JP2020067404A - Hole inspection method and hole inspection device - Google Patents

Abstract

To remove limitations, due to a size of a microphone, on a plane size of an inspection object component and a hole formed in the inspection object component, and also enable high-precision hole inspection.SOLUTION: A hole inspection device comprises: a speaker 110 installed in a closed type enclosure 100 having an opening 102; a speaker drive part 120 which makes a frequency sweep of the speaker 110; a standard microphone 130 which outputs an electric signal depending upon a flow rate of fluid passing through a hole when the frequency sweep of the speaker 110 is made with a component having the hole placed covering the opening; a frequency analysis part 140 which performs frequency analysis of the electric signal output from the standard microphone 130 to generate a resonance frequency spectrum; and a hole inspection part 150 which determines whether the hole is proper based upon the resonance frequency spectrum. It is determined whether the hole is proper based upon the reference resonance frequency generated corresponding to a master sample and an inspection object resonance spectrum generated corresponding to the inspection object component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hole inspection method and a hole inspection device for inspecting holes formed in a component.

  As an apparatus for inspecting the suitability of a hole formed in a component, for example, a fine hole inspection apparatus and a fine hole inspection method described in Patent Document 1 (hereinafter referred to as a fine hole inspection apparatus described in Patent Document 1 Abbreviated.)

  FIG. 10 is a diagram shown for explaining the fine hole inspection apparatus 900 described in Patent Document 1. Note that FIG. 10 is a diagram showing a main part of the fine hole inspection apparatus 900 described in Patent Document 1. As shown in FIG. 10, a micropore inspection apparatus 900 described in Patent Document 1 is installed on a substantially hermetically sealed casing 910 having a space inside, and on one end face side inside the casing 910. , A speaker (not shown) that outputs a low-frequency sound by a low-frequency signal, and a microphone that outputs a predetermined electric signal by vibrating the diaphragm in response to the low-frequency sound output by the speaker (for example, dynamic Type microphone) 920 and a microphone mounting surface 930a, and a component mounting surface 930b for mounting a component 940 on a surface opposite to the microphone mounting surface 930a, and a diaphragm 921 of the microphone 920 is provided. A partition member 930 having an air passage hole 931 through which air vibration generated by the vibration is passed to the component mounting surface 930b side. , The has.

  In such a configuration, a speaker (not shown) is mounted on the component mounting surface 930b so that the micro holes 941 formed in the component 940 communicate with the air passage holes 931. By emitting a low-frequency sound, the microphone 920 outputs an electric signal that depends on the flow rate of air when the air passing through the air passage hole 931 passes through the fine hole 941. Based on the electric signal, the fine hole is output. The suitability of is checked.

Japanese Patent No. 5715516

  Since the fine hole inspection device 900 described in Patent Document 1 has the above-described configuration, the inspection target component 940 has a planar size (for example, a hole diameter) of the fine holes 941 formed in the inspection target component 940. However, the diameter needs to be smaller than the microphone 920 (smaller than the diameter of the diaphragm 921 of the microphone 920).

  In order to deal with this, it is conceivable to use a large microphone, but in the fine hole inspection apparatus 900 described in Patent Document 1, the inspection target component itself has a small size (outer diameter is several mm to several tens). Since the housing 910 is small, the size of the microphone 920 installed in the housing 910 is limited. Therefore, the fine hole inspection apparatus 900 described in Patent Document 1 is not suitable for inspecting a component having a relatively large plane size (for example, hole diameter) of holes.

  The micropore inspection apparatus 900 described in Patent Document 1 is an excellent micropore inspection apparatus that enables high-precision inspection in a short time when, for example, inspecting micropores having a hole diameter of about 100 μm. There is a problem that the planar size (for example, hole diameter) of the hole formed in the inspection target component is limited by the microphone. In particular, if the diameter of the hole formed in the component to be inspected is in mm, or in the unit of several tens of mm, or even in the unit of several tens of mm, the inspection of the hole may not be possible.

  Therefore, according to the present invention, it is possible to inspect a hole without limiting the planar size of the hole formed in the component to be inspected by the microphone, and moreover, it is possible to perform the hole inspection with high accuracy in a short time. An object is to provide a hole inspection method and a hole inspection device.

  In order to achieve the above-mentioned object, the present inventor scrutinized what kind of inspection should be performed, and as a result, helmholtz resonance is a component to be inspected (a component in which a hole for allowing fluid and light to flow is formed). ) Was applied to the inspection of the holes formed in

  Here, the Helmholtz resonance is a phenomenon in which when a container having a relatively small opening, such as an empty bottle, is blown, a "baud" sound is heard, and a container that generates such Helmholtz resonance (helmholtz resonance It was thought that the opening of the container could be replaced with the hole formed in the part to be inspected.

  FIG. 1 is a diagram illustrating Helmholtz resonance. As shown in FIG. 1, in a container 2 having an opening 1, assuming that the diameter of the opening 1 is a, the length of the opening 1 is 1, the volume of the container 2 is V, and the sound velocity is C, the resonance frequency f is

Can be expressed as In the equation (1), ls is the opening end correction amount, and here, ls = 0.85 × a / 2.

  Here, the opening 1 of the Helmholtz resonator is replaced with a component in which a hole is formed, and the thickness of the component, that is, the depth of the hole (corresponding to 1 in FIG. 1) is kept constant and the hole diameter (a in FIG. When the resonance frequency when (corresponding to a) was changed by the equation (1), it was confirmed from the calculated values that the resonance frequency changes due to the change in the pore diameter.

  Further, when the resonance frequency when the hole depth (corresponding to a in FIG. 1) is changed and the hole depth (corresponding to 1 in FIG. 1) is changed is obtained by the above formula (1), the It was confirmed in the calculated values that the resonance frequency changes with the depth change.

  Therefore, as a result of various tests, the present inventor confirmed that Helmholtz resonance can be applied to inspection of holes in a component to be inspected (a component in which a hole for allowing fluid to flow) is applied, and the present invention It came to completion.

  [1] That is, the hole inspection method of the present invention is a hole inspection method for inspecting holes that are formed in a component to be inspected and through which a fluid or light can pass, and that has a space inside and one surface. A housing having an opening and a portion other than the opening being sealed, and a surface of the space formed in the housing opposite to a surface having the opening are provided, and sound is directed toward the opening. A speaker that outputs a frequency, a speaker driving unit that sweeps a frequency within a predetermined range within a predetermined time with respect to the speaker, and a component that is installed at a predetermined position in the space and that has the hole covers the opening. A microphone that outputs an electric signal depending on the flow rate of gas passing through the hole when the speaker drive section sweeps the frequency of the speaker in a mounted state, and is output from the microphone. A frequency analysis unit that performs a frequency analysis on the air signal to generate a resonance frequency spectrum in which a resonance frequency exists, and a hole inspection unit that inspects the size of the hole based on the resonance frequency spectrum generated by the frequency analysis unit. And a master sample having a hole formed therein, which has been confirmed to be capable of passing a predetermined amount of fluid or light, and a hole having a size different from the size of the hole formed in the master sample. A plurality of samples formed and confirmed to be capable of passing a predetermined amount of fluid or light are used, and for each sample including the master sample and the plurality of samples, the casing is sequentially In a state where the speaker is placed so as to cover the opening of the body, the step of frequency sweeping the speaker and the frequency of the electric signal output from the microphone are divided. And generating a resonance frequency spectrum for each sample, and obtaining a correlation between a spectral component contained in the resonance frequency spectrum for each sample and the size of the hole formed in each sample. A step of frequency sweeping the speaker in a state where the inspection target component is placed so as to cover the opening, and an electrical signal output from the microphone is frequency analyzed to perform an inspection corresponding to the inspection target component. Generating a target resonance frequency spectrum, spectral components included in the inspection target resonance frequency spectrum, "spectral components included in the resonance frequency spectrum of each of the samples, and holes formed in the samples. Based on the "correlation with the size of the Performing a size check.

