JP6197458B2 - Defect inspection apparatus, defect inspection method, program, and storage medium - Google Patents

Description

  The present invention relates to a defect inspection apparatus and a defect inspection method for inspecting a defect contained in a welded steel pipe in which a weld is formed in the pipe axis direction, a program for causing a computer to execute the defect inspection method, and a computer for storing the program The present invention relates to a readable storage medium. In the present specification, an example in which the present invention is applied to an ERW steel pipe as a welded steel pipe will be described. However, the present invention is not limited to this, and other welded steel pipes such as arc welded steel pipes are used. It may be.

First, the general manufacturing method of an electric resistance steel pipe is demonstrated.
FIG. 16 is a schematic view showing an example of a general method for manufacturing an electric resistance welded steel pipe.
As shown in FIG. 16 (a), in a general method for manufacturing an electric resistance welded steel pipe, a plurality of roll groups (FIG. The butt end face 203 is melted by induction heating by a high frequency coil 204 or direct current heating by a contact tip (not shown), and upset is applied by a squeeze roll 205 to form a butt end face. 203 is welded to form a welded portion 210. In this way, as shown in FIG. 16B, the electric resistance welded steel pipe 200 in which the welded portion 210 is formed in the pipe axis direction 220 is manufactured.

  In the electric resistance welded pipe 200, the quality of the welded portion 210 is very important, and in the manufacturing process of the electric resistance welded pipe 200, on-line flaw detection is generally performed to determine whether or not there is a defect in the welded portion 210 by ultrasonic oblique angle flaw detection. It has been broken.

17 and 18 are schematic views showing an example of a general ultrasonic oblique angle flaw detection method.
17 and 18 show a cross section of the electric resistance welded steel pipe 200 shown in FIG. 16B (more specifically, the vicinity of the welded portion 210 in the cross section of the electric resistance welded steel pipe 200).

  In the ultrasonic oblique angle flaw detection method shown in FIG. 17, an ultrasonic flaw detector 251 that transmits and receives an ultrasonic beam is outside the outer surface 200G of the electric resistance welded pipe 200 and from the outer surface 200G of the electric resistance welded pipe 200 to a predetermined value. It is installed at a position separated by a distance. In the ultrasonic oblique angle flaw detection method shown in FIG. 17, an ultrasonic beam is output from the ultrasonic flaw detector 251 to the non-formation region of the welded portion 210 on the outer surface 200G of the electric resistance welded steel pipe 200. The acoustic beam is reflected once by the inner surface 200N of the ERW steel pipe 200 and transmitted to the welded portion 210. The reflected ultrasonic beam is received by the ultrasonic flaw detector 251, and the received ultrasonic beam is analyzed and the welded portion 210 is analyzed. Inspect whether or not there is a defect.

  The ultrasonic oblique angle flaw detection method shown in FIG. 18 is a method described in Patent Document 1 below, for example. Specifically, in the ultrasonic oblique angle flaw detection method shown in FIG. 18, an ultrasonic flaw detector 252 that transmits and receives an ultrasonic beam is installed in a region where the welded portion 210 is not formed on the outer surface 200 </ b> G of the electric resistance welded steel pipe 200. Yes. In the ultrasonic oblique angle flaw detection method shown in FIG. 18, an ultrasonic beam is transmitted directly from the ultrasonic flaw detector 252 to the welded portion 210, and the reflected ultrasonic beam is received by the ultrasonic flaw detector 252. The received ultrasonic beam is analyzed to check whether a defect exists in the welded portion 210.

Patent Document 2 below discloses a so-called tandem flaw detection technique in which separate ultrasonic flaw detectors are provided for transmission and reception of ultrasonic beams.
Patent Document 3 below discloses an ultrasonic flaw detection technique in which an ultrasonic flaw detector is provided on the outer upper surface of a welded portion of a welded steel pipe.

JP 2006-47026 A Japanese Patent No. 4544240 JP-A-10-158881

  In order to detect minute defects, it is advantageous to use high-frequency ultrasonic waves as much as possible. In this case, if the propagation distance of ultrasonic waves in the subject is long, attenuation of the ultrasonic waves becomes large. When the attenuation of the ultrasonic wave increases, the received signal of the ultrasonic wave decreases, so that it is difficult to distinguish from the noise component, and it becomes difficult to detect the defect.

  In this regard, the ultrasonic flaw detection method shown in FIGS. 17 and 18 described above has a limit in shortening the propagation distance of ultrasonic waves in the electric resistance welded steel pipe, and is insufficient as a technique for detecting minute defects. Met.

  Further, as described above, Patent Document 3 discloses a technique of an ultrasonic flaw detection method in which an ultrasonic flaw detector is provided on the outer upper surface of a welded portion of a welded steel pipe. Detection and evaluation of its dimensions (size) were limited.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a mechanism that enables detection of minute defects.

  As a result of intensive studies, the present inventor has conceived various aspects of the invention described below.

A defect inspection apparatus according to the present invention is a defect inspection apparatus for inspecting a defect contained in a welded steel pipe in which a weld portion is formed in a pipe axis direction, and is installed outside the outer surface of the welded steel pipe, and includes a plurality of ultrasonic waves A phased array probe in which transducers are arranged, and incident from the outside of the welded portion on the outer surface of the welded steel pipe, and focuses at least the welded portion near the inner surface of the welded steel pipe along the inner surface. Transmitting means for transmitting an ultrasonic beam that scans in the circumferential direction while changing the point from the phased array probe, and the reflected ultrasonic beam as a reflected ultrasonic beam via the phased array probe The receiving means for receiving, the position of the scanned inner surface in the first direction, and the direction from the outer surface to the inner surface of the welded steel pipe in the second direction, A defect inspection image generating means for generating a defect inspection image based on amplitude values of the wave beam, the defect determining means for determining whether a defect on the basis exists a defect inspection image generated by the defect inspection image generating means has the door, time waveforms of the ultrasonic beams transmitted from the transmitting means has a positive or negative of the first local peak, then, the first local peak and of opposite polarity second A third local peak having the same polarity as that of the first local peak, and the absolute value of the second local peak among the absolute values of the three local peaks is one. Ban magnitude rather, the defect determination unit, among the areas of the generated defect inspection image by the defect inspection image generating means, the time waveform of the ultrasonic beam received by the receiving unit is, positive or negative of the first local Has a peak, then Determining that there is no defect in a region having a second local peak having a polarity opposite to that of the first local peak and then having a third local peak having the same polarity as the first local peak; Of the region of the defect inspection image generated by the defect inspection image generating means, the time waveform of the ultrasonic beam received by the receiving means has a first local peak that is positive or negative, and then the first A second local peak having a polarity opposite to that of the first local peak, followed by a third local peak having the same polarity as the first local peak, and further thereafter, the first local peak It is determined that a defect exists in a region having a fourth local peak having a polarity opposite to that of the peak .

The defect inspection method of the present invention includes a phased array probe that is installed outside the outer surface of a welded steel pipe in which a weld is formed in the pipe axis direction, and in which a plurality of ultrasonic transducers are arranged, and the welded steel pipe A defect inspection method using a defect inspection apparatus for inspecting a defect contained in the welded steel pipe, which is incident from outside the welded portion on the outer surface of the welded steel pipe, and at least the welded portion near the inner surface of the welded steel pipe A transmitting step of transmitting from the phased array probe an ultrasonic beam that scans in a circumferential direction while changing a focal point along the surface; and the phased array probe using the reflected ultrasonic beam as a reflected ultrasonic beam. A receiving step for receiving via a contact, and a position of the scanned inner surface in a first direction, and a direction from the outer surface of the welded steel pipe toward the inner surface For the second direction, and the defect inspection image generating step of generating a defect inspection image based on the amplitude value of the reflected ultrasonic beam, or defect is present on the basis of the defect inspection image generated by the defect inspection image generating step A defect determination step for determining whether or not, and the time waveform of the ultrasonic beam transmitted in the transmission step has a positive or negative first local peak, and thereafter, the first local peak and Having a second local peak of opposite polarity, followed by a third local peak of the same polarity as the first local peak, and the second of the absolute values of the three local peaks the absolute value of the local peak top rather large, the defect judgment step, said one area of the defect inspection image generated defect inspection image generated by the step, the time of the ultrasonic beam received by the receiving step The shape has a first local peak that is positive or negative, followed by a second local peak of the opposite polarity to the first local peak, and then after that, the first local peak It is determined that there is no defect in a region having the third local peak of the same polarity, and the time waveform of the ultrasonic beam received in the reception step in the region of the defect inspection image generated by the defect inspection image generation step Has a first local peak that is positive or negative, followed by a second local peak of the opposite polarity to the first local peak, and then the same as the first local peak It is determined that there is a defect in a region having a third local peak with a polarity and then having a fourth local peak with a polarity opposite to the first local peak .

  The program of this invention is for making a computer perform each step in the said defect inspection method.

  The computer-readable storage medium of the present invention stores the program.

  According to the present invention, it is possible to detect minute defects.

