JPS61240158A - Ultrasonic flaw detection method and apparatus therefor - Google Patents

Abstract

PURPOSE:To perform the flaw detection of an object to be inspected having a complicated surface configuration and difficult to mechanically follow, by performing scanning in such a state that the distance between the surface of the object to be inspected and an ultrasonic probe is kept constant and the probe is allowed to coincide with the normal line direction of the surface of the object to be inspected. CONSTITUTION:A transmitter 22 repeatedly applies a pulse to an ultrasonic probe 12 while the probe 12 emits an ultrasonic wave to an object 10 to be inspected and receives the reflected wave therefrom. This receiving signal is sent to a distance detection circuit 26 through a receiver 24 and an up-and-down drive apparatus 28 is controlled by the detection output corresponding to the time from the transmission of the ultrasonic wave to the reception thereof to keep the distance between the probe 12 and the surface of the object 10 to be inspected. The reflected wave from the object 10 to be inspected is sent to an angle comparator 32 through receivers 20A, 20B and amplifiers 30A, 30B and the shift between the normal line direction of the object 10 to be inspected and the transmitting/receiving direction of the probe 12 is detected and an angle control apparatus 34 is driven by the detected output and, by this method, the normal line direction of the surface of the object 10 to be inspected is allowed to coincide with the ultrasonic wave transmitting/receiving direction of the probe 12 to perform automatic ultrasonic flaw detection.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an ultrasonic flaw detection method and apparatus, and is particularly applicable to automatic ultrasonic flaw detection of objects with complex surface shapes that are difficult to mechanically copy, such as turbine blades. This invention relates to improvements in ultrasonic flaw detection methods and devices suitable for use.

[Conventional technology]

For the purpose of more precise ultrasonic flaw detection than in the past, as shown in FIG. The water immersion automatic flaw detection method, which performs flaw detection using water, is currently being used. Note that the ultrasonic probe 12 is scanned over the surface of the subject 10 by a scanning device 16. The reason why ultrasonic flaw detection is performed by water immersion is that the water 14 allows the ultrasonic waves transmitted from the ultrasonic probe 12 to enter the object 10 stably, and the ultrasonic echoes reflected from the object 10. This is because it is stable as an acoustic coupler for receiving by the ultrasonic probe 12. Further, since the water 14 has a low absorption rate of ultrasonic waves, high-frequency ultrasonic waves can be used. Furthermore, water 1
4, it is difficult to use an acoustic lens that utilizes the law of refraction of ultrasound, and it is possible to narrow down the ultrasound beam to a smaller size. Therefore, the water immersion automatic flaw detection method can provide high accuracy that cannot be obtained with the direct contact method, as well as highly reproducible and reliable flaw detection results. On the other hand, in the water immersion automatic flaw detection method, the transmitted ultrasonic beam is focused by an acoustic lens, and the focus of the focused ultrasonic beam is used for flaw detection. It is necessary to maintain the distance , and to align the direction of the central axis of the ultrasound beam with the normal direction of the surface of the subject 10 . Therefore, in order to accurately detect defects in the object 10 using the water immersion automatic flaw detection apparatus applying the water immersion automatic flaw detection method, it is necessary to constantly monitor the position and orientation of the ultrasonic probe 12 relative to the surface of the object 10. It is necessary to ensure that the ultrasound probe 1
The scanning device 16 that performs the second scan is required to have high accuracy and stability.

[Problems to be solved by the invention]

However, in the conventional water immersion automatic flaw detection method, the distance and angle of the ultrasonic probe 12 with respect to the surface of the object 10 are usually determined geometrically, that is, mechanically.
When the surface shape of the object 10 is not flat but irregular, searching the object 10 while maintaining constant conditions, distances, and angles requires a complex tracing device and requires a general-purpose method. It is difficult to make a certain flaw detection device.Furthermore, if the position and posture of the ultrasonic probe 12 collapses due to unavoidable troubles such as mechanical imaging during flaw detection of the object 10, the ultrasonic probe 12 Since the probe 12 does not have a self-reset function, it has had problems such as the need to constantly monitor whether flaw detection is being performed normally in order to obtain reliable flaw detection results. .