  As described above, since the hole inspection method of the present invention uses the Helmholtz resonance to inspect the size of the hole formed in the inspection target component, the flat surface of the hole formed in the inspection target component The hole size can be inspected without being limited by the microphone, and the hole size can be inspected with high accuracy in a short time. Note that the holes formed in the inspection coping component are holes through which fluid or light can pass, but are mainly holes that allow passage of fluid.

  [2] In the hole inspection method of the present invention, the electric signal output from the microphone is a sine wave signal, and the frequency analysis unit performs a fast Fourier transform on the sine wave signal to obtain each of the samples. It is preferable to generate a resonance frequency spectrum and the resonance frequency spectrum to be inspected.

  Thereby, the resonance frequency spectrum and the inspection target resonance frequency spectrum for each sample can be generated from the sine wave signal output from the microphone.

  [3] In the hole inspection method of the present invention, the master sample is a sample for determining suitability of the size of the hole formed in the inspection target component, and the step of inspecting the size of the hole includes Of the resonance frequency spectrum of each sample, based on a spectrum component included in the resonance frequency spectrum of the master sample and a spectrum component included in the resonance frequency spectrum of the inspection target, the inspection target component is formed. It is preferable to determine the suitability of the size of the holes.

  As described above, based on the spectral components included in the resonance frequency spectrum obtained corresponding to the master sample and the spectral components included in the inspection target resonance frequency spectrum obtained corresponding to the inspection target component, the suitability of the hole size is determined. By determining, it is possible to inspect the suitability of the hole size without limiting the planar size of the hole formed in the inspection target component by the microphone, The process of determining the suitability of the size can be performed with high accuracy in a short time. In addition, "determining the suitability of the hole formed in the inspection target component" means determining the suitability of the hole of the inspection target component with respect to the master sample.

  [4] In the hole inspection method of the present invention, the spectral component is an amplitude value, and the resonance frequency existing in the resonance frequency spectrum of the master sample is used as a reference resonance frequency, and the amplitude value of the reference resonance frequency is used as a reference. When the amplitude value, "correlation between the components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" is the resonance frequency spectrum of each sample at the reference resonance frequency. Is a correlation between the amplitude value and the size of the hole formed in each sample, the step of determining the suitability of the size of the hole, the reference amplitude value and the resonance frequency spectrum of the inspection object at the reference resonance frequency of It is preferable to determine the suitability of the size of the hole formed in the inspection target component based on the amplitude value.

  In this way, by determining the suitability of the hole formed in the inspection target component based on the reference amplitude position and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency, the inspection target component is formed in the inspection target component. Whether or not the hole is appropriate can be surely performed.

  This is because even if there is a slight difference between the resonance frequency (reference resonance frequency) existing in the resonance frequency spectrum of the master sample and the resonance frequency existing in the resonance frequency spectrum under test, it also exists in the resonance frequency spectrum of the master sample. Between the reference amplitude value and the amplitude value of the resonance frequency spectrum to be inspected at the reference resonance frequency, even if the difference between the amplitude value of the resonance frequency and the amplitude value of the resonance frequency existing in the inspection resonance frequency spectrum is small. It has been confirmed by a test that a relatively large difference occurs, and from this, based on the reference amplitude value and the amplitude value of the resonance frequency spectrum of the inspection object at the reference resonance frequency, the hole formed in the inspection object part is The suitability of the holes formed in the parts to be inspected can be reliably determined by determining the suitability of Can.

  [5] In the hole inspection method of the present invention, the reference amplitude value is set with an allowable range for determining the suitability of the size of the hole formed in the inspection target component. The step of determining the suitability of, the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency, by determining whether or not within the allowable range, of the hole formed in the inspection target component. It is preferable to judge the suitability of the size.

  With this, in the step of determining the suitability of the size of the hole, the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency is formed only in the inspection target component by only determining whether the amplitude value is within the allowable range. The suitability of the size of the hole formed can be instantly determined, and the hole formed in the inspection target component can be inspected in a short time.

  [6] In the hole inspection method of the present invention, first to nth (n is a natural number) resonance frequency spectra are generated for each sample in the frequency analysis results obtained corresponding to each sample. In this case, among the first to nth (n is a natural number) resonance frequency spectra for each sample, a large difference in amplitude value of each resonance frequency spectrum of each sample at the reference resonance frequency is obtained. It is preferable to use a resonance frequency spectrum.

  As described above, the first to nth (n is a natural number) resonance frequency spectra may be generated depending on the shape and size of the casing of the hole inspection apparatus. In such a case, each resonance frequency spectrum at the reference resonance frequency is generated. It is preferable to use a resonance frequency spectrum in which the difference in the amplitude value of each resonance frequency spectrum of the sample is large among the first to nth (n is a natural number) resonance frequency spectrum of each sample. Thereby, inspection with higher resolution can be performed. The 1st to n-th (n is a natural number) resonance frequency spectra are the 1st to n-th (n is a natural number) resonance frequency spectra in order of increasing frequency.

  [7] In the hole inspection method of the present invention, the spectral component is an amplitude value, and "the spectral component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample are The “correlation of” is a correlation between the amplitude value of each resonance frequency existing in each resonance frequency spectrum of each sample and the size of the hole formed in each sample including the master sample, and the resonance of the master sample. When the amplitude value of the resonance frequency existing in the frequency spectrum is the reference amplitude value, the step of determining the suitability of the size of the hole, the amplitude value of the resonance frequency existing in the reference amplitude value and the resonance frequency spectrum to be inspected, It is preferable to determine the suitability of the size of the hole formed in the inspection target component based on the above.

  This may cause a clear difference between the amplitude value (reference amplitude value) of the resonance frequency spectrum of the master sample and the amplitude value of the resonance frequency existing in the resonance frequency spectrum to be inspected. The suitability of the hole formed in the inspection target component can be determined based on the amplitude value of the resonance frequency spectrum of the sample and the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum. In this case, the "amplitude value of the resonance frequency existing in the inspection resonance frequency spectrum" does not mean "the amplitude value of the inspection resonance frequency spectrum at the reference resonance frequency", but the resonance existing in the inspection resonance frequency spectrum. It is the maximum value of the frequency amplitude value.

  [7] In the hole inspection method of the present invention, an allowable range for determining the suitability of the size of the hole is set to the reference amplitude value, and the step of determining the suitability of the size of the hole includes Determining the appropriateness of the size of the hole formed in the inspection target component by determining whether the amplitude value of the resonance frequency present in the inspection target resonance frequency spectrum is within the allowable range. Is preferred.

  Accordingly, the step of determining the suitability of the size of the hole performed by the hole inspecting unit only determines whether or not the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range. The suitability of the size of the hole formed in the component can be instantaneously determined, and the hole formed in the inspection target component can be inspected in a short time.

[9] In the hole inspection method of the present invention, the spectral component is a resonance frequency,
"Correlation between the spectral components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" means the resonance frequency and the master sample existing in each resonance frequency spectrum of each sample. Correlation with the size of the hole formed in each sample including, when the resonance frequency existing in the resonance frequency spectrum of the master sample is the reference resonance frequency, the step of determining the suitability of the size of the hole, It is preferable to determine the suitability of the hole formed in the inspection target component based on the reference resonance frequency and the resonance frequency existing in the inspection target resonance frequency spectrum.

  This may cause a clear difference between the resonance frequency (reference resonance frequency) existing in the resonance frequency spectrum of the master sample and the resonance frequency existing in the resonance frequency spectrum to be inspected. The suitability of the hole formed in the inspection target component can be determined based on the resonance frequency existing in the resonance frequency spectrum and the resonance frequency existing in the inspection target resonance frequency spectrum.

