JPH09229918A - Method and device for ultrasonic flaw detection with array type ultrasonic probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid falling of sound field intensity at the border of sound field formed by adjoining ultrasonic wave probs. SOLUTION: Multiple ultrasonic probes E (E1 -Ej ) arrayed in a straight line are used for each set comprising a specified numbers of succeeding ultrasonic probes E1 -Ej , and, at least one super ultrasonic probes Ei -Ej among ultrasonic probes Ei -Ei+j-1 which belong to adjoining sets is made to be duplicated. Then, the above stated sets are sequentially switched in the direction of array, and the width of ultrasonic probe group belonging to a set is made larger than the feeding pitch at the switching, and, the feeding pitch at the switching is made equal or smaller than the effective beam width of ultrasonic radiated by one set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method and an ultrasonic flaw detection device used in an automatic ultrasonic flaw detection system for an object such as a steel pipe.

[0002]

2. Description of the Related Art Conventionally, there is an ultrasonic automatic flaw detection system of this kind as shown in FIG. 11. In this system, a steel pipe moving in the axial direction (arrow) while rotating is moved in the axial direction. The four ultrasonic probes 2 (2 ₁ , 2 ₂ , 2 ₃ , 2 ₄ ) arranged in one line are used for flaw detection. Here, the region to be flaw-detected by the ultrasonic probe 2 ₂ is a band-shaped spiral region with a mesh pattern, and by arranging four ultrasonic probes 2 in the axial direction, the steel pipe It is possible to detect the entire surface of the. As shown in FIG. 11B, the ultrasonic waves transmitted from each ultrasonic probe 2 mainly propagate in the pipe wall 1 in the circumferential direction, and are mainly generated in the cracks running in the pipe axis direction of the pipe wall 1. Such a defect is reflected, and the defect is detected by receiving the reflected wave with the ultrasonic probe.

Further, in order to detect defects such as cracks running in the circumferential direction of the pipe wall 1 with high sensitivity, as shown in FIG. 12, a plurality of ultrasonic probes 3 (3 ₁ , 3) are used. ₂ , 3 ₃ ,
3 ₄ ) is installed by inclining in a plane including the tube axis in advance, and ultrasonic waves are propagated in the tube axis direction of the tube wall 1. Therefore, in order to propagate ultrasonic waves in both the circumferential direction and the axial direction,
A plurality of ultrasonic probes 2 for circumferential propagation shown in FIG.
A plurality of ultrasonic probes 3 for axial propagation 2 are separately prepared for each purpose.

[0004]

However, in such an ultrasonic flaw detection method and apparatus, the sound field strength decreases at the boundary of the sound fields formed by the adjacent ultrasonic probes, and the detection sensitivity decreases. There is a problem. That is, although FIG. 13 schematically shows the sound field strength at a position about 30 mm away from the surface of the ultrasonic probe 2, for example, the width of the ultrasonic probe is 15 mm.
mm, it is 10 dB with respect to the sound field intensity formed in the central portion of the ultrasonic probe at the boundary between the adjacent ultrasonic probes.
It is getting lower near.

Generally, in a short-range sound field formed near an ultrasonic probe, the effective beam width (the level is 3 dB with respect to the peak value of the sound field intensity obtained in the central portion of the ultrasonic probe).
Since the width (defined as the width until it decreases) is smaller than the width of one ultrasonic probe, the conventional method inevitably lowers the sound field strength at the boundary between adjacent ultrasonic probes. As a result, there is a problem that the flaw detection area corresponding to the boundary between the adjacent ultrasonic probes falls out in a spiral shape, and a sensor is additionally installed in the area corresponding to the boundary.

Further, in the conventional method, in order to perform flaw detection in both the circumferential direction and the axial direction, a plurality of ultrasonic probes for circumferential propagation and a plurality of ultrasonic probes for axial propagation. Since the child must be installed in each of the narrow spaces, the installation is time-consuming, and the number of parts is increased, so that the cost is increased. The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method that do not cause a decrease in sound field strength as in the related art.

Another object of the present invention is to provide an ultrasonic flaw detector and an ultrasonic flaw detection method capable of performing flaw detection in both the circumferential direction and the axial direction by using the same array type ultrasonic probe. is there.

[0008]

In order to achieve the above object, in the ultrasonic flaw detection method according to claim 1 of the present invention, a plurality of ultrasonic transducers arranged in a straight line are arranged in a fixed number. It is used for each set composed of continuous ultrasonic probes, and one or more ultrasonic probes among the ultrasonic probes belonging to an arbitrary set and the adjacent set must be duplicated. The groups are sequentially switched along the arrangement direction so that the width of the ultrasonic probe group belonging to one group is larger than the switching feed pitch, and the switching feed pitch is set by one group. It is characterized in that it is equal to or slightly smaller than the effective beam width of the ultrasonic waves to be irradiated.

