JP2021085851A - Method for installing strain gauge - Google Patents

Abstract

To provide a gauge installation method which enables a strain gauge to be installed on a measurement object with a comparatively less man-hour and comparatively high work efficiency.SOLUTION: A strain gauge 2 is mounted on a surface of a member 1 of a structure that is a measurement object with an adhesive 3 containing an ultraviolet curable resin and a moisture curable resin. A coating agent 4 containing the ultraviolet curable resin is coated so as to cover the surface of the strain gauge 2 and the surface of the member 1 in the periphery of the strain gauge 2. A coating layer is formed by irradiating the coating agent 4 with ultraviolet rays 7 from its top to cure the coating agent 4, and the adhesive 3 is cured to form an adhesive layer.SELECTED DRAWING: Figure 1D

Description

The present invention relates to a method of installing a strain gauge on the surface of a strain measurement target.

For example, in order to grasp the stress state of a member that constitutes a structure such as a bridge, a strain gauge is installed on the member, the strain gauge is connected to an electric circuit, and a change in the resistance value of the strain gauge is detected to detect the strain of the member. I'm measuring. When a strain gauge is installed on a member, it is necessary to securely fix the strain gauge in order to accurately detect the strain of the member and to cover and protect the strain gauge in order to prevent the strain gauge from becoming dirty. Conventionally, in order to fix a strain gauge to a member, an epoxy adhesive which is a thermosetting adhesive and a cyanoacrylate adhesive which is a moisture curable adhesive are often used (see, for example, Patent Document 1). ..

4A to 4D are process diagrams showing a method of installing a conventional strain gauge using an epoxy adhesive. First, as shown in FIG. 4A, dirt, coating, and water on the surface of the member 1 to be measured are removed, and the epoxy adhesive 103 is applied to the surface of the gauge base of the strain gauge 2. Subsequently, as shown in FIG. 4B, the strain gauge 2 is arranged so that the epoxy adhesive 103 is in contact with the surface of the member 1, and a pressing force F is applied to the strain gauge 2 toward the member 1 by a clamp or the like. .. After that, as shown in FIG. 4C, heat 107 is irradiated from above the strain gauge 2 with a heater to heat and cure the epoxy adhesive 103. When the epoxy adhesive 103 is cured, the epoxy coating agent 104 is applied so as to cover the surface of the strain gauge 2 and the surface of the member 1 around the strain gauge 2, as shown in FIG. 4D. After that, as shown in FIG. 4E, heat 107 is irradiated from above the strain gauge 2 with a heater to heat and cure the epoxy coating agent 104.

In this way, the strain gauge 2 is fixed to the member 1 with the cured product of the epoxy adhesive 103, and the surface of the strain gauge 2 and the surface of the member 1 around the strain gauge 2 are covered with the cured product of the epoxy coating agent 104. By doing so, the installation of the strain gauge 2 on the member 1 is completed.

On the other hand, in the conventional strain gauge installation method using a cyanoacrylate adhesive, after removing dirt, coating and water from the surface of the member 1, the cyanoacrylate adhesive is applied to the surface of the gauge base of the strain gauge 2. To do. Subsequently, the strain gauge 2 is arranged so that the cyanoacrylate adhesive is in contact with the surface of the member 1, and acupressure is applied with the operator's finger to apply a pressing force F to the strain gauge 2 toward the member 1. When the temperature is relatively high, such as in summer, the cyanoacrylate adhesive is cured by applying finger pressure for 15 to 60 seconds, and the strain can be measured by the strain gauge 2 after about 1 hour.

Jikkai Sho 59-080435

However, in the conventional strain gauge installation method, when an epoxy adhesive is used, a step of heating and curing the epoxy adhesive 103 in order to fix the strain gauge 2 to the surface of the member 1 and strain Since a step of heating and curing the epoxy coating agent 104 is required to coat the gauge 2, there is a problem that the number of steps is large and the work efficiency is relatively low. Especially at low temperatures, the heating time of the epoxy adhesive 103 and the epoxy coating agent 104 is longer than at room temperature, so that there is a problem that the working time becomes longer and the working efficiency is further lowered.

