JP7463202B2 - Ultrasonic inspection device and ultrasonic inspection method - Google Patents

Description

The present invention relates to an ultrasonic inspection device and an ultrasonic inspection method.

A method of inspecting defective parts of an object to be inspected using an ultrasonic beam is known. For example, if there is a defective part (cavity, etc.) with a small acoustic impedance such as air inside the object to be inspected, a gap in acoustic impedance will occur inside the object to be inspected, and the amount of transmission of the ultrasonic beam will be small. Therefore, by measuring the amount of transmission of the ultrasonic beam, it is possible to detect defective parts inside the object to be inspected.

The technology described in Patent Document 1 is known for an ultrasonic inspection device. In the ultrasonic inspection device described in Patent Document 1, a rectangular wave burst signal consisting of a predetermined number of consecutive negative rectangular waves is applied to a transmitting ultrasonic probe arranged opposite the object to be inspected through the air. The ultrasonic waves propagated through the object are converted into a transmitted wave signal by a receiving ultrasonic probe arranged opposite the object to be inspected through the air. The presence or absence of a defect in the object is determined based on the signal level of this transmitted wave signal. In addition, the transmitting ultrasonic probe and the receiving ultrasonic probe have a lower acoustic impedance of the transducer and the front panel attached to the ultrasonic transmission and reception side of the transducer compared to a contact type ultrasonic probe that is used by abutting against the object.

JP 2008-128965 A (particularly the Abstract)

In the ultrasonic inspection device described in Patent Document 1, when a defect is smaller than the size (beam diameter) of the ultrasonic beam, a large amount of the ultrasonic beam passes through the periphery of the defect, making it difficult to detect a signal change resulting from the defect. For this reason, there is room for improvement in the performance of detecting defects.
The problem to be solved by the present invention is to provide an ultrasonic inspection device and an ultrasonic inspection method that are excellent in the performance of detecting defects, in particular in the detection sensitivity.

The ultrasonic inspection device of the present invention is an ultrasonic inspection device that inspects an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, and includes a scanning measurement device that scans and measures the ultrasonic beam on the object to be inspected, and a control device that controls the driving of the scanning measurement device, the scanning measurement device includes a transmitting probe that emits the ultrasonic beam, and an eccentrically arranged receiving probe that is installed on the opposite side of the transmitting probe with respect to the object to be inspected and receives the ultrasonic beam, the eccentrically arranged receiving probe is arranged so that the eccentric distance between the transmitting sound axis of the transmitting probe and the receiving sound axis of the eccentrically arranged receiving probe is larger than zero , and the focal length of the eccentrically arranged receiving probe is longer than the focal length of the transmitting probe . Other solutions will be described later in the description of the embodiment of the invention.

The present invention provides an ultrasonic inspection device and an ultrasonic inspection method that have excellent defect detection performance, particularly excellent detection sensitivity.

1 is a diagram showing the configuration of an ultrasonic inspection apparatus according to a first embodiment; FIG. 2 is a diagram for explaining the transmission sound axis, the reception sound axis, and the eccentricity distance, in the case where the transmission sound axis and the reception sound axis extend in the vertical direction. 1 is a diagram for explaining a transmission sound axis, a reception sound axis, and an eccentric distance, in which the transmission sound axis and the reception sound axis extend at an angle. FIG. FIG. 2 is a functional block diagram of a control device. 3 is a schematic cross-sectional view showing a structure of a transmission probe. FIG. 13 is a diagram showing a received waveform from an eccentrically placed receiving probe, the received waveform being obtained at a healthy portion N of an object E to be inspected. FIG. 13 is a diagram showing a received waveform from an eccentrically disposed receiving probe, the received waveform being detected at a defective portion D of an object E to be inspected. FIG. FIG. 1 shows an example plot of signal strength data. 4 is a diagram showing a propagation path of an ultrasonic beam in the present embodiment, in which the ultrasonic beam is incident on a healthy part. FIG. 4 is a diagram showing a propagation path of an ultrasonic beam in this embodiment, illustrating a case where the ultrasonic beam is incident on a defect portion. FIG. FIG. 1 is a diagram showing a propagation path of an ultrasonic beam in a conventional ultrasonic inspection method, showing the time when the ultrasonic beam is incident on a healthy part. FIG. 1 is a diagram showing a propagation path of an ultrasonic beam in a conventional ultrasonic inspection method, showing the time of incidence on a defect portion. FIG. 1 shows a plot of signal intensity data for a conventional ultrasound inspection method. FIG. 2 is a diagram showing an interaction between an ultrasonic beam and a defect in an object to be inspected, showing how a direct ultrasonic beam is received. FIG. 2 is a diagram showing an interaction between a defect in an object to be inspected and an ultrasonic beam, showing how scattered waves are received. 3 is a flowchart showing an ultrasonic inspection method according to the first embodiment. FIG. 2 is a diagram illustrating a hardware configuration of a control device. 13 is a diagram showing the relationship between a transmitting probe and an eccentrically disposed receiving probe in an ultrasonic inspection device according to a second embodiment. FIG. 11A and 11B are diagrams illustrating the relationship between the beam incidence area in a transmitting probe and the beam incidence area in an eccentrically disposed receiving probe. FIG. 13 is a diagram showing an example of an eccentrically arranged receiving probe according to the third embodiment. FIG. 13 is a diagram showing the configuration of a scanning measurement device of an ultrasonic inspection apparatus according to a fourth embodiment. 13A to 13C are diagrams for explaining the reason why the fourth embodiment has an effect. FIG. 13 is a diagram showing the configuration of an ultrasonic inspection apparatus according to a fifth embodiment. FIG. 13 is a functional block diagram of an ultrasonic inspection apparatus according to a fifth embodiment. FIG. 13 is a diagram showing the arrangement of an eccentrically arranged receiving probe in the sixth embodiment. FIG. 23 is a diagram showing the arrangement of eccentrically arranged receiving probes in the seventh embodiment, in which the unit probes are arranged at an angle. FIG. 23 is a diagram showing the arrangement of eccentrically arranged receiving probes in the seventh embodiment, in which the unit probes are arranged in the vertical direction. FIG. 23 is a diagram showing the configuration of an ultrasonic inspection apparatus according to an eighth embodiment. FIG. 23 is a functional block diagram of an ultrasonic inspection device according to an eighth embodiment. FIG. 13 is a diagram showing the configuration of a defect information determination unit of an ultrasonic inspection apparatus according to a ninth embodiment. 11 is a diagram showing changes at a measurement point in a signal received by a coaxially arranged receiving probe. FIG. 11 is a diagram showing changes at a measurement point in a signal received by an eccentrically disposed receiving probe. FIG. 11 is a diagram showing changes at a measurement point of an interference signal synthesized by an interference signal generating unit 231. FIG. FIG. 23 is a diagram showing the configuration of an ultrasonic inspection apparatus according to a tenth embodiment. FIG. 23 is a diagram showing the configuration of an ultrasonic inspection apparatus according to an eleventh embodiment. FIG. 23 is a diagram showing the configuration of an ultrasonic inspection apparatus according to a twelfth embodiment.

Below, a form for carrying out the present invention (referred to as an embodiment) will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and for example, different embodiments can be combined, or modified as desired without significantly impairing the effects of the present invention. In addition, the same symbols will be used for the same components, and duplicate descriptions will be omitted. Furthermore, parts having the same functions will be given the same names. The contents shown are merely schematic, and for convenience of illustration, the actual configuration may be changed without significantly impairing the effects of the present invention.

Figure 1 is a diagram showing the configuration of an ultrasonic inspection device Z of the first embodiment. In Figure 1, the scanning measurement device 1 is shown in a schematic cross-sectional view. Also shown is a coordinate system of three orthogonal axes, including the x-axis as a direction perpendicular to the paper surface, the y-axis as a direction to the left and right of the paper surface, and the z-axis as a direction to the top and bottom of the paper surface.

The ultrasonic inspection device Z inspects the object E by irradiating an ultrasonic beam U (Figure 4) onto the object E through a gas. The gas is, for example, air, and the inside of the housing 101 of the scanning measurement device 1 is hollow. As shown in Figure 1, the ultrasonic inspection device Z includes the scanning measurement device 1, a control device 2, and a display device 3. The display device 3 is connected to the control device 2.

The scanning measurement device 1 scans and measures an ultrasonic beam U on an object to be inspected E, and includes a sample stage 102 fixed to a housing 101, on which the object to be inspected E is placed. The object to be inspected E may be any material that has a faster sound speed than a gas such as air. The object to be inspected E is, for example, a solid material, and more specifically, may be, for example, a metal, glass, a resin material, or a composite material such as CFRP (Carbon-Fiber Reinforced Plastics). In the example of FIG. 1, the object to be inspected E has a defective portion D inside. The defective portion D is a cavity or the like. In the object to be inspected E, the portion other than the defective portion D is referred to as a healthy portion N.

The scanning measurement device 1 includes a probe P (see FIG. 4 ) and a transmitting probe 110 that emits an ultrasonic beam U, and an eccentrically arranged receiving probe 120. The transmitting probe 110 is installed in the housing 101 via a transmitting probe scanning unit 103, and emits an ultrasonic beam U. The eccentrically arranged receiving probe 120 is a receiving probe 121 that is installed on the opposite side of the transmitting probe 110 with respect to the object E to receive the ultrasonic beam U. The eccentrically arranged receiving probe 120 has a receiving sound axis AX2 at a position different from the transmitting sound axis AX1 of the transmitting probe 110. The distance between the transmitting sound axis AX1 and the receiving sound axis AX2 is the eccentric distance L. The eccentrically arranged receiving probe 120 is installed in the housing 101 via a receiving probe scanning unit 104.
In this specification, among the receiving probes 121 that receive ultrasonic waves, those arranged at a position where the eccentricity distance L is equal to or greater than zero are defined as eccentrically arranged receiving probes 120, and those arranged at a position where the eccentricity distance L is zero are defined as coaxially arranged receiving probes 140. In other words, the receiving probe 121 is a term that encompasses the eccentrically arranged receiving probes 120 and the coaxially arranged receiving probes 140.

