JPH0493763A - Ultrasonic apparatus for flaw detection - Google Patents

Abstract

PURPOSE:To expand a range of detection of a defect and to improve the precision in detection by impressing a plurality of ultrasonic waves simultaneously on a body to be measured, from directions different from one another, and by causing interference intentionally among the ultrasonic waves. CONSTITUTION:Based on a pulse outputted from a transmission circuit 30, transmission vibrators 22a and 23a of each divided-type probe emit pulse-shaped ultrasonic waves simultaneously. Part of these ultrasonic waves is reflected on a fitting surface 4a and other enters a steel plate 4 and is propagated in the direction of focuses 25 and 26. Each reflected wave from a bottom surface or meeting with a defect in the course of propagation is made to enter a reception vibrator 22b or 23b and displayed 38 as a defect-reflected wave F, in addition to the transmission pulse wave, the surface-reflected wave and the bottom-reflected wave, through a reception circuit 31. Besides, phase-shift circuits 21a and 21b interposing between the circuit 30 and the vibrators 22a and 23a shift phases of the ultrasonic waves propagated through the steel plate from each other, so as to cause interference intentionally, and thereby increase the intensity of the ultrasonic wave at a remote distance from the fitting surface 4a, for instance. Accordingly, the characteristic of sensitivity of detection of the detect in the direction of the thickness of a body to be measured can be set in the most excellent state, and expansion of a range of detection of the defect and improvement of the precision in detection can be attained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an ultrasonic flaw detection device using a composite ultrasonic probe in which a plurality of probes are assembled into one container, and in particular, The present invention relates to an ultrasonic flaw detection device in which defect detection sensitivity characteristics in the thickness direction of a measuring object can be variably set.

C. Prior Art] Ultrasonic flaw detection devices have been put into practical use as one type of flaw detection device for detecting defects present in objects to be measured, such as steel plates. The ultrasonic flaw detection method is also specified in JIS (for example, JIS G-0801).

The ultrasonic probes used in this vertical ultrasonic flaw detection method can be roughly divided into two types: vertical probes and split-type probes, and each can be used depending on the thickness of the object to be measured and the purpose of use. ing.

FIG. 9(a) is a diagram showing a schematic configuration of a vertical probe.

This vertical probe 1 is disposed in a container 2 filled with a damper material or parallel to a mounting surface 4a of a single transducer 3 for transmitting and receiving ultrasonic waves or a steel plate 4 as an object to be measured. ing.

When a pulse signal is applied to the vibrator 3 from an external control device via the signal line 5, the vibrator 3 sends out ultrasonic waves 6 in the thickness direction (vertical direction) of the steel plate 4. The ultrasonic waves 6 propagated vertically within the steel plate 4 are reflected, for example, from the opposite surface (bottom surface) of the steel plate 4 and are incident on the same vibrator 3 . Therefore, the received signal a detected via the signal line 5 connected to the vibrator 3 includes the transmitted pulse wave T and the reflected wave B from the bottom surface, as shown on the right side of FIG. 9(a). included.

Here, if a defect exists inside the steel plate 4, the ultrasonic wave 6 is reflected by this defect, so there is no defect reflected wave caused by the defect between the transmitted pulse wave T and the bottom reflected wave B in the received signal a. arise. Therefore, the defect occurrence position (occurrence depth) and the defect scale indicated by the wave height (level) can be specified.

FIG. 9(b) is a diagram showing a schematic configuration of a split type probe. This split type probe 7 has a pair of vibrators 910 arranged at a slight angle with respect to the mounting surface 4a of the steel plate 4 in a container 8 filled with a wedge material and a damper material. The vertical position of the focal point 11 located on the perpendicular line can be adjusted by changing the inclination angle, changing the dimensions of the wedge material, etc.