Further, when a cyanoacrylate adhesive is used, it takes a long time to apply acupressure at a low temperature, and the cyanoacrylate adhesive may not be cured depending on the temperature and humidity.

Therefore, an object of the present invention is to provide a strain gauge installation method capable of installing a strain gauge on a measurement target with relatively high work efficiency with a relatively small number of man-hours. Another object of the present invention is to provide a method for installing a strain gauge that is not easily affected by conditions such as temperature and humidity.

In order to solve the above problems, the method of installing the strain gauge of the present invention includes a step of attaching a strain gauge having an ultraviolet-transmissive substrate to the surface of the measurement target with an ultraviolet curable adhesive.
A step of arranging an ultraviolet curable coating agent so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge.
It is characterized by comprising a step of irradiating the ultraviolet curable coating agent with ultraviolet rays to cure the ultraviolet curable adhesive and the ultraviolet curable coating agent.

According to the above configuration, a strain gauge having an ultraviolet-transmissive substrate is attached to the surface of the measurement target to be measured for strain with an ultraviolet curable adhesive. As the strain gauge, for example, a strain gauge having a pattern for measuring strain formed on the surface of the substrate can be used. Subsequently, an ultraviolet curable coating agent is placed so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge. After that, ultraviolet rays are irradiated from above the ultraviolet curable coating agent, and the ultraviolet curable coating agent covering the strain gauge is cured by the ultraviolet rays. At the same time, ultraviolet rays are transmitted through the ultraviolet curable coating agent and the substrate of the strain gauge to reach the ultraviolet curable adhesive located on the back surface of the substrate of the strain gauge, and the ultraviolet curable adhesive is cured. In this way, both the ultraviolet curable coating agent that covers the strain gauge and the ultraviolet curable adhesive that fixes the strain gauge can be cured by a single step of irradiating the strain gauge. Therefore, the strain gauge can be installed in fewer steps than fixing the strain gauge and forming the coating in different steps, and it is possible to reduce the labor and time required to install the strain gauge. Therefore, the strain gauge can be installed on the measurement target with higher work efficiency than when the strain gauge is fixed and the coating is formed in different steps. In addition, even at low temperatures, the UV curable adhesive and the UV curable coating agent cure quickly when irradiated with UV light, so compared to the case of using a thermosetting adhesive, coating agent, or cyanoacrylate adhesive. However, the work time can be shortened.

The method of installing the strain gauge according to the other aspect of the present invention includes a step of attaching a strain gauge having a substrate that transmits ultraviolet rays to the surface of the measurement target with an ultraviolet curable adhesive.
A step of arranging an ultraviolet curable coating adhesive so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge.
A step of arranging a film that transmits ultraviolet rays so as to cover the ultraviolet curable coating adhesive and the surface of the measurement target around the ultraviolet curable coating adhesive.
The film comprises a step of irradiating the film with ultraviolet rays to cure the ultraviolet curable adhesive and the ultraviolet curable coating adhesive.

According to the above configuration, a strain gauge having an ultraviolet-transmissive substrate is attached to the surface of the measurement target to be measured for strain with an ultraviolet curable adhesive. As the strain gauge, for example, a strain gauge having a pattern for measuring strain formed on the surface of the substrate can be used. Subsequently, an ultraviolet curable coating adhesive is placed so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge. Subsequently, a film that transmits ultraviolet rays is arranged so as to cover the ultraviolet curable coating adhesive and the surface of the measurement target around the ultraviolet curable coating adhesive. This film preferably substantially blocks the permeation of water in order to protect the strain gauge. After that, ultraviolet rays are irradiated from above the film, and the ultraviolet rays cover the strain gauge and cure the ultraviolet curable coating adhesive covered with the film. At the same time, ultraviolet rays are transmitted through the film, the ultraviolet curable coating adhesive, and the strain gauge substrate to reach the ultraviolet curable adhesive located on the back surface of the strain gauge substrate, and this ultraviolet curable adhesive is used. Cure. In this way, a single step of irradiating the strain gauge can cure both the UV curable coating adhesive that covers the strain gauge and is covered with a film, and the UV curable adhesive that fixes the strain gauge. it can. Therefore, the strain gauge can be installed with less man-hours than when the strain gauge is fixed, the coating is formed, and the sheet is fixed in different steps. Therefore, the strain gauge can be fixed and moisture-proof with relatively high work efficiency with less labor and time than before. In addition, even at low temperatures, the UV curable adhesive and the UV curable coating adhesive cure quickly when irradiated with UV light, so the work time is shorter than when using a thermosetting adhesive or coating agent. it can.

