Inspection device and inspection method

Abstract

To provide an inspection device which offers superior directivity and is capable of handling complex shapes.SOLUTION: An inspection device 1 provided herein comprises impactors 3 and two or more reception units 4, and is configured to have N combinations of the impactors 3 and the two or more reception units 4 to allow some or all of the impactors 3 to collide simultaneously with an inspection target object 10 so as to generate a plane wave Q.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an inspection device using an impact elastic wave method or a hammering acoustic method, which is used for non-destructive inspection, particularly for inspecting defects such as voids formed inside a product. [Background technology]

[0002] X-ray and ultrasonic flaw detectors are well-known non-destructive testing methods for industrial materials and parts. For example, X-ray devices irradiate the object under test with X-rays and detect the intensity of the transmitted X-rays to visualize the object's internal structure. Transmittance varies depending on the density and thickness of the material, and measuring and imaging this allows for the detection of abnormalities and defects. Ultrasonic testing devices emit ultrasonic waves from a transducer, some of which are reflected by the surface of the object under test, while the rest travel through the object. When ultrasonic waves pass through different media, some are reflected. The strength of the reflection varies depending on the medium. When the medium is air, almost all of the waves are reflected. Therefore, in the case of a defective product containing a cavity, the presence of a void can be detected because the amount of reflection from the cavity differs from that of a passing product.

[0003] Patent Document 1 discloses a material defect detection method in which an impact is applied to a material to be measured, vibrations generated in the material are measured, and defects in the material are detected from the frequency spectrum of the vibrations obtained by Fourier transform.

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 4-95872 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional hammering sound methods such as those disclosed in Patent Document 1 have the problem that the location of flaws cannot be identified in one test. Furthermore, X-ray devices are expensive and require a long inspection time, making them difficult to make profitable. Furthermore, ultrasonic flaw detection devices require a certain amount of surface area for ultrasonic waves to enter, so while they are not a problem for parts with simple shapes, they are difficult to apply to parts with complex shapes, such as those with uneven surfaces, and the long inspection time required poses a problem. This tendency is particularly pronounced for large die-cast products. The present invention provides an inspection device that solves these problems. [Means for solving the problem]

[0006] Therefore, the present invention provides an inspection device for an impact elastic wave method or an impact sound method, which is equipped with an impactor and a receiving unit, wherein the impactor is capable of exciting elastic waves by colliding with an object to be inspected, the receiving unit is made up of a receiver or a microphone, and 2 to X combinations of the impactor and two or more receiving units are arranged.

[0007] The present invention is also characterized in that at least a plurality of the impactors are provided, and the collision actions of the plurality of impactors can be performed simultaneously.

[0008] At least a plurality of the impactors are provided, The impactors are divided into groups 1 to N, and the collision actions of the impactors belonging to group 1 can be performed simultaneously, and the collision actions of the impactors belonging to group N can be performed simultaneously, the impactors belonging to group 1 are arranged at a fixed distance from each other, and the impactors belonging to group N are arranged at a fixed distance from each other, and the collision actions of the impactors belonging to group 1 and the impactors belonging to group N can be performed at different times.

[0009] Furthermore, the present invention is characterized in that the objects to be inspected that are the targets of the inspection device are all of the same type, and further includes a holding device that holds the objects to be inspected, and the holding device is capable of holding the objects to be inspected by aligning the impactor so that it is located at the same position on the part of the object to be inspected for all of the objects to be inspected of the same type.

[0010] In addition, in the present invention, the inspection device further includes an information processing unit, which is capable of checking whether or not there is a defect by comparing normal data obtained from the receiving unit by inspecting an object to be inspected whose integrity has been confirmed or data obtained by analyzing and converting the normal data with data obtained from the receiving unit by inspecting the object to be inspected or data obtained by converting the normal data.

[0011] The inspection method of the present invention also includes a collision step in which an impactor performs a collision operation to generate elastic waves in the object to be inspected; a receiving step in which a receiving unit receives the elastic waves, estimates the presence or absence of a flaw and its depth and direction, and transmits estimated position information; a beamforming collision step in which the impactor performs a collision operation again to generate elastic waves in the object to be inspected; and a beamforming step in which the receiving unit is controlled to receive the elastic waves generated by the beamforming collision step so as to increase the sound collection sensitivity around the depth and direction indicated in the estimated position information and decrease the sound collection sensitivity at other depths and directions, and is characterized in that the beamforming collision step and the beamforming step are carried out after at least the collision step and the receiving step. [Effects of the Invention]

[0012] The present invention provides an inspection device for the impact elastic wave method or the impact sound method, which is equipped with an impactor and a receiving unit. The impactor can generate elastic waves by colliding with the object to be inspected, and the receiving unit is made up of a receiver or a microphone. The device is characterized in that 2 to X combinations of impactors and two or more receiving units are arranged, so that the device can be applied to objects to be inspected with complex shapes and can improve the accuracy of flaw detection.

