Ultrasonic flaw detection apparatus

Abstract

To provide an ultrasonic flaw detector capable of improving an S / N ratio and increasing a frequency.SOLUTION: The ultrasonic flaw detection device includes a first number of ultrasonic units SU and an ultrasonic wave generation unit that causes each of the first number of ultrasonic units SU to generate an ultrasonic wave of a burst wave including a second number of temporally continuous waves, each of the first number of ultrasonic units SU includes a third number of ultrasonic probes, and the first number of ultrasonic units SU are arranged such that an interval between the ultrasonic units is a length based on a center wavelength of the ultrasonic wave of the burst wave. A third number of ultrasonic probes in one ultrasonic unit (SU) are arranged such that the interval between the ultrasonic probes is the center wavelength / the third number, when ultrasonic waves are generated, ultrasonic waves having phase differences are sequentially generated at 360 ° / the third number, and an ultrasonic wave generating section generates burst ultrasonic waves in the first number of ultrasonic units so as to be superimposed at the peak timing of at least one of the second number of waves.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic flaw detector that detects defects in an object using ultrasonic guided waves. [Background technology]

[0002] Ultrasonic flaw detectors that use ultrasonic waves to detect defects in a test object, such as cracks, cavities, inclusions, recesses, thinning, etc., are used in a variety of cases because they can inspect the test object nondestructively. One such ultrasonic flaw detector is one that uses guided waves, and is disclosed in, for example, Patent Document 1 and Patent Document 2.

[0003] An ultrasonic flaw detection device using guided waves, as disclosed in Patent Document 1, for example, is a device that propagates guided ultrasonic waves (guided ultrasonic waves) through an object to be detected and detects defects based on echo signals reflected by defects present along the propagation path. Guided ultrasonic waves inherently have a property called velocity dispersion, in which the propagation speed varies depending on the frequency. This velocity dispersion is a characteristic unique to guided ultrasonic waves that is not observed in general bulk ultrasonic waves that propagate through water or large metal blocks (see, for example, paragraphs

[0002] and

[0003] of Patent Document 1).

[0004] Furthermore, as disclosed in Patent Document 2, for example, the sound waves used in general sonic inspections have a high frequency of 5 MHz and a short wavelength of 0.6 mm, and are therefore easily attenuated. In contrast, the guided waves described above have a low frequency of 32 kHz and a long wavelength of 100 mm, and are therefore less likely to attenuate (for example, Patent Document 2).

[0005] paragraph). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-014345 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-149865 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in an ultrasonic flaw detector using a guided wave, as described above, the ultrasonic waves of the guided wave have velocity dispersion, which easily generates noise in the received ultrasonic signals (echo signals), making it difficult to detect signals due to relatively small defects. For this reason, there is a demand for improving the signal-to-noise ratio. Furthermore, in an ultrasonic flaw detector using a guided wave, as described above, the frequency of the ultrasonic waves of the guided wave is in the kHz band, so there is a demand for increasing the frequency of the ultrasonic waves of the guided wave, for example, to the MHz band, in order to detect relatively small defects. However, increasing the frequency makes the signal more susceptible to attenuation, which reduces the signals due to defects and makes them difficult to detect.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ultrasonic flaw detector that can further improve the S / N ratio and can operate at a higher frequency. [Means for solving the problem]

[0008] As a result of various studies, the inventors of the present invention have found that the above object can be achieved by the present invention described below. That is, an ultrasonic flaw detection device according to one aspect of the present invention comprises a first number of ultrasonic units arranged sequentially in one direction, and an ultrasonic generator that generates ultrasonic burst waves consisting of a second number of waves that are continuous in time in each of the first number of ultrasonic units, wherein the first number of ultrasonic units are arranged such that the interval between two adjacent ultrasonic units has a length based on the center wavelength of the ultrasonic burst waves, and the first number of ultrasonic units each comprise a third number of ultrasonic probes arranged sequentially in the one direction, and one ultrasonic generator generates ultrasonic burst waves consisting of a second number of waves that are continuous in time in each of the first number of ultrasonic units. The third number of ultrasonic probes in the ultrasonic unit are arranged such that the distance between two adjacent ultrasonic probes is a first division result obtained by dividing the center wavelength by the third number, and when generating ultrasonic waves, the third number of ultrasonic probes in one ultrasonic unit generate ultrasonic waves having sequential phase differences based on a second division result obtained by dividing 360° by the third number, and the ultrasonic wave generating unit generates the burst wave ultrasonic waves in each of the first number of ultrasonic units so that they are superimposed at the peak timing of at least one of the second number of waves.

[0009] In such an ultrasonic flaw detection device, the third ultrasonic probes in one ultrasonic unit generate ultrasonic waves having a phase difference sequentially as a result of the second division, and the first ultrasonic units each generate burst wave ultrasonic waves (guided wave ultrasonic waves) so that the waves are superimposed at the peak timing of at least one of the second number of waves.Therefore, compared to ultrasonic flaw detection using a single ultrasonic probe, the wavelength band of the guided wave ultrasonic waves can be narrowed and the amplitude at the peak timing of the superimposed waves can be increased, thereby further improving the signal-to-noise ratio and enabling higher frequencies.

[0010] In another aspect, in the ultrasonic flaw detection device described above, the first number of ultrasonic units are arranged such that the interval between two adjacent ultrasonic units is the same length as the center wavelength.