In the method of installing the strain gauge of one embodiment, the ultraviolet curable adhesive is a moisture curable combined type.

According to the above embodiment, since the ultraviolet curable adhesive that attaches the strain gauge to the surface of the measurement target is a moisture curing combined type, the progress of ultraviolet rays is hindered by the pattern, wire, etc. formed on the strain gauge. Even if the amount of ultraviolet rays irradiated to the ultraviolet curable adhesive is insufficient, the ultraviolet curable adhesive can be cured by moisture.

In the method of installing the strain gauge of one embodiment, the film is provided with a primer on the surface facing the strain gauge.

According to the above embodiment, the primer applied to the film enhances the adhesiveness between the film and the ultraviolet curable coating adhesive. Therefore, by curing the ultraviolet curable coating adhesive, the film is subjected to a strain gauge and a measurement target. Can be securely fixed to the surface.

In the method of installing the strain gauge of one embodiment, the film is made of fluororesin.

According to the above embodiment, the strain gauge can be stably moisture-proofed by the film formed of the fluororesin.

It is a figure which shows the process in the installation method of the strain gauge of 1st Embodiment of this invention. It is a figure which shows the process following FIG. 1A. It is a figure which shows the process following FIG. 1B. It is a figure which shows the process following FIG. 1C. It is a top view which shows the strain gauge installed by the installation method of the strain gauge of embodiment. It is sectional drawing of a strain gauge. It is a figure which shows the process in the installation method of the strain gauge of 2nd Embodiment. It is a figure which shows the process following FIG. 3A. It is a figure which shows the process following FIG. 3B. It is a figure which shows the process following FIG. 3C. It is a figure which shows the process following FIG. 3D. It is a figure which shows the process following FIG. 3E. It is a figure which shows the process in the installation method of the conventional strain gauge. It is a figure which shows the process following FIG. 4A. It is a figure which shows the process following FIG. 4B. It is a figure which shows the process following FIG. 4C. It is a figure which shows the process which follows FIG. 4D.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

1A to 1D are steps showing the installation method of the strain gauge of the first embodiment, and FIGS. 2A and 2B are a plan view and a cross-sectional view showing the strain gauge.

The strain gauge 2 is known, and includes a gauge base 21, a gauge grid 22 formed on the surface of the gauge base 21, gauge leads 26 and 26 connected to the gauge grid 22, and an end portion of the gauge grid 22. A solder portion 25 for connecting the gauge lead 26 to the gauge tab provided in the gauge base 21 and a resin cover 23 provided on the surface of the gauge base 21 to cover the gauge grid 22 are provided. The gauge base 21 is made of a polyimide resin or a polyester resin. The gauge grid 22 is formed by patterning a metal foil such as a nickel-chromium alloy or a copper-nickel alloy. The solder portion 25 is formed of, for example, a tin lead alloy or a tin silver alloy. The resin cover 23 is preferably made of a polyimide resin or a polyester resin, and is preferably made of the same material as the gauge base 21. The gauge base 21 and the resin cover 23 are made of a resin that transmits ultraviolet rays. As the gauge lead 26, a copper wire having a coating film of a vinyl resin or a fluororesin can be used.

The strain gauge 2 is installed on the member 1 of the structure to be measured, and the gauge lead 26 is connected to the measuring device via a cable. The measuring device constitutes a Wheatstone bridge circuit including the strain gauge 2, and measures the strain to be measured based on the change in the output power from the Wheatstone bridge circuit.