It is a figure which shows an example of schematic structure of the defect inspection apparatus which concerns on embodiment of this invention. It is a schematic diagram which shows the embodiment of this invention and shows the mode of the defect inspection using the phased array probe shown in FIG. It is a figure which shows embodiment of this invention and shows an example of the received waveform of a certain reflected ultrasound beam received with the receiving part shown in FIG. It is a figure which shows embodiment of this invention and shows an example of the transmission waveform of the ultrasonic beam (transmission wave) transmitted from the transmission part shown in FIG. It is a figure for demonstrating embodiment of this invention and demonstrating the principle used as the receiving waveform of the reflected ultrasonic beam shown to FIGS. 3-1. FIG. 2 is a schematic diagram for explaining a defect inspection image generation process by a defect inspection image generation unit illustrated in FIG. 1 according to the embodiment of the present invention. FIG. 2 is a schematic diagram for illustrating a defect size calculation process by a defect size calculation unit illustrated in FIG. 1 according to the embodiment of the present invention. It is a flowchart which shows an example of the process sequence of the defect inspection method by the defect inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the Example of embodiment which concerns on this invention, and shows the sample of the ERW steel pipe used for the defect inspection. It is a figure explaining the flaw detection test using the water immersion point focused flaw detector performed about the 1st sample steel pipe shown to Fig.7 (a). The example of embodiment which concerns on this invention is shown, and the positional relationship of the phased array probe shown to FIG.1 and FIG.2 and the 1st sample steel pipe shown to FIG. 7 (a) and FIG. 8 (a) is shown. FIG. It is a figure which shows the Example of embodiment which concerns on this invention, and shows the defect inspection image obtained by the experiment shown in FIG. FIG. 10 shows an example of the embodiment according to the present invention, and an experiment using the defect inspection method according to the present invention in the positional relationship between the −4.5 ° phased array probe shown in FIG. 10 and the first sample steel pipe. FIG. The figure which shows the Example of embodiment which concerns on this invention, and shows the defect inspection image obtained by moving the position of a phased array probe in a Y direction ± 1.0 mm in FIG. 9, and the defect inspection method which concerns on this invention It is. The figure which shows the Example of embodiment which concerns on this invention, and shows the defect inspection image obtained by the defect inspection method which moves the position of a phased array probe in a Z direction in FIG. It is. The example of embodiment which concerns on this invention is shown, It is a figure which shows the experimental result using the defect inspection method which concerns on this invention using the 2nd sample steel pipe shown in FIG.7 (b). It is a flowchart which shows the Example of embodiment which concerns on this invention, and shows an example of the process sequence of the defect size calculation method in the experiment shown in FIG. It is a schematic diagram which shows an example of the manufacturing method of a general ERW steel pipe. It is a schematic diagram which shows an example of a general ultrasonic oblique angle flaw detection method. It is a schematic diagram which shows an example of a general ultrasonic oblique angle flaw detection method.

  Hereinafter, embodiments (embodiments) for carrying out the present invention will be described with reference to the drawings.

FIG. 1 is a diagram illustrating an example of a schematic configuration of a defect inspection apparatus 100 according to an embodiment of the present invention. This defect inspection apparatus 100 is an apparatus for inspecting defects included in an electric resistance welded steel pipe 200 which is a kind of welded steel pipe.
FIG. 2 is a schematic diagram showing a state of defect inspection using the phased array probe 110 shown in FIG. 1 according to the embodiment of the present invention. In FIG. 2, the same components as those shown in FIG. 1 and FIG. 16B are denoted by the same reference numerals.

  In this embodiment, the defect inspection apparatus 100 demonstrates the example supposing the case where the defect contained in the welding part 210 formed in the pipe-axis direction (220 of FIG. 2) of the ERW steel pipe 200 is inspected. 1 shows a cross section of the electric resistance welded pipe 200 shown in FIG. 2 (more specifically, the vicinity of the welded portion 210 in the cross section of the electric resistance welded pipe 200).

As shown in FIGS. 1 and 2, the defect inspection apparatus 100 according to the present embodiment is configured to include a phased array probe 110 and a control processing device 120.
As shown in FIG. 1, the control processing device 120 includes a subject condition input unit 121, a transmission / reception condition setting unit 122, a transmission / reception control unit 123, a transmission unit 124-1, a reception unit 124-2, The reception signal processing unit 125, the defect inspection image generation unit 126, the defect determination unit 127, the defect size calculation unit 128, and the recording / display unit 129 are configured. In the example illustrated in FIG. 1, the transmission unit 124-1 and the reception unit 124-2 are illustrated as independent configurations. However, for example, they may be configured as one transmission / reception unit 124.

As shown in FIGS. 1 and 2, the phased array probe 110 is installed outside the outer surface 200G of the ERW steel pipe 200 (more specifically, outside the outer surface 200G of the ERW steel pipe 200). A plurality of ultrasonic transducers 111 are arranged and formed at a position above the welded portion 210 that is a predetermined distance away from the outer surface 200G of the ERW steel pipe 200. Here, in this embodiment, it is assumed that the phased array probe 110 is provided with, for example, M ultrasonic transducers 111.
Further, between the phased array probe 110 and the outer surface 200G of the electric resistance welded steel pipe 200, as shown in FIG. 2, an ultrasonic beam 112 (ultrasonic beams 112-1 to 112-N shown in FIG. 1). Water is present as a medium for efficiently propagating water.
Further, the ultrasonic transducer 111 of the phased array probe 110 has a curved surface for focusing the ultrasonic beam 112 in the tube axis direction 220 as shown in FIG.

  The subject condition input unit 121 illustrated in FIG. 1 performs a process of inputting conditions (subject conditions) of the electric resistance welded steel pipe 200 that is the subject. For example, the subject condition input unit 121 performs a process of inputting the subject condition input by the user into the control processing device 120. Here, examples of the subject condition include an outer diameter (diameter), a pipe thickness, and a pipe making speed of the electric resistance welded pipe 200.

  The transmission / reception condition setting unit 122 illustrated in FIG. 1 performs processing for setting transmission / reception conditions based on the subject condition input by the subject condition input unit 121. For example, the transmission / reception condition setting unit 122 includes, as transmission / reception conditions, a water distance (distance between the phased array probe 110 and the outer surface 200G of the ERW steel pipe 200) and the number of channels used for transmission / reception (ultrasound used for transmission / reception). The number of transducers 111), the energy value of the transmission wave, the focusing depth / angle range / angle switching pitch of the transmission wave focused on the inner surface 200N, the amplification degree of the reception signal, and the time for recording the reception signal in one reception The width, the time interval for performing the nth and (n + 1) th transmission / reception, and the like are set.

  The transmission / reception control unit 123 illustrated in FIG. 1 controls the transmission unit 124-1, the reception unit 124-2, and the phased array probe 110 based on the transmission / reception conditions set by the transmission / reception condition setting unit 122.

  Table 1 below shows an example of the transmission / reception conditions set by the transmission / reception condition setting unit 122 and an example of the contents of control by the transmission / reception control unit 123 according to the transmission / reception conditions.

  Here, in the present embodiment, the transmission / reception control unit 123 performs M ultrasonic waves provided in the phased array probe 110 with respect to the transmission / reception condition of “number of channels used in transmission / reception” shown in Table 1. It is assumed that the vibrator 111 is set.

  The transmission unit 124-1 shown in FIG. 1 is based on the control by the transmission / reception control unit 123, and each ultrasonic beam 112-from the phased array probe 110 (more specifically, the M ultrasonic transducers 111). The process which transmits 1-112-N is performed. Specifically, the transmitter 124-1 is incident from the outside of the welded portion 210 on the outer surface 200G of the ERW steel pipe 200, and includes at least the welded portion 210 near the inner surface (near the inner surface 200N) of the ERW steel pipe 200. Ultrasound beams 112-1 to 112 -N that are scanned while changing the focal point along the surface 200 N are transmitted from the phased array probe 110.

  The receiving unit 124-2 shown in FIG. 1 uses the reflected ultrasonic beams 112-1 to 112-N as reflected ultrasonic beams based on the control by the transmission / reception control unit 123, and the phased array probe 110 (from Specifically, a process of receiving via M ultrasonic transducers 111) is performed.

  The reception signal processing unit 125 illustrated in FIG. 1 processes each reflected ultrasonic beam (reception signal) received by the reception unit 124-2. For example, the reception signal processing unit 125 performs a process of adding M reception signals received via the M ultrasonic transducers 111 for each reflected ultrasonic beam to form one combined reception signal. .

  The defect inspection image generator 126 shown in FIG. 1 takes the position of the inner surface 200N of the ERW steel pipe 200 scanned with the ultrasonic beams 112-1 to 112-N in the first direction (for example, the horizontal direction), and uses the ERW steel pipe 200. A process of generating a defect inspection image based on the amplitude value of each reflected ultrasonic beam received by the receiving unit 124-2 is performed with the direction from the outer surface 200G toward the inner surface 200N being a second direction (for example, the vertical direction). Here, the defect inspection image generation processing by the defect inspection image generation unit 126 will be described below with reference to FIGS.

