JP7411395B2 - How to install strain gauges - Google Patents

Description

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

For example, in order to understand the stress state of members that make up structures such as bridges, strain gauges are installed on the members, the strain gauges are connected to an electric circuit, and changes in the resistance value of the strain gauges are detected to determine the strain in the members. Measuring. When installing a strain gauge on a member, it is necessary to securely fix the strain gauge in order to accurately detect the strain in the member, and to protect the strain gauge by covering it to prevent it from being soiled. Conventionally, in order to fix strain gauges to members, epoxy adhesives that are thermosetting adhesives and cyanoacrylate adhesives that are moisture-curable adhesives are often used (for example, see Patent Document 1). .

4A to 4D are process diagrams showing a conventional method of installing a strain gauge using an epoxy adhesive. First, as shown in FIG. 4A, dirt, paint, and water are removed from the surface of the member 1 to be measured, and an 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 placed 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 using a clamp or the like. . Thereafter, as shown in FIG. 4C, heat 107 is applied from above the strain gauge 2 using a heater to heat and harden the epoxy adhesive 103. When the epoxy adhesive 103 hardens, an epoxy coating agent 104 is applied 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. Thereafter, as shown in FIG. 4E, heat 107 is applied from above the strain gauge 2 using a heater to heat and harden 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 coated 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 cyanoacrylate adhesive, after removing dirt, paint, and water from the surface of member 1, cyanoacrylate adhesive is applied to the surface of the gauge base of strain gauge 2. do. Subsequently, the strain gauge 2 is placed so that the cyanoacrylate adhesive 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 finger pressure of the operator. 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 strain can be measured using the strain gauge 2 after about an hour.

Publication No. 59-080435

However, when using an epoxy adhesive, the conventional strain gauge installation method described above requires 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 a step of curing the epoxy adhesive 103. Since it is necessary to heat and harden the epoxy coating agent 104 in order to cover the gauge 2, there is a problem that the number of steps is large and the work efficiency is relatively low. Particularly at low temperatures, the heating time for the epoxy adhesive 103 and the epoxy coating agent 104 is longer than at room temperature, which increases the working time and further reduces working efficiency.

Furthermore, when a cyanoacrylate adhesive is used, the time required to apply finger pressure is longer at low temperatures, and the cyanoacrylate adhesive may not harden depending on the temperature and humidity.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a strain gauge installation method that allows a strain gauge to be installed on a measurement target with relatively low man-hours and relatively high work efficiency. Another object of the present invention is to provide a method for installing strain gauges that is not easily affected by conditions such as temperature and humidity.

In order to solve the above problems, the strain gauge installation method of the present invention includes the steps of attaching a strain gauge having an ultraviolet-transparent base to the surface of a measurement target using an ultraviolet-curable adhesive;
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;
The method is characterized by comprising a step of curing the ultraviolet curable adhesive and the ultraviolet curable coating by irradiating ultraviolet rays from above the ultraviolet curable coating agent.

According to the above configuration, a strain gauge having an ultraviolet-transparent base is attached to the surface of the measurement target whose strain is to be measured using an ultraviolet-curable adhesive. As the strain gauge, for example, one in which a pattern for measuring strain is formed on the surface of a base 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 object to be measured around the strain gauge. After that, ultraviolet rays are irradiated from above the ultraviolet curable coating agent, and the ultraviolet ray curable coating agent covering the strain gauge is cured by the ultraviolet rays. At the same time, the ultraviolet rays are transmitted through the ultraviolet curable coating agent and the base of the strain gauge, and reach the ultraviolet curable adhesive located on the back surface of the strain gauge base, thereby curing the ultraviolet curable adhesive. In this way, by a single step of irradiating ultraviolet rays, both the ultraviolet curable coating agent covering the strain gauge and the ultraviolet curable adhesive fixing the strain gauge can be cured. Therefore, rather than fixing the strain gauge and forming the coating in different processes, the strain gauge can be installed in fewer steps, and the effort and time required to install the strain gauge can be reduced. Therefore, the strain gauge can be installed on the measurement target with higher work efficiency than when fixing the strain gauge and forming the coating are performed in different processes. In addition, even at low temperatures, UV-curable adhesives and UV-curable coatings cure quickly when exposed to UV rays, so they are more effective than thermosetting adhesives, coatings, and cyanoacrylate adhesives. It can also shorten working time.