Here, "the opposite side of the transmitting probe 110" means, of the two spaces separated by the subject E, the space opposite the space in which the transmitting probe 110 is located (opposite side in the z-axis direction), and does not mean the opposite side with the same x and y coordinates (i.e., a position symmetrical with respect to the xy plane). As shown in FIG. 1, the transmitting probe 110 and the eccentrically placed receiving probe 120 are installed so that the transmitting sound axis AX1 and the receiving sound axis AX2 are offset by the eccentricity distance L. The specific details of the transmitting sound axis AX1, the receiving sound axis AX2, and the eccentricity distance L will be described later.

As the receiving probe scanning unit 104 moves, the eccentrically placed receiving probe 120 scans the sample stage 102 in the x-axis and y-axis directions. The transmitting probe 110 and the eccentrically placed receiving probe 120 scan the object under test E in the x-axis or y-axis directions while maintaining the eccentricity distance L between them (thick double arrow).

In the scanning measurement device 1, the eccentric distance L is set as follows, although details of both will be described later. That is, the eccentric distance L is set to a distance that allows reception of scattered waves U1 generated by scattering of the ultrasonic beam U at the defective portion D of the object E to be inspected. Alternatively, the eccentric distance L is set so that the received signal strength at the eccentrically placed receiving probe 120 when incident on the defective portion D of the object E to be inspected is greater than the received signal strength when incident on a healthy portion N of the object E to be inspected. Alternatively, the eccentric distance L is set to a distance at which no received signals other than noise are detected when irradiating the healthy portion N of the object E to be inspected.

The scanning measurement device 1 includes an eccentric distance adjustment unit 105 that adjusts the position of at least one of the transmitting probe 110 or the eccentrically arranged receiving probe 120 so that the eccentric distance L between the transmitting sound axis AX1 and the receiving sound axis AX2 is greater than zero. The eccentric distance adjustment unit 105 (eccentric distance adjustment mechanism) is provided in the receiving probe scanning unit 104 installed in the housing 101. The eccentric distance adjustment unit 105 is provided with the eccentrically arranged receiving probe 120. The eccentric distance adjustment unit 105 can move the eccentrically arranged receiving probe 120 independently of the position of the receiving probe scanning unit 104, and can set the deviation between the receiving sound axis AX2 and the transmitting sound axis AX1 to be the eccentric distance L. The eccentric distance adjustment unit 105 may be provided on the transmitting probe scanning unit 103 side. In other words, as long as the deviation between the receiving sound axis AX2 and the transmitting sound axis AX1 can be set to the eccentricity distance L, the eccentricity distance adjustment unit 105 may be provided on the receiving probe 121 side or on the transmitting probe 110 side.

The control device 2 is connected to the scanning measurement device 1. The control device 2 controls the driving of the scanning measurement device 1, and controls the movement (scanning) of the transmitting probe 110 and the eccentrically arranged receiving probe 120 by instructing the transmitting probe scanning unit 103 and the receiving probe scanning unit 104. The transmitting probe scanning unit 103 and the receiving probe scanning unit 104 move synchronously in the x-axis and y-axis directions, so that the transmitting probe 110 and the eccentrically arranged receiving probe 120 scan the subject E in the x-axis and y-axis directions. Furthermore, the control device 2 emits an ultrasonic beam U from the transmitting probe 110, and performs waveform analysis based on the signal acquired from the eccentrically arranged receiving probe 120.

In this embodiment, an example is shown in which the transmitting probe 110 and the eccentrically arranged receiving probe 120 are scanned in a state in which the object to be inspected E is fixed to the housing 101 via the sample stage 102, that is, in a state in which the object to be inspected E is fixed to the housing 101. Conversely, a configuration in which the transmitting probe 110 and the eccentrically arranged receiving probe 120 are fixed to the housing 101 and scanning is performed by moving the object to be inspected E may also be used.

A gas phase is present between the transmitting probe 110 and the subject E, and between the eccentrically placed receiving probe 120 and the subject E. In other words, the ultrasonic inspection device Z is a non-contact type ultrasonic inspection device Z in which neither the transmitting probe 110 nor the eccentrically placed receiving probe 120 comes into contact with the subject E.

The transmitting probe 110 is a convergent type transmitting probe 110. On the other hand, the eccentrically arranged receiving probe 120 uses a probe with looser convergence than the transmitting probe 110. In this embodiment, the eccentrically arranged receiving probe 120 uses a non-convergent type probe with a flat probe surface. By using such a non-convergent eccentrically arranged receiving probe 120, information on the defect portion D can be collected over a wide range.

In this embodiment, the eccentrically arranged receiving probe 120 is arranged to be shifted by an eccentric distance L in the x-axis direction of FIG. 1 with respect to the transmitting probe 110, but the eccentrically arranged receiving probe 120 may be arranged to be shifted in the y-axis direction of FIG. 1. Alternatively, the eccentrically arranged receiving probe 120 may be arranged at L1 in the x-axis direction and L2 in the y-axis direction (i.e., if the position of the transmitting probe 110 on the xy plane is taken as the origin, then the position is (L1, L2)).

Figure 2A is a diagram explaining the transmission sound axis AX1, the reception sound axis AX2, and the eccentric distance L, in the case where the transmission sound axis AX1 and the reception sound axis AX2 extend vertically. Figure 2B is a diagram explaining the transmission sound axis AX1, the reception sound axis AX2, and the eccentric distance L, in the case where the transmission sound axis AX1 and the reception sound axis AX2 extend at an angle.

The sound axis is defined as the central axis of the ultrasonic beam U. Here, the transmission sound axis AX1 is defined as the sound axis of the propagation path of the ultrasonic beam U emitted by the transmission probe 110. In other words, the transmission sound axis AX1 is the central axis of the propagation path of the ultrasonic beam U emitted by the transmission probe 110. As shown in FIG. 2B, the transmission sound axis AX1 is assumed to include refraction due to the interface of the object E to be inspected. In other words, as shown in FIG. 2B, when the ultrasonic beam U emitted from the transmission probe 110 is refracted at the interface of the object E to be inspected, the center (sound axis) of the propagation path of the ultrasonic beam U becomes the transmission sound axis AX1.

The reception sound axis AX2 is defined as the sound axis of the propagation path of a virtual ultrasonic beam when it is assumed that the eccentrically disposed receiving probe 120 emits the ultrasonic beam U. In other words, the reception sound axis AX2 is the central axis of a virtual ultrasonic beam when it is assumed that the eccentrically disposed receiving probe 120 emits the ultrasonic beam U.
As a specific example, a non-focused receiving probe with a flat probe surface will be described. In this case, the direction of the receiving sound axis AX2 is the normal direction of the probe surface, and the axis passing through the center point of the probe surface becomes the receiving sound axis AX2. If the probe surface is rectangular, the center point is defined as the intersection of the diagonals of the rectangle.
The reason why the direction of the receiving sound axis AX2 is the normal direction of the probe surface is because the virtual ultrasonic beam radiated from the receiving probe is emitted in the normal direction of the probe surface. When receiving ultrasonic waves, the ultrasonic beam incident in the normal direction of the probe surface can be received with good sensitivity.

The eccentricity distance L is defined as the offset distance between the transmission sound axis AX1 and the reception sound axis AX2. Therefore, as shown in FIG. 2B, when the ultrasonic beam U emitted from the transmission probe 110 is refracted, the eccentricity distance L is defined as the offset distance between the refracted transmission sound axis AX1 and the reception sound axis AX2. In the ultrasonic inspection device Z of this embodiment, the transmission probe 110 and the eccentricity-disposed reception probe 120 are adjusted by the eccentricity distance adjustment unit 105 so that the eccentricity distance L defined in this manner is greater than zero. This reduces the ultrasonic beam U emitted from the transmission probe 110 and transmitted around the defect D, making it easier to detect signal changes originating from the defect D in the reception probe 121.

However, in this embodiment, as a preferred example, the eccentrically placed receiving probe 120 receives a scattered wave U1 generated by scattering of the ultrasonic beam U at the defect D. Because the presence of the defect D generates the scattered wave U1, the detection accuracy of the defect D can be further improved by detecting the scattered wave U1. In the following example, for the sake of simplicity, this embodiment will be described using an eccentrically placed receiving probe 120 installed at a position where it can receive the scattered wave U1.

2A shows a case where the transmitting probe 110 is arranged in the normal direction on the surface of the test object E. In FIG. 2A and FIG. 2B, the transmitting sound axis AX1 is indicated by a solid arrow. Also, the receiving sound axis AX2 is indicated by a dashed arrow. Note that in FIG. 2A and FIG. 2B, the position of the receiving probe 121 indicated by the dashed line is a position where the eccentricity distance L is zero, and the receiving probe 121 where the transmitting sound axis AX1 and the receiving sound axis AX2 coincide is a coaxially arranged receiving probe 140. Also, the receiving probe 121 indicated by the solid line is an eccentrically arranged receiving probe 120 arranged at a position with an eccentricity distance L greater than zero. When the transmitting probe 110 is installed so that the transmitting sound axis AX1 is perpendicular to the horizontal plane (xy plane in FIG. 1), the propagation path of the ultrasonic beam U is not refracted. In other words, the transmitting sound axis AX1 is not refracted.