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and the present invention provides ultrasonic flaw detection with high precision even for objects with complex surface shapes that are difficult to mechanically copy. In the ultrasonic flaw detection method, an ultrasonic probe, which is a means for transmitting and receiving ultrasonic waves, transmits ultrasonic waves to an object to be inspected, and the ultrasonic waves reflected by the object are received by a first ultrasonic receiving means. From an ultrasound signal received by the ultrasound probe and at least two receivers that are second ultrasound reception means other than the ultrasound probe, The distance between the surface of the object and the ultrasonic probe is determined, and the distance between the normal direction of the surface of the object and the ultrasonic probe is determined from the difference in the intensity of the ultrasonic signals received by at least two other receivers. By detecting the angular deviation between the transmitting and receiving directions of the ultrasonic probe and making adjustments based on these measurement results, the distance between the object surface and the ultrasonic probe can be kept constant, and
The above object is achieved by performing scanning while aligning the sending and receiving directions of the ultrasonic probe with the normal direction of the surface of the subject. Further, the present invention provides an ultrasonic flaw detection device that includes an ultrasonic transmitting means for transmitting ultrasonic waves to a subject and a first ultrasonic receiving means for receiving ultrasonic waves in a substantially normal direction of the surface of the subject. a tentacle, an electric pulse transmitting means for transmitting an electric pulse to the ultrasonic transmitting means, an M1 amplifying means for amplifying the ultrasonic signal received by the ultrasonic probe which is the first ultrasonic receiving means; a second ultrasonic receiving means that is held integrally with the first ultrasonic receiving means and receives ultrasonic waves at at least two locations in a direction different from the ultrasonic receiving direction of the first ultrasonic receiving means; a second amplifying means for amplifying the ultrasonic signal received by the two ultrasonic receiving means; and a second amplifying means for amplifying the ultrasonic signal received by the first ultrasonic receiving means; distance detection means for determining the distance to the probe; and an output signal of the distance detection means to maintain a constant distance between the surface of the object and the ultrasonic probe which is the ultrasonic transmitting means and the first ultrasonic receiving means. distance adjusting means for controlling the distance, angle comparing means for detecting a deviation between the normal direction of the object surface and the transmitting and receiving directions of the ultrasonic probe from the output signal of the second amplifying means; The above object has been achieved by a device comprising an angle adjusting means for aligning the normal direction of the surface of the subject with the transmitting and receiving directions of the ultrasonic probe using the output signal of the comparing means. [Operation] The operation of the present invention will be explained in detail below. FIG. 1 shows the basic configuration of ultrasonic flaw detection according to the present invention. As shown in FIG. 1, an ultrasonic probe 12, which is a first ultrasonic receiving means, is disposed facing a subject 10, and a second
A pair of receivers 2OA and 20B, which are ultrasound receiving means, are arranged around the ultrasound probe 12 so as to operate integrally with the ultrasound probe 12. In the present invention, when the ultrasonic probe 12 moves to another position, the distance between the ultrasonic probe 12 and the subject 10, the direction of the ultrasonic beam, and the normal line of the subject 10 are determined. It is characterized by performing flaw detection while keeping the angle constant. In the present invention, a transmitter 2 which is an electric pulse transmitting means is used.
