JPH04212055A - Compound supersonic probe - Google Patents

Abstract

PURPOSE:To enable a defect to be detected with an approximately uniform sensitivity over a wide distance range in thickness direction by incorporating a plurality of division-type probes, having different focusing positions on a perpendicular to the surface for mounting a body to be measured, in one container. CONSTITUTION:Transmission vibrators 12a and 13a and reception vibrators 12b and 13b are placed at symmetrical positions sandwiching an acoustic division plate 14 within a box-type container 11 while being slanted nearly in chevron shape. Then, by setting a slant angle of a steel plate to be measured 4 of the vibrators 12a and 12b constituting a first division-type probe for a mounting surface 4a of the steel plate to be measured 4 to a value which is larger than an inclination angle of the vibrators 13a and 13b constituting a second division-type probe, thus enabling a focusing position 15 to be located closer to a mounting surface 4a than a focusing position 16. Therefore, by adjusting the inclination angle and enabling the focusing positions 15 and 16 of each probe to be distributed from a shallow position to a deep position near a bottom surface in perpendicular direction for the mounting surface 4a, a defect can be detected highly accurately with nearly a uniform sensitivity over a wide distance range including a short distance and a far distance in thickness direction within a steel plate 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite ultrasonic probe in which a plurality of split type probes having different focal positions are assembled into a single container.

0002

2. Description of the Related Art Ultrasonic flaw detection has been put into practical use as one of the flaw detection techniques for detecting defects present in objects to be measured, such as steel plates. The method is also specified in JIS (for example, JIS G-0801).

[0003] 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 type is used depending on the thickness of the object to be measured and the purpose of use. It is being

In the vertical probe, a vibrator is arranged parallel to the surface of the object to be measured, and a pulse signal is applied to this vibrator to send pulsed ultrasonic waves to the object to be measured. The voltage is applied perpendicular to the surface. Then, this ultrasonic wave propagates vertically within the body to be measured and is reflected at the bottom surface. The same transducer then receives the reflected wave. If a defect exists in the propagation path of the ultrasonic wave, the ultrasonic wave is reflected by the defect, so that the received signal extracted from the vibrator includes a reflected wave caused by the defect. Therefore, the location where the defect occurs and its scale can be grasped.

However, in this vertical probe, the transmitted pulse waveform is superimposed on a very shallow part near the surface of the object to be measured, so even if a defect exists in that part, the reflected wave due to the defect will not be reflected. (Echo) is buried in the transmitted pulse wave, so there is a problem that it cannot be detected accurately. For example, when using a 5 MHz vibrator, the range where the defect cannot be measured is 10 mm from the mounting surface of the vertical probe.
It may even reach. According to the above-mentioned JIS, the thickness t of a steel plate that can be measured using this vertical probe is 13 m.
m or more. In order to eliminate such inconveniences, it is necessary to use a split type probe.

FIG. 8 is a schematic diagram of a split type probe. In this split type probe 1, an ultrasonic transmitting transducer 3a and a receiving transducer 3b are arranged at a slight angle with respect to the mounting surface 4a of a steel plate 4 in a container 2 filled with a wedge material and a damper material. has been done. The vertical position of the focal point 5 located on the perpendicular line can be adjusted by changing the inclination angle. When a pulse signal is applied to the transmitting transducer 3a from an external control device via the signal line 6a, the ultrasonic wave 7 is transmitted from the transmitting transducer 3a in the direction of the focal point 5 within the steel plate 4. Further, the receiving transducer 3b receives the ultrasonic waves input from the direction of the focal point 5, and sends the received signal a to the control device via the signal line 6b. Therefore, as shown on the right side of FIG. 8, this received signal a includes a transmitted pulse wave T at the mounting position of the receiving transducer 3b, a surface reflected wave S at the mounting surface 4a, and a reflected wave B at the bottom surface. is included.

[0007] Therefore, if a defect exists in the vicinity of the focal point 5 in the steel plate 4, the ultrasonic wave 7 is reflected by this defect, so that the surface reflected wave S and the bottom reflected wave B in the received signal a are
A defective wave is generated due to the defect. Therefore, the location and size of the defect can be identified.

