JP4262046B2 - Sound inspection system - Google Patents

Description

  The present invention relates to a hammering inspection system including a hitting tool and a defect detection device that detects and detects a defect of an inspection target by collecting and analyzing a hitting sound generated by hitting the inspection target with the hitting tool. .

  In recent years, diagnosis of mechanical equipment such as motors and compressors has been performed by analyzing sound signals emitted from them. In such a case, it is important how accurately the sound signal is captured, and various proposals have been made about this (for example, see Patent Document 1).

  By the way, the object to be inspected is hit with a striking tool, and the sound (hereinafter referred to as the hitting sound) generated at the time of hitting is collected by a microphone and analyzed to analyze a cavity or the like existing inside the object to be inspected. A hitting sound inspection system that detects a defect is known (see, for example, Non-Patent Document 1, Patent Document 2, and Patent Document 3).

In Non-Patent Document 1, an impulse hammer that can output a striking force with voltage or the like is used as a striking tool, and the sound generated when the concrete on the tunnel is struck with this impulse hammer has a stethoscope shape. A sound-inspecting system that collects sound with a microphone surrounded by a hood has been proposed. In this system, the maximum voltage value obtained from an impulse hammer for each impact and the sound that is collected by the microphone along with this is recorded. The defective portion is determined based on the ratio with the maximum sound pressure value.
Japanese Patent No. 3223237 'Inspection Technology', July 2002, 41-45 (Technical Topics / Architecture / Civil Engineering) JP-A-5-322861 JP 2002-333437 A

  However, in the sound inspection system proposed in Non-Patent Document 1, Patent Document 2, and Patent Document 3, in addition to the sound wave directed to the sound receiving surface of the microphone without being reflected by the inner wall of the hood, the inner wall of the hood In addition, sound waves that are reflected only once and then go to the microphone or sound waves that have been reflected multiple times on the inner wall of the hood are collected, so these sound waves interfere with each other, so that the accuracy of defect detection in the inspection object is improved. There is a decline.

  In addition, since it is difficult to give the microphone surrounded by the hood an appropriate directivity, in order to avoid the influence of surrounding acoustic noise as much as possible, the hood opening should be in close contact with the inspection target or the inspection target It was necessary to arrange in the vicinity. As a result, in addition to the standing wave of the sound wave inside the hood, a standing wave of the sound wave was also generated between the object to be inspected and the inner wall of the hood, making it more difficult to accurately measure the impact sound. Also, in a limited space such as in a tunnel, the hood opening should be in close contact with the inspection object, or placed near the inspection object to perform a hammering inspection. It can be difficult and possibly cause defects in the detection of defects.

  In view of the above circumstances, the present invention provides a hammering inspection system in which the accuracy of detecting an internal defect of an inspection target is improved by a device that selectively receives sound waves generated in response to a hit on the inspection target. For the purpose.

In order to achieve the above object, the sound inspection system of the present invention comprises:
A hitting tool that strikes the inspection target, and a hitting sound emitted from the inspection target when the inspection target is hit with this hitting tool, is collected with a microphone surrounded by a hood, and the hit obtained by this sound collection In a hammering inspection system configured with a defect detection device that detects a defect of the inspection object based on a sound signal,
The hood has an inner space having at least an opening-side sound reflection inner wall having an opening at the front end and a focal point behind the opening, and the opening side in the sound reflection inner wall. Is a sound absorbing material arranged on the opposite side,
The sound receiving surface of the microphone is located in the sound reflection inner wall and is disposed so as to face the opening.

  In the sound-inspecting system of the present invention, the sound absorbing material is disposed on the side opposite to the opening side of the hood of the sound collector. Thus, conventionally, sound is received by the microphone after being reflected within the sound reflection inner wall of the hood. Since the sound wave that has been absorbed is absorbed by the sound absorbing material, interference between the sound waves generated in the conventional sound collector is less likely to occur. Therefore, according to the hammering inspection system of the present invention, it is possible to improve the detection accuracy of the internal defect to be inspected.

  Since the microphone surrounded by the hood of the present invention can have an appropriate directivity, for example, as in the example of Non-Patent Document 1, in order to avoid the influence of ambient acoustic noise and the like as much as possible, the opening of the hood There is no need to make the part in close contact with the inspection object or to arrange it near the inspection object. Therefore, since the distance between the microphone surrounded by the hood and the inspection object can be arbitrarily set in the present embodiment, the workability of the hammering inspection can be improved. The ability to secure the distance between the microphone surrounded by the hood and the inspection object naturally contributes to the reduction of the generation of standing waves of sound waves between the inspection object and the inner wall of the hood.

  Here, it is preferable that the hood further has a sound absorbing material disposed along the peripheral edge of the opening.

  In this way, when the sound absorbing material is arranged along the peripheral edge of the opening, the sound wave that has arrived from the side or rear of the hood and is diffracted by the edge of the opening of the hood and entering the hood is attenuated. can do.

  In addition, the hood may include a light beam emitting unit that emits a light beam parallel to a rotation axis of a rotation surface shape of the sound reflection inner wall that indicates a target hitting point on the inspection target. This is a preferred embodiment.

  In this way, by hitting while pointing the desired hitting point with this light beam, the opening of the hood can be directly opposed to the hitting point, so that it is possible to accurately collect the hitting sound. . Thereby, the detection accuracy of the internal defect to be inspected can be further improved.

Furthermore, the hitting tool includes a light beam receiving unit that receives the light beam emitted from the light beam emitting unit,
Acquired by the defect detection device by a light reception result signal acquisition unit that acquires a light reception result signal representing a light reception result received by the light beam receiver, and by the light reception result signal acquisition unit corresponding to the hit on the inspection target It is also a preferred aspect that the apparatus includes a determination unit that determines whether or not the hitting is accurately performed on the hitting point indicated by the light beam based on the received light reception result signal.

  In this way, for example, when it is determined that the hitting is not exactly hitting the location pointed to by the light beam, it is possible to prompt the re-blow by issuing a warning. The accuracy can be further improved.

  Here, the defect detection device includes a distance measuring means for detecting a distance between a sound receiving surface of the microphone and a hitting point on the inspection target hit by the hitting tool, and a sound collection by the microphone. It is preferable to include correction means for correcting the obtained hitting sound signal according to the distance detected by the distance measuring means.

  In this way, even if the collected sound is performed in a state where the distance between the strike point and the microphone receiving surface is changed every time the strike is performed, the detection accuracy of the internal defect to be inspected is further increased. Improvements can be made.