[0011] Such an ultrasonic flaw detection device is arranged so that the distance between two adjacent ultrasonic units is the same length as the center wavelength, so that burst ultrasonic waves can be generated with the phases aligned between the ultrasonic units, and therefore the ultrasonic waves of each ultrasonic unit can be superimposed at the peak timing of at least one of the second number of waves.

[0012] In another aspect, in the above-mentioned ultrasonic flaw detection device, the ultrasonic generating unit generates ultrasonic waves of a second number of burst waves, which is greater than the first number, from each of the first number of ultrasonic units to superimpose them at the peak timing of at least one of the second number of waves, and the third number is 2 or 4.

[0013] In such an ultrasonic flaw detection device, the second number of burst waves is greater than the first number of ultrasonic units, so that while the ultrasonic waves of the burst waves generated by the ultrasonic unit located at one end reach the ultrasonic unit located at the other end, the ultrasonic unit located at the other end generates ultrasonic waves of the burst waves, and therefore the ultrasonic waves of each ultrasonic unit can be superimposed at the peak timing of at least one of the second number of waves.

[0014] In another aspect, in the above-mentioned ultrasonic flaw detection device, the first number of ultrasonic units are arranged so that the distance between two adjacent ultrasonic units is an integer multiple of the center wavelength, and the ultrasonic generating unit generates ultrasonic waves from each of the first number of ultrasonic units with transmission timings that are sequentially shifted by the integer multiple of the wave period of the burst wave in order to superimpose them at the peak timing of at least one of the second number of waves.

[0015] In such an ultrasonic flaw detection device, the distance between two adjacent ultrasonic units and the transmission timing of each ultrasonic wave in the first number of ultrasonic units are set as described above, so there is no need to make the second number of waves in the burst wave greater than the first number of ultrasonic units.

[0016] In another aspect, in the above-mentioned ultrasonic flaw detection device, when the first number of ultrasonic units is an ultrasonic unit group, the device comprises a transmitting ultrasonic unit group, a receiving ultrasonic unit group, and a defect detection processing unit that transmits the burst wave ultrasonic waves to the test object using the transmitting ultrasonic unit group and detects defects in the test object based on the ultrasonic waves received by the receiving ultrasonic unit group, and the defect detection processing unit calculates the distance from the receiving ultrasonic unit group to the defect by multiplying the speed of sound of the ultrasonic waves by half the propagation time from the first reception point when the burst wave ultrasonic waves transmitted to the test object by the transmitting ultrasonic unit group are directly received by the receiving ultrasonic unit group to the second reception point when the ultrasonic waves reflected by the defect are received by the receiving ultrasonic unit group.

[0017] Such an ultrasonic flaw detector can determine the distance between a group of receiving ultrasonic units and a defect. [Effects of the Invention]

[0018] The ultrasonic flaw detector according to the present invention can further improve the signal-to-noise ratio and can operate at higher frequencies. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram showing the configuration of an ultrasonic flaw detection device according to an embodiment. [Figure 2] 3 is a diagram for explaining the configuration of a first embodiment of an ultrasonic unit group using a first embodiment of an ultrasonic unit in the ultrasonic flaw detection device. FIG. [Figure 3] 4 is a diagram for explaining the configuration of an ultrasonic unit of a second embodiment in the ultrasonic flaw detector. FIG. [Figure 4] 3A and 3B are diagrams for explaining ultrasonic burst waves used in the ultrasonic flaw detection device. [Figure 5] FIG. 10 is a diagram showing an example of an averaging result of a received signal. [Figure 6] FIG. 10 is a diagram showing a comparative example as an example. [Figure 7] 3 is a diagram for explaining a dispersion curve of stainless steel and a wavelength band of the ultrasonic flaw detector. FIG. [Figure 8] 4 is a flowchart showing an operation of the ultrasonic flaw detection device. [Figure 9] 10 is a diagram for explaining the configuration of a third embodiment of an ultrasonic unit group using the third embodiment of an ultrasonic unit in an ultrasonic flaw detector of a modified embodiment. FIG. [Figure 10] FIG. 10 is a diagram showing the case where m=1 as an example in the modified embodiment shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, components with the same reference numerals in each drawing indicate the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

[0021] FIG. 1 is a block diagram showing the configuration of an ultrasonic flaw detector according to an embodiment. FIG. 2 is a diagram illustrating the configuration of a first-type ultrasonic unit group using a first-type ultrasonic unit in the ultrasonic flaw detector. FIG. 3 is a diagram illustrating the configuration of a second-type ultrasonic unit in the ultrasonic flaw detector. FIG. 4 is a diagram illustrating burst wave ultrasonic waves used in the ultrasonic flaw detector. The horizontal axis of FIG. 4 represents time. FIG. 5 is a diagram illustrating, as an example, the arithmetic average result of received signals. The horizontal axis of FIG. 5 represents time, and the vertical axis represents the magnitude of the arithmetic average (arithmetic average value). FIG. 6 is a diagram illustrating, as an example, a comparative example. The horizontal axis of FIG. 6 represents time, and the vertical axis represents the magnitude of the received signal (signal value). FIG. 7 is a diagram illustrating the dispersion curve of stainless steel and the wavelength band of the ultrasonic flaw detector. The horizontal axis of FIG. 7 represents frequency [kHz], and the vertical axis represents the group velocity [m / s] of burst wave ultrasonic waves.

