting resin while applying twist with a rotary take-up machine It is.

According to the present invention, an uneven structure is provided on the outer surface of the extrusion coating layer of the optical cable for strain sensing. When this optical cable is buried in a concrete structure or soil, concrete (cement particles, earth and sand, etc.) )
(The convex portion is buried in the concrete), so that the adhesion between the optical cable and the object to be buried is improved.

Further, according to the present invention, by providing the reinforced coating layer between the optical fiber and the coating layer, the optical fiber can withstand the impact even at the time of concrete casting. Even if the concrete cracks, the optical fiber is hardly damaged.

On the other hand, for the extrusion coating layer, any thermoplastic resin may be used as long as it has alkali resistance.
In order to accurately detect distortion of a concrete structure or the like, it is desirable that the reinforcing structure be firmly adhered to the reinforced coating layer.

As a method of improving such adhesion,
It is effective to use a thermoplastic resin having high chemical affinity with the reinforced coating layer, and as such a thermoplastic resin,
PSU (diphenylsulfone-bisphenol A copolymer), ABS (acrylonitrile-butadiene-styrene copolymer), AAS (acrylonitrile-acryl rubber-styrene copolymer), AES (acrylonitrile-EPDM rubber-styrene copolymer) Polymer) and modified PPE (polyphenylene ether modified with polystyrene).

As another method for improving the adhesion, the temperature in the curing tank at the time of curing the matrix resin of the reinforced coating layer is set to a temperature near the melting point of the thermoplastic resin of the extruded coating layer, for example, nylon 12 In the case of, 160-1
90 ° C, 120-160 ° C for polyethylene
And 160 to 190 ° C. in the case of polypropylene.

When the reaction of the uncured matrix resin in the reinforced coating layer starts under such a temperature condition, the interface between the thermoplastic resin and the reinforced coating layer is heated by the heat generated by the curing of the matrix resin. And the inner peripheral portion of the thermoplastic resin at the interface is melted, whereby the reinforced coating layer and the thermoplastic resin layer firmly adhere to each other due to the anchor effect under a pressurized atmosphere.

The reinforcing fibers of the reinforced coating layer include glass fibers,
Aramid fiber, polyarylate fiber, polybenzobisoxazole fiber, carbon fiber, polyolefin fiber,
Stainless steel fibers can be used.

When an unsaturated polyester resin containing a styrene-based compound as a monomer is used as the matrix resin for integrating the reinforcing fibers, the styrene monomer permeates the buffer coating of the optical fiber and the transmission characteristics deteriorate. For example, unsaturated polyester resins, vinyl ester resins, urethane acrylate resins, and the like, in which the polymerizable monomer is a non-styrene compound, are desirable.

When a thermoplastic resin such as a polyolefin fiber is used as the reinforcing fiber, a thermoplastic resin having a lower melting point than the reinforcing fiber can be used. For example, a polypropylene resin can be used as a reinforcing fiber and a polyethylene resin can be used as a matrix resin.

In the above-mentioned uneven structure, the grooves formed in the direction perpendicular to the longitudinal direction of the extruded coating layer are formed by forming the grooves in the shape of the uneven intermittently formed at predetermined intervals along the longitudinal direction of the reinforced coating layer. Can be configured.

Further, the concavo-convex structure may be constituted by providing an outer coating layer having two or more spiral ribs formed on the extruded coating layer. The spiral traveling angle α can be set to 5 ° or more.

[0024]

[Formula 1] (Rib outer diameter × π) ÷ Twist pitch = tan α According to this configuration, the degree of adhesion to concrete is further improved by setting the spiral advancing angle α so as to satisfy Formula 1. be able to. The spiral ribs
SZ spiral ribs in which the traveling direction is alternately reversed every predetermined rotation angle may be used.

Further, according to the present invention, the reinforcing coating layer comprises:
It is composed of a matrix resin with high light transmittance including ultraviolet and visible light and reinforcing fibers, and the uneven structure is composed of two or more spiral ribs formed on the reinforced coating layer. The angle α can be set to 5 ° or more.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an optical cable for strain sensing according to the present invention will be described below.