Further, in the ultrasonic flaw detection method according to claim 2 of the present invention, in the ultrasonic flaw detection method according to claim 1, when the ultrasonic probe is used for each set, the ultrasonic probe is positioned at both ends of the set. It is characterized in that weighting is performed to reduce the transmission sensitivity or the reception sensitivity of at least one ultrasonic probe. Further, in the ultrasonic flaw detection method according to claim 3 of the present invention,
Alternatively, when the ultrasonic probes are used for each group, the excitation timing is delayed along the array direction of the ultrasonic probes belonging to the group, and the ultrasonic probes are arranged in the array direction. A method of transmitting and receiving an ultrasonic beam in a direction deviating from the front direction of the ultrasonic probe by delaying the reception timing in sequence along with a method of simultaneously exciting the ultrasonic probes belonging to the set. And a method of transmitting and receiving an ultrasonic beam in the front direction of the ultrasonic probe at the same time with the reception timings, and the method is appropriately selected and performed.

Further, in the ultrasonic flaw detection method according to claim 4 of the present invention, in the method according to claim 1 or 2,
When the ultrasonic probes are used for each group, the ultrasonic probes of the same group are used twice in succession, and the ultrasonic probes belonging to the group are sequentially arranged along the array direction. A method of transmitting and receiving an ultrasonic beam in a direction deviated by a predetermined angle from the front direction of the ultrasonic probe, in which the excitation timing is delayed and the reception timing is sequentially delayed along the array direction. Both the method of transmitting and receiving the ultrasonic beam in the front direction of the ultrasonic probe at the same time by simultaneously exciting the ultrasonic probes belonging to The feature is that it is performed continuously.

Further, in the ultrasonic flaw detection method according to claim 5 of the present invention, in the method according to claim 1 or 2,
When the ultrasonic probes are used for each set, the excitation timing is sequentially delayed along the arrangement direction of the ultrasonic probes belonging to the set so that the excitation pitch p is p = λ / sin θ ₀ (Λ is the wavelength of the ultrasonic wave) is satisfied, and both the ultrasonic beam in the direction θ _{0 that} is deviated from the front direction of the ultrasonic probe by a predetermined angle and the ultrasonic beam in the front direction of the ultrasonic probe are The signals are transmitted at the same time, and the reception timings are sequentially delayed by the pitch p along the array direction of the ultrasonic probes belonging to the set so that the ultrasonic wave in the direction θ ₀ deviated from the front direction of the ultrasonic probes by a predetermined angle Both the ultrasonic beam and the ultrasonic beam in the front direction of the ultrasonic probe are received, and the reception timings of the ultrasonic probes belonging to the group are all set at the same time to detect the ultrasonic wave in the front direction of the ultrasonic probe. Receiving a sound wave beam.

In the ultrasonic flaw detector according to claim 6 of the present invention, a plurality of ultrasonic probes arranged in a straight line and a transmitter for exciting the plurality of ultrasonic probes. A receiver for receiving signals from the plurality of ultrasonic probes, a switch for switching connections between the plurality of ultrasonic probes and the transmitter, and the plurality of ultrasonic probes and the receiver And a switch for connecting the plurality of ultrasonic probes to the transmitter and the receiver for each set constituted by a constant number of continuous ultrasonic probes, And ultrasonic probes belonging to a group adjacent to the ultrasonic probe belonging to one group by sequentially switching the groups along the arrangement direction so that at least one ultrasonic probe overlaps. Make sure that the width of the tentacle group is larger than the feed pitch for switching. And equal to or ultrasound effective beam width that is irradiated with the feed pitch of said switched by one group performs switching as slightly below, characterized in that.

In the ultrasonic flaw detector according to claim 7 of the present invention, in the transmitter or the receiver according to claim 6, transmission of one or more ultrasonic probes located at both ends of the set. A feature is that weighting is performed to reduce sensitivity or reception sensitivity. In the ultrasonic flaw detector according to claim 8 of the present invention, the ultrasonic flaw detector according to claim 6 or 7,
Each of the transmitter and the receiver is composed of a plurality of transmitters and a plurality of receivers, and the switching device includes the plurality of ultrasonic probes for each of the sets, the plurality of transmitters and the plurality of receivers. When connecting to the receiver, the ultrasonic probe belonging to the set is connected to the transmitter so as to delay the excitation timing in sequence along the array direction, and the ultrasonic probes are sequentially received along the array direction. In the case of connecting to the receiver so as to delay the timing, and in the case of connecting to the transmitter so as to simultaneously excite the ultrasonic probes belonging to the group and at the same time to connect to the receiver so as to make the reception timing at the same time. One of the cases is appropriately selected and connected.

In the ultrasonic flaw detector according to claim 9 of the present invention, in the ultrasonic flaw detector according to claim 6 or 7, the transmitter and the receiver are respectively composed of a plurality of transmitters and a plurality of receivers. , The switching device, when connecting the plurality of ultrasonic probes to the plurality of transmitters and the plurality of receivers for each set, along the array direction of the ultrasonic probes belonging to the set. Of the ultrasonic probe belonging to the group and the case of connecting to the transmitter so as to sequentially delay the excitation timing and the receiver so as to sequentially delay the reception timing along the array direction. Connect to the transmitter so as to excite the child at the same time and to connect to the receiver so that the timing of reception is the same. Featuring That.

