JPS61228307A - Apparatus for ultrasonic thickness measurement of material to be inspected with coating - Google Patents

Abstract

PURPOSE:To make it possible to measure the thickness of a material to be inspected with coating with high accuracy, by determining an echo start point and an echo finish point necessary for the measurement of the thickness of the material to be inspected by detecting a boundary surface echo and a bottom surface echo. CONSTITUTION:Fundamentally, the title apparatus consists of a start point and finish point determination circuit 11 for setting the start and finish points of an echo, a measuring circuit 21 for calculating the wall thickness of a material to be inspected and a display means and the start point and finish point determination circuit 1 has a boundary surface echo automatic zero gate circuit 12 for automatically setting the zero point on the boundary surface of a boundary surface echo and a boundary surface echo automatic zero gate circuit 12 for automatically setting the zero point on the boundary surface of a boundary surface echo and a boundary surface echo height control circuit 14 consisting of an inverse DAC circuit 16 and a partial AGC circuit 18. The partial AGC circuit 18 has sensitivity control function for automatically making an echo height constant and automatically sets the start point of the boundary surface echo in connection with the automatic zero gate circuit 12 and the inverse DAC circuit 16. By this mechanism, the finish point of the bottom echo of a material to be inspected can be certainly detected even if the surface state of coating changes and highly accurate measurement is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic thickness measuring device that uses ultrasonic waves to measure the thickness of a coated material to be inspected, the surface of which is coated. In particular, the present invention relates to an ultrasonic thickness measuring device that can be suitably used to measure the thickness of a coated bottom plate of an oil storage tank for storing oil such as crude oil or heavy oil.

' Nobiso 12 Conventionally, for example, the Fire Service Act requires that the thickness of the bottom plate of a crude oil tank be measured during a periodic inspection every five years. Generally, the bottom plates of modern crude oil tanks are coated on the inside for corrosion protection, and when inspecting the bottom plate thickness, it is necessary to remove the coating layer and re-coat the bottom plate after measuring the thickness. Ru.

However, the coating materials used these days are expected to last more than 15 years, and removing such coating materials and recoating every five years is not only laborious but also requires inspection. This resulted in a significant increase in the construction period and associated costs.

Currently, various methods and devices have been proposed for measuring the thickness of the bottom plate of a crude oil tank. The most common method is to use an ultrasonic thickness gauge. The basic function of an ultrasonic thickness gage is time difference measurement using pulse reflection, which includes (1) a method of measuring the time from the pulse input to the first reflected wave, and (2) a method of measuring the time from the pulse input to the first reflected wave. There is a method of measuring the average value over time and displaying it as thickness, but when using such an ultrasonic thickness gauge for a coated tank bottom plate, the first reflected wave may be obtained depending on the coating thickness. The disadvantage is that only the coating thickness can be displayed because of the In addition, even if the first reflection is obtained at the bottom surface of the bottom plate after passing through the coating part, the value of (coating thickness) + (bottom plate thickness) is only obtained. Because the sound velocity of the material changes, the result will not be accurate (coating thickness) + (bottom plate thickness).Therefore, even with the method using an ultrasonic thickness gauge, the coating layer must be peeled off when measuring the tank bottom plate thickness. The surface of the bottom plate was forced to be exposed.

Recently, a method of measuring thickness using electromagnetic ultrasonic waves has been developed to improve the drawbacks of the above-mentioned ultrasonic thickness gauges. In this method, a static magnetic field is applied to the material to be inspected, and a high-frequency pulse is passed through a transmitter coil in the probe (sensor). Eddy currents are generated on the surface of the material to be inspected, and the action of the eddy currents and the static magnetic field generates a Lorentz force. This is based on the principle that ultrasonic vibrations are generated and transmitted inside the material to be inspected, and this propagation is reflected at the bottom surface and transmitted to the receiving coil with the opposite effect to that at the time of transmission.

As understood from its basic principle, this electromagnetic ultrasonic thickness gauge does not require the probe to be in contact with the material being inspected.
Moreover, since the coating material is not magnetized, it is possible to completely ignore the coating thickness and measure only the thickness of the bottom plate, which can be said to be superior to the above thickness gauge.

However, with the current technology of electromagnetic ultrasonic thickness gauges, the probe size cannot be reduced to less than 50 mm in diameter (the probe diameter of conventional ultrasonic thickness gauges is 10 mm).
There are limits to the measurable thickness measurement range and coating thickness. Furthermore, considering the directivity of the sound waves, using a probe that is five times larger than the conventional probe
This method has the disadvantage that accurate thickness measurements cannot be made if the back surface of the material to be inspected is corroded.

