JP2008139123A - Ultrasonic flaw detector and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detector using a phased-array ultrasonic flaw detection probe and a flaw detection method for performing flaw detection of high detection sensitivity, by preventing positional difference in focusing, between a transmission period and a reception period, where a transmitting position and a receiving position are shifted with a probe caused to scan. <P>SOLUTION: This ultrasonic flaw detector, using the phased-array ultrasonic flaw detection probe 1 made by linearly arranging a plurality of vibrators 3, is structured so that delay time is corrected in a transmission delay time calculation means 11 or a reception delay time calculation means 13, so that focus position on the receiving side corresponds to the focus position on the transmission side at an after-shift receiving position, when the probe 1 is shifted from a transmission point to a reception point by a scanning means 15 for shifting the probe 1 parallel to the surface of a tested body 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detection apparatus and method used for nondestructive inspection of containers and piping in various plants.

  2. Description of the Related Art Conventionally, an ultrasonic flaw detector is widely known as a non-destructive flaw detector used for inspecting a weld defect location or a defect in a material. With this ultrasonic flaw detector, the ultrasonic wave incident on the object to be inspected from the probe is reflected from there if there is a defect, so that the defect can be detected and returned after being incident. By measuring the time to come, the distance from the probe to the reflection source can be known.

  As shown in FIG. 15A, a normal ultrasonic flaw detection probe (probe) has a large transmission beam diameter d. Therefore, in automatic flaw detection that automatically moves the probe, transmission at the time of transmission is performed. The range a where the transmission cover area at the probe position A and the reception cover area at the probe position B at the time of reception wraps also increases, and subtle deviation in transmission / reception is a problem in reducing sensitivity. Don't be.

  On the other hand, in a phased array ultrasonic flaw detector and a general focus type probe, the ultrasonic beam diameter is small. Therefore, as shown in FIG. 15B, transmission at the probe position A during transmission is performed. The coverage area a of the reception cover area at the reception position B of the probe at the time of reception is small, and the transmission focus position P1 and the reception focus position P2 do not wrap and transmit / receive There is a problem that the deviation of the influence affects the detectability and lowers the sensitivity.

  In particular, when the thickness of the specimen is large, if the automatic flaw detection is performed by moving the probe at a constant speed, it takes a long time for the reflected wave to return at the end face of the thickness or the defective portion within the thickness. In the meantime, there has been a problem that the probe moves greatly and the sensitivity is lowered.

As an ultrasonic flaw detection technique using a phased array ultrasonic flaw detector, for example, Japanese Patent Application Laid-Open No. 60-236062 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2001-305115 (Patent Document 2) are known. .
In Patent Document 1, a time difference is given to each transducer in order to focus an ultrasonic beam at a predetermined position, and a received signal is not subjected to waveform addition or delay addition delayed by a predetermined time corresponding to the time of transmission. Simultaneous addition is shown.
Further, Patent Document 2 discloses a configuration including an arithmetic circuit that calculates a delay time for focusing an ultrasonic beam even when a flaw detection surface is not a flat surface but a curved surface having a complicated shape.
Japanese Patent Application Laid-Open No. 60-236062 (Gazette page 2, upper left column, line 14 to line 18, publication page 2, upper right column, line 19 to lower left column, line 3) JP 2001-305115 A

However, although the ultrasonic flaw detection apparatus described in Patent Document 1 has been shown to perform delay addition focusing and simultaneous addition at the time of reception, the focal position at the time of transmission and the time of reception by the movement accompanying the scanning of the probe are shown. This is not shown until the deviation of the focal position is prevented, and it is impossible to increase the inspection accuracy by preventing the decrease in sensitivity associated with the scanning of the probe.
Moreover, although Patent Document 2 shows that the delay time is corrected for a subject having a curved surface with a complicated shape, the shift of the focal position at the time of reception is prevented by the movement accompanying the scanning of the probe. However, it is not shown until it is done, and it is not possible to increase the inspection accuracy by preventing a decrease in sensitivity due to the scanning of the probe.

  Therefore, the present invention has been made in view of such a background, and particularly when the probe is scanned and the transmission position and the reception position move, the subject is particularly thick and the defect is deep. Provided are an ultrasonic flaw detection apparatus and a flaw detection method using a phased array ultrasonic flaw detection probe capable of performing a flaw detection with high detection sensitivity by preventing a shift in focus between transmission and reception when present. This is a problem.