  [10] In the hole inspection method of the present invention, an allowable range for determining the suitability of the hole size is set to the reference resonance frequency, and the step of determining the suitability of the hole size includes: It is preferable to determine whether or not the size of the hole formed in the inspection target component is appropriate by determining whether or not the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range.

  Thereby, the step of determining the suitability of the size of the hole performed by the hole inspecting section only determines whether or not the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range. The suitability of the size of the formed hole can be determined instantly, and the hole formed in the inspection target component can be inspected in a short time.

  [11] In the hole inspection method of the present invention, it is preferable that the master sample and the inspection target component have the same thickness, and the inspection of the size of the hole is an inspection of the diameter of the hole.

  As a result, the diameter of the hole of the inspection target component (hole diameter) can be inspected with high accuracy in a short time.

  [12] In the hole inspection method of the present invention, a plurality of the holes are provided in one inspection target component, the plurality of holes can simultaneously pass the fluid or the light, and the microphone is It is preferable to output an electric signal that depends on the flow rate of gas that passes through the plurality of holes at the same time.

  According to the hole inspection method of the present invention, it is possible to inspect an inspection target component in which a plurality of holes are formed in one inspection target component.

  [13] The hole inspection device of the present invention is a hole inspection device for inspecting a hole formed in a component to be inspected and capable of passing a fluid or light. The hole inspection device has a space inside and an opening on one surface. And a sound that is provided on the side opposite to the surface having the opening in the space formed in the housing and that is sealed except for the opening, and outputs sound toward the side of the opening. Speaker, a speaker driving unit that sweeps a frequency within a predetermined range within a predetermined time with respect to the speaker, and a speaker unit installed at a predetermined position in the space and having a part having the hole so as to cover the opening. A microphone that outputs an electric signal that depends on the flow rate of the gas passing through the hole when the speaker drive section sweeps the frequency of the speaker in a fixed state, and an electric signal that is output from the microphone. Frequency analysis, a frequency analysis unit that generates a resonance frequency spectrum in which a resonance frequency exists, and a hole inspection unit that inspects the size of the hole based on the resonance frequency spectrum generated by the frequency analysis unit, The frequency analysis unit is provided with a hole that is confirmed to be capable of passing a predetermined amount of fluid or light, and a master sample for inspecting the inspection target component, and the master sample. A plurality of samples, each of which has a size different from the size of the size of the holes formed in the above, and which is confirmed to be able to pass a predetermined amount of fluid or light, and the opening of the housing. The master obtained by frequency-analyzing the electric signal output from the microphone when the speaker is frequency-swept in a state of being placed so as to cover the Sample and the plurality of samples, and further has a function of obtaining a correlation between a spectral component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample, and the hole inspection unit. Is a resonance frequency spectrum to be inspected obtained by frequency-analyzing an electric signal output from the microphone when the speaker is frequency-swept in a state where the inspected component is placed so as to cover the opening. Formed in the inspection target component based on the included spectrum component and “the correlation between the spectrum component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample” It is characterized by having a function of inspecting the size of the hole that is present.

  According to the hole inspection apparatus of the present invention, the same effects as those of the hole inspection method of the present invention described in [1] above can be obtained. The hole inspection apparatus of the present invention also preferably has the same characteristics as the hole inspection method of the present invention described in [2] to [12] above.

It is a figure shown in order to demonstrate Helmholtz resonance. It is a figure shown in order to demonstrate the hole inspection apparatus 10 which concerns on Embodiment 1. It is a figure which shows an example of a test sample. It is a figure which shows roughly the frequency-analysis part result of test sample SP1-SP6. It is a figure which shows the frequency spectrum (1st resonance frequency spectrum) in which the 1st resonance frequency f1 in FIG. 4 exists for each sample SP1-SP6 in detail. It is a figure which shows the frequency spectrum (2nd resonance frequency spectrum) in which the 2nd resonance frequency f2 in FIG. 4 exists for each sample SP1-SP6 in detail. It is a figure which shows in detail the frequency spectrum (3rd resonance frequency spectrum) in which the 3rd resonance frequency f3 in FIG. 4 exists for each sample SP1-SP6. 7 is a flowchart illustrating a process for obtaining a correlation between a spectral component included in a resonance frequency spectrum of each sample and a size of a hole formed in each sample. It is a flowchart which shows the process for inspecting an inspection target component. It is a figure shown in order to demonstrate the fine hole inspection apparatus 900 described in patent document 1.

  Hereinafter, Embodiment 1 of the present invention will be described. In the first embodiment of the present invention described below, the inspection target component is thin (for example, about 0.05 mm to several mm) and has a disc shape. For example, the description will be made assuming that one hole having a diameter of about 0.5 mm to several mm is formed, but the number of holes formed on the inspection target component is not one, and for example, the diameter is about several μm. A large number of fine holes may be formed. In the hole inspection method and hole inspection apparatus of the present invention, the parts to be inspected are not limited to such parts.

  Further, the hole inspection method and the hole inspection apparatus of the present invention are based on an electric signal (electric signal output from a microphone) depending on the flow rate of gas (air) passing through the hole formed in the inspection target component. Since the inspection is performed, it is possible to inspect the hole size including the plane size of the hole and the depth of the hole. In each of the following embodiments, it is assumed that the “hole size” is the hole diameter, and a case in which the diameter (hole diameter) of the hole formed in the inspection target component having a constant thickness is inspected will be described.

[Embodiment 1]
In the hole inspection method and the hole inspection apparatus according to the first embodiment, it is determined whether or not the size of the hole is appropriate, that is, whether or not the hole diameter is the target hole diameter (determination of whether or not the hole diameter is appropriate). First, the hole inspection device 10 according to the first embodiment will be described.

  FIG. 2 is a diagram shown for explaining the hole inspection apparatus 10 according to the first embodiment. 2 is a sectional view schematically showing the structure of the hole inspection device 10 according to the first embodiment.

  As shown in FIG. 2, the hole inspection apparatus 10 according to the first embodiment has a space 101 formed therein, an opening 102 formed in one surface (referred to as an upper surface), and the opening 102 is formed. Is provided on the side opposite to the surface of the housing 100 in which the surface other than the surface is sealed and the surface in which the opening 102 is formed in the space portion 101 formed in the housing 100. A speaker 110 that outputs a sound toward the speaker 110, a speaker driving unit 120 that sweeps a frequency within a predetermined range within a predetermined time with respect to the speaker 110, and a component 200 that is installed at a predetermined position of the space 101 and has a hole 201 are provided. Depends on the flow rate of air passing through the hole 201 when the speaker driving unit 120 is frequency-swept with respect to the speaker 110 within a predetermined time while being placed so as to cover the opening 102. A microphone 130 that outputs an electric signal (sine wave signal), a frequency analysis unit 140 that performs a frequency analysis (fast Fourier transform: FFT analysis) on the electric signal output from the microphone 130 to generate a resonance frequency spectrum, and a frequency A hole inspection unit 150 that inspects the size of the hole formed in the inspection target component (determines whether the hole diameter is appropriate) based on the resonance frequency spectrum generated by the analysis unit 140.