[0022] The ultrasonic flaw detection device 1000 in the embodiment includes, for example, an ultrasonic generating unit UG, a group of transmitting ultrasonic units TG, a group of receiving ultrasonic units RG, a control processing unit 1, and a memory unit 5, as shown in Figures 1 and 2, and in the example shown in Figures 1 and 2, further includes an input unit 2, a display unit 3, and an interface unit (IF unit) 4.

[0023] The transmitting ultrasonic unit group TG is a device that includes a first number h of ultrasonic units SU that are sequentially arranged in one direction and transmits ultrasonic waves of guided waves to the object WK. The receiving ultrasonic unit group RG is a device that includes a first number h of ultrasonic units SU that are sequentially arranged in one direction and receives ultrasonic waves that propagate through the object WK.

[0024] The first number h of ultrasonic units SU in the transmitting ultrasonic unit group TG each transmits ultrasonic burst waves consisting of a plurality of temporally continuous waves (a second number j) as guide waves to the subject WK for a relatively short predetermined time length. For example, ultrasonic burst waves BW consisting of five waves are shown in FIG. 4 (in this example, j=5). The second number j is arbitrary and is determined appropriately depending on, for example, the subject WK, specifications, etc.

[0025] The first number h of ultrasonic units SU in each of the transmitting ultrasonic unit group TG and the receiving ultrasonic unit group RG are arranged so that the interval between two adjacent ultrasonic units is a length based on the center wavelength λc of the ultrasonic burst waves. The ultrasonic burst waves have a frequency band within a predetermined frequency range depending on the frequencies of the waves constituting the burst waves and the second number j of the waves. The center wavelength λc is a wavelength corresponding to the center frequency fc of the frequency band of the ultrasonic burst waves. In the example shown in FIG. 2, for the sake of simplicity, the first number h is 3 (h=3), and the transmitting ultrasonic unit group TG includes three ultrasonic units, first to third, SU1 to SU3, which are arranged so that the interval between two adjacent ultrasonic units SU is the same length as the center wavelength λc. That is, the first and second ultrasonic units SU1 and SU2 are arranged at an interval of the center wavelength λc, and the second and third ultrasonic units SU2 and SU3 are arranged at an interval of the center wavelength λc. Similarly, the receiving ultrasonic unit group RG includes four to six ultrasonic units SU4 to SU6, which are arranged so that the interval between two adjacent ultrasonic units SU is the same length as the central wavelength λc. That is, the fourth and fifth ultrasonic units SU4, SU5 are arranged with an interval of the central wavelength λc between them, and the fifth and sixth ultrasonic units SU5, SU6 are arranged with an interval of the central wavelength λc between them.

[0026] The first number h of ultrasonic units SU in each of the transmitting ultrasonic unit group TG and the receiving ultrasonic unit group RG each includes a third number k of ultrasonic probes Pb arranged sequentially in one direction. Various types of ultrasonic probes are used for the ultrasonic probes Pb. For example, the ultrasonic probes Pb may be piezoelectric probes that transmit and receive ultrasonic waves using piezoelectric elements, or may be electromagnetic probes (EMATs, Electromagnetic Acoustic Transducers) that transmit and receive ultrasonic waves through electromagnetic action. EMATs are classified into Lorentz and magnetostrictive types, and EMATs do not require an acoustic coupling agent to transmit and receive ultrasonic waves and are capable of contactless measurement.

[0027] In each of the transmitting ultrasonic unit group TG and the receiving ultrasonic unit group RG, the third number k of ultrasonic probes Pb in one ultrasonic unit SU are arranged so that the interval between two adjacent ultrasonic probes Pb is the first division result λc / k obtained by dividing the center wavelength λc by the third number k, and when generating ultrasonic waves, ultrasonic waves having sequential phase differences are generated according to the second division result 360° / k obtained by dividing 360° by the third number k.

[0028] For example, an ultrasonic unit SU when the third number k is 2 is shown in FIG. 2 (k=2, ultrasonic unit SU of the first embodiment), and an ultrasonic unit SU when the third number k is 4 is shown in FIG. 3 (k=4, ultrasonic unit SU of the second embodiment).

[0029] As shown in FIG. 2, the ultrasonic unit SU (SU1, SU2, SU3; SU4, SU5, SU6) of this first embodiment includes two first and second ultrasonic probes Pb1 (Pb11, Pb21, Pb31; Pb41, Pb51, Pb61), Pb2 (Pb12, Pb22, Pb32; Pb42, Pb52, Pb62), and these first and second ultrasonic probes Pb1, Pb2 are arranged at an interval of the first division result λc / 2, and when generating ultrasonic waves, they generate ultrasonic waves having a phase difference of the second division result 360° / 2 (=180°). For example, ultrasonic unit SU1 includes first and second ultrasonic probes Pb11 and Pb12, which are spaced apart by the first division result λc / 2 and generate ultrasonic waves with a phase difference of 180°. That is, the ultrasonic waves generated by the second ultrasonic probe Pb12 have a phase difference of 180° with respect to the ultrasonic waves generated by the first ultrasonic probe Pb11. The other ultrasonic units SU2 and SU3 are similar to ultrasonic unit SU1. For example, ultrasonic unit SU4 includes first and second ultrasonic probes Pb41 and Pb42, which are spaced apart by the first division result λc / 2. The other ultrasonic units SU5 and SU6 are similar to ultrasonic unit SU4.