  In order to solve the above-described problem, the invention described in claim 1 is directed to an ultrasonic flaw detection apparatus using a phased array ultrasonic flaw detector in which a plurality of vibrators are arranged in a line. A transmission delay time calculating means for calculating a required delay time for each transducer in order to simultaneously focus the sound beam on the transmitting side focal position in the subject, and so as to converge on the receiving side focal position in the subject. Receiving delay time calculating means for calculating a required delay time for each transducer during reception, and scanning means for moving the probe along the surface of the subject. The transmission delay time calculation means or the transmission side so that the reception-side focal position and the transmission-side focal position coincide with each other at the reception position after movement when moving from the transmission time to the reception time Delay time in at least one of the signal delay time calculating means is characterized by being configured to be corrected.

  According to this invention, at least the transmission delay time calculating means or the reception delay time calculating means so that the reception-side focal position matches the transmission-side focal position at the reception position after the probe has moved. On the other hand, since the delay time is corrected, the shift of the focal position between transmission and reception due to movement by scanning is corrected. As a result, the SN ratio (signal-to-noise ratio) of the received signal is improved and the defect detection sensitivity is improved.

The invention according to claim 2 further comprises movement amount calculation means for calculating the movement amount of the probe by integrating the movement speed of the scanning means and the time difference between transmission and reception of the probe, based on the movement amount. The reception delay time is corrected so that the reception-side focal position matches the transmission-side focal position during reception.
According to the second aspect of the invention, the delay time on the receiving side is corrected in accordance with the amount of movement of the probe from the time of transmission to the time of reception. That is, if the amount of movement is obtained, a new refraction angle and path distance can be calculated with respect to the focus position on the transmission side that has already been set, and the delay time on the reception side is determined on the condition of this new refraction angle and path distance. Recalculated.
Therefore, the amount of movement is calculated by integrating the moving speed of the scanning means and the transmission / reception time difference of the probe, and based on this amount of movement, the reception side delay time and frequency are recalculated to set the reception delay time. Thus, the deviation of the focal position between the transmission and the reception due to the movement of the probe is corrected.

According to a third aspect of the present invention, there is provided movement amount calculating means for calculating the movement amount of the probe based on a detection signal from a position detection sensor, and the receiving-side focal position is determined based on the movement amount during reception. The reception delay time is corrected so as to match the focal position on the transmission side.
According to the third aspect of the invention, since the amount of movement of the probe is obtained from the detection signal from the position detection sensor, it is effective when the speed control of the scanning means for scanning the probe is difficult and the speed cannot be calculated. As in the second aspect, the reception delay time can be appropriately calculated according to the amount of movement of the probe from the time of transmission to the time of reception. The deviation of the focal position is corrected.

According to a fourth aspect of the present invention, the moving speed of the probe is constant, and the transmission delay time calculating means or the transmission side focal position is matched so that the reception side focal position coincides with the transmission side focal position during reception. A delay time is preset in at least one of the reception delay time calculating means.
According to the fourth aspect of the present invention, by moving the probe at a constant speed during scanning by the scanning means, the amount of movement of the probe becomes constant during the flaw detection, and when the reception position is reached, the probe is just transmitted. The transmission delay time and the reception delay time can be set in advance so that the focal position on the side coincides with the focal position on the reception side. Accordingly, the deviation of the focal position between the transmission and reception due to the movement of the probe is corrected.
Further, since it is not necessary to calculate the amount of movement of the probe or to detect it with the position detection sensor, it is only necessary to set a delay time in advance, thereby simplifying the device configuration and control.

According to a fifth aspect of the present invention, the moving position of the probe is detected two-dimensionally or three-dimensionally, and the focal position on the receiving side at the time of reception is determined based on a shift amount calculated from the position information. The reception delay time is corrected so as to match the focal position on the transmission side.
According to the fifth aspect of the present invention, even when scanning a complicated shape surface, it is possible to prevent the deviation of the focal position at the time of transmission / reception accompanying the movement of scanning, and to perform inspection with high sensitivity and high detectability. .