2B is a diagram showing a case where the transmitting probe 110 is arranged at an angle α from the normal direction on the surface of the test object E. In FIG. 2B, as in FIG. 2A, the transmitting sound axis AX1 is indicated by a solid arrow, and the receiving sound axis AX2 is indicated by a dashed arrow. In the example shown in FIG. 2B, as described above, the propagation path of the ultrasonic beam U is refracted at a refraction angle β at the interface between the test object E and the air. Therefore, the transmitting sound axis AX1 is bent (refracted) as shown by the solid arrow in FIG. 2B. In this case, the position of the coaxially arranged receiving probe 140 shown by the dashed line is located on the transmitting sound axis AX1, so that the eccentric distance L is zero. And, as described above, even when the ultrasonic beam U is refracted, the eccentrically arranged receiving probe 120 is arranged so that the distance between the transmitting sound axis AX1 and the receiving sound axis AX2 is L. In the example shown in FIG. 1, the transmitting probe 110 is installed in the normal direction to the surface of the test object E, so the eccentricity distance L is as shown in FIG. 2A.

The eccentricity distance L is set at a position where the signal strength at the defective part D is greater than the signal strength at the healthy part N of the test object E. This will be described later.

Figure 3 is a functional block diagram of the control device 2. The control device 2 includes a transmission system 210, a reception system 220, a data processing unit 201, a scan controller 204, a drive unit 202, and a position measurement unit 203.

The transmission system 210 is a system that generates a voltage to be applied to the transmission probe 110. The transmission system 210 includes a waveform generator 211 and an output amplifier 212. A burst wave signal is generated by the waveform generator 211. The generated burst wave signal is then amplified by the output amplifier 212. The voltage output from the output amplifier 212 is applied to the transmission probe 110.

The receiving system 220 is a system that detects the received signal output from the eccentrically placed receiving probe 120. The signal output from the eccentrically placed receiving probe 120 is input to a signal amplifier 222 and amplified. The amplified signal is input to a waveform analysis unit 221. The waveform analysis unit 221 generates signal strength data (see FIG. 6) from the received signal, which will be described later. The generated signal strength data is sent to the data processing unit 201.

The data processing unit 201 processes the acquired information into a desired form, such as imaging information about the defect D of the object E and detecting the presence or absence of the defect D. The images and information generated by the data processing unit 201 are displayed on the display device 3.

The scan controller 204 drives and controls the transmitting probe scanning unit 103 and the receiving probe 104 shown in FIG. 1. The driving control of the transmitting probe scanning unit 103 and the receiving probe 104 is performed through the driving unit 202. In addition, the scan controller 204 measures the position information of the transmitting probe 110 and the eccentrically arranged receiving probe 120 via the position measurement unit 203.

Here, the data processing unit 201 plots and images the signal intensity data at each position based on the position information of the transmitting probe 110 and the eccentrically placed receiving probe 120 received from the scan controller 204, and displays it on the display device 3. As described below, in this embodiment, the signal intensity data acquired at the defective part D is greater than the signal intensity data of the healthy part N. Therefore, by plotting the signal intensity data against the (x, y) scanning position of the transmitting probe 110, an image can be acquired that shows where the defect is located at the (x, y) position. The image showing the defect position is displayed on the display device 3.

Figure 4 is a schematic cross-sectional view showing the structure of the transmitting probe 110. For simplicity, only the outer contour of the emitted ultrasonic beam U is shown in Figure 4, but in reality, many ultrasonic beams U are emitted in the normal vector direction of the probe surface 114 over the entire area of the probe surface 114.

The transmitting probe 110 is configured to converge the ultrasonic beam U. This allows for highly accurate detection of minute defects D in the object E. The reason why minute defects D can be detected will be described later. The transmitting probe 110 includes a transmitting probe housing 115, and a probe P inside the transmitting probe housing 115. The probe P includes a backing 112, a transducer 111, and a matching layer 113. The probe P is connected to a connector 116 by a lead wire 118. Furthermore, the connector 116 is connected to a power supply (not shown) and a control device 2 by a lead wire 117.

Figure 5A shows the received waveform from the eccentrically placed receiving probe 120, and is a diagram showing the received waveform at a healthy part N of the test object E. Figure 5B shows the received waveform from the eccentrically placed receiving probe 120, and is a diagram showing the received waveform at a defective part D of the test object E. Figure 5B shows the received signal when the transmitting probe 110 is placed at the xy coordinate position of a 2 mm wide cavity (defective part D) provided in the test object E. In Figures 5A and 5B, the time indicates the elapsed time after the burst wave is applied to the transmitting probe 110, and a stainless steel plate with a thickness of 2 mm is used as the test object E. A burst wave with a frequency of 800 kHz was applied to the transmitting probe 110. More specifically, a burst wave consisting of 10 sine waves was applied to the test object E at a constant cycle.

In FIG. 5A, no significant signal is observed, but in FIG. 5B, a significant signal is observed 90 microseconds after the burst wave is applied to the transmitting probe 110. The 90 microsecond delay until this significant signal is observed is due to the time it takes from the emission of the ultrasonic beam U to the arrival of the scattered wave U1 at the eccentrically placed receiving probe 120. Specifically, the speed of sound in air is 340 (m/s), while in the stainless steel that constitutes the test object E, it is approximately 6000 (m/s), resulting in a 90 microsecond delay.

Figure 6 is a diagram showing an example of a plot of signal strength data. In this example, the transmitting probe 110 and the eccentrically arranged receiving probe 120 are scanned in the x-axis direction for a defect D with a width of 2 mm, and the signal strength data extracted from the received signal at the x-axis position (the received signal shown in Figure 5B) is plotted. In this embodiment, the method for extracting the signal strength data is to extract the peak-to-peak value of the received signal shown in Figure 5B, that is, the difference between the maximum value and the minimum value in an appropriate time domain. As another example of a method for extracting signal strength data, the received signal shown in Figure 5B may be converted into frequency components by signal processing such as a short-time Fourier transform, and the strength of the appropriate frequency component may be extracted. Furthermore, a correlation function may be calculated as the signal strength data using an appropriate reference wave as a reference. In this way, signal strength data is obtained corresponding to each scanning position of the transmitting probe 110.

In the plot of signal intensity data shown in Figure 6, the 2 mm wide cavity (defect D) corresponds to symbol D1 in Figure 6. It can be seen that while the signal is at noise level in the healthy part N of the test object E (parts other than symbol D1), the received signal is significantly larger at the position where defect D is located inside (symbol D1).

Therefore, it is preferable that the eccentricity adjustment unit 105 adjusts the eccentricity L so that the received signal strength at the eccentrically placed receiving probe 120 when incident on the defective part D is greater than the received signal strength when incident on the healthy part N. In this way, the defective part D can be detected based on the received signal strength. Such an eccentricity L is, for example, the distance between the receiving sound axis AX2 of the eccentrically placed receiving probe 120, which is placed at a position where it can receive the scattered wave U1 (described later), and the transmitting sound axis AX1 of the transmitting probe 110. The eccentricity adjustment unit 105 is, for example, composed of an actuator, a motor, etc., neither of which are shown in the figure.

Furthermore, it is preferable that the eccentric distance adjustment unit 105 adjusts the eccentric distance L to a distance at which no received signals other than noise are detected when irradiating the healthy part N. In other words, it is preferable that the eccentric distance adjustment unit 105 sets the eccentric distance L so that no significant received signals are generated in the healthy part N of the inspected object E. In this way, the signal-to-noise ratio is increased, and the location where a received signal other than noise is detected can be determined to be a defective part D, and the defective part D can be detected.

The eccentricity distance L can be determined, for example, by using a standard specimen that is made of the same material as the specimen E and has a defect D therein. Then, an ultrasonic beam U is irradiated onto the defect D of the standard specimen, and the eccentricity distance L can be determined based on the position at which the ultrasonic beam U or the scattered wave U1 can be received.

When the transmitting probe 110 is scanned one-dimensionally in only the x-axis direction, a graph of the signal intensity data (signal intensity graph G) shown in FIG. 6 is displayed on the display device 3. When the scanning direction of the transmitting probe 110 is two-dimensional in the x-axis and y-axis directions, the signal intensity data is plotted to show the defect position as a two-dimensional image, which is then displayed on the display device 3.

Figure 7A is a diagram showing the propagation path of the ultrasonic beam U in this embodiment, when the ultrasonic beam U is incident on a healthy part N. Figure 7B is a diagram showing the propagation path of the ultrasonic beam U in this embodiment, when the ultrasonic beam U is incident on a defective part D.

As shown in Figures 7A and 7B, the ultrasonic beam U emitted from the transmitting probe 110 is incident on the test object E. As shown in Figure 7A, when the ultrasonic beam U is incident on the healthy part N, the ultrasonic beam U passes through so as to converge toward the transmission sound axis AX1. Therefore, no reception signal is observed by the eccentrically placed receiving probe 120, which is placed at an eccentric distance L. In contrast, as shown in Figure 7B, when the ultrasonic beam U is incident on the defective part D, the ultrasonic beam U is scattered by the defective part D, and the scattered wave U1 is received by the eccentrically placed receiving probe 120. Therefore, a significant reception signal is observed.

In this way, the scattered wave U1 scattered by the defect D in the object E is observed by the eccentrically placed receiving probe 120. Therefore, the received signal at the defect D is larger than the received signal at the healthy part N. In other words, it is determined that the defect D is located at the position where the signal is larger. Therefore, it is preferable for the eccentric distance adjustment unit 105 to adjust the eccentric distance L to a distance that can receive the scattered wave U1 generated by scattering of the irradiated ultrasonic beam U at the defect D of the object E. In this way, the scattered wave U1 specific to the defect D can be detected, and the detection accuracy of the defect D can be improved.

The eccentric distance L is preferably long enough to selectively receive only the scattered wave U1 without receiving the ultrasonic beam U emitted from the transmitting probe 110. This increases the signal-to-noise ratio and improves the detection performance of the defect D, particularly the detection sensitivity. Here, "high detection sensitivity" means that it is possible to detect a smaller defect D than with conventional methods. In other words, the lower limit of the size of the detectable defect D is smaller than with conventional methods.

Here, we explain a conventional ultrasonic inspection method as a comparative example.

