JPH04105011A - Ultrasonic thickness gauge - Google Patents

Abstract

PURPOSE:To enhance the measuring accuracy by determining a correction factor through comparison of the thickness signals given by No. 1 reference device and a reference sound speed setting device with a signal given by No. 2 reference device, and correcting the sound speed with the correction factor obtained. CONSTITUTION:An ultrasonic transfer time signal for No. 1 calibration range selected by No. 1 reference device 1 is fed to a signal converter 2, and a thickness signal obtained from the product with the sound speed given by a reference sound speed setting device 5 is emitted and displayed 4 through an A/D converter 3. Part of this thickness signal is fed to a calculating circuit 8 together with thickness signal of No. 1 calibration range selected by No. 2 reference device 7, and the two thicknesses are compared, and the result is emitted as a correction factor. The set value on the reference sound speed setting device 5 is corrected 5 with this correction factor, and the result is fed to the signal converter 2 through a changeover device 14 and a sound speed zero signal generating device 15. Then reference signal generating device of the reference devices 1, 7 is selected, and the set value on a reference zero setting device 6 is corrected. Thereby the correction factor is modified even though the characteristics of the signal converter 2 vary, and thickness measurement can be done with high precision.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an ultrasonic thickness meter that injects ultrasonic waves into a material to be tested and measures the thickness of the material based on the ultrasonic propagation time. , especially regarding the calibration of thickness gauges.

[Conventional technology j Figure 4 is a block diagram of a conventional ultrasonic thickness gauge.
A signal converter for converting a thickness measurement signal into a thickness signal, 3 is A-
D converter, 4 is a display device that displays the thickness, 11 is a sonic speed setting device, 12 is a zero setting device, 15 is a sonic speed/zero signal generator that converts the signals from the sonic speed and zero setting device, 18 is a test piece , 19 are ultrasonic probes.

Conventional ultrasonic thickness gauges are configured as described above, and are integrated with a transmitting probe that transmits ultrasonic waves and a receiving probe that receives reflected waves from the test material. A sonic probe 19 is used, and the thickness needle body is attached with a sound velocity setting device 11 and a Yazero setting device 12 for setting the sound velocity of the material to be examined.

Normally, the thickness gauge is calibrated manually prior to measuring the thickness of the material to be inspected. The ultrasonic probe 19 is alternately brought into contact with the test pieces 18 of the two types of calibration ranges that have the maximum and minimum dimensions of the measurement range at the same sound speed as the material to be measured, and the sound speed setting device 11 and zero are set accordingly. The ultrasonic thickness gauge is calibrated by repeatedly adjusting the instruments 12 so that the measured thickness can be displayed with a predetermined accuracy.

Next, the ultrasonic probe 19 is brought into contact with the specimen through the couplant. For example, echoes reflected from the surface and bottom of a flat plate-shaped test material are sent to the signal converter 2 to convert the set values of the sonic velocity setter 11 and zero setter 12 into the sound velocity/zero signal converter 15 and convert the thickness. converted into a signal and AD
The digital value from the converter 3 is displayed on the display device 4 as the thickness of the material to be inspected.

[Problem to be solved by the invention] In the conventional ultrasonic thickness gauge as described above, the ultrasonic probe 19
The echoes from the surface and bottom of the test material are applied to the signal converter 2, and the thickness obtained by multiplying the ultrasonic propagation time in the test gutter and the sound speed of the test piece 18 is output as a voltage. Ru.

The signal converter 2 is composed of, for example, an integrating circuit or a constant current circuit, and these electronic circuits are controlled by environmental conditions such as ambient temperature and humidity.
The accuracy of thickness measurement deteriorates due to the influence of changes in power supply voltage and power supply voltage.

Measurement@To improve the accuracy, the ultrasonic probe 19 is alternately brought into contact with two types of test pieces 18 in the calibration range, which are made of the same material as the material to be tested but have different thicknesses, and the corresponding sound velocity setting device 11 and zero setting are performed. Calibration is performed so that the thickness can be displayed with a predetermined accuracy by adjusting the gauge 12 alternately, but calibration takes time.Especially when calibrating a high-precision ultrasonic thickness gauge, the frequency of repetition increases, making it even more difficult. There are problems in that it takes time and quick calibration cannot be performed unless one is familiar with the operation.

This invention was made to solve this problem, and it is possible to match the set value of the sound speed setting device with the actual sound speed without being affected by changes in the surrounding environmental conditions or power supply voltage. It is an object of the present invention to provide an ultrasonic thickness gauge that can automatically and quickly perform measurement and easily ensure a predetermined measurement accuracy.

