JPH0157735B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ultrasonic flaw detection apparatus for detecting internal defects, discontinuous shaped parts, etc. of structural members by an aperture synthesis type ultrasonic flaw detection method.

[Technical background of the invention and its problems]

As shown in Fig. 1, the aperture synthesis type ultrasonic flaw detection method uses a single transducer probe 2 for transmitting and receiving ultrasonic waves from the surface of an object 1 to be inspected, such as a structural member.
The ultrasonic beam is incident in a wide range of angular directions toward the inside of the device, and at the same time, ultrasonic reflected waves from internal defects 3 etc. that are reflected from a wide range of angular directions are detected, and these detected reflected waves are used for ultrasonic transmission and reception. Based on the movement position detection signal of the probe 2, the movement range of the probe 2 on the surface of the object 1 to be inspected is calculated from the beam path time t of the reflected wave from the internal defect 3 of the object 1 to be inspected. It performs detection.

The feature of this method is that an ultrasonic beam is made incident on the inside of the object to be inspected 1 in a wide range, and reflected waves of the incident ultrasonic beam from within the material are detected over a wide range.

On the other hand, since internal defects in an object to be inspected generally have a reflection directivity with respect to incident ultrasonic waves, it is often impossible to efficiently reflect ultrasonic waves from any direction in the direction of incidence.

For example, crack-like defects caused by welding defects have strong reflection directivity. Therefore, in this method, it is important to have a wide directivity when transmitting and receiving ultrasonic waves, and to transmit and receive ultrasonic waves with high sensitivity.

However, in conventional aperture synthesis type ultrasonic flaw detection equipment, as shown in Figure 2a, the directivity angle θ of the conventional ultrasonic probe 2 is widened, and reflections from a wide range of areas are detected by one ultrasonic transmission and reception. Since the waves are detected, the detected signal levels of the ultrasonic reflected waves E from the internal defects 3a, 3b, 3c and 3d located at various locations are small as shown by Sa, Sb, Sc, and Sd in Fig. 2b, and each The received signals of ultrasonic reflected waves from the internal defects 3a and 3d cannot be detected with a sufficiently high S/N ratio.

This is because the directivity during transmission and reception of ultrasonic waves is widened, and one of the major causes is that the level of the transmission and reception signals to each internal defect decreases.

[Purpose of the invention]

The present invention has been developed in view of the above circumstances, and it is an object of the present invention to perform ultrasonic wave transmission at a high level in aperture synthesis type ultrasonic flaw detection, and to detect reflected waves from a desired flaw detection area within the inspected body with high sensitivity. The aperture synthesis method enables high-precision flaw detection with less influence of reflection directivity such as internal defects within the inspected object, and also allows detection of ultrasonic reception signals at different positions without moving the probe. The purpose is to provide an ultrasonic flaw detection device based on

[Summary of the invention]

That is, in order to achieve the above object, the present invention uses an array type probe in which a large number of transducers for transmitting and receiving ultrasonic waves are arranged in parallel, and several adjacent transducers are controlled by phase control. The ultrasonic waves are excited, electronically condensed into a beam as in the case of sector scanning by electronic scanning, and the ultrasonic waves are oscillated and scanned in a fan shape to transmit the ultrasonic waves and receive them using a specific single transducer. The signals received in each direction of the ultrasonic beam by sector scanning are sequentially added and combined to form a detection signal. This allows a detection output to be obtained at a high level and with high sensitivity, and by selecting a group of vibrators to be excited, it is possible to change the ultrasonic transmission position without moving the probe position. be.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained in Figures 3 to 7.
This will be explained with reference to the figures.

FIG. 3 is a block diagram showing an example of the configuration of the present invention.

The first feature of the present invention is to use an array type probe in which a plurality of transducers for transmitting and receiving ultrasonic waves are arranged in parallel in a straight line as a probe for transmitting and receiving ultrasonic waves. For ultrasonic transmission, similar to electronic scanning, for example, multiple adjacent transducers are excited by phase control to perform ultrasonic scanning in arbitrary directions and ranges, and for reception, an arbitrary single transducer is used. The main point is that ultrasonic flaw detection is performed using the aperture synthesis method.

