Ultrasonic flaw detection device

Abstract

To provide an ultrasonic flaw detection device capable of performing support for determining defect properties.SOLUTION: An ultrasonic flaw detection device includes an ultrasonic sensor 11 arranged on the outer surface 2 of a piping 1 and including a plurality of piezo-electric elements 16a-16d, a control device 12 and a computer 13. The control device 12 acquires a plurality of waveform signals corresponding to the combination of a transmission element and a reception element out of the plurality of piezo-electric elements 16a-16d; and the computer 13 forming a flaw detection image using the plurality of waveform signals calculates the movement distance of the ultrasonic sensor 11 for creating a flaw detection image without overlapping the range of an inner surface echo with that of a defective echo in the axis direction of the piping 1 to display the calculated movement distance.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an ultrasonic flaw detector. [Background technology]

[0002] In power plant facilities, remaining life is evaluated based on the location and size of defects in the test specimen to ensure safety. One type of non-destructive testing device that detects defects in the test specimen is an ultrasonic flaw detector.

[0003] The ultrasonic flaw detector of Patent Document 1 includes a main body and a transducer connected to the main body via a cable. The transducer is disposed on the outer surface of a steel material (test object) and has a plurality of piezoelectric elements.

[0004] The main body of the ultrasonic flaw detection device sequentially selects one piezoelectric element and transmits ultrasonic waves from the piezoelectric element to the steel material, while acquiring signals that are the result of the reflected ultrasonic waves being received by the piezoelectric element and converted. In this way, a plurality of signals corresponding to the plurality of piezoelectric elements are acquired. Each signal includes an inner surface echo that corresponds to the ultrasonic waves reflected by the inner surface of the steel material. Furthermore, if a defect exists in the steel material, a defect echo that corresponds to the ultrasonic waves reflected by the defect in the steel material is also included.

[0005] The main body of the ultrasonic inspection device processes multiple signals based on the aperture synthesis method to construct an inspection image. The aperture synthesis method is a method for identifying the position of a reflection source from the viewpoint that the reflection source exists on an arc having a center at each piezoelectric element and a radius equal to the one-way propagation distance of the ultrasonic wave (more specifically, the value obtained by multiplying the propagation time and the propagation speed of the ultrasonic wave and dividing the result in half). The inspection image shows an echo on the image of the subject, i.e., shows the position of the reflection source. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-203037 A Summary of the Invention [Problem to be solved by the invention]

[0007] Although it is possible to obtain the position of a defect from the defect echo of a flaw detection image, it may be difficult to determine the nature of the defect. To explain in detail, in the flaw detection image, it may be possible to identify a defect echo located inside the subject, but a defect echo located on the inner surface of the subject may be buried in an inner surface echo and cannot be identified. In this case, it is difficult to determine whether the defect has occurred only inside the subject, or whether the defect (e.g., a crack) has occurred from the inner surface to the inside of the subject.

[0008] Patent Document 1 discloses a process for removing an internal echo from a flaw inspection image, for example, based on the difference between the intensity of a defect echo and the intensity of an internal echo. By performing this process, it is possible to confirm the presence or absence of a defect echo located on the internal surface of the object and determine the nature of the defect. However, depending on the shape of the object or the shape of the defect, the difference between the intensity of the internal echo and the intensity of the defect echo becomes small, making it difficult to remove the internal echo from the flaw inspection image.

[0009] A method of moving an ultrasonic sensor is known to create a flaw detection image in which the range of the inner echo and the range of the defect echo do not overlap in a predetermined direction parallel to the outer surface of the object. Using this method, it is possible to confirm the presence or absence of a defect echo located on the inner surface of the object and determine the nature of the defect. However, the moving distance of the ultrasonic sensor is generally determined by the inspector, and the movement of the ultrasonic wave may require trial and error depending on the skill of the inspector.