Figure 8A is a diagram showing the propagation path of an ultrasonic beam U in a conventional ultrasonic inspection method, showing the time when it is incident on a healthy part N. Figure 8B is a diagram showing the propagation path of an ultrasonic beam U in a conventional ultrasonic inspection method, showing the time when it is incident on a defective part D. In a conventional ultrasonic inspection method, as described in Patent Document 1, for example, a coaxially arranged receiving probe 140 as a transmitting probe 110 and a receiving probe 121 is arranged so that the transmitting sound axis AX1 and the receiving sound axis AX2 coincide with each other.

As shown in FIG. 8A, when an ultrasonic beam U is incident on a healthy portion N of an object to be inspected E, the ultrasonic beam U passes through the object to be inspected E and reaches the coaxially arranged receiving probe 140. Therefore, the received signal becomes large. On the other hand, as shown in FIG. 8B, when the ultrasonic beam U is incident on a defective portion D, the defective portion D prevents the ultrasonic beam U from passing through, and the received signal decreases. In this way, the defective portion D is detected by the decrease in the received signal. This is as shown in Patent Document 1.

As shown in Figures 8A and 8B, the method of detecting a defect D by blocking the transmission of an ultrasonic beam U at the defect D, thereby reducing the received signal, is referred to here as the "blocking method." On the other hand, the inspection method of detecting a scattered wave U1 at the defect D, as in this embodiment, is referred to as the "scattering method."

Figure 9 shows plots of signal intensity data from a conventional ultrasonic inspection method. This figure is a signal intensity graph obtained by the inventors inspecting an object E having the same defect D as the object E used in Figure 6 above, using the ultrasonic inspection method using the blocking method shown in Figures 8A and 8B, i.e., an arrangement in which the transmission sound axis AX1 and the reception sound axis AX2 are aligned. In Figure 9, the part marked with the symbol D1 corresponds to the defect D.

In Figure 9, a reduction in signal is observed at the center position of the defect D (position 0 mm), but the amount of reduction is small. This is thought to be due to the fact that a large amount of the ultrasonic beam U passes through the periphery of the defect D, which is smaller than the size of the ultrasonic beam U. For this reason, with the blocking method in which the transmission sound axis AX1 and the reception sound axis AX2 are aligned, it is difficult to detect signal changes resulting from the defect D, and the detection sensitivity is low.

In contrast, by shifting the transmission sound axis AX1 and the reception sound axis AX2, the signal intensity of the ultrasonic beam U that passes around the defect D, which is smaller than the size of the ultrasonic beam U, can be reduced among the signal intensity received by the eccentrically arranged reception probe 120. This relatively increases the amount of reduction in signal intensity caused by the defect D, and improves the detection performance of the defect D, especially the detection sensitivity. In particular, as shown in FIG. 6 above, it can be seen that the configuration using the scattering method suitable for this embodiment can clearly detect the position of the defect D compared to the result of FIG. 9 using the blocking method. In other words, when comparing the reception result shown in FIG. 9, which is a comparative example, with the reception result of the method according to this embodiment shown in FIG. 6, a higher S/N ratio can be obtained with the method according to this embodiment shown in FIG. 6.

The reason why the scattering method of this embodiment can achieve a high S/N ratio will be explained with reference to Figures 10A and 10B.

Figure 10A is a diagram showing the interaction between a defect D in an object E and an ultrasonic beam U, and shows how a direct ultrasonic beam U (hereinafter referred to as a "direct wave U3") is received. The direct wave U3 will be described later. Figure 10B is a diagram showing the interaction between a defect D in an object E and an ultrasonic beam U, and shows how a scattered wave U1 is received. Here, we consider the case where the size of the defect D is smaller than the width of the ultrasonic beam U (hereinafter referred to as the beam width BW). The beam width BW here is the width of the ultrasonic beam U when it reaches the defect D.

In addition, since Fig. 10A and Fig. 10B show a schematic view of the shape of the ultrasonic beam U in a minute area near the defect D, the ultrasonic beam U is drawn parallel, but in reality, it is a converged ultrasonic beam U. Furthermore, the position of the receiving probe 121 in Fig. 10A and Fig. 10B is a conceptual position shown for easy understanding, and the position and shape of the receiving probe 121 are not scaled accurately. In other words, when considering the enlarged scale of the shape of the defect D and the ultrasonic beam U, the receiving probe 121 is located at a position farther away in the vertical direction of the drawing than the position shown in Fig. 10A and Fig. 10B. Here, the receiving probe 121 means the coaxially arranged receiving probe 140 in Fig. 10A, and the eccentrically arranged receiving probe 120 in Fig. 10B.

Even if the ultrasonic beam U is converged and incident, it has a finite width near the defect D. This is called the beam width BW at the position of the defect D. Incidentally, Figures 10A and 10B show the case where the beam width BW at the position of the defect D is wider than the size of the defect D.

Figure 10A is a diagram showing the case of the blocking method in which the transmission sound axis AX1 and the reception sound axis AX2 are aligned. If the defect D is smaller than the beam width BW, part of the ultrasonic beam U is blocked, so the received signal decreases, but does not become zero. For example, if the cross-sectional area of the defect D is 20% of the beam cross-sectional area defined by the beam width BW, the received signal decreases by only about 20%, making it difficult to detect the defect D. In other words, in the case shown in Figure 10A, the received signal decreases by only 20% at the location where the defect D exists (see Figure 9).

Figure 10B is a diagram showing a preferred method of this embodiment, that is, the scattering method. In the scattering method, if the ultrasonic beam U does not hit the defect D, the ultrasonic beam U does not enter the eccentrically placed receiving probe 120, so the received signal is zero. And, as shown in Figure 10B, even if a part of the ultrasonic beam U hits the defect D, the scattered wave U1 is observed by the eccentrically placed receiving probe 120, so it is easier to detect the defect D than the blocking method. In other words, if there is no defect D, the received signal is zero, and if there is a defect D, even if it is very small, the received signal is non-zero. Therefore, it is possible to increase the signal-to-noise ratio (see Figure 6). Thus, according to the method of this embodiment (scattering method), a defect D smaller than the beam width BW can be detected with high sensitivity. Here, "high sensitivity detection" means that a defect D smaller than the conventional method can be detected. In other words, the lower limit of the size of the detectable defect D is smaller than the conventional method.

Also, as shown in FIG. 10A, in the blocking method, the amount of received signal corresponding to the healthy part N is used as a reference, and the defective part D is judged by the amount of reduction from that. Therefore, it is preferable that the received signal at the healthy part N is a constant value. However, the strength of the ultrasonic waves that reach the receiving probe 121 is extremely small, especially in the case of ultrasonic waves propagating through gas, compared to ultrasonic waves propagating through water. Therefore, it is preferable to amplify the received signal with a high amplification factor (gain). For this reason, a high-precision signal amplifier circuit is preferable to keep the gain constant. On the other hand, in the scattering method according to this embodiment, as shown in FIG. 6, the signal is almost zero in the healthy part N, and a signal is observed in the defective part D, so the requirement for gain stability of the signal amplifier circuit can be reduced. However, in the above FIG. 6, the signal strength value is raised by only the offset value.

In addition, in this embodiment, a positive image is obtained. That is, in the scattering method, no signal is generated in the healthy area N, or even if a signal is generated, it is small, and in the defective area D, a new signal is generated or the signal becomes large. In other words, a positive image of the defective area D is obtained. In contrast, in the blocking method, the signal is large in the healthy area N, and the signal decreases in the defective area D. In other words, a negative image of the defective area D is obtained.

Furthermore, the ultrasonic inspection device Z according to this embodiment can be realized simply by shifting the position of the coaxially arranged receiving probe 140 of a conventional ultrasonic inspection device using the blocking method by the eccentric distance L. In other words, the ultrasonic inspection device that has been used up until now can be used, and installation costs can be reduced.

Figure 11 is a flow chart showing the ultrasonic inspection method of the first embodiment. The ultrasonic inspection method of the first embodiment can be performed by the ultrasonic inspection device Z described above, and will be described with reference to Figures 1 and 3 as appropriate. The ultrasonic inspection method of the first embodiment inspects the object E (Figure 1) by irradiating the object E with an ultrasonic beam U through a gas. First, an emission step S101 is performed in which an ultrasonic beam U is emitted from the transmitting probe 110 (Figure 1) in response to a command from the control device 2 (Figure 3). This is followed by a reception step S102 in which the ultrasonic beam U (scattered wave U1 in this example) is received by the eccentrically placed receiving probe 120 (Figure 1).

Then, an analysis step S103 is performed in which signal intensity data is generated based on the waveform signal of the received ultrasound beam U (scattered wave U1 in this example). The analysis step S103 is performed by the waveform analysis unit 221 (Figure 3), which extracts (generates) signal intensity data from the received signal shown in, for example, Figure 5B above. The signal intensity data can be extracted, for example, by the method described with reference to Figure 6 above. In this way, signal intensity data is obtained corresponding to each scanning position of the transmitting probe 110.

The scanning position information of the transmitting probe 110 and the eccentrically arranged receiving probe 120 is transmitted from the position measurement unit 203 (Fig. 3) to the scan controller 204 (Fig. 3). The data processing unit 201 (Fig. 3) plots the signal intensity data at each scanning position against the scanning position information of the transmitting probe 110 acquired from the scan controller 204. In this way, for example, the signal intensity graph G shown in Fig. 6 above is obtained, and the signal intensity data is visualized. Note that Fig. 6 shows a case where the scanning position information is one-dimensional (one direction). When the scanning position information is two-dimensional in x and y, the signal intensity data is plotted, and the defect position is shown as a two-dimensional image, which is displayed on the display device 3.

