JPS6228869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic scanning ultrasonic flaw detection method, and more particularly to an ultrasonic flaw detection method suitable for depthwise flaw detection inside a subject.

Conventionally, when detecting defects that exist perpendicular to the surface of the specimen, the angle probe is moved on the surface of the specimen and the depth is estimated from the distance of movement, or a moving gate is installed and the probe The depth can be estimated by correcting the gate position based on the distance traveled by the probe, or alternatively, a fixed gate and a triangular shoe can be installed, and the depth can be estimated by moving the probe on the shoe. It was done.

However, all of these methods involve moving the probe mechanically, and when performing remote automatic flaw detection using these methods, the detection unit becomes large and
There were drawbacks such as poor inspection efficiency.

An object of the present invention is to provide an electronic scanning ultrasonic flaw detection method that is not limited by the structure of the test object and can easily and accurately evaluate crack defects that occur in the depth direction of the test object. It's about doing.

A feature of the present invention is that an ultrasonic wave transmitting transducer and a wave receiving transducer are installed on the surface of a subject via the ultrasonic medium, using an ultrasonic medium having an inclined surface. are arranged facing each other, the beam area of the transmitting transducer and the beam area of the receiving transducer are made to intersect, and both transducers are excited in a predetermined order to scan the intersecting area in the depth direction. This is where I decided to do it.

Examples of the present invention will be described in detail.

FIGS. 1 and 2 are explanatory diagrams of the electronic scanning ultrasonic flaw detection method that forms the premise of the present invention. In the same figure,
Reference numeral 10 denotes ultrasonic transducers, and n ultrasonic transducers #1 to #n are arranged. 11 and 17 are ultrasound media, and 12 is a subject.

Now, in FIG. 1, when a group of k transducers (k<n) is excited with a time difference such that the longitudinal mode wavefront becomes AB, the ultrasonic beam propagates in 13 directions. This excited group of oscillators is sequentially moved by the arrow 14.
When the ultrasonic beam 13 on the YY' axis moves in the direction 16, the ultrasonic beam 13 moves in the direction 16.

The case of Fig. 2 is the same as Fig. 1, and Y-
The ultrasound beam 18 on the Y' axis moves in the direction 20.

In these figures, the ultrasonic media 11 and 17 are used to enable ultrasonic flaw detection of the surface layer of the object 12, to prevent mechanical damage to the transducer, and to suit the shape of the object. It is possible to process the contact surface by
By being able to arbitrarily select the incident angle of the ultrasonic waves,
This is essential for performing ultrasonic flaw detection on industrial materials.

The ultrasonic medium may be made of metal, non-metal, liquid, etc., but acrylic resin is often used at room temperature.

FIGS. 3 and 4 are diagrams showing the ultrasonic beam path in terms of geometric shapes.

In the case of Figure 3, formula (1) is used, and in the case of Figure 4, formula (2) is used.
The formula becomes

However, l _R : Ultrasonic beam path (points e, f,
g) d: Thickness of the ultrasonic medium θ _i : Incident angle of the ultrasonic beam entering the object from the ultrasonic medium x: Distance from the defect to the beam incidence point θ _r : Refraction angle of the ultrasonic beam However, l _T : Ultrasonic beam path (points e, f,
(distance between g) b: Length of the ultrasonic medium from the defect Generally, the sound speeds are different between the mediums 11 and 17 and the medium 12, and refraction occurs at the interface, so the path of the ultrasonic beam becomes a polygonal line.

FIG. 5 and FIG. 6 are diagrams showing the relationship of focusing of ultrasonic beams. The ultrasound beam is refracted as shown by the solid line, but if it is corrected by the speed of sound in the medium at the mouth of the subject, the transducer position can be assumed to be on the extension of the ultrasound beam path in the subject, as shown by the dotted line in the figure. I can do it.

In order to focus the ultrasonic beam on the Y-Y' axis, instead of the plane A'-B', the cylindrical surface C-
It is only necessary to consider D, and it is sufficient to sequentially excite each vibrator with a time difference corresponding to the difference between the A'-B' plane and the CD plane.

The time difference in the case of FIG. 5 is expressed by the following equation.

However, Δt _Rj : Phase time of the transducer separated by a _j from the beam center line Δl _Rj : Distance between the plane A'-B' and the curved surface C-D of the transducer separated by a _j from the beam center line c ₂ : Speed of sound in the object 12 a _j : Distance from the beam center on the transducer surface c ₁ : Speed of sound in the ultrasonic medium 11 The time difference in the case of FIG. 6 is expressed by the following equation.

