JP3006232B2 - Ultrasonic testing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector used for detecting defects in a test object such as the inside of a steel material or a welded portion of a steel material and measuring the sound speed and ultrasonic attenuation of the test object. It is.

[0002]

2. Description of the Related Art A method of detecting the presence of a defect by making an ultrasonic pulse incident on a test body and detecting an ultrasonic pulse reflected by a defect in the test body is well known.
The ultrasonic test equipment is used to realize the above method, and FIG. 5 shows a configuration example. In the figure, 1 is an oscillator, 2 is a transmitter that generates an electric pulse 2a by using an output 1a of the oscillator 1 as a trigger, 3 is an ultrasonic probe that generates ultrasonic waves based on the electric pulse 2a from the transmitter 2, 4 is a receiver for amplifying a signal from the ultrasonic probe 3 and 5 is a receiver 4
6 is a time axis generator for generating a sawtooth wave 6a for generating a time axis on the display 5 by using the output 1a of the oscillator 1 as a trigger, and B is a display from the bottom. A reflected wave, F is a reflected wave from a defect, S is a test specimen, and d is a defect.

Next, the operation will be described with reference to FIGS. 6 and 7. 6A shows the output waveform of the oscillator 1, FIG. 6B shows the output waveform of the transmitter 2, and FIG. 6C shows the waveform detected by the output of the receiver 4. (D) is an output waveform of the time axis generator. FIG. 7 is an ultrasonic flaw detection pattern displayed on the display 5, where T indicates a transmission pulse, and B ₁ and B ₂ indicate bottom echoes.

The output 2a of the transmitter 2 is input to the ultrasonic probe 3 in synchronization with the rise of the output 1a of the oscillator 1, and the ultrasonic probe 3 converts the output 2a of the transmitter 2 into an electroacoustic signal. An ultrasonic pulse is generated and made incident on the specimen S. The ultrasonic pulse propagates through the inside of the test sample S, and if there is an acoustic discontinuity such as a defect d in the middle, the ultrasonic pulse is reflected and reflected as a reflected wave F by the ultrasonic probe 3.
Return to Further, the ultrasonic pulse reaching the bottom surface of the test sample S returns to the ultrasonic probe 3 as a reflected wave B. Reflected waves F and B
Is converted into an electric signal by the ultrasonic probe 3 and then amplified and detected by the receiver 4 to become an output 4a. Outputs 4a and 1a
Is input to the display 5 such as a cathode ray tube for observation, and the ultrasonic inspection figure shown in FIG. 7 can be observed.

[0005]

The ultrasonic flaw detection test apparatus using a cathode ray tube as a display is required to have easy-to-read or good visibility of the ultrasonic flaw detection pattern shown in FIG. 7 as one of particularly important performances. You. One of the measures is to improve the brightness of the ultrasonic flaw detection figure. As a means for improving the brightness, a method of increasing the voltage applied to the rear-stage acceleration electrode of the CRT or a method of increasing the number of generations of the electric pulse shown in the output 2a per unit time, that is, increasing the repetition frequency PRF of transmission is used. is there. The method of increasing the applied voltage is limited by the maximum rated value determined by the structure of the cathode ray tube. on the other hand,
In the method of increasing the PRF, a residual phenomenon described below may occur.

FIG. 8 is a diagram for explaining the residual phenomenon.
8A shows an output waveform of the receiver 4 and FIG. 8B shows an ultrasonic flaw detection pattern. The transmission repetition period T _PRF defined in the figure is preferably shorter in order to brighten the ultrasonic flaw detection figure of FIG. 8B. However, depending on the structure, shape and size of the specimen S, the attenuation amount of the incident ultrasonic pulse is small, and the specimen S reciprocates many times in the specimen to cause multiple reflection. FIG.
The example of (a) illustrates this situation, in which the time during which multiple reflections continue is longer than the transmission repetition period T _PRF . FIG.
The echo g shown in the ultrasonic flaw detection pattern in (b) is a part of the multiple reflection, but is displayed on the left side of the _first bottom echo B1, and thus is erroneously recognized as the defect echo F. The above is the residual phenomenon and its adverse effects. Conventionally, in order to avoid the residual phenomenon, the repetition frequency PRF of the transmission has to be reduced and the brightness of the ultrasonic inspection figure has to be sacrificed.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems. An ultrasonic flaw detection apparatus which can easily determine whether an echo is due to a residual phenomenon by looking at an ultrasonic flaw detection pattern displayed on a display device. A test apparatus is provided.

[0008]

SUMMARY OF THE INVENTION An ultrasonic flaw detection test apparatus according to the present invention devises a repetition period T _PRF of a transmission and a time axis, and does not set the period T _PRF to a fixed time. Cycle T out of N transmissions out of M transmissions
_{The PRF} is changed by the time Δt.

[0009]

According to the present invention, the repetition period T of the transmission and the time axis is used.
The existence of the residual echo is confirmed on the display by changing the _PRF by the time Δt.

[0010]

【Example】

Embodiment 1 FIG. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 7 is a delay circuit, 8 is an N / M frequency divider (M and N are integers of 1 or more and M> N), and 9 is a Δt switch.