[0013] Furthermore, the present invention is characterized in that it is equipped with at least a plurality of impactors, and the collision actions of the plurality of impactors can be performed simultaneously. Therefore, it is possible to provide an inspection device that can be applied to inspection objects with complex shapes and can improve the accuracy of flaw detection.

[0014] The present invention also provides a vehicle equipped with at least a plurality of impactors, the plurality of impactors being divided into groups 1 to N, the impactors belonging to group 1 being capable of performing the collision actions simultaneously, and the impactors belonging to group N being capable of performing the collision actions simultaneously, the impactors belonging to group 1 being arranged at a fixed distance from each other, The impactors belonging to the N groups are positioned at a fixed distance from each other, and the collision actions of the impactor belonging to group 1 and the impactor belonging to group N can be carried out at different times. This makes it possible to provide an inspection device that can be applied to inspection objects with complex shapes and can improve the accuracy of flaw detection.

[0015] Furthermore, the present invention is characterized in that all of the objects to be inspected by the inspection device are of the same type, and furthermore, the device is equipped with a holding device for holding the object to be inspected, and the holding device is capable of holding the object to be inspected by aligning the impactor so that it is located at the same position on the part of the object to be inspected for all objects of the same type.Therefore, an inspection device can be provided that can be applied to objects to be inspected with complex shapes and can improve the accuracy of flaw detection.

[0016] In addition, in the present invention, the inspection device further comprises an information processing unit, which is characterized in that it is possible to confirm the presence or absence of defects by comparing normal data obtained from the receiving unit by inspecting an object to be inspected whose integrity has been confirmed, or data obtained by analyzing and converting this, with data obtained from the receiving unit by inspecting the object to be inspected, or data obtained by converting this, and therefore it is possible to provide an inspection device that can easily estimate the presence or absence of defects.

[0017] Furthermore, the inspection method of the present invention comprises a collision step in which an impactor is used to perform a collision operation to generate elastic waves in the object to be inspected; a receiving step in which a receiving unit receives the elastic waves to estimate the presence or absence of a flaw, as well as its depth and direction, and transmits estimated position information; a beamforming collision step in which the impactor is used to perform a collision operation again to generate elastic waves in the object to be inspected; and a beamforming step in which the receiving unit is controlled to increase the sound collection sensitivity around the depth and direction indicated in the estimated position information and decrease the sound collection sensitivity at other depths and directions, thereby receiving the elastic waves generated by the beamforming collision step.The beamforming collision step and the beamforming step are carried out after at least the collision step and the receiving step, and therefore an inspection device can be provided that is applicable to objects to be inspected with complex shapes and can improve the accuracy of flaw detection. [Brief explanation of the drawings]

[0018] [Figure 1] 1A and 1B are diagrams showing examples of a portion of the inspection device 1 of the present invention, where (W) is a plan view showing a case where there are two receiving units 4 for one impactor, (X) is a plan view showing a case where there are three receiving units 4 for one impactor, (Y) is a plan view showing a case where there are four receiving units 4 for one impactor, and (Z) is a plan view showing a case where there are six receiving units 4 for one impactor. [Figure 2] 1 is a diagram showing an inspection device 1 as an example of an embodiment of the present invention. [Figure 3] 1 is an explanatory diagram showing the principle of inspection performed by the inspection device 1 according to the present embodiment using an impact elastic wave method. [Figure 4] This is an explanatory diagram showing the inspection performed by the impact elastic wave method using the inspection device 1 of this embodiment, where (X) shows the inspection of a normal object 10, and (Y) shows the inspection of a defective object 10' having a flaw 12. [Figure 5] 1 is an explanatory diagram showing the inspection performed by the inspection device 1 according to the present embodiment using an impact elastic wave method. [Figure 6]FIG. 1 is a diagram showing an inspection device 2 as another example of an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing grouping of impactors 3 in an inspection device 2 that is another example of an embodiment of the present invention, where (X) shows the first group and (Y) shows the second group. [Figure 8] 10A and 10B are diagrams showing grouping of impactors 3 in an inspection device 2 that is another example of an embodiment of the present invention, where (X) shows the third group and (Y) shows the fourth group. [Figure 9] 10A and 10B are diagrams showing an inspection when a microphone 6 is covered with a sound-insulating material 13 as another example of an embodiment of the present invention, where (X) shows the state before the inspection and (Y) shows the state during inspection by the impact sound method. [Figure 10] FIG. 1 is a flow chart showing an example of an embodiment of an inspection method 20 of the present invention. [Figure 11] 10A and 10B are diagrams showing the state of the inspection device during the beam forming collision process 23 of the present invention, where (X) is an explanatory diagram showing when the impactor 3 collides with the object to be inspected 10, and (Y) is an explanatory diagram showing when the impactor 33 collides with the object to be inspected 10 after the impactor 3. DETAILED DESCRIPTION OF THE INVENTION