3A illustrates an embodiment of the present invention, and the signal is received by the reception unit 124-2 illustrated in FIG. 1 (more specifically, after the signal processing is performed by the reception signal processing unit 125 illustrated in FIG. 1). FIG. 4 is a diagram illustrating an example of a received waveform of a certain reflected ultrasonic beam.
Here, the horizontal axis of FIG. 3A represents the time received by the receiving unit 124-2. The vertical axis in FIG. 3A represents the amplitude value of the reflected ultrasonic beam, and FIG. 3A illustrates the amplitude level of the reflected ultrasonic beam within a range of ± 100%.

  FIG. 3A shows a specific example in determining the black and white gradation when generating the defect inspection image. In the example illustrated in FIG. 3A, the color of the position where the amplitude value of the reflected ultrasonic beam is larger than 20 (%) which is the positive first threshold value 301 is white, and the amplitude value of the reflected ultrasonic beam is the above-described value. An example is shown in which the color at a position smaller than −20 (%), which is a negative second threshold 302 smaller than the first threshold 301, is black. Further, in the example illustrated in FIG. 3A, the amplitude value of the reflected ultrasonic beam is a value between the first threshold value 301 (20) and the second threshold value 302 (−20). An example in which the color is gray is shown. FIG. 3A is only an example in determining the black and white gradations when generating the defect inspection image, and the black and white gradations may be determined by other methods. Further, in the present embodiment, in FIG. 3A, the color at the position where the amplitude value of the reflected ultrasonic beam is larger than 20 (%) which is the first threshold value 301 is defined as white. A mode in which the white density is increased as the amplitude value of the reflected ultrasonic beam is larger in the range and the white has a gradation is also included in the present embodiment. Similarly, in the present embodiment, in FIG. 3-1, the color of the position where the amplitude value of the reflected ultrasonic beam is smaller than −20 (%), which is the second threshold 302, is defined as black. In this black range, an embodiment in which the density of black is increased as the amplitude value of the reflected ultrasonic beam is smaller, and the gradation is given to black is also included in this embodiment.

  Further, in FIG. 3A, a portion where the first white color, the first black color, and the second white color appear indicates a reception signal of the reflected ultrasonic beam reflected by the inner surface 200N of the ERW steel pipe 200, and the second The portion where the black color appears shows the reception signal of the reflected ultrasonic beam reflected by the defect existing in the vicinity of the inner surface 200N of the ERW steel pipe 200. This will be described in detail below with reference to FIGS. 3-2 and 3-3.

FIG. 3-2 is a diagram illustrating an example of a transmission waveform of an ultrasonic beam (transmission wave) transmitted from the transmission unit 124-1 illustrated in FIG. 1 according to the embodiment of the present invention. In FIG. 3-2, the horizontal axis indicates time, and the vertical axis indicates the amplitude value of the transmission wave. As shown in FIG. 3-2, the transmission waveform of the ultrasonic beam has a first local peak 321 having a positive polarity, followed by a second local peak 322 having a negative polarity, and then And a third local peak 323 having a positive polarity. That is, the first local peak 321 is provided immediately before and the third local peak 323 is provided immediately after the second local peak 322. Here, due to the characteristics of the phased array probe 110, the absolute value of the second local peak 322 is the largest value among the absolute values of the three local peaks. Further, as shown in the example of FIG. 3-2, the transmission waveform of the ultrasonic beam may show a drop of a small amplitude value having a negative polarity before the first local peak 321. The presence or absence of a small amplitude value does not affect the defect inspection of the present invention described below.
FIG. 3C is a diagram for explaining the principle of the reception waveform of the reflected ultrasonic beam shown in FIG. 3A according to the embodiment of the present invention.

FIG. 3A is a diagram illustrating a cross section of the electric resistance welded steel pipe 200. FIG. 3A illustrates a case where a defect exists near the inner surface 200N of the ERW steel pipe 200. FIG.
FIG. 3B is an example of the received waveform of the reflected ultrasonic beam reflected by the defect tip of the defect shown in FIG. 3A from the ultrasonic beam (transmission wave) shown in FIG. 3B. Is shown. In FIG. 3B, the horizontal axis indicates time, and the vertical axis indicates the amplitude value of the reflected ultrasonic beam. The reception waveform of the reflected ultrasonic beam shown in FIG. 3-3 (b) is based on the transmission waveform of the ultrasonic beam (transmission wave) shown in FIG. 3-2.
FIG. 3-3 (c) shows the reception of the reflected ultrasonic beam reflected by the inner surface 200N of the electric resistance welded steel pipe 200 shown in FIG. 3-3 (a) from the ultrasonic beam (transmission wave) shown in FIG. 3-2. An example of a waveform is shown. In FIG. 3C, the horizontal axis indicates time, and the vertical axis indicates the amplitude value of the reflected ultrasonic beam. The reception waveform of the reflected ultrasonic beam shown in FIG. 3-3 (c) is based on the transmission waveform of the ultrasonic beam (transmission wave) shown in FIG. 3-2.

Since the propagation distance of the transmission wave is shorter to the defect tip of the defect than the inner surface 200N of the ERW steel pipe 200, the reflected ultrasonic beam shown in FIG. ) And received by the receiving unit 124-2 earlier than the reflected ultrasonic beam shown in FIG.
When the ultrasonic beam (transmission wave) shown in FIG. 3-2 is transmitted to the electric resistance welded steel pipe 200 having the defect shown in FIG. 3-3 (a), it is shown in FIG. 3-3 (d). Thus, the received waveform obtained by synthesizing the received waveform of the reflected ultrasonic beam shown in FIG. 3-3 (b) and the received waveform of the reflected ultrasonic beam shown in FIG. 3-3 (c) is an actual reflected ultrasonic beam. Is received by the receiving unit 124-2 as a received waveform. The received waveform of the reflected ultrasonic beam shown in FIG. 3-3 (d) corresponds to a schematic diagram of the received waveform of the reflected ultrasonic beam shown in FIG.
For example, when there is no defect in the electric resistance welded pipe 200 shown in FIG. 3-3 (a), the reception waveform of the reflected ultrasonic beam shown in FIG. 3-3 (b) cannot be obtained. The reception waveform of the reflected ultrasonic beam received by the unit 124-2 is as shown in FIG.

FIG. 4 is a schematic diagram for explaining the defect inspection image generation processing by the defect inspection image generation unit 126 shown in FIG. 1 according to the embodiment of the present invention.
FIG. 4A shows the extracted waveform of the reflected ultrasonic beam shown in FIG. 3A that is extracted only during the period of 55.4 μs to 55.8 μs. Figure 4 (a), the reflected ultrasonic beam shown in FIG. 4 (a) and W _n, time and W _n (1) the amplitude of the reflected ultrasound beams W _n during 55.4Myuesu, thereafter _Let W _n (2),... _Be the amplitude value of the reflected ultrasonic beam W _n . Further, in FIG. 4, between the amplitude values of the reflected ultrasound beams W _n is the sampling period of the reflected ultrasonic beam W _n.

FIG. 4B shows a mesh structure including a plurality of meshes for forming a defect inspection image. This mesh structure provides a color based on the amplitude value of the reflected ultrasonic beam W _n when the ultrasonic beam propagates through the water interposed between the phased array probe 110 and the outer surface 200G of the ERW steel pipe 200. And a second mesh group 420 for imparting a color based on the amplitude value of the reflected ultrasonic beam W _n when the ultrasonic beam propagates through the interior of the ERW steel pipe 200. The mesh group in the leftmost column of the mesh structure shown in FIG. 4B has a color based on the amplitude value of the reflected ultrasonic beam W ₁ when the ultrasonic beam 112-1 shown in FIG. 1 is transmitted. The mesh group in the rightmost column of the mesh structure shown in FIG. 4B is set to the amplitude value of the reflected ultrasonic beam W _N when the ultrasonic beam 112-N shown in FIG. 1 is transmitted. Based on the color. That is, this mesh structure takes the position of the inner surface 200N of the ERW steel pipe 200 scanned by the ultrasonic beams 112-1 to 112-N in the horizontal direction (horizontal direction) which is the first direction, and the outside of the ERW steel pipe 200. The direction from the surface 200G toward the inner surface 200N is the vertical direction (more specifically, the vertical direction from top to bottom) as the second direction. In the second mesh group 420, the angle of the side surface of each mesh for each column is an angle corresponding to the refraction angle of the corresponding ultrasonic beam.