When a pulse signal is applied from an external control device to one of the transducers 9 via the signal line 12a, the ultrasonic waves 6 are sent out from the transducer 9 in the direction of the focal point 11 within the steel plate 4. Further, the other transducer 10 receives ultrasonic waves input from the direction of the focal point 11, and sends the received signal to the control device via the signal line 12b. Therefore, as shown on the right side of FIG. 9(b), this received signal consists of a transmitted pulse wave T at the mounting position of the vibrator 10, a surface reflected wave S from all the mounting surfaces 4a, and a wave reflected from the bottom surface. The bottom reflected wave B is included.

Therefore, if a defect exists in the vicinity of the focal point 11 in the steel plate 4, the ultrasonic wave 6 will be reflected by this defect, so that the defect caused by the defect will occur between the surface reflected wave S and the bottom reflected wave B in the received signal. Reflected waves occur. Therefore, the location and size of the defect can be identified.

[Problems to be Solved by the Invention] However, even in the ultrasonic flaw detection apparatus using the vertical probe 1 or the split type probe 7 shown in FIG. 9, the following problems still remain to be solved.

That is, in the ultrasonic flaw detection apparatus using the vertical probe 1 shown in FIG. Since the pulse waves T are superimposed, even if a defect exists in that part, the reflected wave (echo) caused by the defect is buried in the transmitted pulse wave T, so there is a problem that it cannot be detected accurately.

Further, in the vertical probe 1, within a certain short-range sound field, the height of the detected defect reflected wave (defect echo) is not greatly influenced by the position where the defect exists (distance M from the mounting surface). However, beyond this near field limit distance,
The sound pressure of ultrasonic waves decreases due to diffusion phenomena and scattering phenomena due to crystal grain size. Therefore, the farther the defect position is from the mounting surface 4a, the lower the height of the defect reflected wave even if the defect is of the same size. Therefore, a problem arises in that the height of the defect reflected wave differs depending on the position where the defect is detected. As a result, it is not possible to make a pass/fail judgment for the object to be measured based on the height of the defect reflected wave. Therefore, it has been difficult to incorporate this ultrasonic flaw detection device into, for example, a product inspection line in a factory to automatically determine pass/fail of products.

On the other hand, in the split type probe 7 shown in FIG. 9(b),
Since the transmitted pulse wave T does not appear in the vicinity of the mounting surface 4a of the steel plate 4 in the received signal, it is possible to detect defects located deeper than the surface 1 to 21. However, the area where defects can be detected with high accuracy is as shown in Figure 10.
Only the shaded area (focal range) 13 centered on the focal point 11 is simultaneously covered by both the vibrators 9 and 10.

Therefore, the detection sensitivity of the reflected wave caused by the defect obtained in the received signal is as shown on the right side of the figure, in this region 13.
indicates the maximum value. Figure 11 shows each distance M in the thickness direction of the steel plate 4.
FIG. 3 is a defect detection sensitivity characteristic diagram showing the defect detection sensitivity at d. As shown, the distance fid beyond the area 13
Defect detection sensitivity decreases significantly in the region of . Further, the defect detection sensitivity also decreases at a position shallower than the region 13.

Therefore, similar to the above-described vertical probe 1, this split type probe 7 also has the problem that the quality of the product cannot be determined uniformly based on the height of the defect reflected wave.

In order to eliminate this inconvenience, a DAC (distance sensitivity correction) circuit is used to correct the defect reflected wave caused by a defect occurring at a long distance near the bottom surface to a size corresponding to the size of the defect in question. An ultrasonic flaw detection device has been developed.

By performing sensitivity correction using the DAC circuit in this manner, the operator can accurately grasp the scale of the defect regardless of the location of the defect by observing only the height of the output defect reflected wave. In addition, since it is possible to unconditionally detect defect reflected waves of a certain level or higher and output an alarm regardless of the location where they occur, there is no need for the operator to observe the defect waves and make judgments, and the defect detection speed can be increased. can be increased.

