JPS5965252A - Ultrasonic automatic flaw detecting apparatus - Google Patents

Abstract

PURPOSE:To prevent the generation of a region not subjected to flaw detection by a simple control treatment without enhancing the accumulation density of a probe array, by successively sending out ultrasonic beams different in refractive angles every time when the probe array is changed over to oscillate the same. CONSTITUTION:A focus delay part 14 has eight delay elements each having a delay amount shown in the size in a longitudinal direction and ultrasonic beams from the probe groups of a probe array 10 are converged in the vicinity of the center O of a tubular body 12 to be inspected. On the other hand, in an argument delay part 16, ultrasonic beams converged in the vicinity of the center O of the tubular body are converged to the focus F1 on an X-axis coming to an eccentric amount d1 by the delay elements increased in the delay amounts thereof. Eight probe groups of the probe array 10 are used as one group and the argument delay parts 16A, 16B,... successively reduced in the delay amounts are successively changed over to perform oscillation for sending out ultrasonic beams B, B2,... of which refractive angles theta1, theta2,... are successively changed. By this method, the generation of a region not subjected to flaw detection is prevented by a simple control treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a stationary method in which a probe array in which a plurality of probes are arranged in a ring is fixedly installed in water, and defects in an object to be inspected are detected by switching and scanning the probe array. This article relates to automatic ultrasonic flaw detection equipment.

In order to enable automatic ultrasonic flaw detection over the entire circumference of steel pipes, etc., without mechanically rotating the probes, the inventors of the present application developed an underwater probe play system in which multiple probes are arranged in a ring. A predetermined number of probes are fixedly installed in a group and sequentially switched and scanned in a fixed direction, and the ultrasonic beam characteristics equivalent to those of a focusing probe are obtained in the transmission pulse for the selected probe group by switching scanning. A device that detects defects from the combined received signal by applying the same delay to the received signal from each probe as at the time of transmission so as to eliminate the difference in reception timing due to differences in propagation distance. is proposed.

However, in the switching scan of the probe array in the above device, for example, as shown in FIG. 1, the beam B1 having the refraction angle θ is After performing flaw detection, shift the probe one position to the left and set /162 to /16.
By selecting probe group No. 9, flaw detection is performed using beam B having the same refraction angle θ, but an undetected area A is created between beams B and B2 where the beam is not irradiated.

In this case, it is conceivable to narrow the pinch in mounting the probes in the probe array 10, but if the pinch is narrowed, the number of probes will increase significantly and the switching scanning circuit will become considerably complicated.
Probe play is also expensive in terms of cost.

The present invention has been made in view of the above, and an object of the present invention is to prevent the occurrence of undetected areas through cylindrical control processing without increasing the degree of integration of probe plays.

In order to achieve this objective, the present invention transmits 11i-order ultrasonic beams with different refraction angles by switching the transmission/reception delay amount in multiple stages each time the probe array is switched and scanned, thereby narrowing the beam. It was designed to make it swing.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 2 is an explanatory diagram showing a probe array used in the present invention, and FIG. 3 is a sectional view taken in the 110 direction.

In Fig. 2.3, 10 is a probe array, which is formed by arranging a plurality of probes in a ring, and this probe array 10 is fixedly installed in water 11, and the probe Child array 10
As shown in the figure, a tube body 12 as an object to be inspected is transported in the axial direction.

The ultrasonic beam switching scan by the probe array 10 is performed by, for example, forming one group of eight probes with a predetermined position of the probe array 10 as a reference position, and a group of probes forming an l group. By delaying the supply of the transmission pulse signal to the focal point probe, a wholesale acoustic beam characteristic equivalent to that of a focusing probe is created, and the switching scan of the probe array is performed in clockwise or counterclockwise directions in units of one group. A switching scan is performed in which the probe is sequentially shifted by the length of the probe.

4, 5 and 6 are explanatory diagrams showing the swinging effect of the ultrasonic beam due to the probe play of the present invention.

First, the ultrasonic beam characteristics of the probe array 10 shown in FIG. 4 are those obtained by delay control such that the focal point F1 is located on the There is.