However, Δt _Tj : Phase time of the transducer separated by a _j from the beam center line Δl _Tj : Distance between the plane A'-B' and the curved surface C-D of the transducer separated by a _j from the beam center line The second item in equation 3) is the time difference for tilting the ultrasonic beam by θ _i , and when a _j is on the B side, it is (+), and when it is on the A side, it is (−).

In the case of equation (4), since the ultrasonic medium 17 has a triangular shape, there is no need for a delay time corresponding to the second item in equation (3), which simplifies the circuit and makes calculations easier. It has advantages.

In the above explanation, when longitudinal ultrasound is used inside the subject, the longitudinal sound velocity may be used as C ₂ .
On the other hand, when using a transverse wave ultrasound, the delay time may be set using the transverse sound velocity as _C2 .

In this way, when the ultrasonic beam is sent out, it becomes as shown in FIGS. 7 and 8, and the focusing area of the ultrasonic beam is sequentially Y-
It can be moved in the direction above the Y′ axis. However, in this case, the focused beam region is in the depth direction.

FIG. 9 is a diagram showing a method for measuring the crack depth of a defect by the electronic scanning ultrasonic flaw detection method according to the present invention. As shown in the figure, ultrasonic media 17 and 17' are placed on both sides of the sound insulating plate 24, and an ultrasonic beam 26 is sent out from k ultrasonic transducers of the ultrasonic medium on the 17 side. In the focusing region 27, the ultrasound beam is scattered, and a portion of it is scattered like 28 ultrasound beams.
The signals are received by k ultrasonic transducers from #1 on the 7' side. However, when the excitation position of the ultrasonic transducer 10 is moved from k including #1 to k including #i, the ultrasonic beam becomes 29, and the defect 25
corresponds to Defect 25 blocks ultrasonic waves, so 1
The k transducers including #i on the 7' side cannot receive ultrasonic waves. In this way, the ultrasonic transducer 10,
When the excitation and reception positions of 10' are moved from #1 to #n, the scattered echoes disappear midway, but
The defect depth can be determined from the position where this echo disappears.

Since this method uses a linear scanning method to scan the ultrasonic beam, there is no loss due to the scanning angle, which is a problem with other fan-shaped scanning methods, and it has the great advantage of being able to scan with uniform intensity in the depth direction of the defect. be.

FIG. 10 is a block diagram of a circuit for performing electronic scanning ultrasonic flaw detection. A main control section 31 generates a synchronization signal 39, a transducer selection command signal 40, and a focus area command signal 41. The wave transmission control unit 32 receives these signals, determines the order of wave transmission, and transmits the order to the wave transmission drive unit 33. The wave transmission drive section 33 is connected to each vibrator 10.
A pulsed voltage is applied to.

On the other hand, the ultrasonic energy received by each transducer 10 is amplified by the receiving amplifier 34, and the receiving detector 3
The signals are added and detected in step 5 and sent to the display section 36.

A delay circuit 37 generates a delay time corresponding to the reciprocating propagation time of the ultrasonic media 11 and 17, and delays the synchronization signal from the main control circuit and sends it to the sweep signal generation circuit 38. The sweep signal generation circuit sends out X and Y signals according to the path of the ultrasonic waves, and displays a defect image on the display section.

11, 12, and 13 are time charts of the circuit block diagram for the electronic scanning ultrasonic flaw detection method shown in FIG. 10. In these figures, numeral 39 is a synchronization signal, which generates S-series and T-series signals. S indicates set and T indicates trigger. First, considering the time chart during wave transmission shown in FIG. 11, in _S1 , a transducer selection command 40 is generated, and, for example, transducers #1 to #k are selected. Further, a focusing area command 41 is generated to set the phase difference of the vibrators #1 to #k.

Next, when the transducers are excited according to the settings of S ₁ at T ₁ , the transducers #1 to #k are each excited with a phase difference of Δt _Tj , and the ultrasonic waves are focused at the depth D ₁ .

S ₂ is the setting for T ₂ , #2 to #(k−
The transducer of 1) is selected and the focusing region is set at depth D ₂ . Therefore, at T ₂ , #2 to #(k
-1) The vibrator is excited and the ultrasonic waves are focused at depth _D2 .

As mentioned above, the k-th S _k , T _k , the i-th S
_i , T _i , (n-k)th S _(ok) , and T _(ok) , the oscillators #~k~#(2k-1),
It is excited from #i to #(i+k-1) and from #(n-k) to #n, and the depth of the focusing region moves from D _k to D _i to D _(ok) .