[0030] As shown in FIG. 3, the second embodiment of the ultrasonic unit SU7 includes four ultrasonic probes, first to fourth, Pb71, Pb72, Pb73, and Pb74, which are arranged at intervals of the first division result λc / 4, and when generating ultrasonic waves, each ultrasonic wave has a phase difference of the second division result 360° / 4 (=90°). That is, the ultrasonic unit SU7 comprises first to fourth ultrasonic probes Pb71 to Pb74, the first and second ultrasonic probes Pb71, Pb72 are arranged at an interval of the first division result λc / 4, and when generating ultrasonic waves, generate ultrasonic waves having a phase difference of 90°, the second and third ultrasonic probes Pb72, Pb73 are arranged at an interval of the first division result λc / 4, and when generating ultrasonic waves, generate ultrasonic waves having a phase difference of 90°, and the third and fourth ultrasonic probes Pb73, Pb74 are arranged at an interval of the first division result λc / 4, and when generating ultrasonic waves, generate ultrasonic waves having a phase difference of 90°. In other words, the ultrasonic waves generated by the second ultrasonic probe Pb72 have a phase difference of 90° with respect to the ultrasonic waves generated by the first ultrasonic probe Pb71, the ultrasonic waves generated by the third ultrasonic probe Pb73 have a phase difference of 90° with respect to the ultrasonic waves generated by the second ultrasonic probe Pb72 (the ultrasonic waves generated by the third ultrasonic probe Pb73 have a phase difference of 180° with respect to the ultrasonic waves generated by the first ultrasonic probe Pb71), and the ultrasonic waves generated by the fourth ultrasonic probe Pb74 have a phase difference of 90° with respect to the ultrasonic waves generated by the third ultrasonic probe Pb73 (the ultrasonic waves generated by the fourth ultrasonic probe Pb74 have a phase difference of 270° with respect to the ultrasonic waves generated by the first ultrasonic probe Pb71).

[0031] When the ultrasonic unit SU7 of this second aspect is used, the group of ultrasonic units TG for transmission includes, for example, three first to third ultrasonic units SU7 (SU71 to SU73, not shown), the first and second ultrasonic units SU71 and SU72 being spaced apart by the central wavelength λc, and the second and third ultrasonic units SU72 and SU73 being spaced apart by the central wavelength λc. Similarly, the group of ultrasonic units RG for reception includes three fourth to sixth ultrasonic units SU7 (SU74 to SU76, not shown), the fourth and fifth ultrasonic units SU74 and SU75 being spaced apart by the central wavelength λc, and the fifth and sixth ultrasonic units SU75 and SU76 being spaced apart by the central wavelength λc.

[0032] The distance between two adjacent ultrasonic units SU is defined as, for example, the length between an ultrasonic probe Pb at one end of one of the two ultrasonic units SU and an ultrasonic probe Pb at one end of the other of the two ultrasonic units SU.

[0033] The ultrasonic wave generating unit UG is connected to the control processing unit 1 and is a device that causes each of the first number h of ultrasonic units SU to generate ultrasonic waves of the burst wave according to the control of the control processing unit 1. As an example, in the case of an EMAT, the first number h of ultrasonic units SU in the transmitting ultrasonic unit group TG are connected in series, and the ultrasonic wave generating unit UG is connected to the input-side ultrasonic unit SU, and the ultrasonic wave generating unit UG generates ultrasonic waves of the burst wave in each of the first number h of ultrasonic units SU so that they overlap at the peak timing of at least one of the second number j of waves. In the example shown in FIG. 2, the input side of the first ultrasonic unit SU1 becomes the input side of the transmitting ultrasonic unit group TG, and the ultrasonic wave generating unit UG is connected to the input side of the first ultrasonic unit SU1. In the case of an EMAT, for example, the first ultrasonic unit SU1 is connected in series as described above, so the output side of the first ultrasonic unit SU1 is connected to the input side of the second ultrasonic unit SU2, the output side of the second ultrasonic unit SU2 is connected to the input side of the third ultrasonic unit SU3, and the output side of the third ultrasonic unit SU3 is connected to the ultrasonic generator UG (output part of the ultrasonic generator UG). The ultrasonic generator UG is configured to include, for example, a pulse oscillator that can oscillate the ultrasonic probe Pb at the frequency of the waves that make up the burst wave.

[0034] In this embodiment, the ultrasound generating unit UG generates a second number j of ultrasonic waves of burst waves, which is greater than the first number h, from each of the first number h of ultrasonic units SU (second number j>first number h) in order to superimpose them at the peak timing of at least one of the second number j of waves. In the transmitting ultrasound unit group TG configured as described above, if the second number j is less than the first number h (second number j<first number h), the ultrasound unit SU at the other end of the first number h of ultrasonic units SU sequentially arranged in one direction cannot superimpose the burst wave ultrasound on the burst wave ultrasound generated by the ultrasound unit SU at one end, because the burst wave ultrasound generated by the ultrasound unit SU at one end cannot propagate to the subject WK at the arrangement position of the ultrasound unit SU at the other end before the end timing at which the burst wave ultrasound generation is terminated. For this reason, the second number j needs to be greater than the first number h, and the transmitting ultrasonic unit group TG configured as described above can be superimposed by the ultrasonic generating unit UG at the peak timing of at least one of the waves of the second number j.