Furthermore, the said impact tool is provided with the impact signal output part which outputs the impact signal according to the impact,
The ranging means obtains an impact signal output from the impact signal output unit, the timing at which the impact signal is acquired by the impact signal acquisition unit, and the impact sound signal at the microphone. A time measuring unit for measuring a time difference between the timing and the timing, and based on the time difference measured by the time measuring unit, the sound receiving surface of the microphone and the inspection object hit by the hitting tool It is also a preferable aspect that the distance between the striking surface and the surface is detected.

  Thus, between the sound receiving surface of the microphone and the hit point on the inspection object hit by the hitting tool based on the time difference from the timing at which the hit was made to the timing at which the hit sound reaches the microphone. The distance may be measured.

  The hitting tool may be an impulse hammer that outputs a force signal representing a force applied when hitting the inspection target as the hit signal.

  In this way, when the hitting tool is an impulse hammer, in addition to the timing at which the hit was made, it is possible to obtain the force information of the hit, so for example, when the force is outside a predetermined range By promoting re-blow, the detection accuracy of the internal defect to be inspected can be further improved.

  Alternatively, the ranging means emits a modulated light beam that emits a modulated light beam, and the modulated light beam emitted from the modulated light beam emitter and reflected by the inspection object and returned. The hood is provided with a modulated light beam receiving part for receiving a light beam, and the modulated light beam emitted from the modulated light beam emitting part and reflected from the timing emitted from the modulated light beam emitting part is modulated. A second time measuring unit for measuring a time difference from the timing received by the light beam receiving unit, and based on the time difference measured by the second time measuring unit, It is preferable to detect the distance between the sound receiving surface and the striking surface on the inspection object that is struck by the striking tool.

  Thus, the sound receiving surface of the microphone based on the time difference from the timing at which the modulated light beam is emitted to the timing at which the modulated light beam is reflected back to the inspection target, and the hitting point on the inspection target hit by the hitting tool The distance between the two may be measured.

  Furthermore, it is also preferable that the modulated light beam emitting unit emits a modulated light beam that indicates a target hitting point on the inspection object and that is parallel to the rotation axis of the rotation surface shape of the sound reflection inner wall. It is.

  In this way, it is possible to accurately collect the hitting sound by hitting the hitting point indicated by the modulated light beam, so that the detection accuracy of the internal defect to be inspected can be further improved. it can.

Alternatively, a modulation light beam emitting unit that emits a modulated light beam parallel to the rotation axis of the rotation surface shape of the sound reflection inner wall, which indicates the target hitting point on the inspection object, is provided in the hood. Prepared,
The hitting tool includes a modulated light beam receiving unit that receives the modulated light beam emitted from the modulated light beam emitting unit,
The distance measuring unit further receives a light reception result signal indicating a light reception result received by the modulated light beam light receiving unit, and a timing at which the modulated light beam is emitted from the modulated light beam emitting unit. And a third time measuring unit that measures a time difference between the timing at which the emitted modulated light beam is received by the modulated light beam receiving unit,
The distance measuring means calculates a distance between the sound receiving surface of the microphone and the striking surface on the inspection object hit by the striking tool based on the time difference measured by the third time measuring unit. It is preferable to detect.

  In this way, based on the time difference from the timing when the modulated light beam is emitted to the timing when it reaches the impact tool, between the sound receiving surface of the microphone and the impact point on the inspection object impacted by the impact tool The distance may be measured.

  Further, based on the light reception result signal acquired by the light reception signal acquisition unit corresponding to the hit on the inspection object, the defect detection device is accurate with respect to the hit point indicated by the light beam. It is also a preferable aspect that a determination unit for determining whether or not the operation has been performed is provided.

  In this case, for example, when it is determined that the hitting position indicated by the modulated light beam is not hitting correctly, it is possible to prompt a re-hit by performing a warning. Defect detection accuracy can be further improved.

  According to the hammering inspection system of the present invention, it is possible to improve the detection accuracy of internal defects by a device that selectively receives sound waves generated in response to a hit on an inspection target.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a configuration diagram of a first embodiment of a sound inspection system according to the present invention.

  A hammering inspection system 1 according to the present embodiment shown in FIG. 1 includes an impulse hammer 10 and a defect detection device 20, and the defect detection device 20 includes a sound collector 23 that collects the hammering sound, A repeater 22 that collects various signals and converts them into digital signals and the like, and a personal computer 21 that analyzes various signals from the repeater 22 (hereinafter, this personal computer is referred to as a personal computer). .

  The impulse hammer 10 includes a handle 10b, a striking unit 10a, a first laser beam receiving unit 10c that transmits a received laser beam to the repeater 22, a force output unit 10d that outputs a voltage signal corresponding to the striking force, and a force The first signal line 10e for transmitting the voltage signal output from the output unit 10d and the first optical fiber line 10f for transmitting the laser beam received by the laser beam receiving unit 10c.

  The sound collector 23 includes a microphone 23c that collects a hitting sound generated by hitting an inspection target by the impulse hammer 10, a sound collecting hood 23e for preventing ambient sounds from being picked up by the microphone, and the sound collecting hood. A handle 23d attached to the outside of 23e, a laser beam emitting unit 23b for emitting a laser beam, glass wool 23a as a sound absorbing material arranged around the microphone 23c, and a sounding signal output from the microphone 23c are relayed. It consists of a second signal line 23 g for transmitting to the device 22. The laser beam emitting unit 23b includes a laser diode, a beam output control unit that changes the beam output by changing the current applied to the laser diode, and the laser beam emitted from the laser diode as the hood opening direction. Also shown in FIG. 1 is a second optical fiber line 23f that is composed of a beam splitter that distributes to the repeater 22, and transmits one laser beam emitted from the laser diode and divided by the beam splitter to the repeater 22. It is a component of the sound collector 23.

  The repeater 22 is connected to the first signal line 10 e and the first optical fiber line 10 f from the impulse hammer 10, and the second signal line 23 g and the second optical fiber line 23 f from the sound collector 23. Laser beams transmitted from the optical fiber line 10f and the second optical fiber line 23f are caused to interfere with each other, and various signals are digitally converted and transmitted to the personal computer 21 through the third signal line 2a.

  The personal computer 21 corrects various digital signals transmitted from the repeater 22 and displays various digital signal waveforms on the display screen.

  FIG. 2 is an internal block diagram of the sound inspection system according to the present embodiment.

  FIG. 2 shows an internal block of the sound collector 23 on the left side, an internal block of the personal computer 21 on the center upper side, an internal block of the repeater 22 on the lower center side, and an internal block of the impulse hammer 10 on the right side.