  The inventions according to claims 6 to 9 relate to an ultrasonic flaw detection method, and the invention according to claim 6 relates to a phased array ultrasonic flaw detection in which a plurality of transducers are arranged in a line. In the ultrasonic flaw detection method using a child, a required delay time for each transducer is calculated in order to simultaneously focus the ultrasonic beam emitted by each transducer on the transmission-side focal position in the subject. A required delay time for each transducer at the time of reception is calculated so as to converge to the focal position on the receiving side, and the probe is moved along the surface of the subject by the scanning means. It is characterized in that at least one of the transmission delay time and the reception delay time is corrected so that the reception-side focal position coincides with the transmission-side focal position at the reception position of the touch element.

  According to the sixth aspect of the present invention, the transmission delay time or the reception delay time is set so that the reception-side focal position matches the transmission-side focal position at the reception position after the probe has moved. Since at least one of them is corrected, the deviation of the focal position between the transmission and reception of the probe moved by scanning is corrected. As a result, the SN ratio (signal-to-noise ratio) of the received signal is improved and the defect detection sensitivity is improved.

  The invention according to claim 7 is characterized in that the reception delay time is corrected based on the amount of movement of the probe so that the focal position on the reception side coincides with the focal position on the transmission side during reception. And

  According to the seventh aspect of the invention, the reception delay time is corrected in accordance with the amount of movement of the probe from the time of transmission to the time of reception. That is, if the amount of movement is obtained, a new refraction angle and path distance can be calculated for the focus position on the transmission side that has already been set, and the reception delay time and frequency are set on the condition of this new refraction angle and path distance. Is recalculated. Accordingly, by receiving with the reception delay time after this recalculation, the deviation of the focal position between the transmission and reception of the probe moved by scanning is corrected.

  According to an eighth aspect of the present invention, the transmission delay time is previously set so that the probe is moved at a constant moving speed and the reception-side focal position coincides with the transmission-side focal position during reception. And a delay time of the reception is set.

According to the invention described in claim 8, by moving the probe at a constant speed during scanning by the scanning means, the amount of movement of the probe becomes constant during the flaw detection, and when the reception position is reached, the probe is just transmitted. The transmission delay time and the reception delay time can be set in advance so that the focal position on the side coincides with the focal position on the reception side. Accordingly, the deviation of the focal position between the transmission and reception due to the movement of the probe is corrected.
Further, since it is not necessary to calculate the amount of movement of the probe or to detect it with the position detection sensor, it is only necessary to set a delay time in advance, thereby simplifying the device configuration and control.

According to the ninth aspect of the present invention, the moving position of the probe is detected two-dimensionally or three-dimensionally, and the focal position on the receiving side at the time of reception is determined based on a shift amount calculated from the position information. The reception delay time is corrected so as to match the focal position on the transmission side.
According to the ninth aspect of the present invention, even when a complicated shape surface is scanned, it is possible to perform a highly sensitive and highly detectable inspection by preventing a shift of the focal position at the time of transmission and reception accompanying the movement of scanning. .

  According to the present invention, when the probe is scanned and the transmission position and the reception position move, especially when the subject is thick and the defect exists at a deep position, the transmission and reception It is possible to provide an ultrasonic flaw detection apparatus and method using a phased array ultrasonic flaw detection probe that can perform a flaw detection with high detection sensitivity while preventing focus deviation.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Only.

  In the drawings to be referred to, FIG. 1 is a block diagram showing a first embodiment of an ultrasonic flaw detection apparatus and method according to the present invention, and FIG. 2 is an explanatory view of a phased array ultrasonic flaw detection probe (a ) Is an illustration of focusing in a straight direction, and (b) is an explanatory view of focusing in an oblique direction. FIG. 3 is a control flow diagram of the first embodiment, and FIG. 4 is an operation explanatory diagram of the first embodiment. FIG. 5 is a configuration block diagram of the second embodiment, and FIG. 6 is a control flow diagram of the second embodiment. FIG. 7 is an operation explanatory diagram of the third embodiment, FIG. 8 is a block diagram of the configuration of the third embodiment, and FIG. 9 is a control flow diagram of the third embodiment. FIG. 10 is an explanatory diagram of the fourth embodiment, (a) is an explanatory diagram of scanning by raster scanning, (b), (c) are the focal position and delay time of an ultrasonic beam in different scanning directions. It is explanatory drawing of a timing. FIG. 11 is an explanatory diagram showing the focal position relationship of the ultrasonic beam of the fifth embodiment, FIG. 12 is an explanatory diagram of the coordinate relationship of the fifth embodiment, and FIG. 13 is a configuration of the fifth embodiment. FIG. 14 is a block diagram, and FIG. 14 is a control flow diagram of the fifth embodiment.

