JPH06341965A - Inspection method for deterioration of painted film and its inspection device - Google Patents

Abstract

PURPOSE:To remotely measure the deterioration of a painted film without influence of weather or time by remotely thermally exciting a painted film to be inspected, and measuring its temperature distribution in noncontact state. CONSTITUTION:A deteriorated painted film B is inferior in thermal conductivity to a sound painted film A on account of air lying between the painted film and the surface of a part. Thus, immediately after turning on a heating infrared lamp 3000, the temperature rise of the film B is quicker than that of the film A, and after heating for a long time, the films A, B become the same in their temperatures. When the lamp 3000 is turned off in this state, the temperature of the film A lowers quicker than that of the film B. Temperature difference between the films A, B can therefore be caused by heating the surface of the film 2000 for a short time, and temperature distribution on the surface of the film 2000 can be measured in noncontact state by an InSD infrared detector and the like having detecting wave length in 3 to 6mum band. Heat excitation and measurement of the temperature difference distribution are interlocked in this way, and temperature distribution image is freeze-recorded under a condition where the temperature difference is the maximum, and the lamp 3000 is automatically turned off. The position and area of the deteriorated painted film within a picture plane can be on-linely computed by taking a freeze-image as an object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film deterioration inspection method and inspection device for diagnosing coating deterioration of outdoor structures such as bridges, tanks, antenna towers and buildings.

[0002]

2. Description of the Related Art Paint films exposed outdoors are exposed to ultraviolet rays, heat,
It deteriorates due to rainwater, etc., and if left unattended, the base material will rust. To maintain the aesthetics and asset value of outdoor structures,
It is important to diagnose the deterioration of the coating film, and it is necessary to repaint it before rusting. Judgment of the repainting timing and the repainting range is important in order to make maintenance costs economical.

As a method for diagnosing the deterioration of a coating film, various methods have been proposed and put into practical use. For example, in addition to a visual inspection using a deterioration degree sample together, there is a method of electrochemically measuring the thickness of the coating film, or an objective inspection method such as a cross-cut test for examining the adhesion of the coating film. However, these inspection methods require inspection near the object to be inspected or, in the case of the above-mentioned objective inspection method, in contact with the object to be inspected. Could not be remotely diagnosed.

On the other hand, the method for diagnosing peeling of an outer wall tile of a building by an infrared image device according to the present invention is a method for diagnosing remotely, and its principle is a peeling part of a tile heated by radiant heat of the sun. And the peeling portion is detected by measuring the temperature difference of the tile surface in the sound portion. That is, the heat of the tile surface is smoothly transferred to the concrete in the sound part, but the peeling part has an air layer, which is a poor heat conductor, at the interface, so it is difficult for the heat to escape, and The phenomenon that the tile surface temperature rises is used.

[0005]

Since the conventional infrared diagnostic method is a passive inspection method using the sun as a heat source, it has a drawback that it is affected by weather, time and place. Further, according to the study by the present inventors, in the case of the method using the sun as a heat source, it is found that the temperature difference between the coating film surface and the substrate hardly occurs in the natural state because the coating film is thin. . for that reason,
The conventional infrared diagnostic method cannot be applied to the deterioration diagnosis of the coating film.

Further, the conventional infrared diagnostic method has only been required to diagnose the presence or absence of peeling of a large object such as a tile or mortar, but in the case of the coating film targeted by the present invention, at the initial stage of deterioration of the coating film, Since blisters, peelings, and cracks to be detected occur in a narrow area of the coating film, the position resolution of the infrared imaging device is necessary for remote diagnosis.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a coating film deterioration inspecting method and an inspection device for remotely judging deterioration of a coating film regardless of weather and time. To do.

[0008]

In order to achieve the above object, a coating film deterioration inspection method of the present invention comprises a thermal excitation step of remotely thermally exciting a coating film to be inspected, and a temperature distribution of the coating film to be inspected. And a deteriorated portion determination step of determining a deteriorated portion from the temperature distribution induced by the thermal excitation step.

The thermal excitation step is performed by temporarily irradiating a focused infrared beam.

