JPS5831868B2 - Automatic ultrasonic flaw detection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a plurality of (9) different probes in order to detect any defects in the weld, and simultaneously switches the signals from the four probes using a timer. This invention relates to an automatic ultrasonic flaw detection device that displays on a single CRT (cathode ray tube) and simultaneously performs flaw detection for a plurality of different purposes in one operation.

When detecting a defect in a welded part, if the defect is a crack or a line, it is appropriate to use an ultrasonic flaw detection method.

In defect detection using ultrasonic flaw detection, it has been found that defects that are perpendicular to the direction of travel of the ultrasonic beam are easier to detect.

Defects in the weld may be within the weld or between the weld and the base metal, but depending on the shape of the weld, the angle at which the ultrasonic beam is applied to the weld may be determined by the vertical or oblique method. In the bevel method, two angles that differ by more than 15° between 45° and 45° to 70° are necessary.
It is said that performing an ultrasonic flaw detection test at two angles is more effective in detecting all kinds of defects.

When done manually, it is easy to actually change the probe, but when automated, even changing the direction of flaw detection will result in a
(Fig. 9), it is necessary to store the device compactly.

There are already examples of operating as many as nine types of probes at the same time.
It is difficult to install a flaw detector and have nine ultrasonic operators perform flaw detection at the same time due to cost, manpower, etc., and in general, one (or several) flaw detectors change probes nine times (or several times). work is being carried out.

Detecting defects in welds and recording their positions and defect sizes is important for maintenance management of equipment under test (including welds), and is already being carried out in some cases.

Additionally, there are already devices that automatically shut down due to a defect signal.

The present invention detects any defects in the weld by switching the channels using a timer to simultaneously transmit and receive signals from nine probes, and excludes signals unique to the ultrasonic probe or signals emitted from the shape of the test object that are always present. , one C
By displaying signals from four probes simultaneously on the RT, the number of workers can be saved, nine different types of ultrasonic flaw detection can be performed with one operation, and the echo height and detection distance of defects can be adjusted. It is an object of the present invention to provide an apparatus capable of performing an automatic ultrasonic flaw detection test that detects flaws corresponding to the flaw detection position, issues an alarm at the flaw position, and automatically stops the operation.

That is, the present invention works in conjunction with an ultrasonic flaw detector, a probe drive device, and an ultrasonic flaw detector that simultaneously display on a CRT having nine different types of probes, channel switching type, and two gates, and detects the reflected echo height and flaw detection. This system is characterized by the ability to automatically perform ultrasonic flaw detection in one operation using a recording device that simultaneously records distance and probe position, and nine different types of probes.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1A shows an example in which defective holes of the same size but different depths are provided in the material 3. Generally speaking, due to the characteristics of the ultrasonic probe (hereinafter referred to as F probe) 7, it is possible to So A, B
, C are as shown in the opening of Figure 1.

This means that even for defects of the same size, if the detection distance (distance from the probe to the defect) is different, the height of the received signal (echo height) will be different.

As shown in Figure 1, it is difficult to judge the size of the defect based on the echo height alone, so a distance amplitude calibration curve (DAC) is used.
Curve) 15(1) is required.

Using this DAC curve, it is possible to determine the shape (size) of defects at different locations of flaw detection distances.

If this DAC curve can be made electrically horizontal, the size of the defect can be determined only from the echo height and voltage, regardless of the detection distance, as shown in DAC curve 15 (5).

Conventional ultrasonic flaw detectors can correct carbon steel materials by about 40 decibels (100 times), but they can be used for materials with large attenuation, such as mainly austenitic stainless steel materials and their welded parts. In some cases, only a few decibels (approximately twice as much) of correction can be made.

FIG. 2 shows an example in which signals from four probes 7 are displayed on one CRTl, and FIG. 2B shows an example in which four DAC curves 15 are displayed based on signals from four probes 7.

When the four probes 7 are moved simultaneously and displayed on the CRTl, four transmitted waves 14 and reflected (defect) echoes 16 appear as if hanging over the mouth.

4 DAC curves 15 (1). (2) , (3
), (4) In some cases, it is generally not possible to visually distinguish between the four types of DAC curves 15 and the four types of reflected echoes 16 on the CRTl.

Therefore, we measured the 4 packets of DAC curves in advance 15 (1)
, (2), (3).

Among (4), select the echo height with the lowest echo height and create an AC curve 15 as shown in the opening of Figure 2 as the severe side.

If you visually observe the CRTl using this D'AC curve 15 as a reference, it is A if no echo height higher than this curve appears on the CRTl.

It can be said that there are no defects larger than the standard formulas B and C.

FIG. 3 shows an example where a reflected (defective) echo 16 appears on the CRTl.