According to the method of manufacturing an optical cable for strain sensing, a plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin are wound around the outer periphery of an optical fiber to form a reinforced coating layer. When extruding a thermoplastic resin melted on the outer periphery to form an extruded coating layer, only the surface of the thermoplastic resin layer is softened, and is inserted at regular intervals between rollers having convex portions formed thereon. Thereby, embossing is performed, and the reinforced coating layer and the extrusion coating layer are integrated by cooling and curing.

According to the present optical cable for sensing, an uneven structure is provided on the outer surface of the reinforcing coating layer of the optical cable for strain sensing. When this optical cable is buried in a concrete structure or soil, the uneven structure portion is embedded in the concrete. Since cement particles, earth and sand, etc. enter, the adhesion between the optical cable and the object to be buried is improved.

[0029]

Next, the present invention will be described with reference to specific numerical values, but the present invention is not limited thereto.

(Example 1) FIG. 1A is a plan view showing an example of an optical cable to which a method for manufacturing an optical cable for strain sensing according to the present invention is applied, and FIG.
1A is a cross-sectional view taken along a line BB in FIG. 1A.

The strain sensing optical cable 1 comprises an optical fiber 2, a reinforced coating layer 3 formed on the outer periphery of the optical fiber 2, and an extruded coating layer 4 formed on the outer periphery of the reinforced coating 3. It is composed of

The reinforced coating layer 3 is cut in the longitudinal direction by a plurality of reinforcing fibers 5 longitudinally attached along the longitudinal direction of the optical fiber 2 and a matrix resin 6 which integrally combines the reinforcing fibers 5. It is configured so that the change in area is small.

The extrusion coating layer 4 is made of a thermoplastic resin,
On the outer surface, a concavo-convex structure composed of embossments 7 having concavo-convex shape is formed. The uneven emboss 7 is formed by the extrusion coating layer 4.
Are formed intermittently at predetermined intervals P along the longitudinal direction of the extruded coating layer 4 so as to extend in a direction perpendicular to the longitudinal direction of the extruded coating layer 4.

According to the optical cable 1 for strain sensing constructed as described above, since the outer surface of the extruded coating layer 4 is provided with the concave-convex structure composed of the concave-convex emboss 7, the optical cable 1 is used as a concrete structure or a concrete structure. When buried in the soil, cement particles and earth and sand in the concrete enter into the groove 8 having the concave cross section, so that the adhesion between the optical cable 1 and these buried objects is improved.

Further, by providing the reinforcing coating layer 3,
Even when concrete is cast, the optical fiber 2 can withstand the impact, and even if cracks occur in the concrete, the optical fiber 2 is not damaged.

Next, a method of manufacturing the optical cable shown in FIGS. 1A to 1C will be described.

As the reinforcing fiber 5, aramid fiber 1560
dtex (manufactured by Toray DuPont: Kevlar 49)
Are used. A vinyl ester resin made of a non-styrene monomer polymer containing a peroxide catalyst as a matrix resin in the aramid fiber (manufactured by Mitsui Chemicals, Inc .:
Ester H2000HV) impregnated with φ0.25mm
Along with the outer circumference of the optical fiber 2 described above, a nozzle having an inner diameter of 1.6 mm is used to form a drawn cable.

After molding into a cable shape, it is led to the head of the melt extruder, and an LLDPE resin (manufactured by Nippon Unicar: NUCG530) is formed around the outer periphery of the cable-like molded body as a resin for molding the extrusion coating layer 4 from the die. Then, the resin is coated so as to have an outer diameter of 3.0 mm, and cooled immediately after the coating, whereby an uncured intermediate molded product of the matrix resin 6 is obtained.