[0035] In the case of an EMAT as an example, the first number h of ultrasonic units SU in the receiving ultrasonic unit group RG are connected in series sequentially, and the control processing unit 1 is connected to the output ultrasonic unit SU, and the received ultrasonic signal is output to the control processing unit 1. In the example shown in FIG. 2, the output side of the sixth ultrasonic unit SU6 becomes the output side of the receiving ultrasonic unit group RG, and the control processing unit 1 is connected to the output side of the sixth ultrasonic unit SU6. Note that in the case of an EMAT as an example, since the series connection is as described above, the input side of the sixth ultrasonic unit SU6 is connected to the output side of the fifth ultrasonic unit SU5, the input side of the fifth ultrasonic unit SU5 is connected to the output side of the fourth ultrasonic unit SU4, and the input side of the fourth ultrasonic unit SU4 is connected to the control processing unit 1.

[0036] Therefore, the transmitting ultrasonic unit group TG and the receiving ultrasonic unit group RG have the same configuration, except that the transmitting ultrasonic unit group TG is connected to an ultrasonic generating unit UG, and the receiving ultrasonic unit group RG is connected to a control processing unit 1.

[0037] 1 and 2, the first number h is three, but the first number h is not limited to three and may be any number. The second number j may be any number as long as it is greater than the first number h (second number j > first number h). The third number k is two in the examples shown in FIGS. 1 and 2 and four in the example shown in FIG. 3, but the third number k is not limited to these and may be any number. The center frequency fc is preferably set in the MHz band in order to detect relatively small defects.

[0038] The input unit 2 is connected to the control processing unit 1 and is a device that inputs various commands, such as a command to start flaw detection, and various data required to operate the ultrasonic flaw detection device 1000, such as the name of the test object, to the ultrasonic flaw detection device 1000, and is, for example, a keyboard, a mouse, and a plurality of input switches to which predetermined functions are assigned. The display unit 3 is connected to the control processing unit 1 and is a device that displays the commands and data input from the input unit 2 and the results of ultrasonic flaw detection under the control of the control processing unit 1, and is, for example, a display device such as a CRT display, an LCD (liquid crystal display), or an organic EL display.

[0039] The input unit 2 and the display unit 3 may be configured with a touch panel. In the case where the input unit 2 is configured with this touch panel, the input unit 2 is, for example, a resistive or capacitive position input device that detects and inputs an operation position. In this touch panel, a position input device is provided on the display surface of the display unit 3, and one or more input content candidates that can be input are displayed on the display unit 3. When a user touches the display position displaying the input content they want to input, the position is detected by the position input device, and the display content displayed at the detected position is input to the ultrasonic flaw detection device 1000 as the user's operation input content. With such a touch panel, the user can easily intuitively understand the input operation, and therefore, an ultrasonic flaw detection device 1000 that is easy for the user to use is provided.

[0040] The IF unit 4 is connected to the control processing unit 1 and is a circuit that inputs and outputs data to and from, for example, an external device under the control of the control processing unit 1, and is, for example, an interface circuit for RS-232C, which is a serial communication method, an interface circuit using the Bluetooth (registered trademark) standard, an interface circuit using the USB standard, etc. The IF unit 4 may also be, for example, a communication interface circuit that transmits and receives communication signals to and from an external device, such as a data communication card or a communication interface circuit conforming to the IEEE802.11 standard, etc.

[0041] The storage unit 5 is connected to the control processing unit 1 and is a circuit that stores various predetermined programs and various predetermined data under the control of the control processing unit 1.

[0042] The various predetermined programs include, for example, a control processing program, and the control processing program includes, for example, a control program and a defect detection processing program, etc. The control program is a program that controls each of the parts UG, TG, RG, 2 to 5 of the ultrasonic flaw detection device 1000 according to the function of each part. The defect detection processing program is a program that transmits the ultrasonic burst waves to the test object WK using the ultrasonic transmitting unit group TG, and detects defects in the test object WK based on the ultrasonic waves received by the ultrasonic receiving unit group RG.

[0043] The various predetermined data include data necessary for executing each of these programs, such as the object name, the second number j, the ultrasonic reception signal, the sound speed Vs at the center wavelength λc, a threshold (direct determination threshold) Thd for detecting direct ultrasonic waves received directly by the receiving ultrasonic unit group RG from the transmitting ultrasonic unit group TG, and a threshold (defect determination threshold) The for detecting ultrasonic waves (echoes) from defects. Since the intensity of the direct ultrasonic waves is relatively large compared to the intensity of ultrasonic waves from defects, the direct determination threshold Thd is set to a relatively large value compared to the defect determination threshold The (Thd>>The).

[0044] The storage unit 5 includes, for example, a ROM (Read Only Memory), which is a nonvolatile storage element, and an EEPROM (Electrically Erasable Programmable Read Only Memory), which is a rewritable nonvolatile storage element. The storage unit 5 also includes a RAM (Random Access Memory), which serves as a working memory for the control processing unit 1 and stores data generated during execution of the predetermined program. The storage unit 5 may also be configured with a hard disk drive or solid state drive (SSD) with a relatively large storage capacity.

[0045] The control processing unit 1 is a circuit for controlling each of the units UG, TG, RG, 2 to 5 of the ultrasonic flaw detection device 1000 in accordance with the function of each unit, and for performing ultrasonic flaw detection. The control processing unit 1 is configured to include, for example, a CPU (Central Processing Unit) and its peripheral circuits. In the control processing unit 1, a control unit 11 and a defect detection processing unit 12 are functionally configured by executing the control processing program.