[0010] The present invention has been made in consideration of the above circumstances, and has an object to provide an ultrasonic flaw detector that can assist in determining defect properties. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides an ultrasonic inspection device that includes an ultrasonic sensor arranged on the outer surface of an object to be inspected and having a plurality of piezoelectric elements; a control device that selects a combination of a transmitting element and a receiving element from the plurality of piezoelectric elements, transmits ultrasonic waves from the transmitting element to the object to be inspected, and acquires a waveform signal obtained by receiving the reflected ultrasonic waves and converting them into a waveform signal, thereby acquiring a plurality of waveform signals corresponding to the combination of the transmitting element and the receiving element; and a computer that extracts and sums the intensities of the plurality of waveform signals based on the propagation time of the ultrasonic waves corresponding to the combination of the transmitting element and the receiving element when it is assumed that the ultrasonic waves are reflected at each position inside the object to construct an inspection image showing the distribution of the summed intensities. The computer calculates a moving distance of the ultrasonic sensor to create the inspection image in which the range of the inner echo and the range of the defect echo do not overlap in a predetermined direction parallel to the outer surface of the object, and displays the calculated moving distance, or moves the ultrasonic sensor based on the calculated moving distance. Effect of the Invention

[0012] According to the present invention, it is possible to provide assistance for determining defect properties. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram illustrating a configuration of an ultrasonic flaw detection device according to a first embodiment of the present invention. [Diagram 2] 3A to 3C are diagrams illustrating the arrangement of ultrasonic sensors and flaw detection images before the ultrasonic sensors are moved in the first embodiment of the present invention. [Diagram 3] 4A to 4C are diagrams illustrating the arrangement of ultrasonic sensors and flaw detection images after the ultrasonic sensors are moved in the first embodiment of the present invention. [Figure 4] 10A and 10B are diagrams illustrating the arrangement of ultrasonic sensors and flaw detection images before the ultrasonic sensors are moved in the second embodiment of the present invention. [Diagram 5] 13A and 13B are diagrams illustrating the arrangement of ultrasonic sensors and flaw detection images after the ultrasonic sensors are moved in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A first embodiment of the present invention will be described with reference to the drawings.

[0015] 1 is a schematic diagram showing the configuration of an ultrasonic flaw detector in the present embodiment. Note that the present embodiment will be described taking as an example a case where flaw detection testing of a pipe is performed.

[0016] The ultrasonic flaw detection device of this embodiment includes an ultrasonic sensor 11 arranged on an outer surface 2 of a pipe 1 (test object), a control device 12 connected to the ultrasonic sensor 11 via wiring, a computer 13 connected to the control device 12 via wiring, and a display device 14 and an input device 15 connected to the computer 13 via wiring. The computer 13 has, for example, a processor that executes processing according to a program, and a memory that stores the program and data. The display device 14 is composed of a display or the like, and the input device 15 is composed of a keyboard, a mouse, or the like.

[0017] The ultrasonic sensor 11 has a plurality of piezoelectric elements 16a, 16b, 16c, and 16d arranged in the axial direction (left-right direction in FIG. 1) of the pipe 1. Each piezoelectric element oscillates in response to a drive signal, which will be described later, and transmits ultrasonic waves to the pipe 1. In addition, each piezoelectric element receives reflected ultrasonic waves and converts them into a waveform signal.

[0018] The control device 12 has a pulser (not shown) that selects a transmitting element from among the piezoelectric elements 16a, 16b, 16c, and 16d and outputs a drive signal to the transmitting element, and a receiver (not shown) that selects a receiving element from among the piezoelectric elements 16a, 16b, 16c, and 16d and inputs a waveform signal from the receiving element. The control device 12 obtains a plurality of waveform signals corresponding to the combinations of the transmitting element and the receiving element by selecting and controlling a combination of the transmitting element and the receiving element from among the piezoelectric elements 16a, 16b, 16c, and 16d.

[0019] More specifically, the pulser first selects the piezoelectric element 16a as a transmitting element and causes the piezoelectric element 16a to transmit ultrasonic waves. The receiver selects the piezoelectric elements 16a, 16b, 16c, and 16d as receiving elements and receives the waveform signals W input from the piezoelectric elements 16a, 16b, 16c, and 16d. aa ,W ab ,W ac ,W ad Next, the pulser selects the piezoelectric element 16b as a transmitting element and causes the piezoelectric element 16b to transmit ultrasonic waves. The receiver selects the piezoelectric elements 16a, 16b, 16c, and 16d as receiving elements and obtains the waveform signal W input from the piezoelectric elements 16a, 16b, 16c, and 16d. ba ,W bb ,W bc ,W bd Next, the pulser selects the piezoelectric element 16c as a transmitting element and causes the piezoelectric element 16c to transmit ultrasonic waves. The receiver selects the piezoelectric elements 16a, 16b, 16c, and 16d as receiving elements and obtains the waveform signal W input from the piezoelectric elements 16a, 16b, 16c, and 16d. ca ,W cb ,W cc ,W cd Next, the pulser selects the piezoelectric element 16d as a transmitting element and causes the piezoelectric element 16d to transmit ultrasonic waves. The receiver selects the piezoelectric elements 16a, 16b, 16c, and 16d as receiving elements and obtains the waveform signal W input from the piezoelectric elements 16a, 16b, 16c, and 16d. da ,W db ,W dc ,W dd In this way, multiple waveform signals W are obtained by switching the combination of transmitting elements and receiving elements. aa ~W dd The receiver digitizes the multiple waveform signals and outputs them to the computer 13.

