JPS62140010A - Method for measuring thickness of coated film and member to be coated by ultrasonic wave - Google Patents

Abstract

PURPOSE:To make it possible to measure the thicknesses of the titled film and a member, by allowing an ultrasonic wave to be vertically incident upon the coated surface of a painting member and measuring the receiving times of an echo once reflected and an echo twice reflected from a bottom surface. CONSTITUTION:A vertical probe is brought to a contact with the coating surface 3 of a member M and an ultrasonic wave is allowed to be vertically incident upon the surface 3 and the reflected wave is received through the probe and the echo thereof is displayed on a CRT. Whereupon, a first bottom surface echo (B1) of the reflected wave B1, which is obtained by reflecting said ultrasonic wave from the bottom surface 8 of a member 1 through the boundary surface 7 of the member 1 and the film 2 and again passing the reflected wave through the surface 7, is displayed at the position of a receiving time T1 from the origin of an abscissa (time axis). Thereafter, the second bottom surface echo (B2) of a reflected wave B2, which is obtained by reflecting the ultrasonic wave from the surface 8 through the surface 7 to reflect the reflected wave from the surface and again reflecting the reflected wave from the surface 8 to pass the same through the surface, is displayed at a position where a receiving time T2 has elapsed. Then, by performing a predetermined calculation on the basis of the preliminarily measured sound velocities in the member 1 and the film 2 and the times T1, T2, the thicknesses t2, t1 of the film 2 and the member 1 can be simultaneously measured.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of measuring the coating film of a painted member on the surface of the member and each thickness of the member using ultrasonic waves. This method is suitable for measuring the thickness of a coating film and a member at the same time.

[Background of the invention]

It has been widely used to measure the thickness of an object and the degree of corrosion from changes in thickness using ultrasonic waves. In other words, it is measured using an ultrasonic thickness meter that utilizes the resonance of ultrasonic waves within the board.The thickness of the board can be determined from the time interval of multiple reflections of pulses in the board, and the attenuation of multiple reflections can be used to determine the thickness of tanks, pipes, etc. Pulse method for estimating the corrosion status of the back surface (for example, Japan Society for the Promotion of Science, “Ultrasonic Flaw Detection Method J”, 198
4), Nikkan Kogyo Shimbun, P571-P577) is also common. However, when measuring the thickness of a component using these methods, if the component is a painted component, the attenuation of the ultrasonic waves by the coating is large, and the true Since resonance and multiple reflected wave intervals cannot be obtained, measurements are inevitably made with large errors.For this reason, conventionally, measurements are taken after removing the paint film at the measurement position. Removal of the paint film requires a huge amount of work when measuring doll tanks or many long pipelines, and is a major hindrance to measurements. In this way, when measuring the thickness of painted parts using conventional ultrasonic waves, it is only possible to measure the thickness of the part after the paint film has been removed. It was not possible to measure the thickness of the member and the thickness of the coating film in the unpainted state of the member.

Measuring only the thickness of the coating film is possible with a coating meter that utilizes the electromagnetic induction effect between a coil through which alternating current is passed and the metal to be inspected, but the metal to be inspected may be a magnetic material such as steel. However, there are problems such as the measurement value needs to be compared with a calibration value and the accuracy is not sufficient.

[Purpose of the invention]

The present invention solves the problems of the prior art described above, and uses ultrasonic waves to measure the coating film of a painted member and each thickness of the member from above the coating film without removing the coating film. It is an object of the present invention to provide a method that allows measurement to be performed easily, quantitatively, accurately, and in real time without being influenced by the material, shape, roughness, etc. of the bottom surface.

[Summary of the invention]

The present invention is a method for measuring the coating film of a painted member whose surface is coated with paint and the respective thicknesses of the member. The waves pass through the interface between the coating film and the component and are reflected at the bottom of the coating component.
The first bottom echo received after passing through the boundary surface again, and the reflected wave that passed through the boundary surface and reflected at the bottom surface of the painted member are reflected at the boundary surface and reflected again at the bottom surface of the painted member. The coating film of the painted member and the thickness of the member are measured using each reception time of the second bottom echo received after passing through the boundary surface and the sound velocity of the coating film and the member as evaluation indicators. By this, the coating film of the painted part and the thickness of each part,
This method allows for easy, quantitative, and real-time measurement on the paint film without removing the paint film, without being affected by the material of the component, the shape of the bottom surface, roughness, etc. .