For example, if the amplitude values of the reflected ultrasound beams W _n shown in FIG. 4 (a) is obtained, the amplitude of the reflected ultrasound beams W _n shown in FIG. 4 (a), for example, the electric resistance welded steel pipe 200 Since this is the amplitude value of the reflected ultrasonic beam W _n when the ultrasonic beam propagates in the interior, as shown in FIG. 4B, the mesh group in the n th column is sequentially W _n (1). A color based on the amplitude value of W _n , a color based on the amplitude value of W _n (2),... Similarly, with respect to the amplitude value of the reflected ultrasonic beam W _n−1 , as shown in FIG. 4B, the mesh group of the ( _n− 1) -th column is sequentially assigned to W _n−1 (1). A color based on the amplitude value, a color based on the amplitude value of W _n-1 (2),... As described above, since the mesh structure shown in FIG. 4B is sequentially given in the vertical direction (column direction) the color based on the amplitude value of each reflected ultrasonic beam for each time, the vertical direction of the mesh structure is shown. The direction (more specifically, the direction from the top to the bottom) indicates the passage of time (more specifically, information related to the time when the reflected ultrasonic beam W _n is received by the receiving unit 124-2). It can be said. The mesh structure shown in FIG. 4B is the first in consideration of time information obtained from the distance between the phased array probe 110 and the outer surface 200G of the ERW steel pipe 200, the propagation speed of the ultrasonic beam, and the like. The mesh group 410 is provided with a color based on the amplitude value when the ultrasonic beam propagates through the water interposed between the phased array probe 110 and the outer surface 200G of the ERW steel pipe 200, The second mesh group 420 is set in advance by the defect inspection image generation unit 126 so that a color based on the amplitude value when the ultrasonic beam propagates through the ERW steel pipe 200 is given. .

  As described above, when a color based on each amplitude value of each reflected ultrasonic beam is given to the mesh structure shown in FIG. 4B, for example, a defect inspection image as shown in FIG. 4C is obtained. In the defect inspection image shown in FIG. 4C, the region below the position corresponding to the inner surface 200N of the ERW steel pipe 200 is not important and is partially omitted.

Here, it returns to description of FIG. 1 again.
The defect determination unit 127 illustrated in FIG. 1 determines whether a defect exists based on the defect inspection image generated by the defect inspection image generation unit 126. Specifically, the defect determination unit 127 includes a first white color and a first white color in the direction from the inner surface 200N to the outer surface 200G of the ERW steel pipe 200 in the defect inspection image generated by the defect inspection image generation unit 126. It is determined that there is a defect at a position where the second black appears after black and second white. In the defect inspection image shown in FIG. 4C, it is determined that a defect exists at the location indicated by the region 401. This defect determination can be described as follows using FIGS. 3-1 to 3-3.

In the present embodiment, the transmitter 124-1 transmits a transmission wave as shown in FIG. 3-2, and when there is no defect near the inner surface 200N of the ERW steel pipe 200, the inner surface 200N. The reflected ultrasonic beam reflected from the beam having the same waveform as the transmitted wave is received by the receiving unit 124-2.
In addition, when there is a defect near the inner surface 200N of the electric resistance welded steel pipe 200, the waveform of the reflected ultrasonic beam appears at the point of time B as described with reference to FIG. In this case, considering the defect inspection image shown in FIG. 4C, the second black color is shown as shown in FIG.

  In the waveform of the reflected ultrasonic beam shown in FIG. 3A, the direction from right to left corresponds to the direction from the inner surface 200N to the outer surface 200G of the ERW steel pipe 200. As described with reference to FIG. 3C, the amplitude value corresponding to the inner surface 200N is changed from the right to the left shown in FIG. The amplitude value is related to the amplitude value related to the second white color. If there is a defect in the vicinity of the inner surface 200N, next to the amplitude value related to the second white color (more specifically, before the amplitude value related to the second white color), An amplitude value related to the second black color appears.

Here, it returns to description of FIG. 1 again.
The defect size calculation unit 128 illustrated in FIG. 1 performs processing for calculating the size of a defect when the defect determination unit 127 determines that a defect exists. Specifically, the defect size calculation unit 128 corresponds to a position where the amplitude value of the reflected ultrasonic beam is maximum among positions where the first white appears in the defect inspection image generated by the defect inspection image generation unit 126. The time between the time and the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the second white appears is A (A in FIG. 3A), and the second black appears. The time corresponding to the position where the amplitude value of the reflected ultrasonic beam is the minimum value (that is, the highest black density) among the positions is B (B in FIG. 3A), and the defect is based on | A-B | Calculate the size of. Specifically, description will be made with reference to FIGS. 5 and 3-1.

FIG. 5 is a schematic diagram for explaining the defect size calculation processing by the defect size calculation unit 128 shown in FIG. 1 according to the embodiment of the present invention. FIG. 5 shows an enlarged view of the region 401 of the defect inspection image shown in FIG.
5 is formed with the mesh shown in FIG. 4B, the defect size calculation unit 128 first has a second black color corresponding to the defect inside the inner surface 200N as shown in FIG. 3-1. Extract the reflected ultrasonic beam that appears. Then, the defect size calculation unit 128 selects the reflected ultrasonic beam W _n (FIG. 3A) in which the second black color is most distant from the inner surface among the extracted reflected ultrasonic beams.
Next, in the selected reflected ultrasonic beam W _n , the defect size calculation unit 128 includes the time at the maximum amplitude value among the amplitude values corresponding to the first white color and the amplitude value corresponding to the second white color. A time intermediate between the time of the maximum amplitude value is A (A in FIG. 3A), and the time at the minimum amplitude value among the amplitude values corresponding to the second black color is B (B in FIG. 3A). ). Then, the defect size calculation unit 128 calculates the defect size S based on | A−B |.
More specifically, since the vertical direction (vertical direction) of the defect inspection image is information regarding the time of the reflected ultrasonic beam as shown in FIGS. 3A and 4, the defect size calculation unit 128 firstly determines | A The time Δt is obtained from −B |. Next, the defect size calculation unit 128 calculates the defect size S based on the time Δt and the sound speed of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the ERW steel pipe 200.

Here, it returns to description of FIG. 1 again.
The recording / display unit 129 shown in FIG. 1 records the defect inspection image generated by the defect inspection image generation unit 126, the defect determination result by the defect determination unit 127, the defect size calculation result by the defect size calculation unit 128, and the like. Or display. Furthermore, the recording / display unit 129 performs a process of recording and displaying various data and various information as necessary.

  Next, a processing procedure of the defect inspection method by the defect inspection apparatus 100 according to the present embodiment will be described.

  FIG. 6 is a flowchart showing an example of a processing procedure of the defect inspection method by the defect inspection apparatus 100 according to the embodiment of the present invention. The description of the flowchart shown in FIG. 6 will be made using the configuration of the defect inspection apparatus 100 shown in FIG. In starting the processing of the flowchart shown in FIG. 6, it is assumed that the subject condition is input by the subject condition input unit 121 and the transmission / reception condition is set by the transmission / reception condition setting unit 122 in advance. .

  First, in step S101, the transmission / reception control unit 123 sets the focal point position number n of the inner surface 200N of the ERW steel pipe 200 from n = 1 to n = N, and the number of channels to be transmitted / received (the ultrasonic transducer 111 to be transmitted / received). Number) M (the same value for each focusing point position n) is set. Here, 1 to N in the focal point position number n of the inner surface 200N of the electric resistance steel pipe 200 correspond to the scanning direction indicated on the inner surface 200N of the electric resistance steel pipe 200 shown in FIG.

  Subsequently, in step S102, the transmission / reception control unit 123 sets 1 to the number n indicating the focal point position of the ultrasonic beam to be transmitted.

  Subsequently, in step S103, the transmission unit 124-1 performs a process of transmitting the ultrasonic beam 112-n by the M ultrasonic transducers 111 to the focus point position of the number n. Next, the receiving unit 124-2 performs processing for receiving the ultrasonic beam 112-n reflected by the same M ultrasonic transducers 111 as a reflected ultrasonic beam.

Subsequently, in step S104, the reception signal processing unit 125 adds the M received signals received via the M numbers of ultrasonic transducers 111 in step S103, 1 single combined received signal (W _n) To do. This is referred to as the reflected ultrasonic beam W _n.

  Subsequently, in step S105, the transmission / reception control unit 123 determines whether or not the number n indicating the focal point position of the ultrasonic beam to be transmitted is smaller than N. As a result of this determination, if the number n indicating the focal point position of the ultrasonic beam to be transmitted is smaller than N (S105 / YES), all the focal point positions set in step S101 are not yet obtained. It determines with not transmitting the ultrasonic beam, and progresses to step S106.

  In step S106, the transmission / reception control unit 123 adds 1 to the number n indicating the focal point position of the transmission target ultrasonic beam to change the number n indicating the focal point position of the transmission target ultrasonic beam. . And the process after step S103 is performed again about the number n which shows the focus point position of the ultrasonic beam of the transmission object changed.

On the other hand, as a result of the determination in step S105, when the number n indicating the focus point position of the ultrasonic beam to be transmitted is N or more (S105 / NO), all the focus point positions set in step S101 are focused. It is determined that the ultrasonic beam has been transmitted for the point position, and the process proceeds to step S107. Incidentally, so that when the process proceeds to step S107, the reflected ultrasonic beam W ₁ to W-waveform of N reflected ultrasound beams to _N are gathered.

In step S107, the defect inspection image generating unit 126 sets 1 to the number n of the reflected ultrasound beams W _n to be processed.

Subsequently, in step S108, the defect inspection image generating unit 126 performs reflection amplitude value data of the ultrasound beam W _n, the process of assigning on the center locus of the ultrasonic beam 112-n of the number n. For example, the defect inspection image generation unit 126 assigns the amplitude value data of the reflected ultrasonic beam W ₁ to the central locus 112-1C of the ultrasonic beam 112-1 number 1 shown in FIG. The amplitude value data of W _C (1 <C <N) is assigned on the central locus 112-CC of the ultrasonic beam 112-C shown in FIG. 1, and the amplitude value data of the reflected ultrasonic beam W _N is shown in FIG. 1 is assigned on the central locus 112-NC of the ultrasonic beam 112-N of number N shown in FIG.