In addition, a judgment step S104 is performed to judge whether the signal intensity data generated in the analysis step S103 is equal to or greater than a preset threshold value, thereby judging whether or not the test object E has a defect D. The judgment step S104 is performed by the data processing unit 201. In the judgment step S104, it is judged whether or not the defect D has been detected. If the value of the generated signal intensity data is equal to or greater than a predetermined threshold value (judgment step S104, Yes), the data processing unit 201 notifies the user that the defect D has been detected (notification step S105). The processing of the notification step S105 may be performed after all scans have been completed. The notification that the defect D has been detected is displayed, for example, on the display device 3 (FIG. 3). After that, the data processing unit 201 proceeds to step S111.

If the result of the judgment step S104 is that the value of the generated signal intensity graph G is less than the predetermined threshold value (No), the data processing unit 201 judges whether the scan is complete (step S111). If the scan is complete (Yes), the control device 2 ends the process. If the scan is not complete (No), the data processing unit 201 outputs a command to the drive unit 202 (Figure 3) to move the transmitting probe 110 and the eccentrically placed receiving probe 120 to the next scanning position (step S112), and the process returns to the release step S101.

Figure 12 is a diagram showing the hardware configuration of the control device 2. The control device 2 is configured with a memory 251 such as a RAM (Random Access Memory), a CPU (Central Processing Unit) 252, a storage device 253 such as a ROM (Read Only Memory) or a HDD (Hard Disk Drive), a communication device 254 such as a NIC (Network Interface Card), an I/F (Interface) 255, etc.

Then, in the control device 2, a predetermined control program stored in the storage device 253 is loaded into the memory 251 and executed by the CPU 252. This embodies the data processing unit 201, position measurement unit 203, scan controller 204, defect information determination unit 205, waveform analysis unit 221, etc. shown in FIG. 3.

Figure 13 is a diagram showing the relationship between the transmitting probe 110 and the eccentrically placed receiving probe 120 in the ultrasound inspection device Z according to the second embodiment. In the second embodiment, the convergence relationship between the transmitting probe 110 and the eccentrically placed receiving probe 120 will be described.

In the second embodiment, the convergence of the eccentrically arranged receiving probe 120 is looser than that of the transmitting probe 110. The propagation path of the scattered wave U1 changes slightly depending on the depth of the defect D inside the object E to be inspected, the shape and inclination of the defect D, etc. Therefore, in the second embodiment, the convergence of the eccentrically arranged receiving probe 120 is looser so that the eccentrically arranged receiving probe 120 can detect the scattered wave U1 even if the path of the scattered wave U1 changes.

The magnitude relationship of the convergence is defined by the magnitude relationship of the beam incidence areas T1 and T2 on the surface of the object E to be inspected. The beam incidence areas T1 and T2 are explained below.

Figure 14 is a diagram explaining the relationship between the beam incidence area T1 in the transmitting probe 110 and the beam incidence area T2 in the eccentrically placed receiving probe 120. The beam incidence area T1 of the transmitting probe 110 is the intersection area of the ultrasonic beam U emitted from the transmitting probe 110 on the surface of the subject E. The beam incidence area T2 of the eccentrically placed receiving probe 120 is the intersection area of the virtual ultrasonic beam U2, which is assumed to be emitted from the eccentrically placed receiving probe 120, on the surface of the subject E.

In FIG. 14, the path of the ultrasonic beam U is shown when there is no object under test E. When there is an object under test E, the ultrasonic beam U is refracted at the surface of the object under test E and propagates along a path different from the path shown by the dashed line. Here, as shown in FIG. 14, the beam incidence area T2 of the eccentrically placed receiving probe 120 at the object under test E is larger than the beam incidence area T1 of the transmitting probe 110 at the object under test E. In this way, the convergence of the eccentrically placed receiving probe 120 can be made looser than that of the transmitting probe 110.

Furthermore, the focal length R2 of the eccentrically arranged receiving probe 120 is longer than the focal length R1 of the transmitting probe 110. In this way, the convergence of the eccentrically arranged receiving probe 120 can be made looser than the convergence of the transmitting probe 110. In this case, the distance from the test subject E to the transmitting probe 110 and the eccentrically arranged receiving probe 120 is, for example, the same for both, but does not have to be the same.

In this way, in the second embodiment, the convergence of the eccentrically arranged receiving probe 120 is looser than the convergence of the transmitting probe 110. That is, the focal length R2 of the eccentrically arranged receiving probe 120 is set longer than the focal length R1 of the transmitting probe 110. As a result, the beam incidence area T2 of the eccentrically arranged receiving probe 120 is wider, so that a wide range of scattered waves U1 can be detected. This makes it possible for the eccentrically arranged receiving probe 120 to detect the scattered waves U1 even if the propagation path of the scattered waves U1 changes slightly. As a result, a wide range of defective portions D can be detected.

The focal point of the eccentrically placed receiving probe 120 is located closer to the transmitting probe 110 (above in the illustrated example) than the focal point of the transmitting probe 110. By shifting the focal point in this manner, it becomes easier for the eccentrically placed receiving probe 120 to receive the scattered wave U1, and easier to detect the scattered wave U1.

The eccentrically arranged receiving probe 120 may be a non-converging probe as used in the first embodiment. In a non-converging probe, the focal length R2 is infinite, so it is longer than the focal length R1 of the transmitting probe 110. In other words, even in the case of a non-converging eccentrically arranged receiving probe 120, the convergence of the eccentrically arranged receiving probe 120 is weaker than the convergence of the transmitting probe 110.

Figure 15 is a diagram showing an example of an eccentrically arranged receiving probe 120 according to the third embodiment. It is a plan view of the ultrasonic inspection device Z, with the transmitting probe 110 and the eccentrically arranged receiving probe 120 viewed from the negative side of the z-axis. In other words, it is a view seen from the eccentrically arranged receiving probe 120 side. In the third embodiment, the length b of the transducer 111 (Figure 4) of the eccentrically arranged receiving probe 120 in the eccentric direction of the receiving sound axis AX2 relative to the transmitting sound axis AX1 is longer than the length a in the direction along the surface of the test object E and perpendicular to the eccentric direction. The lengths a and b are characteristic lengths, which mean the lengths of the sides of a rectangle for a rectangular transducer, and mean the major axis or minor axis of an ellipse for an elliptical transducer.

By setting the aspect ratio of the eccentrically placed receiving probe 120 in this manner, even if the depth of the defect D changes and the arrival position of the scattered wave U1 changes, the scattered wave U1 can be detected by the eccentrically placed receiving probe 120.

The scattered wave U1 is scattered in the radial direction around the transmission sound axis AX1. Therefore, when the eccentrically placed receiving probe 120 is placed at the position shown in FIG. 15, the scattered wave U1 is scattered in the longitudinal direction of the eccentrically placed receiving probe 120 (the extension direction of "length b"). In other words, the extension direction of "length b" is the direction in which the scattered wave U1 is emitted. Therefore, by increasing the value of "length b", it is possible to detect the scattered wave U1 scattered at defects D of various depths, etc. In other words, even if the depth, etc. of the defect D changes and the arrival position of the scattered wave U1 changes, the scattered wave U1 can be detected by the eccentrically placed receiving probe 120.

There is no restriction on the lengths a and b, and it is sufficient that the length b is longer than the length a, i.e., 1<b/a, but the upper limit of b/a (length b divided by length a) is, for example, 100 or less, and preferably 50 or less.

In FIG. 15, an eccentrically placed receiving probe 120 having a rectangular parallelepiped (rectangular) shape is illustrated as the eccentrically placed receiving probe 120, but the same effect can be obtained by making it elliptical and setting the major axis/minor axis ratio in the same way.

Figure 16 is a diagram showing the configuration of the scanning measurement device 1 of the ultrasonic inspection device Z according to the fourth embodiment. In the fourth embodiment, the scanning measurement device 1 includes an installation angle adjustment unit 106 that adjusts the inclination of the eccentrically placed receiving probe 120. This increases the strength of the received signal and increases the signal-to-noise ratio (SNR) of the signal. The installation angle adjustment unit 106 is, for example, configured by an actuator, a motor, etc., neither of which are shown in the figure.

Here, the angle θ between the transmission sound axis AX1 and the reception sound axis AX2 is defined as the reception probe installation angle. In the case of FIG. 16, the transmission probe 110 is installed vertically, so the transmission sound axis AX1 is vertical, and the angle θ, which is the reception probe installation angle, is the angle between the transmission sound axis AX1 (i.e., the vertical direction) and the normal to the probe surface of the eccentrically arranged reception probe 120. Then, the installation angle adjustment unit 106 tilts the angle θ toward the side where the transmission sound axis AX1 exists, and sets the angle θ to a value greater than zero. That is, the eccentrically arranged reception probe 120 is tilted. Specifically, the eccentrically arranged reception probe 120 is tilted so as to satisfy 0°<θ<90°, and the angle θ is, for example, 10°, but is not limited to this.

The eccentric distance L when the eccentrically positioned receiving probe 120 is tilted is defined as follows. An intersection C2 between the receiving sound axis AX2 and the eccentrically positioned receiving probe 120 (probe) is defined. An intersection C1 between the transmitting sound axis AX1 and the transmitting probe 110 (probe P) is defined. The eccentric distance L is defined as the distance between the coordinate position (x1, y1) obtained by projecting the position of intersection C1 onto the xy plane, and the coordinate position (x2, y2) obtained by projecting the position of intersection C2 onto the xy plane.

When the inventors actually tried to detect defect D by tilting the eccentrically positioned receiving probe 120 in this way, the signal strength of the received signal increased threefold.

Figure 17 is a diagram explaining why the effect of the fourth embodiment is produced. The scattered wave U1 propagates in a direction deviating from the transmission sound axis AX1. Therefore, as shown in Figure 17, when the scattered wave U1 reaches the outside of the test object E, it is incident on the test object E-external interface at a non-zero angle α2 with the normal vector of the test object E surface. The angle of the scattered wave U1 emerging from the surface of the test object E has an angle β2, which is a non-zero exit angle with respect to the normal direction of the test object E surface. The scattered wave U1 can be received most efficiently when the normal vector of the probe surface of the eccentrically arranged receiving probe 120 is aligned with the traveling direction of the scattered wave U1. In other words, the received signal strength can be increased by tilting the eccentrically arranged receiving probe 120.