[0046] The control unit 11 controls each of the units UG, TG, RG, 2 to 5 of the ultrasonic flaw detector 1000 in accordance with the function of each unit, and is in charge of overall control of the ultrasonic flaw detector 1000.

[0047] The defect detection processing unit 12 transmits the ultrasonic burst waves to the inspection object WK using the ultrasonic transmitting unit group TG, and detects defects in the inspection object WK based on the ultrasonic waves received by the ultrasonic receiving unit group RG. The defect detection processing unit 12 calculates the distance L (=(Δt / 2)×Vs) from the ultrasonic receiving unit group RG to the defect by multiplying the ultrasonic wave speed Vs by Δt / 2, which is half the propagation time Δt (=tr2-tr1) from the first reception time tr1 at which the ultrasonic burst waves transmitted to the inspection object WK by the ultrasonic transmitting unit group TG are received directly (without passing through a defect) by the ultrasonic receiving unit group RG, to the second reception time tr2 at which the ultrasonic waves reflected by the defect are received by the ultrasonic receiving unit group RG. The distance L to the defect is defined, for example, as the length from the center position of the ultrasonic receiving unit group RG to the defect.

[0048] More specifically, the defect detection processing unit 12 detects signals equal to or greater than the direct judgment threshold Thd as direct ultrasonic signals from the ultrasonic reception signals received by the ultrasonic receiving unit group RG, thereby detecting a first reception time point tr1. Then, the defect detection processing unit 12 detects signals equal to or greater than the defect judgment threshold The from the ultrasonic reception signals received by the ultrasonic receiving unit group RG as ultrasonic signals (echo signals) reflected from defects, detects peaks from the detected signals equal to or greater than the defect judgment threshold The, determines the time of the detected peak as a second reception time point tr2, and calculates the distance L to the defect. The defect judgment threshold The is appropriately set in advance from, for example, multiple samples. When multiple signals equal to or greater than the defect judgment threshold The are detected, the peaks and distances L are calculated for each of the detected signals equal to or greater than the defect judgment threshold The as ultrasonic signals reflected from each of the multiple defects, thereby detecting multiple defects.

[0049] An example of a reception signal of ultrasonic waves received by the receiving ultrasonic unit group RG is shown in Fig. 5. Fig. 6 shows a reception signal of ultrasonic waves in a comparative example.

[0050] The test object WK is a stainless steel object with a diameter of 7 mm and a small flat-bottom hole with a diameter of 0.5 mm and a depth of 0.6 mm formed on its surface. There are nine ultrasonic units SU in the transmitting ultrasonic unit group TG and the receiving ultrasonic unit group RG (h=9), and as in the example shown in Figure 2, each is configured with two first and second ultrasonic probes Pb1 and Pb2 (k=2). There are 11 waves that make up the burst wave (j=11), the center frequency fc is 1.5 MHz (center wavelength λc=approximately 1.9 mm), and the sound speed Vs is approximately 2800 m / s.

[0051] In the example shown in Figure 5, ultrasonic waves were transmitted and received 64 times, resulting in 64 received signals. These received signals, each with the same transmission timing, were added together and averaged to obtain an averaging result. That is, for each of the 64 received signals with the same transmission timing, the values ​​at the same timing on the time axis were added together and simply averaged to obtain the averaging result. Figure 5 shows this averaging result.

[0052] In the comparative example, one ultrasonic probe Pb transmits ultrasonic waves to the object WK, and one ultrasonic probe Pb receives ultrasonic waves from the object WK, and the received ultrasonic signals are shown in FIG.

[0053] In the comparative example, in the case of burst wave ultrasonic waves, various modes of ultrasonic waves (dispersion curves for six modes are shown in FIG. 7) are generated in the test object WK due to velocity dispersion, and due to the superposition of ultrasonic waves of each mode, only a noisy signal mW is obtained as shown in FIG. 6, and the minute defect cannot be detected. When an attempt is made to detect a defect, two defects are detected because the signal mW has two relatively large peaks, resulting in a false detection.

[0054] In contrast, in the ultrasonic flaw detection device 1000 of this embodiment, as shown in FIG. 5, noise due to the superposition of ultrasonic waves of each mode in the ultrasonic burst wave is reduced, and the S / N ratio is improved compared to the comparative example shown in FIG. 6. Therefore, in the ultrasonic flaw detection device 1000 of this embodiment, the peak pW of the signal due to the defect is easily detected. Note that the signal DRW immediately after the start of transmission is a signal received directly from the transmitting ultrasonic unit group TG by the receiving ultrasonic unit group RG (a received signal of a direct ultrasonic wave (direct wave)). In FIG. 5, the time difference from the direct ultrasonic wave to the peak pW is approximately 145 μs, and the distance L from the receiving ultrasonic unit group RG to the defect (a tiny flat-bottom hole) is approximately 200 mm.

[0055] In Figure 5, the arithmetic average result is calculated, but the multiplication average result may also be calculated by multiplying each value at the same timing on the time axis and calculating a simple average for each of the 64 received signals, with the transmission timing of each received signal being aligned.

[0056] The control processing unit 1, input unit 2, display unit 3, IF unit 4 and storage unit 5 in such an ultrasonic flaw detector 1000 can be configured by, for example, a desktop or notebook computer.

[0057] Next, the operation of this embodiment will be described with reference to a flowchart shown in FIG.