FIG. 12 is a time chart during wave reception. In the case of wave reception, the analog delay time of the transducers # ₁ to #k is set at S1, and reception is started at _T1 . 42 in the figure is an analog delay element, the length of which corresponds to, for example, Δt _Tj . _S2 is for making the following settings, setting the analog delay times of #2 to #(k-1), and starting reception at _T2 . In this way, S _k , T _k , ... S _i , T _i , ... S _(ok) , T _(o-
k) and reception while sequentially switching the analog delay.

FIG. 13 is a time chart when the flaw detection results are displayed as images on the monitor. 39 is a synchronization signal, and 43 is a delay pulse corresponding to the round trip time in the ultrasonic medium, which is generated, for example, with a 2(b-x)/c ₁ sinθ _i time delay from the synchronization signal, and is displayed on the X axis for display. A signal 44 as well as a Y-axis signal 45 are generated. The X-axis signal is biased in the amplitude direction.

FIG. 14 is a flowchart of the electronic scanning ultrasonic flaw detection method.

As described above, according to the present invention, it is possible to electronically focus or scan an ultrasonic beam on a desired position of a vertical crack defect near the surface of a test object, and to form and display a defect image at high speed. Therefore, great industrial benefits can be expected, such as miniaturization of the detection unit and improvement in inspection efficiency.

Although the present invention was made particularly targeting defects near the surface, its effects are remarkable in the scattered wave method.

Furthermore, although the present invention has been described with respect to rectangular and triangular ultrasonic media, the present invention does not limit the shape of the ultrasonic medium to this, and curves and broken lines are also included in the present invention.

In addition, the present invention also includes materials such as metals, non-metals, and liquids for the ultrasonic medium.

[Brief explanation of the drawing]

1 to 8 are diagrams for explaining the premise or principle of the present invention.
The figure is an explanatory diagram of the electronic scanning ultrasonic flaw detection method (triangular ultrasonic medium), Figure 3 is a numerical relationship diagram of the ultrasonic beam path of the electronic scanning ultrasonic flaw detection method (rectangular ultrasonic medium), and Figure 4 The figure is a numerical relationship diagram of the ultrasonic beam path length for electronic scanning ultrasonic flaw detection (triangular ultrasonic medium), and Figure 5 is an explanatory diagram of the focusing state of the ultrasonic beam for electronic scanning ultrasonic flaw detection (rectangular ultrasonic medium). sound wave medium),
Figure 6 is an explanatory diagram of the focusing state of the ultrasonic beam in the electronic scanning ultrasonic flaw detection method (triangular ultrasonic medium);
The figure is an explanatory diagram of the movement of the ultrasonic beam focusing area in the electronic scanning ultrasonic flaw detection method (rectangular ultrasonic medium), and Figure 8 is an explanatory diagram of the movement of the ultrasonic beam focusing area in the electronic scanning ultrasonic flaw detection method (triangular shape (ultrasonic medium).
Figures 9 to 14 are diagrams explaining one embodiment of the present invention, in which Figure 9 is an explanatory diagram of crack depth evaluation using electronic scanning ultrasonic flaw detection, and Figure 10 is an illustration of crack depth evaluation using electronic scanning ultrasonic flaw detection. Fig. 11 is a time chart when transmitting waves for electronic scanning ultrasonic flaw detection, Fig. 12 is a time chart when receiving waves for electronic scanning ultrasonic flaw detection, and Fig. 13 is a time chart for electronic scanning ultrasonic flaw detection. FIG. 14 is a time chart when displaying an image of the scanning ultrasonic flaw detection method. FIG. 14 is a flow chart of the electronic scanning ultrasonic flaw detection method. 10... Ultrasonic vibrator, 13, 15, 18, 1
9, 26, 28, 29... Ultrasonic beam, 12... Subject, 11, 17, 17'... Ultrasonic medium, 21,
22, 23, 27, 30... focus area, 37... delay circuit.

Claims (1)

[Claims] 1. In an electronic scanning ultrasonic flaw detection method in which a plurality of ultrasonic transducers for transmitting and receiving waves are arranged and sequentially excited to detect flaws inside a subject, A transducer for transmitting a wave and a transducer for receiving a wave are respectively installed on the surface of the object with an ultrasonic medium having a slope inclined in a direction in which both transducers face each other, and the transducer for transmitting a wave is placed on the surface of the object. An electronic scanning ultrasonic flaw detection method, characterized in that a beam region and a beam region of a receiving transducer intersect, and both of the transducers are sequentially excited to scan the intersecting region in the depth direction of the object. 2. The electronic scanning ultrasound according to claim 1, characterized in that the beam area of the transmitting transducer and the beam area of the receiving transducer are focused and intersect at both focusing areas. Flaw detection method.