That is, the probe array 1008 forming one group
By supplying ultrasonic pulse signals to the probe groups through the focus delay section 14 and the declination delay section 16A, the eccentricity d1 from the center 0 of the tube body 12 is shown by the broken line.
It is possible to create a characteristic that focuses the ultrasonic beam on the focal point F on the X axis.

Here, in the focal beam characteristics shown in FIG. 4, between the angle of incidence 11 on the tube 12 and the angle of refraction θ1, the longitudinal sound velocity of water CW is 1500 m/s, and the shear sound velocity of steel Cs-; 32
30 m/s, the following relationship holds true.

On the other hand, since 5inil is given by 1sini,=...(2), substituting this equation (2) into the equation (1) above, d.

JF2.16-...The relationship (3) is obtained.

That is, if the focal point F1 of the ultrasonic beam is set on the X-axis where the displacement amount d1 is, the incident angle 11 is determined from the outer diameter 2r of the tubular body 12 according to the above equation (2), and the above-mentioned @(
3) From the formula, the refraction angle θ with respect to the tube body 12! Setting the ultrasonic beam characteristics equivalent to such a focus probe, which has a uniquely defined orientation, is achieved by adjusting the amount of delay for each probe in the focus delay section 14 and the deflection angle delay section 16. can do.

That is, the focus delay unit 14 is equipped with a delay element for each of the eight probes, and the delay amount increases sequentially from both sides toward the center, as shown by the longitudinal size of the delay element. By setting this delay amount, an ultrasonic beam characteristic is created to focus the ultrasonic beam from the probe group of the probe array 1o near the center O of the tube body 12, and the ultrasonic beam is suspended.

On the other hand, the declination delay unit 16A is also provided with a delay element for each probe, and the amount of delay is gradually increased from the left side to the right side, as shown by the lengthwise size of the delay element.
By setting this delay amount, a deflection angle characteristic is created in which the ultrasonic beam, which is focused near the center 0 of the tubular body 12 due to the delay of the focus delay unit 14, is focused to the focal point F8 on the X-axis having the eccentricity dI.

5 and 6 also have a focus delay section 14 and an argument delay section 16B, 16C as in FIG. 4, and the focus delay section 14 has a fourth
The delay amount is set the same as in the figure, but the argument delay section 1
For 6B and 16C, different delay amounts are set for the argument delay section 16A.

In other words, the argument delay section 16B of FIG. 5 is set so that the amount of delay increase of the delay element, which increases stepwise from the left side to the right side, is smaller than the argument delay section 16A of FIG. 4. Therefore, the focal point F2 of the ultrasonic beam from the probe group is located at a position of eccentricity ft d t from the center O of the tube body 12, and this eccentricity d is set to be smaller than the eccentricity d in Fig. 4. The amount of delay of the argument delay section 16B is determined as follows.

Therefore, since dz<d+, the above (2) (3)
As is clear from the formula, the incident angle i and the refraction angle θ are also the fourth
It will be smaller than the figure.

Furthermore, FIG. 6 shows the amount of gradual increase from the left side to the right side of the delay element in the argument delay unit 16C in the argument delay unit 1 of FIG.
6B, the eccentricity d3 of the focal point F3 of the ultrasonic beam of the probe array 10 is the eccentricity d in FIG.
, becomes smaller, and similarly the incident angle i3 and the refraction angle θ8
also becomes the minimum according to the amount of eccentricity d8.

That is, in the present invention, when eight probe groups in a probe array of 1° are selected as one group, the declination delay units 16A, 16B, and 16C are used for the focus delay unit 14.
By sequentially switching and connecting the ultrasonic pulse signals, the refraction angle becomes θ.

, θ2. Ultrasonic beam B1 that changes sequentially with θ3. B.

This oscillates the ultrasonic beam that sends out Bs.

Incidentally, although the swing control shown in Figs. 4 to 6 takes the transmission of ultrasonic beams as an example, the same delay applies to received signals of echoes reflected from defects caused by ultrasonic beams B1 to B. Through control, the deflection angle and focus are delayed so that received signals having different propagation times are received at the same timing for each probe.