2 transmits electric pulses to an ultrasonic probe 12, which is an ultrasonic wave transmitting means, at a fixed repetition rate, and the electric pulses cause the ultrasonic probe 12 to transmit ultrasonic waves toward the subject 10. The ultrasonic wave reflected by the subject 10 is received by the ultrasonic probe 12 which is a first ultrasonic receiving means, and the received signal received by the ultrasonic probe 12 is received by a first amplifying means. A time measuring circuit 26 serving as a distance detecting means
The time from transmitting to receiving the ultrasound from a part of the output signal of the receiver 24 is measured, and the time measured by the clock circuit 26, that is, the time between the ultrasound probe 12 and the subject 1o.
A vertical drive device 28, which is a distance adjustment means, drives the ultrasonic probe 12 vertically so as to maintain a distance from the ultrasonic probe 12. The ultrasound reflected by the subject 10 is received by a pair of receivers 2OA and 20B, which are second ultrasound receivers, and the receiver 20A
, 20B is amplified by amplifiers 30A and 30B, which are second amplification means, and the amplifier 30A and 30B
By comparing the output signals, the comparator 32, which is an angle comparing means, detects the deviation between the normal direction of the surface of the subject 10 and the transmission and reception directions of the ultrasound probe. Then, from the output signal of the comparator 32, the angle side t, which is the angle adjustment means, is
The Ili device 34 performs automatic ultrasonic flaw detection by matching the normal direction of the surface of the object 1o with the ultrasonic transmission and reception directions of the ultrasonic probe 12. Note that the recording system 36 is connected to the subject 1o together with the receiver 24.
Draw and record the distribution map of defects inside. The transmitter 22 repeatedly transmits electric pulses to the ultrasound probe 12 in order to detect a defective part in the subject 10 . Further, the receiver 24 is often connected to one ultrasound probe 12 together with the transmitter 22, and therefore, the ultrasound probe 12 is often used for both transmission and reception. Here, the principle of the present invention will be explained based on FIGS. 2 and 3. As shown in FIG.
Inside, receivers 2OA and 20B that operate integrally with the ultrasound probe 12 are arranged around the ultrasound probe 12. The ultrasonic probe 12 transmits ultrasonic waves toward the subject 10, and the pair of receivers 2OA and 20B receive the ultrasonic waves reflected by the subject 10. The reflection intensity distribution of the ultrasonic waves reflected by the object 1° is shown in Figure 3 (A).
As shown in (B), when the direction of the central axis of the incident wave 40 coincides with the normal line 46 of the subject 10, the incident ultrasonic wave 40 to the subject 10 is Scattering occurs at the point 42, and the normal line 46 of the object 10 as shown in FIG.
A scattered wave 44 having a symmetrical reflection intensity distribution is generated, but if the direction of the central axis of the incident wave does not coincide with the normal 46 of the subject 10, as shown in FIG. does not have a reflection intensity distribution that is symmetrical about the normal 46. Therefore, the angle control WJ device 34 receives the scattered waves 44 at the receivers 2OA and 20B so that the output intensities of the received signals are the same.
If the ultrasound probe 12 is operated in this manner, the transmission and reception directions of the ultrasound probe 12 can be made to face perpendicularly to the surface of the subject 10. Therefore, even if the test object 1o has an irregular surface shape, stable flaw detection results can be obtained. Note that the axis of the normal line 46 that can be detected by the pair of receivers 2OA and 20S in FIG. 12 is the direction of movement on the paper surface;
That is, only in the X direction. However, if the other receivers 21A and 21B are installed perpendicularly to the plane of the paper, the axis of the normal 46 in the direction perpendicular to the plane of the paper, that is, the Y direction, can also be detected.