In such a configuration, when inspecting the size of the hole formed in the component to be inspected (determining the suitability of the hole diameter), it is first confirmed that the fluid or light can pass in a predetermined amount. It is confirmed that a master sample having holes formed therein and a hole having a size different from the size of the holes formed in the master sample are formed, and that a predetermined amount of fluid or light can pass through. The plurality of samples are used, and the speaker driving unit 120 sets the frequency of the speaker 110 to the frequency in the state where the samples are sequentially placed so as to cover the opening 102 of the housing 100 for each sample including the master sample and the plurality of samples. The frequency analysis unit 140 performs a frequency analysis (FFT analysis) on the sweeping step and the electric signal output from the microphone 130 to determine the resonance frequency of each sample. Generating a spectrum, the step of obtaining a correlation between the size of the holes formed in each sample and the spectral components contained in the resonance frequency spectrum of each sample performed. In this way, "the correlation between the spectral components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" is obtained.
Then, when inspecting the appropriateness of the hole diameter of the hole formed in the inspection target component, in the state where the inspection target component is placed so as to cover the opening, the speaker driving section 120 sweeps the frequency of the speaker 110. The step of performing frequency analysis (FFT analysis) by the frequency analysis unit 140 on the electric signal output from the microphone 130 to generate an inspection target resonance frequency spectrum corresponding to the inspection target component is included in the inspection target resonance frequency spectrum. Is formed on the inspection object component based on the spectrum component and "the correlation between the spectrum component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample". A step of inspecting the size of the hole (determination of suitability of the hole diameter).

  In the hole inspection method according to the first embodiment, the step of inspecting the size of the hole formed in the inspection target component (determination of suitability of the hole diameter) is performed in the resonance frequency spectrum of each sample described above. The suitability of the hole diameter of the hole formed in the inspection target component is determined based on the spectral component included in the resonance frequency spectrum of the master sample and the spectral component included in the inspection target resonance frequency spectrum. A specific example of the processing for determining the suitability of the hole diameter of the hole formed in the inspection target component will be described later.

  Among the above steps, the step of obtaining the correlation may be performed by the frequency analysis unit 140 or the hole inspection unit 150, but here, the frequency analysis unit 140 is performed. The process performed by the frequency analysis unit 140 and the process performed by the hole inspection unit 150 can be realized by the arithmetic function of an information processing device such as a personal computer. The step of sweeping the frequency of the speaker 110 may be performed by using a device capable of sweeping the frequency of the speaker 110. Alternatively, an information processing device such as a personal computer may have a frequency sweep function for the speaker 110. You may make it do it.

  The hole inspection apparatus 10 according to the first embodiment will be described more specifically. The housing 100 has a tubular shape (for example, a cylindrical shape), and an opening 102 is provided on the upper surface. A partition plate 105 for partitioning the space portion 101 into upper and lower parts is provided in the space portion 101 formed inside the housing 100, and a speaker 110 is attached to the partition plate 105. The speaker 110 is attached to the partition plate 105 so that a diaphragm (not shown) faces the opening 102 side.

  The partition plate 105 is provided in the housing 100 at a position close to the bottom surface 106. Therefore, the space portion 101 is divided into a space portion 101a between the partition plate 105 and the opening 102 and a space portion 101b between the partition plate 105 and the bottom surface 106, but the space portion 101b is mainly a speaker. This is to secure a mounting space for 110 between the bottom surface 106.

  The size of the housing 100 configured in this way is not particularly limited, but in the hole inspection apparatus 10 according to the first embodiment, the diameter (inner diameter) is 60 mm, and the space portion of the housing 100. It is assumed that the height from the (space 101a) to the opening 102 is 65 mm.

  On the other hand, the microphone 130 is a high-sensitivity microphone that can receive weak sound with high precision, and uses a microphone called a standard microphone.

  In the hole inspection apparatus 10 according to the first embodiment, the microphone 130 has the sound input unit 131 of the microphone 130 located in the space 101a on the side surface of the housing 100, and between the speaker 110 and the opening 102. It will be installed in the middle position. The installation position of the microphone is not particularly limited, and the microphone may be installed near the opening 102. However, since the component 200 is placed near the opening 102, it may be difficult to install the component 200. In the hole inspection apparatus 10 according to the first embodiment, the side surface of the housing 100 is used. It has been confirmed by a test that the same electric signal can be obtained in the case of being installed on the side surface of the housing 100 and in the case of being installed near the opening 102.

  Further, a component mounting portion 107 on which the component 200 can be mounted so as to cover the opening 102 is formed on the upper surface of the housing 100. In addition, in the hole inspection apparatus 10 according to the first embodiment, since the component 200 has a disc shape, the opening 102 has a circular shape, and the component mounting portion 107 has a peripheral portion of the disc-shaped component 200. It can be supported. A component holding unit 108 is provided to fix the component 200 so that the component 200 is not displaced when the component 200 is placed on the component placement unit 107. The component pressing portion 108 is also provided with a circular opening 109 like the opening 102 of the housing 100, and is configured to press the peripheral portion of the component 200. In addition, in FIG. 2, the hole 201 of the component 200 is shown as one, but a large number of holes may be formed. When a large number of holes are formed, all the holes are mounted on the component mounting portion 107 so as to face the openings 102.

  It should be noted that although FIG. 2 is a schematic diagram, illustration is omitted, but when the component 200 is mounted on the component mounting portion 107, the component 200 and the component mounting portion 107 are in a sealed state. It is structured so that it can be placed.

  By the way, the speaker drive unit 120 sweeps a frequency in a predetermined range with respect to the speaker 110 within a predetermined time. In the hole inspection apparatus according to the first embodiment, the frequency of 1 Hz to 10 KHz is changed in 15 seconds. Shall be swept.

  The component 200 mounted on the component mounting unit 107 includes both the inspection target component to be inspected and the master sample. The master sample is a sample for determining the suitability of the size (here, the hole diameter) of the hole formed in the inspection target component, and determines whether the hole size of the hole formed in the inspection target component is appropriate. It is used when acquiring determination data (described later) for determination. That is, when acquiring the determination data, a master sample is mounted as the component 200 on the component mounting unit 107 to acquire the determination data, and when the inspection target component is inspected, An inspection target component is placed as the component 200 on the placement unit 107 to perform the inspection.

  In addition, the master sample is used when acquiring determination data (described later) for determining whether or not the hole diameter of the hole formed in the inspection target component is appropriate, as described above. Therefore, the target hole diameter is provided with high accuracy. For example, when the diameter of the hole formed in the inspection target component is set to 1 mm and the hole diameter of the inspection target component is to be inspected, the master sample is a hole having a hole diameter of 1 mm with high accuracy. Is used. Whether or not the holes formed in the master sample have a precision of 1 mm can be inspected by, for example, a laser microscope.

  By the way, the hole inspection method and the hole inspection apparatus according to the first embodiment are for inspecting the suitability of the hole diameter formed in the inspection target component, but the “hole diameter” is referred to as “inspecting the inspection target component”. It may be abbreviated and described. In addition, if the hole diameter is determined to be appropriate as a result of the determination of the appropriateness of the hole diameter, it is described as "the component to be inspected is an OK part", or the result of the determination of the appropriateness of the hole diameter indicates that the hole diameter is inappropriate. In some cases, it may be described as "the inspection target component is an NG component".

  Next, a test example performed using a plurality of samples (referred to as test samples) in which holes having different hole diameters are formed will be described. In this test, a plurality of test samples in which holes having different hole diameters are formed are prepared, and the plurality of test samples are placed one by one on the component placement unit 107, and the speaker drive unit is tested. When the frequency of the speaker 110 is swept by 120, the frequency analysis unit 140 performs frequency analysis (FFT analysis) on the electric signal (sine wave signal) output from the microphone 130, and the resonance frequency spectrum generated by the result of the analysis is obtained. Generate for each test sample. The resonance frequency spectrum refers to a frequency spectrum in which a resonance frequency exists.

  Then, the relationship between the pore diameter and the resonance frequency spectrum is examined based on the resonance frequency spectrum obtained in each of the test samples having different pore diameters. The following test samples were prepared as the test samples used when performing such a test.

  FIG. 3 is a diagram showing an example of a test sample. FIG. 3A is a diagram showing the hole diameter of each of six test samples SP1 to SP6 (abbreviated as samples SP1 to SP6) having different hole diameters, and FIG. It is a perspective view showing the appearance of sample SP1. As shown in FIG. 3B, the sample SP1 has a disk shape and has a hole 201 formed at the center. The other samples SP2 to SP6 have the same shape. It is assumed that the samples SP1 to SP6 have a constant thickness (the same).