In the ultrasonic flaw detector according to claim 10 of the present invention, in the ultrasonic flaw detector according to claim 6 or 7, the transmitter and the receiver are respectively composed of a plurality of transmitters and a plurality of receivers. And the switching device is
When connecting the plurality of ultrasonic probes to the plurality of transmitters and the plurality of receivers for each of the sets, excitation is sequentially performed along the array direction of the ultrasonic probes belonging to the set. By delaying the timing and connecting the transmitter so that the excitation pitch p satisfies p = λ / sin θ ₀ (λ is the wavelength of the ultrasonic wave), a direction θ ₀ deviated from the front direction of the ultrasonic probe by a predetermined angle Both the ultrasonic beam of the ultrasonic probe and the ultrasonic beam of the front direction of the ultrasonic probe are transmitted at the same time, and the reception timing is sequentially delayed by the pitch p along the arrangement direction of the ultrasonic probes belonging to the set. To connect the first receiver group of the plurality of receivers so that the ultrasonic beam in the direction θ ₀ deviated by a predetermined angle from the front direction of the ultrasonic probe and the ultrasonic wave in the front direction of the ultrasonic probe. Both the ultrasonic beams are received, and the reception timing of the ultrasonic probes belonging to the group is set. Base and wherein the to receive the plurality of second connected to the receiver unit in the front direction of the ultrasonic probe ultrasonic beams in the receiver so that at the same time.

In the invention according to claim 1 or 6, in order to make the feed pitch for switching the set equal to or slightly smaller than the effective beam width of the ultrasonic waves emitted by one set, the super pitch belonging to a certain set is set. The sound field strength is less likely to decrease at the boundaries of the regions to be flaw-detected by the ultrasonic probe and the ultrasonic probes belonging to the adjacent set, so that the defect detection performance can be guaranteed.

According to the invention of claim 2 or 7,
By performing weighting, the sound field intensity of the ultrasonic beam obtained by a certain number of ultrasonic probes belonging to one set can be made flat within the effective beam width range. Further, in the inventions according to claims 3, 4 or 8 and 9, the excitation timing is sequentially delayed along the arrangement direction of the ultrasonic probes belonging to one set, and the ultrasonic probes are sequentially arranged along the arrangement direction. By delaying the reception timing, ultrasonic waves can be propagated in the direction deviated by a predetermined angle from the front of the ultrasonic probe, and the ultrasonic waves incident from the direction deviated by a predetermined angle can be efficiently transmitted. Since it can be received well, it can be used for axial propagation of a steel pipe or the like. Further, by simultaneously exciting the ultrasonic probes belonging to one set and simultaneously receiving the signals, the ultrasonic waves propagating in the front direction of the ultrasonic probes are used to determine the incident angle in the circumferential direction. It can be used for circumferential propagation of a steel pipe or the like. Therefore, by appropriately selecting these, flaw detection in two directions can be performed by one array type ultrasonic probe.

Further, in the invention according to claim 5 or 10, both the ultrasonic beam in the direction deviated by a predetermined angle from the front direction of the ultrasonic probe and the ultrasonic beam in the front direction of the ultrasonic probe at a time. Since it is possible to transmit and receive, it is possible to detect flaws in two directions with one array type ultrasonic probe.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing an ultrasonic flaw detection method using the array type ultrasonic probe of the present invention or an ultrasonic flaw detection apparatus used in the ultrasonic flaw detection method of the present invention. Is equipped with an array type ultrasonic probe and its transmitting / receiving circuit.

As shown in FIG. 1, the ultrasonic flaw detector of the present example has an elongated rectangular ultrasonic probe E having a very small width.
_A large number of ₁ , ₁ , E ₂ , ..., E _n are arrayed, and are used by a switcher 18 for each fixed number (j) of groups, as will be described later. Each set of each ultrasonic probe is connected to the transmission / reception circuit 10. The transmission / reception circuit 10 includes a main controller 12, a transmitter 14 that transmits a transmission pulse in response to a trigger signal from the main controller 12, and a receiver 16 that receives and amplifies a reception signal from the ultrasonic probe E. A switching device 18 that performs a switching operation according to a control signal from the main controller 12.
And.

In the ultrasonic flaw detector constructed as described above, the switching device 18 includes a plurality of ultrasonic probes E ₁ ,
Connection between the transmitter 14 and the set of ultrasonic probes and the set of the receiver 16 and the ultrasonic probe so that E ₂ , ..., E _n are used for each fixed number (j) of sets Switch connection with. At this time, for example, ₁ constituted by the ultrasonic probes E _{1 to} E _j
One set adjacent to one set is composed of the ultrasonic probes E _{i to} E _{i + j-1} so that at least one ultrasonic probe E _{i to} E at the boundary of the sets is surely included. Switch so that _j is used twice.