  The impulse hammer 10 shown on the right side of FIG. 2 includes a force signal output unit 10d and a laser beam receiving unit that receives the laser beam emitted from the laser beam emitting unit 23b of the sound collector 23 and transmits the laser beam to the repeater 22. 10c.

  The sound collector 23 shown on the left side of FIG. 2 includes a microphone 23c that collects sound and outputs a sound signal, and a laser beam emitting unit 23b.

  The repeater 22 shown in the lower center of FIG. 2 includes a sound signal acquisition unit 22b that acquires a sound signal from the microphone 23c, a laser beam transmitted from the laser beam emitting unit 23b, and a laser beam transmitted from the laser beam receiving unit 10c. A laser beam interference unit 22a that causes interference with the beam, a beam output measurement unit 22d that measures the output of the laser beam from the laser beam receiving unit 10c, and a force signal acquisition unit 22c that acquires a force signal from the impulse hammer 10 It consists of

  The personal computer 21 shown in the upper center of FIG. 2 strikes the microphone 23c based on the interference result detected by the laser beam interference unit 22a of the repeater 22 and the timing at which the force signal is obtained by the force signal acquisition unit 22c. The distance calculation unit 21a that calculates the distance to the point, the timing at which the force signal is obtained by the force signal acquisition unit 22c, the output of the force signal, and the output of the laser beam obtained at the time of the impact Based on the hit judgment, it is judged whether or not the hit is accurately performed on the hit point indicated by the laser beam, or whether or not the applied force at the hit is within a predetermined range. The sound signal analysis / correction unit analyzes the sound signal by correcting the sound signal from the sound signal acquisition unit 22b of the unit 21c and the repeater 22 based on the distance information from the distance calculation unit 21a. In 21b It has been made.

  Hereinafter, the case where the internal sound detection of the inspection object 100 shown in FIG.

  Here, FIG. 3 is a frequency characteristic diagram based on the sound output signal output from the microphone arranged in the sound collection hood of the sound collector of the present embodiment.

  FIG. 3 shows the measurement of the frequency characteristics of the sound collector with respect to impact. Here, the relative sensitivity is expressed with reference to a measurement condenser microphone whose frequency characteristics are calibrated flat.

  As shown in FIG. 3, in the sound collector in which the sound absorbing material is not arranged on the back side of the sound collecting hood 23e. The sensitivity exhibits a peak in the frequency band of approximately 2 to 6 kHz due to the influence of the reflection of the sound wave in the sound collecting hood, while the sensitivity is decreased in the frequency band of approximately 11 to 15 kHz. On the other hand, the sound collector 23 in which the sound absorbing material 23a is disposed on the back side of the sound collecting hood 23e has a flat characteristic over the entire measurement frequency. Thereby, in the sound-inspection-inspection system 1 which is this embodiment, since the sound-absorbing material 23a is arrange | positioned in the back | inner side of the sound-collecting hood 23e of the sound collector 23, compared with the case where the sound-absorbing material 23a is not arrange | positioned. It can be seen that it is possible to collect sounds closer to the dial tone. This is because the sound absorbing material 23a is provided on the back side in the sound collecting hood, and in the past, the sound waves collected by the microphone after being reflected in the sound collecting hood are absorbed by the sound absorbing material. This is because interference with sound waves collected directly by the macrophone without being reflected in the sound collecting hood is less likely to occur.

  The sound collecting hood 23e of the sound collecting device 23 of the sound hitting inspection system 1 is provided with a laser beam emitting portion 23b and a microphone 23c on the back side of the center, and the above-mentioned between the inner wall of the sound collecting hood 23e. A sound absorbing material 23a is attached.

  In order to start the inspection of the inspection object 100 shown in FIG. 1, the power source of the sound inspection system 1 is turned on, and further, a laser beam emission button (not shown) provided in the sound collector 23 is turned on. Then, the laser beam 110 is emitted from the laser beam emitting unit 23b along the rotation axis of the sound collecting hood 23e having the rotating surface shape.

  As described above, the beam output of the laser beam 110 is constantly changed by the output control unit. This is the same phase as the laser beam emitted from the laser beam emitting unit 23b and transmitted to the repeater 22, and the laser beam transmitted to the repeater 22, and from the laser beam emitting unit 23b, When the phase difference between the laser beam emitted from the opening toward the inspection object, that is, the laser beam received by the impulse hammer 10, becomes an integral multiple of the wavelength, it becomes impossible to measure the distance between the microphone 23c and the hitting point. This is to prevent falling.

  Further, since the laser beam 110 is emitted along the rotation axis of the sound collecting hood 23e having the rotating surface shape, the laser beam 110 is irradiated to a desired hitting point, and the irradiated portion is hit. Thus, the hitting sound is accurately collected by the sound collector 23.

  FIG. 4 is a diagram illustrating how the sound collection characteristics of the microphone according to the present embodiment change depending on the angle of the sound source direction with respect to the rotation axis of the sound collection hood having a rotating surface shape.

  4 (a) to 4 (c) show the frequencies when the angles of the sound source direction with respect to the rotation axis of the sound collecting hood 23e having a rotating surface shape are 0 degrees, 6 degrees, and 12 degrees, respectively. The relative sensitivity for each is shown. Here, in the frequency range from 0 kHz to 16 kHz, the relative sensitivity changes between 2 and 7 in FIG. 4A, whereas in FIG. 4 and FIG. 4C shows the relative sensitivity changing between 0.5 and 2.5. The direction of the sound source with respect to the rotation axis of the sound collecting hood As the angle increases, the sensitivity to high frequencies decreases.

  In the percussion inspection system 1, the inspection target is hit while moving the sound collector 23 so as to irradiate the laser beam 110 to the hit position on the inspection target for which the order of hitting is determined in advance. The impulse hammer 10 transmits a force signal corresponding to the striking force to the repeater 21 each time a striking is performed. Further, in the sound collector 23, the hitting sound generated by hitting the inspection object by the impulse hammer 10 is collected by the microphone 23 c, and a hitting signal corresponding to the hitting sound is transmitted to the repeater 22. Yes.

  FIG. 5 is a diagram showing the applied signal output from the impulse hammer by the impact hammer and the lower part of the impact signal collected by the microphone by the impulse hammer.

  FIG. 5 shows a state in which the hitting signal shown in the lower part is detected behind the applied signal shown in the upper part, and the delay of the hitting signal with respect to the applied signal shown in FIG. The distance varies depending on the distance between the inspection target and the microphone.