[0020] For each position inside the pipe 1, the computer 13 extracts and sums the intensities (amplitudes) of multiple waveform signals based on the propagation time of the ultrasound corresponding to the combination of transmitting and receiving elements when it is assumed that the ultrasound is reflected at that position, and constructs a flaw detection image showing the distribution of the summed intensities.

[0021] More specifically, the computer 13 stores in advance the positional relationship of the piezoelectric elements 16a, 16b, 16c, and 16d in the ultrasonic sensor 11. For the waveform signal Waa corresponding to the combination of the transmitting element 16a and the receiving element 16a, the computer 13 calculates the propagation distance of the ultrasonic wave from the transmitting element 16a to the receiving element 16a via the virtual reflection position based on the position of the transmitting element 16a, the position of the receiving element 16a, and the virtual reflection position, and calculates the propagation time by multiplying the propagation distance and the propagation speed of the ultrasonic wave. From the waveform signal Waa, the computer 13 extracts the intensity corresponding to the propagation time of the ultrasonic wave. Next, for the waveform signal Wab corresponding to the combination of the transmitting element 16a and the receiving element 16b, the computer 13 calculates the propagation distance of the ultrasonic wave from the transmitting element 16a to the receiving element 16b via the virtual reflection position based on the position of the transmitting element 16a, the position of the receiving element 16b, and the virtual reflection position, and calculates the propagation time by multiplying the propagation distance and the propagation speed of the ultrasonic wave. From the waveform signal Wab, the computer 13 extracts the intensity corresponding to the propagation time of the ultrasonic wave. Similarly, the intensities of waveform signals Wac to Wdd are extracted. Then, the intensities of the extracted waveform signals Waa to Wdd are summed up, and a pixel value corresponding to this is set. In this manner, a pixel value is set for each virtual reflection position, and a flaw detection image is constructed. Display device 14 displays the flaw detection image constructed by computer 13.

[0022] For example, when the ultrasonic sensor 11 is disposed on the outer surface 2 of the pipe 1 as shown in FIG. 2(a), the flaw detection image 21A shown in FIG. 2(b) is constructed by the computer 13 and displayed on the display device 14. The flaw detection image 21A shows an inner surface echo 22 corresponding to the ultrasonic wave reflected by the inner surface 3 of the pipe 1, a defect echo 23a corresponding to the ultrasonic wave reflected by the tip of the crack 4 of the pipe 1, and a defect echo 23b corresponding to the ultrasonic wave reflected by the root of the crack 4 of the pipe 1 in a two-dimensional coordinate system consisting of the axial direction (left-right direction in FIG. 2(b)) and the thickness direction (up-down direction in FIG. 2(b)) of the pipe 1. The range of the inner surface echo 22 in the axial direction of the pipe 1 is approximately the same as the sensor opening range (specifically, the range from the piezoelectric element 16a to the piezoelectric element 16d in the axial direction of the pipe 1). The ranges of the defect echoes 23a and 23b in the axial direction of the pipe 1 are approximately the same as each other.

[0023] The inspector obtains the position of the inner surface of the pipe 1 in the thickness direction (the center position of the inner surface echo 22) from the inner surface echo 22 of the flaw detection image 21A displayed on the display device 14. The inspector also obtains the position of the defect in the axial direction of the pipe 1 (the center position of the defect echo 23a) from the defect echo 23a of the flaw detection image 21A displayed on the display device 14. However, the defect echo 23b of the flaw detection image 21A is buried in the inner surface echo 22 and cannot be identified, so the nature of the defect cannot be determined. Therefore, the inspector inputs, using the input device 15, a command to calculate the moving distance of the ultrasonic sensor 11 to create a flaw detection image in which the range of the inner surface echo 22 in the axial direction of the pipe 1 (in other words, a predetermined direction parallel to the outer surface of the test object) and the ranges of the defect echoes 23a and 23b do not overlap each other.