FIG. 2 shows the concrete switching of the ultrasonic probe groups and the state of the sound field formed by each group, and the numbers written in the elongated boxes are the ultrasonic waves used. The number of the sound wave probe is shown. FIG. 2 shows a case in which 504 ultrasonic probes having a width of 0.22 mm are arranged on a straight line. In order to obtain an effective beam width of about 15 mm described in the conventional example, One set is composed of 96 continuous ultrasonic probes so that the width W of the ultrasonic probe group belonging to the set is about 20 mm. Then, it is composed of 96 continuous ultrasonic probes so that the width W of the ultrasonic probe group of the adjacent set is also about 20 mm, and the switching feed pitch, that is, the feed pitch of transmission and reception is effective. To be about 15 mm, which is equal to or slightly smaller than the beam width,
The width of the ultrasonic probes used in duplicate is about 5 mm (that is, 28 ultrasonic probes (number 69 to 96) are used in duplicate). Further, the width of the ultrasonic probe group used next time is 20 mm (96 pieces), and the width of the overlapping ultrasonic probe is 5 mm (No. 137 to 164), and this is repeated.

FIG. 3 shows a sound field obtained by transmitting and receiving a set of 96 ultrasonic probes in the example of FIG. 2 at a distance of about 30 mm from the surface of the ultrasonic probe. An example of strength calculation will be shown. In this case, a wide effective beam width of 18 mm can be obtained. Therefore, if the feed pitch is 15 mm, it is possible to make the effective beam width slightly larger than the feed pitch. Therefore, the boundary between the regions to be flaw-detected by the ultrasonic probes belonging to a certain set and its adjacent set is increased. In, the decrease in the sound field strength is reduced, and thus the defect detection performance can be guaranteed.

Next, a second embodiment of the present invention will be described.
You. The result of Fig. 3 shown in the previous example is, in itself, sufficient performance.
However, the sound field strength at both ends is slightly strong and overshoots.
And the flatness of the sound field is slightly impaired.
You. Therefore, in this example, the two ends of one ultrasonic probe group are
Weighting that reduces the receiving sensitivity of several ultrasonic probes
To obtain a flat sound field distribution
It is. A schematic block diagram of the ultrasonic flaw detector used in this example.
Figure 4 shows the diagram. The device of FIG. 4 is used once
A number of different gains corresponding to (ie a set of) ultrasound probes
Receiver 16 that amplifies with₁・ ・ ・ 16_jEquipped with each
Receiver 16 ₁・ ・ ・ 16_jIs the signal from each ultrasonic probe
Are amplified, and their outputs are added by the adder 20.
You. The same parts as those in FIG. 1 are designated by the same reference numerals.
You.

FIG. 5 shows an example of the weighting amount of the reception gain for one set of 96 ultrasonic probes, and FIG. 6 shows an example of calculation of the sound field strength obtained when using this weighting amount. . In FIG. 6, it can be seen that the effective beam width is close to 16 mm, the ripples appearing at both ends in FIG. 3 are small, and a very flat sound field distribution is obtained. In this example, the weighting is performed by the gain at the time of reception, but the present invention is not limited to this, and it is of course conceivable to weight the excitation amplitude at the time of transmission. In this case, instead of providing a plurality of receivers, a plurality of transmitters are provided corresponding to an ultrasonic probe used at one time, and several transmitters at both ends of one ultrasonic probe group are provided. Weighting may be performed to reduce the excitation amplitude of the ultrasonic probe.

Next, a third embodiment of the present invention will be described. In the previous example, the ultrasonic flaw detector suitable for propagating ultrasonic waves in the front direction of the ultrasonic probe was described,
In this example, not only that direction but also ultrasonic waves in a direction deviated by a predetermined angle from the front direction of the ultrasonic probe can be propagated, so that both the circumferential and axial flaw detection can be performed. It was done.

FIG. 7 shows a schematic block diagram of the ultrasonic flaw detector used in this example. In FIG. 7, 22 is a transmission timing controller, 14 ₁ , ... 14 ₈ are transmitters, 16 ₁ ,
... 16 ₈ is a receiver, 24 ₁ , ... 24 ₈ is a delay line disposed between the switch 18 and the receivers 16 ₁ , ... 16 ₈ and 26 ₁ , ... 26 ₈ is a bypass circuit that directly connects the switch 18 and the receivers 16 ₁ , ... 16 ₈ . In this example, the switching device 18 controls the transmission of a set of ultrasonic probes by the control signal from the main controller 12, and after each transmitter 14 excites two adjacent ultrasonic probes, two The contacts of the switch 18 are connected so that received signals from two adjacent ultrasonic probes are sent to each receiver 16 via each delay line 24 or each bypass circuit 26.

First, the case of propagating an ultrasonic wave in a direction deviating from the front direction of the ultrasonic probe by a predetermined angle will be described. The transmission timing controller 22 shifts a constant time interval τ by a plurality of transmitters 14 ₁ , 14 ₈ (sequentially delayed from 14 ₈ ) is used to control the transmission timing, and the excitation timing of the ultrasonic probe E is shifted by τ.