  The impulse hammer 10 is provided with a laser beam receiving unit 10c that transmits a received laser beam to the repeater 22 in addition to the function of outputting a force signal according to the striking force. By hitting a hitting point, the laser beam 110 is received by the laser beam receiving unit 10c. The laser beam 110 received by the laser beam receiving unit 10c is transmitted to the repeater 22 through the first optical fiber line 10f. As described above, the laser beam 110 emitted from the sound collector 23 to the inspection object 100 is one of the two divided laser beams emitted from the laser diode, and the other is the second optical fiber line 23f. In the repeater 22, the laser beam transmitted from the sound collector 23 interferes with the laser beam transmitted from the impulse hammer 10, and the result is detected. This detection result is used for correcting the sound signal as indicating the distance between the microphone 23c and the hitting point on the inspection object 100 when the hit is made. This correction is performed in a state where the distance between the microphone 23c and the hitting point on the inspection target 100 is changed every time the sound collection is performed, so that the detection accuracy of the internal defect of the inspection target 100 is lowered. It is done to prevent

  Here, FIG. 6 is a diagram illustrating how the sound collection characteristics of the microphone of the sound-inspecting system according to the present embodiment change according to the distance from the hitting point on the inspection target.

  FIG. 6 shows the sound collection characteristics of the sound collector when the distance between the microphone 23c and the hitting point on the inspection object 100 is 50 cm, 100 cm, and 150 cm, respectively. Here, it is shown that even if the distance between the microphone 23c and the hitting point on the inspection object 100 changes between 100 cm and 150 cm, the sensitivity changes but the characteristics with respect to the frequency hardly change. Even if the distance between the microphone 23c and the hitting point on the inspection object 100 changes between 100 cm and 150 cm for each hit, if the distance between them when the hit is made is obtained It can be read from FIG. 6 that correction is possible. Note that, at a distance of 50 cm, not only sensitivity but also frequency characteristics change, but if the distance is known, correction is possible.

  Further, in the sound inspection system 1, the impact determination unit 21c determines whether or not the applied force of the impulse hammer 10 when the impact on the inspection target is performed is within a predetermined range. When the beam output measuring unit 22d detects the beam output of the laser beam received by the laser beam receiving unit 10c when it is performed, whether or not the hit on the inspection target is accurately performed on the irradiation position of the laser beam Moreover, it is determined by the hit determination unit 21c.

  It is determined whether or not the applied force is within a predetermined range in the impact determining unit 21c. If the impact force is greatly different at each impact, the detection accuracy of the internal defect of the inspection target 100 is lowered. It is also for the same reason that it is determined whether or not the striking is performed accurately with respect to the irradiation position of the laser beam. In this sound hitting system 1, when it is determined that the applied force is not within a predetermined range, or when it is determined that the striking has not been accurately performed on the irradiation position of the laser beam, the personal computer 21 is provided. A buzzer sound is generated from a speaker that is in this case, and in this case, all data obtained with the hitting is not recorded. Therefore, the user can perform re-hitting at the hitting point.

  In the personal computer 21, the detection of the distance between the hitting point and the microphone is transmitted from the result of interference transmitted from the laser beam interference unit 22a of the repeater 22 and the force signal acquisition unit 22c of the repeater 22. Based on the force signal, it is performed by the distance calculation unit 21a for each hit, and the sounding signal transmitted from the sounding signal acquisition unit 22b of the repeater 22 according to the calculation result of the distance calculation unit 21a. Correction has been made.

  In addition, the personal computer 21 displays an image of the analysis result of the blow performed on the inspection object 100, and the user can determine the presence or absence of defects inside the inspection object while viewing the display. .

  As described above, the sound-inspecting system 1 of the present embodiment includes the sound collector 23 to which the sound absorbing material is attached on the back side in the sound collecting hood. It is possible to detect a defect to be inspected with high accuracy as compared with a hammering inspection system provided with a sound collector that is not attached. Further, in this sound hit inspection system 1, for each hit, the distance between the microphone where the hit sound is collected and the hit point is measured, and the correction according to the measured distance is performed on the hit sound signal. Therefore, even if the sound collection is performed in a state where the distance between the microphone and the hitting point is changed every time the hit is made, the defect detection inside the inspection target can be performed with high accuracy. Further, in this sound inspection system 1, whether or not the applied force is within a predetermined range based on the applied signal detected for each impact, and the laser beam emitted from the laser beam emitting unit 23b of the sound collector 23. It is determined whether or not the striking position pointed to by is being hit, and if any of these is determined to be problematic, a buzzer warning is issued. The obtained data is not recorded. That is, the factor that reduces the accuracy of defect detection inside the inspection object is omitted. In the present embodiment, whether or not the applied force at the time of hitting is within a predetermined range, or the hitting point indicated by the laser beam emitted from the laser beam emitting unit 23b of the sound collector 23 is accurate. However, even if this determination is not made, the effect of the present invention is not diminished, and the sound of each hit is not reduced. The same applies even if the distance between the microphone where the sound is collected and the hitting point is not measured. In addition, if the laser beam is not used for measuring the distance between the microphone where the sound is collected and the hitting point as described above, the laser beam is not modulated to indicate the hitting point. May be used only as a thing, and even if it does not radiate | emit a laser beam from the sound collector 23, as long as the sound-absorbing material is arrange | positioned in the sound collection sound collection hood, Good.

  FIG. 7 is a diagram showing a second embodiment of the sound hitting inspection system of the present invention. In this figure, the same reference numerals as those in FIG. 1 are attached to the same types as those provided in the first embodiment and those provided in the first embodiment. .

  7 is configured by an impulse hammer 10 and a defect detection device 200. The defect detection device 200 includes a sound collector 231 for collecting sound and various kinds of sounds. A repeater 221 for collecting signals and a personal computer 211 for analyzing various signals from the repeater 221 are configured. The only difference between the present embodiment and the first embodiment is that the method of detecting the distance between the microphone and the hitting point is different for each hit. In the first embodiment, the sound collector is different. In this embodiment, the distance between the modulated laser beam emitted from the beam and the modulated laser beam emitted at the hitting point after being emitted to the inspection object side in the same phase as this is detected. Then, distance detection is performed based on the time difference between the timing of hitting by the impulse hammer 10 and the timing at which the hitting sound generated by the hitting is collected by the microphone.

  Since the impulse hammer 10 has the same type and function as the impulse hammer of the first embodiment, a description thereof will be omitted.