(First embodiment)
The first embodiment will be described with reference to FIGS. As shown in FIG. 1, the probe 1 is a phased array ultrasonic flaw detector in which a plurality of transducers 3 are arranged in a line. In order to efficiently propagate ultrasonic waves into the subject 7, a contact medium 9 such as glycerin is applied to the flaw detection surface.

  In the phased array ultrasonic flaw detector, as shown in FIG. 2, a plurality of transducers 3 are arranged in a line, ultrasonic waves are emitted from the respective transducers 3, and the respective transducers 3 are made independent. To control. A combined wavefront of ultrasonic waves from each transducer 3 can be formed to focus the ultrasonic beam at an arbitrary point or to swing the ultrasonic beam at an arbitrary angle. For example, FIG. 2A shows a case where the ultrasonic beam is focused at a point P in the straight direction, and the ultrasonic wave transmission timing of each transducer 3, that is, the timing of the delay time is shown by a bar graph. FIG. 2B shows the case where the ultrasonic beam is focused on the point P in the oblique direction.

  In order to simultaneously focus the ultrasonic beam emitted by each transducer 3 on the target, it is necessary to obtain a predetermined delay time for each transducer 3. This delay time is calculated from the distance of the target to be focused and the path distance between each transducer 3, and the vibration frequency of each transducer 3 is calculated from the refraction angle to the target.

As shown in the configuration block diagram of FIG. 1, in the first embodiment, the ultrasonic beam emitted by each transducer 3 is simultaneously applied to the focal position P1 on the transmitting side in the subject 7 (see FIG. 15B). Transmission delay time calculating means 11 for calculating a required delay time for each transducer 3 for focusing;
A reception delay time calculating means 13 for calculating a required delay time for each transducer at the time of reception so as to converge to a focal position P2 on the reception side in the subject 7 (see FIG. 15B), and a probe; And scanning means 15 for moving 1 along the surface of the subject 7.

  Further, the amount of movement of the probe 1 by the scanning unit 15 is received from the moving speed V (t) of the scanning unit 15 and the transmission of the probe 1 instructed from the probe control unit 16 to the probe 1. Movement amount calculation means 17 that is calculated by integration with the time difference (Δt) until the reception-side focal position P2 is changed to the transmission-side focal position P1 based on the movement amount calculated by the movement amount calculation means 17 during reception. Correction means 19 is provided for recalculating and correcting the reception delay time so as to match.

Next, correction of the reception delay time will be described with reference to the control flowchart shown in FIG. First, in step S2, the transmission delay time calculating means 11 calculates a required delay time for simultaneously focusing the ultrasonic beam emitted by each transducer 3 on the transmission-side focal position P1 in the subject 7, and step S4. Then, ultrasonic waves are transmitted from each transducer 3 according to the delay time.
Next, in step S6, an ultrasonic wave reflected from the subject 7 is received. In step 8, the movement amount calculation means 17 calculates the movement amount by integrating the movement speed V (t) of the scanning means 15 and the time difference (Δt) from transmission to reception of the probe 1.

Next, in step S10, based on the movement amount calculated by the movement amount calculation means 17, the reception delay time is calculated so that the reception-side focal position P2 coincides with the transmission-side focal position P1 during reception. Specifically, when the movement amount f is obtained as shown in FIG. 4, a new refraction angle θ ′, path length between the probe 1 after movement and the transmission-side focal position P1 that has already been set. The distance W ′ can be calculated. On the condition of this new refraction angle θ ′ and path distance W ′, the delay time on the receiving side is recalculated. In FIG. 4, an arrow h indicates the moving direction of the probe 1, and a refraction angle θ and a path distance W indicate a refraction angle and a path distance on the transmission side.
In step S12, the received signal is calculated by synthesizing the ultrasonic signal received by the received signal processing means 20 with the recalculated reception side delay time.