The gate 18 is used to detect the height H (generally 0 to 11 cm) of the reflected echo 16 above the threshold level 17 within the gate (between the width G) as a signal to the outside.

In some cases, the time T until the reflected echo within the gate can be taken out directly to the outside as a DC voltage.

FIG. 3A shows a case where a reflected echo 16(1) with a threshold level of 17 or higher appears in the gate, and the reflected echo height H(1) and time axis T(1) can be extracted as signals to the outside.

The opening in Figure 3 is a case where reflected echoes 16 (1) and (2) with a threshold level of 17 or higher appear in two places within the gate 18, and the external signals include reflected echoes 16 (1) and (2) with a threshold level of 17 or higher. 2), the echo height H(
2) appears, and the time axis is T(
1) appears, so if there are two or more reflected echoes 16, the echo heights H1, 2' of the reflected echoes may not correspond to the external signals on the time axes T1, 2.

Therefore, in such cases, use a video tape recorder to record the CR.
The reflected echo on Tl must be recorded or the reflected echo on CRT1 must be visually observed.

In this case, when four probes are displayed on the CRTl at the same time, it is necessary to stop the operation and check which probe is emitting a large signal (whether the height of the reflected echo is high).

Fig. 4 shows a system for simultaneously moving four different types of probes.The probe 7 is switched by a timer 2 via a distance amplitude calibration device 6, a transmitting/receiving device 5, and is displayed on a CRTl, and a transition is sent to a recorder 8. The maximum echo height within the gate 18 can be recorded through the gate 4, and a signal higher than the threshold level 17 is transmitted to the control device 9.The signal from the gate 4 is transmitted to the control device 9 as a stop signal to activate the probe driving device 10 of the probe 7. The recorders 8 that have received signals from each of the four probes 7 are stopped.
The diagram on the recording paper is for each probe (c
Since the time axis and echo height are recorded simultaneously for h1 to h4) (each pen does not intersect), which probe 7 has an echo height of threshold level 17 or higher?
The reflected echoes of channels 1 to 4) were immediately determined from the recording paper, and the probe driving device 10 was stopped, and the reflected echo height of threshold level 17 or higher found on the recording paper was detected from the CRTl, and the CRTl was photographed. Record by video tape recorder, copying, etc.

It is also easy to correspond to each channel on the recording paper by moving the indicated amount of reflected echoes from each probe for 4 channels at the same time.

FIG. 5 shows an example of recording with the recorder 8, in which the time axis and echo height on the CRTl are converted into DC voltages and are input to the recorder 8 and recorded on the recording paper 21 as output signals of the ultrasonic flaw detector.

If the pens of the recorder 8 cross each other, the relationship between the time axis and the echo height will be slightly different, so they do not cross each other and move at the same position (simultaneously) with respect to paper feed.

The paper feeding speed is a multiple of 360 m1n per rotation (360°) for the rotation of the probe 1 (when detecting flaws from the inside or outside of the pipe) to facilitate analysis after recording.
, 72, 90, 180, 360 determine the relationship between the pulse signal from the probe drive device and the pulse motor of the recorder 8, and for axial movement, the probe 7
The recording paper is 0.5, 1.2, 5.1 for each movement distance of
It has a recording speed that can be set to move 0rn11L.

2 or 20 pen recorders with 10 pens
By using one pen-type device, ultrasonic flaw detection tests using nine different types of probes can be recorded on recording paper in one operation.

FIG. 6 shows an example in which a two-part bevel probe 22 is brought into contact with a base material 12. An electric signal transmitted through a probe cable 23 is guided to a diaphragm 20, and the voltage is converted into an ultrasonic signal by the diaphragm 20. A portion of the sound wave 19 travels in the direction of the arrow on the surface of the base material 12 and is transmitted into the base material 12, and a reflected portion is transmitted to the absorption plate 24.

This absorption plate 24 needs to completely absorb the ultrasonic wave 19, but the reflected waves that cannot be absorbed by the absorption plate 24 return to the original path and reach the diaphragm 20 to some extent (the diaphragm 20 (converted to voltage) may appear as a reflected echo 16 as shown in FIG.

(Echoes that always appear may also appear depending on the shape of the test object.

) Since this reflected echo 16 always appears at the same distance (the distance between the diaphragm 20 and the absorption plate 24 is constant), it can be distinguished from the reflected echo from a defect by visually observing the CRT1 (the distance between the diaphragm 20 and the absorption plate 24 is constant). Since it is difficult to see on the recording paper 21 (if the time axis of the reflected echo moves), two gates 18 are set, 01 and G2, and the reflected echo unique to the probe, which always appears, is excluded and recorded.

This constantly reflected echo generally appears in the near field of the probe 7, so if the base material 12 is thick or
Even if the wall thickness of the echo 16 is thin, if a distant defect is to be searched for, the gate 18 can be set to the rear G2 of the echo 16 that is constantly reflected, as shown in Fig. 7, so that even a single gate method can be used. You can use it.