[0019] Detailed descriptions of embodiments of the present invention will be given below with reference to the drawings. First, an inspection device and an inspection method using the impact acoustic wave method or the impact sound method according to this embodiment will be described. FIG. 1 is a diagram showing an example of a portion of an inspection device 1 according to the present invention, where (W) is a plan view showing a combination of impactors 3 and receivers 4 in which two receivers 4 are provided for one impactor, (X) is a plan view showing a combination of three receivers 4 for one impactor, (Y) is a plan view showing a combination of four receivers 4 for one impactor, and (Z) is a plan view showing a combination of six receivers 4 for one impactor. FIG. 2 is a diagram showing an inspection device 1 as an example of an embodiment of the present invention. FIG. 2(X) shows an inspection device 1 in which the receivers 4 are arranged on the outside so that there are four receivers 4 per impactor, and (Y) shows an inspection device 1' in which there is a mixture of three and four receivers 4 per impactor. Both of these are according to this embodiment. FIG. 3 is an explanatory diagram showing an inspection using the impact elastic wave method by the inspection device 1 according to this embodiment, where (X) shows the state before the inspection and (Y) shows the impactor 3 colliding with the object 10 during the inspection. FIG. 4 is an explanatory diagram showing an inspection using the impact elastic wave method by the inspection device 1 according to this embodiment, where (X) shows the inspection of a normal object 10 and (Y) shows the inspection of a defective object 10' having a flaw 12. FIG. 5 is an explanatory diagram showing an inspection using the impact elastic wave method by the inspection device 1 according to this embodiment, illustrating the generation of elastic waves by three aligned impactors 3. FIG. 6 is a diagram showing an inspection device 2 having 24 impactors 3 as another example of an embodiment of the present invention. FIG. 7 is a diagram showing the grouping of the impactors 3 in the inspection device 2 according to the present invention shown in FIG. 6, where the white circles in (X) represent the first group and the white circles in (Y) represent the second group. FIG. 8 is a diagram showing the grouping of the impactors 3 in the inspection device 2 of the present invention shown in FIG. 6, where the white circles (X) indicate the third group and the white circles (Y) indicate the fourth group.FIG. 9 is a diagram showing an example of another embodiment of the present invention, in which an impact sound inspection is performed when a microphone 6 is covered with a sound-insulating material 13. (X) shows the state before the inspection, and (Y) shows the state when the impactor 3 collides with the object under test 10. FIG. 10 is a flowchart showing an example of an embodiment of an inspection method 20 of the present invention. FIG. 11 is an explanatory diagram showing the beamforming collision step 23, which is part of the inspection method 20 of the present invention. (X) shows the state when the impactor 3 collides with the object under test 10, and (Y) shows the state when the impactor 33 collides with the object under test 10 after (X). Note that the receiving unit 4 is not shown in FIGS. 7 and 8. Furthermore, in this disclosure, for convenience of explanation, when simply referring to the upper side, it refers to the upper side in FIGS. 3, 4, 9, and 11, and when simply referring to the lower side, it refers to the lower side in FIGS. 3, 4, 9, and 11. Also, Figures 1, 2, 6, 7 and 8 are views from above.

[0020] FIG. 1 is a diagram showing an example of a portion of an inspection device 1 according to the present invention. The inspection device 1 according to the present invention includes multiple combinations of impactors 3 and receivers 4. FIG. 1 illustrates one of these combinations. First, as shown in FIG. 1(W), a receiver 4 may be provided on a circular dashed auxiliary line centered on the impactor 3. Alternatively, as shown in FIG. 1(X), three receivers 4 may be provided at equiangular positions on the circular dashed auxiliary line centered on the impactor 3. Alternatively, as shown in FIG. 1(Y), four receivers 4 may be provided in the same manner as in (W) and (X), or six receivers 4 may be provided in the same manner as in (Z). Note that the dashed lines shown in FIG. 1 are auxiliary lines for explanation purposes, showing the positional relationship between the impactor 3 and the receivers 4. In all of FIG. 1, the distance between the impactor 3 and each receiver 4 is equal, and the spacing between adjacent receivers 4 is also equal. This configuration is preferable as it simplifies calculations when using the inspection device 1, but it is not limited to this, and the distance between the impactor 3 and each receiving unit 4 and the spacing between adjacent receiving units 4 may all be configured differently.