[0058] When the ultrasonic flaw detection device 1000 having such a configuration is powered on, it initializes the necessary parts and starts its operation. The control processing unit 1 executes a control processing program to functionally configure a control unit 11 and a defect detection processing unit 12. A transmitting ultrasonic unit group TG and a receiving ultrasonic unit group RG are set in the test object WK.

[0059] In FIG. 8, first, the ultrasonic flaw detection device 1000 causes the defect detection processing unit 12 of the control processing unit 1 to cause the transmitting ultrasonic unit group TG to transmit burst wave ultrasonic waves to the test object WK via the ultrasonic generator UG (S1), and then receives ultrasonic waves from the test object WK with the receiving ultrasonic unit group RG (S2).

[0060] Next, the ultrasonic flaw detection device 1000 detects the first and second reception times tr1 and tr2 based on the received signals of the ultrasonic waves received by the receiving ultrasonic unit group RG using the defect detection processing unit 12, and calculates the distance L from the receiving ultrasonic unit group RG to the defect (S3).

[0061] Then, the ultrasonic flaw detection device 1000 causes the defect detection processing unit 12 to display the distance L to the flaw calculated in step S3 on the display unit 3 (S4), and ends this processing. Note that the display unit 3 may display, for example, the ultrasonic reception signal shown in Fig. 5, and the defect detection processing unit 12 may output the flaw detection results (distance L, ultrasonic reception signal) to an external device via the IF unit 4 as necessary.

[0062] As explained above, in the ultrasonic flaw detection apparatus 1000 of the embodiment, the third number k of ultrasonic probes Pb in one ultrasonic unit SU generate ultrasonic waves having sequential phase differences as a result of the second division, and the first number h of ultrasonic units SU generate ultrasonic burst waves (ultrasonic guided waves) so that they are superimposed at the peak timing of at least one of the second number j of waves. Therefore, compared to ultrasonic flaw detection using a single ultrasonic probe, the wavelength band of the guided wave ultrasonic waves can be narrowed and the amplitude at the peak timing of the superimposed waves can be increased, thereby further improving the signal-to-noise ratio and enabling higher frequencies. The ultrasonic flaw detection apparatus 1000 can operate at higher frequencies, thereby improving the spatial resolution of ultrasonic flaw detection and enabling the detection of relatively small defects.

[0063] The ultrasonic flaw detection device 1000 is arranged so that the distance between two adjacent ultrasonic units SU is the same length as the center wavelength λc, so that ultrasonic burst waves can be generated with the phases aligned between the ultrasonic units SU, and therefore the ultrasonic waves of each ultrasonic unit can be superimposed at the peak timing of at least one of the second number of waves.

[0064] In the ultrasonic flaw detection device 1000, the second number j of burst wave waves is greater than the first number h of ultrasonic units SU, so that while the ultrasonic burst wave waves generated by the ultrasonic unit SU located at one end reach the ultrasonic unit SU located at the other end, the ultrasonic burst wave waves are generated by the ultrasonic unit SU located at the other end, and therefore the ultrasonic waves of each ultrasonic unit SU can be superimposed at the peak timing of at least one of the second number j of waves.

[0065] The ultrasonic flaw detector 1000 can obtain the distance between the group of ultrasonic receiving units and the defect.

[0066] Fig. 9 is a diagram for explaining the configuration of a third embodiment of an ultrasonic unit group using a third embodiment of an ultrasonic unit in an ultrasonic flaw detection device of a modified embodiment. Fig. 10 is a diagram showing, as an example, a case where m=1 in the modified embodiment shown in Fig. 9. Fig. 9A and Fig. 10A show the configuration of the third embodiment of an ultrasonic unit and the third embodiment of an ultrasonic unit group, and Fig. 9B and Fig. 10B show the transmission timing of each ultrasonic unit.

[0067] In the above-described embodiment, as shown in FIG. 9A, the first number h of ultrasonic units SUa are arranged so that the interval between two adjacent ultrasonic units SU is a length mλc that is an integer multiple m of the center wavelength λc, and as shown in FIG. 9B, the ultrasonic generating unit UG may cause each of the first number h of ultrasonic units SU to generate ultrasonic waves with transmission timings (generation timings) that are sequentially shifted by the integer multiple m of the wave period of the burst wave in order to superimpose them at the peak timing of at least one of the second number j of waves.

[0068] 9A, the transmitting ultrasonic unit group TGa includes three first to third ultrasonic units SU11, SU12, and SU13 that are sequentially arranged in one direction. The first and second ultrasonic units SU11 and SU12 are arranged at an interval mλc that is an integer multiple m of the center wavelength λc, and the second and third ultrasonic units SU12 and SU13 are arranged at an interval mλc that is an integer multiple m of the center wavelength λc. Similarly, the receiving ultrasonic unit group RGa (not shown) includes three fourth to sixth ultrasonic units SU14 to SU16 (not shown), and are arranged so that the interval between two adjacent ultrasonic units SU is mλc that is an integer multiple m of the center wavelength λc. That is, the fourth and fifth ultrasonic units SU14 and SU15 are arranged at an interval mλc, which is an integer multiple m of the central wavelength λc, and the fifth and sixth ultrasonic units SU15 and SU16 are arranged at an interval mλc, which is an integer multiple m of the central wavelength λc.