Subsequently, in step S109, the defect inspection image generation unit 126 gives a color based on the amplitude value data of the reflected ultrasonic beam W _n to the mesh for forming the defect inspection image. Specifically, as described above with reference to FIGS. 3A and 3B, based on the relationship between the amplitude value and the color gradation shown in FIG. 3A, the mesh structure shown in FIG. , impart color based on the amplitude value data of the reflected ultrasonic beam W _n.

Subsequently, in step S110, the defect inspection image generating unit 126, the number n of the reflected ultrasound beams W _n to be processed is determined whether N is less than. If the number _n in the reflected ultrasonic beam W _{n to be} processed is smaller than N as a result of this determination (S110 / YES), the reflected ultrasonic beams W _{1 to} W _N collected through the processing of steps S102 to S106. It is determined that the processing has not yet been performed for all the reflected ultrasonic beams, and the process proceeds to step S111.

In step S111, the defect inspection image generating unit 126 adds 1 to the number n of the reflected ultrasound beams W _n to be processed, changing the number n of the reflected ultrasound beams W _n to be processed. Then, the number n of the reflected ultrasound beams W _n to be processed was changed, performs step S108 and subsequent processing again.

On the other hand, _if the number _n in the reflected ultrasonic beam Wn to be processed is greater than or equal to N as a result of the determination in step S110 (S110 / NO), the reflected ultrasonic beam collected through the processing in steps S102 to S106. It is determined that processing has been performed for all reflected ultrasonic beams of W _{1 to} W _{N, and} the process proceeds to step S112. When proceeding to step S112, for example, a color based on the amplitude value data of all the reflected ultrasonic beams W _{1 to} W _N is given to the mesh structure shown in FIG. 4B, For example, a defect inspection image as shown in FIG. 4C is generated.

  Subsequently, in step S <b> 112, the defect determination unit 127 determines whether or not a defect exists based on the defect inspection image generated by the defect inspection image generation unit 126. Specifically, the defect determination unit 127 includes a first white color and a first white color in the direction from the inner surface 200N to the outer surface 200G of the ERW steel pipe 200 in the defect inspection image generated by the defect inspection image generation unit 126. It is determined that there is a defect at a position where the second black appears after black and second white. In the defect inspection image shown in FIG. 4C, it is determined that a defect exists at the location indicated by the region 401.

  Subsequently, in step S113, the defect size calculation unit 128 determines whether or not there is a defect in the defect determination in step S112. As a result of this determination, when it is determined that there is a defect in the defect determination in step S112 (S113 / YES), the process proceeds to step S114.

In step S114, the defect size calculation unit 128 determines, in the defect inspection image generated by the defect inspection image generation unit 126, the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the first white appears. An intermediate time between the corresponding time and the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the second white appears is A (A in FIG. 3A), and the second black The time corresponding to the position where the amplitude value of the reflected ultrasonic beam is a minimum value among the positions where the noise appears is B (B in FIG. 3A), and the size of the defect is calculated based on | A−B |.
As described above, FIG. 5 shows an enlarged view of the defect area 401 of the defect inspection image shown in FIG. As described above, FIG. 5 is formed by the mesh shown in FIG. 4B, and the vertical direction (vertical direction) relates to the time of the reflected ultrasonic beam as shown in FIGS. Information.
The defect size calculation unit 128 first extracts a reflected ultrasonic beam in which a second black color corresponding to the defect appears inside the inner surface 200N as shown in FIG. Then, the defect size calculation unit 128 selects the reflected ultrasonic beam W _n (FIG. 3A) in which the second black color is most distant from the inner surface among the extracted reflected ultrasonic beams.
Next, the defect size calculation unit 128 determines the time corresponding to the maximum amplitude value among the amplitude values corresponding to the first white color and the amplitude corresponding to the second white color in the reflected ultrasonic beam W _n shown in FIG. A time that is intermediate to the time of the maximum amplitude value among the values is A (corresponding to the point A in FIG. 5), and the time at the minimum amplitude value of the amplitude values corresponding to the second black color is B ( (Corresponding to the point B in FIG. 5). Then, the defect size calculation unit 128 calculates the defect size S based on | A−B |. At this time, since the vertical direction (vertical direction) of the defect inspection image is information on the time of the reflected ultrasonic beam as shown in FIGS. 3A and 4B, the defect size calculation unit 128 first determines | A− Time Δt is obtained from B |. Next, the defect size calculation unit 128 calculates the defect size S based on the time Δt and the sound speed of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the ERW steel pipe 200. Specifically, the defect size calculation unit 128 calculates the defect size S by calculating S = (sonic velocity of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the electric resistance welded pipe 200) × (time Δt) ÷ 2. calculate. Here, the reason for dividing by 2 is that the time Δt is an amount corresponding to the reciprocation time of the ultrasonic beam, and is calculated as a one-way time.

  When the process of step S114 is completed, or when it is determined that there is no defect in step S113 (S113 / NO), the process proceeds to step S115.

In step S115, the recording / display unit 129 displays the defect inspection image generated by the defect inspection image generation unit 126, the defect determination result by the defect determination unit 127 in step S112, and the defect by the defect size calculation unit 128 in step S114. Processing for recording or displaying the size calculation result or the like is performed. If it is determined in step S113 that there is no defect and the defect size calculation processing by the defect size calculation unit 128 in step S114 is not performed, the result is not recorded or displayed.
Thereafter, the process of the flowchart of FIG.

  By obtaining the processes of steps S101 to S115 described above, the process of the defect inspection method by the defect inspection apparatus 100 according to the present embodiment is completed.

[Example]
Next, specific examples based on the above-described embodiment of the present invention will be described.

FIG. 7 is a diagram showing an example of the embodiment according to the present invention and showing a sample of the electric resistance welded steel pipe 200 used for defect inspection.
Specifically, the first sample steel pipe 200-1 shown in FIG. 7A has a diameter of 102 mm, a pipe thickness of 3.4 mm, and a length in the pipe axis direction of 300 mm. In addition, in the 1st sample steel pipe 200-1 shown to Fig.7 (a), the position of the left end surface of a pipe-axis direction is set to X = 0mm, and the position of the right end surface of a pipe-axis direction is set to X = 300mm. Set.
The second sample steel pipe 200-2 shown in FIG. 7B has a diameter of 102 mm, a pipe thickness of 3.4 mm, and a length in the pipe axis direction of 600 mm. In the second sample steel pipe 200-2 shown in FIG. 7B, the X coordinate system in which the position of the left end surface in the tube axis direction is X = 0 mm and the position of the right end surface in the tube axis direction is X = 600 mm. Set.

  FIG. 8 is a diagram for explaining a defect inspection test using a water immersion point focused flaw detector, which was performed on the first sample steel pipe 200-1 shown in FIG. 7A.

  FIG. 8A shows the first sample steel pipe 200-1 shown in FIG. Here, in the first sample steel pipe 200-1 shown in FIG. 8A, the X coordinate where the position of the left end surface in the tube axis direction is X = 0 mm and the position of the right end surface in the tube axis direction is X = 300 mm. The system is set.

  In the first sample steel pipe 200-1 shown in FIG. 8 (a), a 45 ° oblique angle flaw detection is performed using the water immersion point converging probe shown in FIG. 8 (c) in the range of X = 70 mm to X = 230 mm. Defect inspection was performed. This defect inspection is a test for confirming the position of the defect in the first sample steel pipe 200-1, and was performed by setting the frequency of the ultrasonic beam transmitted from the water immersion point focused flaw detector to 50 MHz. Further, in the defect inspection using the water immersion point converging probe shown in FIG. 8C, the first sample steel pipe 200-1 is rotated ± 5 ° in the circumferential direction of the outer peripheral surface 200G around the welded portion 210. Scanned. FIG. 8B shows a C-scan image obtained as a result of this defect inspection test. In the C scan image shown in FIG. 8B, the horizontal axis represents the X coordinate system (X = 70 mm to X = 230 mm), and the vertical axis represents the scan rotation range (−5 ° to + 5 °). Further, in the C-scan image shown in FIG. 8B, a white portion is a portion detected as a defect. Here, the C scan image is a name generally used at the time of ultrasonic flaw detection, and a two-dimensional position of a subject to be flaw detected and an ultrasonic reception signal in the depth direction at the position. The maximum value is displayed, and the distribution of defects two-dimensionally projected is shown. This method using the 50 MHz high frequency water immersion point flaw detector can detect minute defects because of its high resolution. However, in order to detect the welded portion 210, the ERW steel pipe 200 is moved in the circumferential direction. Therefore, it is difficult to put the probe into practical use online.

  Next, an experiment using the defect inspection method according to the present invention was performed on the first sample steel pipe 200-1 shown in FIGS. 7 (a) and 8 (a).