Another feature is that electronic scanning type ultrasonic flaw detection is possible by delaying the ultrasonic transmission direction and transmitting the ultrasonic transmission pulse that excites the array type probe to each of the transducers. The point is that the phase can be controlled in the same way as the method, and it can be controlled arbitrarily.

To explain the configuration of FIG. 3, reference numeral 31 is an array type probe formed by arranging a large number of transducers 31 ₁ to 31 _o in parallel at a predetermined pitch in a straight line.
Reference numeral 32 denotes a transmitter group, which narrows the ultrasonic waves into a beam shape in a set direction according to a signal from a delay time controller 34 based on a signal from a transmitting direction setting device 33 that sets the transmitting direction of the ultrasonic beam, and transmits it. Pulses can be sent to the vibrators 31 ₁ to 31 _o to cause waves.

That is, the wave transmission direction setting device 33 is used to set the position of the probe 31 and in which direction the ultrasonic beam is to be transmitted, and also outputs a signal according to the settings. Settings such as position shifting and sector scanning at each transmission position can also be performed.

Further, the transmitter group 33 provides an excitation pulse to each of the oscillators 31 ₁ to 31 _o in correspondence with each of the oscillators 31 ₁ to 31 _o , and the delay time controller 34 provides a pulse for excitation to each of the oscillators 31 1 to 31 o. A device that controls a delay time corresponding to the excitation timing of each of a set of a predetermined number of adjacent vibrators to be excited so that the ultrasonic beam can be transmitted in the wave transmission direction in accordance with the output signal of the wave direction setting device 33. It is.

Therefore, if the transmitter group 32 is composed of transmitters equal to the number of transducers 31 ₁ to 31 _o , the delay time controller 34 is applied to one set of transducers corresponding to the transmission position. functions so that the output of is input,
In addition, if it is configured with the number of transmitters corresponding to the number of transducers for one set and is configured to selectively connect the transducer group corresponding to the transmission position of the ultrasonic beam, it is possible to connect to a predetermined transmitter. The configuration is such that a predetermined output of the delay time controller 34 is provided in a corresponding manner.

A receiver 35 receives a received signal of an ultrasonic reflected wave received by an arbitrarily selected transducer 31 ₁ of the probe 31 and amplifies it. 36 is an adder, and each time the wave transmission direction changes according to the signal from the wave transmission direction setting device 33, the receiver 35
It is possible to write the received signal waveforms output from the receiver and add the waveforms.

Note that the delay time controller 34 in the adder 36
The signal from is used as a reference for wave transmission timing in each wave transmission direction.

In the configuration example of the present invention, the adder 36 digitizes the received signal waveform at high speed and adds the digital amount, but the received signals may be added using other addition methods. Also, adder 3
For the received signal group added in step 6, the summed waveform is outputted and the contents of the adder 36 are cleared when scanning of the scanning range by changing the desired ultrasonic wave transmission direction is completed.

In addition, the outputted addition waveform is processed in the same way as in the normal aperture synthesis type ultrasonic flaw detection method, and is processed based on the position of the probe 31 and the receiving transducer 31 ₁
It is possible to perform calculations on the position, shape, etc. of the reflection source inside the subject's body as well as the position of the object, and display the image, for example.

Next, the operation of this apparatus having the above configuration will be explained.

In this device, the ultrasonic wave transmission direction can be arbitrarily selected using the same principle as the electronic scanning method.
High-level ultrasonic waves can be transmitted in the set transmission direction.

That is, when the wave transmission direction setting device 33 generates a signal for obtaining a desired wave transmission direction, this signal is given to the delay time controller 34, and the signal is sent to the delay time controller 34.
4 provides an output to the transmitter of the transmitter group 32 corresponding to each of the oscillators in the set with a delay time to be given to each of the oscillators in the set in order to obtain the wave transmission direction.

On the other hand, the signal indicating the transmission position is sent to the transmission direction setting device 3.
Since the transmitter group 32 is selected in such a way that excitation pulses are given to one set of transducers corresponding to the transmitting position, each output of the delay time controller 34 is output from the corresponding transmitter. Here, an excitation pulse is applied from each transmitter to a corresponding vibrator with a delay time corresponding to the output, and the vibrator is excited.