As a result of conducting research and experiments to improve the conventional methods and devices described above, the inventors improved the ultrasonic flaw detector that has been widely used for various purposes, and improved the boundaries between the coating and the material to be inspected. It has been found that the thickness of a coated material to be inspected can be accurately measured by measuring from the rising point of the reflected echo from the surface to the rising point of the first reflected echo on the surface of the inspected material. The present invention is based on this new knowledge.

l121J Therefore, an object of the present invention is to provide an ultrasonic thickness measuring device that can accurately measure the thickness of a coated material to be inspected.

F0?8. Soil to decide] The above objectives are fully achieved by the present invention.

In summary, the present invention has a probe that comes into contact with a coated material to be inspected, and the interface echo from the interface between the coating and the material to be inspected is transmitted via the probe to the bottom surface of the material to be inspected. and an ultrasonic flaw detector that receives bottom echoes from the defective part, and a wall thickness measuring device that measures the thickness of the material to be inspected, and the wall thickness measuring device includes a A circuit that receives an echo signal, detects the boundary surface echo, and sets an echo starting point for measuring the thickness of the inspected material, and a circuit that detects the bottom echo and sets an echo end point for measuring the thickness of the inspected material. This is an ultrasonic thickness measuring device for a coated material to be inspected, comprising a circuit for measuring the thickness of the material to be inspected using a starting point and an end point setting signal from the circuit.

According to another aspect, the measuring device of the present invention is further provided with a peeling detection circuit for detecting peeling between the coating and the material to be inspected.

Next, the ultrasonic thickness measuring device for coated materials to be inspected according to the present invention will be explained in more detail with reference to the drawings.

FIG. 5 explains the principle of a general ultrasonic flaw detector, showing a state in which a probe 4 is attached to a coated material to be inspected 3 and an echo detected by the probe 4. show,
In other words, when measuring the thickness of a coated inspected material 3 with an ultrasonic flaw detector, the probe 4 is installed on the coating 3a side of the inspected material 3b whose surface is coated with the coating 3a. When an ultrasonic wave is emitted from the probe 4, an echo A is received by the probe 4. The echo A includes a transmitted pulse echo5. An interface echo 6 generated at the interface between the coating 3a and the material to be inspected 3b, a bottom echo 7 generated at the bottom surface of the material to be inspected 3b, and furthermore, if a defect exists in the material to be inspected 3b, the The defect echo 8 from the defective portion is included. In this specification, both the bottom echo and the defect echo are referred to as the bottom echo 7.

However, when conventional ultrasonic flaw detectors are used to measure the thickness of coated materials to be inspected, they have the following drawbacks. First, there is no gate that captures the boundary surface knee 6 and the bottom surface echo 7 at two levels, and measurement errors occur when the starting point of the boundary surface echo changes depending on the thickness of the coating 3a. Second, the height of the boundary surface echo is lower than that of the bottom surface echo, and the height of the bottom knee 7 of the inspected material 3b changes depending on the material and surface condition of the coating 3a, and this change affects the thickness measurement accuracy. effect.

The present invention solves the above-mentioned drawbacks of the general ultrasonic flaw detector with an ultrasonic thickness measuring device that is constructed by adding a wall thickness measuring device to the ultrasonic flaw detector.

Next, the ultrasonic thickness measuring device 1 for coated materials to be inspected according to the present invention will be explained with reference to FIGS. 2 to 4.

As shown in FIGS. 1 and 2, according to the present invention, a thickness measuring device io is further added to a general ultrasonic flaw detector 2.

The ultrasonic flaw detector 2 has a normal configuration, and includes a probe (not shown) that comes into contact with the coated material to be inspected, an oscillator, a timing controller, etc., and detects the coating through the probe. This is an ultrasonic flaw detector that receives interface echoes from the interface with the inspected material and bottom echoes from the bottom surface and defective parts of the inspected material. Such ultrasonic flaw detectors are well known to those skilled in the art and no further explanation is necessary.

As shown in FIG. 1, the wall thickness measuring device IO basically includes a starting point and ending point determining circuit 11 that sets the starting point and ending point of the echo, and a measuring circuit 21 that calculates the wall thickness of the material to be inspected.
A display means for displaying the measurement results, that is, a digital printer 26, a printer control circuit 24, a digital display circuit 22, an alarm 30 and a buzzer 32 are provided.

The start point and end point determination circuit 11 includes an auto zero gate circuit 12 that automatically sets the zero point of the boundary surface of the boundary surface echo, and an inverse D
The interface echo height control circuit 14 includes an AC circuit 16 and a partial AGC circuit 18.