Further, the non-contact measurement step is performed by an infrared imaging device which detects infrared rays in a wavelength band of 3 μm to 6 μm or a wavelength band of 8 μm to 14 μm.

Further, in the deteriorated portion determining step, the maximum temperature and the minimum temperature in the same infrared image in the defined field of view are measured, and the temperature difference is a predetermined temperature or a time point when the temperature difference becomes maximum. It is characterized in that it is performed for the temperature distribution image of.

Further, the coating film deterioration inspection apparatus of the present invention comprises an infrared projector for projecting infrared rays onto the coating film to be inspected, an infrared telescope for capturing the coating film to be inspected, and the coating film to be inspected. It is characterized by comprising an infrared imaging device for measuring a temperature distribution and an infrared image processing device for judging a deteriorated portion from the temperature distribution of the coating film to be inspected.

The infrared projection device is incorporated into the infrared telescope and is a coaxial illumination.

Further, the infrared telescope is a reflection type telescope equipped with a low magnification telescope for capturing a coating film to be inspected.

Further, the infrared image processing device includes a measurement visual field limiting circuit for cutting out an image output from the infrared image device,
A comparison circuit that has a detection circuit that detects the maximum temperature and the minimum temperature in the measurement field of view, and that calculates the temperature difference between the maximum temperature and the minimum temperature, and that compares the temperature registered in advance with the temperature difference. It is characterized by comprising a circuit, a circuit that freezes an infrared image based on the output of the comparison circuit, and a trigger output circuit that notifies the freeze time of the circuit to the outside.

Further, the present invention is characterized in that the infrared projection device has a function of stopping the projection of light by a trigger output from the infrared image processing device.

[0017]

The coating film deterioration inspection method of the present invention is an improvement over the drawbacks of the conventional infrared diagnostic method, and is one of the features of actively thermally exciting the coating film to be inspected. The inventors of the present invention tried to diagnose the deterioration of the coating film by directing the infrared imaging device to the deteriorated coating film to be inspected, but only a uniform image was obtained,
Deterioration judgment was impossible. The reason for this is that in a thin object to be inspected, such as a coating film, having a thickness of, for example, 1 mm or less, the temperature of the coating film surface is almost the same as that of the base surface because the surface temperature of the coating film is almost the same. This is because there is no temperature difference even if the film is peeled off.

The present invention distinguishes a deteriorated coating film from a healthy coating film by heating the surface of the coating film for a short time and utilizing the transient characteristics of the temperature rise. It is possible to determine the deterioration of the coating film.

[0019]

EXAMPLES FIGS. 3 and 4 are views for schematically explaining the principle of the coating film deterioration inspection method of the present invention. FIG. 3 is a cross-sectional view of a painted model member, 1000 is a coating base, and 2000 is a coating base.
Is a coating film, and 3000 is an infrared lamp for heating the model member. A indicates a healthy coating film portion, and B indicates a deteriorated coating film portion in which swelling has occurred. In the deteriorated coating film portion B, since air is present at the interface between the coating film 2000 and the coating base 1000, the thermal conductivity in the direction of the coating base 1000 is inferior to that of the sound coating film portion A. Since the outdoor structure is usually made of steel, the coating base 1000 has better thermal conductivity than the coating film 2000.

FIG. 4 shows the time dependence of the temperature changes of the sound coating film portion A and the deteriorated coating film portion B. FIG. 4 (a) shows the infrared lamp off, and FIG. 4 (b) shows the infrared lamp on. Immediately after,
(C) is the case where the infrared lamp is turned off after heating. The temperatures of the sound paint film portion A and the deteriorated paint film portion B can be obtained in a non-contact manner by using a commercially available infrared imaging device. When the infrared lamp of FIG. 4A is off, the temperature of the sound coating film portion A and the deterioration coating film portion B are the same, and there is no time dependency. In the case immediately after the infrared lamp of FIG. 4B is turned on,
Although the temperature rise of the deteriorated coating film portion B is faster than that of the normal coating film portion A, both the normal coating film portion A and the deteriorated coating film portion B have the same temperature when heated by an infrared lamp for a long time. Then, in the case of FIG. 4C in which the infrared lamp is turned off in this state, the sound coating film portion A
The temperature is lower than that of the deteriorated coating film portion B.