In ultrasonic flaw detection testing, applying ultrasonic waves directly to defects is good for defect analysis, and the reflected ultrasonic waves are reflected and refracted, resulting in the spread of the ultrasonic beam and the partially delayed echoes of the ultrasonic waves. Analysis becomes difficult due to mode conversion of vertical and transverse waves due to appearance, shape, etc.

When inspecting a thin base metal 12 or a welded part of the base metal directly (without reflection), it is necessary to remove the reflected echo 16 that is constantly reflected by the probe 7, as shown in FIG.

This constantly appearing reflected echo is almost reduced by adopting the two-segment probe 22.The two-segment probe 22 is a side view of the probe 7 seen from the side in FIG. 8A, and the mouth is a plan view of the probe 7 seen from above. It is.

If there are two diaphragms 20 as shown in Figure 8, the ultrasonic waves 19 will not return the way they came because they are at a certain angle to each other, so almost no reflected echo will appear in the probe 7. .

FIG. 9 shows an example of the arrangement of the probe 7 for performing an ultrasonic flaw detection test on a circumferential welded portion of a pipe from the outside.

Here, there are 7(1) and 7(2) as vertical probes, and 2
In the case of a split type, two types of diaphragms 20 with different angles of 90° are installed at symmetrical positions on the piping, and for angle flaw detection, a 45° bevel probe pointing to the right and left in the circumferential direction is used. 7
(3), 7(4), 7 with 60' bevel probe
(5) ? (6), axial layer, left (or top, bottom: 7 (7), ?( with 45° oblique probe as orientation)
8), 7 with a 60° bevel probe (9), 7
(10), 7(8), 7(4) to the 4-channel ultrasonic flaw detector 25(1) in FIG.

7 (5), ? (9) to 25(2) to 7(7)
, ? (3), 7(6), 7(10), and the signal from 7(2) is connected to the one-channel flaw detector 26 so that the respective signals do not interfere.

Of course, since the signals to the four probes in the 4-channel flaw detector 25(1) are switched between 100 and 500 Hz by a timer, no interference occurs between the probes connected to the 4-channel flaw detector 25(1).

Although an example of flaw detection from the outside is shown here, flaw detection from the inside can be considered in the same way.

FIG. 10 shows an overall system that takes into account the contents of FIGS. 1 through 9 described above.

Probe 7 (1) in contact with welding part (including base metal) 13
The probe driving device 10 that operates the probes 7 (10) is controlled by a signal from the control device 9, and the probe 7 is connected to the control device 9.
The positions (1) to 700) receiving pulse signals from the reed switch 11 of the probe driving device 10 are digitally displayed.

Is ultrasonic flaw detector 25 (1) a probe? (8), 7(
4) Receiving the signals of 7(5) and 7(9), the recorder 8 records the reflected echo height and the flaw detection distance, and the recorder receives the probe position signal from the probe driving device 10 with a signal from the control device 9. 8 is probe 7(1) to 7(
10) It moves in synchronization with the pulse signal of the reed switch 11 indicating the position.

The two 4-channel flaw detectors 25(1) and 25(2) and one of the 1-channel flaw detectors 26 are connected to the probes 7(1) to 25(2).
By combining 7(10) in this way, flaw detection is possible with 9 probes 7(
2) to 700) Ultrasonic flaw detection can be performed at the same time without interference of each probe.

Next, the effects of the above device will be described.

To use ultrasonic testing for welding defect detection,
In order to detect various defects, it is necessary to use several different types of probes (sensors) together.

When testing signals from different probes using one flaw detector, the test must be performed as many times as the number of probes (9 times), which takes time.

In particular, when working inside a nuclear power plant where workers are exposed to radiation, it is important to shorten the time and minimize the radiation exposure of workers.

Here, in order to perform flaw detection efficiently using nine types of professional nibs with different flaw detection directions or angles, we combined two 4-channel flaw detectors that simultaneously transmit and receive signals from each probe and one single-channel flaw detector to perform the entire flaw detection process. By using three probes, it is possible to detect all defects in one flaw detection operation by transmitting and receiving signals from nine types of probes at the same time, and four channels are simultaneously displayed on one CRT (switched by a timer, visually checked). By displaying the flaw detection results for four channels on a CRT (simultaneous display above), one worker can easily see the flaw detection results on the CRT.Fault echo heights and flaw detection distances for the four channels are recorded during flaw detection, and each gate is Each channel has two echoes, and it is possible to exclude and record echoes unique to the probe and echoes that are not due to welding defects due to the shape of the test object.

If a reflected echo above the threshold level appears, the probe automatically stops, immediately records the defect location, defect shape, and detection distance, and re-investigates (detailed investigation).