, 1 Means for Solving Problems: The ultrasonic thickness gauge according to the present invention includes a first reference device that individually generates ultrasonic propagation time signals for different calibration ranges, and a reference that sets the sound speed related to calibration. A sound velocity setting device, a second reference device that individually generates a thickness signal corresponding to a calibration range, and a thickness signal obtained from both signals of the first reference device and the reference sound velocity setting device and a second reference for the range. The system is equipped with an arithmetic circuit that compares signals from the devices and outputs a correction coefficient, and a correction circuit that corrects the sound speed set by the output of the arithmetic circuit.

[Function] In the present invention, the calibration of the ultrasonic thickness gauge that is performed prior to measuring the thickness of the material to be tested is performed using the first reference device that generates the ultrasonic propagation time signal in the calibration range and the reference sound velocity setting device. The sound speed is corrected by a correction coefficient obtained based on a comparison between the thickness signal obtained from the second standard and the signal from the second reference device, and the actual sound speed is obtained.

Even if the environmental conditions such as ambient temperature and humidity, as well as the power supply voltage, change, the ultrasonic thickness gauge can avoid these effects, improving measurement accuracy and reproducibility.

To measure the thickness of specimens with different sound velocities, just set a predetermined sound velocity and no recalibration is required.

Therefore, it is possible to accurately and efficiently measure the thickness of test materials with different measurement ranges and sound velocities.

[Embodiment] An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, 2.3.4.11.12.15.18.1
Reference numeral 9 is the same as the conventional thickness gauge described above, 1 is a first reference device that generates an ultrasonic propagation time signal for each calibration range, 5 is a reference sound velocity setting device that sets the sound velocity related to calibration, and 6 is a reference zero setting. A second reference device 8 generates a thickness signal for each calibration range, and a reference numeral 8 indicates a thickness signal obtained from the first reference device Y and the reference sound velocity setting device 5, and a signal from the second reference device E. an arithmetic circuit for comparison; 9 a first correction circuit that corrects the sound speed of the reference sound speed setting device 5 using a correction coefficient from the arithmetic circuit 8; 10 a storage circuit;
13 is a second correction circuit for correcting the sound speed of the sound speed setting device 11;
14 (first switch), 16 a second switch, and 17 a sound speed indicator.

In the ultrasonic thickness gauge configured as described above, in the calibration performed prior to thickness measurement, the first reference device 1
generates a signal with an ultrasonic propagation time corresponding to the calibration range.

FIG. 2 is a block diagram showing an embodiment of the first reference device, in which 21 is a first reference signal generator that generates an ultrasonic propagation time signal for the first calibration range, and 22 is a second calibration range. A first reference signal generator (2) generates an ultrasonic propagation time signal for the reference signal, and 23 indicates a third switch.

FIG. 3 is a block diagram showing an embodiment of the second reference device, in which 24 is a second reference signal generator that generates a thickness signal for the first calibration range, and 25 is a thickness signal for the second calibration range. The second reference signal generator (2) which generates the signal and the third switch 23 are interlocked with the switch in the first reference port.

The ultrasonic propagation time signal for the first calibration range from the first reference signal generator 21 selected by the third switch 23 in the first reference device 1 is applied to the signal converter 2 and sent from the reference sound velocity setting device 5. The thickness signal obtained by multiplying by the sound velocity is outputted as a voltage, passed through the AD converter 3, becomes a digital value, and is displayed on the display device 4.

A part of the thickness signal is sent to the third switch 23 in the second reference device.
The first signal from the second reference signal generator 24 selected by
It is applied to the arithmetic circuit 8 together with the thickness signal of the calibration range, and the two thicknesses are compared and output as a ratio, that is, a correction coefficient. The setting value of the reference sound velocity setting device 5 is corrected in the first correction circuit 9 by the correction coefficient from the calculation circuit 8, and the actual sound speed is output from the first switch 14 via the sound speed/zero signal generator 15 to the signal converter 2. added to.

Furthermore, the correction coefficients from the calculation circuit 8 are stored and stored in a memory circuit 10 using a latch circuit or the like.

Next, the third switching device 23 in the first reference device Y and the second reference device E is activated to select either the first reference signal generator lI22 or the second reference signal generator lI25, and performs the same operation as above. The set value of the reference zero setter 6 is corrected.