In this way, by heating the surface of the coating film 2000 for a short time, the temperature difference between the normal coating film portion A and the deteriorated coating film portion B can be artificially created transiently. In order to detect the coating film in the early stage of deterioration with high sensitivity, it is desirable to measure under the condition where the temperature difference is the largest, for example, after the time indicated by the arrow in the case of FIG. 4B.

Since it is necessary to measure the temperature distribution on the surface of the coating film 2000 in a non-contact manner, an InSb infrared detector having a detection wavelength of 3 μm to 6 μm band, an infrared solid-state image pickup device, an HgCdTe infrared ray of 8 μm to 14 μm band is used. It is desirable to do so using an infrared imager with a built-in detector.

Another feature of the present invention is that the film to be inspected is automatically inspected under the optimum conditions in which the temperature difference between the sound coating film portion and the deteriorated coating film portion is maximized. That is, since the active thermal excitation and the measurement of the temperature difference distribution are performed in conjunction with each other as described above, the temperature distribution image is frozen and recorded under the condition where the temperature difference is the largest, and the infrared lamp is automatically operated. It is turned off. Then, for this freeze image, the position, area, etc. of the deteriorated coating film portion existing on the screen are calculated online or offline. Due to such characteristics, the inspector points the coating film inspection device of the present invention to the film to be inspected and simply presses the measurement start button to automatically display the inspection result.

As a method for automatically finding the above-mentioned optimum condition, for example, the following method can be adopted. That is, when the measurement start button of the coating film deterioration inspection device is pressed, the thermal excitation of the film to be inspected starts and the maximum and minimum temperatures appearing in the measurement screen of the infrared imager are measured in real time, and the time difference between the temperatures is measured. Examine the dependencies. Then, the temperature distribution image at the time when the temperature difference reaches the maximum or a predetermined temperature is frozen, and the thermal excitation is stopped. The reason for choosing the highest temperature and the lowest temperature in the same image is that the highest temperature occurs in the part of the deteriorated coating film where the heat conduction with the substrate is the worst, and the lowest temperature is found in the sound coating film part. .

Next, another feature of the present invention will be described. According to the coating film deterioration inspection method of the present invention, the infrared imaging device can inspect the coating film to be inspected at a remote place with a resolution of about several millimeters by the infrared telescope equipped as standard. Since the telescope is capable of coaxially irradiating infrared rays for thermal excitation peculiar to the present invention, the thermal excitation region and the measurement region are automatically aligned. 5 for a telescope
To inspect a coating film at a distance of 0 m, for example, a viewing angle of 2.
It is desirable to use a super telescope of 5 degrees or less.

The present invention will be described in more detail below with reference to the drawings, but the following is only an example of the present invention and does not limit the technical scope of the present invention.

FIG. 1 is a schematic explanatory view of a coating film deterioration inspection apparatus showing a first embodiment of the present invention.
00, infrared telescope 200, infrared imaging device 300,
The infrared image processing device 400 is included. The infrared projector 100 includes an infrared lamp 1, a condenser mirror 2, a power source 3,
It is composed of a switch 4 and a reflecting mirror 5. The infrared telescope 200 includes a primary mirror 10, a secondary mirror 11, a lens 12, and a support 1.
3 and the lens barrel 14. The infrared imager 300 is, for example, a commercially available infrared imager (Mitsubishi Thermal Imager, manufactured by Mitsubishi Electric, IR-M300) and the like, and other than the infrared detector 20, the infrared detector is not shown in the figure. 20
It has a built-in Stirling cycle cooler for cooling.

Next, the components of the infrared projector 100,
The functions and operations of the devices will be described. The infrared lamp 1 uses a tungsten filament as a light source, and the emitted infrared rays and visible rays are parabolic focusing mirrors 2.
Then, it is formed into a parallel beam and becomes the infrared light flux 6 and is incident on the side surface of the lens barrel 14 of the infrared telescope 200.
The incident infrared light flux 6 is projected onto the coating film to be inspected by the reflecting mirror 5 attached to the support 13 coaxially with the infrared telescope 200. The switch 4 is automatically turned off by a trigger from the infrared image processing device 400 described later.