Now, with ultrasonic probes E ₁ to E ₁₆ , 1
Assuming that a set of ultrasonic probe groups is formed and the transmission and reception of this set is performed, the transmitter 14 ₁ has the ultrasonic probes E ₁ and E ₁ .
₂ , the transmitter 14 ₂ transmits ultrasonic probes E ₃ and E ₄ to the transmitter 1
4 ₈ excites the ultrasonic probes E ₁₅ and E ₁₆ , respectively. Therefore, after the ultrasonic probes E ₁₅ and E ₁₆ are first excited, the ultrasonic probes E ₁ and E ₂ are excited with a delay of 7τ. By doing so, the wavefront of the transmitted ultrasonic wave is formed so as to propagate in a direction deviating from the front direction of the ultrasonic probe E by a predetermined angle θ. At this time, the angle θ and the time delay τ have the following relationship.

[0030]

[Mathematical formula-see original document] C. [tau] = nd.sin [theta] where C is the speed of sound of the medium, d is the array pitch of the ultrasonic probes, and n is the number of ultrasonic probes E to be excited at the same time. n = 2. When receiving, the transmitter 14
₁ signal received by the excited ultrasonic probe E _1, E ₂ are input to the receiver 16 ₁ via the respective delay lines 24 _1, ultrasonic feeler which is excited by the transmitter 14 ₈ The signals received by the children E ₁₅ and E ₁₆ are input to the receiver 16 ₈ via each delay line 24 ₈ . Each of the delay lines 24 _{1 to} 24 ₈ has a delay time shifted by τ, and the delay time of 24 ₁ is 7τ longer than the delay amount of 24 ₈ . By adding the signals that have passed through the delay lines 24 _{1 to} 24 ₈ by the adder 20, it is possible to efficiently receive the ultrasonic waves that are incident from the direction deviated from the front direction of the ultrasonic probe E by θ. it can.

When the ultrasonic beam is tilted by an angle θ in the tube axis direction, the ultrasonic wave propagates along the tube wall 1 in the tube axis direction as shown in FIG. Defects such as cracks can be detected with high sensitivity. The above operation is performed by the following set, for example, ultrasonic probes E _{13 to} E.
₂₈ (ultrasonic probe E ₁₃ to ultrasonic probe E ₁₆ are used in duplicate), another ultrasonic beam can be irradiated, and irradiation by one set can be performed. If the effective beam width of the ultrasonic waves to be generated is equal to or slightly higher than the feed pitch for switching between groups, the sound field strength does not decrease much even in the flaw detection area corresponding to the boundary between adjacent groups, and the defect detection performance is improved. Guaranteed.

Further, when the ultrasonic wave is propagated in the front direction of the ultrasonic probe, the trigger signal from the transmission timing controller 22 is simultaneously sent to the plurality of transmitters 14 ₁ , ..., 14 ₈ . The ultrasonic probes E belonging to one set are simultaneously excited. At the time of reception, if the switching device 18 connects each ultrasonic probe E and the bypass circuits 26 ₁ ... 26 ₈ , the receiver 1 is passed through the bypass circuits 26 ₁ ... 26 _8.
By adding the signals input to 6 ₁ ... 16 ₈ with the adder 20, the ultrasonic waves incident from the front direction of the ultrasonic probe can be efficiently received, and the above-described example is described. It is possible to perform flaw detection in the circumferential direction.

As described above, since the propagation direction of ultrasonic waves can be appropriately selected, one array type ultrasonic wave can be obtained by alternately repeating for circumferential propagation at one time and axial propagation at the next opportunity. The probe can be used for both flaw detection in the circumferential direction and that in the axial direction. Furthermore, in order to detect flaws on the entire wall of the tube, the tube may be advanced while rotating, or the array ultrasonic probe may be rotated while advancing the tube.

As a method of alternately repeating the circumferential propagation and the axial propagation, for example, one set is used for the axial propagation and then the same set is used for the circumferential propagation ( This order may be either), and a method of successively using two times for adjacent axial pairs for axial propagation and circumferential propagation can be considered. Alternatively, after using for one set for axial propagation,
It is used for axial propagation to adjacent pairs in sequence, used for axial propagation to all pairs, then returned to the first pair and used for circumferential propagation. For example, a method used for circumferential propagation may be considered.

In FIG. 7, it is preferable to further weight the transmission sensitivity or the reception sensitivity as shown in FIG. Next, a fourth embodiment of the present invention will be described. In each of the above-described examples, the array pitch d of the ultrasonic probes is preferably such that the excitation pitch nd basically satisfies the relationship of nd <λ / 2 (λ is the wavelength of the ultrasonic wave), which satisfies this condition. By doing so, the phase of each ultrasonic wave output from the plurality of ultrasonic probes is the main direction (that is, the front direction of the ultrasonic probe, or the ultrasonic probe in the third embodiment). It can be configured to match only along a direction deviated from the front direction of the child or a front direction of the ultrasonic probe). In this example, by deliberately removing this condition, by propagating the ultrasonic beam in both the front direction of the ultrasonic probe and the direction deviated from the front direction by θ ₀ , the circumferential propagation and the axial propagation can be performed at once. It was made to be performed.