Next, the intermediate molded product was taken into a 12 m-long heat-curing tank filled with high-pressure steam at 145 ° C. at a take-off speed of 15 m / m.
In this case, an optical cable intermediate having a substantially circular cross section having an outer diameter of 3.0 mm and an FRP outer diameter of 1.6 mm is obtained by curing the matrix resin 6 by guiding the same.

Further, the optical cable intermediate was guided to a heating device having a bath length of 200 mm, which was adjusted to 300 ° C. using hot air as a medium at a take-up speed of 7 m / min, to soften only the surface of the extrusion coating layer 4 (LLDPE). The resin is melted), and a pair of rollers having a pair of upper and lower, left and right, with convexes formed at regular intervals on the outer circumference, a total of four rollers are arranged, and the maximum outer diameter of the convexes is inserted by inserting the rollers. Is 3.4 mm, the depth of the groove 8 having a concave cross section is 0.3 mm, and the pitch P is 10 mm.
The optical cable 1 having the uneven embossment formed on the outer periphery is obtained. Table 1 shows the performance of the optical cable 1 thus obtained.

[0041]

[Table 1]

(Embodiment 2) FIG. 2 is a sectional view showing another embodiment of an optical cable to which the method for manufacturing a strain sensing optical cable according to the present invention is applied.

The present optical cable 10a is an optical fiber 1
1a, a reinforced coating layer 12a formed on the outer periphery of the optical fiber strand 11a, and an extruded coating layer 13a formed on the outer periphery of the reinforced coating layer 12a.

The reinforcing coating layer 12a is formed of the optical fiber 11
a plurality of reinforcing fibers 1 longitudinally attached along the longitudinal direction of a
20a and a matrix resin 121a that integrally integrates the reinforcing fibers 120a are configured so that a change in cross-sectional area in the longitudinal direction is reduced.

The extruded coating layer 13a is made of a thermoplastic resin, and is composed of an inner coating layer 130a and an outer coating layer 131a.

On the outer surface of the outer covering layer 131a, four (four, but not limited to, four) spiral ribs 1 are shown.
An uneven structure made of 4a is formed. The spiral rib 14a is arranged in a spiral shape that rotates in one direction.

The same effect as in the first embodiment can be obtained in the optical cable 10a for strain sensing configured as described above.

Next, a method of manufacturing the optical cable shown in FIG. 2 will be described.

The aramid fiber 15 is used as the reinforcing fiber 120a.
60dtex (manufactured by Toray DuPont: Kevlar 4)
Use 9). The aramid fiber is impregnated with a vinyl ester resin (Ester H2000HV, manufactured by Mitsui Chemicals, Inc.) made of a non-styrene monomer polymer containing a peroxide catalyst as the matrix resin 121a.
Attached to the outer circumference of an optical fiber of 0.25 mm in inner diameter.
A cable-shaped molded body is formed by drawing with a 6 mm nozzle. This cable-shaped molded body is guided to the head of a melt extruder, and LLDPE resin (manufactured by Nippon Unicar: NUCG53) is used as a resin for forming the inner coating layer 130a on the outer periphery.
50) is extruded annularly from a die to cover an outer diameter of 2.6 mm, and immediately cooled to obtain an uncured material having an inner coating layer 130a.

Next, the uncured product was taken into a 12 m-long heat-curing tank filled with high-pressure steam at 145 ° C. at a take-off speed of 15 m / m.
In this case, an optical cable intermediate having a substantially circular cross section having an outer diameter of 2.6 mm and an FRP outer diameter of 1.6 mm is obtained by curing the matrix resin 121a.

Further, while preliminarily heating this optical cable intermediate to 60 ° C., it was guided to a rotating die at a take-up speed of 7 m / min, and an HDPE resin (manufactured by Mitsui Chemical: Hizex 6600M) was rotated as a resin for forming the outer coating layer 131a. By extruding at 200 ° C. while rotating the die in one direction, the outer diameter is 3.8 mm, the number of ribs is 4, the rib height is 0.5 mm,
An optical cable having a helical rib 14a with a twist pitch of 125 mm is obtained.