According to such a split type probe 1, since the transmitted pulse wave T does not appear near the mounting surface 4a (surface) of the steel plate 4 in the received signal a, the transmission pulse wave T does not appear in the vicinity of the mounting surface 4a (surface) of the steel plate 4 in the received signal a. It is possible to detect certain defects. That is, compared to the above-mentioned vertical probe, it has the advantage of being able to more reliably detect defects existing near the surface.

[0009]

However, the split type probe 1 shown in FIG. 8 still has the following problems to be solved.

That is, the area where defects can be detected with high accuracy using the receiving transducer 3b is the focal point 5, as shown in FIG.
Only the shaded area (focal range) 8 is simultaneously covered by both of the vibrators 3a and 3b centered on . Therefore, the detection sensitivity of a defective wave caused by a defect obtained in the received signal a has a maximum value in this region 8, as shown on the right side of the figure. FIG. 10 is a detection sensitivity characteristic diagram showing the defect detection sensitivity at each distance d in the thickness direction of the steel plate 4. As shown in the figure, the defect detection sensitivity is significantly reduced in a region at a distance d beyond the region 8.

[0011] Therefore, this split type probe 1 has a problem that thick steel plate 4 cannot be measured. J mentioned above
IS also stipulates that the thickness t of the steel plate 4 that can be measured using this split type probe 1 is less than 20 mm.

Moreover, since the defect detection sensitivity varies greatly depending on the distance d as shown in FIG.
, it is specified that a DAC (distance sensitivity correction) circuit is used to correct a defect wave caused by a defect occurring at a long distance near the bottom surface to a size corresponding to the size of the defect.

[0013] By performing sensitivity correction using the DAC circuit in this way, the operator can accurately grasp the scale of the defect by observing only the height (level) of the output defective wave, regardless of the location where it occurs. . Moreover, since it is sufficient to output an alarm upon detecting a defect wave of a certain level or higher, the flaw detection speed can be increased.

However, the DAC for performing this sensitivity correction
The work of creating a curve is performed by the operator each time. To create this DAC curve, adjust the DAC-related adjustment knobs such as the DAC starting point, DAC range, DAC mark, and DAC slope value to a constant level while moving the probe for each thickness t of the steel plate 4. Need to adjust. Since this adjustment work is very complicated, it is necessary to carry out this work by a skilled person. Further, it was necessary to perform adjustments every time a measurement was performed.

Furthermore, since the long-distance detection sensitivity is forcibly increased using, for example, an amplifier, there is a problem in that noise due to amplification is likely to be mixed in, resulting in a reduction in S/N. That is, essentially the S/N in long-distance defect detection
is significantly lower than the S/N at short distances. Therefore, it is not possible to obtain uniform S/N characteristics over the entire measurement range in the thickness direction, resulting in a problem that the defect detection accuracy of the entire ultrasonic flaw detection apparatus using this split type probe is reduced.

The present invention has been made in view of the above circumstances, and by incorporating a plurality of split type probes with different focal positions into the same container, it is possible to measure near and far distances in the thickness direction of the object to be measured. We provide a composite ultrasonic probe that can detect defects with almost uniform detection sensitivity over a wide distance range, expanding the defect detection range, improving detection accuracy, and improving flaw detection work efficiency. The purpose is to

[0017]

[Means for Solving the Problems] In order to solve the above problems, in the composite ultrasonic probe of the present invention, the ultrasonic transmitting transducer and the receiving transducer are arranged perpendicularly to the mounting surface of the object to be measured. A plurality of split-type probes arranged to focus on different positions on a perpendicular line are assembled in the same container. Further, in another invention, the number of split type probes incorporated into the same container is two.

In still another invention, a split type probe focuses the vibration frequency of each vibrator of the split type probe at a position close to the mounting surface of the object to be measured at a position far from the mounting surface. The vibration frequency is set higher than the vibration frequency of each vibrator.

[0019]

[Operation] According to the composite ultrasonic probe configured in this way, the focal points of each split type probe incorporated in the container are set at different positions on the perpendicular line perpendicular to the mounting surface. . As mentioned above, the defect detection sensitivity of the split type probe is best within a certain range centered on the focal position. Therefore, by mutually adjusting the focal positions of each split type probe and dispersing the focal positions from a shallow position near the surface in the perpendicular direction to a deep position near the bottom surface, the location of the defect, if any, can be determined. The defect can be detected with high accuracy using a segmented probe with the best detection range. That is, the location and size of defects can be measured with high precision over a wide range in the perpendicular direction. Furthermore, in another invention, the number of split type probes incorporated in the same container is set to two, thereby obtaining the maximum effect with a small size, light weight, and low manufacturing cost.