[Embodiments of the invention]

Embodiments of the present invention will be explained with reference to FIGS. 1 to 6.

As shown in FIG. 2, a vertical probe (hereinafter referred to as a probe) is placed on the painted surface 3 of the painted member M on which paint is applied to the surface of the member 1 (which becomes the boundary surface 7) to form the coating film 2. 4 and make ultrasonic waves perpendicular to the painted surface 3. 5 is probe 4
A pulse reflection type ultrasonic flaw detector is connected to the CRT by a high frequency cable, and 6 is its CRT. The incident ultrasonic wave is caused by the difference in acoustic impedance between the member 1 and the coating film 2.
As shown in the figure, various forms of reflected waves result. That is, A is a reflected wave reflected from the boundary surface 7 between the member 1 having a thickness of tl and the coating film 2 having a thickness tl, B passes through the boundary surface 7, is reflected by the bottom surface 8 of the member 1, and is reflected by the boundary surface 7 again. The reflected wave that passed through B, A is the reflected wave that reflected the reflected wave B on the painted surface 3 and then reflected on the boundary surface 7, A B + is the reflected wave that was reflected on the painted surface 3 and then the reflected wave layer. A reflected wave following the same course, B2, passes through the boundary surface 7, is reflected at the bottom surface 8 of the member 1, is reflected at the boundary surface 7, is reflected again at the bottom surface 8 of the member 1, and has passed through the boundary surface 7. B3 is a reflected wave that has been reflected by the reflected wave B on the painted surface 3 and then made one more round trip between the painted surface 3 and the bottom surface 8. Each reflected wave is received via the probe 4 and is subjected to multiple reflections and is attenuated. When the echoes of the received reflected waves are displayed on the CRT 6, echo patterns as shown in FIGS. 3 and 4 are obtained. Figure 3 shows the case where the probe 3 is a split type, and the horizontal axis (time axis) shows the S echo of the surface reflected wave reflected from the painted surface 3 near the origin, and the beam path X from the origin at the reception time T. , the first bottom echo of the reflected wave B1 (03+), the first bottom echo (B1
), the second bottom echo (B2) of the reflected wave B2 is displayed at the position of the beam path x2 after the reception time T2 has elapsed. Also, Figure 4 shows the case where the probe 3 is used for both normal transmitting and receiving purposes, and compared to Figure 3, the transmitted pulse T is displayed at the origin of the horizontal axis, and the heights of the echoes B+) and (B2) are somewhat lower. Otherwise, the beam path lengths x and +XZ are the same. As shown in Figures 3 and 11, the echoes of each reflected wave displayed on the CRTS are narrowed down to the first back-wall echo (B1) and the second back-wall echo (B2) because (1) ,
The thickness tl of the coating film 2 is as thin as approximately 1 mm or less except in special cases, and the echo of the reflected wave A is an S echo or a transmitted pulse T.
There is almost no difference on the time axis.

(2) For the same reason as (1), reflected waves B, A, AB
.

There is also almost no difference on the time axis between the echo of the reflected wave B3 and the first bottom echo (B+), and the echo of the reflected wave B3 and the second bottom echo (B2). (3), the echo of reflected wave B3 and the second
Comparing the sound pressure of the bottom surface echo (B2), it is found that the sound pressure round trip rate decreases at the boundary surface 7 due to the difference in acoustic impedance between the member 1 and the coating film 2. The echo of the reflected wave B3 is considerably lower. Due to reasons such as.

The sound velocities of member 1 and coating film 2 are measured in advance, and if the sound velocity of member 1 is CI + the sound velocity of coating film 2 is 02, then
The thickness tl of the member 1 and the thickness tl of the coating film 2 are determined by the following equations.

tl=c,・T2 ・・・・・・・・・(1)t
2=Cz (TI-T2) ・・・・・・・・・
(2) Also, if the time axis on the CRTe is set as shown in FIG.
(2) Chopsticks I”X2 ・・・・・・・・・・・・
... (3) tz=cz (XI X2) /C
I can be transformed into (4).

Therefore, by reading the scale on the time axis of the echo displayed on the CRTe from equations (3) and (4) and performing simple calculations using the above equation, it is easy to calculate the coating film of the painted member and each thickness of the member. can be measured simultaneously. In addition, without displaying it on the CRTe, the analog quantities of the reception times TI and T2 of each echo are digitized by commonly used means, and the equation (
It is also possible to calculate by 1) and (2) and display the numerical value.