A schematic block diagram of the ultrasonic flaw detector used in this example is shown in FIG. In FIG. 9, the switch 18
The reception terminal, the receiver 16 ₁₁ via the delay line 24 ₁ ... 24 _8, ... 16 ₈₁ is connected to the (first receiver group) received without delay line 16 _12, ... 16 ₈₂ is connected. The outputs of the receivers 16 ₁₁ , ... 16 ₈₁ are added by the adder 20 ₁ , and the receivers 16 ₁₂ , ... 16 ₈₂ (second
The outputs of the receiver group) are added by the adder 20 ₂ .

Similarly to the third embodiment, the transmission timing controller 22 shifts by a constant time interval τ and a plurality of transmitters 14 ₁ , ..., 14 ₈ (delay in order from 14 ₈ ).
The transmission timing is controlled by sending a trigger signal to, and the excitation timing of the ultrasonic probe E is shifted by τ.
At this time, between τ and the array pitch d of the ultrasonic probes and the number n of the ultrasonic probes E to be simultaneously excited,

[0038]

If C · τ = nd · sin θ ₀ = λ is satisfied, the ultrasonic beam is propagated in the front direction of the ultrasonic probe and in the direction deviated from the front direction of the ultrasonic probe by θ ₀ . be able to. This will be described in detail with reference to FIG. 10. If one set of ultrasonic probes is considered to be a sound source schematically arranged at an nd array pitch, a wave f ₁ from the first sound source is generated.
And the wave f ₂ from the second source is

[0039]

Equation 3] is expressed as _{f 1 = sin {ωt-k} x · x-k y · (y-nd)} f 2 = sin {ω (t + τ) -k x · x-k y · y} It In order to propagate the ultrasonic wave in the direction deviated by θ ₀ from the front direction (x axis) of the ultrasonic probe, the phases of the respective waves must match on a line g perpendicular to the direction deviated by θ _0. From

[0040]

[Number 4] _{ωτ-k x · x 2 -k} y · y 2 = -k x · x 1 -k y · y 1 + k y · nd (1) (x 2 -x 1) / (y 2 -y ₁₎ = - tan .theta ₀ (2) _{where, k x = k · cosθ 0} , k y = k · sinθ 0 (3) holds, but these (2), transforming (1) with (3) ,

[0041]

Ωτ = k · sin θ ₀ · nd (4), and

[0042]

Since ω / k = C, the equation (4) is

[0043]

[Equation 7] becomes a _{Cτ = nd · sinθ 0 (5} ). Next, in order to propagate the ultrasonic wave in the front direction of the ultrasonic probe, the phases of the respective waves must match on a line parallel to the y-axis,

[0044]

[Equation 8] _{ωτ-k x · x 2 -k} y · y 2 = -k x · x 1 -k y · (y 1 -nd) + 2π (6) x 1 = x 2 (7) y 2 -y _{1 = -nd (8) k x} = k, k y = 0 (9) is satisfied. Here, 2π in the equation (6) indicates that there is a phase shift of 2π between f ₁ and f ₂ . From the above formula,

[0045]

Ωτ = 2π (10), and the equation (10) is

[0046]

(10) Cτ = λ (11) Therefore, τ and nd that satisfy the expressions (5) and (11) are as follows.

[0047]

Nd = λ / sin θ ₀ (12) When such an excitation pitch p = nd is selected, θ from the front direction of the ultrasonic probe and from the front direction of the ultrasonic probe.
_The ultrasonic beam can be propagated in the direction deviated by ₀ .

At the time of reception, the signals received by the ultrasonic probes E ₁ and E ₂ excited by the transmitter 14 ₁ are transmitted to the respective delay lines 24 ₁
Is input to the receiver 16 ₁₁ via the
_The signals received by the ultrasonic probes E ₁₅ and E ₁₆ excited by ₈ are input to the receiver 16 ₈₁ via each delay line 24 ₈ . Each of the delay lines 24 _{1 to} 24 ₈ has a delay time shifted by τ, and the delay time of 24 ₁ is 7τ compared to the delay amount of 24 _8.
Is increasing. That is, the receivers 16 _{11 to} 16 ₈₁ pitch the signals received by the ultrasonic probes E ₁ ... E ₁₆ at the pitch p =
nd will be received, and these receivers 16 _{11 to} 16
By adding the output from ₈₁ with the adder 20 ₁ , the ultrasonic waves entering from the direction deviating from the front direction of the ultrasonic probe E by θ ₀ and the ultrasonic probe E entering from the front direction. It can receive incoming ultrasonic waves. At the same time, the signals received by the ultrasonic probes E ₁ and E ₂ are not delayed and the receiver 16 ₁₂
The signals received by the ultrasonic probes E ₁₅ and E ₁₆ are input to the receiver 16 ₈₂ without delay. That is, the receivers 16 _{12 to} 16 ₈₂ receive the signals received by the ultrasonic probes E ₁ ... E ₁₆ at the pitch p = d, and the signals from these receivers 16 _{12 to} 16 ₈₂ are received. By adding the outputs with the adder 20 ₂ , only the ultrasonic waves incident from the front direction of the ultrasonic probe are received.