FIG. 7 is a block diagram showing one embodiment of the present invention.

First, to explain the configuration, 18 is a control signal generator Tearly;
Based on the program control of the microcomputer 44, a switching signal for swinging the 48 sound wave beams, a switching signal for switching and scanning the probe array 10, a control signal for reception timing, etc. are output.

Reference numeral 14 denotes a focus delay unit. The same delay amount as the focus delay unit 14 shown in FIGS. 4 to 6 is set for each probe, and the transmission control signal from the control signal generator 18 is pulsed. Since it is a signal, the signal is delayed in the same way as when an analog delay element is used by outputting a clock pulse from a counter synchronized with the transmission control pulse.

Reference numeral 20 denotes a changeover switch, which sequentially switches and connects the changeover terminals 20a, 20b, and zoc every time eight probe groups in the probe array 1° are selected as one group. 16A, 16B, and j6C are argument delay units, and
The delay 1tT#fi4 is set to be the same as that of the declination delay unit shown in Figures 6 to 6, and since the signal input via the changeover switch 2° is a pulse signal, the delay is determined by the counting of the counter in the same way as the focus delay unit 14. A predetermined amount of deviation angle is created.

In addition, the declination angle i)' (deflection delay of the extending portions 16A to 16C (, Q
are set to different values as shown in FIGS. 4 to 6. The refraction angle of the ultrasonic beam by the declination delay unit 16A is θ1, and the refraction angle by the declination delay unit 16B is θ7. , furthermore, the amount of argument delay is set so that the refraction angle by the argument delay unit 16C is θ.022 is a transmitting unit, and transmits a transmission control signal sequentially output from the argument delay units 16A to 16C. The ultrasonic oscillator is then driven, and a transmission pulse signal with a certain delay is output for each probe. Reference numeral 24 is an analog switch, which sets the reference position of the probe array 1o to the star i position and sets a group of 8 probes as one group, and rotates P'J' + constant rotation for one probe at a fixed period. Switch and scan in the direction.

Further, the probe groups of the probe array 10 selectively connected by the analog switch 24 are connected to the receiving side declination delay units 26A and 26T3.
, 26CK are also connected.

The declination η extension parts 26A to 26C are set with the same declination delay 5: as the declination delay parts 16A to 16C on the receiving side, so that the received signal from the probe array 1o is analog No. 48. For some reason, the same analog delay element as shown in the argument delay section of FIGS. 4 to 6 is used.

28 is a changeover switch, Luci, reception side changeover switch 20
The switching terminals 28a to 28c are sequentially switched and connected in synchronization with .

30 is a preamplifier, and 32 is a focus delay unit, which is set with the same delay amount as the focus delay unit 14 on the transmitting side, and similarly delays analog signals, so it is analog A delay element is used.
- 34 is an adder that adds and synthesizes the received signals of each probe that are input in parallel from the focus delay unit 32; 36 is a distance that corrects changes in signal level with respect to the ultrasonic propagation distance for the combined signal of the adder 34; Since it performs amplitude correction and uses the microcomputer 44 as a processing means for the received signal, it is an A/D that converts the synthesized altruistic signal into a digital signal.
It has a converter. The digital reception signal of the main multiplier 36 is sent to the buffer 38. * to the mixing-level comparator 4o. The mixing level comparator 4o determines that the digital received signal from the main amplifier 36 is a defective received signal when it exceeds the reference level, and removes the signal that is below the reference level as a noise component and generates an ultrasonic wave by the transmitted pulse signal. A received component due to direct beam recirculation is removed by a control signal generator 18 based on a transmission control signal.

Further, the mixing level comparator 42 receives a distance signal a, a flaw detection mode signal and a defect position signal C via buffers 42, 44 and 46.

Here, the distance signal a uses a pulse signal from a pulse generator driven by a heron sent to the probe array 1o, and detects the longitudinal position of the tubular body with respect to the reference position. That's what I do.

Also, the flaw detection mode signal is θ due to the swing delay.

, θ2. A signal for identifying any one of .theta.3 is input and used to instruct reception processing such as defect position.