Next, specific examples measured using the present invention will be explained with reference to FIGS. 5 and 6. FIG. 5 is a graph showing the results of measuring the thickness of each steel plate when a plurality of steel plates having different thicknesses were coated with a substantially constant coating thickness. The steel plate has a thickness of 4.6°8.10.12 (unit: mm).
Each steel plate is coated with epoxy tar paint on one side to a uniform thickness of approximately 150 μm. When each measured value (unit: mm) is plotted, the horizontal axis is the thickness of the steel plate determined with a micrometer before painting, and the vertical axis is the thickness of the steel plate measured by the method of the present invention.1 Each measured value of both is It can be seen that there is almost perfect agreement and that measurement can be performed with high accuracy.

FIG. 6 is a graph in which the thickness of each coating film is determined by 111 when coating a steel plate with a constant thickness with varying coating thicknesses. This is a measurement of four steel plates with a thickness of 4 mm each coated with epoxy tar paint on one side at different thicknesses of approximately 70.150°300 and 500 (unit: μm), and the horizontal axis is the cut surface. The thickness of the coating film was measured using a microscope, and the vertical axis is based on the method of the present invention. When each measured value (unit: nn) was measured from 1 to 1, the measured values of the two coincided well, proving that highly accurate measurement could be performed.

This method does not evaluate echo height.

Since the echo reception time (beam path) is used as an evaluation index, even if the shape of the bottom surface 8 of the member 1 changes due to corrosion or becomes rough, it will not be affected by the change in shape. , and as long as the object can propagate ultrasonic waves, it will not be affected by the material, regardless of whether it is magnetic or non-magnetic.

Therefore, for example, the degree of corrosion and the distribution of corrosion on parts with a coating thickness of 9 and 2, such as large tanks and pipelines, can be easily and accurately measured from the painted surface in real time, and the probe can be moved over the painted surface. It is also possible to continuously determine alff simply by

In the embodiments, a direct contact method in which the probe is brought into contact with the painted surface has been described, but it goes without saying that the immersion method can also produce similar effects and effects.

〔Effect of the invention〕

As explained above, the present invention allows ultrasonic waves to be incident perpendicularly to the painted surface of a painted member, and the incident wave is reflected and received by the bottom surface of the member, which is the first bottom echo, and the bottom surface of the member receives two echoes.
Since each thickness of the coating film of the painted member and each member is measured using each reception time of the second bottom echo that is reflected and received twice and each sound velocity of the coating film and member as evaluation indicators, the above-mentioned This has a practical effect of being able to easily and quantitatively measure each thickness from the coating film, without being affected by the material of the member, the shape of the bottom surface, etc., and in real time.

[Brief explanation of drawings]

The figures are detailed explanatory diagrams of the present invention, Fig. 1 is a diagram showing the generation of various forms of reflected waves when ultrasonic waves are incident on a painted member, Fig. 2 is an overall explanatory diagram of the measurement method, Figure 3 is a diagram showing an example of an echo pattern on a CRT when a split vertical probe is used, and Figure 4 is an example of an echo pattern on a CRT when a vertical probe for transmitting and receiving purposes is used. FIG. 5 is a graph example of a specific measurement result of the thickness of a coated member, and FIG. 6 is a graph example of a specific measurement result of the thickness of a coating film of a coated member. 1... Member, 2... Paint film, 3... Painted surface, 4...
・Vertical probe, 6... CRT, 7... Boundary surface, 8.
・・Bottom surface, (B+)・・1st bottom surface echo, (B2)・
...Second bottom echo, T I + T 2...Reception time, M...Painted parts.

Claims (1)

[Claims] 1. A method of measuring the coating film of a painted part with paint applied to the part surface and each thickness of the part, in which ultrasonic waves are incident perpendicularly to the painted surface of the painted part, and the incident waves are used to measure the thickness of the painted part. and a first bottom echo that is received after passing through the boundary surface of the painted member, being reflected at the bottom surface of the painted member, and passing through the boundary surface again;
A reflected wave that passes through the boundary surface and is reflected on the bottom surface of the painted member is reflected on the boundary surface, is reflected again on the bottom surface of the painted member, and is received after passing through the boundary surface and is a second bottom echo. A method of measuring the thickness of the coating film of a painted member and each member using the respective reception times of and the sound velocities of the coating film and the member as evaluation indicators.