Moreover, it would be preferable that the power supply circuit 20 is independently installed in the wall thickness measuring device 1°.Furthermore, according to another uninvented aspect, a peeling detection circuit 28 is further provided for the purpose described below. will be placed.

As described above, the ultrasonic thickness measuring device 1 for a coated inspected material according to the present invention uses two gates G1. G2 (Fig. 6), and as shown in Fig. 7, it also has a function to automatically detect the echo starting point (zero point) necessary for measuring the thickness of the inspected material 3b. Coating 3ac7) A feature of this coating is that it enables accurate thickness measurement of the inspected material 3b even if the thickness changes.

The inverse DAC (distance amplitude compensation) circuit 16, as shown in FIG.
It has a function that can be adjusted to increase the echo height of only a portion of the boundary surface echo 6 (up to 3 mm from the starting point) and then lower the sensitivity to normal or lower.

Partial AGC (auto gain control) circuit 18
has a sensitivity adjustment function that automatically keeps the echo height constant, and has the auto zero gate circuit 12 and the inverse DAC circuit 16.
The start point of the boundary surface echo is automatically set in collaboration with the robot, and therefore, even if the surface condition of the coating 3a changes, the end point of the bottom surface echo 7 of the inspected material can be reliably detected.
Highly accurate measurement becomes possible. Further, the partial AGC circuit 1
As shown in FIG. 9, the function of circuit 8 is to prevent the reflected echo from attenuating due to poor contact between the probe 4 and the material to be inspected 3a. echo 7
The point is that it only affects

According to one aspect of the invention, the thickness measurement and display device 1 is provided with a peel detection circuit 28. The circuit 28, as illustrated in FIGS. 10 to 12, is configured to set and output a gate that captures the bottom echo of the inspected material 3. When there is no peeling 8 between the coating 3a and the material to be inspected 3b, a bottom echo 7 is detected as shown in FIG. 11, but when there is a peeling 8 between the coating 3a and the material to be inspected 3b. As shown in FIG. 12, the bottom echo 7 is not detected.

The operation of this device will be explained with reference to the first TIIJ, FIG. 3, FIG. 4, and FIG. 6.

To measure the thickness, first a master trigger is generated from the ultrasonic flaw detector 1 to start its operation. The master trigger is called a pulse repetition frequency, and the master trigger applied to the probe 4 is normally set to 500 to 1OOOH2.

When ultrasonic waves are emitted from the probe 4 into the inspected material 3,
Echo A is received by the probe 4 . The echo A includes a transmitted pulse echo5. Boundary echo 6 generated at the interface between coating 3a and inspected material 3b and inspected material 3b
Furthermore, if there is a defect in the inspected material 3b, a defect echo 8 is generated from the defective part.
is included.

Gate G generated by master trigger from flaw detector 1
l specifies the starting point range and appears in this range. AG
The processed boundary reflection echo 6 is detected by the C circuit 18, and the starting point of the boundary surface echo is set. The gate G2 is set by a gate signal from the flaw detector 1, detects the bottom echo 7 from the probe, and sets the end point.

In determining the starting point and ending point for measurement in G1 and G2, the boundary echo auto zero gate circuit 12
As described above, the boundary surface echo height control circuit 14, that is, the inverse DAC circuit 16 and the partial AGC circuit 18 function effectively.

When the starting point and ending point for thickness measurement are determined with the above configuration, the measuring circuit 21 measures the time between both pulses and calculates the thickness of the inspected material 3b. That is, the game specified by the gain control function) G1. The starting point and ending point of thickness measurement determined by G2 are sent to the measurement circuit 21 as electrical signals, and then the digital display circuit 22 converts the voltage between the starting point and the ending point (T/A output), and converts it into a digital signal. A/D conversion), the thickness of the inspected material 3b is displayed digitally. The digital signal is stored in a storage device (not shown) and is sent to the printer control circuit 2 as necessary.
4 and the digital printer 26.

When the measurement is completed, it is reset and the next measurement is automatically carried out according to the above procedure.

An alarm 30 and a buzzer 32 made of light emitting diodes light up and issue an alarm when the peeling detection circuit 28 detects a peeled portion.

Each of the circuits and devices described above can receive necessary power from an independently provided power supply circuit 20 without using the power supply of the flaw detector 2.

FIG. 13 shows an example of a specific electric circuit of the ultrasonic thickness measuring device for coated materials to be inspected according to the present invention. In this example, a boundary surface detection gate circuit A, a starting point・
The end point detection circuit B and the partial AGC circuit C include the above-mentioned boundary echo auto zero gate circuit 12 and the boundary echo height control circuit 14, that is, the inverse DAC circuit 16 and the partial AGC circuit 12 and the boundary echo height control circuit 14.
It will be understood that the circuit 18 is configured to effectively set the starting point of the boundary echo and the ending point of the bottom echo, and the measuring circuit 21 is arranged in the starting point/end point detection circuit B in this embodiment. It will be seen that this is achieved by the flip-flop circuit B1, which is connected to a T/A converter circuit and an A/D converter circuit E having a normal configuration.