The infrared telescope 200 has a focal length of 200
mm Cassegrain type reflecting telescope, which is a primary mirror 10,
The sub mirror 11, the lens 12, the support 13 for fixing and supporting the sub mirror 11 and the reflecting mirror 5, and the lens barrel 14 for housing these optical components. The incident light ray a entering the infrared telescope 200 is reflected by the main mirror 10 and becomes a light ray b and enters the sub mirror 11, the reflected light ray c is refracted by the silicon lens 12, and the refracted light d is the infrared detector. Enter 20.

Although not shown in FIG. 1, the infrared telescope 200 is equipped with a low-magnification telescope with a magnification of 2 for capturing a distant inspected coating film.
The low magnification telescope has a crosshair in the field of view,
Infrared imaging device 3 so that the inspection target is aligned with the crosshair
The direction of 00 should be adjusted. The reason why such a low magnification telescope is used together is that the viewing angle is 1.8 × 1.4 degrees in the case of only the telescope having the focal length of 200 mm according to the present embodiment, which means that only a very narrow visual field is greatly expanded. Therefore, it is very difficult to capture the inspection target.

Next, the function of the infrared image processing apparatus 400 will be described. FIG. 2 is a circuit block diagram of an infrared image processing apparatus 400 that is the core of the present invention, and includes a measurement visual field limiting circuit 30, a maximum temperature detection circuit 31 that detects the maximum temperature in the measurement visual field, and a minimum temperature detection circuit. Circuit 32 and temperature difference calculation circuit 33 for calculating the temperature difference between the maximum temperature and the minimum temperature
And the maximum temperature difference memory circuit 34 for registering the maximum temperature difference
And a registered temperature difference memory 35, a switch 36, a temperature difference comparison circuit 37, an infrared image freeze circuit 38, a deterioration area calculation / display circuit 39, and a trigger output circuit 40.

The measurement visual field limiting circuit 30 is a circuit for cutting out an image output from the infrared imager 300. Image cutting can be performed by using the cursor keys to cut out an arbitrary area in the vertical and horizontal directions. According to the inspection method of the present invention, for example, when inspecting a coating film on a steel tower against a blue sky, it is necessary to remove the background image in the infrared image. This is because the minimum temperature detection circuit 32, which will be described later, is for detecting the temperature of the sound coating film portion. However, when the background image is included, the minimum temperature is normally detected in the background image portion and the infrared projection is performed. This is because the minimum temperature does not change even when the optical device 100 is operated, and it becomes impossible to detect the temperature of the sound coating film portion.

The maximum temperature detection circuit 31 and the minimum temperature detection circuit 32 are provided for the video output of the measurement visual field limiting circuit 30, and the maximum temperature and the minimum temperature in one image frame are detected in almost real time.

The temperature difference calculation circuit 33 is a subtraction circuit for the maximum temperature and the minimum temperature. Then, the maximum temperature difference memory circuit 34 updates and registers only the maximum temperature in the time series of temperature differences sent from the temperature difference calculation circuit 33.

The registered temperature difference memory 35 is for registering the temperature set manually. The switch 36 switches between the maximum temperature difference and the registered temperature difference.

Now, the temperature difference calculation circuit 33 and the switch 3
The temperature difference comparison circuit 37 compares the measured temperature difference with the registered temperature difference. When the switch 36 is connected to the registered temperature difference memory 35, the temperature difference comparison circuit 37 compares the measured temperature difference with the registered temperature difference, and if they are the same, the image freeze circuit 38 fixes the image, The deterioration area calculation / display circuit 39 displays the inspection result. In this case, the trigger output circuit 40 activates the switch 4 of the infrared light projecting device 100 to stop the infrared light projecting.