  FIG. 9 shows an example of the embodiment according to the present invention. The phased array probe 110 shown in FIGS. 1 and 2 and the first sample steel pipe 200 shown in FIGS. 7 (a) and 8 (a). It is a figure which shows the positional relationship with -1. In the experiment shown in FIG. 9, the distance (underwater propagation distance) between the phased array probe 110 and the welded portion 210 on the outer surface 200G of the first sample steel pipe 200-1 was set to 40 mm. Further, in the experiment shown in FIG. 9, the case where the center position of the phased array probe 110 comes on the center position of the welded portion 210 of the first sample steel pipe 200-1 is defined as 0 ° in the circumferential direction of the outer peripheral surface 200G. The range from −9.0 ° to + 9.0 ° was scanned in increments of 1.5 °. Specifically, the experiment was performed by rotating the first sample steel pipe 200-1 in the circumferential direction of the outer peripheral surface 200G in a range of −9.0 ° to + 9.0 °.

FIG. 10 shows an example of the embodiment according to the present invention, and is a diagram showing a defect inspection image obtained by the experiment shown in FIG.
Here, FIG. 10A shows a defect inspection image in the case of −9.0 °, FIG. 10B shows a defect inspection image in the case of −7.5 °, and FIG. Shows a defect inspection image at −6.0 °, FIG. 10 (d) shows a defect inspection image at −4.5 °, and FIG. 10 (e) shows −3.0 °. FIG. 10 (f) shows a defect inspection image in the case of −1.5 °, FIG. 10 (g) shows a defect inspection image in the case of 0 °, and FIG. h) shows a defect inspection image at + 1.5 °, FIG. 10 (i) shows a defect inspection image at + 3.0 °, and FIG. 10 (j) shows a case at + 4.5 °. FIG. 10 (k) shows a defect inspection image at + 6.0 °, FIG. 10 (l) shows a defect inspection image at + 7.5 °, and FIG. m) is +9.0 Shows a defect inspection image when the.

  In the experiment shown in FIG. 9, as shown in FIG. 10, a change in the inner surface response was observed in the range of −6.0 ° to + 7.5 ° in the circumferential direction of the outer peripheral surface 200G. Deformation and discrepancy were observed as changes in the inner surface response. As shown in FIG. 10, the change in the inner surface response varies, but on the other hand, it has a characteristic that it can be observed over a wide range. This indicates that there is a possibility that the defect can be evaluated without rotating the first sample steel pipe 200-1.

  FIG. 11 shows an example of the embodiment according to the present invention. In the positional relationship between the −4.5 ° phased array probe 110 and the first sample steel pipe 200-1 shown in FIG. It is a figure explaining the experiment using the defect inspection method which concerns.

  FIG. 11A is a C scan image obtained by extracting a range including X = 85 mm to X = 169 mm from the C scan image shown in FIG. The C scan image shown in FIG. 11A shows that a defect is considered to exist in a white portion as in the C scan image shown in FIG.

  FIG. 11B is a diagram showing the positional relationship between the phased array probe 110 and the first sample steel pipe 200-1 in this experiment. The phased array probe 110 and the first sample steel pipe 200-1 are shown in FIG. It is shown that the experiment was conducted with the relative angle θr to −4.5 ° fixed.

  FIG.11 (c) is a figure which shows the defect inspection image produced | generated using the defect inspection method which concerns on this invention in the point of X = 85mm of the 1st sample steel pipe 200-1 shown to Fig.8 (a). . Moreover, FIG.11 (d) is a figure which shows the defect inspection image produced | generated using the defect inspection method which concerns on this invention in the point of X = 99mm of the 1st sample steel pipe 200-1 shown to Fig.8 (a). It is. Moreover, FIG.11 (e) is a figure which shows the defect inspection image produced | generated using the defect inspection method which concerns on this invention in the point of X = 169mm of the 1st sample steel pipe 200-1 shown to Fig.8 (a). It is. In the experiments shown in FIG. 11C to FIG. 11E, the focal depth of the ultrasonic beam to be transmitted is fixed to the inner surface 200N of the first sample steel pipe 200-1 at each point. Scanning was performed in 0.5 ° increments with the focusing angle in the scanning of the ultrasonic beam along the surface 200N in the range of −45 ° to + 45 °.

  Defects were detected from the defect inspection images shown in FIGS. 11 (c) and 11 (e). Further, no defect was detected from the defect inspection image shown in FIG. The experimental results shown in FIGS. 11C to 11E are based on the defect detection results shown in FIG. 11A, and the defect inspection using the defect inspection method according to the present invention is effective. I found out.

Next, the effect of vibration that could occur in an actual production line was verified.
In an actual production line, the relative distance between the phased array probe 110 and the ERW steel pipe 200 may change by about ± 0.5 mm due to the influence of vibration. Therefore, in FIG. 9, the position of the phased array probe 110 is moved ± 1.0 mm in the Y direction and the Z direction, and defect inspection is performed using the defect inspection method according to the present invention.

FIG. 12 shows an example of the embodiment according to the present invention. In FIG. 9, the defect obtained by the defect inspection method according to the present invention by moving the position of the phased array probe 110 by ± 1.0 mm in the Y direction. It is a figure which shows a test | inspection image.
Here, FIG. 12A shows a defect inspection image when the phased array probe 110 is moved by −1.0 mm in the Y direction, and FIG. 12B shows the phased array probe 110 in the Y direction. FIG. 12C shows a defect inspection image when moved by −0.5 mm, FIG. 12C shows a defect inspection image when the phased array probe 110 is moved 0 mm in the Y direction, and FIG. FIG. 12E shows a defect inspection image when the phased array probe 110 is moved +0.5 mm in the Y direction. FIG. 12E shows a defect inspection image when the phased array probe 110 is moved +1.0 mm in the Y direction. Is shown.
In the defect inspection images shown in FIGS. 12A to 12E, positions corresponding to the inner surface are shifted. This is because the mesh structure shown in FIG. 4B set in the defect inspection image generation unit 126 is set even when the defect inspection is performed by moving the position of the phased array probe 110 ± 1.0 mm in the Y direction. This is because the time setting in the vertical direction is not changed. That is, when the phased array probe 110 is moved by −1.0 mm in the Y direction, the phased array probe 110 and the ERW steel pipe are compared with the case where the phased array probe 110 is moved by 0 mm in the Y direction. Since the relative distance to 200 becomes longer, the propagation time of the ultrasonic beam also becomes longer. As a result, the position corresponding to the inner surface is located below. For the same purpose, when the phased array probe 110 is moved +1.0 mm in the Y direction, the phased array probe 110 is electrically connected to the phased array probe 110 compared to the case where the phased array probe 110 is moved 0 mm in the Y direction. Since the relative distance to the sewn steel pipe 200 is shortened, the propagation time of the ultrasonic beam is also shortened, and as a result, the position corresponding to the inner surface is located upward.

FIG. 13 shows an example of the embodiment according to the present invention. In FIG. 9, the defect obtained by the defect inspection method according to the present invention by moving the position of the phased array probe 110 by ± 1.0 mm in the Z direction. It is a figure which shows a test | inspection image.
Here, FIG. 13A shows a defect inspection image when the phased array probe 110 is moved by −1.0 mm in the Z direction, and FIG. 13B shows the phased array probe 110 in the Z direction. Fig. 13 (c) shows a defect inspection image when the phased array probe 110 is moved 0mm in the Z direction, and Fig. 13 (d) shows a defect inspection image when the phase array probe 110 is moved 0mm in the Z direction. A defect inspection image when the phased array probe 110 is moved by +0.5 mm in the Z direction is shown. FIG. 13E shows a defect inspection image when the phased array probe 110 is moved by +1.0 mm in the Z direction. Is shown.

  As shown in FIG. 12 and FIG. 13, since the defect was detected from any defect inspection image, even if the relative distance between the phased array probe 110 and the ERW steel pipe 200 changed due to the influence of vibration, It has been found that the defect inspection using the defect inspection method according to the present invention is effective.

  Next, it verified about the applicability in consideration of the pipe making speed in the ERW steel pipe 200 of an actual production line.

Since a typical pipe forming speed in the electric resistance welded steel pipe 200 in an actual production line is several hundred mm / s, it was verified whether it can be accommodated. The maximum repetition frequency in the general phased array probe 110 is about 10 kHz.
When scanning is performed in increments of 0.5 ° with the focusing angle in the scanning of the ultrasonic beam along the inner surface 200N in the range of −45 ° to + 45 °, 181 times of ultrasonic waves are used to generate one defect inspection image. It is necessary to transmit and receive a beam. In this case, since it takes 181 (times) / 10000 (Hz) = 0.0181 (s) to generate one defect inspection image, assuming that the pipe making speed is 800 mm / s, one defect inspection image During the generation, the ERW steel pipe 200 advances by 14.4 mm.

  Therefore, for example, if the scanning angle of the ultrasonic beam along the inner surface 200N is limited to a range of ± 5 ° and scanning is performed in increments of 1.0 °, one defect inspection image is generated. , It is necessary to transmit and receive the ultrasonic beam 11 times. In this case, since it takes 11 (times) / 10000 (Hz) = 0.0011 (s) to generate one defect inspection image, assuming that the pipe making speed is 800 mm / s, one defect inspection image During generation, the ERW steel pipe 200 will travel 0.8 mm. Therefore, in this case, a minute defect having a length of about 1 mm in the tube axis direction of the ERW steel tube 200 can be detected.