The optical cable 10a having a length of 50 m thus obtained is put into a container, and the concrete is cast to a depth of 50 cm. The transmission performance is 1.0 dB / km or less, the tensile breaking strength is 3400 N, Tensile modulus 588
00MPa and concrete adhesion were 1000N.

The adhesive strength of the concrete was adjusted by mixing one end of the obtained optical cable 10a with concrete (manufactured by Toyo Materan Co., Ltd .: instant cement with 20% of water) so that the fixing length became 70 mm. Did)
Using a sample which was left and cured at 23 ± 5 ° C. for 7 days using a tensile tester (Instron TCM-5000C), the drawing speed was 5 mm / mi.
The maximum pulling force when the pulling force was measured in n was defined as the adhesion force. These results are set forth in Table 1.

(Embodiment 3) FIG. 3 is a sectional view showing another embodiment of an optical cable to which the method for manufacturing a strain sensing optical cable according to the present invention is applied.

The present optical cable 10b is an optical fiber 1
1b, a reinforced coating layer 12b formed on the outer periphery of the optical fiber 11b, and an extruded coating layer 13b formed on the outer periphery of the reinforced coating layer 12b.

The reinforced covering layer 12b is made of a reinforcing fiber 120b.
And a matrix resin 121b that integrally integrates the reinforcing fibers 120b.

The extruded coating layer 13b is made of a thermoplastic resin and has an inner / outer two-layer structure of an inner coating layer 130b and an outer coating layer 131b.

On the outer surface of the outer coating layer 131b, four spiral ribs 14b (the number is not limited to four in the figure).
Is formed. This spiral rib 1
4b is an S in which the traveling direction is alternately reversed at a predetermined rotation angle.
It is a Z-shaped spiral rib. The optical cable 10b configured as described above has the same effects as those of the first embodiment.

Next, a method of manufacturing the optical cable shown in FIG. 3 will be described.

The difference from the method for manufacturing the optical cable 10a shown in FIG. 2 is that the rotation direction of the rotary die is set to a reversal angle of 360 °.
This is a point where the reversal pitch is set to 125 mm and reversed. The other points are the same as the method of manufacturing the optical cable 10a shown in FIG.

In this embodiment, an optical cable 10b having SZ-shaped spiral ribs is obtained.

At this time, the spiral advancing angle α approximated by the equation (2) is set to 5.5 ° or more.

[0063]

Tan α = (rib outer diameter × π × reversal angle ÷ 36)
0) Twist pitch The performance of the obtained optical cable 10b is shown in Table 1.

(Embodiment 4) FIG. 4 is a sectional view showing another embodiment of an optical cable to which the method for manufacturing an optical cable for strain sensing of the present invention is applied.

The present optical cable 10c is an optical fiber 1
1c, a reinforced coating layer 12c formed on the outer periphery of the optical fiber strand 11c, and an extruded coating layer 13c formed on the outer periphery of the reinforced coating layer 12c.

The reinforcing coating layer 12c is made of P having a sheath-core structure.
It is made of E / PP (polyethylene / polypropylene) fiber.

The extruded coating layer 13c is made of a thermoplastic resin, and has an inner and outer two-layer structure of an inner coating layer 130c and an outer coating layer 131c.

On the outer surface of the outer coating layer 131c, an uneven structure composed of four spiral ribs 14c is formed.
The spiral rib 14c of the present embodiment is configured to advance in one direction, as in the second embodiment. The optical cable 10c configured as described above can provide the same effects as those of the first embodiment.

Next, a method for manufacturing the present optical cable will be described.

PE / PP fiber (sheath part PE, core part PP) having a sheath-core structure on the outer periphery of the optical fiber 11c (UC fiber manufactured by Ube Nitto Kasei Co., Ltd.) 2200 dtex × 1
No optical fiber 11 through a guide plate (not shown).
c is the temperature at which only the sheath melts vertically along the outer circumference of c.
FRT by passing it through a metal molding nozzle with an inner diameter of 2.0 mm set at a temperature of 60 ° C. at a take-up speed of 2 mm / min.
A P-coated optical fiber is obtained.