A method for installing a strain gauge according to another aspect of the present invention includes the steps of attaching a strain gauge having a base that transmits ultraviolet rays to the surface of a measurement target using an ultraviolet curable adhesive;
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;
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 method includes a step of curing the ultraviolet curable adhesive and the ultraviolet curable coating adhesive by irradiating ultraviolet rays from above the film.

According to the above configuration, a strain gauge having an ultraviolet-transparent base is attached to the surface of the measurement target whose strain is to be measured using an ultraviolet-curable adhesive. As the strain gauge, for example, one in which a pattern for measuring strain is formed on the surface of a base 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 object to be measured around the strain gauge. Subsequently, a film that transmits ultraviolet rays is placed so as to cover the ultraviolet curable coating adhesive and the surface of the object to be measured around the ultraviolet curable coating adhesive. Preferably, the film substantially blocks water transmission to protect the strain gauge. Thereafter, ultraviolet rays are irradiated from above the film, and the ultraviolet curable coating adhesive that covers the strain gauge and is covered with the film is cured by the ultraviolet rays. At the same time, the ultraviolet rays are transmitted through the film, the ultraviolet curable coating adhesive, and the strain gauge base, and reach the ultraviolet curable adhesive located on the back side of the strain gauge base. Let it harden. In this way, a single step of irradiating UV light 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. can. Therefore, the strain gauge can be installed with fewer man-hours than when fixing the strain gauge, forming a coating, and fixing the sheet are performed in different steps. Therefore, the strain gauge can be fixed and moisture-proofed with less effort and time than in the past, and with relatively high work efficiency. In addition, even at low temperatures, UV-curable adhesives and UV-curable coating adhesives cure quickly when exposed to UV rays, reducing work time compared to using thermosetting adhesives and coatings. can.

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

According to the above embodiment, since the UV-curable adhesive that attaches the strain gauge to the surface of the measurement target is a moisture-curable adhesive, the progress of the UV rays is hindered by the patterns, wires, etc. formed on the strain gauge. Even if the amount of ultraviolet rays irradiated to the ultraviolet curable adhesive becomes insufficient, the ultraviolet curable adhesive can be cured by moisture.

In one embodiment of the strain gauge installation method, 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 increases the adhesion between the film and the UV-curable coating adhesive, so that the film can be used as the strain gauge and the measurement target by curing the UV-curable coating adhesive. Can be securely fixed to surfaces.

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

According to the above embodiment, the strain gauge can be stably moisture-proofed by the film formed of 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. FIG. 2 is a plan view showing a strain gauge installed by the strain gauge installation method of the embodiment. FIG. 3 is a cross-sectional view 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. FIG. 3 is a diagram showing steps in a conventional strain gauge installation method. 4A is a diagram showing a step subsequent to FIG. 4A. FIG. It is a figure which shows the process following FIG. 4B. FIG. 4C is a diagram showing a step following FIG. 4C. It is a figure which shows the process following FIG. 4D.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to illustrated embodiments.

1A to 1D are steps showing a method for installing a strain gauge according to the first embodiment, and FIGS. 2A and 2B are a plan view and a sectional view showing the strain gauge.

The strain gauge 2 is a known strain gauge, and includes a gauge base 21, a gauge grid 22 formed on the surface of the gauge base 21, gauge leads 26, 26 connected to the gauge grid 22, and an end of the gauge grid 22. A solder portion 25 connects a gauge lead 26 to a gauge tab provided on the gauge base 21 , and a resin cover 23 is provided on the surface of the gauge base 21 and covers the gauge grid 22 . The gauge base 21 is made of polyimide resin or 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 made of, for example, a tin-lead alloy or a tin-silver alloy. The resin cover 23 is preferably made of polyimide resin or 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 resin that transmits ultraviolet rays. The gauge lead 26 may be a copper wire coated with vinyl resin or fluororesin.