  Next, the defect according to the present invention is determined using the second sample steel pipe 200-2 shown in FIG. 7 (b) after considering the pipe making speed in the above-mentioned actual production line of the ERW steel pipe 200. An experiment using the inspection method was conducted.

  FIG. 14 shows an example of the embodiment according to the present invention, and shows an experimental result using the defect inspection method according to the present invention using the second sample steel pipe 200-2 shown in FIG. 7B. FIG.

FIG. 14A shows that the moving speed of the second sample steel pipe 200-2 is 400 mm / s, and the vicinity of the inner surface 200N (time t = 55.0 μs to 55.9 μs shown in FIG. 3-1) is in the tube axis direction. in the fast scan, an image showing a two-dimensional map of the reflected ultrasound beams W _n. Here, _n of the reflected ultrasonic beam Wn is a constant of 1 or more and N or less. Moreover, Fig.14 (a) extracts the range containing X = 68mm-X = 468mm of the 2nd sample steel pipe 200-2 from the image which scanned the pipe axis direction of the 2nd sample steel pipe 200-2 at high speed. It is an image.
FIG. 14B is an enlarged view of the image area 1401 shown in FIG.

  From the images shown in FIGS. 14A and 14B, it was confirmed that the inner surface response fluctuated due to the influence of the vibration of the phased array probe 110 during scanning. However, in spite of such fluctuations in the inner surface response, a dark portion (second black) having a length of about 40 mm is characterized at a time earlier than the second peak (second white) of the inner surface response. The defect response was confirmed.

Further, in the image shown in FIG. 14B, the defect depth (that is, the defect size S) was calculated as follows.
First, a time intermediate between the time corresponding to the first peak (first white) of the inner surface response and the time corresponding to the second peak (second white) of the inner surface response is defined as time A, and the second The time corresponding to the position _where the amplitude value of the reflected ultrasonic beam Wn is the minimum value is the time B. The time Δt was obtained from | A−B | and was 0.15 μs. When the sound velocity of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the electric resistance welded pipe 200 was 5900 m / s, the defect depth (that is, the defect size S) was calculated to be about 0.44 mm. Since the actual defect size detected by observing the cross section is usually about 0.2 mm to 1.0 mm, this experimental result is considered to be a reasonable result.

  Next, a processing procedure of the defect size calculation method in the experiment shown in FIG. 14 will be described.

  FIG. 15 is a flowchart illustrating an example of a processing procedure of the defect size calculation method in the experiment illustrated in FIG. 14 according to the embodiment of the present invention.

First, in step S201, the defect inspection image generating unit 126 (or the defect size calculation unit 128) generates a two-dimensional map of the reflected ultrasound beams W _n. Specifically, an image showing a two-dimensional map of the reflected ultrasonic beam W _n shown in FIG.

  Subsequently, in step S202, the defect determination unit 127 (or the defect size calculation unit 128) extracts a portion (defect) that is disturbed near the inner surface echo in the two-dimensional map generated in step S201. Specifically, in the direction from the inner surface 200N to the outer surface 200G of the second sample steel pipe 200-2, a portion in which the second black appears after the first white, the first black, and the second white. Are extracted as defects.

  Subsequently, in step S203, the defect size calculator 128 detects a time A at which the inner surface echo exists. Specifically, as shown in FIG. 14B, here, the time corresponds to the first peak (first white) of the inner surface response and the second peak (second white) of the inner surface response. A time that is intermediate to the time to be set is time A.

Subsequently, in step S204, the defect size calculation unit 128 is a time earlier than the inner surface echo is present, the amplitude value of the reflected ultrasonic beam W _n detects the time B is the minimum value. Here, time B shown in FIG. 14B is detected.

  Subsequently, in step S205, the defect size calculation unit 128 obtains the time Δt from | A−B |.

Subsequently, in step S206, the defect size calculation unit 128 calculates the defect size S based on the time Δt and the sound velocity of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the second sample steel pipe 200-2. To do. Specifically, the defect size calculation unit 128 calculates S = (sonic velocity of the ultrasonic beam (reflected ultrasonic beam) in the steel material of the second sample steel pipe 200-2) × (time Δt) / 2. The defect size S is calculated. Here, the reason for dividing by 2 is that the time Δt is an amount corresponding to the reciprocation time of the ultrasonic beam, and is calculated as a one-way time.
Then, the process of the flowchart of FIG. 15 is complete | finished.

  By obtaining the above steps S201 to S206, the defect size calculation method in the experiment shown in FIG. 14 is completed.

According to the embodiment of the present invention, the defect inspection is performed using the ultrasonic beam that is incident from the welded portion 210 on the outer surface 200G of the ERW steel pipe 200 and scans the vicinity of the inner surface 200N of the ERW steel pipe 200. Since the propagation distance of the ultrasonic beam in the electric resistance welded pipe 200 can be shortened, attenuation of the ultrasonic beam can be suppressed, and as a result, a minute defect can be detected.
In the embodiment of the present invention, the received waveform of the reflected ultrasonic beam reflected by the defect shown in FIG. 3B is a minute signal because the defect tip of the defect is small. Therefore, the time B can be detected by detecting the local minimum value of the amplitude value of the reflected ultrasonic beam. Then, by calculating the size of the defect using | A−B |, the size of the defect is small, and the received waveform of the reflected ultrasonic beam reflected by the defect shown in FIG. The size of the defect can be calculated even if the received waveform of the reflected ultrasonic beam reflected by the inner surface 200N shown in FIG. For example, in the technique of the above-mentioned Patent Document 3, since it is necessary to use a reception waveform that is completely separated in time, it is difficult to detect a defect of, for example, 0.5 mm or less. According to the above, it becomes possible to detect a defect of 0.5 mm or less, for example.

(Other embodiments)
In the above-described embodiment of the present invention, as illustrated in FIG. 1, the defect inspection apparatus 100 has been described with respect to an example in which a defect included in the welded portion 210 of the ERW steel pipe 200 is inspected. The invention is not limited to this form. For example, in addition to the defect contained in the welding part 210, the form which test | inspects the defect in the non-welding part of the ERW steel pipe 200 is also contained in this invention. In this case, for example, the transmission unit 124-1 shown in FIG. A configuration is adopted in which an ultrasonic beam 112 that is scanned while changing the focal point along the inner surface 200N is transmitted from the phased array probe 120.

Further, the time waveform of the ultrasonic beam transmitted from the transmission unit 124-1 is not limited to the waveform of FIG. 3-2, and has a positive or negative first local peak. What is necessary is just to have a 2nd local peak of the polarity opposite to a 1st local peak, and also to have the 3rd local peak of the same polarity as the said 1st local peak after that.
Therefore, the waveform of FIG. 3-2 has a waveform obtained by reversing the polarity, that is, having a first local peak with a negative polarity, followed by a second local peak with a positive polarity, and then Or a waveform having a third local peak of negative polarity. When this ultrasonic beam is transmitted from the transmission unit 124-1, the reception waveform of the reflected ultrasonic beam received by the reception unit 124-2 is also opposite in amplitude value to the reception waveform shown in FIG. It will become. That is, in this example, the first white color shown in FIG. 3A becomes “first black”, the first black color shown in FIG. 3A becomes “first white”, and FIG. The second white color shown becomes “second black color”, and the second black color shown in FIG. 3A becomes “second white color”. In the case of this example, the defect determination unit 127 includes “first black”, “first white”, “in the direction from the inner surface 200N to the outer surface 200G of the ERW steel pipe 200 in the defect inspection image. A mode is adopted in which it is determined that a defect is present at a position where “second white” appears after “second black”. In the case of this example, when the defect size determination unit 127 determines that there is a defect in the defect determination unit 127, the amplitude value of the reflected ultrasonic beam in the position where “first black” appears in the defect inspection image. A is the intermediate time between the time corresponding to the position where the second ultrasonic black beam appears and the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is minimum among the positions where the “second black” appears. The time corresponding to the position where the amplitude value of the reflected ultrasonic beam is the maximum among the positions where “white” appears is B, and the defect size is calculated based on | A−B |.

The present invention can also be realized by executing the following processing.
That is, software (program) that realizes the function of the control processing device 120 of the above-described embodiment of the present invention is supplied to a system or device via a network or various storage media, and a computer (or CPU or CPU) of the system or device is supplied. MPU or the like) reads out and executes a program. This program and a computer-readable recording medium storing the program are included in the present invention.