However, the operation of creating a correction curve (DAC curve) for the DAC circuit for performing this sensitivity correction is performed by the operator each time. To create this DAC curve, set the DAC starting point, DAC range, DAC mark, DAC slope value, etc.
Since the probe is not moved for each thickness of the steel plate 4 using the related adjustment knobs, it is necessary to adjust them to a constant level. This adjustment work was very complicated and required a high degree of skill, so it had to be carried out by a skilled person. Also, it was necessary to make adjustments every time a measurement was performed.

Furthermore, since the long-distance detection sensitivity is forcibly increased using, for example, an amplifier, noise caused by the amplification is likely to be mixed in, resulting in a problem in which the S/N ratio decreases. That is,
Essentially, the S/N in long-distance defect detection is significantly lower than the S/N in short-distance detection. Therefore, since it is only possible to obtain a uniform S/N characteristic over the entire measurement range in the thickness direction, there is a problem that the defect detection accuracy of the entire ultrasonic flaw detection apparatus using this split type probe is reduced.

The present invention was made in view of these circumstances, and
By simultaneously applying multiple ultrasonic waves to the object to be measured from different directions and shifting the phase difference of the ultrasonic waves, the ultrasonic waves are intentionally made to conflict with each other.
Complex adjustment work can be removed without the need for sensitivity correction using a C circuit, etc., and the defect detection sensitivity characteristics in the thickness direction of the object to be measured can be set to the best condition, thereby expanding the detection range and detecting defects. An object of the present invention is to provide an ultrasonic flaw detection device that can improve accuracy.

[Means for Solving the Problems] In order to solve the above problems, the ultrasonic flaw detection device of the present invention focuses a pair of transducers at different positions on a perpendicular line perpendicular to the mounting surface of the object to be measured. A composite ultrasonic probe consisting of multiple segmented probes arranged as shown in FIG.
A transmitting circuit that simultaneously applies pulse signals to a plurality of transducers incorporated in the composite ultrasound probe to generate pulsed ultrasonic waves, and at least one of the transmitting circuit and the plurality of transmitting transducers. A phase shift circuit is inserted between the two transducers to variably set the phase difference between the ultrasonic waves output from each transducer, and a phase shift circuit that receives the received signal output from each transducer. Due to defects included in the signal,
It is equipped with a receiving circuit that detects various reflected waves, and a display that displays each reflected wave detected by this receiving circuit.

Further, in another invention, the above composite ultrasonic probe includes:
A vertical probe with a transducer that transmits and receives ultrasonic waves in a direction perpendicular to the mounting surface of the measured object and a pair of transducers are arranged so as to focus on a perpendicular line perpendicular to the mounting surface of the measured object. It consists of a split type probe.

[Function] The ultrasonic flaw detection device configured in this manner is equipped with a plurality of split probes whose focal positions are set at different positions on a perpendicular line perpendicular to the mounting surface. and,
Pulse signals are simultaneously applied from the transmission circuit to each one of the transducers of each split type probe. Therefore, ultrasonic waves are simultaneously transmitted from each of these transducers to each focal direction. in this case,
Since the phase shift circuit is interposed between the transducer and the transmission circuit, the phase difference between the simultaneously output ultrasonic waves can be variably set by this phase shift circuit. That is, if the phases of the ultrasonic waves output from different directions are different, an interference phenomenon occurs between these ultrasonic waves at a position where some of these ultrasonic waves intersect. Due to this interference phenomenon, the ultrasonic waves mutually strengthen or weaken each other.

The phase difference between the ultrasonic waves at each intersection position changes depending on the position because their propagation paths are different. That is, the degree of interference changes depending on each position in the thickness direction (perpendicular direction) of the object to be measured.

The height (magnitude) of the reflected ultrasound wave caused by a defect corresponds to the intensity of the ultrasound at the location where the defect occurs, so if the phase difference between the ultrasound waves at the location where the defect occurs is zero, Since they strengthen each other, large defect reflected waves are detected. On the other hand, if the phase difference at the position where the defect occurs is 180°, they will weaken each other, so the detected defect reflected wave will be very small.