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

In the strain gauge installation method of this embodiment, first, 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. To clean the surface of the member 1, first, the surface of the member 1 is polished with sandpaper, a grinder, etc. to remove dirt, paint, rust, etc. Thereafter, the polishing position is wiped with absorbent cotton or the like containing a solvent such as acetone to remove particles, oil, etc.

Thereafter, as shown in FIG. 1A, an ultraviolet and moisture-curable adhesive 3 is applied to the surface of the gauge base 21 of the strain gauge 2 that is in contact with the installation position of the member 1. The ultraviolet and moisture curable adhesive 3 is formed to include an ultraviolet curable resin and a moisture curable resin. As the ultraviolet curable resin, one using a photoradical polymerizable resin can be used. As the photo-radical polymerizable resin, urethane acrylate-based, epoxy acrylate-based, acrylic acrylate-based, and polyester acrylate-based resins can be used. Furthermore, as the moisture-curable resin, urethane-based, epoxy-based, acrylic-based, silicone-based, and other resins can be used. In particular, the UV-moisture-curable adhesive 3 can be a mixture of a photo-radical polymerizable UV-curable resin and an instant adhesive, and a specific example thereof is TB3177 manufactured by ThreeBond. In addition, the adhesive 3 that can be cured with ultraviolet moisture and moisture can be an instant adhesive with a photopolymerization function; for example, an adhesive containing a cyanoacrylate adhesive and a photoanionic polymerization initiator can be used. can. A specific example thereof is TB1771E manufactured by ThreeBond. Note that the adhesive 3 may be an ultraviolet curing adhesive without moisture curing properties.

Next, 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 a force is applied to the surface of the strain gauge 2 with an operator's finger as shown by arrow F. Add and press. Note that the strain gauge 2 may be pressed using a jig or the like.

After that, as shown in FIG. 1C, a coating agent 4 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. . The ultraviolet curable resin contained in the coating agent 4 may be a photo-radical polymerizable resin or a cationic photo-polymerizable resin. As the photo-radical polymerizable resin, urethane acrylate-based, epoxy acrylate-based, acrylic acrylate-based, and polyester acrylate-based resins can be used. Furthermore, as the photo-cationic polymerizable resin, epoxy-based, oxetane-based, and vinyl ether-based resins can be used. As a specific example of the ultraviolet curable resin, TB3013Q or TB3036 manufactured by ThreeBond can be used.

Subsequently, the coating agent 4 is irradiated with ultraviolet rays 7 from above, as shown in FIG. 1D. The ultraviolet light 7 can be irradiated using, for example, a portable ultraviolet lamp with a built-in ultraviolet light emitting diode. Due to the irradiated ultraviolet rays, the ultraviolet curable resin of the coating agent 4 undergoes a photopolymerization reaction and is cured, thereby forming a coating layer of a cured product of the ultraviolet curable resin. Further, the irradiated ultraviolet light passes through the coating agent 4, the resin cover 23 of the strain gauge 2, and the gauge base 21, and reaches the adhesive 3 located between the strain gauge 2 and the member 1. Due to the ultraviolet rays that have arrived, the adhesive 3 undergoes a photopolymerization reaction and is cured, and an adhesive layer of the cured ultraviolet curable resin is formed, thereby fixing the strain gauge 2 to the surface of the member 1.

Here, a portion of the ultraviolet rays that have reached the strain gauge 2 are prevented from advancing toward the gauge base 21 by the gauge grid 22 and the gauge leads 26, creating a region where the adhesive 3 is insufficiently irradiated with ultraviolet rays. However, since the adhesive 3 contains a moisture-curable resin, the curing progresses due to moisture, so even if some areas are insufficiently irradiated with ultraviolet rays, curing is accelerated. Therefore, the strain gauge 2 can be stably fixed to the surface of the member 1.

As described above, according to the strain gauge installation method of the first embodiment, the adhesive 3 placed between the surface of the member 1 and the strain gauge 2, and the surface of the strain gauge 2 and the members around the strain gauge 2 The coating agent 4 covering the surface of the substrate 1 is cured by one-time 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 an ultraviolet curable resin and the coating agent 4 containing an ultraviolet curable resin are used, the thermosetting adhesive 3 is used at low temperatures. Adhesive layers and coating layers can be formed more quickly than when using adhesives or coating agents.