  The above-described embodiments of the present invention are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be construed in a limited manner. . That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

100: Defect inspection device, 110: Phased array probe, 111: Ultrasonic transducer, 112-1 to 112-N: Ultrasonic beam, 120: Control processing device, 121: Subject condition input unit, 122: Transmission / reception Condition setting unit, 123: Transmission / reception control unit, 124-1: Transmission unit, 124-2: Reception unit, 125: Reception signal processing unit, 126: Defect inspection image generation unit, 127: Defect determination unit, 128: Defect size calculation Part, 129: recording / display part, 200: ERW steel pipe, 200G: outer surface, 200N: inner surface, 210: welded part

Claims (20)

A defect inspection device for inspecting defects contained in a welded steel pipe in which a weld is formed in the pipe axis direction,
A phased array probe installed outside the outer surface of the welded steel pipe and arranged with a plurality of ultrasonic transducers;
An ultrasonic beam that enters from the outside of the welded portion on the outer surface of the welded steel pipe and scans at least the welded portion in the vicinity of the inner surface of the welded steel pipe in the circumferential direction while changing a focusing point along the inner surface. Transmitting means for transmitting from the phased array probe;
Receiving means for receiving the reflected ultrasonic beam as a reflected ultrasonic beam via the phased array probe;
A defect inspection image based on the amplitude value of the reflected ultrasonic beam is generated by taking the position of the scanned inner surface in the first direction and taking the direction from the outer surface of the welded steel pipe to the inner surface as the second direction. Defect inspection image generation means ;
Defect determination means for determining whether or not a defect exists based on the defect inspection image generated by the defect inspection image generation means ,
The time waveform of the ultrasonic beam transmitted from the transmitting means has a first local peak that is positive or negative, and then has a second local peak having a polarity opposite to that of the first local peak. , further followed, a third local peaks of the same polarity as the first local peak, the absolute value of the second local peak of the absolute value of the three local peaks most rather large,
The defect determination means includes
Of the region of the defect inspection image generated by the defect inspection image generating means, the time waveform of the ultrasonic beam received by the receiving means has a first local peak that is positive or negative, and then the first Determining that there is no defect in a region having a second local peak having a polarity opposite to that of the first local peak and then having a third local peak having the same polarity as the first local peak;
Of the region of the defect inspection image generated by the defect inspection image generating means, the time waveform of the ultrasonic beam received by the receiving means has a first local peak that is positive or negative, and then the first A second local peak having a polarity opposite to that of the first local peak, followed by a third local peak having the same polarity as the first local peak, and further thereafter, the first local peak A defect inspection apparatus that determines that a defect exists in a region having a fourth local peak having a polarity opposite to that of a peak .   The defect inspection apparatus according to claim 1, wherein the first local peak is positive.   The defect inspection apparatus according to claim 1, wherein the first local peak is negative. When generating the defect inspection image, the defect inspection image generation means sets the color of the position where the amplitude value of the reflected ultrasonic beam is larger than the positive first threshold value to white, and the reflected ultrasonic beam The color of the position where the amplitude value is smaller than the negative second threshold smaller than the first threshold is black,
In the defect inspection image, the defect determination means includes a first white color, a first black color, a second white color, and a second black color in a direction from the inner surface to the outer surface of the welded steel pipe. The defect inspection apparatus according to claim 2, wherein the defect is determined to be present at a position where the defect appears. When generating the defect inspection image, the defect inspection image generation means sets the color of the position where the amplitude value of the reflected ultrasonic beam is larger than the positive first threshold value to white, and the reflected ultrasonic beam The color of the position where the amplitude value is smaller than the negative second threshold smaller than the first threshold is black,
In the defect inspection image, the defect determination means includes a first black color, a first white color, a second black color, and a second white color in a direction from the inner surface to the outer surface of the welded steel pipe. The defect inspection apparatus according to claim 3, wherein it is determined that the defect exists at a position where the defect appears. In the defect inspection image, the second direction indicates information related to the time when the reflected ultrasonic beam is received by the receiving unit,
In the defect inspection image, the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the first white appears and the position of the reflected ultrasonic beam among the positions where the second white appears. A time intermediate between the time corresponding to the position where the amplitude value is maximum is A, and B is the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is minimum among the positions where the second black appears. 5. The defect inspection apparatus according to claim 4, further comprising defect size calculating means for calculating the size of the defect based on | A-B |. In the defect inspection image, the second direction indicates information related to the time when the reflected ultrasonic beam is received by the receiving unit,
In the defect inspection image, the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is minimum among the positions where the first black appears and the position of the reflected ultrasonic beam among the positions where the second black appears. A time intermediate between the time corresponding to the position where the amplitude value is minimum is A, and B is the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the second white appears. The defect inspection apparatus according to claim 5, further comprising a defect size calculating unit that calculates the size of the defect based on | A−B |.   8. The defect inspection image generation unit generates the defect inspection image by allocating an amplitude value of the reflected ultrasonic beam on a central locus of the ultrasonic beam. The defect inspection apparatus according to item.   The defect inspection apparatus according to claim 1, further comprising display means for displaying the defect inspection image. A defect that is installed outside the outer surface of a welded steel pipe in which a weld is formed in the pipe axis direction, includes a phased array probe in which a plurality of ultrasonic transducers are arranged, and inspects a defect contained in the welded steel pipe A defect inspection method using an inspection apparatus,
An ultrasonic beam that enters from the outside of the welded portion on the outer surface of the welded steel pipe and scans at least the welded portion in the vicinity of the inner surface of the welded steel pipe in the circumferential direction while changing a focusing point along the inner surface. Transmitting from the phased array probe;
Receiving the reflected ultrasonic beam as a reflected ultrasonic beam via the phased array probe;
A defect inspection image based on the amplitude value of the reflected ultrasonic beam is generated by taking the position of the scanned inner surface in the first direction and taking the direction from the outer surface of the welded steel pipe to the inner surface as the second direction. A defect inspection image generation step ;
A defect determination step for determining whether a defect exists based on the defect inspection image generated by the defect inspection image generation step ,
The time waveform of the ultrasonic beam transmitted in the transmission step has a first local peak that is positive or negative, and then has a second local peak having a polarity opposite to the first local peak, further subsequently, a third local peaks of the same polarity as the first local peak, the absolute value of the second local peak of the absolute value of the three local peaks most rather large,
The defect determination step includes:
Of the region of the defect inspection image generated by the defect inspection image generation step, the time waveform of the ultrasonic beam received at the reception step has a positive or negative first local peak, and then the first Determining that there is no defect in a region having a second local peak having a polarity opposite to that of the first local peak and then having a third local peak having the same polarity as the first local peak;
Of the region of the defect inspection image generated by the defect inspection image generation step, the time waveform of the ultrasonic beam received at the reception step has a positive or negative first local peak, and then the first A second local peak having a polarity opposite to that of the first local peak, followed by a third local peak having the same polarity as the first local peak, and further thereafter, the first local peak A defect inspection method characterized by determining that a defect is present in a region having a fourth local peak having a polarity opposite to that of the peak .   The defect inspection method according to claim 10, wherein the first local peak is positive.   The defect inspection method according to claim 10, wherein the first local peak is negative. In the defect inspection image generation step, when generating the defect inspection image, the color of the position where the amplitude value of the reflected ultrasonic beam is larger than the positive first threshold is white, and the reflected ultrasonic beam The color of the position where the amplitude value is smaller than the negative second threshold smaller than the first threshold is black,
In the defect inspection step, in the defect inspection image, a second black is next to the first white, the first black, and the second white in a direction from the inner surface to the outer surface of the welded steel pipe. The defect inspection method according to claim 11, wherein it is determined that the defect exists at a position where the defect appears. In the defect inspection image generation step, when generating the defect inspection image, the color of the position where the amplitude value of the reflected ultrasonic beam is larger than the positive first threshold is white, and the reflected ultrasonic beam The color of the position where the amplitude value is smaller than the negative second threshold smaller than the first threshold is black,
In the defect inspection step, in the defect inspection image, a second white is next to the first black, the first white, and the second black in a direction from the inner surface to the outer surface of the welded steel pipe. The defect inspection method according to claim 12, wherein it is determined that the defect exists at a position where the defect appears. In the defect inspection image, the second direction indicates information related to a time when the reflected ultrasonic beam is received in the reception step,
In the defect inspection image, the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the first white appears and the position of the reflected ultrasonic beam among the positions where the second white appears. A time intermediate between the time corresponding to the position where the amplitude value is maximum is A, and B is the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is minimum among the positions where the second black appears. The defect inspection method according to claim 13, further comprising a defect size calculating step of calculating the size of the defect based on | A−B |. In the defect inspection image, the second direction indicates information related to a time when the reflected ultrasonic beam is received in the reception step,
In the defect inspection image, the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is minimum among the positions where the first black appears and the position of the reflected ultrasonic beam among the positions where the second black appears. A time intermediate between the time corresponding to the position where the amplitude value is minimum is A, and B is the time corresponding to the position where the amplitude value of the reflected ultrasonic beam is maximum among the positions where the second white appears. The defect inspection method according to claim 14, further comprising a defect size calculating step of calculating the size of the defect based on | A−B |.   17. The defect inspection image is generated by allocating an amplitude value of the reflected ultrasonic beam on a central locus of the ultrasonic beam in the defect inspection image generation step. The defect inspection method according to item.   The defect inspection method according to claim 10, further comprising a display step of displaying the defect inspection image on a display unit.   The program for making a computer perform each step in the defect inspection method of any one of Claims 10 thru | or 18.   A computer-readable storage medium storing the program according to claim 19.

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