Furthermore, the vibration frequency of each vibrator of the split type probe that focuses at a position close to the mounting surface of the object to be measured is changed from the vibration frequency of each vibrator of the split type probe that focuses at a position far from the mounting surface. It is set higher than the vibration frequency of the vibrator. in particular,
If the vibrators are made of the same material, decreasing the thickness of the vibrator will increase the vibration frequency, and increasing the thickness will decrease the vibration frequency.

Generally, the higher the frequency of the ultrasonic waves incident on the object to be measured, the more minute defects can be detected, but the more easily the ultrasonic waves are attenuated. Conversely, the lower the frequency of ultrasonic waves, the harder it is to attenuate, but the harder it is to detect minute defects.

On the other hand, when the object to be measured is, for example, a steel plate, fine defects harmful to material mechanics are likely to occur near the surface, and conversely, at deep internal positions from the surface of the steel plate,
Since concentrated stress is relatively less likely to occur, micro defects are less likely to occur.

[0023] Therefore, fine surface defects harmful to material mechanics can be detected with high precision at a high frequency using a split type probe having a focal point at a relatively short distance from the mounting surface. on the other hand,
By using a segmented probe that focuses at a deep position in the object to be measured, relatively large defects deep in the object to be measured can be reliably detected at a low frequency. That is, it is possible to reliably detect flaws from minute defects near the surface of the object to be measured to large defects at deep positions in a single operation.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the schematic structure of a composite ultrasonic probe according to an embodiment, and FIG. 2 shows a state in which this composite ultrasonic probe is attached to a steel plate as an object to be measured. It is a cross-sectional schematic diagram.

In this composite ultrasonic probe 10, a transmitting transducer 12a and a receiving transducer 12b constituting a first segmented probe and a second segmented probe are housed in a box-shaped container 11. A transmitting transducer 13a and a receiving transducer 1 forming a tentacle
3b is incorporated. In this embodiment, each of the vibrators 12a to 13b is made of the same material and has the same thickness. Therefore, since they have the same resonant frequency, when a pulse signal is applied, they vibrate at the same frequency.

Further, the container 11 is filled with a wedge material and a damper material. Then, the transmitting vibrator 12
a, the receiving transducers 12b are arranged at symmetrical positions with the acoustic dividing plate 14 in between and inclined in a substantially V-shape. The distance dF1 in the thickness direction of the focal point 15 of the first split type probe composed of the transmitting transducer 12a and the receiving transducer 12b from the mounting surface 4a is determined by the above-mentioned inclination angle.

Similarly, the transmitting transducer 13a and the receiving transducer 1
3b is disposed on the outside of the first split-type probe with the acoustic dividing plate 14 in between, and is also inclined in a substantially V-shape. The transmitting transducer 13a and the receiving transducer 13
The distance dF2 in the thickness direction of the focal point 16 of the second split type probe constituted by b from the mounting surface 4a is determined by the above-mentioned inclination angle. In this embodiment, the focal position ( The distance dF1) is located closer to the mounting surface 4a than the focal position (distance dF2) of the second split type probe.

Furthermore, four connection terminals 17a, 17b, 18a, 18b are attached to the top surface 11a of the container 11, corresponding to each vibrator 12a, 12b, 13a, 13b. Then, each connection terminal 17a to 18b and each vibrator 12
a to 13b are connected via a matching box 19 made of, for example, a coil for each gain adjustment. Each connection terminal 17a
~18b are connected to the control device 20.

[0030] Then, the transmitting transducer 12a and the receiving transducer 1
The detection sensitivity of the defect wave caused by the above-mentioned defect at each distance d in the thickness direction of the first split type probe composed of 2b and 2b is a sensitivity characteristic A shown on the right side of FIG. Therefore, the position of the focal point 15 (distance dF1) has the maximum sensitivity. Therefore, the amount of attenuation of detection sensitivity is -3, for example, from the maximum sensitivity.
The flaw detection area AR, which can accurately detect defects up to dB, spreads vertically around the focal point (distance dF1).