In the method of installing the strain gauge of the present embodiment, first, the surface of the member 1 to be measured, the position where the strain gauge 2 is to be installed, and the surrounding area are purified. To purify the surface of the member 1, first, the surface of the member 1 is polished with a sandpaper, a grinder, or the like to remove dirt, paint, rust, and the like. After that, the polishing position is wiped with absorbent cotton or the like containing a solvent such as acetone to remove particles, oils and fats and the like.

After that, as shown in FIG. 1A, the UV-moisture-combined curable adhesive 3 is applied to the surface of the gauge base 21 of the strain gauge 2 on the side in contact with the installation position of the member 1. The ultraviolet-moisture-curable adhesive 3 is formed by containing an ultraviolet-curable resin and a moisture-curable resin. As the ultraviolet curable resin, one using a photoradical polymerization type resin can be used. As the photoradical polymerization type resin, urethane acrylate-based, epoxy acrylate-based, acrylic acrylate-based, and polyester acrylate-based resins can be used. Further, as the moisture-curable resin, urethane-based, epoxy-based, acrylic-based, silicon-based or other resins can be used. In particular, as the UV-moisture-combined curable adhesive 3, a mixture of a photoradical polymerization-type UV-curable resin and an instant adhesive can be used, and a specific example thereof is TB3177 manufactured by ThreeBond Co., Ltd. Further, as the UV-moisture-combined curing type adhesive 3, an instant adhesive having a photopolymerization function can be used, and for example, an adhesive containing a cyanoacrylate-based adhesive and a photoanionic polymerization initiator can be used. it can. A specific example thereof is TB1771E manufactured by ThreeBond Co., Ltd. The adhesive 3 does not have a moisture-curing property and may be an ultraviolet-curable adhesive.

Subsequently, as shown in FIG. 1B, the strain gauge 2 is attached so that the adhesive 3 is in close contact with the surface of the member 1, and the force is applied to the surface of the strain gauge 2 with the operator's finger or the like as shown by the arrow F. And press. The strain gauge 2 may be pressed by using a jig or the like.

After that, as shown in FIG. 1C, a coating agent 4 formed containing an ultraviolet curable resin is applied so as to cover the surface of the strain gauge 2 and the surface of the member 1 around the strain gauge 2. .. As the ultraviolet curable resin contained in the coating agent 4, a photoradical polymerization type resin or a photocationic polymerization type resin can be used. As the photoradical polymerization type resin, urethane acrylate-based, epoxy acrylate-based, acrylic acrylate-based, and polyester acrylate-based resins can be used. Further, as the photocationic polymerization type resin, an epoxy-based resin, an oxetane-based resin, or a vinyl ether-based resin can be used. As a specific example of the ultraviolet curable resin, TB3013Q or TB3036 manufactured by ThreeBond Co., Ltd. can be used.

Subsequently, as shown in FIG. 1D, ultraviolet rays 7 are irradiated from above the coating agent 4. The ultraviolet light 7 can be irradiated by using, for example, a portable ultraviolet lamp having a built-in ultraviolet light emitting diode. The irradiated ultraviolet rays cause the ultraviolet curable resin of the coating agent 4 to proceed with the photopolymerization reaction to be cured, and a coating layer made of the cured product of the ultraviolet curable resin is formed. Further, the irradiated ultraviolet rays pass through the coating agent 4, the resin cover 23 of the strain gauge 2, and the gauge base 21, and reach the adhesive 3 located between the strain gauge 2 and the member 1. Due to the ultraviolet rays that have reached the adhesive 3, the photopolymerization reaction proceeds and the adhesive 3 is cured, an adhesive layer is formed by the cured product of the ultraviolet curable resin, and the strain gauge 2 is fixed to the surface of the member 1.