  According to the first embodiment described above, the delay time is reset in the reception delay time calculation means 13 so that the reception-side focal position P2 coincides with the transmission-side focal position P1 at the reception position after the movement of the probe. Since the delay time is calculated and corrected, the shift of the focal position between transmission and reception due to movement of the probe is corrected. As a result, the SN ratio (signal-to-noise ratio) of the received signal is improved and the defect detection sensitivity is improved.

  Also, the amount of movement is calculated by integrating the moving speed of the scanning means and the transmission / reception time difference of the probe, and based on this amount of movement, the reception side delay time and frequency are recalculated to set the reception delay time. Thus, the deviation of the focal position between transmission and reception due to movement by scanning is corrected.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS. In the second embodiment, the movement amount is directly detected using an encoder 21 which is a position sensor, instead of the movement amount calculation means 17 of the first embodiment.

FIG. 5 is a block diagram corresponding to FIG. 1 is the same as that of the first embodiment except that the encoder 21 of the position sensor is changed, and the description thereof will be omitted.
FIG. 6 shows a control flow diagram corresponding to FIG. The only difference between the ultrasonic wave reception in step S16 and the movement amount reception in step S18 is the same as in the first embodiment. In step S16, an ultrasonic wave reflected from the subject 7 is received, and in step S18, a movement amount signal from the encoder 21 is input. These steps S16 and S18 are processed at the same time, and after that, in step S10, the reception-side focal position P2 coincides with the transmission-side focal position P1 during reception based on the movement amount calculated by the movement amount calculation means 17. Calculate the reception delay time.

  According to the second embodiment described above, since the movement amount of the probe is obtained from the detection signal from the encoder 21 of the position detection sensor, it is difficult to control the speed of the scanning means for scanning the probe, and the speed cannot be calculated. As is the case with the first embodiment, the reception delay time can be appropriately calculated according to the amount of movement of the probe from the time of transmission to the time of reception. Deviation of the focal position between transmission and reception is corrected, and flaw detection sensitivity is improved.

(Third embodiment)
Next, a third embodiment will be described with reference to FIGS. In the third embodiment, in the first and second embodiments, the correction of the focal position shift due to the movement of the probe is performed by recalculating the delay time on the reception side based on the movement amount. The correction is performed by setting the delay time of the transmission side or the reception side or both in advance.

That is, in the third embodiment, the probe 1 is moved at a constant speed by the scanning unit 15, and because of the constant speed, the reception-side focal position P2 coincides with the transmission-side focal position at the time of reception. As described above, the delay time is set in advance in the transmission delay time calculation means 11 and the reception delay time calculation means 13.
As shown in FIG. 7A, when the probe 1 is stopped, the focal position P1 on the transmission side and the focal position P2 on the reception side are set in advance to a position that is even shifted by the movement amount f between transmission and reception. Then, the delay time is set so as to converge at the shifted positions P1 and P2. The beam shape at the time of stop is indicated by a solid line on the transmission side and a dotted line on the reception side. Then, as shown in FIG. 7B, the probe 1 is scanned in the direction of the arrow h and moved by the movement amount f so that they are matched as shown in FIG.
The delay time for correcting the shift of the focal position may be set by setting the transmitting side and the receiving side, respectively, and may be only one receiving side or only the transmitting side.

  FIG. 8 shows a configuration block diagram corresponding to FIG. The movement amount calculation means 17 is not provided, but the point that the correction means 23 is provided in the transmission delay time calculation means 11 and the correction means 19 is provided in the reception delay time calculation means 13 is changed. The same reference numerals are used and description thereof is omitted.

FIG. 9 shows a control flow diagram corresponding to FIG. Only the transmission delay time calculation in step S21 and the reception delay time calculation in step S22 are changed.
In step S21, a transmission delay time for correcting the deviation of the focal position is calculated and set in advance. In step S22, a transmission delay time for correcting the deviation of the focal position is calculated and set in advance.
In step S12, the ultrasonic signal received by the reception signal processing means 20 is synthesized by the delay time on the reception side set in step S22, and the reception signal is calculated.