Next, the operation will be described with reference to FIGS. 2 is an output waveform diagram of each part shown in FIG. 1. FIG. 2 (a) shows the output 1a of the oscillator 1, FIG. 2 (b) shows the output 7a of the delay circuit 7, and FIG. 2 (c) shows the frequency divider. 8 at the output 8a of M =
2, N = 1, FIG. 2D shows the output 9 of the Δt switch 9
2A shows the output 2a of the transmitter 2, and FIG. 2F shows the output 6a of the time base generator 6. Note that the output 4a of the receiver 4 has a multiple reflection waveform shown in FIG.

The rising time of the output 7a of the delay circuit 7 is delayed by Δt from the rising time of the output 1a of the oscillator 1. The Δt switch 9 receives the output 1 a of the oscillator 1, that is, the signal of Δt ≒ 0 and the two signals of the output 7 a of the delay circuit. The frequency divider 8 receives the output 1a of the oscillator as an input, and
The divided output 8a is output. The output 8a is input to the Δt switch 9 as a switch signal of the Δt switch. The .DELTA.t switch 9 operates so as to output the output 1a of the oscillator when the output 8a of the frequency divider is at the H level and to output the output 7a of the delay circuit when the output 8a is at the L level. Therefore, the delay time Δt from the output terminal of the Δt switch with respect to the rising time of the oscillator output 1a is Δ
Outputs 9a of two types of rising waveforms having t ≒ 0 and Δt = Δt shift appear alternately.

The output 9a of the Δt switch 9 is input to the transmitter 2 and the time axis generator 6. As a result, the output 2 of the transmitter 2
a and the output 6 a of the time axis generator 6 are the output 9 of the Δt switch.
It is output in synchronization with the rise time of a. FIG. 3 is an ultrasonic inspection pattern displayed on the display unit 5 of the ultrasonic inspection apparatus having the components shown in FIG. 1. The transmission pulse T and the bottom echoes B ₁ and B ₂ are observed as stationary signals. However, the echo g displayed on the right side of the transmission pulse T due to the residual phenomenon can be observed in a state where the echo g is shifted left and right by the time Δt. This makes the echo g "a residual echo"
Can be determined.

Embodiment 2 FIG. When the time Δt is set to a constant value in the first embodiment, the following problem occurs. In the ultrasonic test pattern shown in FIG. 3, the length of the time axis is a constant value determined by the screen size of the display 5, but the time T _S is used by changing according to the size (thickness) of the specimen S. It is common to do. Therefore, the value calculated by Equation 1 is 4, 5
%, The echo g remains stationary on the display 5.
There is a case where the amount of blur is large enough to be seen in a book and cannot be determined as “residual echo”.

ΔT / T _S × 100 Equation 1

In the second embodiment of the present invention, the time Δt is set to the time T _S
The above problem can be solved by changing the value calculated according to the expression 1 within a range (reference range) of, for example, 2 or 3%. This will be described below with reference to the drawings. FIG. 4 is a view showing a second embodiment of the present invention, and each part is the same as in FIG.
However, the time T _S signal from the time axis generator 6
Is different. The delay circuit 7 operates to change Δt of the output 7a according to the time T _S. That is, the delay circuit 7 operates so as to change Δt so that the value calculated by the equation 1 falls within the reference range when the time T _S increases.

In the second embodiment, the time Δt is set to the time T _S
Although the output of the time axis generator 6 is introduced into the delay circuit 7 in order to change it in accordance with the above, the Δt of the delay circuit 7 may be manually switched according to the thickness of the test sample S. .

[0018]

As described above, according to the present invention, the oscillation
Delay circuit that outputs the output signal of the
N / M (M and N are integers) dividing the output of the oscillator
M> N) divider, output of the oscillator and delay circuit
Output is switched by the output of the frequency divider, and the switched
Switching the output to the input side of the time axis generator and transmitter
Display device, the residual phenomenon on the display
Can be determined whether the echo.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an ultrasonic flaw detection test apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing waveforms at various points in FIG. 1;

FIG. 3 is a diagram showing a flaw detection figure appearing on a display of the device according to the present invention.

FIG. 4 is a configuration diagram of an ultrasonic flaw detection test apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a configuration diagram of a conventional ultrasonic test equipment.

FIG. 6 is a diagram showing waveforms at various points in FIG. 5;

FIG. 7 is a diagram illustrating a flaw detection figure for explanation of a conventional technique.

FIG. 8 is an explanatory view of a conventional technique for explaining a residual phenomenon.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2 Transmitter 3 Ultrasonic probe 4 Receiver 5 Display 6 Time axis generator 7 Delay circuit 8 Divider 9 Δt switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-25548 (JP, A) JP-A-58-129358 (JP, A) JP-A-62-175661 (JP, A) Jikken Sho 53- 27027 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (2)

(57) [Claims] An oscillator for generating a predetermined repetition frequency, a delay circuit for delaying the output signal of the oscillator by a time Δt and outputting the same, and an N / M for dividing the output of the oscillator
(M and N are integers>M> N) A frequency divider, a switch for switching the output of the oscillator and the output of the delay circuit by the output of the frequency divider, and a corresponding output switched by the switch. a transmitter that generates a transmission signal, an ultrasonic probe that converts an output of the transmitter into an ultrasonic wave and makes it incident on a test body , and converts a reflected wave from the test body into an electric signal; A receiver for amplifying an electric signal from the ultrasonic probe, a display for displaying an output of the receiver, and a switch for switching by the switch.
And a time axis generator for generating a time axis on the display by the output . 2. A ultrasonic testing apparatus according to claim 1, wherein which is adapted to vary in response to the thickness of the time Δt of the delay circuit specimen.