Similarly, the transmitting transducer 13a and the receiving transducer 1
The detection sensitivity of the second split type probe composed of 3b and 3b is sensitivity characteristic B. Therefore, the flaw detection area BR where the position of the focal point 16 (distance dF2) has the maximum sensitivity and can detect defects with high accuracy is the flaw detection area AR of the first segmented probe.
Some of them overlap. Conversely, each flaw detection area AR, BR
The respective focal positions dF1 and dF2 are set so that there are mutually overlapping portions in the .

[0032] Therefore, defects occurring in a short distance section from the surface (mounting surface 4a) of the steel plate 4 to the distance dC where both sensitivity characteristics A and B intersect are detected by the first split type probe,
Furthermore, defects occurring in a long distance section from distance dC to distance t (thickness of the steel plate) may be detected using the second split type probe. Specifically, the split type probe that is the transmission source of the received signal used for defect detection analysis is switched according to the distance d.

Although the detection sensitivities of the split type probes do not completely match, by changing the physical characteristics such as the resistance of each matching device 19 made of a coil, as shown in FIG. The maximum values of the sensitivity characteristics A and B of each split type probe are made almost the same.

Therefore, the location and size of defects at each distance d from the mounting surface 4a to the opposite surface (bottom surface) of the steel plate 4 as the object to be measured can be accurately detected with substantially the same detection sensitivity.

[0035] Furthermore, since the same detection sensitivity can be obtained over a wide distance range, there is no need to perform sensitivity correction using a DAC circuit, unlike the conventional method using only one split type probe. . As a result, since complicated adjustment work can be eliminated, the operability of the ultrasonic flaw detection apparatus using this composite ultrasonic probe 10 can be greatly improved. FIG. 4 is a block diagram showing the configuration of a control device 20 that operates this composite ultrasound probe 10.

The transmitting circuit 21 applies a pulse signal b to the transmitting transducer 12a of the first split type probe via the connecting terminal 17a at every prescribed period P. Further, the reception signal c output from the reception vibrator 12b via the connection terminal 17b is input to the reception circuit 22. The receiving circuit 22 removes the noise component of the input received signal c using a preset threshold voltage VSH, and applies it to the vertical axis of the CRT display 24 via the signal switching circuit 23 as a peak wave signal c1. Note that the peak wave signal c1 output from the receiving circuit 22
is output to, for example, a recorder via the defective gate circuit 25.

Similarly, the transmitting circuit 26 applies a pulse signal e to the transmitting transducer 13a of the second split type probe via the connecting terminal 18a at regular intervals P. Further, the reception signal f output from the reception vibrator 13b is input to the reception circuit 27. The receiving circuit 27 removes the noise component of the input received signal f using a preset threshold voltage VSH, and outputs the signal as a peak wave signal f1 to the signal switching circuit 23.
The voltage is applied to the vertical axis of the CRT display 24 through. Note that the peak wave signal f1 outputted from the receiving circuit 27 is outputted to, for example, a recorder via the defective gate circuit 28.

Furthermore, the output timing of each pulse signal b, e from each transmitting circuit 21, 26 is controlled by a synchronization circuit 29. A changeover switch 29a operated by the operator is connected to this synchronization circuit 29, and when this changeover switch 29a is turned on to the simultaneous excitation side, each pulse signal b, e is
As shown in a), they are output completely simultaneously. On the other hand, when the changeover switch 29a is turned on to the alternate excitation side, the pulse signals b and e each have a period of 1/1 as shown in FIG. 5(b).
The output is shifted by 2.

Furthermore, the synchronization circuit 29 sends output timing signals of the respective pulse signals b and e to the time axis circuit 30. The time axis circuit 30 applies a sweep signal corresponding to the distance d to the horizontal axis (time axis) of the CRT display 24 based on the input output timing signal. At the same time, a switching signal g is output to the signal switching circuit 23 at the timing when the distance d on the horizontal axis reaches the switching distance dC shown in FIG.
, the peak wave signal inputted to the peak wave signal c1 from the receiving circuit 22 corresponding to the first split type probe, and the peak wave signal input from the receiving circuit 27 corresponding to the second split type probe. Switch to f1. Further, each electronic circuit component is supplied with a driving voltage VC from a power supply circuit 31.