In addition, from the structure shown in FIG. 17, the reception effect is highest when the angle β2 of the ultrasonic beam U emitted from the subject E coincides with the angle θ between the transmission sound axis AX1 and the reception sound axis AX2. However, even if the angle β2 and the angle θ do not coincide perfectly, the effect of increasing the reception signal can be obtained, so as shown in FIG. 17, the angle β2 and the angle θ do not have to coincide perfectly.

In addition, the scanning measurement device 1 in FIG. 16 above is provided with an installation angle adjustment unit 106, and the eccentrically placed receiving probe 120 is installed by the installation angle adjustment unit 106. The installation angle adjustment unit 106 can adjust the receiving probe installation angle of the eccentrically placed receiving probe 120. Since the path of the scattered wave U1 changes slightly depending on the material, thickness, etc. of the test object E, the optimal value of the receiving probe installation angle also changes. Therefore, by making the receiving probe installation angle adjustable by the installation angle adjustment unit 106, the receiving probe installation angle can be appropriately adjusted depending on the material, thickness, etc. of the test object E.

In the fourth embodiment, the eccentrically arranged receiving probe 120 is arranged at an incline with respect to the horizontal plane, but the transmitting probe 110 may also be arranged at an incline. Alternatively, the transmitting probe 110 may be arranged at an incline with respect to the horizontal plane, and the probe surface of the eccentrically arranged receiving probe 120 may be arranged so as to be parallel to the horizontal plane (xy plane). In either case, as shown in FIG. 2B above, the transmitting sound axis AX1 and the receiving sound axis AX2 are arranged in a shifted state.

Figure 18 is a diagram showing the configuration of an ultrasonic inspection device Z according to the fifth embodiment. In the fifth embodiment, the eccentrically arranged receiving probe 120 includes multiple unit probes 120a. In the illustrated example, there are three unit probes 120a. The unit probes 120a are each arranged at positions with different eccentric distances L (distance from the transmission sound axis AX1).

The path of the scattered wave U1 changes slightly depending on the depth, shape, inclination, etc. of the defect D. For example, the scattering angle (the angle that the scattered wave U1 makes with respect to the transmission sound axis AX1) is usually about the same, so the deeper the defect D, the closer the scattered wave U1 will reach from the transmission sound axis AX1, and the shallower the defect D, the farther the scattered wave U1 will reach from the transmission sound axis AX1. Therefore, by using multiple unit probes 120a and using information on which unit probe 120a received the signal, information about the defect D (such as the depth of the defect D) can be obtained.

As the multiple unit probes 120a, an array type probe 122 (described later with reference to Figures 28 and 29) in which multiple sound sensor elements 122a are housed in one housing may be used. In this case, each unit probe 120a in Figure 18 corresponds to a sound sensor element, and they are housed in one housing. A sound sensor element is an element that converts ultrasonic waves into an electrical signal. As the sound sensor element, in addition to a piezoelectric element, a capacitive sound sensor element (CMUT, Capacitive Micro-machined Ultrasonic Transducer) or the like may be used.

Figure 19 is a functional block diagram of an ultrasonic inspection device Z according to the fifth embodiment. A plurality of unit probes 120a are connected to corresponding receiving systems 220a to 220c. The configuration of each of the receiving systems 220a to 220c is similar to the configuration of the receiving system 220 shown in Figure 3. The output from each of the receiving systems 220a to 220c is input to the defect information determination unit 205.

The defect information determination unit 205 is provided in the control device 2, and determines information about the defect D in the object E (such as the depth of the defect D) based on the reception signal of the unit probe 120a among the multiple unit probes 120a that receives the scattered wave U1 generated by scattering of the irradiated ultrasonic beam U at the defect D of the object E. Specifically, the defect information determination unit 205 determines information about the defect D based on the waveform analysis results in each of the receiving systems 220a to 220c. "Based on the reception signal" refers to which unit probe 120a detected how much of the reception signal (scattered wave U1). In this way, the accuracy of the position information of the defect D can be improved.

The output of the defect information determination unit 205 is input to the data processing unit 201. In the data processing unit 201, the information on the defect D is imaged and displayed on the display device 3 by combining it with position information from the scan controller 204 that scans the probe.

The defect information determination unit 205 may be provided as part of the data processing unit 201.

Figure 20 is a diagram showing the arrangement of the eccentrically arranged receiving probe 120 in the sixth embodiment. In this example, the transmitting probe 110 and the eccentrically arranged receiving probe 120 are shown in a plan view as viewed from the negative side of the z axis in Figure 1, i.e., the eccentrically arranged receiving probe 120 side. In the sixth embodiment, the eccentrically arranged receiving probe 120 is arranged two-dimensionally in the xy plane direction. That is, the eccentrically arranged receiving probe 120 includes a plurality of unit probes 120a that are rectangular in plan view, and the plurality of unit probes 120a are arranged radially around the transmitting sound axis AX1. In the example shown, there are eight unit probes 120a.

The direction of the scattered wave U1 varies slightly depending on the shape and tilt direction of the defect D. Therefore, by arranging the unit probes 120a radially as shown in Figure 17 and recording the direction in which the scattered wave U1 was detected, information on the shape and tilt direction of the defect D can be obtained with greater accuracy.

Figure 21 shows the arrangement of the eccentrically arranged receiving probe 120 in the seventh embodiment, in which the unit probes 120a are arranged at an angle. A plurality of unit probes 120a are arranged symmetrically with respect to the transmission sound axis AX1. Therefore, at least two unit probes 120a are arranged at positions with the same eccentric distance L. In the illustrated example, three unit probes 120a are arranged symmetrically on both sides of the transmission sound axis AX1 in a plan view including the transmission sound axis AX1. Two unit probes 120a are arranged at each of three different eccentric distances L. The unit probes 120a are arranged at an angle, similar to the fourth embodiment (Figure 17) described above.

Figure 22 shows the arrangement of the eccentrically arranged receiving probe 120 in the seventh embodiment, with the unit probes 120a arranged in the vertical direction. A set of unit probes 120a are arranged symmetrically with respect to the transmission sound axis AX1. Therefore, at least two unit probes 120a are arranged at positions with the same eccentricity distance L.

By arranging at least two unit probes 120a at positions with the same eccentricity distance L, it is possible to detect scattered waves U1 scattered in multiple directions. Furthermore, by arranging at least two unit probes 120a on both sides of the transmission sound axis AX1 in a plan view including the transmission sound axis AX1 (Figures 21 and 22), it is possible to receive scattered waves U1 over a wide range. Furthermore, when the control device 2 detects scattered waves U1 with the unit probes 120a on both sides, it can actually detect a defect D, and if the scattered waves U1 are detected by only one of the unit probes, it can determine that an error has occurred. This can improve the detection accuracy of the defect D.

Figure 23 is a diagram showing the configuration of an ultrasonic inspection device Z in the eighth embodiment. In the eighth embodiment, the receiving probe 121 includes, in addition to the eccentrically arranged receiving probe 120, a coaxially arranged receiving probe 140 arranged at a position where the eccentricity distance L is zero. The coaxially arranged receiving probe 140 is provided in the scanning measurement device 1, and is arranged so as to coincide with the transmission sound axis AX1 and the reception sound axis AX2. In this specification, the receiving probe 121 arranged at a position where the eccentricity distance L is zero is called the coaxially arranged receiving probe 140.

The scanning measurement device 1 includes a coaxially arranged receiving probe 140 in addition to the configuration of the first embodiment (FIG. 1). The eccentrically arranged receiving probe 120 can be moved by the eccentric distance adjustment unit 105 to a position where it can receive the scattered wave U1, independently of the coaxially arranged receiving probe 140. When scanning the test object E, the transmitting probe 110, the eccentrically arranged receiving probe 120, and the coaxially arranged receiving probe 140 move together by the movement of the transmitting probe scanning unit 103 and the receiving probe scanning unit 104 in the xy plane. The output signal of the coaxially arranged receiving probe 140 is input to the control device 2.

As shown in FIG. 8B above, the coaxially arranged receiving probe 140 receives a signal by the blocking method. Therefore, when there is a defect larger than the convergence diameter of the ultrasonic beam U, a reduction in the received signal is observed, and the defect can be detected. On the other hand, for defects smaller than the convergence diameter of the ultrasonic beam U, the defect D can be detected by observing the scattered wave U1 with the eccentrically arranged receiving probe 120. Therefore, by providing the eccentrically arranged receiving probe 120 and the coaxially arranged receiving probe 140, in addition to being able to detect defect D smaller than the diameter of the ultrasonic beam U, it is also possible to detect defect D larger than the diameter of the ultrasonic beam U.

Figure 24 is a functional block diagram of an ultrasonic inspection device Z in the eighth embodiment. The output signal of the eccentrically arranged receiving probe 120 is input to the receiving system 220a. The output signal of the coaxially arranged receiving probe 140 is input to the receiving system 220b. The output signals of the receiving systems 220a and 220b are each input to the defect information determination unit 205. The defect information determination unit 205 uses the two received signals to determine the presence or absence of a defect D, and outputs the result to the data processing unit 201.

A specific example of the processing method of the defect information determination unit 205 will be described. For the received signal from the eccentrically arranged receiving probe 120, it is determined that the defect D exists at the scanning position where the signal increases by a certain amount. For the received signal from the coaxially arranged receiving probe 140, it is determined that the defect D exists at the position where the signal decreases by a certain amount. The logical sum of the determinations based on the two signals is the output of the defect information determination unit 205. In other words, if a defect is determined to exist based on either the determination based on the received signal from the eccentrically arranged receiving probe 120 or the determination based on the received signal from the coaxially arranged receiving probe 140, the defect information determination unit 205 determines that a defect D exists.