Since the phase difference at each position in the thickness direction of the object to be measured can be adjusted using a phase shift circuit, for example, the phase differences may weaken each other at a shallow (near distance M) position, and strengthen each other at a deep (long distance) position. They may be set so that they have a phase difference. With this setting, detection sensitivity at long distances can be increased. Note that since the detection sensitivity at short distances is originally much higher than that at long distances, it is not a big problem even if the detection sensitivity decreases to some extent due to interference.

Therefore, it is possible to obtain relatively uniform defect detection sensitivity characteristics over a short distance to a long distance.

Further, in another invention, the composite ultrasonic probe may be composed of the above-mentioned split type probe and the vertical probe, or even if such a composite ultrasonic probe is used, the Each ultrasound wave is transmitted in a different direction from a different location relative to the body. Therefore, by adjusting the phase difference between each ultrasonic wave using a phase shift circuit, it is possible to obtain relatively uniform defect detection sensitivity characteristics from a short distance to a long distance with the same effect as the invention described above. It becomes possible.

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

FIG. 1 is a schematic diagram showing an ultrasonic flaw detection device according to an embodiment.
FIG. 2 is a transparent perspective view showing a schematic configuration of a composite ultrasonic probe provided in this ultrasonic flaw detection apparatus.

This ultrasonic flaw detection device is broadly divided into a composite ultrasonic probe 20 incorporating a plurality of split type probes, and an ultrasonic probe 20 incorporating various circuits for operating this composite ultrasonic probe 2o. It is composed of a flaw detector 19 and phase shift circuits 21a and 21b.

In the composite ultrasonic probe 2o, a transmitting transducer 22a and a receiving transducer 22b are placed in a box-shaped container 2Oa.
a first split-type probe consisting of a transmitting transducer 23a;
and a second split type probe constituted by a receiving transducer 23b. Further, the container 2Oa is filled with a wedge material and a damper material. The transmitting transducer 22a and the receiving transducer 22b are disposed at symmetrical positions with the acoustic dividing plate 24 in between, and are inclined in a substantially V-shape. The mounting surface 4a of the focal point 25 of the first split type probe composed of the transmitting transducer 22a and the receiving transducer 22b
The distance M dp + in the thickness direction from M dp + is determined by the inclination angle.

Similarly, the transmitting transducer 23a and the receiving transducer 23b are disposed on the outside of the first split type probe with the acoustic dividing plate 24 in between, and are also inclined in a substantially V-shape. The distance dP2 in the thickness direction of the focal point 26 of the second split type probe composed of the transmitting transducer 23a and the receiving transducer 23b from the mounting surface 4a is determined by the inclination angle. In this embodiment, each vibrator 22a of the first split type probe.

By setting the inclination angle of 22b with respect to the mounting surface 4a to be larger than the inclination angle of the second split type probe, the focal position (distance d p+) is changed to the focal position (distance d F2) of the second split type probe. ) is located closer to the mounting surface 4a.

Further, each vibrator 22a is provided on the upper surface of the container 20a.

Four connection terminals 27 corresponding to 22b, 23a, 23b
a, 27b, 28a, and 28b are attached.

Each distance Md in the thickness direction of the first split type probe composed of the transmitting transducer 22a and the receiving transducer 22b
The detection sensitivity of the defect reflected wave caused by the above-mentioned defect in is the sensitivity characteristic A shown in FIG. 3(a). That is, the position of the focal point 25 (distance dF) has the maximum sensitivity, and the detection sensitivity decreases as the distance from the focal point position (distance Mdp+) increases. Similarly, the detection sensitivity of defective reflected waves in the second split type probe composed of the transmitting transducer 23a and the receiving transducer 23b has sensitivity characteristic B. In other words, the maximum sensitivity is at the position of the focal point 26 (distance Mdp2), and the focal position (distance dp2) is the maximum sensitivity.
The detection sensitivity decreases as the distance from F2) increases.