Next, the LLDPE resin is extruded from the die and coated in an annular shape with an outer diameter of 2.6 mm to obtain an optical cable intermediate having a coating outer diameter of 2.6 mm and an FRTP outer diameter of 2.0 mm and a substantially circular cross section. .

Further, the optical cable intermediate was used in Example 2.
The outer diameter is 3.8 mm, the number of ribs is 4, the rib height is 0.5 mm,
An optical cable 10c having a helical rib 14c with a twist pitch of 125 mm is obtained. Obtained optical cable 10
The performance of c is shown in Table 1.

(Embodiment 5) FIG. 5 is a sectional view showing another embodiment of an optical cable to which the method for manufacturing an optical cable for strain sensing of the present invention is applied.

The optical cable 10d is an optical fiber 1
1d and a reinforced coating layer 12d formed on the outer periphery of the optical fiber strand 11d.

The reinforcing coating layer 12 d is formed of a plurality of reinforcing fibers 12.
0d and a matrix resin 121d that integrally integrates the reinforcing fibers 120d, and has an uneven structure formed of four spiral ribs 14d on the outer surface.

The spiral rib 14d is configured to travel in one direction, similarly to the optical cable 10a of the first embodiment.

The thus obtained optical cable 10d
The same effect as in the first embodiment can be obtained.

Next, a method for manufacturing the optical cable will be described.

The glass fiber 30 is used as the reinforcing fiber 120d.
Use 17 8dtex. This glass fiber is impregnated with a vinyl ester resin (manufactured by Mitsui Chemicals, Inc .: Ester H2000HV) composed of a non-styrene monomer polymer containing a photopolymerization initiator as a matrix resin 121d.
By vertically applying the outer circumference of a 0.25 mm optical fiber 11d and drawing by a die having an irregular cross-sectional shape, UV irradiation was performed by an ultraviolet irradiation device while applying twisting by a rotary pulling machine. An optical cable 10d having a spiral rib 14d having the same outer diameter and twist size is obtained. The performance of the obtained optical cable 10d is shown in Table 1.

Comparative Example 1 FIG. 6 is a sectional view showing a comparative example of an optical cable to which a conventional manufacturing method is applied.

The optical cable 10e has no protective coating layer on the outer layer, and has a protective layer 20 made of an ultraviolet curable resin formed on the outer periphery of the optical fiber 11e.

When an attempt was made to measure the concrete pulling force using the optical cable 10e, the optical fiber 11e was broken by a pulling force of 4N. When the 50 m optical cable 10 e was embedded in concrete having a depth of 50 cm, the transmission loss value was greatly reduced to 12 dB / km.

Table 2 shows the performance of the comparative example.

[0084]

[Table 2]

(Comparative Example 2) FIG. 7 is a cross-sectional view showing a comparative example of an optical cable to which another conventional manufacturing method is applied.

In the same manner as in Example 2, the reinforced coating layer 12
An optical cable 10f having an outer diameter of 1.6 mm, an outer diameter of the extrusion coating layer 13f of 2.6 mm, and a substantially circular cross-sectional shape was produced. The concrete adhesion of the optical cable 10f was measured and found to be as low as 240N.

(Comparative Example 3) Under the same conditions as in Example 2, except that the outermost layer coating was performed in a state where the rotary die did not rotate.
The outer diameter of the extruded coating layer is 3.8 mm and the outer surface is smooth.
A straight optical cable as shown in FIG. When we measured the concrete adhesion of this optical cable,
The value was as low as 300N.

[0088]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a method for manufacturing an optical cable for strain sensing which has excellent adhesion to an object to be buried such as a concrete structure and is easy to manufacture.