  The sound collector 231 includes a microphone 23c that collects a hitting sound generated by hitting an inspection target by the impulse hammer 10, a sound collecting hood 23e for preventing ambient sounds from being collected by the microphone, and a sound collecting hood of the sound collecting hood. A handle 23d attached to the outer surface, a laser beam emitting unit 231b that emits a laser beam, glass wool 23a that is a sound absorbing material for selectively collecting sound by the microphone 23c, and a sound signal are relayed from the microphone 23c. It comprises a second signal line 23g for transmitting to the device 22. Note that, unlike the laser beam emitting unit 23b of the first embodiment, the laser beam emitting unit 231b includes only a laser diode. In this embodiment, the change in the current applied to the laser diode as in the first embodiment. In addition, the laser beam emitted from the laser diode is not distributed.

  The repeater 221 is connected to the first signal line 10 e and the first optical fiber line 10 f from the impulse hammer 10 and the second signal line 23 g from the sound collector 231.

  The personal computer 211 corrects various digital signals transmitted from the repeater 221 and displays them on the display screen.

  FIG. 8 is an internal block diagram of the hammering inspection system of the present embodiment.

  FIG. 8 shows an internal block of the sound collector 231 on the left side, an internal block of the personal computer 211 on the upper center side, an internal block of the repeater 221 on the lower center side, and an internal block of the impulse hammer 10 on the right side.

  The impulse hammer 10 shown in FIG. 8 includes a force signal output unit 10d and a laser beam light receiving unit 10c that transmits the received laser beam to the repeater 221.

  The sound collector 231 shown in FIG. 8 includes a microphone 23c that collects sound and outputs a sound signal and a laser beam emitting unit 231b.

  The repeater 221 shown in FIG. 8 includes a sound signal acquisition unit 22b that acquires a sound signal from the microphone 23c, a beam output measurement unit 22d that measures the output of the laser beam from the laser beam light receiving unit 10c, and an impulse hammer. 10 includes a force signal acquisition unit 22 c that acquires a force signal from 10.

  The personal computer 211 shown in FIG. 8 strikes based on the acquisition timing of the force signal from the force signal acquisition unit 22c of the repeater 221 and the acquisition timing of the hitting signal from the hitting signal acquisition unit 22b of the repeater 221. The distance calculation unit 211a that calculates the distance between each hitting point and the microphone, the timing at which the force signal is obtained from the force signal acquisition unit 22c, and the output of the laser beam obtained at the time of the hit Based on the hit determination unit, it is determined whether or not the hit is accurately performed on the hit point indicated by the laser beam, or whether or not the force applied at the hit is within a predetermined range. 21c and the sound signal analysis / correction unit 2 that analyzes the sound signal by correcting the sound signal from the sound signal acquisition unit 22b of the repeater 22 based on the distance information from the distance calculation unit 211a. It is composed of a 1b.

  Hereinafter, the case where the internal sound detection of the inspection object 100 shown in FIG.

  When the power of the sound inspection system 2 is turned on in order to start the inspection of the inspection object and the laser beam emission button provided in the sound collector 231 is further turned on, the laser beam 111 is rotated. The light is emitted from the laser beam emitting portion 231b along the rotation axis of the sound collecting hood 23e having a surface shape. As described above, the laser beam 111 is a laser beam whose output is not controlled. However, as in the first embodiment, the laser beam 111 follows the rotation axis of the sound collection hood 23e having the rotation surface shape. Since the laser beam 111 is irradiated to a desired hitting position, the hitting sound generated by hitting the hitting position is accurately collected by the sound collector 231.

  Also in the sound inspection system 2, the test object is hit while moving the sound collector 231 so as to irradiate the laser beam 111 to the hit position on the test object for which the order of hitting is determined in advance. The hammer 10 transmits a force signal corresponding to the striking force to the repeater 211 each time a striking is performed. Further, from the sound collector 231, the hitting sound generated by hitting the inspection object by the impulse hammer 10 is collected by the microphone 23 c and the hitting signal is transmitted to the repeater 221.

  The impulse hammer 10 is provided with a laser beam receiving unit 10c that transmits a received laser beam to the repeater 22 in addition to the function of outputting a force signal corresponding to the striking force. By striking the striking point where the emitted laser beam is irradiated, the laser beam is received by the laser beam receiving unit 10c. The laser beam received by the laser beam receiving unit 10c is transmitted to the repeater 221 through the first optical fiber line 10f.

  Further, in the sound inspection system 2, the impact determination unit 21c determines whether or not the applied force of the impulse hammer 10 when the impact on the inspection target is performed is within a predetermined range. Since the beam output of the laser beam received by the laser beam receiving unit 10c at the time of the detection is detected by the beam output measuring unit 22d, the test object is accurately hit with respect to the irradiation position of the laser beam. Whether or not the hit determination unit 21c also determines whether or not the hit has occurred.

  Even in this sound hitting inspection system 2, if it is determined that the applied force is not within the predetermined range, or if it is determined that the striking has not been accurately performed on the irradiation position of the laser beam, the personal computer 21 is equipped. A buzzer sound is generated from the speaker.

  In the personal computer 211, the detection of the distance between the hitting point and the microphone is based on the timing of transmission of the sound signal from the sound signal acquisition unit 22b of the repeater 221 and the force signal acquisition unit 22c of the repeater 221. Based on the time difference from the transmission timing of the force signal, the distance calculation unit 211a performs each hit, and according to the calculation result of the distance calculation unit 211a, from the sound signal acquisition unit 22b of the repeater 221. The transmitted sound signal is corrected.

  Further, the personal computer 211 displays an image of the analysis result of the hit made on the inspection object 100, and the user can determine whether there is a defect inside the inspection object.

  As described above, the sound-inspecting system 2 of the present embodiment also includes the sound collector 231 provided with the sound absorbing material on the back side in the sound collecting hood, so that the sound absorbing material is provided in the sound collecting hood. Compared with a not-performed sound inspection system, it is possible to detect a defect to be inspected with high accuracy. In addition, in this percussion inspection system 2, the detection of the distance between the percussion sound collecting microphone and the percussion point for each impact is based on the percussion signal from the percussion signal acquisition unit 22b of the repeater 221. Based on the time difference between the transmission timing and the transmission timing of the force signal from the force signal acquisition unit 22c of the repeater 221, this is performed by the distance calculation unit 211a, and according to the distance detected here. Since the correction is performed on the sound signal, even if the sound collection by the microphone is performed with the distance between the microphone and the hitting point being changed at each impact, the defect detection inside the inspection object is detected. Can be performed with high accuracy. Further, also in this sound inspection system 2, whether or not the applied force is within a predetermined range based on the applied signal detected for each impact, and the laser beam emitted from the laser beam emitting unit 231b of the sound collector 231. It is determined whether or not the striking position pointed to by is accurately hit, and if any of these is judged to be problematic, a buzzer warning is issued. A reduction in accuracy of defect detection inside the object is prevented. Even in this embodiment, whether or not the applied force at the time of hitting is within a predetermined range, or the hit position indicated by the laser beam emitted from the laser beam emitting unit 231b of the sound collector 231 is hit. However, the effect of the present invention is not diminished even if this determination is not performed, and the sound collection of the hit sound is performed for each hit. The same applies to the case where the distance between the microphone and the hitting point where measurement is performed is not measured. Even if the laser beam is not emitted from the sound collector 231, it may be anything as long as the sound absorbing material is disposed in the sound collecting hood.