As described above, according to the third embodiment, when the probe is moved at a constant speed during scanning by the scanning unit 15, the amount of movement of the probe becomes constant during the flaw detection, and when the reception position is reached, the probe is transmitted. The transmission delay time and the reception delay time can be set so that the focal position on the side coincides with the focal position on the reception side. Therefore, the shift of the focal position between transmission and reception due to movement by scanning is corrected, and the flaw detection sensitivity is improved.
Further, since it is not necessary to calculate the amount of movement of the probe 1 at the time of reception or to detect the position with a position detection sensor such as the encoder 21, it is only necessary to set a delay time in advance. Simplify.

(Fourth embodiment)
Next, FIG. 10 shows a fourth embodiment. The fourth embodiment is a modification of the third embodiment, and the focal positions at the time of transmission and at the time of reception when the scanning means 15 moves the probe 1 by a raster scanning method for flaw detection over a wide range. This is an example of correcting the deviation.

This raster scanning method refers to flaw detection by reciprocating scanning within a certain range. As shown in FIG. 10A, the h1 direction and the h2 direction are moved repeatedly. At this time, the front and rear of the probe 1 are switched with respect to the traveling direction in the h1 direction and the h2 direction.
While maintaining the setting relationship between the transmission delay time and the reception delay time set in the third embodiment, that is, while maintaining the setting relationship of the delay time in which the shift of the focal position between transmission and reception is corrected, For example, the transmission delay time delay timing pattern T2 and the reception delay time delay timing pattern T1 and the reception delay time delay timing pattern T1 and the reception delay time delay timing pattern R1 in the reverse h2 direction, respectively. The pattern R2 can correspond to the scan in the h2 direction from the scan in the h1 direction by using the relational expressions of T2 = R1 and R2 = T1.

FIG. 10B shows the focal position P1 of the ultrasonic beam at the time of stopping when scanning in the h1 direction (the focusing position on the transmission side, the solid beam shape) and the focal position P2 (the focusing position on the reception side, the dotted line (Beam shape) relationship is shown.
FIG. 10C shows the focal position P1 (focusing position on the transmission side, beam shape of solid line) and focal position P2 (on the receiving side) of the ultrasonic beam when stopped when scanning in the h2 direction opposite to h1. The relationship between the focusing position and the dotted beam shape) is shown.

According to the fourth embodiment, even when the scanning unit 15 moves the probe 1 by a raster scanning method for flaw detection over a wide range, the deviation of the focal position between transmission and reception is corrected to detect flaws. Sensitivity is improved.
Further, since it is only necessary to replace the delay timing pattern with a reverse relationship with respect to the reciprocating scanning, a wide area can be detected with high sensitivity by simple control, so that flaw detection efficiency is improved.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to FIGS. The fifth embodiment is an example in which the deviation of the focal position with respect to the curved subject 7 is corrected. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 11 shows a focused state of the ultrasonic beam. If the delay time for correcting the shift of the focal position due to the movement of the probe 1 is not set as shown in FIG. 11A, in the case of a curved surface shape, the focal position P1 on the transmitting side and the receiving side are adjusted. The focal position P2 deviates greatly from a plane flaw detection surface. In FIG. 11 (a), the beam moves in the h direction, the solid line beam shape indicates the time of transmission, and the dotted line beam shape indicates the time of reception. FIG. 11B shows a case where the delay time on the reception side is corrected, and the focal position P1 on the transmission side coincides with the focal position P2 on the reception side.

  FIG. 13 shows a configuration block diagram corresponding to FIG. The change amount calculation means 28 acquires position shape information as a function of time, and this position shape information and a time difference from transmission to reception of the probe 1 instructed to the probe 1 from the probe control means 16 ( The position change amount is calculated by integration with Δt). Further, a correction unit that recalculates and corrects the reception delay time so that the reception-side focal position P2 coincides with the transmission-side focal position P1 based on the position variation calculated by the variation calculation unit 28. 29.

