JPH11165324A - Method for embedding optical fiber for epoxy cast article, and its embedded cast article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cast by embedding surely easily an optical fiber in an epoxy resin by a method wherein an optical fiber strain sensor is embedded in any central part of a round dumbbell test piece of an epoxy resin cast article, and casting is executed. SOLUTION: A fiber 3 is fixed by being put in a notch of a rubber stopper 2. A sensor part 3a is provided at a center part of the fiber 3. As the sensor part 3a, for example, a strain sensor, a color sensor, a temperature sensor, an acceleration sensor, a pressure sensor, etc., can be used. Successively an upper part of the fiber 3 is fastened with a clip 4, and the fiber is fixed under a state of being stretched tight by applying lightly tensile strength. An epoxy resin is casted into a mold 1 under a state wherein the fiber 3 is fixed, and cured to prepare a test piece forming a dumbbell shape. Further, an upper end of the fiber 3 set free in an upper part of the mold is connected to a connector 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for embedding an optical fiber in an epoxy casting and an embedded casting.

[0002]

2. Description of the Related Art At present, epoxy molding is widely used for insulating high-voltage equipment such as power switches and circuit breakers.
Here, the epoxy degrades over time under the influence of heat, light, moisture and the like. Although there are many studies on the degradation behavior of epoxy resins, a method for accurately knowing the state inside the resin has not yet been developed.

FIG. 2 shows a commercially available fiber sensor. As shown in the figure, a sensor part 02 such as a grating is processed in the middle or at the tip of the fiber 01, and the sensor part 02 is embedded in an object to be measured (not shown), and the connector 03 is connected to a measuring device (not shown). Various physical quantities can be measured. The measuring device measures light intensity, phase, and the like, and generally functions as a light source.

[0004]

When the above-mentioned sensors are embedded in an epoxy mold, there are the following problems. Since the component is used under a high voltage, electric, magnetic, electromagnetic or the like cannot be used as a signal of the sensor. The sensor itself needs to be an insulator so as not to impair the insulation performance. It is difficult to fix the sensor at an arbitrary position inside the resin.

[0005]

SUMMARY OF THE INVENTION The present invention enables an optical fiber strain sensor to be embedded in an epoxy resin cast product, for example, a round dumbbell test piece at an arbitrary central portion. An optical fiber uses light as a signal, is not affected by a high electric field, and has a characteristic that the optical fiber itself is an insulator.

The fiber embedding method of the present invention can be applied to not only strain sensors but also any kind of fiber sensors. For example, by processing a fiber into a sensor before embedding, it is possible to measure the state inside the epoxy such as strain, temperature, and color.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below for each fiber fixing method. Embodiment 1 FIG. 1 shows a first embodiment of the present invention. In this embodiment, an optical fiber is embedded in a dumbbell-type epoxy cast product.

First, a rubber stopper 2 having a cut is placed in the center of the lower surface of a dumbbell mold 1. Dumbbell mold 1
Is a mold having a cavity in which the inside diameter of the intermediate portion is small and constant, and the inside diameter is widened upward and downward. As shown in FIG. 3, the rubber stopper 2 has a cylindrical shape whose outer diameter increases as it goes downward, and has a cut 2a for passing the fiber 3 in the center thereof.

Next, the fiber 3 is sandwiched and fixed in the cut 2a of the rubber stopper 2. In the center of the fiber 3 is the sensor 3
a is provided. As the sensor unit 3a, for example, a strain sensor, a color sensor, a temperature sensor, an acceleration sensor, a pressure sensor, or the like can be used. Continue with fiber 3
Is fixed with a clip 4 and a light tensile force is applied thereto so that the fiber 3 is stretched up and down.

With the fiber 3 fixed in this way, epoxy was injected into the mold 1 and cured to produce a dumbbell-shaped test piece 5. Further, the upper end of the fiber 3 which had escaped to the upper part of the mold was connected to the connector 6.

Embodiment 2 FIG. 4 shows a second embodiment of the present invention.
Shown in In the present embodiment, a weight 7 made of the same material as the epoxy to be cast at the fiber tip is provided instead of the rubber stopper 2 in the first embodiment. In other respects, it is almost the same as the above-described embodiment. The upper part of the fiber 3 was fixed with the clip 4 and the fiber 3 with the weight 7 was hung down.

However, with the pendulum motion of the fiber 3 settled down, the epoxy was cast and cured from above. In addition, the upper part of the fiber 3 is fastened with a clip 4 and a light tensile force is applied to fix the fiber 3 in a state where the fiber 3 is stretched vertically. Also,
With the fiber 3 fixed in this way, epoxy was injected into the mold and cured. The upper end of the fiber 3 that had escaped to the upper part of the mold was connected to the connector 6.