Therefore, the output of the adder 20 ₁ and the adder 20 ₂
By subtracting the output of 1 from the subtraction circuit 30, it is possible to discriminate only the ultrasonic waves that are incident from the direction deviating from the front direction of the ultrasonic probe E by θ ₀ . At this time, the adder 2
In the output of 0 _{1 and} the output of the adder 20 _2, an intensity difference occurs in the signals corresponding to the ultrasonic waves incident from the front direction of the same ultrasonic probe. Therefore, when subtracting the signals, It is advisable to multiply one by a previously determined coefficient and then subtract it. The subtraction circuit 30 can be configured by hardware or software.

In addition, in FIG. 9, it is also possible to weight the transmission sensitivity or the reception sensitivity as shown in FIG.

[0051]

As described above, according to claim 1 or 6,
According to the invention described, there is no decrease in the sound field intensity at the boundaries of the regions to be flaw-detected by the ultrasonic probes belonging to a certain set and the ultrasonic probes belonging to the adjacent set,
Therefore, it is possible to prevent the defect detection performance from deteriorating, and it is possible to halve the arrangement length of the sensor.

According to the invention of claim 2 or 7, the sound field intensity of the ultrasonic beam obtained by a certain number of ultrasonic probes belonging to one set is made flat within the effective beam width range. can do. In addition, claims 3, 4, 8
Further, according to the invention described in 9, the flaw can be detected in two directions by one array type ultrasonic probe, so that the number of parts can be reduced and the installation space can be afforded.

According to the invention of claim 5 or 10, the ultrasonic beam in a direction deviated by a predetermined angle from the front direction of the ultrasonic probe and the ultrasonic beam in the front direction of the ultrasonic probe at a time. Since both of the two can be transmitted and received, one array type ultrasonic probe can also be used for flaw detection in two directions.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an ultrasonic flaw detector according to a first embodiment of the present invention.

FIG. 2 is a specific explanatory diagram for switching the set of ultrasonic probes in FIG.

FIG. 3 is a calculation example of a sound field intensity obtained according to the first embodiment.

FIG. 4 is a schematic block diagram showing an ultrasonic flaw detector according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an example of a weighting amount of a reception gain in the second embodiment.

FIG. 6 is an example of calculation of sound field intensity obtained according to the second embodiment.

FIG. 7 is a schematic block diagram showing an ultrasonic flaw detector according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram showing ultrasonic wave propagation according to the third embodiment of the present invention.

FIG. 9 is a schematic block diagram showing an ultrasonic flaw detector according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing ultrasonic wave propagation in the fourth embodiment of the present invention.

11A is a perspective view showing an ultrasonic probe of a conventional ultrasonic flaw detector, and FIG. 11B is a sectional view showing the propagation of the ultrasonic wave.

FIG. 12 is an explanatory view showing a conventional ultrasonic probe for axial propagation.

FIG. 13 is about 30 degrees from the surface of the ultrasonic probe in FIG.
This is a simulated representation of the sound field strength at a place separated by mm.

[Explanation of symbols]

E (E _i ) Ultrasonic probe E _i1 First receiver group E _i2 Second receiver group 14 (14 _i ) Transmitter 16 (16 _i ) Receiver 18 Switcher 24 (24 _i ) Delay line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetoshi Hyodo 4-53-3 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd.

Claims (10)