Therefore, each of the selected set of transducers is excited at the input timing of the excitation pulse, and as a result, phase-controlled ultrasonic waves are transmitted from each set of transducers, and each ultrasonic wave is interfere with each other to form an ultrasonic beam, which is transmitted in the set direction.

Therefore, in this device, the transmitting direction setting device 33
is set to perform a sector scan, and as shown in Figure 4 a.
Sector scan is performed by scanning the ultrasonic beam UB in a fan shape as shown in the figure.

Then, as shown in FIG. 4b, the ultrasonic reflected wave UE within the range of this sector scan is received using an arbitrarily selected transducer of the probe 31, and is sent to the adder via the receiver 35. 36 and store it here.

This is performed for each wave transmission direction in the sector scan, so that the adder 36 adds and stores the received signals that are received one after another.

Therefore, when the sector scan at one position is completed, the added received signal waveform has the same effect as receiving total reflected waves from each transmission direction in the fan-shaped scanning range by this sector scan. will have.

When one sector scan is completed, the adder 36
The contents of are output and cleared.

The above routine is shown as a flowchart in FIG. 4c.

FIG. 5 is a diagram showing an example of internal defect detection in the object to be inspected 1 using the apparatus of the present invention. As shown in FIG. Ultrasonic beam UB from a predetermined position of the device 31
It transmits waves while performing sector scanning.

Now, if there are internal defects as shown at 3a, 3b, 3c, and 3d in the object to be inspected 1, as the ultrasonic beam scans, the direction in which no defects exist as shown in [1] in Fig. 5b is Reflected waves consisting mainly of noise components without strong reflected waves, and accompanied by strong reflection from the defective part in the direction where the defect exists [2],
Reflected waves such as [3] and [4] are sequentially detected. Here, Sa represents a reflected wave reflected from the internal defect 3a, Sb from the internal defect 3b, Sc from the internal defect 3c, and Sd from the internal defect 3d.

Therefore, as the sector scan is performed, the reflected waves in the ultrasonic beam transmission direction are sequentially detected, added and stored in the adder 36 in correspondence with the distance, and when the sector scan is completed, the added storage contents are stored. Output.

According to this method, the ultrasonic beam during transmission is in a specific direction, so the ultrasonic beam in the transmission direction has a high level, and the reflected waves from internal defects in the transmission direction are also noise components. will be at a high level.

Furthermore, when the reflected waves for each transmission direction are sequentially added by the adder 36, signals with random phases such as noise components are further reduced, and only the received signal from the defective part is detected with high sensitivity. The result is a summation waveform. Therefore, a received reflected wave signal with a good S/N ratio can be obtained.

Further, as a modification of the present invention, as shown in FIG. 6, receivers 35 ₁ to 35 _o and adders 36 ₁ to 36 _o are provided for a plurality of transducers 31 ₁ to 31 _o , respectively, so that the sectors of the ultrasonic beam are If the reflected waves are received by each of the transducers 31 ₁ to 31 _o during scanning, it is possible to simultaneously obtain summation waveforms at a large number of receiving positions. Flaw detection can be performed quickly.

In addition, in the embodiments explained in FIGS. 3 to 5, reception was carried out by selecting an arbitrary transducer of the probe, but as shown in FIGS. 7a, b, and c, The sound wave beam UB is transmitted in sectors at a fixed position such as UB _t , and the receiving transducer is changed successively to receive the reflected wave UB _r at that position, and the received signals at each reception position are added. It is also possible to obtain each signal waveform.

This makes it possible to obtain summed signal waveforms from many detection positions without moving the probe 31, which improves flaw detection speed and allows the position of the receiving transducer to be given with high precision. , arithmetic processing of received signals becomes easier, and processing accuracy improves.

Furthermore, by arbitrarily selecting a group of transducers when transmitting ultrasonic waves using the apparatus of the present invention, the point of incidence of the ultrasonic waves on the object to be inspected can be changed at any time, and the ultrasonic beam can be focused as necessary. It is possible to perform more precise flaw detection according to the shape and dimensions of the object to be inspected.