  FIG. 9 is a diagram showing a third embodiment of the sound inspection system of the present invention. In this figure, the same reference numerals as those in FIG. 1 are attached to the same types as those provided in the first embodiment and those provided in the first embodiment. .

  The hammering inspection system 3 according to the present embodiment shown in FIG. 9 includes an impulse hammer 10 and a defect detection device 210. The defect detection device 210 includes a sound collector 232 that collects a hammering sound, and various types. A repeater 222 that collects signals and a personal computer 21 that analyzes various signals from the repeater 222 are configured. The only difference between the present embodiment and the first embodiment is that the method of detecting the distance between the microphone and the hitting point is different for each hit. In the present embodiment, the sound collector 232 is different. The distance is detected by causing the modulated laser beam emitted from the laser beam to interfere with the modulated laser beam reflected by the inspection object and returned to the sound collector 232.

  Since the impulse hammer 10 has the same type and function as the impulse hammer of the first embodiment, a description thereof will be omitted.

  The sound collector 232 includes a microphone 23c that collects a hit sound generated by striking an inspection object with an impulse hammer, a sound collecting hood 23e for preventing sound from the surroundings from being collected by the microphone, and a sound collecting hood of the sound collecting hood. A handle 23d attached to the outer surface, a laser beam emitting portion 23b for emitting a laser beam, glass wool 23a as a sound absorbing material for selectively collecting sound by the microphone 23c, and a microphone 23c to the repeater 222 It is composed of a second signal line 23g for transmitting the hitting signal. The laser beam emitting unit 23b includes a laser diode, a beam output control unit that changes the beam output by changing the current applied to the laser diode, and a laser beam emitted from the laser diode. A second optical fiber line 23f for transmitting one of the laser beams emitted from the laser diode and split by the beam splitter to the repeater 222. The second laser beam receiving unit 232b that receives the other laser beam emitted from the laser diode divided by the beam splitter and reflected back from the inspection target, and the second laser beam receiving unit 232b received the laser beam. A third optical fiber for transmitting the laser beam to the repeater 222 Even lines 23h has a component of the sound collector 232 illustrated in FIG.

  The repeater 222 includes the first signal line 10e and the first optical fiber line 10f from the impulse hammer 10, the second signal line 23g, the second optical fiber line 23f, and the third optical fiber line from the sound collector 232. 23h is connected to cause the laser beams transmitted from the second optical fiber line 23f and the third optical fiber line 23h to interfere with each other, and various signals are digitally converted and transmitted to the personal computer 21 through the third signal line 2a.

  The personal computer 21 corrects various digital signals transmitted from the repeater 222 and displays them on the display screen.

  FIG. 10 is an internal block diagram of the sound inspection system according to the present embodiment.

  FIG. 10 shows an internal block of the sound collector 232 on the left side, an internal block of the personal computer 21 on the upper center side, an internal block of the repeater 222 on the lower center side, and an internal block of the impulse hammer 10 on the right side.

  The impulse hammer 10 shown in FIG. 10 includes a force signal output unit 10d and a first laser beam receiving unit 10c for transmitting the received laser beam to the repeater 222.

  The sound collector 232 shown in FIG. 10 includes a microphone 23c that collects a hitting sound and outputs a hitting signal, a laser beam emitting unit 23b, and a second laser beam receiving unit 232b.

  The repeater 222 shown in FIG. 10 interferes with the sound signal acquisition unit 22b that acquires the sound signal from the microphone 23c, the laser beam from the laser beam emission unit 23b, and the laser beam from the second laser beam receiving unit 232b. A laser beam interfering unit 22a to perform, a beam output measuring unit 22d for measuring the output of the laser beam from the first laser beam receiving unit 10c, and a force signal acquiring unit 22c for acquiring a force signal from the impulse hammer 10. Has been.

  The personal computer 21 shown in FIG. 10 obtains the timing at which the force signal is obtained from the force signal acquisition unit 22d based on the interference result detected by the laser beam interference unit 22a of the repeater 222, and at the time of the hit. Whether or not the hit was made accurately at the hit point indicated by the laser beam based on the output of the laser beam, or whether the force applied during the hit was within a predetermined range The hit determination unit 21c that determines whether or not, the hit for each hit based on the acquisition timing of the force signal from the force signal acquisition unit 22c of the repeater 222 and the interference result from the laser beam interference unit 22a of the repeater 222 The distance calculation unit 21a that calculates the distance between the point and the microphone, and the sound signal from the sound signal acquisition unit 22b of the repeater 222 are used as distance information from the distance calculation unit 21a. Is composed of a slapping sound signal analysis and correction unit 21b for analyzing hammering sound signal is corrected based.

  Hereinafter, the case where the internal sound detection of the inspection object 100 shown in FIG.

  In the sound collecting hood 23e of the sound collector 232 of the sound hitting inspection system 3 according to the present embodiment, a laser beam emitting unit 23b, a second laser beam receiving unit 232b, and a microphone 23c are arranged at the center back side, and these are collected. A sound absorbing material 23a is attached to the inner wall of the sound collecting hood.

  When the power source of the sound inspection system 3 is turned on to start the inspection of the inspection object and the laser beam emission button provided in the sound collector 232 is turned on, the laser beam 112 is rotated. The light is emitted from the laser beam emitting portion 23b along the rotational axis of the sound collecting hood having a surface shape.

  The output of the laser beam 112 is always changed by the output control unit that changes the output as described above. This is because the sound receiving surface 231c of the microphone 23c is obtained when the phase difference between the laser beam transmitted from the laser beam emitting unit 23b to the repeater 222 and the returned laser beam reflected by the inspection object becomes an integral multiple of the wavelength. This is to prevent the distance measurement between the test object and the hitting position on the inspection target from being disabled.