[Embodiment 3] FIG. 5 shows a third embodiment of the present invention.
Shown in In the present embodiment, a disk 8 made of the same material as the epoxy cast at the fiber tip is used instead of the rubber stopper 2 in the first embodiment.

As shown in FIG. 6, the disk 8 is
Using the same epoxy resin as the one to be injected into the mold 1, separately from the test piece, make a disk of the same diameter as the mold 1 in advance,
A hole 8a is made in the center of the hole, and the fiber 3 is fixed.

The other points are the same as those of the above-described embodiment. A disk 8 is arranged below the mold, epoxy resin is injected from above, and the optical fiber 3 at the center is entirely molded with the same epoxy resin. And a test piece 5 arranged at the center was prepared.

The upper portion of the fiber 3 is fixed with a clip 4 and a light tensile force is applied to fix the fiber 3 in a state where the fiber 3 is stretched up and down. With the fiber 3 fixed in this manner, epoxy was injected into a mold and cured. The upper end of the fiber 3 that has escaped to the upper part of the mold is the connector 6
Connected to.

[Embodiment 4] FIG. 7 shows a fourth embodiment of the present invention.
Shown in In this embodiment, a fiber fixing portion 9 is provided instead of the rubber stopper 2 in the first embodiment. The fiber fixing section 9 firstly pours a small amount of epoxy resin into the mold 1 and cures the mold. Then, the mold is once separated to take out the cured epoxy resin, and then a hole 8a is formed at the center as shown in FIG. It is opened and the fiber is fixed.

Then, the fiber fixing portion 9 is disposed again below the mold 1 and an epoxy resin is injected from above.
A test piece 5 in which the optical fiber 3 at the center was entirely molded with the same epoxy resin and the center was disposed was produced.
In addition, the upper part of the fiber 3 is fastened with a clip 4 and a light tensile force is applied to fix the fiber 3 in a state where the fiber 3 is stretched up and down.

With the fiber fixed in this way, an epoxy resin was injected into a mold and cured. The upper end of the fiber 3 that had escaped to the upper part of the mold was connected to the connector 6. In this method, the number of casting steps is increased to two, but the shape of the test piece is improved as compared with the conventional methods.

[0020]

As described above in detail with reference to the embodiments, according to the present invention, an optical fiber sensor which is an insulator which is not affected by a high electric field is reliably and easily embedded in epoxy. it can. In addition, the fiber embedding method of the present invention can be applied to any kind of object as long as it is a fiber sensor, and can perform various physical quantity measurements.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a fiber sensor according to a conventional commercial product.

FIG. 3 is a perspective view of a rubber stopper for fixing a fiber.

FIG. 4 is a sectional view of a mold according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a mold according to a third embodiment of the present invention.

FIG. 6 is a schematic view showing a fiber fixing method.

FIG. 7 is a sectional view of a mold according to a fourth embodiment of the present invention.

FIG. 8 is a schematic view showing a fiber fixing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dumbbell mold 2 Rubber stopper 3 Fiber 3a Sensor part 4 Clip 5 Dumbbell test piece 6 Connector 7 Epoxy weight 8 Disk 9 Fiber fixing part

Claims (12)

[Claims] 1. A method of embedding an optical fiber in an epoxy casting, characterized by embedding an optical fiber in an epoxy resin casting. 2. The method according to claim 1, wherein said optical fiber is an optical fiber strain sensor. 3. The method of embedding an optical fiber in an epoxy casting as claimed in claim 1, wherein said optical fiber is an optical fiber color sensor. 4. The method according to claim 1, wherein said optical fiber is an optical fiber temperature sensor. 5. The method according to claim 1, wherein the optical fiber is an optical fiber acceleration sensor. 6. The method according to claim 1, wherein the optical fiber is an optical fiber pressure sensor. 7. An injection-molded product of an optical fiber with respect to an epoxy cast product, wherein the optical fiber is embedded into an epoxy resin cast product. 8. The casting product according to claim 7, wherein said optical fiber is an optical fiber strain sensor. 9. An epoxy casting according to claim 7, wherein said optical fiber is an optical fiber color sensor. 10. The casting product according to claim 7, wherein said optical fiber is an optical fiber temperature sensor. 11. The casting product according to claim 7, wherein said optical fiber is an optical fiber acceleration sensor. 12. The casting product according to claim 7, wherein said optical fiber is an optical fiber pressure sensor.