JPS6053805A - Ultrasonic wave thickness gage - Google Patents

Abstract

PURPOSE:To make it possible to measure thickness accurately, by adding a circuit, which automatically judges the ordinal number of an echo at a bottom surface immediately after a transmitted wave in the sequence of echoes. CONSTITUTION:The output of a pulsor 4 is converted into a sound wave by a transmitting and receiving device 2 and transmitted to a material to be checked 1. The sound wave reflected by the bottom surface of the material to be checked 1 is received by the transmitting and receiving device 2. The received signal is sent to time measuring ciruits 6 and 7 through an amplifier 5. A time tn from a point of the transmitted wave T to an echo Bn immediately after the T at the bottom surface is measured by the circuit 6. At the same time, a time tn+1 from the point of the transmitted wave T to the next echo Bn+1 at the bottom surface is measured by the circuit 7. By an operating circuit 8, n=tn/(tn+1-tn) is computed. A thickness Tx is computed by using Tx=vt1/(2n), where (v) is a sound speed in the material to be checked 1. Thus the thickness Tx is accurately measured.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a thickness needle using ultrasound.

[Background of the invention]

In Fig. 1, 1 is the material to be tested, 2 is the transceiver, 3 is the signal processing device, %TX is the thickness of the material to be tested, T is the transmitted wave, B is the first bottom surface,
B2 shows the second bottom echo.

A transmission wave T is transmitted from the surface of the test material 1 by the transmitter/receiver 1, is reflected at the bottom surface of the test material 1, becomes a first bottom echo B, and is received by the transmitter/receiver 2.

Thereafter, the transmitted wave T repeats multiple reflections and is received as a second bottom echo Bl% third bottom echo Bs1...

Conventionally, when measuring the thickness Tx of a material to be inspected, the time t'' from when the transmitted wave T is transmitted to when the first bottom echo B is received is measured, and then It is converted into the wall thickness Tx of the material to be inspected according to equation (1).

Here, V is the sound velocity in the test material l.

Furthermore, when the thickness Tx of the material to be inspected is small, as shown in FIG. 3, the first bottom echo B1 enters the transmitted wave T, making it impossible to measure the b1 time t1. Therefore, the time "zk" until the second bottom echo B immediately after the transmitted wave is measured and converted to the thickness Tx of the material to be inspected according to the following equation (2).

Similarly, when the bottom echo immediately after the transmitted wave T becomes the n-th bottom echo, the relationship between the time t and the wall thickness Tx is as follows.

Here is n digit positive integer.

The wall thickness Tx determines the echo number of the bottom echo immediately after the transmitted wave T, so conventionally, if the approximate value of the wall thickness Tx of the material to be tested is known in advance, the measurement range can be changed using a changeover switch. ? By switching, equation (3
) was set.

Therefore, if the approximate value of the wall thickness Tx of the material to be inspected is not known in advance, accurate measurement may not be possible.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thickness needle that allows accurate measurement even when the approximate value of the wall thickness TI of a material to be inspected is not known in advance.

[Embodiments of the invention]

All specific examples thereof will be explained below.

4 in FIG. 4 is a pulser, which is connected to the transmitter/receiver 2, and the output of the pulser 4 is converted into a sound wave by the transmitter/receiver 2 and transmitted to the material 1 to be inspected. The sound waves reflected from the bottom surface of the test material 1 return to the surface and are received by the transceiver 2, and this received signal is sent to the time measurement circuits 6 and 7 via the amplifier 5.

The time measurement circuit 6 measures the time t, 1 from the transmission wave T to the bottom echo 81 immediately after the transmission wave T, and at the same time, the time measurement circuit 7 measures the bottom echo Bn+, t received next from the transmission wave T to the bottom echo 81 immediately after the transmission wave T. Measure the time 1s+ at . t
, and '++-1-1 according to equation (4), equation (3)
It is calculated by the n'l calculation circuit 8.

By using the above n(!:tsi), the wall thickness Ty is calculated in the arithmetic circuit 8 according to equation (3).

In this way, even if the wall thickness Tx is unknown, equation (3)
n can be determined and accurate measurements can be made.

〔Effect of the invention〕

According to the present invention, accurate measurement is possible even when the approximate value of the wall thickness Tx of the material to be inspected is not known in advance.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are explanatory diagrams of the conventional measurement method, and Figure 4
The figure is a block diagram of the measuring device of the present invention. DESCRIPTION OF SYMBOLS 1... Test material, 2... Transmitter/receiver, 3... Signal processing circuit, 4... Pulser, 5... Amplification circuit, 6.7.
...Time measurement circuit. Agent Patent Attorney Akio Takahashi (5) 9

Claims (1)

[Claims] 1. A device for measuring the wall thickness of a material to be inspected using ultrasonic waves, which is equipped with a circuit that automatically determines whether the bottom echo immediately after the transmitted wave is the second echo. An ultrasonic thickness needle characterized by: