JPH0422446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-contact coating inspection device for inspecting the coating condition of a surface of a metal material, for example.

[Conventional technology]

BACKGROUND ART Conventionally, in coating inspections of metal surfaces, such as penstocks, etc., human beings visually observe the surface and judge the lifting, peeling, etc. of the coating film based on its unevenness, color, etc. After making this determination, particularly suspicious areas are manually pressed to check whether the paint film has lifted or not.

As another inspection method, there is a method of inspecting the peeling state of the paint film by ultrasonic flaw detection using a probe.

[Problem that the invention seeks to solve]

With conventional visual inspection methods, if the paint film is slightly floating, it is almost impossible to tell just by pressing it down manually, and it is also dependent on the subjectivity of the inspector to obtain an accurate judgment. That's difficult. Another problem is that it cannot be tested in areas that are inaccessible to humans due to environmental and safety concerns.

Furthermore, the inspection method using ultrasonic flaw detection is not only not suitable for areas where the paint film has peeled off, but also when there is an acoustic medium such as water between the metal surface and the paint film, or if the paint film is lifted due to the pressure of the probe. It has the disadvantage that errors are likely to occur when there is no upstream. In addition, the probe must be brought into contact with the paint film during measurement, which causes problems such as the peeled portion becoming larger and the painted surface being damaged.

The present invention has been made to solve these problems, and an object of the present invention is to provide a non-contact coating inspection device that can efficiently and accurately measure the lifting and peeling of a coating film in a non-contact manner.

[Means for solving the problem] The non-contact coating inspection according to the present invention heats the coating film applied to the member using dielectric heating means to create a thermal diffusion state that changes depending on the state of the coating film, and then uses infrared rays to The coating condition is inspected by detecting it with a camera and displaying it as a temperature distribution image.

[Effect]

In this invention, the paint film is heated directly and uniformly by a dielectric heating means to create a heat diffusion state that changes depending on the difference in heat transfer coefficient between defective parts and normal parts of the paint film, and by detecting this state, the paint film is to be inspected without contact.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 1 is an object (member) to be painted such as a steel plate or steel pipe, 2 is a paint sprayed or applied onto the surface of the object 1, and Thereafter, the coating film 2a is formed to a predetermined thickness by baking or as it is.
The peeled part is shown. 3 indicates a dielectric heating means, which is a dielectric heating device 4 that outputs a high frequency signal.
and a dielectric electrode 5 which receives a high frequency signal from the dielectric heating device 4 and applies a high frequency electric field to the coating film 2. Reference numeral 6 denotes an infrared camera arranged at a constant interval in parallel with the dielectric heating means in a direction perpendicular to the surface of the coating film 2. 7 is a control section, and the dielectric heating means 3, the infrared camera 6, and the control section 7 are placed on a self-propelled trolley (not shown) and run at a predetermined speed in the direction of arrow A shown in the figure. Since this moving speed is not necessarily constant, the heating of the dielectric heating means 3 and the infrared camera 6 are controlled depending on the speed. That is, a control signal is given to the dielectric heating device 4 to increase the heating temperature by the dielectric heating means 3 in proportion to the traveling speed detected by the speedometer 8, thereby controlling the electric field strength and controlling the scanning speed of the infrared camera 6. do. Therefore, when the truck speed is determined in advance, the control section 7 only needs to control based on the already known truck speed, and in this case, the speedometer 8
is not necessarily necessary. 9 is a signal processing unit which obtains one two-dimensional temperature distribution image from the output data from the infrared camera 6 and the scanning timing output from the control unit 7, and displays the image on the CRT display 1.
0 and a video recorder 11. That is, the output data of the infrared camera 6 is converted into binary data or digital data with a gradation difference, stored in an image memory (not shown), read out according to the scanning timing from the control unit 7, converted into analog data, and then modulated in brightness. After converting it into a signal or a color display signal, it is outputted to a CRT display 10 for display, and also outputted to a video recorder 11 for recording. Note that the above-mentioned scanning timing is a factor for control in order to obtain two-dimensional images one by one, that is, to keep the number of images per traveling distance constant and view them in real time.

Next, the operation of the non-contact coating inspection device configured as described above will be explained. The entire device, including or excluding the CRT display 10 and video recorder 11, is remounted on the self-propelled trolley, and with the dielectric electrode 5 separated by a predetermined distance from the surface of the coating film 2, it is moved in the direction of arrow A in FIG. move it.

During this movement, the control unit 7 controls the object 1 to be coated including the coating film 2 measured by the infrared camera 6.
captures the temperature signal. At this time, the control section 7 controls the dielectric heating means 3 and the infrared camera based on the speed signal from the speedometer 8 or a speed signal that can be known in advance. That is, a control current is passed through the dielectric heating device 4 to apply a high frequency uniform high electric field to the coating film 2 from the dielectric electrode 5. Since the coating film 2 is made of a dielectric material, it is heated uniformly by a uniform high electric field, and the heat generated by this heating is diffused into the object 1 to be coated.