In addition, even if the ultrasonic beam incident point moves depending on the ultrasound transmission direction, the receiving transducer may be selected to correspond to the ultrasonic beam incident point, or the receiving transducer position and ultrasound If calculation is performed using the relative distance of the beam incident point position, it becomes easy to detect the defect position with high precision through signal processing.

Furthermore, it is also possible to perform transmission and reception completely separately by not including the receiving transducer in the transmitting transducer group.

〔Effect of the invention〕

As described in detail above, the present invention includes an array type probe in which a large number of transducers are arranged in parallel for transmitting and receiving ultrasonic waves, and an ultrasonic beam that is excited by controlling the phase of the plurality of transducers in this probe. A device that transmits ultrasonic beams in multiple directions by electronic scanning, selects any one of the transducers, uses the selected transducer for reception, and transmits the ultrasonic beam in each direction of the transducer. The ultrasonic beam is sequentially transmitted in multiple directions and the reflected wave is detected by an arbitrary transducer, and the ultrasonic beam is transmitted in each direction. Since the ultrasonic reception signal is obtained by the aperture synthesis method by sequentially adding and synthesizing the reception signals, the ultrasonic beam is transmitted in the form of a beam, so the level of the ultrasonic beam becomes high, and therefore it is difficult to detect the ultrasonic wave from the defective part. In addition to the reflected waves being at a higher level than the noise components, the ultrasonic beam is sequentially transmitted in multiple directions by electronic scanning, making it possible to detect defects over a wide range, making it possible to detect minute defects that were previously difficult to detect. It is now fully possible to detect flaws in materials with high ultrasonic attenuation, and in cases where the ultrasonic reflection source such as a defect has reflection directivity and normally reflects ultrasonic waves only from a specific angle. However, by changing the ultrasonic transmission position arbitrarily by selecting the vibrator group to be excited, it is possible to perform flaw detection with high sensitivity. Since the waves are sequentially added and synthesized, random noise components are reduced, and signals from reflection sources can be detected with high sensitivity. Also, since the receiving transducer can be arbitrarily selected, the probe Since it is possible to obtain a combined signal of each of the received signals detected at many positions without moving the probe, the number of times the probe is moved for aperture synthesis can be reduced, and flaw detection can be performed quickly. Furthermore, since the probe does not need to be moved, it is possible to provide an ultrasonic flaw detection apparatus that has features such as improved positional accuracy and higher flaw detection accuracy.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining a conventional example, Figures 2a and b are diagrams showing flaw detection by the conventional method and the detected received signal, and Figure 3 is a block diagram showing an embodiment of the present invention. , FIGS. 4a, b, and c are diagrams showing the state of wave transmission and reception by the device of the present invention and a flowchart of its operation. FIGS. Figure 6 is a block diagram showing a modification of the present invention; Figures 7a, b, and c are diagrams showing waveforms and their summed and synthesized waveforms; Figures 7a, b, and c show the ultrasonic wave transmitting position constant and sector scanning; FIG. 3 is a diagram for explaining an example in which only the information is sequentially changed. 1...Test object, 31...Probe, 31 ₁ to 31 _o ...
Vibrator, 32... Transmitter group, 33... Wave transmission direction setting device, 34... Delay time controller, 35, 35 ₁ to 35 _o
...Receiver, 36, 36 ₁ to 36 _o ... Adder.

Claims (1)

[Claims] 1. An array-type probe with a large number of transducers arranged in parallel to transmit and receive ultrasonic waves, and by controlling the phase of the multiple transducers of this probe, the ultrasonic beam is sequentially directed in multiple directions toward the object to be inspected. A device for transmitting waves and an arbitrary one of the vibrators are selected, and this vibrator is used for receiving waves, and each ultrasonic beam sequentially transmitted in the multiple directions is transmitted to the object to be inspected. It is characterized by comprising a device that receives the reflected waves without phase control using the wave receiving transducer, adds and synthesizes the received signals mutually, and provides signal processing for flaw detection. Ultrasonic flaw detection equipment.