[Brief description of the drawings]

1A is a plan view showing an example of an optical cable to which a method for manufacturing an optical cable for strain sensing according to the present invention is applied, FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A, and FIG. a)
FIG. 7 is a sectional view taken along line BB of FIG.

FIG. 2 is a cross-sectional view showing another embodiment of the optical cable to which the method for manufacturing a strain sensing optical cable according to the present invention is applied.

FIG. 3 is a cross-sectional view showing another embodiment of the optical cable to which the method for manufacturing a strain sensing optical cable according to the present invention is applied.

FIG. 4 is a cross-sectional view showing another embodiment of the optical cable to which the method of manufacturing the optical cable for strain sensing of the present invention is applied.

FIG. 5 is a cross-sectional view showing another embodiment of the optical cable to which the method of manufacturing the optical cable for strain sensing of the present invention is applied.

FIG. 6 is a sectional view showing a comparative example of an optical cable to which a conventional manufacturing method is applied.

FIG. 7 is a cross-sectional view showing a comparative example of an optical cable to which another conventional manufacturing method is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Strain sensing optical cable (optical cable) 2 Optical fiber strand 3 Reinforcement coating layer 4 Extrusion coating layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshinobu Kurosawa 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Within the Opto-System Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Shigehiro Endo Hidaka-cho, Hitachi City, Ibaraki Prefecture 5-1-1, Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Hiroshige Ono 2-3-1, Otemachi, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Hiroshi Naruse Tokyo 2-3-1, Otemachi, Chiyoda-ku Nippon Telegraph and Telephone Corporation (72) Inventor Hitoshi Kumagai 2-3-2 Shibaura, Minato-ku, Tokyo Shimizu Corporation F-term (reference) 2H001 BB06 BB28 DD07 DD11 DD25 KK17 KK23 MM01 MM05 2H050 AD06 BA01 BA02 BB10S BB20R BB32R BB35S BC03 BC17 BC18

Claims (4)

[Claims] 1. A reinforcing resin layer is formed by winding a plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin around an outer periphery of an optical fiber, and a thermoplastic resin melted around the outer periphery of the reinforcing coating layer. Extrusion molding to form an extruded coating layer, cooling and curing the extruded coating layer, and then heating to cure the reinforced coating layer and integrate with the extruded coating layer to produce an optical cable for strain sensing. In the method, after curing the reinforced coating layer, the surface of the extruded coating layer is inserted between rollers having convex portions formed at regular intervals in a state where the surface of the extruded coating layer is softened. A method for manufacturing an optical cable for strain sensing, comprising forming a concave portion in the optical fiber. 2. A reinforced coating layer formed by winding a plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin around an outer periphery of an optical fiber, forming a reinforced coating layer, and a molten thermoplastic resin around the outer periphery of the reinforced coating layer. Extrusion molding to form an extruded coating layer, cooling and curing the extruded coating layer, and then heating to cure the reinforced coating layer and integrate with the extruded coating layer to produce an optical cable for strain sensing. In the method, after curing the reinforcing coating layer, an outer coating layer having an uneven structure formed of a plurality of spiral ribs on an outer surface is formed on an outer periphery of the extruded coating layer, for strain sensing. Optical cable manufacturing method. 3. A plurality of reinforcing fibers having a sheath-core structure having a core and a sheath having a lower melting point than the core are longitudinally added to the outer periphery of the optical fiber, and only the sheath is melted. A method for producing an optical cable for strain sensing, comprising: forming a reinforced coating layer by post-curing; and forming an extruded coating layer having a plurality of uneven structures on the surface on the outer periphery of the reinforced coating layer. 4. A plurality of reinforcing fibers impregnated with an uncured thermosetting matrix resin are wound around the outer periphery of an optical fiber, drawn by a die having a modified cross section, and then heated while being twisted by a rotary take-up machine. Forming a reinforced reinforcing layer by curing the thermosetting resin, thereby forming an uneven structure including a plurality of spiral ribs on an outer surface of the reinforced reinforcing layer. Manufacturing method.