[0021] Next, the inspection apparatus 1, 1' of the present invention will be described in detail with reference to FIG. 2. First, FIG. 2(X) shows an example of the inspection apparatus 1 according to this embodiment. In FIG. 2(X), 32 combinations of impactors 3 and receivers 4 are arranged in the arrangement shown in FIG. 1(Y). As shown in FIG. 2(X), one combination of impactor 3 and receiver 4 and another adjacent combination of impactor 3 and receiver 4 may be configured using the same receiver 4. In this way, by using multiple combinations of impactors 3 and receivers 4, the location of a hollow flaw 12 inside the object to be inspected 10 can be estimated, which is preferable.

[0022] Next, referring to FIG. 2(Y), an inspection device 1' will be described as another example of this embodiment. Similar to the inspection device 1 shown in FIG. 2(X), the inspection device 1' has 32 combinations of impactors 3 and receivers 4 arranged in an array. The arrangement includes a mixture of the combination of one impactor 3 and four receivers 4 shown in FIG. 1(Y) and the combination of one impactor 3 and three receivers 4. Adjacent combinations of impactors 3 and multiple receivers 4 are configured using the same receivers 4. As shown in FIG. 2(Y), the number of receivers 4 may differ between the combinations of impactors 3 and receivers 4. In this way, the inspection device 1, 1' configured with 2 to N combinations of impactors 3 and multiple receivers 4 is preferable because it facilitates identifying the location of a cavity-like flaw 12 inside the object 10 to be inspected.

[0023] Next, the principle of the inspection devices 1, 1', and 2 of the present invention will be explained with reference to Figure 3. First, the receiving unit 4 is composed of a receiver 5 or a microphone 6, but in Figure 3, the receiver 5 will be used for explanation. Figure 3(X) is a diagram showing a part of the inspection devices 1, 1', and 2 of the present invention, illustrating the state before the impactor 3 collides with the object to be inspected 10. The impactor 3 collides with the object to be inspected 10 in the direction of the arrow shown in Figure 3(X). Figure 3(Y) shows the state at the time of collision. When the impactor 3 collides with the object to be inspected 10, an elastic wave is generated in the direction of the linear arrow shown in Figure 3(Y). The elastic wave is reflected at the boundary surface with the air. This elastic wave enters the receiver 5 and is received. At this time, if a hollow flaw 12 is present, the elastic wave will return earlier. Note that when elastic waves are received by a receiver 5 that is in close contact with the object under test 10, it is called the impact elastic wave method, and when they are received by a microphone 6 that is not in close contact with the object under test 10, as shown in Figure 9, it is called the impact acoustic method. Furthermore, the elastic waves that are generated at the moment the impactor 3 collides with the object under test 10 in point contact are actually reflected not just once, but repeatedly while attenuating. Since the object under test 10 often does not have a simple shape, even the first reflection produces a complex reflected sound according to the shape.

[0024] Next, the principle of the inspection devices 1, 1', and 2 of the present invention will be described in more detail with reference to Figure 4. Figure 4(X) shows the case where two receivers 5 are arranged on either side of the impactor 3. When the impactor 3 collides, elastic waves are generated in the directions of the arrows on lines N and L. Figure 4(X) shows the case where a normal inspection object 10 without a flaw 12 is inspected using the inspection devices 1, 1', and 2 of the present invention. In contrast, Figure 4(Y) shows the case where an inspection object 10' with a hollow flaw 12 is inspected using the inspection devices 1, 1', and 2 of the present invention.

[0025] As shown in Figures 4(X) and 4(Y), elastic waves are generated in a normal inspection object 10 as shown by line L, but in an inspection object 10' with a hollow flaw 12, elastic waves are generated as shown by line M. Elastic waves are generated in both inspection objects 10 and 10' as shown by line N. These waves are received by the receiver 5. As a result, different elastic waves are generated in the inspection object 10 and the inspection object 10' as shown by lines L and M. Since the distances between lines L and M are different, the receiver 5 receives the elastic waves at different times. Furthermore, since the thickness of the part passing through line M is thinner than that of line L, the resonant frequency is higher. From this information, the direction and depth of the flaw 12 can be estimated. The elastic waves generated by the impactor 3 are in the ultrasonic to audible range.