  Here, a sample SP1 having a diameter of 0.5 mm (500 μm), a sample SP2 having a diameter of 0.75 mm (750 μm), a sample SP3 having a diameter of 1.0 mm (1000 μm), and a sample SP4 having a diameter of 1.35 mm (1350 μm). Six types of samples were prepared: a sample SP5 having a diameter of 1.65 mm (1650 μm) and a sample SP6 having a diameter of 2.0 mm (2000 μm). In addition, each of these samples SP1 to SP6 may be described as "0.5 mm sample SP1", "0.75 mm sample SP2", "1.0 mm sample SP3" as the name of each sample.

  The diameters of the holes given as the names of these samples SP1 to SP6 (for example, 0.5 mm, 0.75 mm, 1.0 mm, 1.35 mm, ...) Are the same as those of the holes formed in each sample. The diameter is not exactly represented. For example, the 0.5 mm sample SP1 is a sample having an actual hole diameter of 0.507 mm (507.0 μm) when measured with a microscope (for example, a laser microscope) capable of highly accurate measurement, and 0.75. Similarly, the sample SP2 is a sample having an actual hole diameter of 0.7563 mm (756.3 μm) when measured with a microscope capable of highly accurate measurement, and the 1.0 sample SP3 is also highly accurate. When measured with a microscope capable of measurement, the sample has an actual pore diameter of 0.9941 mm (994.1 μm). The same applies to the other samples SP4 to SP6 (see FIG. 3A).

  FFT analysis was performed using such six types of samples SP1 to SP6. That is, when six types of samples SP1 to SP6 are sequentially placed one by one on the component placement unit 107 of the hole inspection apparatus 10 shown in FIG. The frequency analysis unit 140 performs a frequency analysis (FFT analysis) on the electric signal thus generated. Here, the speaker driving unit 120 sweeps the frequency of the speaker 110 in the range of 1 Hz to 10 KHz for 15 seconds.

FIG. 4 is a diagram schematically showing the results of the frequency analysis unit of the samples SP1 to SP6. Note that, in FIG. 4, one sample each of SP1 to SP6 is placed on the component placement section 107 of the hole inspection apparatus 10 shown in FIG. 1, and the speaker driving section 120 sets the speaker 110 to 15 in the range of 1 Hz to 10 KHz. It is a figure which shows the resonance frequency spectrum obtained by FFT-analyzing the electric signal (sine wave signal) output from the microphone 130 by the frequency analysis part 140, when a frequency sweep is carried out for a second, and a horizontal axis is a frequency (Hz). And the vertical axis represents the FFT amplitude value (V ² / Hz). The FFT amplitude value may be simply referred to as “amplitude value”.

  As shown in FIG. 4, the resonance frequencies f1, f2, and f3 are obtained in the samples SP1 to SP6, the resonance frequency f1 (referred to as the first resonance frequency f1) has a large amplitude, and the resonance frequency f2 (the second resonance frequency). The amplitude of the frequency f2) and the resonance frequency f3 (referred to as the third resonance frequency f3) are smaller than that of the first resonance frequency. This was common to samples SP1-SP6.

  In this case, three resonance frequencies (the first resonance frequency f1, the second resonance frequency f2, and the third resonance frequency f3) are obtained as the resonance frequencies. This is the hole inspection apparatus 10 used in the test. It depends on the shape, size, etc. of the housing 100 of FIG. 1. In the hole inspection apparatus 10 used in the test, three resonance frequencies were obtained as shown in FIG. Depending on the shape, size, etc., only one may be obtained, or four or more may be obtained.

FIG. 5 is a diagram for explaining in detail the portion of the first resonance frequency f1 in FIG. FIG. 5A is a diagram showing in detail six patterns of resonance frequency spectra for each of the samples SP1 to SP6 (the six patterns of resonance frequency spectra are collectively referred to as a first resonance frequency spectrum). In FIG. 5A, the horizontal axis represents frequency (Hz) and the vertical axis represents FFT amplitude value (V ² / Hz). Here, the resonance frequency is a frequency at which the maximum value of the amplitude exists in the resonance frequency spectrum.

Further, FIG. 5B is a diagram showing the relationship between the hole diameter and the FFT amplitude value in the first resonance frequency spectrum shown in FIG. 5A. In FIG. 5B, the horizontal axis represents the hole diameter (mm) and the vertical axis represents the FFT amplitude value (V ² / Hz).

  The "amplitude value" in the "relationship between hole diameter and amplitude value" shown in FIG. 5B is not the amplitude value of the resonance frequency of each sample SP1 to SP6. That is, the amplitude value of the reference sample (here, the sample SP1) is the amplitude value of the resonance frequency 245 Hz of the sample SP1 (the maximum amplitude value of the resonance frequency spectrum obtained in the sample SP1). However, the amplitude values of the other samples SP2 to SP6 are not the amplitude values of the resonance frequencies of the respective samples SP2 to SP6 (the maximum value of the amplitude value of the resonance frequency spectrum obtained in each sample), but of the reference sample SP1. It is the amplitude value of each sample SP1 to SP6 at the resonance frequency (245 Hz). That is, in FIG. 5A, it is the amplitude value existing on the reference line L1 indicated by the broken line passing through the resonance frequency (245 Hz) of the reference sample SP1.

The resonance frequency of the reference sample SP1 is referred to as "reference resonance frequency", and the amplitude value of the reference sample SP1 at the reference resonance frequency is referred to as "reference amplitude value". Therefore, in this case, the resonance frequency 245 Hz of the sample SP1 is the “reference resonance frequency”, and the amplitude value 2281V ² / Hz of the sample SP1 is the “reference amplitude value”.

  Referring to FIG. 5, the first resonance frequency spectrum will be considered for each of the samples SP1 to SP6. The reference resonance frequency of the sample SP1 (0.5 mm sample SP1) is the reference resonance frequency f11, and the resonance frequencies of the samples SP2 to SP4 are the resonance frequencies f12 to f16.

  According to FIG. 5, the resonance frequencies f12 to f14 of the samples SP2 to SP4 are substantially the same as the reference resonance frequency f11, and the resonance frequencies f15 and f16 of the samples SP5 and SP6 are also set to the reference resonance frequency f11. There are some differences, but no big difference.

  On the other hand, there is a difference in the amplitude value of each sample SP1 to SP6. Here, focusing on the amplitude values of the samples SP1 to SP6 at the reference resonance frequency f11 (amplitude values on the reference line L1 in FIG. 5A), the amplitude values of the samples SP1 to SP6 are significantly different.

That is, focusing on the amplitude value on the reference line L1 in FIG. 5A, the amplitude value (reference amplitude value) of the sample SP1 is 2281 V ² / Hz from FIG. The amplitude value (amplitude value on the reference line L1 in FIG. 5A) is 2045 V ² / Hz from FIG. 5A, and the amplitude value of the 1.0 mm sample SP3 (reference line L1 in FIG. 5A). 5A is 1789 V ² / Hz, and the amplitude value of the 1.35 mm sample SP4 (the amplitude value on the reference line L1 in FIG. 5A) is shown in FIG. ) To 1379 V ² / Hz, the amplitude value of the 1.65 mm sample SP5 (amplitude value on the reference line L1 in FIG. 5A) is 1084 V ² / Hz from FIG. Amplitude value of SP6 (Fig. 5 ( The amplitude value on the reference line L1 in a) is 866 V ² / Hz from FIG. 5A.