Here, a part of the ultraviolet rays that have reached the strain gauge 2 is hindered by the gauge grid 22 and the gauge lead 26 from advancing to the gauge base 21, and a region where the adhesive 3 is insufficiently irradiated with the ultraviolet rays is generated. However, since the adhesive 3 contains a moisture-curable resin, the curing proceeds due to the humidity, so that the curing is promoted even if a region where the irradiation with ultraviolet rays is insufficient occurs. Therefore, the strain gauge 2 can be stably fixed to the surface of the member 1.

As described above, according to the method of installing the strain gauge of the first embodiment, the adhesive 3 arranged between the surface of the member 1 and the strain gauge 2, the surface of the strain gauge 2 and the members around the strain gauge 2 The coating agent 4 that covers the surface of 1 is cured by a single irradiation with ultraviolet rays. Therefore, the strain gauge 2 can be fixed to the surface of the member 1 with a small number of steps, and the coating layer of the strain gauge 2 can be formed.

Further, according to the strain gauge installation method of the first embodiment, since the adhesive 3 containing the ultraviolet curable resin and the coating agent 4 containing the ultraviolet curable resin are used, the thermosetting adhesive is used at low temperatures. It is possible to form an adhesive layer or a coating layer more quickly than when a coating agent is used.

3A to 3F are process diagrams for explaining the method of installing the strain gauge of the second embodiment. In the method of installing the strain gauge of the second embodiment, the strain gauge 2 is coated with the film 11 in order to realize higher moisture resistance than that of the first embodiment. The strain gauge 2 installed in the second embodiment is the same as that in the first embodiment.

In the method of installing the strain gauge of the second embodiment, first, as in the first embodiment, the surface of the member 1 to be measured is cleaned at the position where the strain gauge 2 is to be installed and its surroundings. The surface of the member 1 is purified by polishing with sandpaper or the like and wiping with absorbent cotton or the like containing a solvent such as acetone.

After that, as shown in FIG. 3A, on the surface of the gauge base 21 of the strain gauge 2 on the side in contact with the installation position of the member 1, the same ultraviolet-moisture-combined curing adhesive as in the first embodiment. 3 is applied. The adhesive 3 may be an ultraviolet curable type instead of a curable type combined with ultraviolet moisture.

Subsequently, as shown in FIG. 3B, the strain gauge 2 is attached so that the adhesive 3 adheres to the surface of the member 1, and the force is applied to the surface of the strain gauge 2 with the operator's finger or the like as shown by the arrow F. And press. The strain gauge 2 may be pressed by using a jig or the like.

After that, as shown in FIG. 3C, a coating adhesive 10 formed containing an ultraviolet curable resin is applied so as to cover the surface of the strain gauge 2 and the surface of the member 1 around the strain gauge 2. To do. The coating adhesive 10 has a function of coating the strain gauge 2 and a function of adhering a film 11 described later to the surface. As the ultraviolet curable resin contained in the coating adhesive 10, the same ultraviolet curable resin as the ultraviolet curable resin contained in the coating agent 4 of the first embodiment can be used. As the ultraviolet curable resin of the coating adhesive 10, for example, TB3013Q or TB3036 manufactured by ThreeBond Co., Ltd. can be used.

Subsequently, as shown in FIG. 3D, a film 11 for covering the strain gauge 2 is prepared. The film 11 is formed of an ultraviolet-transmissive resin, and is preferably formed of, for example, a fluororesin such as PCTFE or ETFE. A primer 12 is applied to the surface of the film 11 on the side of the coating adhesive 10. As the primer 12, a primer 12 that enhances the adhesiveness between the coating adhesive 10 and the film 11 is used. As the primer 12, for example, TB7797 manufactured by ThreeBond Co., Ltd. can be used.

Subsequently, as shown in FIG. 3E, the film 11 is arranged so as to cover the surfaces of the coating adhesive 10 and the member 1 around the coating adhesive 10 so that the primer 12 comes into contact with the coating adhesive 10. ..