[0026] An information processing unit (not shown) provided in the inspection devices 1, 1', and 2 according to the present invention records a large amount of data from the receiver 5 or microphone 6 as normal data for an object to be inspected that has been confirmed to be free of defects, such as the object to be inspected 10 shown in FIG. 4(X). This normal data is then compared with the data received by the receiver 5 or microphone 6 in the case of FIG. 4(Y), thereby identifying a defective product with a flaw 12. Difference may be used as a method for comparison. The data received by the receiver 5 or microphone 6 during inspection may be directly compared with the stored normal data and then analyzed, or the results of the data analysis may be compared with the analysis results of the normal data.

[0027] Since the speed of sound slows as the temperature of the object to be inspected 10 increases, it is preferable to correct the normal data according to the temperature during inspection by the inspection devices 1, 1', and 2, since this can reduce errors by correcting the normal data before using it. Furthermore, for analyzing the sound data, the fast Fourier transform (FFT), short-time Fourier transform (STFT), wavelet transform, Wigner distribution, etc. are used as needed. By selecting and combining these analysis methods according to the purpose, a flaw signal indicating the presence of a flaw 12 can be obtained.

[0028] Next, the principles of the inspection apparatuses 1, 1', and 2 of the present invention will be described in more detail with reference to FIG. 5. FIG. 5 is a conceptual diagram showing how elastic waves propagate when an impactor 3 collides with an object under test 10. When the impactor 3 collides with the object under test 10, waves O and P are generated. These waves O and P are combined to form a composite wave Q. This composite wave Q then propagates as a plane wave. The generation of a plane wave increases the directionality of the elastic wave compared to when only waves O and P are present. For this reason, the inspection apparatuses 1, 1', and 2 of the present invention preferably include at least a plurality of impactors 3. It is more preferable that multiple impactors 3 be configured to collide with the object under test 10 simultaneously, as shown in FIG. 5. However, this is not limiting, and multiple impactors 3 may be configured to collide with the object under test 10 at different times.

[0029] Next, the impact operation of the impactor 3 will be described in detail. The impactor 3 generates elastic waves by colliding with the object 10 to be inspected, and inspects the object 10. In this case, in the inspection devices 1, 1', and 2 according to the present invention, the impactor 3 may be capable of performing the impact operation one to eight times in succession. When performing the impact operation two or more times, it is preferable that the interval between the impact operations is 5 milliseconds or less, since this shortens the inspection time and ensures a sufficient resonance effect. An interval of 1 millisecond or less is more preferable.

[0030] Next, an inspection device 2 will be described in detail as another example of an embodiment of the present invention, with reference to Fig. 6. As shown in Fig. 1(Z), the inspection device 2 is equipped with 24 combinations, each of which uses six receivers 4 per impactor 3. Adjacent combinations of impactor 3 and receiver 4 use the same receiver 4. The receiver 4 uses a receiver 5 or a microphone 6.

[0031] Next, referring to FIG. 7, the inspection device 2 will be described in further detail as another example of an embodiment of the present invention. FIG. 7(X) shows the inspection device 2 shown in FIG. 6. In FIG. 7(X), the impactor 3′ that is impacting the object under inspection 10 is indicated by a white circle. The impactor 3 that is not impacting the object under inspection 10 is indicated by a black circle. The impactors 3′ are spaced apart from each other to perform their impacting operations. This space is preferably 100 mm or more and 200 mm or less, since it prevents mutual interference between the elastic waves generated by the impactors 3′. To avoid mutual interference, staggering the operation of nearby impactors rather than operating them at different times may increase the likelihood of overlooking small defects, making this approach preferable.

[0032] Simultaneous operation of the impactors 3' produces a plane wave-like effect for flaw detection, which tends to enhance directionality and is therefore preferable. In Figures 7(Y), 8(X), and 8(Y), impactors 3' that are impacting the object under test 10 are indicated by open circles and represent impactors 3'. Impactors 3 that are not impacting the object under test 10 are indicated by black circles and represent impactors 3. Thus, it is preferable to divide the impactors 3, 3' into four groups, such as the group of impactors 3' in Figure 7(X), the group of impactors 3' in Figure 7(Y), the group of impactors 3' in Figure 8(X), and the group of impactors 3' in Figure 8(Y), and perform impact operations with a fixed interval between the impactors 3, 3' within each group. In other words, it is preferable to divide the inspection device 2 into N groups, each containing a group of multiple impactors 3, and perform impact operations with a fixed interval between the impactors 3, 3' within each group. 7 and 8, the inspection device 2 includes a receiving unit 4 similar to that in FIG. 6, but this is omitted for ease of explanation.