[0069] If the wave period of the burst wave is T, as shown in FIG. 9B, the ultrasonic wave generating unit UG causes the second ultrasonic unit SU12 to transmit ultrasonic waves at transmission timing t12 that is delayed by mT from the transmission timing t11 at which the first ultrasonic unit SU11 transmitted ultrasonic waves, and causes the third ultrasonic unit SU13 to transmit ultrasonic waves at transmission timing t13 that is delayed by mT from the transmission timing t12 at which the second ultrasonic unit SU12 transmitted ultrasonic waves.

[0070] 10 specifically shows a case where m = 1. In this case, the transmitting ultrasonic unit group TGb includes three ultrasonic units, first to third ultrasonic units SU1, SU2, and SU3, arranged sequentially in one direction, as shown in FIG. 10A. The first and second ultrasonic units SU1 and SU2 are arranged at an interval λc that is one time the center wavelength λc, and the second and third ultrasonic units SU2 and SU3 are arranged at an interval λc that is one time the center wavelength λc. The same applies to the receiving ultrasonic unit group. Then, as shown in FIG. 10B, the ultrasonic generator UG causes the second ultrasonic unit SU2 to transmit ultrasonic waves at transmission timing t2, which is delayed by T from the transmission timing t1 at which the first ultrasonic unit SU1 transmitted ultrasonic waves, and causes the third ultrasonic unit SU3 to transmit ultrasonic waves at transmission timing t3, which is delayed by T from the transmission timing t2 at which the second ultrasonic unit SU2 transmitted ultrasonic waves.

[0071] In the examples shown in FIGS. 9 and 10, one ultrasonic unit SU includes two ultrasonic probes Pb, but the third number k of the ultrasonic probes Pb may be any number.

[0072] In the ultrasonic flaw detection device 1000 using such third and fourth types of ultrasonic unit groups for transmission and reception, the spacing between two adjacent ultrasonic units SU and the transmission timing of each ultrasonic wave in the first number h of ultrasonic units SU are set as described above, so there is no need to make the second number j of waves in the burst wave greater than the first number h of ultrasonic units SU.

[0073] In order to express the present invention, the present invention has been properly and sufficiently described above through the embodiments with reference to the drawings, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0074] 1000 Ultrasonic flaw detection equipment Ultrasonic unit group for transmitting TG, TGa, and TGb RG receiving ultrasonic units SU (SU1 to SU6, SU7, SU11 to SU13) ultrasonic unit Pb (Pb11~Pb61, Pb12~Pb62, Pb71~Pb74) Ultrasonic probe BW Burst wave ultrasound 1 Control processing section 2 Input section 3 Display section 4 Interface section (IF section) 5 Storage section 11 Control section 12 Defect detection processing section

Claims

1. a first number of ultrasonic units arranged sequentially in one direction; an ultrasonic wave generating unit that generates ultrasonic waves of burst waves consisting of a plurality of time-sequential waves of a second number in each of the first number of ultrasonic wave units, The first number of ultrasonic units are arranged such that the interval between two adjacent ultrasonic units is a length based on the center wavelength of the ultrasonic waves of the burst wave, each of the first number of ultrasound units includes a third number of ultrasound probes sequentially arranged in the one direction; the third number of ultrasonic probes in one ultrasonic unit are arranged such that the interval between two adjacent ultrasonic probes is a first division result obtained by dividing the center wavelength by the third number, When generating ultrasonic waves, the third number of ultrasonic probes in one ultrasonic unit each generate ultrasonic waves having a phase difference sequentially according to a second division result obtained by dividing 360° by the third number, The ultrasonic wave generating unit generates ultrasonic waves of the burst waves from each of the first number of ultrasonic wave units so that the waves are superimposed at peak timings of at least any of the second number of waves. Ultrasonic flaw detection equipment.

2. The first number of ultrasonic units are arranged such that the interval between two adjacent ultrasonic units is the same length as the center wavelength. The ultrasonic flaw detection device according to claim 1.

3. The ultrasonic wave generating unit generates ultrasonic waves of a second number of burst waves, which is greater than the first number, from each of the first number of ultrasonic wave units in order to superimpose the waves at peak timings of at least any of the second number of waves, the third number is 2 or 4; The ultrasonic flaw detector according to claim 2.

4. The first number of ultrasonic units are arranged such that the interval between two adjacent ultrasonic units is an integer multiple of the center wavelength, The ultrasonic wave generating unit generates ultrasonic waves from each of the first number of ultrasonic units, the ultrasonic waves having transmission timings sequentially shifted by the integral multiple of the wave period of the burst wave, in order to superimpose the waves at peak timings of at least one of the second number of waves. The ultrasonic flaw detection device according to claim 1.

5. When the first number of ultrasonic units are defined as an ultrasonic unit group, a group of ultrasonic units for transmission and a group of ultrasonic units for reception are defined as follows: a defect detection processing unit that transmits ultrasonic burst waves to an object to be inspected by the group of ultrasonic transmitting units and detects defects in the object to be inspected based on the ultrasonic waves received by the group of ultrasonic receiving units, The defect detection processing unit calculates the distance from the group of ultrasonic receiving units to the defect by multiplying half the propagation time from a first reception time point when the ultrasonic burst waves transmitted to the test object by the group of ultrasonic receiving units are directly received by the group of ultrasonic receiving units to a second reception time point when the ultrasonic waves reflected by the defect are received by the group of ultrasonic receiving units. The ultrasonic flaw detection device according to claim 1.

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