Note that in reality, the detection sensitivities of the split type probes do not completely match, but for example, each matching device such as a coil is connected to each connection terminal 27.
By inserting it between a to 28b and each vibrator 22a to 23b and changing the physical characteristics of each matching device,
As shown in FIG. 3(a), the maximum values of the sensitivity characteristics A and H of each split type probe are made to almost match.

The connection terminal 27a of the transmission transducer 22a of the first split type probe is connected to the transmission circuit 30 via the phase shift circuit 21b and the transmission terminal 29a of the ultrasonic flaw detector 19. Also,
Connection terminal 28 of the transmitting transducer 23a of the second split type probe
a is connected to the output terminal 29a via a phase shift circuit 21a. Furthermore, the first. The receiving transducers 22b and 23b of the second split type probe are commonly connected to the receiving circuit 31 via the receiving terminal 29b of the ultrasonic flaw detector 19.

The transmitting circuit 30 transmits a pulse signal C from the transmitting terminal 29a at regular intervals. The pulse signal C output from the transmission terminal 29a is directly applied to the transmission transducer 22a of the first split-type probe via the connection terminal 27B, and is applied to the second split-type probe via the phase shift circuit 21. Transmitting transducer 23a of the tentacle
is applied to

a transmission vibrator 22a to which a pulse signal C is applied;
Pulsed ultrasonic waves are transmitted from 23a to each focal point 25 and 26 at the same timing.

Since the phase shift circuits 21a and 21b are inserted in the path from the transmitting circuit 30 to the transmitting transducers 22a and 23a, there is a phase difference θ between the ultrasonic waves output from the transmitting transducers 22a and 23a. arise. The phase shift circuits 21a and 21b are composed of, for example, a delay circuit using a capacitor or the like, a coil such as a delay line, a monostable multivibrator formed of an IC, or the like. Note that since the phase shift circuits 21a and 21b are inserted in both paths, the direction in which the phase advances based on only the phase difference θ can be set arbitrarily.

In addition, each connection terminal 27 is connected to each receiving transducer 22b, 23b.
The reception signal e outputted through the terminals b and 28b is commonly input to the reception circuit 31 through the reception terminal 29b. The received signal e input to the receiving circuit 31 is amplified by a receiving amplifier 32, gain adjusted by a variable resistor 33, and further amplified again by an amplifier 34. Then, the high frequency noise component contained in the received signal e inputted by the wave detector 35 is removed. The received signal from which unnecessary components have been removed, which is output from the receiving circuit 31, is further converted by the waveform shaping circuit 36 into a simple peak wave signal that is easy for the observer to see, and then sent via the video amplifier 37 as a display. Applied to the vertical axis of the CR7 display 38.

Further, the time axis circuit 38 sends out a trigger signal to the time axis of the CR7 display device 38 in synchronization with the pulse signal C output from the transmitting circuit 30 at regular intervals. Therefore, C
The R7 display device 38 starts sweeping every time a trigger signal synchronized with the pulse signal C is input, so the display screen shows
As shown in the figure, the received signal e whose waveform has been arranged in each group Md is displayed with the horizontal axis (time axis) being the distance d from the mounting surface 4a of the object to be measured 4. This received signal includes a transmitted pulse wave T1, a surface reflected wave S, and a bottom reflected wave B, as in FIG. 9(b). If a defect exists in addition to these, the defect reflected wave F is also included.

Further, each electronic circuit component is supplied with a drive voltage V from the power supply circuit 40.
. is supplied.

In the ultrasonic flaw detection apparatus configured as described above, when the power is turned on, the pulse signal C is outputted from the transmission circuit 30 at regular intervals. As a result, each transmitting transducer 22a of the first and second split type probes.

23a are excited simultaneously, and each transmitting oscillator 22a.