[0033] The impactors 3 may be divided into groups, and the operations shown in Figure 7(X), Figure 7(Y), Figure 8(X), and Figure 9(Y) may be performed at different times. By arranging multiple impactors 3 at regular intervals in a group such as a polygonal shape, mutual interference between elastic waves generated by impactors 3' operating simultaneously can be prevented, which is preferable.

[0034] Alignment of the object to be inspected 10 is important because normal data, which is data of a healthy object to be inspected and pre-registered in the information processing unit provided in the inspection devices 1, 1', and 2 according to the present invention, will produce different sound data and cannot be used for comparison unless the impactor 3 comes into contact with the object to be inspected 10 at the same location when it collides with the object to be inspected 10. The object to be inspected 10 can be aligned by using a mechanism that holds the object to be inspected 10 so that it does not move, or by moving the impactor 3 to align it with the object to be inspected 10, and these methods can be used depending on the purpose.

[0035] If the object 10 to be inspected is small, a mechanism that holds the object 10 so that it does not move is preferable, and if the object 10 to be inspected is large, it may be better for the impactor 3 to move and align with the object 10 to be inspected. If the inspection range of the impactor 3 cannot cover the entire object 10 to be inspected, that is, if the impactor 3 needs to move multiple times to cover the inspection range, it is preferable for the impactor 3 to move and align with the object 10 to be inspected, as described above. Furthermore, even if the test object 10 is large, the test object 10 may be held so that it does not move, and the impactor 3 may move to inspect an area where the test range of the test object 10 does not cover the test object 10. When moving the test object 10 while holding it, the stopping position must be moved with high precision so as not to shift. Furthermore, whether the test object 10 is being held or not, it is preferable to use sound-absorbing material for all contact with the test object 10, as this blocks external sounds and allows stable sound data to be obtained.

[0036] Next, referring to FIG. 9, we will describe in detail the case where the receiver 4 of the inspection device 1, 1', or 2 according to the present invention is a microphone 6. FIG. 9(X) illustrates the state before impact, with the impactor 3 performing a collision in the direction of the arrow. FIG. 9(Y) illustrates the state after the collision, with the straight arrow indicating an elastic wave. When an elastic wave enters the microphone 6, the microphone 6 may not receive the elastic wave properly due to ambient noise or other factors. For this reason, it is preferable to cover the microphone 6 with a sound-insulating material 13 and to configure it in close contact with the object under test 10. Furthermore, for low-frequency ambient noise, noise reduction may be achieved by superimposing a sound with an opposite phase to the ambient sound. Covering the microphone with a sound-insulating material 13 is effective for high-frequency sounds with short wavelengths and linear propagation, but for low-frequency sounds with long wavelengths, the sound-insulating material 13 has a low noise attenuation effect and the sound travels around the object, making it less effective. For this reason, it is preferable to cancel low-frequency ambient noise by generating an anti-phase sound from a speaker (not shown) to overlap the anti-phase sound with the ambient noise, or to cancel the noise by calculating the received data with the anti-phase ambient sound data. When canceling by calculation, the received data received by the microphone 6 may be used, or the analysis result data obtained by analyzing the received data using various analysis methods may be used.

[0037] Furthermore, beamforming technology may be used when using the receiving unit 4. By using beamforming to process the output sounds of multiple receiving units 4, the sound collection sensitivity may be increased in the desired direction and decreased in other directions. When multiple impactors 3 are used to simultaneously perform impact operations on the object 10 under test, plane waves are emitted, increasing directivity, so it is more preferable to use beamforming technology in the direction of this directivity to increase the sound collection sensitivity in the desired direction and decrease it in other directions. It is also preferable to estimate the position of the flaw 12, operate the impactor 3 again, and use beamforming technology in the direction where the flaw 12 is estimated to be located.

[0038] Here, the beamforming control unit for performing the beamforming step 24 will be described in detail. The beamforming control unit is composed of a mixing unit that forms the directional characteristics of the multiple receiving units 4 and a steering unit that steers the beam toward the desired direction. The beamforming control unit uses these units to process the output information of the multiple receiving units 4, thereby controlling the sound pickup sensitivity of the multiple receiving units 4 so that it is high in the desired direction and low in other directions.