[0024] The computer 13, in accordance with the above-mentioned command, calculates the moving distance of the ultrasonic sensor 11 for creating a flaw detection image in which the range of the inner surface echo 22 and the range of the defect echoes 23a and 23b do not overlap each other in the axial direction of the pipe 1, based on the information obtained from the flaw detection image 21A. In detail, the computer 13 extracts the inner surface echo 22 and the defect echo 23a from the flaw detection image 21A by image processing or input from the input device 15 by an inspector. Then, for example, the computer 13 calculates the distance A between the center O of the ultrasonic sensor 11 and the boundary of the range of the inner surface echo 22 in the axial direction of the pipe 1, and calculates the distance B between the center O of the ultrasonic sensor 11 and the boundary of the range of the defect echo 23a in the axial direction of the pipe 1. Then, based on the calculated distances A and B, the computer 13 calculates the moving distance D (=A-B+C) of the ultrasonic sensor 11 for creating a flaw detection image in which the range of the inner surface echo 22 and the range of the defect echo 23a are separated from each other by a predetermined value C in the axial direction of the pipe 1. The computer 13 causes the display device 14 to display the calculated moving distance D.

[0025] The inspector moves the ultrasonic sensor 11 based on the moving distance D displayed on the display device 14 (see FIG. 3(a)). After that, the control device 12 acquires a plurality of waveform signals again, and based on the signals, the computer 13 constructs the flaw detection image 21B (see FIG. 3(b)), and displays the flaw detection image 21B on the display device 14. In the flaw detection image 21B, the range of the inner surface echo 22 and the range of the defect echoes 23a and 23b are separated from each other in the axial direction of the pipe 1, and the defect echo 23b can be identified. The defect echoes 23a and 23b enable the inspector to determine that a crack 4 has occurred from the inner surface 3 to the inside of the pipe 1. If the defect echo 23b does not exist, the defect echo 23a enables the inspector to determine that a defect has occurred only inside the pipe 1.

[0026] As described above, the ultrasonic flaw detection device of this embodiment can provide assistance for determining defect properties.

[0027] A second embodiment of the present invention will be described with reference to the drawings. This embodiment differs from the first embodiment in the method of calculating the moving distance of the ultrasonic sensor. In this embodiment, the same parts as those in the first embodiment are given the same reference numerals, and the description will be omitted as appropriate.

[0028] For example, when the ultrasonic sensor 11 is disposed on the outer surface 2 of the pipe 1 as shown in FIG. 4(a), the flaw detection image 21A shown in FIG. 4(b) is constructed by the computer 13 and displayed on the display device 14. The inspector obtains the position of the inner surface in the thickness direction of the pipe 1 (the center position of the inner surface echo 22) from the inner surface echo 22 of the flaw detection image 21A displayed on the display device 14. The inspector also obtains the position of the defect in the axial direction of the pipe 1 (the center position of the defect echo 23a) from the defect echo 23a of the flaw detection image 21A displayed on the display device 14. However, the defect echo 23b of the flaw detection image 21A is buried in the inner surface echo 22 and cannot be identified, so the nature of the defect cannot be determined. Therefore, the inspector inputs a command using the input device 15 to calculate the moving distance of the ultrasonic sensor 11 to create a flaw detection image in which the range of the inner surface echo 22 and the ranges of the defect echoes 23a and 23b do not overlap each other in the axial direction of the pipe 1.

[0029] The computer 13, in accordance with the above-mentioned command, calculates the moving distance of the ultrasonic sensor 11 for creating a flaw detection image in which the range of the inner surface echo 22 in the axial direction of the pipe 1 and the range of the defect echoes 23a and 23b do not overlap with each other, based on the information obtained from the flaw detection image 21A. In detail, the computer 13 calculates a specific position P1 on the inner surface 3 of the pipe 1, which is the same as the position of the defect in the axial direction of the pipe 1, from the inner surface echo 22 and the defect echo 23a of the flaw detection image 21A. Then, the computer 13 calculates a specific position P2 on the outer surface 2 of the pipe 1, which is connected to the specific position P1 on the inner surface 3 of the pipe 1 by a straight line L inclined by a predetermined angle θ (for example, 45 degrees) in the axial direction of the pipe 1 with respect to the outer surface 2 of the pipe 1. Then, the computer 13 calculates a distance E by which the ultrasonic sensor 11 is moved so that the specific position P2 on the outer surface 2 of the pipe 1 and the center position O of the ultrasonic sensor 11 overlap with each other. The computer 13 causes the display device 14 to display the calculated moving distance E.