  Here, when the hole diameters of the samples SP1 to SP6 are associated with the amplitude values (amplitude values on the reference line L1) of the samples SP1 to SP6, the hole diameters and the amplitude values (amplitude values on the reference line L1) are shown in FIG. It can be seen that there is a correlation as shown in (b). As shown in FIG. 5B, the amplitude values (amplitude values on the reference line L1) from the sample SP1 (0.5 mm sample SP1) to the sample SP6 (2.0 mm sample SP6) can be connected by a straight line. The amplitude value on the reference line L1 is the amplitude value of the resonance frequency spectrum of each of the samples SP1 to SP6 at the reference resonance frequency f11. As described above, the first resonance frequency spectrum (see FIG. 5A) is included in the resonance frequency spectrum of each of the samples SP1 (0.5 mm sample) to sample SP6 (2.0 mm sample). It can be seen that there is a correlation between the spectrum component (in this case, the amplitude value (the amplitude value on the reference line L1)) and the hole diameter.

FIG. 6 is a diagram illustrating in detail the portion of the second resonance frequency f2 in FIG. FIG. 6A is a diagram showing in detail six patterns of resonance frequency spectra for each of the samples SP1 to SP6 (the six patterns of resonance frequency spectra are collectively referred to as a second resonance frequency spectrum). In FIG. 6A, the horizontal axis represents frequency (Hz) and the vertical axis represents FFT amplitude value (V ² / Hz).

Further, FIG. 6B is a diagram showing the relationship between the hole diameter and the FFT amplitude value in the second resonance frequency spectrum shown in FIG. 6A. In FIG. 6B, the horizontal axis represents the hole diameter (mm) and the vertical axis represents the FFT amplitude value (V ² / Hz).

  The "amplitude value" in the "relationship between hole diameter and amplitude value" shown in FIG. 6B is not the amplitude value of the resonance frequency of each sample SP1 to SP6. That is, the amplitude value of the reference sample (also referred to as the sample SP1 here) is the amplitude value of the resonance frequency 1495 Hz of the sample SP1 (the maximum value of the amplitude value of the resonance frequency spectrum obtained in the sample SP1). , The amplitude values of the other samples SP2 to SP6 are not the amplitude values of the resonance frequencies of the respective samples SP2 to SP6 (the maximum value of the amplitude values of the resonance frequency spectrum obtained in each sample), but the resonance of the reference sample SP1. It is an amplitude value of each sample SP2-SP6 in a frequency (1495 Hz). That is, in FIG. 6A, it is the amplitude value existing on the reference line L2 shown by the broken line passing through the resonance frequency (1495 Hz) of the reference sample SP1.

Here, again, the resonance frequency of the reference sample SP1 is referred to as a "reference resonance frequency", and the amplitude value of the reference sample SP1 at the reference resonance frequency is referred to as a "reference amplitude value". Therefore, in this case, the resonance frequency 1495 Hz of the sample SP1 is the “reference resonance frequency”, and the amplitude value 352 V ² / Hz of the sample SP1 is the “reference amplitude value”.

  The second resonance frequency spectrum will be considered for each of the samples SP1 to SP6 with reference to FIG. The reference resonance frequency of the sample SP1 (0.5 mm sample SP1) is set to the reference resonance frequency f21, and the resonance frequencies of the samples SP2 to SP4 are set to the resonance frequencies f22 to f26.

  According to FIG. 6, the resonance frequency (resonance frequency f21) of the sample SP1 (0.5 mm sample SP1) is 1495 Hz, and the resonance frequencies f22 to f26 also increase little by little as the hole diameter increases. The amplitude value is also gradually increasing.

  Here, focusing on the amplitude value of each sample SP1 to SP6 at the reference resonance frequency f21 (amplitude value on the reference line L2 in FIG. 6A), the amplitude value of each sample SP1 to SP6 (in FIG. 6A) Amplitude values on the reference line L2 are greatly different.

That is, focusing on the amplitude value on the reference line L2 in FIG. 6A, the amplitude value (reference amplitude value) of the sample SP1 is 352 V ² / Hz from FIG. The amplitude value (amplitude value on the reference line L2 in FIG. 6A) is 331 V ² / Hz from FIG. 6A, and the amplitude value of the 1.0 mm sample SP3 (reference line L2 in FIG. 6A). 6A is 294 V ² / Hz, and the amplitude value of the 1.35 mm sample SP4 (the amplitude value on the reference line L2 in FIG. 6A) is shown in FIG. 6A. From 264 V ² / Hz, the amplitude value of the 1.65 mm sample SP5 (amplitude value on the reference line L2 in FIG. 6A) is 238 V ² / Hz from FIG. 6A, and the 2.0 mm sample SP6. The amplitude value of the The amplitude value on the quasi-line L2) is 211 V ² / Hz from FIG. 6 (a).

  Here, when the hole diameter of each sample SP1 to SP6 and the amplitude value (amplitude value on the reference line L2) of each sample SP1 to SP6 are associated, the hole diameter and the amplitude value (amplitude value on the reference line L2) are shown in FIG. It can be seen that there is a correlation as shown in (b). As shown in FIG. 6B, the amplitude values (amplitude values on the reference line L2) from the sample SP1 (0.5 mm sample SP1) to the sample SP6 (2.0 mm sample SP6) can be connected by a straight line. The amplitude value on the reference line L2 is the amplitude value of the resonance frequency spectrum of each sample SP1 to SP6 at the reference resonance frequency f21. As described above, the second resonance frequency spectrum (see FIG. 6A) is included in the resonance frequency spectrum for each of the samples SP1 (0.5 mm sample) to sample SP6 (2.0 mm sample). It can be seen that there is a correlation between the spectrum component (in this case, the amplitude value (the amplitude value on the reference line L2)) and the hole diameter.

FIG. 7 is a diagram illustrating in detail the portion of the third resonance frequency f3 in FIG. FIG. 7A is a diagram showing in detail six patterns of resonance frequency spectra for each of the samples SP1 to SP6 (the six patterns of resonance frequency spectra are collectively referred to as a third resonance frequency spectrum). In FIG. 7A, the horizontal axis represents frequency (Hz) and the vertical axis represents FFT amplitude value (V ² / Hz). Here, the resonance frequency is a frequency at which the maximum value of the amplitude exists.

Further, FIG. 7B is a diagram showing the relationship between the hole diameter and the FFT amplitude value in the second resonance frequency spectrum shown in FIG. 7A. In FIG. 7B, the horizontal axis represents the hole diameter (mm) and the vertical axis represents the FFT amplitude value (V ² / Hz).

  The "amplitude value" in the "relationship between hole diameter and amplitude value" shown in FIG. 7B is not the amplitude value of the resonance frequency of each sample SP1 to SP6. That is, the amplitude value of the reference sample (also referred to as sample SP1 here) is the amplitude value of the resonance frequency 4584 Hz of the sample SP1 (the maximum value of the amplitude value of the resonance frequency spectrum obtained in the sample SP1). However, the amplitude values of the other samples SP2 to SP6 are not the amplitude values of the resonance frequencies of the respective samples SP2 to SP6 (the maximum value of the amplitude value of the resonance frequency spectrum obtained in each sample), but of the reference sample SP1. It is the amplitude value of each sample SP1 to SP6 at the resonance frequency (4584 Hz). That is, in FIG. 7A, it is the amplitude value existing on the reference line L3 indicated by the broken line passing through the resonance frequency (4584 Hz) of the sample SP1 serving as the reference.

Here, again, the resonance frequency of the reference sample SP1 is referred to as a "reference resonance frequency", and the amplitude value of the reference sample SP1 at the reference resonance frequency is referred to as a "reference amplitude value". Therefore, in this case, the resonance frequency 4584 Hz of the sample SP1 is the “reference resonance frequency”, and the amplitude value 81.1 V ² / Hz of the sample SP1 is the “reference amplitude value”.

  Referring to FIG. 7, the third resonance frequency spectrum will be considered for each of the samples SP1 to SP6. The reference resonance frequency of the sample SP1 (0.5 mm sample SP1) is the reference resonance frequency f31, and the resonance frequencies of the samples SP2 to SP4 are the resonance frequencies f32 to f36.