In such a control device 30, when the power is turned on with the changeover switch 29a of the synchronous circuit 29 turned on to the simultaneous excitation side, each pulse signal b, e is output from each transmitting circuit 21, 26 at the same timing. be done. As a result, each transmitting transducer 12a of the first and second split type probes,
Pulsed ultrasonic waves are output from 13a at the same timing. A part of the ultrasonic waves output from each transmitting transducer 12a, 13a is reflected by the mounting surface 4a, and the rest is reflected by the steel plate 4.
The light enters the center and is propagated toward each focal point 15 and 16. Then, the reflected waves reflected from the bottom surface of each receiving vibrator 12b, 1
3b. In addition, when a defect is encountered during propagation, the defect reflected wave reflected by the defect is transmitted to each receiving transducer 12.
b, 13b.

Therefore, each peak wave signal c1, f1 output from each receiving circuit 22, 27 corresponding to each of the first and second split type probes has a transmission pulse wave T as shown in FIG. , the surface reflected wave S, and the bottom reflected wave B, a defect wave F is generated due to the defect.

Each of the peak wave signals c1 and f1 is input to the CRT display 24 via the signal switching circuit 23, but the distance d is different from the switching distance (d=0) from the mounting surface 4a (d=0).
=dC), the signal switching circuit 23 is switched and connected to the receiving circuit 22 side in the time axis circuit 30.
During this period, a peak wave signal c1 corresponding to the received signal c of the first split type probe is displayed on the CRT display 24. As shown in FIG. 3, the flaw detection area AR of the first split type probe covers a short distance area near the surface (mounting surface 4a) of the steel plate 4, so it is difficult to detect defects caused by defects existing near the mounting surface 4a. The defective wave F can be reliably detected.

Furthermore, during the period when the distance d is from the switching distance (d=dC) to the bottom position (d=t), the signal switching circuit 23 is switched and connected to the receiving circuit 27 side in the time axis circuit 30. , during this period, the peak wave signal f1 corresponding to the received signal f of the second segmented probe is displayed on the CRT display 24. The flaw detection area BR of this second split type probe
As shown in FIG. 3, since it covers a long distance area near the bottom of the steel plate 4, it is possible to reliably detect a defect wave F caused by a defect existing near the bottom.

As described above, by using the composite ultrasonic probe 10 incorporating a plurality of split type probes with different focal positions, the composite ultrasonic probe 10 of the steel plate 4 can be detected without using a DAC circuit. Sufficient and uniform defect detection sensitivity can be obtained over a wide distance range from the mounting surface 4a of the feeler 10 to the opposite surface (bottom surface). Therefore, defect detection accuracy can be greatly improved. Next, a case will be described in which the changeover switch 29a of the synchronous circuit 29 is turned on to the alternate excitation side.

When the changeover switch 29a is turned on to the alternate excitation side, each transmitting circuit 21, 26 is turned on as shown in FIG. 5(b).
Pulse signals b and e whose period is shifted by 1/2 from each other
are the respective transmitting transducers 12a of the first and second split type probes,
13a. As a result, each transmitting transducer 12a,
The output timing of the ultrasonic waves in 13a is shifted. Therefore, both ultrasonic waves are prevented from interfering with each other. Therefore, the S/N ratio of each received signal c, f output from each split type probe can be improved, and as a result, defect detection accuracy can be further improved.

Note that in this case, the peak wave signals c1,
Since there is a timing difference between the peak wave signals c1 and f1, they are not displayed simultaneously on the CRT display 24, and the operator manually switches the signal switching circuit 23 to display each peak wave signal c1.
, f1 may be displayed alternately on the CRT display 24 to observe the defect wave F.

Further, when each pulsed ultrasonic wave outputted from each transmitting transducer 12a, 13a is incident on the steel plate 4, a portion thereof is reflected by the surface (mounting surface 4a). A part of the surface reflected wave is transmitted to each receiving transducer 12.
b, 13b. Therefore, each received signal c, f
As shown in FIG. 8, a surface reflected wave S appears in the peak wave signals c1 and f1 near the surface. If the surface reflected wave S is large, the defect wave F of a small defect generated near the surface will be included in the surface reflected wave S. The magnitude (height) of this surface reflected wave S increases as the incident angle of the ultrasonic wave becomes smaller, that is, as the focal position becomes farther away. As a result, the ultrasonic wave output from the transmitting transducer 13a of the second split type probe, which detects long-distance defects, is transmitted to the receiving transducer 12b of the first split-type probe, which detects defects at a short distance. Since the surface reflected waves of 1 are mixed in, a problem arises in that even if the first split type probe is used, defects in positions very close to the surface cannot be accurately detected.