Pulsed ultrasonic waves are output from 23a at the same timing. A part of the ultrasonic waves output from each transmitting transducer 22a, 23a is reflected by the mounting surface 4a, and the rest is reflected by the steel plate 4.
The light enters the center and propagates in 25° and 26 directions at each focal point. Then, the reflected waves reflected from the bottom surface of each receiving vibrator 22b, 2
3b. In addition, when a defect is encountered during propagation, the defect reflected wave reflected by the defect is transmitted to each receiving transducer 22.
b, enters 23b.

Therefore, each receiving transducer 22b of each split type probe.

The received signal e outputted from the receiving circuit 23b is displayed on the CRT display device 38 via the receiving circuit 31. As described above, in addition to the transmitted pulse wave T1, the surface reflected wave S, and the bottom reflected wave B, a defect reflection tiF caused by the defect is generated from the displayed received signal. Therefore, the presence or absence of defects and their scale can be determined.

Next, the effect of the phase shift circuits 21a and 21b will be explained using FIG. As mentioned above, this phase shift circuit 21g, 2
Yub is a transmission vibrator 23a.

By slightly changing the rise timing of each pulse signal applied to 22a, each transmitting transducer 22a, 23a of the composite ultrasonic probe 20 can be adjusted to the steel plate 4 as the object to be measured.
It has a function that can variably set the phase difference θ between the respective ultrasonic waves that are simultaneously output to the inside. In other words, if the phases of the ultrasound waves output from different directions are different, an interference phenomenon will occur between these ultrasound waves at the position where they intersect, and the intensity of the combined ultrasound wave at that position will be changes. As a result, the thickness direction of the object to be measured (
The intensity of the ultrasonic waves changes depending on each position in the perpendicular direction).

The phase difference at each position in the thickness direction (distance d from the mounting surface) of the object to be measured depends on the frequency of the ultrasonic wave and each transmitting transducer 22.
It changes depending on the phase difference θ at the time of output from a, 23a, the distance between each transmitting vibrator, the inclination angle with respect to the mounting surface 4a, etc. Therefore, phase shift circuits 21a, 21 .
By adjusting the initial phase difference θ at b, the phase difference at each position can be controlled.

As mentioned above, the height (magnitude) of the reflected ultrasonic wave caused by a defect corresponds to the intensity of the ultrasonic wave at the defect occurrence position, so by adjusting the phase difference θ with the phase shift circuit 21, The defect detection sensitivity characteristic in the distance d direction from the mounting surface 4a can be variably set.

FIG. 3(a) shows, as described above, that the first... FIG. 7 is a diagram showing defect detection sensitivity characteristics A and B at each distance d when each of the second split-type probes is used alone.

On the other hand, FIGS. 3(b) and 3(c) show the first
．． These are the defect detection sensitivity characteristics C and D of the defect reflected wave F detected in the received signal e when the second split type probes are operated simultaneously. In addition, each defect detection sensitivity characteristic C,
D is a phase shift circuit 21a.

21b shows a case where the phase difference θ between the ultrasonic waves output from each of the transmitting transducers 22a and 23a is set to different values.

As shown, in characteristic C of FIG. 3(b), it is possible to increase the detection sensitivity as the distance increases. Furthermore, in characteristic B of FIG. 3(c), the detection sensitivity at short distances is increased. In any case, the third
Compared to the case where each probe is used alone as shown in FIG.

4 to 7 show two types of split type probes P.

It is a figure which shows each defect detection sensitivity characteristic when the steel plate 4 is flaw-detected using Q. Phase shift circuit 21 used in this experiment
a and 21b are double-shielded coaxial cables for transmission timing delay, and each split type probe P,
The phase difference θ is variably set by adjusting the path length of each transmission pulse to the Q transmission vibrator. In the figure, PIO and QIO indicate a state in which a 10 m coaxial cable is inserted, P2O and Q20 indicate a state in which a 20 m coaxial cable is inserted, and further, P2O.