Subsequently, as shown in FIG. 3F, ultraviolet rays 7 are irradiated from above the film 11. The irradiated ultraviolet rays pass through the film 11 and reach the coating adhesive 10, and further pass through the coating adhesive 10 and the resin cover 23 and the gauge base 21 of the strain gauge 2 to reach the adhesive 3. The ultraviolet rays that reach each layer in this way cause the ultraviolet curable resin of the coating adhesive 10 to proceed with the photopolymerization reaction and cure, forming an adhesive layer that also serves as a coating layer of the cured product of the ultraviolet curable resin. , The strain gauge 2 is covered and the film 11 is adhered. Further, the adhesive 3 undergoes a photopolymerization reaction due to ultraviolet rays and is cured to form an adhesive layer made of a cured product of the ultraviolet curable resin, and the strain gauge 2 is fixed to the surface of the member 1.

Here, a part of the ultraviolet rays that have reached the strain gauge 2 is hindered by the gauge grid 22 and the gauge lead 26, and there is a region where the irradiation to the adhesive 3 is insufficient, but the adhesive 3 is moisture-cured. Since it contains a mold resin, it is cured by moisture. Therefore, the strain gauge 2 can be stably fixed to the surface of the member 1.

As described above, according to the method of installing the strain gauge of the second embodiment, the adhesive 3 arranged between the surface of the member 1 and the strain gauge 2, the surface of the strain gauge 2 and the members around the strain gauge 2 The coating adhesive 10 covering the surface of 1 is cured by a single irradiation with ultraviolet rays. Therefore, the strain gauge 2 can be fixed to the surface of the member 1 with a small number of steps, the coating layer of the strain gauge 2 can be formed, and the film 11 can be coated and fixed on the strain gauge 2. ..

Further, according to the strain gauge installation method of the second embodiment, since the adhesive 3 containing the ultraviolet curable resin and the coating adhesive 10 containing the ultraviolet curable resin are used, the thermosetting adhesive is adhered at a low temperature. An adhesive layer or a coating adhesive layer can be formed more quickly than when an agent or a coating adhesive is used.

Further, the coating agent 4 used in the strain gauge installation method of the first embodiment and the coating adhesive 10 used in the strain gauge installation method of the second embodiment had the same composition, but the first embodiment. In the method of installing the strain gauge, the coating agent 4 does not have to have the effect of adhering a film or the like to the surface side as long as it covers the strain gauge 2 and exerts an antifouling effect.

The present invention is not limited to the embodiments described above, and many modifications can be made by those who have ordinary knowledge in the art within the technical idea of the present invention.

1 member 2 strain gauge 3 adhesive 4 coating agent 7 ultraviolet rays 10 coating adhesive 11 film 12 primer

Claims (5)

A process of attaching a strain gauge having an ultraviolet-transmissive substrate to the surface of the measurement target with an ultraviolet-curable adhesive, and
A step of arranging an ultraviolet curable coating agent so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge.
A method for installing a strain gauge, which comprises a step of irradiating ultraviolet rays from above the ultraviolet curable coating agent to cure the ultraviolet curable adhesive and the ultraviolet curable coating agent. A process of attaching a strain gauge having a substrate that transmits ultraviolet rays to the surface of the measurement target with an ultraviolet curable adhesive, and
A step of arranging an ultraviolet curable coating adhesive so as to cover the surface of the strain gauge and the surface of the measurement target around the strain gauge.
A step of arranging a film that transmits ultraviolet rays so as to cover the ultraviolet curable coating adhesive and the surface of the measurement target around the ultraviolet curable coating adhesive.
A method for installing a strain gauge, which comprises a step of irradiating the film with ultraviolet rays to cure the ultraviolet curable adhesive and the ultraviolet curable coating adhesive. In the method for installing a strain gauge according to claim 1 or 2,
A method for installing a strain gauge, wherein the ultraviolet curable adhesive is a moisture curable combined type. In the method for installing a strain gauge according to claim 2,
The film is a method of installing a strain gauge, characterized in that a primer is applied to the surface facing the strain gauge. In the method for installing a strain gauge according to claim 2,
A method for installing a strain gauge, wherein the film is made of fluororesin.

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