However, since the output timings of the ultrasonic waves output from the transmitting transducers 12a and 13a of the first and second split-type probes are different, the receiving transducer of the first split-type probe The timing at which the surface reflected wave from the second split type probe is input to 12b and the input timing at which the surface reflected wave from the ultrasonic wave output by itself are input are shifted by 1/2 period. the result,
The surface reflected wave S of the second split type probe does not adversely affect the defect detection accuracy near the surface. Therefore, defects can be detected with higher accuracy.

Furthermore, although it has been explained that by turning the selector switch 29a to the alternate excitation side, it is possible to output ultrasonic waves alternately and prevent interference between the ultrasonic waves. It is possible to generate an interference phenomenon between ultrasonic waves to increase overall detection sensitivity at a long distance.

That is, as shown in FIG. 6(a), when each split type probe is operated independently with the changeover switch 29a set to the alternate excitation side, a short-distance probe with sensitivity characteristic C is generated. Assume that a first split-type probe and a second split-type probe for long distance use having sensitivity characteristics D exist. In this state, when the changeover switch 29a is turned to the simultaneous excitation side, the sensitivity characteristics of the respective received signals c and f may become the sensitivity characteristics G shown in FIG. 6(b).

Therefore, the vibration frequency of each vibrator 12a to 13b, the difference between each vibrator 12a to 13b, and the vibration frequency of each vibrator 1
If the distances between 2a to 13b and the surface 4a are adjusted so that the amplitudes of the respective reflected waves near the bottom of the steel plate 4 match in phase in a direction that emphasizes each other, the detection sensitivity of the corresponding position increases as a result. Conversely, at short distances, if the phases match in directions that cancel out each other's amplitudes, detection sensitivity will decrease. That is, the sensitivity characteristic G synthesized using the interference phenomenon can be arbitrarily set.

Note that the present invention is not limited to the embodiments described above. In the embodiment, the composite ultrasonic probe is constructed using two split probes, but a large number of split probes having different focal positions may also be used. In this case, since the overall flaw detection area is expanded, defects can be detected over a wider area with high precision.

Furthermore, since each split type probe is assembled into the same container 11 as one composite ultrasonic probe 10, handling of the probes is simplified and operation of the entire ultrasonic flaw detection apparatus is simplified. can significantly improve performance.

Furthermore, the method of arranging the transmitting transducers 12a, 13a and the receiving transducers 12b, 13b is not limited to the embodiment shown in FIGS. 1 and 2. For example, various methods can be considered, as shown in FIGS. 7(a) to 7(e). Then, the optimum arrangement method may be selected in consideration of the storage container, mounting location, etc. That is, what is important is that the focal positions of the segmented probes constituting the composite ultrasound probe should be different from each other. For example, FIGS. 7(a) to (c)
is an arrangement of each segmented probe in a horizontal row, as shown in Figure 7.
(d) and (e) of the same figure are arranged in two horizontal rows.

In each of the embodiments described above, the vibration frequencies of the transducers between the split probes were set to be equal to each other. By setting the vibration frequency of each vibrator 12a, 12b of the probe to be higher than the vibration frequency of each vibrator 13a, 13b of the second split type probe, which connects the focal point 16 at a position far from the mounting surface, more effects can be achieved. Defects can be detected visually.

That is, by making the thickness of each vibrator 12a, 12b of the first split type probe thinner than the thickness of each vibrator 13a, 13b of the second split type probe,
For example, the vibration frequency determined by the resonance frequency of each vibrator 12b, 12b of the split type probe is set to 5 MHz, and the vibration frequency of each vibrator 13a, 13b of the second split type probe is set to 2 MHz. . In this case, in order to avoid interference between ultrasonic waves within the steel plate 4, it is desirable to perform flaw detection using only alternate excitation.

As mentioned above, fine defects can be detected with high accuracy by increasing the vibration frequency, so the first split-type probe can be used to detect material mechanics at a relatively shallow position or surface near the mounting surface 4a of the steel plate 4. Harmful minute defects can be detected with higher precision. On the other hand, if the vibration frequency is lowered, it is difficult to attenuate, so using the second split type probe with a lower vibration frequency,
Relatively large defects deep in the steel plate 4 can be reliably detected.