【Example】

Embodiments to which the present invention is applied will be described in detail below. As shown in FIG. 4, this embodiment includes a holder 50 attached to an appropriate scanning mechanism (not shown), and a rack processing (not shown) provided through the holder 50. The lifting shaft 52 is raised and lowered by gears (not shown), and the driving force is applied to the gears (not shown).
2; a shaft holder 54 attached to the lower part of the lifting shaft 52 and holding and fixing the shaft 60; a shaft 60 rotatably connecting the shaft holder 54 and the first rotation unit 56; The first rotation unit 56 has a structure capable of rotating around a rotation axis 60, and a rack and gears (not shown) built in the first rotation unit 56 are used to rotate the first rotation unit 56.
a motor 72 that applies driving force to the rotation unit 56 and rotates the M1 rotation unit 56 around the shaft 60;
a shaft 62 provided below the first rotation unit 56 and rotatably connecting the first rotation unit 56 and the second rotation unit 58; and a second rotation unit configured to rotate around the shaft 62. 58 and a rack and gears (not shown) built into the second rotation unit 58 apply a driving force to the second rotation unit 58 to rotate the second rotation unit 58 about the shaft 62. a motor 74, an ultrasonic probe 12 attached to the lower part of the second rotation unit 58 for transmitting and receiving ultrasonic waves to the subject 10, and a second ultrasonic probe disposed around the ultrasonic probe. The object 10 is attached to the lower part of the rotating unit.
two pairs of receivers 20A that receive ultrasound reflected from the
20B, 21A, 21B, a transmitter 22 that transmits electric pulses to the ultrasound probe 12, and the ultrasound probe 1.
A receiver 24 amplifies the received signal received at 2, and measures the time for the ultrasound to travel back and forth in the darkness from the output signal of the receiver 24 to the ultrasound probe 12 and the subject 10, and calculates the time. A clock circuit 26 that outputs an analog value or a digital signal; a probe vertical drive circuit 28A that sends a drive signal to the motor 70 to raise and lower the lift axis so that the output of the clock circuit 26 is constant; and a probe vertical drive circuit 28A that raises and lowers the lift shaft; 24 as well as a recording system 36 for drawing and recording a distribution map of defects in the object 10;
and each amplifier 30A that amplifies the ultrasound signal transmitted by the ultrasound probe 12, reflected by the object 10, and received by the receivers 2OA, 208.21A, and 21B,
30B, 31A, 31B, and a comparator 32A that compares the outputs of the amplifiers 30A and 308 to detect an angular deviation in the X direction between the ultrasound probe 12 and the normal 46 of the subject 10, and the amplifier a comparator 32B that compares the outputs of 31A and 31B and detects the angular deviation in the Y direction between the ultrasound probe 12 and the normal line 46 of the subject 10; an angle control circuit 34A that drives the motor 74 to match the angle in the X direction between the ultrasonic reception direction of the child 12 and the normal 46 of the surface of the subject 10;
An angle control circuit 34B that drives the motor 72 to match the angle in the Y direction between the ultrasound receiving direction of the ultrasound probe 12 and the normal 46 of the surface of the subject 10 based on the output of the comparator 32B. It is configured. The receivers 2OA, 20B and the receivers 21A, 21
B are in pairs, and the pair of receivers 20A and 20B and the pair of receivers 21A and 21B are disposed perpendicularly and intersectingly in the X and Y directions, respectively, as shown in FIG. It is attached to the lower part of the second rotation unit 58. The ultrasonic probe 12 and the receiver 20A. Water immersion ultrasonic probes 20B, 21A, and 21B are used. In this case, the acoustic coupler is water 14. The distance between the ultrasound probe 12 and the subject 10 can be set arbitrarily, and the ultrasound probe 12 can be directed in any direction. The transmitter 22 and the receiver 24 are connected to one ultrasound probe 12. Therefore,
This ultrasonic probe 12 serves both as a transmitter and a receiver. The operation of this embodiment will be explained. The transmitter 22 applies electrical pulses to the ultrasonic probe 12 used in water immersion at a constant repetition period. The ultrasonic probe 12 transmits ultrasonic waves by applying the electric pulse. The ultrasound reflected by the subject 10 is received by the ultrasound probe 12 . The received signal is suitably amplified by the receiver 24. The transmitter 22 sends an electric pulse E to the ultrasound probe 12.
At the same time as transmitting P, a synchronizing pulse SP is transmitted to the clock circuit 26. The synchronization pulse SP transmitted from the transmitter 22 is input to the clock circuit 26, and a signal waveform obtained by amplifying the ultrasonic wave received by the ultrasound probe 12 by the receiver 24 is input. be done. The clock circuit 26 is