Here, as shown in FIG. 12, a case will be described in which the subject 7 is a curved surface whose Z coordinate changes in the X direction but has a constant Z coordinate in the Y direction. Each transducer 3 arranged in the X direction in the probe 1 is attached so as to be movable in the Z direction, and each transducer 3 moves in the Z direction following a curved flaw detection surface. The amount of movement is detected by the detection means 30 in the probe 1. The position information on the XY coordinates is detected by the encoder 21.
As described above, the position information of the probe 1 is obtained by the detection unit 30 and the encoder 21 and is given to the change amount calculation unit 28.

FIG. 14 shows a control flow diagram corresponding to FIG. First, in step S32, the transmission delay time calculation means 11 calculates a required delay time for converging the ultrasonic beam emitted by each transducer 3 to the transmission-side focal position P1 in the subject 7 at the same time. At this time, the focal position P1 is calculated on the basis of two-dimensional position information because of the shape change, in the example of this embodiment, based on position information on the XZ plane.
In step S4, ultrasonic waves are transmitted from each transducer 3 according to the delay time, and in step S6, ultrasonic waves reflected from the subject 7 are received. In step 34, the change amount calculation means 28 calculates the change amount by integrating the transmission / reception time difference (Δt) and the position information obtained by the detection means 30 and the encoder 21.

Next, in step S36, based on the amount of change calculated by the amount-of-change calculator 28, the reception delay time is calculated so that the reception-side focal position P2 coincides with the transmission-side focal position P1 during reception.
Specifically, as in the first embodiment, if the change amount of the probe 1 is obtained, a new value between the moved probe 1 and the transmission-side focal position P1 that has already been set is obtained. A refraction angle θ ′ and a path distance W ′ can be calculated. On the condition of this new refraction angle θ ′ and path distance W ′, the delay time on the receiving side for each transducer 3 is recalculated.
In step S38, the received signal is calculated by synthesizing the ultrasonic signals received by the received signal processing means 20 with the recalculated delay time on the receiving side.

  According to the fifth embodiment, the delay time is recalculated in the reception delay time calculation means 13 so that the reception-side focal position P2 coincides with the transmission-side focal position P1 at the reception position after the movement of the probe. Thus, since the delay time is corrected, the deviation of the focal position between transmission and reception due to the movement of the probe is corrected. As a result, the SN ratio (signal-to-noise ratio) of the received signal is improved and the defect detection sensitivity is improved.

Also, the amount of change is calculated by integrating the moving speed of the scanning means and the time difference between transmission and reception of the probe, and based on this amount of change, the delay time and frequency on the receiving side are recalculated to set the reception delay time. Thus, the deviation of the focal position between transmission and reception due to movement by scanning is corrected.
Therefore, even when scanning a complicated curved curved surface, it is possible to prevent the deviation of the focal position at the time of transmission and reception, and to perform inspection with high sensitivity and high detectability.

  In the above description of the fifth embodiment, as shown in FIG. 12, the subject 7 has a curved surface in which the Z coordinate changes in the X direction but the Z coordinate is constant in the Y direction. Explained the case. That is, the two-dimensional change has been described. Similarly, when the subject 7 is a three-dimensional object in which the Z coordinate changes with respect to the Y direction, the position change amount is similarly obtained to determine the focal position at the time of transmission and reception. Misalignment can be corrected. For example, in the case of using a matrix array probe, it is possible to obtain three-dimensional position information and correct a focus position shift between transmission and reception.

  According to the present invention, when the probe is scanned and the transmission position and the reception position move, especially when the subject is thick and the defect exists at a deep position, the transmission and reception Since flaws can be prevented and flaw detection with high detection sensitivity can be performed, it is useful when applied to an ultrasonic flaw detection apparatus using a phased array ultrasonic flaw detection probe.