  In the percussion inspection system 3, the impact on the inspection target is performed while moving the sound collector 232 so that the laser beam 112 is irradiated to the impact point on the inspection target for which the order of hitting is determined in advance. The hammer 10 transmits a force signal corresponding to the striking force to the repeater 222 each time a striking is performed. Further, in the sound collector 232, as in the first embodiment, the laser beam emitted from the laser diode of the laser beam emitting unit 23b is divided, and one of them is transmitted to the repeater 222 through the second optical fiber line. In addition, the other laser beam emitted from the laser beam emitting part 23b to the outside of the sound collecting hood, reflected by the inspection object, and received by the second laser beam receiving part 232b is converted into the third optical fiber line. To the repeater 222. Further, the hitting sound generated by hitting the inspection object by the impulse hammer 10 is collected by the microphone 23c, and the hitting signal is transmitted from the microphone 23c to the repeater 222 through the second signal line 23g.

  The impulse hammer 10 is provided with a first laser beam receiving unit 10c that receives a laser beam from the sound collector 232 in addition to a function of outputting a force signal corresponding to the striking force. By hitting the indicated hitting point, the laser beam emitted from the laser beam emitting unit 23b is received by the first laser beam receiving unit 10c. The laser beam received by the first laser beam receiving unit 10c is transmitted to the repeater 222 through the first optical fiber line 13. In the present embodiment, as described above, the microphone at the time of impact is performed. The distance detection between the impact point 23c and the hitting point is performed based on the laser beam transmitted from the laser beam emitting unit 23b and the second laser beam receiving unit 232b of the sound collector 232 to the repeater 222, and this impulse. Whether the laser beam received by the first laser beam receiving unit 10c of the hammer 10 and transmitted to the repeater 222 strikes the hitting point irradiated by the laser beam emitted from the laser beam emitting unit 23b accurately. It is used only by the hit determination unit 21c that determines

  In the hammering inspection system 3, it is determined in the hit determination unit 21 c whether or not the force applied by the impulse hammer 10 when hitting an inspection target is within a predetermined range.

  In the personal computer 21, the distance detection between the hitting point and the microphone described above is transmitted from the result of interference transmitted from the laser beam interference unit 22 a of the repeater 222 and the force signal acquisition unit 22 c of the repeater 222. The sound is transmitted from the sound signal acquisition unit 22b of the repeater 222 according to the calculation result of the distance calculation unit 21a. The signal is corrected.

  Further, the personal computer 21 displays an image of the analysis result of the hit made on the inspection object 100, and the user can determine whether there is a defect inside the inspection object.

  As described above, the sound-inspecting system 3 according to the present embodiment includes the sound collector 232 in which the sound-absorbing material is arranged on the back side in the sound-collecting hood. It is possible to detect a defect to be inspected with high accuracy as compared with a hammering inspection system provided with a sound collector that is not arranged. Further, in this sound hitting inspection system 3, for each hit, the distance between the microphone where the hitting sound is collected and the hitting point is set such that the laser beam from the laser beam emitting unit 23b and the second laser beam receiving unit 232b. Since the sound signal correction is performed according to the measured distance measured by interfering with the laser beam from, the collected sound changes the distance between the microphone and the impact point at each impact. Even if it is performed in a state, it is possible to detect a defect inside the inspection object with high accuracy. Further, in the sound inspection system 3, whether or not the applied force is within a predetermined range based on the applied signal detected for each impact, and the laser beam emitted from the laser beam emitting unit 23b of the sound collector 232 It is determined whether or not the striking position pointed to by is accurately hit, and if any of these is determined to be problematic, a buzzer warning is issued. In the present embodiment, whether or not the applied force at the time of hitting is within a predetermined range, or the hitting point indicated by the laser beam emitted from the laser beam emitting unit 23b of the sound collector 232 is accurate. However, even if this determination is not made, the effect of the present invention is not diminished, and the sound of each hit is not reduced. The same applies even if the distance between the microphone where the sound is collected and the hitting point is not measured. In addition, if the laser beam is not used for measuring the distance between the microphone where the sound is collected and the hitting point as described above, the laser beam is not modulated to indicate the hitting point. It may be used only as a thing. Furthermore, even if it does not emit a laser beam from the sound collector 232, it is sufficient if a sound absorbing material is disposed in the sound collecting sound collecting hood.

  In the first to third embodiments, an example in which an impulse hammer is used as a hitting tool is described. However, the present invention is not limited to this, and a signal indicating the timing of hitting is externally provided. The output of the present invention is not limited even if it is a normal hammer as long as it can output a hitting sound from an inspection object by hitting.

  Furthermore, in the first to third embodiments, the case where the sound absorbing material is disposed around the microphone in the sound collecting hood of the sound collecting device has been described as an example, but this sound absorbing material is the opening of the sound collecting hood. By using a sound collector that is also arranged at the periphery of the hood, the sound wave that arrives from the side or rear of the hood and is diffracted by the edge of the hood opening and entering the hood is attenuated. Since the interference between sound waves can be further suppressed, the detection accuracy of the internal defect to be inspected can be further improved.

  FIG. 11 is a cross-sectional view of an example of the sound collecting hood in which the sound absorbing material is also disposed at the peripheral edge of the opening of the sound collecting hood. In addition, what is shown here and the same kind as what is used in 1st Embodiment is attached | subjected the code | symbol same as the code | symbol attached | subjected in 1st Embodiment.

  In the sound collecting hood 23e shown in FIG. 11, the glass wool 24a, which is a sound absorbing material, is arranged on the entire circumference in addition to the periphery of the microphone as described above. The glass wool 24a at the peripheral edge of the opening is not limited to the one arranged on the entire circumference as shown in FIG. 11, and may be detachable.

  In addition to this, in addition to the periphery of the microphone, glass wool is arranged at the periphery of the sound collection hood opening, and the sound waves that are diffracted at the edge of the hood opening and enter the hood are attenuated. Degradation of directivity is also suppressed.

  FIG. 12 is a graph showing the directivity characteristics of the sound collector.

  12A shows the directivity characteristics of the sound collector in which the sound absorbing material is disposed only around the microphone, and FIG. 12B shows the periphery of the opening of the sound collecting hood in addition to the microphone. In addition, the directivity characteristics of the sound collector which is an aspect of the above-described embodiment in which the sound absorbing material is disposed are shown for each frequency.

  From FIG. 12, by arranging the sound absorbing material in the periphery of the opening of the sound collecting hood in addition to the periphery of the microphone, the directivity characteristics with respect to the side and the rear of the sound collector are improved for 1 kHz. It can be seen that the improvement of the directivity with respect to the direction is remarkable, and for 10 kHz, the directivity in the direction close to the front of the sound collector is improved.