The transmitter 22 transmits the electric pulse EP according to the input synchronization pulse and the signal waveform, and then the ultrasound pulse is reflected on the surface of the object 10 and returns to the ultrasound probe 1.
Measure FRrrs until returning to 2. That is, the time measured by the clock circuit 26 becomes a time signal T proportional to the distance between the surface of the subject 10 and the ultrasound probe 12. Further, the clock circuit 26 outputs the time signal T to the probe vertical drive circuit 28A as an analog signal or a digitized signal. The probe vertical drive circuit 28A sends a drive signal M to the motor 70 so as to keep the input time signal T at a constant value.
Send A. The motor 70 raises and lowers the elevating shaft 52 in response to the drive signal MA to keep the time signal T constant. Therefore, if the signal T at that time is kept constant, the object 1o
The distance between the ultrasonic probe 12 and the ultrasonic probe 12 is kept constant. On the other hand, the pair of receivers 2OA and 20B have the above-mentioned No. 2.3.
A scattered wave 44 generated when an incident wave 40 of an ultrasonic pulse transmitted from the ultrasonic probe 12 shown in the figure is reflected on the surface of the object 10 is received.
The ultrasound signals generated by the scattered waves 44 received by A and 20B are similarly amplified by amplifiers 30A and 30B, respectively. The comparator 32A compares the amplitudes of the ultrasonic signals amplified by the amplifiers 30A and 30B, and if there is a difference in the amplitude, the difference in the amplitude is sent to the angle control circuit 34A. output as a voltage signal, current signal, or digital signal. The angle control circuit 34A transmits the drive signal MB to the motor 74 so that the input signal due to the difference in amplitude becomes zero. The motor 7
4 rotates the second rotation unit 58 around the shaft 62 by the drive signal Me, so that the amplitudes of the respective ultrasound signals by the scattered waves 44 received by the receivers 2OA and 20B are the same. The second rotation unit 58 is in a position where
is adjusted. Further, the other pair of receivers 21A and 21B also receive the scattered waves 4.
Each of the received ultrasound signals is received by an amplifier 31A and 131B, as in the case of the pair of receivers 2OA and 20B. The comparator 32B compares the magnitude of the amplitude of each of the amplified signals, and the angle control circuit 34 controls the amplitude so that the difference in the magnitude of the amplitude becomes zero.
B sends the drive signal MO to the motor 972. The motor 72 rotates the first rotation unit 56 about the axis 6o, so that the amplitudes of the respective ultrasound signals generated by the scattered waves 44 received by the receivers 21A and 21B become the same. The first rotation unit 56 is adjusted to the position. Therefore, by adjusting the first rotation unit 56 and the second rotation unit 58, the central axis direction of the ultrasound beam transmitted from the ultrasound probe 12 and the normal to the surface of the subject 10 can be adjusted. 46 directions can be matched. As explained above, according to this embodiment, the specimen 1 in the water 14
When scanning above 0, the distance between the water-immersed ultrasonic probe 12 and the subject 10 can be maintained at a constant value, and the ultrasonic probe 12 can be moved to the inspection area on the surface of the subject 10. can be vertically opposed. Therefore, it is possible to perform stable automatic ultrasonic flaw detection. Note that the flaw detection results obtained when the ultrasonic probe 12 and the object 1o are maintained in this state are recorded in the recording system 36. In the embodiment, the receivers 2OA, 20B, 21A
, 21B had two pairs of receivers, but the number of receivers only needs to be two or more. For example, if the surface of the subject 1° changes only in the X direction but not in the Y direction, one pair of receivers is sufficient. Only the receiver is required. Further, in the above embodiment, the ultrasonic probe 12 used for both transmission and reception is used, but the ultrasonic probe is not limited to this. Other ultrasound transmitting means and ultrasound receiving means may be used. Furthermore, in the embodiment, the receiver 20A120B,
Although water immersion ultrasonic probes are used for 21A, 21B and the ultrasonic probe 12, the receiver and the ultrasonic probe are not limited to this, and other receivers and ultrasonic probes are used. But that's fine. Further, any type of receiver can be used as long as it can efficiently receive the scattered waves 44 generated on the surface of the subject 10. Further, in the above embodiment, water 14 was used as the acoustic coupler, but the acoustic coupler is not limited to water 14.
Other acoustic coupling bodies may also be used.