1 is a configuration block diagram showing a first embodiment of an ultrasonic flaw detector according to the present invention. It is explanatory drawing of a phased array ultrasonic flaw detector, (a) is a straight direction focusing, (b) is an explanatory drawing of the diagonal focusing. It is a control flow figure of a 1st embodiment. It is operation | movement explanatory drawing of 1st Embodiment. It is a block diagram of the configuration of the second embodiment. It is a control flow figure of a 2nd embodiment. It is operation | movement explanatory drawing of 3rd Embodiment. It is a block diagram of the configuration of the third embodiment. It is a control flow figure of a 3rd embodiment. FIG. 10 is an explanatory diagram of a fourth embodiment, (a) is an explanatory diagram of scanning by a raster scan, and (b), (c) is an explanation of the focal position relationship and delay time timing of an ultrasonic beam in different scanning directions. FIG. It is explanatory drawing which shows the focusing position relationship of the ultrasonic beam of 5th Embodiment. It is explanatory drawing of the coordinate relationship of 5th Embodiment. It is a block diagram of the configuration of the fifth embodiment. It is a control flow figure of a 5th embodiment. It is explanatory drawing which shows the focusing state of the ultrasonic beam explaining a prior art, (a) shows the case where the beam diameter which is not focused is large, (b) shows the case where the beam diameter focused is small.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe 3 Vibrator 7 Subject 9 Contact medium 11 Transmission delay time calculation means 13 Reception delay time calculation means 15 Scanning means 17 Movement amount calculation means 19, 23, 29 Correction means 20 Received signal processing means 21 Encoder 28 Change amount Calculation means

Claims (9)

In an ultrasonic flaw detector using a phased array ultrasonic flaw detector in which a plurality of transducers are arranged in a row,
A transmission delay time calculating means for calculating a required delay time for each transducer in order to simultaneously focus the ultrasonic beam emitted by each transducer on the focal position on the transmission side in the subject;
A reception delay time calculating means for calculating a required delay time for each of the transducers at the time of reception so as to converge to the focal position on the reception side in the subject;
Scanning means for moving the probe along the surface of the subject,
The transmission delay time calculating means or the transmission side focal position so that the reception side focal position coincides with the transmission side focal position at the reception position after movement when the probe is moved from the transmission time to the reception time by the scanning means. An ultrasonic flaw detection apparatus, wherein the delay time is corrected in at least one of the reception delay time calculation means. A moving amount calculating means for calculating the moving amount of the probe by integrating the moving speed by the scanning means and the time difference between transmission and reception of the probe;
2. The ultrasonic flaw detection apparatus according to claim 1, wherein the reception delay time is corrected based on the amount of movement so that the focal position on the reception side coincides with the focal position on the transmission side during reception. A movement amount calculating means for calculating a movement amount of the probe by a detection signal from a position detection sensor;
2. The ultrasonic flaw detection apparatus according to claim 1, wherein the reception delay time is corrected based on the amount of movement so that the focal position on the reception side coincides with the focal position on the transmission side during reception.   At least one of the transmission delay time calculation means and the reception delay time calculation means so that the moving speed of the probe is constant and the reception-side focal position matches the transmission-side focal position at the time of reception. 2. The ultrasonic flaw detector according to claim 1, wherein a delay time is set in advance.   The moving position of the probe is detected two-dimensionally or three-dimensionally, and the focal position on the receiving side coincides with the focal position on the transmitting side at the time of reception based on the amount of displacement calculated from the positional information. The ultrasonic flaw detector according to claim 1, wherein the reception delay time is corrected as described above. In an ultrasonic flaw detection method using a phased array ultrasonic flaw detector in which a plurality of transducers are arranged in a row,
Calculate the required delay time for each transducer in order to simultaneously focus the ultrasound beam emitted by each transducer on the focal position on the transmitting side in the subject,
Calculate the required delay time for each transducer at the time of reception so as to converge to the focal position on the receiving side in the subject,
Moving the probe along the surface of the subject by scanning means;
At least one of the transmission delay time and the reception delay time is corrected so that the reception-side focal position matches the transmission-side focal position at the probe reception position after movement. Ultrasonic flaw detection method.   The ultrasonic wave according to claim 6, wherein a reception delay time is corrected so that a focus position on the reception side coincides with a focus position on the transmission side based on an amount of movement of the probe. Flaw detection method.   The probe is moved at a constant moving speed, and the transmission delay time and the reception delay time are set in advance so that the reception-side focal position coincides with the transmission-side focal position during reception. The ultrasonic flaw detector according to claim 6. The moving position of the probe is detected two-dimensionally or three-dimensionally, and the focal position on the receiving side coincides with the focal position on the transmitting side at the time of reception based on the amount of displacement calculated from the positional information. The ultrasonic flaw detector according to claim 6, wherein the reception delay time is corrected as described above.

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