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

In the method for installing a strain gauge according to 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 cleaned 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, an ultraviolet moisture-curable adhesive similar to the first embodiment is applied to the surface of the gauge base 21 of the strain gauge 2 that is in contact with the installation position of the member 1. Apply 3. Note that the adhesive 3 may be an ultraviolet curing type instead of an ultraviolet moisture curing type.

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

After that, as shown in FIG. 3C, a coating adhesive 10 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. do. This coating adhesive 10 has a function of coating the strain gauge 2 and a function of adhering a film 11, which will be described later, to the surface. The ultraviolet curable resin contained in this coating adhesive 10 can be the same as the ultraviolet curable resin contained in the coating agent 4 of the first embodiment. As the ultraviolet curing resin of the coating adhesive 10, for example, TB3013Q or TB3036 manufactured by ThreeBond can be used.

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

Subsequently, as shown in FIG. 3E, the film 11 is placed so as to cover the coating adhesive 10 and the surface of the member 1 around the coating adhesive 10 so that the primer 12 contacts the coating adhesive 10. .

Subsequently, as shown in FIG. 3F, the film 11 is irradiated with ultraviolet rays 7 from above. The irradiated ultraviolet light passes through the film 11 and reaches the coating adhesive 10, and further passes through the coating adhesive 10, the resin cover 23 of the strain gauge 2, and the gauge base 21, and reaches the adhesive 3. Due to the ultraviolet rays that have reached each layer in this way, the ultraviolet curable resin of the coating adhesive 10 undergoes a photopolymerization reaction and is cured, 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 bonded. Further, the adhesive 3 undergoes a photopolymerization reaction and is cured by ultraviolet rays, and an adhesive layer of a cured ultraviolet curable resin is formed, thereby fixing the strain gauge 2 to the surface of the member 1.

Here, some of the ultraviolet rays that reach the strain gauge 2 are blocked by the gauge grid 22 and the gauge leads 26, resulting in areas where the adhesive 3 is insufficiently irradiated, but the adhesive 3 is cured by moisture. Since it contains mold resin, curing is accelerated by moisture. Therefore, the strain gauge 2 can be stably fixed to the surface of the member 1.

As described above, according to the strain gauge installation method of the second embodiment, the adhesive 3 placed 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 one-time irradiation with ultraviolet rays. Therefore, the strain gauge 2 can be fixed to the surface of the member 1 with a few 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 an ultraviolet curable resin and the coating adhesive 10 containing an ultraviolet curable resin are used, the thermosetting adhesive can be used at low temperatures. Adhesive layers and coating adhesive layers can be formed more quickly than when using adhesives or coating adhesives.

Moreover, 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 In the strain gauge installation method described above, the coating agent 4 does not need to have the effect of adhering a film or the like to the surface side, as long as it coats the strain gauge 2 and has an effect of preventing staining.

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

1 Component 2 Strain gauge 3 Adhesive 4 Coating agent 7 Ultraviolet rays 10 Coating adhesive 11 Film 12 Primer

Claims (5)

a step of attaching a strain gauge having an ultraviolet-transparent base to the surface of the measurement target using an ultraviolet-curing adhesive;
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;
Installation of a strain gauge characterized by comprising the step of irradiating ultraviolet rays from above the ultraviolet curable coating agent and curing the ultraviolet ray curable adhesive and the ultraviolet curable coating agent by one irradiation of ultraviolet rays. Method. a step of attaching a strain gauge having a base that transmits ultraviolet rays to the surface of the measurement target using an ultraviolet curable adhesive;
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;
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, comprising the step of curing the ultraviolet curable adhesive and the ultraviolet curable coating adhesive by irradiating ultraviolet rays from above the film. The method for installing a strain gauge according to claim 1 or 2,
A method for installing a strain gauge, characterized in that the ultraviolet curable adhesive is of a moisture curing type. In the strain gauge installation method according to claim 2,
A method for installing a strain gauge, characterized in that the film has a primer applied to the side facing the strain gauge. In the strain gauge installation method according to claim 2,
A method for installing a strain gauge, characterized in that the film is made of fluororesin.

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