  According to FIG. 7A, the resonance frequencies of the test samples SP1 to SP6 increase little by little as the hole diameter increases, but the amplitude value hardly changes. Here, assuming that the resonance frequency f31 (4584 Hz) of the 0.5 mm sample SP1 is the reference resonance frequency f31, the amplitude value of each sample SP1 to SP6 at the reference resonance frequency f31 (4584 Hz) (reference in FIG. 7A) Focusing on the (amplitude value on the line L2), the amplitude values of the samples SP1 to SP6 (amplitude values on the reference line L3 in FIG. 7A) are significantly different.

That is, focusing on the amplitude value on the reference line L3 in FIG. 7A, the amplitude value (reference amplitude value) of the sample SP1 is 81.1V ² / Hz from FIG. The amplitude value of SP (the amplitude value on the reference line L3 in FIG. 7A) is 76.2V ² / Hz from FIG. 7A, and the amplitude value of the 1.0 mm sample SP3 (FIG. 7A). The amplitude value on the reference line L3 in FIG. 7 is 67.8 V ² / Hz from FIG. 7A, and the amplitude value of the 1.35 mm sample SP4 (the amplitude value on the reference line L3 in FIG. 7A) is 7A is 57.0V ² / Hz, and the amplitude value of the 1.65 mm sample SP5 (the amplitude value on the reference line L3 in FIG. 7A) is 50.4V ² from FIG. 7A. / Hz, and the amplitude value of the 2.0 mm sample SP6 (Fig. 7 (a) The amplitude value on the reference line L3) is 44.5 V ² / Hz from FIG. 7 (a).

  Here, when the hole diameter of each sample SP1 to SP6 and the amplitude value of each sample SP1 to SP6 (the amplitude value on the reference line L3 in FIG. 7A) are associated, the hole diameter and the amplitude value (in FIG. 7A) are associated. It can be seen that there is a correlation with the amplitude value on the reference line L3) as shown in FIG. As shown in FIG. 7B, the amplitude values (amplitude values on the reference line L3 in FIG. 7A) from the sample SP1 (0.5 mm sample SP1) to the sample SP6 (2.0 mm sample SP6) are straight lines. You can tie. In this case as well, the amplitude value on the reference line L3 is the amplitude value of the resonance frequency spectrum corresponding to each of the samples SP1 to SP6 at the reference resonance frequency f31. As described above, the third resonance frequency spectrum (see FIG. 7A) is included in the resonance frequency spectrum for each of the samples SP1 (0.5 mm sample) to sample SP6 (2.0 mm sample). It can be seen that there is a correlation between the spectrum component (in this case, the amplitude value (the amplitude value on the reference line L3)) and the hole diameter.

  As shown in FIGS. 5 to 7, in each of the first resonance frequency spectrum, the second resonance frequency spectrum, and the third resonance frequency spectrum, the resonance frequency of one sample (in this case, the resonance frequencies f11, f21, When f31) is the reference resonance frequency, there is a correlation between the amplitude values of the samples SP1 to SP6 (amplitude values on the reference lines L1 to L3) at the reference resonance frequency and the hole diameters of the samples SP1 to SP6. I understood it.

  As described above, the amplitude value (amplitude value on the reference lines L1 to L3) of the resonance frequency spectrum of each sample SP1 to SP6 at the reference resonance frequency and the hole diameter of each sample SP1 to SP6 are as shown in FIG. The correlations shown in FIGS. 6B and 7B can be obtained. Here, the resolution of the amplitude value due to the change in the hole diameter will be described.

First, in the case of FIG. 5B, that is, in the case of the first resonance frequency spectrum, the amplitude value in the 0.5 mm sample SP1 is 2281 V ² / Hz, and the amplitude value in the 2.0 mm sample SP6 is 866 V ² /. Since it is Hz, the amount of change in the amplitude value per 1 mm is (2281-866) /1.5≈943.3, and when the hole diameter changes by 1 mm, the amplitude value changes by about 943.3 V ² / Hz. Becomes

Further, in the case of FIG. 6B, that is, in the case of the second resonance frequency spectrum, the amplitude value in the 0.5 mm sample SP1 is 352 V ² / Hz, and the amplitude value in the 2.0 mm sample SP6 is 211 V ² / Hz. Therefore, the amount of change in the amplitude value per 1 mm is (352-211) /1.5=94V ² / Hz, and when the hole diameter changes by 1 mm, the amplitude value changes by 94V ² / Hz.

Further, in the case of FIG. 7B, that is, in the case of the third resonance frequency spectrum, the amplitude value in the 0.5 mm sample SP1 is 81.1 V ² / Hz, and the amplitude value in the 2.0 mm sample SP is 211. Since it is 44.5 V ² / Hz, the amount of change in the amplitude value per 1 mm is (81.1-44.5) /1.5=24.4 when the resolution in is calculated, and the hole diameter changes by 1 mm. Then, the amplitude value changes by 24.4 V ² / Hz.

  Therefore, considering the resolution, it can be said that the highest resolution is obtained in the case of FIG. 5 (in the case of the first resonance frequency spectrum), but in the case of FIG. 6 (in the case of the second resonance frequency spectrum) and in the case of FIG. It was confirmed that also in the case of the third resonance frequency spectrum, the resolution required for inspecting the pore size was obtained.

Specifically, in the case of using the first resonance frequency spectrum, when the hole diameter changes by 1 mm, the amplitude value changes by 943 V ² / Hz. Therefore, the amount of change in the amplitude value per 100 μm of the hole diameter is 94.3 V ² / Hz, and the amount of change in the amplitude value every 10 μm is 9.43 V ² / Hz. Therefore, if an amplitude value of about 94.3 V ² / Hz can be taken, the hole diameter can be inspected with an accuracy of ± 100 μm, and if a difference of about 9.43 V ² / Hz can be taken, an accuracy of ± 10 μm can be obtained. The hole diameter can be inspected with.

In the case of using the second resonance frequency spectrum, the pore size is 1mm change, for changing the amplitude value of about ^94V 2 / Hz, the variation of the amplitude value of each 100μm in pore size at 9.4 V ² / Hz Also, the amount of change in the amplitude value every 10 μm is 0.94 V ² / Hz. Therefore, if it is possible to take the difference of 9.4V approximately ² / Hz as the amplitude value, can check the pore diameter with an accuracy of ± 100 [mu] m, if it is possible to take the difference of about 0.94 V ² / Hz, the ± 10 [mu] m accuracy The hole diameter can be inspected with.

In the case of using the third resonance frequency spectrum, the pore size is 1mm change, the amplitude values vary 24.4V ² / Hz, the variation of the amplitude value of each 100μm of pore size 2.44V ² / Hz In addition, the amount of change in the amplitude value for each 10 μm is 0.244 V ² / Hz. Therefore, if it is possible to take the difference of 2.44V approximately ² / Hz as the amplitude value, can check the pore diameter with an accuracy of ± 100 [mu] m, if it is possible to take the difference of about 0.244V ² / Hz, the ± 10 [mu] m accuracy The hole diameter can be inspected with.

  From this, in any of the case of FIG. 5 (the case of the first resonance frequency spectrum), the case of FIG. 6 (the case of the second resonance frequency spectrum) and the case of FIG. 7 (the case of the third resonance frequency spectrum) It was confirmed that the required resolution was obtained for inspecting the pore size. In particular, when the first resonance frequency spectrum is used, the hole diameter can be inspected with high resolution, so that the hole diameter can be inspected with higher accuracy.

  The test for investigating the relationship between the pore size and the resonance frequency has been described above with reference to FIGS. 3 to 7 by using the samples SP1 to SP6 having different pore sizes, and subsequently, based on the test results described above. A case where an actual inspection is performed on the inspection target component will be described.