Even if the characteristics of the signal converter 2 change due to environmental conditions such as ambient temperature and humidity or fluctuations in power supply voltage,
By performing the above calibration, the correction coefficients are corrected, and these influences can be avoided and thickness measurement with excellent accuracy and reproducibility can be performed.

The calibration operation of the ultrasonic thickness meter is performed as follows.

The calibration range ρ0 based on the dimensions of the test piece is 2o = KXt
o XC.

Ultrasonic propagation time in the TO2 calibration range, Co: reference sound velocity of the test piece, K indicates a correction coefficient.

K-2o, -'↑□xcm A correction coefficient is obtained from the above equation and held in the storage circuit 10.

When measuring the thickness of a material to be tested, when the sound velocity is known, the sound velocity setting device 11 is set to the sound velocity C of the material to be tested, and the ultrasonic probe 19 is brought into contact with the material to be tested via the couplant. Then, it can be automatically measured as thickness or p-knee. At this time, sound velocity calibration is not necessary.

If it is unclear whether the sound velocity is the same as the material to be tested, adjust the set values of the sound velocity setting device 11 and zero setting device 12 alternately using two types of test pieces 18 made of the same material as the material to be tested but with different measurement ranges. The sound speed from the sound speed setting device 11 is corrected in the second correction circuit 13 using the correction coefficient from the storage circuit 10 to obtain the actual sound speed, and then the sound speed is outputted as a signal via the first switching device 14 and the sound speed/zero signal generator 15. The ultrasonic thickness gauge is calibrated from the ultrasonic propagation time of the specimen material by the ultrasonic probe 19 by being applied to the transducer 2, and the thickness measurement fT with excellent accuracy and reproducibility is obtained.
I can do it.

In addition, in an ultrasonic thickness gauge equipped with multiple measurement ranges, if you memorize the above correction coefficient and the zero point calibrated using the test piece 18 for each measurement range in advance, you can calibrate it each time the measurement range is changed. There is no need to do this.

The sound speed display 17 displays the set value of the sound speed setting device 11 when the second switch 16 is set to the π measuring section, and displays the corrected actual sound speed when set to "sound speed".

When measuring the thickness of other test materials whose sound speed is known, the thickness can be quickly measured by simply setting the sound speed setting device 11 to a predetermined sound speed without performing sound speed calibration.

[Effects of the Invention] As explained above, the present invention is simple in that it includes an arithmetic circuit that obtains a correction coefficient from signals from a first reference device, a reference sound speed setting device, and a second reference device, and a correction circuit that corrects a sound speed setting value. With this configuration, once the sound speed of the material to be tested is set, the thickness can be automatically measured using the actual sound speed.

Calibration can improve accuracy and reproducibility by avoiding changes in characteristics due to environmental conditions such as temperature and humidity or fluctuations in power supply voltage.

When measuring thickness in multiple measurement ranges, if the correction coefficient and calibrated zero point for each measurement range are memorized, there is no need to perform calibration each time the measurement range is changed.

Calibrating the sound velocity and zero point using two types of test pieces with different measurement ranges has the effect of automatically obtaining the actual sound velocity.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing an embodiment of the first reference device, and Fig. 3 is an implementation of the second reference device. A block diagram showing an example, FIG. 4 is a block diagram of a conventional ultrasonic thickness gauge. In the figure, Y is the first reference device, 5 is the reference sound speed setting device, and 6 is the reference sound speed setting device.
is the reference zero setter, ヱ is the second reference device, 8 is the arithmetic circuit, 9
1 is a first correction circuit, 10 is a storage circuit, and 13 is a second correction circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. Patent applicant Tokyo Keiki Co., Ltd. Figure 1 5; Reference sound velocity setting device 6: Base! Door opening setting and repair 6; Arithmetic circuit 13 - second correction circuit

Claims (1)

[Scope of Claim] An ultrasonic thickness meter that injects ultrasonic waves into a material to be tested and measures the thickness of the material to be tested based on the ultrasonic propagation time within the material and a set speed of sound, which has different calibration ranges. a first reference device that individually generates a signal of the ultrasonic propagation time for the above, a reference sound speed setting device that sets the sound speed related to the above calibration, and a second reference device that individually generates a thickness signal corresponding to the above calibration range. and an arithmetic circuit that compares the thickness signal obtained from both the signals of the first reference device and the reference sound velocity setting device with the signal from the second reference device of the range and outputs a correction coefficient, and the arithmetic circuit output. An ultrasonic thickness gauge characterized by comprising a correction circuit that corrects the sound velocity set by.