【Effect of the invention】

As explained above, the present invention enables highly accurate (ultrasonic) testing of objects with complex surface shapes that are difficult to mechanically copy, such as turbine blades, and thus enables conventional water immersion automatic ultrasonic testing. It has the excellent effect of providing high precision, reproducibility, and reliable flaw detection that cannot be obtained with flaw detection technology.

[Brief explanation of the drawing]

FIG. 1 is a block diagram including a cross-sectional view showing the basic structure of the present invention; FIG. 2 and FIG. 3 (A) and (B) are cross-sectional views for explaining the principle; FIG. 4 is a perspective view partially including a block diagram showing the configuration of an embodiment of the present invention, and FIG. 5 is a sectional view showing a conventional ultrasonic flaw detection device. 10... Subject, 12... Ultrasonic probe,
14...Wednesday, 20...Receiver, 22.
...Transmitter, 24...Receiver, 26...Clock circuit, 28...Vertical drive device, 28A...
Probe vertical drive circuit, 30A, 30B, 31A, 31 B... amplifier, 32
．． 32A, 32B...Comparator, 34...Angle control device, 34A, 34B...Angle control circuit, 70.72.74...Motor.

Claims (2)

[Claims] (1) The ultrasonic probe, which is a means for transmitting and receiving ultrasonic waves, transmits ultrasonic waves to a subject, and the ultrasonic waves reflected by the subject are transmitted to the ultrasonic wave, which is a first ultrasonic receiving means. A probe and at least two receivers that are second ultrasound receiving means other than the ultrasound probe receive the ultrasound signal, and the ultrasound signal is detected from the ultrasound signal received by the ultrasound probe. The distance between the surface and the ultrasonic probe is determined, and from the difference in the intensity of the ultrasonic signals received by at least two other receivers, the distance between the normal direction of the object surface and the ultrasonic probe is determined. By detecting the angular deviation between the transmitting and receiving directions, and making adjustments based on these measurement results, the distance between the object surface and the ultrasonic probe is kept constant, and the transmitting and receiving directions of the ultrasonic probe are adjusted. An ultrasonic flaw detection method characterized in that scanning is performed while the direction coincides with the normal direction of the surface of the object to be inspected. (2) An ultrasonic probe that is an ultrasonic transmitting means for transmitting ultrasonic waves to a subject and a first ultrasonic receiving means for receiving ultrasonic waves in a direction approximately normal to the surface of the subject, and the ultrasonic transmitting means. an electric pulse transmitting means for transmitting an electric pulse to the means; a first amplifying means for amplifying the ultrasonic signal received by the ultrasonic probe which is the first ultrasonic receiving means; and the first ultrasonic receiving means. a second ultrasonic receiving means that is held integrally and receives ultrasonic waves at at least two locations in a direction different from the ultrasonic receiving direction of the first ultrasonic receiving means; a second amplification means for amplifying the ultrasound signal; and a second amplification means for amplifying the ultrasound signal;
distance detecting means for determining the distance between the ultrasonic probe, which is the ultrasonic receiving means; and an ultrasonic wave, which is the ultrasonic transmitting means and the first ultrasonic receiving means, between the surface of the subject and the ultrasonic transmitting means and the first ultrasonic receiving means, based on the output signal of the distance detecting means. distance adjusting means for controlling the distance to the probe to be constant; and detecting a deviation between the normal direction of the object surface and the transmitting and receiving directions of the ultrasonic probe from the output signal of the second amplifying means. and angle adjusting means for aligning the normal direction of the surface of the subject with the transmission and reception directions of the ultrasound probe using the output signal of the angle comparison means. Ultrasonic flaw detection equipment.