The recording feed speed is 360 in the circumferential direction; and in the axial direction, it can be recorded with a 10 (20) pen recorder that operates on a scale of multiples of 1, and it is possible to simultaneously investigate each defect position and shape on the recording paper. The pens are designed so that they do not cross each other.

If signals are sent to and received from nine probes at the same time, the ultrasonic beams of each probe will interfere with each other or receive signals from other probes, making flaw detection impossible.

Therefore, out of the 9 probes, the bevel probes were divided into 4 probes, and the 4 probes were switched instantaneously using a timer to prevent interference with the flaw detection between each probe, and the 4 probes were switched to transmit and receive ultrasonic waves. Therefore, it is desirable to use it at a flaw detection distance of 200 m111 or less.

Vertical probes are also used for coupling checks to ensure that there is sufficient flow of water or other liquid as a couplant to transmit ultrasound between the probe and the test object.

As explained above, according to the present invention, nine different types of ultrasonic flaw detection probes can be operated simultaneously, and the probes are designed to prevent the probes from interfering with each other or picking up signals from other probes. Due to the arrangement and ultrasonic transmission/reception method (timer switching, etc.), nine types of ultrasonic flaw detection can be performed simultaneously, and the flaw detection time can be reduced to one-ninth.

Generally, one ultrasonic flaw detector requires one ultrasonic flaw detector operator to visually inspect the cathode ray tube (CRT) of the flaw detector, but by displaying signals from different probes simultaneously, The channel (for 4 people) allows flaw detection to be carried out visually by one operator, and a recorder synchronized with the flaw detection position records and displays the defect echo height and flaw detection distance at the same time.The 2-gate system also allows detection of defects other than defects. The vertical probe serves as a coupling check, and the second gate allows automatic stopping if the coupling is bad.

By combining the various functions described above, automation becomes possible for the first time as a rational system for ultrasonic flaw detection testing that has multiple types of probes.

[Brief explanation of the drawing]

Figure 1 A is a diagram showing the shapes of defects with the same dimensions and shape but different distances to the defect. A diagram showing the distance amplitude curve (DAC curve) of each probe using the signals from the four probes. Figure 3 shows the relationship between the reflected echo from the defect and the gate. In Figure 3 A, there is an example of one reflected echo, and in Figure 3, two reflected echoes appear on one gate. Figure 4 is a diagram showing an example of switching each channel of a 4-channel ultrasonic flaw detector using a timer, Figure 5 is a diagram showing an example of recording, and Figure 6 is a diagram showing an example of recording. Figure 7 is a diagram showing the principle behind the generation of reflected echoes from inside the probe, which is unique to the middle probe. Figure 7 shows an example of displaying reflected echoes from inside the probe on a CRT. Figure 8A shows the cross section of the beveled two-piece probe. diagram showing,
Figure 8 is a view from above of the beveled two-piece probe of A, Figure 9
The figure shows an example of probe arrangement as an example of ultrasonic flaw detection testing of pipe welds from the outside. Figure 10 shows an example of a system that combines two 4-channel ultrasonic flaw detectors and one 1-channel flaw detector. FIG. 1...CRT (cathode ray tube), 2...
Timer 4...Transition gate, 5...
・Pulsar receiver (transmission/reception device), 6... Distance amplitude calibration device, 7... Probe (search unit)
, 8...Recorder, 9...Control device,
10... Probe drive device, 20...
Vibration plate, 22...2-split bevel probe, 24.
...Absorption plate, 25 ... Ultrasonic flaw detector (4
channel type), 26... Ultrasonic flaw detector (1 channel type).

Claims (1)

[Claims] 1. A plurality of ultrasonic flaw detection probes attached to the test tube, a drive mechanism that drives these probes along the test tube, and ultrasonic signals obtained from these probes. In an automatic ultrasonic flaw detection device that includes an ultrasonic flaw detector that amplifies the signal and a display that displays the signal amplified by the ultrasonic flaw detector, the probes are attached in a circular shape to the test tube to be protected, and these The ultrasonic emission direction of the probe is set to the direction of the plane containing this ring, the axis of the protected first circular tube, and the probe, and the ultrasonic emission direction is set to the direction of the plane containing the ring. Selecting a plurality of probes facing around the circumference and one probe each facing upward and downward in the direction of the plane containing the axis of the protected tube and the probes as a first group; A plurality of probes whose ultrasonic emission directions are set around the difference in direction of the plane containing the annular ring, and one probe each whose ultrasonic emission direction is set upward and downward in the direction of the plane containing the axis of the test tube and the probes. An automatic ultrasonic flaw detection apparatus characterized in that the probes in the same group are selected as a second group, and the probes in the same group are sequentially emitted and received at predetermined time intervals.