By providing an eccentrically arranged receiving probe 120 and a coaxially arranged receiving probe 140, it is possible to reduce the number of missed detections of defective areas D and improve detection performance.

Figure 25 is a diagram showing the configuration of the defect information determination unit 205 of the ultrasonic inspection device Z of the ninth embodiment. In the ninth embodiment, for example, the ultrasonic inspection device Z shown in Figure 23 can be used, and minute defects are detected using an interference signal generated by combining the signal of the direct wave U3 observed by the coaxially arranged receiving probe 140 and the signal of the scattered wave U1 received by the eccentrically arranged receiving probe 120.

The defect information determination unit 205 includes an interference signal generation unit 231, a scattered wave feature extraction unit 232a, a direct wave feature extraction unit 232b, an interference signal feature extraction unit 232c, and a signal integration processing unit 240. First, the output signal of the receiving system 220a and the output signal of the receiving system 220b are both input to the interference signal generation unit 231. The interference signal generation unit 231 is provided in the control device 2 and synthesizes the output signal (scattered wave U1 signal) of the eccentrically arranged receiving probe 120 and the output signal (direct wave U3 signal) of the coaxially arranged receiving probe 140. Since the phases of the scattered wave U1 and the direct wave U3 generated in the defect part D are different, they cancel each other out in the interference signal generated by the synthesis, and the signal change amount in the defect part D becomes large. As a result, it is possible to detect a smaller defect D than the conventional blocking type that observes the signal change amount of the direct wave U3.

Here, the principle of how the interference signal is generated will be explained with reference again to Figures 10A and 10B above. Figure 10A shows a schematic of the propagation path of the direct wave U3 received by the coaxially arranged receiving probe 140. Figure 10B shows a schematic of the propagation path of the scattered wave U1 received by the eccentrically arranged receiving probe 120.

Assume that the size (diameter) of the defect D is smaller than the beam diameter of the transmitted ultrasonic beam U. Figures 10A and 10B are schematic diagrams assuming such a case. In this case, as shown in Figure 10A, part of the ultrasonic beam U emitted from the transmitting probe 110 (Figure 1) is blocked by the defect D, but the direct wave U3 that is not blocked by the defect D is incident on the coaxially arranged receiving probe 140. In contrast, as shown in Figure 10B, the scattered wave U1 scattered by the defect D is incident on the eccentrically arranged receiving probe 120. As shown in Figure 10B, the scattered wave U1 has a different propagation path from the ultrasonic beam U incident on the coaxially arranged receiving probe 140, and therefore the wave phase is different. In addition, the wave phase changes during the process of scattering by the defect D.

In this way, the ultrasonic waves received by the coaxially arranged receiving probe 140 and the ultrasonic waves received by the eccentrically arranged receiving probe 120 have different wave phases. Therefore, when the two received signals are appropriately combined, they cancel each other out. Appropriate combination here refers to combination that reflects the phase, and includes, for example, combination by Fourier transform in the frequency domain, but among these, signal combination in the time domain is preferable. In other words, it is preferable for the interference signal generator 231 to perform signal combination in the time domain. Combination in the time domain allows for easy combination.

Figure 26A is a diagram showing the change at the measurement point of the reception signal A received by the coaxially arranged receiving probe 140. Figure 26B is a diagram showing the change at the measurement point of the reception signal B received by the eccentrically arranged receiving probe 120. Figure 26C is a diagram showing the change at the measurement point of the interference signal C synthesized by the interference signal generating unit 231. In these figures, the horizontal axis is the x-coordinate of the measurement position, the vertical axis is the maximum amplitude, and the case where the defect D exists at the position x = 0 is shown.

The received signal A received by the coaxially arranged receiving probe 140 (Fig. 10A) decreases at the position of the defect D (x = 0; the same applies below). The received signal B received by the eccentrically arranged receiving probe 120 (Fig. 10B) corresponds to the scattered wave U1, and therefore increases at the position of the defect D. The interference signal C, which is a combination of the two, decreases more than the received signal A alone due to the interference effect of the received signals A and B, which are out of phase at the position of the defect D. Therefore, the received signal B of the scattered wave U1 increases at the position of the defect D (Fig. 26B), but the interference signal C output from the interference signal generator 231 decreases at the position of the defect D (Fig. 26C). The degree of decrease is greater than that of the received signal A of the coaxially arranged receiving probe 140 (Fig. 26A).

In this way, by combining the reception signal of the coaxially arranged receiving probe 140 and the reception signal of the eccentrically arranged receiving probe 120 in the interference signal generating unit 231, the amount of signal change caused by the defect D can be increased, and the detection performance, especially the detection sensitivity, can be improved.

Returning to FIG. 25, the output signal of the receiving system 220a and the output signal of the receiving system 220b are further input to the scattered wave feature extraction unit 232a and the direct wave feature extraction unit 232b, respectively. The scattered wave feature extraction unit 232a extracts a feature derived from the defect D from the signal waveform of the scattered wave U1. The direct wave feature extraction unit 232b extracts a feature derived from the defect D from the signal waveform of the direct wave U3. The extraction of the feature is, for example, extraction of the maximum signal amplitude in an appropriate delay time range taking into account the signal delay time, feature extraction in the frequency domain such as short-time Fourier transform or wavelet transform, etc.

The output signal of the interference signal generation unit 231 is input to the interference signal feature extraction unit 232c. The interference signal feature extraction unit 232c extracts features originating from the defect D from the waveform of the generated interference signal in the same manner as the scattered wave feature extraction unit 232a and the direct wave feature extraction unit 232b.

The output signals (extracted features) obtained by the scattered wave feature extraction unit 232a, the direct wave feature extraction unit 232b, and the interference signal feature extraction unit 232c are input to the signal integration processing unit 240. The signal integration processing unit 240 determines that a defect D exists at the position where the feature was extracted. The signal integration processing unit 240 outputs the position where it is determined that a defect D exists to the data processing unit 201.

The defect information determination unit 205 can detect defects D from large to small, improving detection accuracy.

The scattered wave feature extraction unit 232a, the direct wave feature extraction unit 232b, and the interference signal feature extraction unit 232c may output to the data processing unit 201 without going through the signal integration processing unit 240. With this configuration, it becomes possible to visualize multiple types of defect images based on three types of information, so that more information about the defect D can be obtained.

Figure 27 is a diagram showing the configuration of an ultrasonic inspection device Z of the tenth embodiment. In the tenth embodiment, the focal length R3 of the coaxially arranged receiving probe 140 is shorter than the focal length R2 of the eccentrically arranged receiving probe 120. This makes the convergence of the coaxially arranged receiving probe 140 higher than the convergence of the eccentrically arranged receiving probe 120.

By making the focal length R3 of the coaxially arranged receiving probe 140 shorter than the focal length R2 of the eccentrically arranged receiving probe 120, the coaxially arranged receiving probe 140 can efficiently receive the ultrasonic beam U on the receiving sound axis AX2 of the ultrasonic beam U emitted from the transmitting probe 110. On the other hand, since the scattered wave U1 has multiple propagation paths, the eccentrically arranged receiving probe 120 that receives it can sufficiently receive the scattered wave U1 by reducing the convergence. Therefore, defects can be detected more efficiently by using a receiving probe 121 that has convergence that matches the characteristics of the direct wave U3 and the scattered wave U1.

Figure 28 is a diagram showing the configuration of an ultrasonic inspection device Z of the 11th embodiment. In the 11th embodiment, an array type probe 122 is used that has the functions of both an eccentrically arranged receiving probe 120 and a coaxially arranged receiving probe 140. The array type probe 122 is a receiving probe 121 in which multiple sound sensor elements 122a (which also function as unit probes 120a (Figure 18)) are arranged one-dimensionally (Figure 28) or two-dimensionally (Figure 29 described below).

The array-type probe 122 is arranged so that the receiving sound axis AX2 of one of the constituent sound sensor elements 122a coincides with the transmitting sound axis AX1. The sound sensor element 122a arranged in this position functions as a coaxially arranged receiving probe 140. The remaining sound sensor elements 122a are arranged continuously and symmetrically in the left-right direction of the paper in FIG. 28 centered on the transmitting sound axis AX1, as in the example shown in FIG. 18 above, and function as eccentrically arranged receiving probes 120. In this example, the sound sensor elements 122a are arranged one-dimensionally.

By using the array probe 122 and arranging the sound sensor elements 122a one-dimensionally, the number of sound sensor elements 122a installed is reduced, reducing the installation cost of the array probe 122, and the scattered wave U1 can be received by multiple sound sensor elements 122a. Even if the defect D is small and ultrasonic propagation is completely blocked, the sound sensor element 122a having the receiving sound axis AX2 that coincides with the transmitting sound axis AX1 can detect the decrease in the signal amount. This allows efficient detection of defects D from small to large.

Figure 29 is a diagram showing the configuration of an ultrasonic inspection device Z of the twelfth embodiment. Figure 29 is a plan view of the transmitting probe 110 and the array probe 122 as viewed from the negative side of the z axis in Figure 1, that is, from the side of the array probe 122. In Figure 28 above, the sound sensor elements 122a constituting the array probe 122 are arranged one-dimensionally in only one direction. However, in the array probe 122 shown in Figure 29, the sound sensor elements 122a are arranged two-dimensionally in two directions, x and y. In the example shown, the sound sensor elements 122a are arranged in equal numbers (seven elements each) in each of the x and y directions, and are arranged in a square shape. However, the sound sensor elements 122a are not limited to being arranged in a square shape, and may be arranged in various shapes, such as a rectangle, a circle, or an ellipse.