[Claims] 1. A plurality of ultrasonic probes arranged in a straight line are used for each set constituted by a fixed number of continuous ultrasonic probes, and an arbitrary set and its adjacent set are used. The ultrasonic probe groups belonging to one set have widths that are sequentially changed along the arrangement direction so that at least one ultrasonic probe among the ultrasonic probes belonging to the set is overlapped. An arrangement form characterized in that it is set to be larger than the switching feed pitch, and is set to be equal to or slightly below the effective beam width of the ultrasonic waves irradiated by one set. Ultrasonic flaw detection method using an ultrasonic probe. 2. When the ultrasonic probes are used for each set, weighting is performed to reduce the transmission sensitivity or the reception sensitivity of one or more ultrasonic probes located at both ends of the set. The ultrasonic flaw detection method according to claim 1. 3. When the ultrasonic probes are used for each group, the excitation timing is delayed in sequence along the array direction of the ultrasonic probes belonging to the group, and the ultrasonic probes are arrayed along the array direction. A method of transmitting and receiving an ultrasonic beam in a direction deviating from the front direction of the ultrasonic probe by delaying the reception timing in sequence, and simultaneously exciting the ultrasonic probes belonging to the group 3. A method of transmitting / receiving an ultrasonic beam in the front direction of an ultrasonic probe at the same time of reception, and a method of appropriately selecting one of the methods and performing the method. Ultrasonic flaw detection method. 4. The ultrasonic probes of the same set are used twice consecutively when the ultrasonic probes are used for each set, and the ultrasonic probes belonging to the set are arranged in the array direction. Along with sequentially delaying the excitation timing along with delaying the reception timing along the array direction, an ultrasonic beam is transmitted and received in a direction deviated by a predetermined angle from the front direction of the ultrasonic probe. Method, and a method of simultaneously exciting the ultrasonic probes belonging to the set and simultaneously receiving them, and transmitting and receiving an ultrasonic beam in the front direction of the ultrasonic probe. The ultrasonic flaw detection method according to claim 1 or 2, wherein one of them is successively performed first. 5. When the ultrasonic probes are used for each set, the excitation timing is delayed in sequence along the arrangement direction of the ultrasonic probes belonging to the set so that the excitation pitch p is p. = Λ / si
nθ ₀ (λ is the wavelength of the ultrasonic wave) is satisfied, and the ultrasonic beam in the direction θ _{0 that} is deviated from the front direction of the ultrasonic probe by a predetermined angle and the ultrasonic beam in the front direction of the ultrasonic probe are Both of them are transmitted at the same time, and the reception timing is sequentially delayed by the pitch p along the arrangement direction of the ultrasonic probes belonging to the set, and the direction θ ₀ deviated from the front direction of the ultrasonic probes by a predetermined angle. Both the ultrasonic beam and the ultrasonic beam in the front direction of the ultrasonic probe are received, and the reception timings of the ultrasonic probes belonging to the group are all set at the same time, and the front direction of the ultrasonic probe is detected. 3. The ultrasonic beam of claim 1 is received.
Ultrasonic flaw detection method described. 6. A plurality of ultrasonic probes arranged in a straight line, a transmitter for exciting the plurality of ultrasonic probes, and receiving signals from the plurality of ultrasonic probes. A receiver, a switcher for switching the connection between the plurality of ultrasonic probes and the transmitter and the plurality of ultrasonic probes and the receiver, the switcher is a fixed number of continuous The plurality of ultrasonic probes are connected to the transmitter and the receiver for each set constituted by the ultrasonic probes, and an ultrasonic probe belonging to an arbitrary set and an adjacent set is surely connected. By sequentially switching the groups along the arrangement direction so that one or more ultrasonic probes overlap, the width of the ultrasonic probe group belonging to one group becomes larger than the feed pitch of the switching. And then
Also, the ultrasonic wave using the array type ultrasonic probe is characterized in that the switching is performed so that the switching pitch is equal to or slightly smaller than the effective beam width of the ultrasonic waves irradiated by one set. Flaw detector. 7. In the transmitter or the receiver,
The ultrasonic flaw detector according to claim 6, wherein weighting is performed to reduce the transmission sensitivity or the reception sensitivity of one or more ultrasonic probes located at both ends of the set. 8. The transmitter and the receiver each include a plurality of transmitters and a plurality of receivers, respectively, and the switcher transmits the plurality of ultrasonic probes to the plurality of transmitters for each set. When connected to the transmitter and the plurality of receivers, they are connected to the transmitter so as to delay the excitation timing in sequence along the array direction of the ultrasonic probes belonging to the set and along the array direction. In the case of connecting to the receiver so as to delay the reception timing in sequence, and in the case of connecting to the transmitter so as to simultaneously excite the ultrasonic probes belonging to the group and at the same time to make the reception timing coincide. The ultrasonic flaw detector according to claim 6 or 7, characterized in that either one of the case and the case is appropriately selected and connected. 9. The transmitter and the receiver each include a plurality of transmitters and a plurality of receivers, and the switcher transmits the plurality of ultrasonic probes to the plurality of transmitters for each set. When connected to the transmitter and the plurality of receivers, they are connected to the transmitter so as to delay the excitation timing in sequence along the array direction of the ultrasonic probes belonging to the set and along the array direction. In the case of connecting to the receiver so as to delay the reception timing in sequence, and in the case of connecting to the transmitter so as to simultaneously excite the ultrasonic probes belonging to the group and at the same time to make the reception timing coincide. 8. The ultrasonic flaw detector according to claim 6, wherein the ultrasonic flaw detection device is connected so that either one of the two cases is connected first and the other is connected first. 10. The transmitter and the receiver each include a plurality of transmitters and a plurality of receivers, and the switcher transmits the plurality of ultrasonic probes to the plurality of transmitters for each set. When connecting to the receiver and the plurality of receivers, the excitation timing is sequentially delayed along the arrangement direction of the ultrasonic probes belonging to the set, and the excitation pitch p is p =
Connect to the transmitter so that λ / sin θ ₀ (λ is the wavelength of the ultrasonic wave) is satisfied, and the ultrasonic beam in the direction θ _{0 that} is deviated by a predetermined angle from the front direction of the ultrasonic probe and the ultrasonic probe Both of the ultrasonic beams in the front direction are transmitted at the same time, and the reception timing among the plurality of receivers is sequentially delayed by the pitch p along the arrangement direction of the ultrasonic probes belonging to the set. 1
It is connected to a receiver group to receive both an ultrasonic beam in a direction θ ₀ deviated from the front direction of the ultrasonic probe by a predetermined angle and an ultrasonic beam in the front direction of the ultrasonic probe, and It is characterized in that it is connected to a second receiver group of a plurality of receivers so as to receive the ultrasonic beams in the front direction of the ultrasonic probe so that the reception timings of the ultrasonic probes to which they belong are all at the same time. The ultrasonic flaw detector according to claim 6 or 7.