That is, by incorporating a plurality of split type probes having different vibration frequencies into one container 11 in this way, flaw detection can be performed using ultrasonic waves at the optimum frequency depending on the type of defect, so that S/ N can be improved, and flaws ranging from minute defects near the surface of the steel plate 4 to large defects at deep positions can be reliably detected. Therefore, the defect detection ability is improved, and since the flaw detection operation is completed in one time, the flaw detection work efficiency can be further improved.

Furthermore, it is possible to further simplify the control device 20 that operates this composite ultrasonic probe 10. For example, the receiving circuits 22 and 27 receive input received signals c and f.
It is also possible to remove only the noise component using a simple filter and send it to the CRT display 24. Alternatively, the switching signal g may not be sent from the time axis circuit 30, and the signal switching circuit 23 may be manually switched by the operator as necessary. Furthermore, when only simultaneous excitation is performed, only one transmitting circuit is required instead of using the two transmitting circuits 21 and 26. In this way, it is possible to fully exhibit the functions of the composite ultrasonic probe 10 described above without using a complicated control device.

[0060]

As explained above, according to the composite ultrasonic probe of the present invention, a plurality of split type probes having different focal positions are assembled in the same container. Therefore, by dispersing each focal point position in the thickness direction of the object to be measured, defects can be detected with almost uniform detection sensitivity over a wide distance range including near and far distances in the thickness direction of the object to be measured. It is possible to expand the detection range and improve the detection accuracy.

Furthermore, since the vibration frequency of the split-type probe with a focus close to the mounting surface is higher than the vibration frequency of the split-type probe with a focus far from the mounting surface, the split-type probe with a focus close to the mounting surface Microscopic defects near the surface can be detected with higher accuracy, and large defects in deep positions can be detected more reliably using a split-type probe with a far focus.

[Brief explanation of the drawing]

FIG. 1 is a transparent perspective view showing a schematic configuration of a composite ultrasound probe according to an embodiment of the present invention;

[Figure 2] Schematic cross-sectional diagram showing the same example probe,

[Figure 3
] A diagram showing the relationship between the focal position of each split type probe and each detection sensitivity characteristic in the same example probe,

[Fig. 4] Block configuration diagram showing the control device of the probe of the same embodiment,

[Figure 5] A time chart showing pulse signals applied to the probe of the same example.

FIG. 6: Detection sensitivity characteristic diagram of each split type probe of a composite ultrasonic probe according to another embodiment of the present invention,

[Figure 7]
A diagram showing the arrangement state of each vibrator of a composite ultrasonic probe according to still another embodiment of the present invention,

[Figure 8] Schematic cross-sectional diagram showing a general split-type probe,

[Figure 9] Diagram for explaining the operation of the split type probe,

FIG. 10 is a defect detection sensitivity characteristic diagram of the split type probe.

[Explanation of symbols]

4... Steel plate, 4a... Mounting surface, 10... Composite ultrasound probe, 1
1... Container, 12a, 13a... Transmission vibrator, 12b, 13
b... Receiving transducer, 15, 16... Focus, 20... Control device,
21, 26... Transmitting circuit, 22, 27... Receiving circuit, 23...
Signal switching circuit, 24...CRT display, 29...synchronous circuit.

Claims (3)

[Claims] Claim 1: A plurality of split-type probes each having an ultrasonic transmitting transducer and a receiving transducer arranged so as to focus on different positions on a perpendicular line perpendicular to the mounting surface of the object to be measured. A composite ultrasonic probe characterized by being incorporated into a container. [Claim 2] A first split-type probe in which an ultrasonic transmitting transducer and a receiving transducer are arranged so as to focus on a first position on a perpendicular line perpendicular to the mounting surface of the object to be measured. and a second ultrasonic transmitting transducer and a receiving transducer arranged so as to focus on a second position different from the first position on a perpendicular line perpendicular to the mounting surface of the object to be measured. A composite ultrasonic probe characterized by incorporating a split type probe into the same container. 3. The vibration frequency of each vibrator of the split type probe that focuses at a position close to the mounting surface of the object to be measured is equal to the vibration frequency of each vibrator of the split type probe that focuses at a position far from the mounting surface. Claim 1 characterized in that the vibration frequency is set higher than the vibration frequency of
and a composite ultrasound probe according to claim 2.