By using the array probe 122 and arranging the acoustic elements 122a two-dimensionally, the scattered wave U1 can be received by many acoustic elements 122a, and the missed detection of the scattered wave U1 can be suppressed. Even if the defect D is small and ultrasonic propagation is completely blocked, the acoustic element 122a having the receiving sound axis AX2 that coincides with the transmitting sound axis AX1 can detect the decrease in the signal amount. This allows efficient detection of defects D from small to large.

In each of the above embodiments, an example is described in which the defect D is a cavity, but the defect D may also be a foreign body containing a material different from the material of the object E to be inspected. In this case, too, there is a difference (Gap) in acoustic impedance at the interface where the different materials come into contact, so scattered waves U1 are generated, and the configuration of this embodiment is therefore effective. The ultrasonic inspection device Z according to this embodiment is based on an ultrasonic defect imaging device, but may also be applied to a non-contact in-line internal defect inspection device.

The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

The above-mentioned configurations, functions, and each part constituting the block diagram may be realized in hardware, for example, by designing some or all of them as an integrated circuit. As shown in FIG. 22, the above-mentioned configurations, functions, and the like may be realized in software by a processor such as CPU 252 interpreting and executing a program that realizes each function. In addition to being stored in the HD, information such as the programs, tables, and files that realize each function can be stored in a recording device such as memory 251 or SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, SD (Secure Digital) card, or DVD (Digital Versatile Disc).

In addition, in each embodiment, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other.

REFERENCE SIGNS LIST 1 Scanning measurement device 101 Housing 102 Sample stage 103 Transmitting probe scanning section 104 Receiving probe scanning section 105 Eccentric distance adjustment section 106 Installation angle adjustment section 110 Transmitting probe 111 Transducer 112 Backing 113 Matching layer 114 Probe surface 115 Transmitting probe housing 116 Connectors 117, 118 Lead wire 120 Eccentrically arranged receiving probe (receiving probe)
120a unit probe 121 receiving probe 122 array type probe (transmitting probe, receiving probe)
122a: Sound sensor element 140: Coaxially arranged receiving probe (receiving probe)
2 Control device 201 Data processing unit 202 Driving unit 203 Position measurement unit 204 Scan controller 205 Defect information judgment unit 210 Transmission system 211 Waveform generator 212 Output amplifier 220, 220a, 220b, 220c Reception system 221 Waveform analysis unit 222 Signal amplifier 231 Interference signal generation unit 232a Scattered wave feature amount extraction unit 232b Direct wave feature amount extraction unit 232c Interference signal feature amount extraction unit 240 Signal integration processing units A, B Reception signal AX1 Transmission sound axis AX2 Reception sound axis C Interference signal D Defect section
E: Object to be inspected L; Eccentricity distance N: Healthy part P; Probes R1, R2, R3; Focal length S101; Emission step S102; Reception step S103; Analysis step S104; Judgment step S105; Notification steps T1, T2; Beam incidence area U, U2; Ultrasonic beam U1; Scattered wave U3; Direct wave Z; Ultrasonic inspection device

Claims (20)

1. An ultrasonic inspection apparatus for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
a scanning and measuring device that scans and measures the object to be inspected with the ultrasonic beam, and a control device that controls driving of the scanning and measuring device,
The scanning measurement device is
a transmitting probe for emitting the ultrasonic beam;
an eccentrically disposed receiving probe disposed on the opposite side of the transmitting probe with respect to the object to receive the ultrasonic beam;
the eccentrically arranged receiving probe is arranged so that an eccentric distance between a transmission sound axis of the transmitting probe and a reception sound axis of the eccentrically arranged receiving probe is greater than zero ;
An ultrasonic inspection apparatus in which the focal length of the eccentrically disposed receiving probe is longer than the focal length of the transmitting probe . 2. The ultrasonic inspection device according to claim 1, wherein the eccentricity distance is set to a distance at which scattered waves generated by scattering of the ultrasonic beam at a defect portion of the object to be inspected can be received. 2. The ultrasonic inspection device according to claim 1, wherein the eccentric distance is set so that the strength of the received signal at the eccentrically placed receiving probe when incident on a defective portion of the object to be inspected is greater than the strength of the received signal when incident on a healthy portion of the object to be inspected. 2. The ultrasonic inspection device according to claim 1, wherein the eccentric distance is set to a distance at which no received signal other than noise is detected when a healthy portion of the object to be inspected is irradiated. 2. The ultrasonic inspection apparatus according to claim 1, further comprising an eccentricity adjustment unit for adjusting the position of at least one of the transmitting probe and the eccentrically disposed receiving probe. 1. An ultrasonic inspection apparatus for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
a scanning and measuring device that scans and measures the object to be inspected with the ultrasonic beam, and a control device that controls driving of the scanning and measuring device,
The scanning measurement device is
a transmitting probe for emitting the ultrasonic beam;
an eccentrically disposed receiving probe disposed on the opposite side of the transmitting probe with respect to the object to receive the ultrasonic beam;
the eccentrically arranged receiving probe is arranged so that an eccentric distance between a transmission sound axis of the transmitting probe and a reception sound axis of the eccentrically arranged receiving probe is greater than zero;
An ultrasonic inspection apparatus, characterized in that a focal point of the eccentrically disposed receiving probe is located closer to the transmitting probe than a focal point of the transmitting probe. 2. The ultrasonic inspection device according to claim 1, wherein a beam incidence area of the eccentrically disposed receiving probe on the object to be inspected is larger than a beam incidence area of the transmitting probe on the object to be inspected. 2. The ultrasonic inspection device according to claim 1, wherein the scanning measurement device includes an installation angle adjustment unit that adjusts an inclination of the eccentrically disposed receiving probe so that an angle θ between the transmitting sound axis and the receiving sound axis satisfies 0°<θ<90°. 2. The ultrasonic inspection apparatus according to claim 1, wherein the eccentrically disposed receiving probe includes a plurality of unit probes. The ultrasonic inspection device according to claim 9, characterized in that the control device includes a defect information determination unit that determines information regarding a defect in the object to be inspected based on a reception signal of a unit probe among the plurality of unit probes that receives a scattered wave generated by scattering of the irradiated ultrasonic beam at a defect in the object to be inspected. The ultrasonic inspection device according to claim 9 , wherein the plurality of unit probes are arranged radially around the sound transmission axis. The ultrasonic inspection device according to claim 9 , wherein at least two of the unit probes are arranged at positions with the same eccentricity distance. The ultrasonic inspection device according to claim 1, characterized in that the length of the transducer of the eccentrically arranged receiving probe in the eccentric direction of the receiving sound axis relative to the transmitting sound axis is longer than the length in a direction along the surface of the object to be inspected and perpendicular to the eccentric direction. 10. The ultrasonic inspection apparatus according to claim 1 , wherein the scanning measurement device includes a coaxially arranged receiving probe arranged at a position where the eccentricity distance is zero. 1. An ultrasonic inspection apparatus for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
a scanning and measuring device that scans and measures the object to be inspected with the ultrasonic beam, and a control device that controls driving of the scanning and measuring device,
The scanning measurement device is
a transmitting probe for emitting the ultrasonic beam;
an eccentrically disposed receiving probe disposed on the opposite side of the transmitting probe with respect to the object to receive the ultrasonic beam;
a coaxially arranged receiving probe arranged at a position where the eccentricity between the transmission sound axis of the transmitting probe and the reception sound axis of the eccentrically arranged receiving probe is zero,
the eccentrically disposed receiving probe is disposed such that the eccentric distance is greater than zero;
An ultrasonic inspection device, characterized in that a focal length of the coaxially arranged receiving probe is shorter than a focal length of the eccentrically arranged receiving probe. 1. An ultrasonic inspection apparatus for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
a scanning and measuring device that scans and measures the object to be inspected with the ultrasonic beam, and a control device that controls driving of the scanning and measuring device,
The scanning measurement device is
a transmitting probe for emitting the ultrasonic beam;
an eccentrically disposed receiving probe disposed on the opposite side of the transmitting probe with respect to the object to receive the ultrasonic beam;
a coaxially arranged receiving probe arranged at a position where the eccentricity between the transmission sound axis of the transmitting probe and the reception sound axis of the eccentrically arranged receiving probe is zero,
the eccentrically disposed receiving probe is disposed such that the eccentric distance is greater than zero;
The ultrasonic inspection device according to claim 1, wherein the control device includes an interference signal generating unit that combines an output signal of the eccentrically arranged receiving probe and an output signal of the coaxially arranged receiving probe. The ultrasonic inspection device according to claim 16 , wherein the interference signal generating unit performs signal synthesis in the time domain. 1. An ultrasonic inspection method for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
An emission step of emitting an ultrasonic beam from a transmitting probe;
a receiving step of receiving the ultrasonic beam with an eccentrically disposed receiving probe that is disposed on the opposite side of the transmitting probe with respect to the object under test , has a receiving sound axis at a position different from the transmitting sound axis of the transmitting probe, and has a focal length longer than that of the transmitting probe ;
an analysis step of generating signal intensity data based on the received ultrasonic beam signal;
1. An ultrasonic inspection method comprising: 20. The ultrasonic inspection method according to claim 18, further comprising a determination step of determining whether or not the signal intensity data generated in the analysis step is equal to or greater than a preset threshold value, thereby determining whether or not the object to be inspected has a defect. 1. An ultrasonic inspection method for inspecting an object to be inspected by irradiating an ultrasonic beam onto the object to be inspected through a gas, comprising:
An emission step of emitting an ultrasonic beam from a transmitting probe;
a receiving step of receiving the ultrasonic beam with an eccentrically disposed receiving probe that is disposed on the opposite side of the transmitting probe with respect to the object under test, has a receiving sound axis at a position different from the transmitting sound axis of the transmitting probe, and has a focal point that is located on the transmitting probe side relative to the focal point of the transmitting probe;
an analysis step of generating signal intensity data based on the received ultrasonic beam signal;
1. An ultrasonic inspection method comprising:

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