Now, as shown in FIG. 1, if a peeled part 2a has occurred in the paint film 2, the heat transfer coefficient between the paint film 2 at the peeled part 2a and the object 1 to be painted is equal to the heat transfer rate of the object 1, which is a metal material. Since it is smaller than the transfer rate, the thermal diffusion state is different from that of the non-separated portion, and the temperature of the peeled portion 2a becomes higher than the temperature of other normal portions. For example, the outside temperature is 20
℃, if the heating temperature is set to 50℃ and there is a temperature difference of 30℃ from the outside air, the peeled part 2
A temperature difference of about 6° C. appears between a and the non-peeled portion. Note that when the moving speed of the device is fast, the control section 7 controls the heating temperature by the dielectric heating means 3 in proportion to the speed in order to ensure the heating temperature.

After heat diffusion is caused by the dielectric heating means 3 in this manner, the temperature is measured by the infrared camera 6 and this temperature signal is sent to the signal processing section 9. Then, in the signal processing section 9, one two-dimensional temperature distribution image is constructed according to the scanning timing sent from the control section 7, and the CRT display 10
and is recorded on the video recorder 11.

Figure 2 shows the display screen of the CRT display 10.
That is, it is a diagram showing a temperature distribution image. In the figure, M indicates a low temperature part in a normal state, and N in the figure indicates a high temperature part, which is the peeled part 2a of the coating film 2.

In this way, according to the present device, the information displayed on the CRT display 10 or the display 11
By looking at the temperature distribution image recorded in
The peeling state of the paint film 2 can be inspected with high precision.

Although the above embodiment described the case where one infrared camera 6 was used, as shown in FIG.
When two infrared cameras are arranged, a delay circuit is provided between the control section 7 and the signal processing section 9. That is, a front infrared camera 12 is placed at a fixed interval in front of the dielectric heating means 3, and a delay circuit 1 that delays the temperature signal detected by the front infrared camera 12 for a fixed period of time.
3, and by measuring the temperatures before and after heat diffusion occurs by the dielectric heating means 3 and inputting them to the signal processing section 9 at the same time, it is possible to accurately inspect the coating state while removing noise components.

In other words, if Δt is the delay time, Δt=l/
It is represented by v. Here, l is the distance between cameras (constant) and v is the relative device speed at that time.
By using this Δt to calculate the difference in information from the two infrared cameras 6 and 12, highly accurate inspection results can be obtained in which the originally occurring temperature unevenness, that is, noise on the surface of the object to be inspected is removed.

Furthermore, although the above embodiments have been described with reference to the case in which the dielectric heating means 3 and the like are moved, the same effect can be obtained even if the object 1 to be coated is moved.

Furthermore, although each of the above embodiments has been described with respect to coating metal materials, the present invention can also be applied to coating plastics, wood, and the like.

〔Effect of the invention〕

As explained above, this invention uses an infrared camera to detect changes in the thermal diffusion state caused by changes in the state of the paint film by directly and uniformly heating the paint film using a dielectric heating means, and displays a temperature distribution image. This has the effect that lifting and peeling of the paint film can be detected efficiently and accurately in a non-contact manner.

Furthermore, since the coating film itself is directly heated, it can be heated in an extremely short time, and it also has the effect of reducing the electric capacity required for heating.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of this invention.
FIG. 2 is a temperature distribution diagram of the above embodiment, and FIG. 3 is a block diagram showing another embodiment. DESCRIPTION OF SYMBOLS 1...Object to be painted, 2...Painted film, 2a...Peeled part, 3...Dielectric heating means, 4...Dielectric heating device, 5...Dielectric electrode, 6, 12...Infrared camera, 7... Control unit, 8...Speedometer, 9...Signal processing unit, 10...CRT display, 11...Video recorder, 13...Delay circuit.

Claims (1)

[Claims] 1 In a non-contact paint inspection device that inspects the condition of a paint film applied to the surface of a member, the device is installed at a certain distance from the surface of the paint film, applies a high-frequency electric field to the paint film, heats the paint film, and checks the condition of the paint film. a dielectric heating means for forming different thermal diffusion states depending on the temperature; an infrared camera disposed at a predetermined distance from the dielectric heating means for detecting the thermal diffusion state;
Control for relatively moving the above-mentioned member, dielectric heating means, and infrared camera, and controlling the output intensity of the dielectric heating means and the scanning timing of the infrared camera according to the moving speed at this time or a predetermined moving speed. and a display means for displaying a temperature distribution image using the scanning timing signal output from the control unit and the display signal output from the infrared camera. Device.