The switch 36 is the maximum temperature difference memory circuit 3
4 is connected, the measured temperature difference and the maximum registered temperature difference are compared, and if the measured temperature becomes low, the image is fixed by the image freeze circuit 38 and inspected by the deterioration area calculation / display circuit 39. The result is displayed. Also in this case, similarly, the trigger output circuit 40 operates the switch 4 of the infrared light projecting device 100 to stop the infrared light projecting.

[0038]

As described above, according to the coating film deterioration inspection method and the inspection device of the present invention, since the means for thermally exciting the coating film to be inspected is provided, regardless of the weather, date and time, place. The coating film deterioration inspection can be performed. Also,
Since it is equipped with an infrared telescope, it is possible to remotely inspect swelling, peeling, etc. of the fine coating film.

Since the present invention has such characteristics, it is possible to prevent coating deterioration of outdoor structures such as bridges, tanks, and antenna towers and buildings, which has been impossible in the past, regardless of weather, date, and place. It is possible to diagnose remotely.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view of a coating film deterioration inspection apparatus showing an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing an example of the infrared image processing apparatus of FIG.

FIG. 3 is a cross-sectional view of a coating section for explaining the principle of the coating film deterioration inspection method of the present invention.

FIG. 4 is a characteristic diagram illustrating the principle of the coating film deterioration inspection method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Infrared lamp, 2 ... Condensing mirror, 3 ... Power supply, 4 ... Switch, 5 ... Reflecting mirror, 6 ... Infrared light flux, 10 ... Primary mirror, 11 ... Secondary mirror, 12 ... Lens, 13 ... Support, 14 ... Lens barrel, 20 ...
Infrared detector, 100 ... Infrared projector, 200 ... Infrared telescope, 300 ... Infrared imaging device, 400 ... Infrared image processing device, 1000 ... Coating base, 2000 ... Coating film,
3000 ... Infrared lamp.

Claims (9)

[Claims] 1. A thermal excitation step of remotely thermally exciting a coating film to be inspected, a non-contact measuring step of measuring a temperature distribution of the coating film to be inspected in a non-contact manner, and a temperature distribution induced by the thermal excitation step. And a deterioration portion determining step of determining a deterioration portion. 2. The coating film deterioration inspection method according to claim 1, wherein the thermal excitation step is performed by temporarily irradiating a focused infrared beam. 3. The coating film deterioration inspection method according to claim 1, wherein the non-contact measurement step is performed by an infrared imaging device that detects infrared rays in a wavelength band of 3 μm to 6 μm or a wavelength band of 8 μm to 14 μm. 4. The deteriorated portion determining step measures the maximum temperature and the minimum temperature in the same infrared image in a predetermined field of view, and the temperature difference is a predetermined temperature or a time point when the temperature difference becomes maximum. The coating film deterioration inspection method according to claim 1, wherein the temperature distribution image of (1) is used as a target. 5. An infrared projector for projecting infrared rays onto a coating film to be inspected, an infrared telescope for capturing the coating film to be inspected, and an infrared image device for measuring the temperature distribution of the coating film to be inspected. An infrared image processing device for determining a deteriorated portion from the temperature distribution of the coating film to be inspected, the coating film deterioration inspection device. 6. The coating film deterioration inspection device according to claim 5, wherein the infrared projection device is incorporated in the infrared telescope and is a coaxial illumination. 7. The coating film deterioration inspection apparatus according to claim 5, wherein the infrared telescope is a reflection type telescope equipped with a low magnification telescope for capturing a coating film to be inspected. 8. The infrared image processing device includes a measurement visual field limiting circuit for cutting out a video output from the infrared video device, and a detection circuit for detecting a maximum temperature and a minimum temperature in the measurement visual field. An arithmetic circuit for calculating the temperature difference of the minimum temperature, a comparison circuit for comparing the temperature registered in advance with the temperature difference, a circuit for freezing an infrared image based on the output of the comparison circuit, and a freeze time of the circuit. The coating film deterioration inspection device according to claim 5, further comprising a trigger output circuit for notifying the outside of the coating film. 9. The coating film deterioration inspection device according to claim 8, further comprising a function of stopping the light emission of the infrared light projecting device by a trigger output from the infrared image processing device.