  Furthermore, by arranging the sound absorbing material also at the peripheral edge of the opening of the sound collecting hood, it is possible to reduce the impact when the opening of the sound collecting device comes into contact with the object to be inspected and to prevent the damage of both. . The sound absorbing material may be other than glass wool as long as it has sound absorbing properties. In the present embodiment, the case where the sound absorbing material is disposed outside the peripheral edge of the opening of the sound collecting hood has been described as an example, but the present invention is not limited thereto, and the sound absorbing material is disposed inside the peripheral edge. You may do.

It is a lineblock diagram of a 1st embodiment of a sound inspection system of the present invention. It is an internal block diagram of the sound inspection system of this embodiment. It is a frequency characteristic figure with respect to the hit sound of the sound collector of this embodiment. It is a figure which shows a mode that the sound collection characteristic of the microphone of this embodiment changes with the angle of the sound source direction with respect to the rotating shaft of the sound collection hood which is a rotation surface shape. FIG. 4 is a diagram illustrating an applied signal output from an impulse hammer by an impact hammer and an impact signal of a hit sound collected by a microphone by the impact hammer. It is a figure which shows a mode that the sound collection characteristic of the microphone of the sound-inspection-inspection system of this embodiment changes according to the distance from the impact point on a test object. It is a figure which shows 2nd Embodiment of the tap sound test | inspection system of this invention. It is an internal block diagram of the sound inspection system of this embodiment. It is a figure which shows 3rd Embodiment of the tapping sound inspection system of this invention. It is an internal block diagram of the sound inspection system of this embodiment. It is sectional drawing of an example of the sound collection hood by which a sound absorption material is arrange | positioned also in the peripheral part of opening of the sound collection hood. It is a graph which shows the directivity characteristic of a sound collector.

Explanation of symbols

1, 2 and 3 hammering sound inspection system 2a third signal line 10c first laser beam receiving unit 10d force output unit 10e first signal line 10f first optical fiber line 20 defect detection device 21a distance calculation unit 21b hammering signal analysis・ Correction unit 21c Impact determination unit 22 Repeater 22a Laser beam interference unit 22b Impact signal acquisition unit 22c Force signal acquisition unit 22d Beam output measurement unit 23 Sound collector 23a, 24a Glass wool 23b Laser beam emission unit 231c Sound receiving surface 23f Second optical fiber line 23g Second signal line 23h Third optical fiber line

Claims (9)

A striking tool for striking the inspection target, and a striking sound emitted from the inspection target at the time of striking the inspection target with the striking tool is collected by a microphone surrounded by a hood, and the striking obtained by the sound collection In a sound-inspecting system configured with a defect detection device that detects a defect of the inspection object based on a sound signal,
The hood has an internal space having at least a rotating surface-shaped sound reflection inner wall having an opening at a front end and a focal point behind the opening, and the opening side in the sound reflection inner wall. the der what sound absorbing material is disposed on the opposite side Rutotomoni points to blow point as a target on said object, the light beam for emitting a light beam parallel to the rotation axis of the rotating surface shape of the sound reflecting inner wall It has a light emitting part ,
The impact tool includes a light beam receiving unit that receives the light beam emitted from the light beam emitting unit,
Acquired by the defect detection device by a light reception result signal acquisition unit that acquires a light reception result signal representing a light reception result received by the light beam receiver, and by the light reception result signal acquisition unit corresponding to the hit on the inspection target A determination unit for determining whether or not the hitting is accurately performed on the hitting point indicated by the light beam based on the received light reception result signal,
The sound-inspecting system according to claim 1, wherein a sound receiving surface of the microphone is disposed so as to be located in the sound reflection inner wall and to face the opening. The sound inspection system according to claim 1, wherein a sound absorbing material is further arranged along the outer periphery of the opening. The defect detection device is obtained by sound collecting by the microphone, ranging means for detecting a distance between the sound receiving surface of the microphone and a hitting point on the inspection target hit by the hitting tool. striking sound inspection system of claim 1, wherein the kite and a correcting means for correcting the impact sound signal in response to the distance detected by said distance measuring means. The striking tool includes a striking signal output unit that outputs a striking signal corresponding to the striking ,
The ranging means obtains a batting signal acquisition unit for obtaining a batting signal output from the batting signal output unit, the timing at which the batting signal is obtained by the batting signal acquisition unit, and the batting sound signal in the microphone. A time measuring unit that measures a time difference between the sound receiving timing and the timing, and based on the time difference measured by the time measuring unit, the sound receiving surface of the microphone and the inspection object hit by the hitting tool The sound inspection system according to claim 3, wherein a distance between the hitting surface and the hitting surface is detected . 5. The sound hitting inspection system according to claim 4 , wherein the hitting tool is an impulse hammer that outputs a force signal representing a force applied when the test object is hit as the hit signal . The distance measuring means emits a modulated light beam that emits a modulated light beam, and a modulated light beam that is emitted from the modulated light beam emitter and reflected back from the inspection object And a modulated light beam receiving unit that receives the modulated light beam. The modulated light beam is emitted from the modulated light beam emitting unit and reflected from the modulated light beam emitting unit. A second time measuring unit that measures a time difference from the timing received by the light receiving unit is provided , and the microphone receives sound based on the time difference measured by the second time measuring unit. The sound inspection system according to claim 3 , wherein a distance between the surface and a striking surface on the inspection object hit by the striking tool is detected. The modulated light beam emitting unit emits a modulated light beam that indicates a target hitting point on the inspection target and is parallel to a rotation axis of a rotation surface shape of the sound reflection inner wall. Item 6. The sound inspection system according to item 6. The hood includes a modulated light beam emitting unit that emits a modulated light beam that emits a modulated light beam parallel to a rotation axis of a rotation surface shape of the sound reflection inner wall that indicates a target hitting point on the inspection target,
The impact tool includes a modulated light beam receiving unit that receives the modulated light beam emitted from the modulated light beam emitting unit,
The distance measuring unit further acquires a light reception result signal indicating a light reception result received by the modulated light beam light receiving unit, and a timing at which the modulated light beam is emitted from the modulated light beam emission unit And a third time measuring unit that measures a time difference between the timing at which the emitted modulated light beam is received by the modulated light beam receiving unit ,
The distance measuring means determines a distance between the sound receiving surface of the microphone and a striking surface on the inspection object hit by the striking tool based on the time difference measured by the third time measuring unit. The sound inspection system according to claim 3 , wherein the sound inspection system is one to detect. Based on the light reception result signal acquired by the light reception signal acquisition unit corresponding to the hit on the inspection object, the defect detection device accurately performs the hit on the hitting point indicated by the light beam. The sound inspection system according to claim 8, further comprising a determination unit that determines whether or not the sound has been received.

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