Q30 shows a state in which a 30m coaxial cable is inserted.

P and Q without numbers indicate a state in which no coaxial cable is inserted, that is, a reference state in which there is no phase difference θ between the two.

The characteristics of "P only" and "Q only" in Fig. 4 are detected when the split probes P and Q are not excited simultaneously, but are alternately excited individually without interfering with each other. This is a sensitivity characteristic. Moreover, rP+QJ is a detection sensitivity characteristic when simultaneous excitation is performed in a state where the phase difference θ is 0.

As is clear from this figure, if simultaneous excitation is simply performed, the detection sensitivity will decrease due to the interference phenomenon.

Figure 5 shows the detection sensitivity characteristics rP+Q10J when a 1.0 m coaxial cable is attached only to the split type probe Q, and the split type probe P is simultaneously excited while remaining in its reference state. A comparison is shown with the detection sensitivity characteristic rP10+QJ when a 10 m coaxial cable is attached only to the probe P and simultaneous excitation is performed with the split type probe Q in its reference state.

In this way, it can be understood that even if the phase difference θ is the same, the detection sensitivity characteristics differ depending on the direction of the phase difference θ.

Similarly, Fig. 6 shows a comparison between the detection sensitivity characteristic rP20+QJ and the detection sensitivity characteristic rP+Q20J, and Fig. 7 shows the comparison between the detection sensitivity characteristic rP30+QJ and the detection sensitivity characteristic r''P + Q.
A comparison with 3 Q J is shown.

In this way, by changing the length of the coaxial cable and appropriately setting the value and direction of the phase difference θ, it is possible to obtain the best defect detection sensitivity characteristics suitable for the purpose.

Therefore, unlike conventional equipment, there is no need to use a DAC circuit to correct the defect detection sensitivity characteristics, eliminating the need for complicated operations to adjust the DAC circuit, making it easy to use even if you are unfamiliar with this ultrasonic flaw detection equipment. Even if there is, flaw detection work can be carried out easily.

Further, as described above, since the phase shift circuit 21a521b can be realized with a simple circuit configuration, manufacturing costs can be significantly reduced compared to a conventional ultrasonic flaw detection device incorporating a DAC circuit.

Furthermore, as shown in Figure 3(b) and (c), since there is little decrease in defect detection sensitivity at long distances, it is necessary to electrically forcibly increase the detection sensitivity at long distances using an amplifier or the like. Therefore, the S/N ratio can be significantly improved compared to conventional devices.

In addition, it is possible to increase the defect detection sensitivity especially in the vicinity of the bottom surface far from the mounting surface 4a, so for example, it is not possible to disassemble and inspect the side opposite to the flaw detection surface of a product after assembly has been completed.
In cases where more rigorous inspection is required, it is also possible to specifically increase the defect detection sensitivity of only that part to accurately detect even small defects.

FIG. 8 is a schematic cross-sectional view showing a multi-Q IF' g-wave probe of an ultrasonic flaw detection apparatus according to another embodiment of the present invention. In addition, the ultrasonic flaw detector 19 and the phase shift circuit 2], a, 21b
Since this is the same as the embodiment shown in FIG. 1, the explanation will be omitted.

As shown in the figure, the composite ultrasonic probe 42 of this embodiment includes a transmitting transducer 41a that transmits ultrasonic waves perpendicularly to a steel plate 4 as an object to be measured, and a transmitting transducer 41a that transmits ultrasonic waves in a container 42a. A vertical probe consisting of a receiving transducer 4]b that receives data, and a split type probe consisting of a transmitting transducer 23a and a receiving transducer 23b arranged at an angle to each other with respect to the mounting surface 4a. It is stored. The split type probe then focuses 44 on the perpendicular line.

Even in the ultrasonic flaw detection apparatus configured in this way, the transmitting circuit 30 and each transmitting transducer 41a.

A pulse signal is simultaneously applied to 23a, and the phase shift circuit 2
1a and 21b each transmitting transducer 41a.