[0030] The inspector moves the ultrasonic sensor 11 based on the moving distance E displayed on the display device 14 (see FIG. 5(a)). After that, the control device 12 acquires a plurality of waveform signals again, and the computer 13 constructs the flaw detection image 21C (see FIG. 5(b)) based on the signals, and displays the flaw detection image 21C on the display device 14. In the flaw detection image 21C, the range of the inner surface echo 22 and the range of the defect echoes 23a and 23b are separated from each other in the axial direction of the pipe 1, and the defect echo 23b can be identified. In addition, by setting the predetermined angle θ to, for example, 45 degrees, the intensity of the defect echo 23b is increased, and the defect echo 23b can be identified. The inspector can determine that a crack 4 has occurred from the inner surface 3 to the inside of the pipe 1 based on the defect echoes 23a and 23b. If the defect echo 23b does not exist, it can be determined that a defect has occurred only inside the pipe 1 based on the defect echo 23a.

[0031] As described above, the ultrasonic flaw detection device of this embodiment can provide assistance for determining defect properties.

[0032] Although not specifically described in the second embodiment, depending on conditions such as the opening range of the ultrasonic sensor 11 and the thickness of the pipe 1, it may be impossible to create a flaw detection image in which the range of the inner surface echo 22 in the axial direction of the pipe 1 and the range of the defect echoes 23a, 23b do not overlap each other, even if the ultrasonic sensor 11 is moved by the moving distance E. Therefore, the computer 13 may calculate the moving distance D in the same manner as in the first embodiment, and select the larger of the moving distance D and the moving distance E to display on the display device 14.

[0033] In the first and second embodiments, the computer 13 displays the calculated movement distance on the display device 14, but the present invention is not limited to this. The computer 13 may control a moving device (not shown) based on the calculated movement distance to move the ultrasonic sensor 11. [Explanation of symbols]

[0034] 11 Ultrasonic Sensor 12 Control device 13. Computers 16a to 16d Piezoelectric elements

Claims

1. an ultrasonic sensor disposed on an outer surface of the subject and having a plurality of piezoelectric elements; a control device that selects a combination of a transmitting element and a receiving element from the plurality of piezoelectric elements, transmits ultrasonic waves from the transmitting element to the subject, and obtains waveform signals obtained by receiving and converting reflected ultrasonic waves by the receiving element, thereby obtaining a plurality of waveform signals corresponding to the combination of the transmitting element and the receiving element; and a computer that extracts and sums the intensities of the plurality of waveform signals based on a propagation time of the ultrasonic wave corresponding to a combination of the transmitting element and the receiving element when it is assumed that the ultrasonic wave is reflected at each position inside the subject, and constructs a flaw detection image showing a distribution of the summed intensities, The ultrasonic flaw detection device is characterized in that the computer calculates the movement distance of the ultrasonic sensor to create the flaw detection image in which the range of the internal echo and the range of the defect echo in a predetermined direction parallel to the outer surface of the specimen do not overlap with each other, and displays the calculated movement distance or moves the ultrasonic sensor based on the calculated movement distance.

2. The ultrasonic flaw detector according to claim 1, The ultrasonic flaw detection device is characterized in that the computer calculates the movement distance of the ultrasonic sensor to create the flaw detection image in which the range of the inner surface echo and the range of the defect echo are separated from each other by a predetermined value in the specified direction.

3. The ultrasonic flaw detector according to claim 1, The ultrasonic flaw detection device is characterized in that the computer calculates a specific position on the inner surface of the specimen that is the same as the position of the defect in the specified direction, calculates a specific position on the outer surface of the specimen that is connected to the specific position on the inner surface of the specimen by a straight line that is inclined at a specified angle in the specified direction relative to the outer surface of the specimen, and calculates a distance to move the ultrasonic sensor so that the specific position on the outer surface of the specimen overlaps with the center position of the ultrasonic sensor.

Images