[0039] Next, an inspection method 20 using an acoustic impact method or an impact elastic wave method, which can use the inspection devices 1, 1', and 2 according to the present invention, will be described in detail. The inspection method 20 according to the present invention comprises a collision step 21 and a receiving step 22. The inspection method 20 according to the present invention may further comprise a beamforming collision step 23 and a beamforming step 24. These will be described in detail next with reference to FIG. 10.

[0040] The collision step 21 according to the present invention shown in FIG. 10 is a step of causing the impactor 3 to collide with the test object 10 (step 1), as shown in FIGS. 3, 4, 5, and 9. By causing the impactor 3 to collide with the test object 10, elastic waves are generated in the directions of the arrows of lines N and L, as shown in FIG. 4(X), for example. In the collision step 21, the impactor 3 may be configured to perform the collision operation one to eight times in succession. When performing two or more collision operations, the interval between the collision operations is preferably 5 milliseconds or less, as this shortens the inspection time and ensures a sufficient resonance effect. An interval of 1 millisecond or less is more preferable.

[0041] Next, a receiving step 22 is carried out in which the generated elastic waves are received by the receiving unit 4 and position information data is output (step 2). The receiving unit 4 may use a receiver 5 or a microphone 6. In the receiving step 22, after the elastic waves are received by the receiving unit 4, the information processing unit performs a comparison operation between normal data and the data received by the receiving unit 4 to identify defective products having flaws 12 and output position estimation information, which is information that estimates the depth and position of the flaws 12.

[0042] Next, a beamforming collision step 23 is performed in which the impactor 3 is again collided with the object under test 10 to generate elastic waves in the object under test (step 3). In the beamforming collision step 23, when elastic waves are generated by the collision action of colliding the impactor 3 with the object under test 10, the timing of the collision of the impactors 3, 33 may be shifted as shown in Figures 11(X) and 11(Y). Therefore, in the beamforming collision step 23, estimated position information may be input to the beamforming control unit, and the impactors 3, 33 may be controlled so as to send stronger elastic waves by shifting the collision actions of the impactors 3, 33 with respect to the direction and depth indicated by the estimated position information. In Figure 11, for ease of explanation, the impactor 3 and impactor 33 are shown separately, but the impactor 33 is shown as the same as the impactor 3. FIG. 11(X) shows the impactor 3 colliding with the object under test 10, and FIG. 11(Y) shows the impactor 33 colliding with the object under test 10 with a delay. By causing the impactors 3 to collide with the object under test 10 simultaneously and then causing the impactors 33 to collide with the object under test 10 at different times, it is possible to send stronger elastic waves in a specific direction. The interval for shifting the timing is preferably 100 nanoseconds to 10 microseconds after the impactor 3 has collided. Based on the estimated position information output by the receiving process 22, the beamforming control unit controls the impactors 3 and 33, controlling the timing of the impacting operation of the impactors 3 and 33 so as to send stronger elastic waves in the direction and depth indicated by the estimated position information. This makes it possible to send stronger elastic waves to the position of the flaw 12 estimated in the receiving process 22, thereby improving the accuracy of detecting the position and depth of the flaw 12.

[0043] Referring to Figure 11, the impact of the impactor 33, which is timed to collide after the impactor 3, will be described in more detail. Figure 11(X) is an explanatory diagram illustrating the impact of the impactor 3. At this point, the impactor 33 has not yet collided. An elastic wave R is generated by the impactor 3's collision. Next, Figure 11(Y) is shown. Figure 11(Y) illustrates the impact of the impactor 33 after the impact of the impactor 3. In addition to the elastic wave R generated by the impact of the impactor 3, an elastic wave S is generated by the impactor 33 colliding with the test object 10. The elastic waves R and S are then combined to generate a composite wave (not shown). The composite wave has a larger amplitude than the area directly below the impactor 33, resulting in a stronger wave. In the region T indicated by the dashed circle in Figure 11, the amplitude of the composite wave of the elastic waves R and S is approximately three times larger, resulting in a stronger wave. By shifting the timing of impactor 3 and impactor 33 in this way, it becomes possible to send stronger elastic waves in a specific direction.

[0044] In the beam forming collision step 23, elastic waves are generated again by causing the impactors 3, 33 to collide with the object 10 to be inspected. After the impactor 3 collides with the object 10 to be inspected, the action of the impactor 33 colliding with the object 10 to be inspected is counted as one collision, and the impactors 3, 33 may be able to perform collision actions one to eight times in succession. When performing collision actions two or more times, it is preferable that the interval between collision actions is 5 milliseconds or less, because this shortens the inspection time and ensures a sufficient resonance effect. An interval of 1 millisecond or less is more preferable.