Furthermore, the defect position (9 (a) is the switching position of the probe array 1o based on the switching control signal of the analog switch 24,
That is, in order to identify which probe has received the defect signal, it is given as an angle signal with respect to the reference position of the probe array 1°.

The output of the mixing level comparator 4o is inputted to a microcomputer 44 via an input interface 42, which processes defects and defect positions based on the input data.
Printer 48 .via output interface 46 . CRT
I try to hit it at 50 and record it.

Next, the operation of the embodiment shown in FIG. 7 will be explained with reference to the operational flow shown in FIG.

When a tube containing a subject is introduced into the probe array 10 fixedly installed in the water, the control signal generator 18 switches the analog switch 24 to generate a scanning signal under the control of the microcomputer 44. output and probe array 1
A group of eight probes having a reference position of 0 as a starting position are selectively connected to the transmitting section 22 and the declination delay sections 26A to 26C on the receiving side.

Subsequently, the control signal generator 18 outputs a transmission control signal and a switching signal for transmitting the ultrasonic beam having the refraction angle θ1. This switching signal causes the changeover switches 20 and 28 to
is switched to the switching contacts 20a and 28a as shown in the figure, and then the transmission control signal whose focus is delayed in the focus delay unit 14 according to the transmission control signal is input to the declination delay unit 16A via the changeover switch 20, and F, After being subjected to a constant declination delay, the ultrasonic beam is supplied to the transmitter 22, which drives the ultrasonic beam provided for each probe group, and the probe array lO selected via the analog switch 24. A transmission pulse signal is supplied to the probe group.

Therefore, from the probe group of the probe array 10, an ultrasonic beam equivalent to a focal probe with a refraction angle θ shown in FIG. Reflected signals due to defects such as scratches and cracks are received by the same probe group and input to the receiving-side declination delay circuit 26A. The received signal subjected to the declination delay in the declination delay circuit 26A is preamplified by the preamplifier 30 via the changeover switch 28 which is switched to the changeover contact 28a, and the focus delay in the focus delay section 32 causes the reception signal to be preamplified by the preamplifier 30. The signals are combined in an adder 34 and converted into a digital signal after distance and amplitude correction in the main amplification section 36, which is input to the mixing-level comparator 40 via a buffer 38a.

At the same time, distance signals a,
Flaw detection mode (U signal and defect position signal C are also input, and a received signal exceeding the reference level is compared and determined as a defect signal in the mixing-level comparator 40, based on distance signal a indicating the defect position and defect position signal C. The data are input to the microcomputer 44 through the input interface x42'i.

Subsequently, when the defect detection based on the refraction angle θ is completed, the changeover switch 20.28 switches to the switching contacts 20b and 28b, and the refraction angle θ! is changed by transmitting and receiving similar ultrasonic waves. Defect detection is performed using an ultrasonic beam (see Fig. 5).

Furthermore, the changeover switch 20.28 has a changeover contact 10C.

28C, and defect detection based on the refraction angle θ3 is performed by transmitting and receiving similar ultrasonic waves.

The reception signal obtained by the microcomputer 44 by the beam swing by switching the ultrasonic beam at the refraction angle θ, ~θ, is determined by a predetermined program calculation to determine whether or not there is a defect. Data indicating the size and defect position is ejected and recorded on the printer 48°cn, T5o via the output chinon face 46.

Claims (1)

[Claims] A probe play in which a plurality of probes are arranged in a ring is fixedly installed in the water, and a predetermined number of probes in the probe array are set as one group and sequentially switched and scanned in the circumferential direction of the axis, and for each switching scan. In an automatic ultrasonic flaw detection device that detects defects in a tubular metal passing through a probe play with ultrasonic beam characteristics equivalent to those of a focused probe by transmitting and receiving delays of a group of seven selected probes, the probe An ultrasonic automatic apparatus characterized in that nine beam oscillation means are provided for oscillating the ultrasonic beam by multi-stage switching of the transmission/reception unit for the probe group each time the probe group of the array is switched and scanned. Flaw detection equipment.