It is also clear that the peel detection circuit F is activated by the trigger signal from the boundary surface detection gate circuit and the AGC-processed echo signal.

It is believed that the structure and operation of the present invention will be easily understood by those skilled in the art based on the brief explanation of the above electric circuit diagram and FIG. 13, and therefore further detailed explanation of the circuit diagram will be omitted.

Furthermore, the configuration of the present invention is not limited to the electric circuit diagram of FIG. 13, and various other electric circuits may be conceived within the scope of the present invention.

The ultrasonic thickness measuring device for a coated inspected material according to the present invention is constructed and operated as described above, and thus can accurately measure the thickness of a coated inspected material.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the operation of the ultrasonic thickness measuring device for a coated inspected material according to the present invention. FIG. 2 is a schematic perspective view of an apparatus for measuring the ultrasonic thickness of a coated material to be inspected according to the present invention. FIGS. 3 and 4 are explanatory diagrams illustrating the operation of the ultrasonic thickness measuring device for a coated inspected material according to the present invention. FIG. 5 is a diagram illustrating how echoes are generated in the ultrasonic flaw detector. 6 and 7 show an auto-zero gate circuit, an inverse DAC circuit and a partial AG circuit for determining the start and end points of echoes.
It is a schematic diagram explaining operation of C circuit. FIG. 8 is a diagram illustrating the operation of the inverse DAC circuit. FIG. 9 is a diagram illustrating the operation of the partial AGC circuit. 10 to 12 are diagrams for explaining the operation of the peeling detection circuit. FIG. 13 is a wiring diagram of a specific electric circuit of the ultrasonic thickness measuring device for a coated inspected material according to the present invention. 2: Ultrasonic flaw detector 3: Coating material Inspected material 3a: Coating 3b: Inspected material 4: Probe 5: Transmission pulse echo 6: Boundary echo 7: Bottom echo 8: Defect echo IO: Thickness measuring device 11: Start point and end point determination circuit 12 Two-to-one zero gate circuit 14: Boundary surface echo height control circuit 16: Reverse DAC circuit 18: Partial AGC circuit 20: Power supply circuit 22: Digital display circuit 24: Printer control circuit 26: Digital printer 28: Peeling detection circuit 30: Alarm 30 32: Buzzer 32 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 (Friend) i#) Procedural correction tooth [
Method] July 23, 1985 Michibu Uga, Commissioner of the Japan Patent Office Display of the case 1985 Patent Application No. 69727 Name of the invention Case of a person who corrects an ultrasonic thickness measuring device for coated inspected materials Related Patent Applicant: Suzue Building (Telephone: 459-8309) June 25, 1985 (shipment date) (2) Drawings (plans)

Claims (1)

[Claims] 1) It has a probe that comes into contact with the coated material to be inspected, and the interface echo from the interface between the coating and the material to be inspected and the material to be inspected are transmitted through the probe. It is equipped with an ultrasonic flaw detector that receives bottom echoes from the bottom surface and the defective part, and a wall thickness measuring device that measures the thickness of the material to be inspected, and the wall thickness measuring device includes a a circuit that receives an echo signal from the interface, detects the boundary surface echo, and sets an echo starting point for measuring the thickness of the inspected material; and a circuit that detects the bottom echo and sets an echo ending point for measuring the thickness of the inspected material. The circuit to be set and
1. An ultrasonic thickness measuring device for a coated material to be inspected, comprising: a measurement circuit for measuring the thickness of the material to be inspected based on start point and end point setting signals from the circuit. 2) It has a probe that comes into contact with the coated material to be inspected, and detects boundary echoes from the interface between the coating and the material to be inspected and echoes from the bottom surface of the material to be inspected and defects through the probe. It is equipped with an ultrasonic flaw detector that receives bottom echoes, and a wall thickness measuring device that measures the thickness of a material to be inspected, and the wall thickness measuring device receives echo signals from the ultrasonic flaw detector and detects the a circuit that detects an interface echo and sets an echo starting point for measuring the thickness of the inspected material; a circuit that detects the bottom echo and sets an echo end point for measuring the thickness of the inspected material;
A coated material comprising: a measuring circuit for measuring the thickness of a material to be inspected based on start point and end point setting signals from the circuit; and a peeling detection circuit for detecting peeling between the coating and the material to be inspected. Ultrasonic thickness measuring device for inspection materials.