A phase difference θ can be generated between the ultrasonic waves output from 23a into the steel plate 4. Therefore, the degree of interference at each distance d is determined by the phase shift circuit 21a.

21b.

Therefore, almost the same effect as the embodiment shown in FIG. 1 can be obtained.

[Effects of the Invention] As explained above, according to the ultrasonic flaw detection device of the present invention,
By simultaneously applying multiple ultrasonic waves to the object to be measured from different directions and shifting the phases of the ultrasonic waves, interference is intentionally caused between the ultrasonic waves propagating within the object to be measured. For example, the intensity of ultrasonic waves at a long distance from the mounting surface is relatively increased compared to at a short distance. Therefore, it is not necessary to perform sensitivity correction using a DAC circuit, etc., and complex adjustment work can be eliminated, and the defect detection sensitivity characteristics in the thickness direction of the object to be measured can be set to the best condition, thereby expanding the defect detection range. It is possible to improve the detection accuracy.

[Brief explanation of the drawing]

1 to 7 show an ultrasonic flaw detection device according to an embodiment of the present invention, FIG. 1 is a schematic diagram showing the overall configuration of the device, and FIG. 2 is a composite ultrasonic probe. 3 to 7 are defect detection sensitivity characteristic diagrams, and FIG. 8 is a schematic diagram showing the schematic configuration of an ultrasonic flaw detection device according to another embodiment of the present invention. Fig. 9(a) is a schematic cross-sectional view showing a general split type probe, and Fig. 9(b) is a -
A schematic cross-sectional diagram showing a general vertical probe, Fig. 10 is a diagram for explaining the operation of a general split-type probe, and Fig. 11 is a defect detection sensitivity characteristic diagram of the split-type probe. It is. 4... Steel plate, 4a... Mounting surface,] 9... Ultrasonic flaw detector, 20.42-... Composite ultrasonic probe, 21a, 2
1b...Phase shift circuit, 22a, 23a, 41a...Transmission oscillator, 22b, 23b, 41b...Reception oscillator, 2
526.44... Focus, 30... Transmission circuit, 3]・
...Reception circuit, 38...CRT display device. Applicant's agent Patent attorney Takehiko Suzue District 4 dB Figure B dB 2a (a) (b) Figure Figure Figure

Claims (2)

[Claims] (1) A composite ultrasonic probe consisting of a plurality of split-type probes in which a pair of transducers are arranged to focus at different positions on a perpendicular line perpendicular to the mounting surface of the object to be measured; a transmitting circuit that simultaneously applies a pulse signal to a plurality of transducers incorporated in a composite ultrasonic probe to generate pulsed ultrasonic waves, and at least one of the transmitting circuit and the plurality of transmitting transducers; inserted between two vibrators,
A phase shift circuit that variably sets the phase difference between the ultrasonic waves output from each of the vibrators, and a phase shift circuit that receives the received signal output from each vibrator and detects various defects caused by defects contained in the received signal. An ultrasonic flaw detection device that includes a receiving circuit that detects reflected waves and a display that displays each reflected wave detected by the receiving circuit. (2) A vertical probe with a transducer that transmits and receives ultrasonic waves in a direction perpendicular to the mounting surface of the object to be measured, and a pair of transducers focused on a perpendicular line perpendicular to the mounting surface of the object to be measured. Pulse signals are simultaneously applied to a composite ultrasound probe consisting of a split-type probe and multiple transducers built into this composite ultrasound probe, each generating a pulsed ultrasound. a transmitting circuit interposed between the transmitting circuit and at least one of the plurality of transducers, the transmitting circuit variably setting the phase difference between the ultrasonic waves output from each of the transducers; A phase shift circuit, a receiving circuit that receives the received signal output from each vibrator and detects various reflected waves caused by defects contained in this received signal, and each reflected wave detected by this receiving circuit. An ultrasonic flaw detection device equipped with a display.