[0045] Next, a beamforming step 24 is performed in which the receiver 4 is controlled to receive the elastic waves generated by the beamforming collision step 23 so as to increase the sound collection sensitivity around the depth and direction indicated in the estimated position information and decrease the sound collection sensitivity at other depths and directions (step 3). In the beamforming step 24, the estimated position information is input to the beamforming control unit, and the beamforming control unit controls the receiver 4 so as to increase the sound collection sensitivity around the depth and direction indicated in the estimated position information and decrease the sound collection sensitivity at other depths and directions. The controlled receiver 4 then receives the elastic waves generated by the beamforming collision step 23 and outputs the received information. The information processing unit again compares this received information with normal data and performs an operation, thereby making it possible to more accurately estimate the depth and position of the flaw 12.

[0046] 10 , the inspection method 20 according to the present invention may sequentially perform the collision step 21, the reception step 22, the beamforming collision step 23, and the beamforming step 24. However, the timing of the beamforming collision step 23 may partially overlap the time series of the beamforming collision step 24. For example, before the beamforming collision step 23 is performed, estimated position information may be input to the beamforming control unit, and the beamforming control unit may control the reception unit 4 so as to increase the sound collection sensitivity around the depth and direction indicated in the estimated position information and decrease the sound collection sensitivity at other depths and directions. Thereafter, the impactor 3 may perform a collision operation again in the beamforming collision step 23. However, it is necessary that the beamforming collision step 23 and the beamforming collision step 24 are performed at least after the collision step 21 and the reception step 22.

[0047] The present disclosure can be suitably used for the purpose of inspecting die-cast products, castings, etc. made of aluminum or the like, particularly of complex shapes, as the inspection object 10. However, the present disclosure is not limited to this, and can be widely used in the inspection of products that require flaw detection. [Explanation of symbols]

[0048] 1,1´,2,Inspection equipment 3. Impactor 4. Receiving unit 5, Geson 6. Microphone 10. Inspection object 11,Surface 12. Flaw (cavity) 13. Sound insulation material 20. Inspection method 21, Collision process 22. Receiving process 23. Beamforming collision process 24. Beamforming process

Claims

1. An inspection device for an impact elastic wave method or an impact acoustic method, which is equipped with an impactor and a receiving unit, the impactor is capable of exciting elastic waves by colliding with the test object; the receiving unit comprises a receiver or a microphone, A combination of the impactor and two or more of the receiving units, An inspection device characterized by being arranged in 2 to X units.

2. At least a plurality of the impactors are provided, 2. The inspection device according to claim 1, wherein the collision actions of the plurality of impactors can be performed simultaneously.

3. At least a plurality of the impactors are provided, The impactors are divided into groups 1 to N, and the collision actions of the impactors belonging to group 1 can be performed simultaneously, and the collision actions of the impactors belonging to group N can be performed simultaneously, the impactors belonging to the first group are arranged at a fixed distance from each other, the impactors belonging to the N groups are arranged at a fixed distance from each other, 2. The inspection device according to claim 1, wherein the collision operations of the impactor belonging to the first group and the impactor belonging to the Nth group can be performed at different times.

4. 2. The inspection device according to claim 1, wherein the objects to be inspected by the inspection device are all of the same type, and further comprising a holding device for holding the objects to be inspected, the holding device being capable of holding the objects to be inspected by positioning the impactor so that it is located at the same position on the part of the object to be inspected for all of the objects to be inspected of the same type.

5. The inspection device further includes an information processing unit, The inspection device according to claim 1, characterized in that the information processing unit is capable of checking whether or not there is a defect by comparing normal data obtained from the receiving unit by inspecting an object to be inspected that has been confirmed to be healthy, or data obtained by analyzing and converting the normal data, with data obtained from the receiving unit by inspecting the object to be inspected, or data obtained by converting the normal data.

6. a collision step in which an impactor performs a collision operation to generate elastic waves in the test object; a receiving step of receiving the elastic waves by a receiving unit, estimating the presence or absence of a flaw, its depth and direction, and transmitting estimated position information; a beam forming collision step in which a collision operation by the impactor is performed again to generate elastic waves in the test object; A beamforming process for receiving the elastic waves generated by the beamforming collision process by controlling the receiving unit so that the sensitivity of sound collection is increased around the depth and direction indicated in the estimated position information and the sensitivity of sound collection is decreased at other depths and directions, An inspection method, characterized in that after at least the collision step and the receiving step, the beamforming collision step and the beamforming step are performed.

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