  FIG. 8 is a flowchart illustrating a process for obtaining the correlation between the spectral component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample. The term "each sample" used here means a master sample for inspecting a component to be inspected, and a plurality of samples in which holes having different sizes from the holes formed in the master sample are formed. And refers to. It should be noted that each of these samples (master sample and multiple samples) has been confirmed to be capable of passing a predetermined amount of fluid or light (a hole in which the target hole diameter is formed with high accuracy). ) Is formed. When referring to both the master sample and a plurality of samples, they may be referred to as “each sample”.

  Explaining the flowchart shown in FIG. 8, first, for each sample (one for each sample), the speaker 110 is sequentially mounted on the component mounting portion 107 so as to cover the opening 102 of the housing 100. Is swept at a frequency of 1 Hz to 10 KHz for 15 seconds (step S1). Then, the electric signal (sine wave voltage) output from the microphone 130 is subjected to frequency analysis (FFT analysis) to generate a resonance frequency spectrum for each sample (step S2). Then, the correlation between the spectral component (in this case, the amplitude value) included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample is obtained (step 3).

  Here, the resonance frequency spectrum is a resonance frequency spectrum in which a resonance frequency exists, and the resonance frequency is a resonance frequency having the maximum amplitude value in the resonance frequency spectrum.

  The correlation obtained in step S3 is, for example, the correlation shown in FIG. 5 (b), FIG. 6 (b) and FIG. 7 (b). That is, in FIGS. 5B, 6B, and 7B, the reference sample SP1 (0.5 mm sample) is used as a master sample, and the resonance frequencies f11 and f21 of the master sample SP1 are used. , F31 as the reference resonance frequency, the amplitude values of the samples SP1 to SP6 (amplitude values on the reference lines L1 to L3) at the reference resonance frequency and the hole diameters of the samples SP1 to SP6 are shown in FIG. The correlations shown in (b), FIG. 6 (b) and FIG. 7 (b) are obtained. After such a correlation is obtained, the inspection target component is inspected.

  FIG. 9 is a flowchart for explaining the process when inspecting the inspection target component. As shown in FIG. 9, the process for inspecting the component to be inspected is performed by frequency sweeping the speaker 110 at a frequency of 1 Hz to 10 KHz for 15 seconds while the component to be inspected is mounted on the component mounting portion 107 ( In step S10), the microphone 130 inputs the sound of 1 Hz to 10 KHz emitted by the speaker 110, and the frequency analysis unit 140 performs frequency analysis (FFT analysis) on the electrical signal (sine wave signal) output from the microphone 130, A resonance frequency spectrum (referred to as an inspection target resonance frequency spectrum) obtained in the inspection target component is generated (step S20).

  Then, in the hole inspection unit 150, the spectrum component included in the resonance frequency spectrum of the master sample (referred to as the reference resonance frequency spectrum) of the resonance frequency spectra of each sample generated in step S2 of FIG. Based on the (amplitude value) and the spectral component (amplitude value) included in the inspection target resonance frequency spectrum generated in step S20 of FIG. 9, the suitability of the hole formed in the inspection target component is determined ( Step S30).

  In step S30 in FIG. 9, the suitability of the hole formed in the inspection target component with respect to the hole formed in the master sample is determined based on the reference resonance frequency spectrum and the inspection target resonance frequency spectrum. In addition, in the hole inspection method according to the first embodiment, determining the suitability of the hole formed in the inspection target component with respect to the hole formed in the master sample means the diameter of the hole formed in the master sample. It is to judge the suitability of the diameter (hole diameter) of the hole formed in the inspection target component with respect to (hole diameter).

  The hole suitability determination (step S30) performed by the hole inspecting unit 150 is, specifically, as shown in the broken line frame in FIG. 9, the amplitude value ( It is determined whether the amplitude value of the inspection target spectrum at the reference resonance frequency is within an allowable range (a specific example will be described later) (step S31). If the component is an OK component and is not within the allowable range, the component to be inspected is an NG component (step S32).

  Next, a specific inspection example when an actual inspection is performed (when an inspection target component is inspected) will be described. In the inspection example here, in the case of inspecting whether or not the diameter of the hole formed in the inspection target component is the target diameter (here, 0.507 mm (507 μm)). Will be described.

  Here, it is assumed that a master sample for inspecting the inspection target component has already been prepared. It is assumed that the master sample has been confirmed by inspection with a laser microscope or the like to have a hole with a target diameter of 0.507 mm (507 μm) with high accuracy. This is used as a master sample. With respect to the hole diameter of such a master sample, the inspection target component is inspected with a tolerance of ± 10 μm, for example. Therefore, if the diameter of the hole formed in the inspection target component is within 507 μm ± 10 μm, the inspection target component is an OK component.

  The master sample in this case is the 0.5 mm sample SP1 shown in FIG. 3, and the amplitude values (amplitude values on the reference lines L1 to L3) of the samples SP1 to SP6 at the reference resonance frequency of the master sample and It is assumed that the correlations between the pore diameters of the samples SP1 to SP6 are obtained as shown in FIG. 5 (b), FIG. 6 (b) and FIG. 7 (c). Therefore, three resonance frequencies f11, f21, and f31 are obtained in the master sample (denoted as master sample SP1). These three resonance frequencies f11, resonance frequencies f21, and resonance frequencies f31 are referred to as reference resonance frequency f11, reference resonance frequency f21, and reference resonance frequency f31.

(Inspection example 1)
In the inspection example 1, it is assumed that the inspection target component is inspected using the resonance frequency spectrum (first resonance frequency spectrum) in which the reference resonance frequency f11 (245 Hz: see FIG. 5A) exists. The amplitude value at the reference resonance frequency f11 of the master sample SP1 is referred to as a “reference amplitude value”, and the reference amplitude value is 2281 V ² / Hz as shown in FIG. 5A. The reference resonance frequency f11 is 245 Hz, as shown in FIG. Note that, here, since ± 10 μm is inspected as a permissible error with respect to the hole diameter of the master sample SP1, in the inspection example 1, the permissible range of the amplitude value corresponding to the ± 10 μm permissible error is the reference amplitude value 2281V ^2. / relative Hz, is ^{± 9.43V 2 /Hz(2290.43V 2 /Hz~2271.57V 2 /} Hz).

Then, the reference amplitude value, adequacy of the hole (in this case, pore size propriety of) (with respect to the reference amplitude value ^{2281V 2 / Hz, ± 9.43V 2} / Hz) tolerance for determining the set of Place, hole inspection unit 150, the amplitude value of the inspection target resonance frequency spectrum of the reference resonant frequency is equal to or within the allowable range ^{(2290.43V 2 /Hz~2271.57V 2 / Hz)} .

  By setting such an allowable range, the hole inspection unit 150 determines whether or not the amplitude value (amplitude value on the reference line L1) of the inspection target resonance frequency spectrum at the reference resonance frequency is within the allowable range. By determining, it is possible to determine the suitability of the inspection target component.

  That is, when the inspection target component is inspected, it is output from the microphone 130 when the speaker is frequency-swept for 15 seconds at a frequency of 1 Hz to 10 KHz with the inspection target component placed on the component placement unit 107. The frequency analysis unit 140 performs frequency analysis (FFT analysis) on the electrical signal (sine wave signal).

Then, in the hole inspection unit 150, from the frequency analysis (FFT analysis) result by the frequency analysis unit 140, in the resonance frequency spectrum (inspection object resonance frequency spectrum) of the inspection object component, the inspection object at the reference resonance frequency f11 (245 Hz). seeking amplitude value of the resonance frequency spectrum (amplitude values on the reference line L1) V1, the amplitude value V1 ^is, if entered 2290.43V 2 /Hz~2271.57V in ² / Hz, the component to be inspected Determines that the component has an appropriate hole diameter, and regards the relevant inspection target component as an OK component. On the other hand, if the amplitude value V1 of the inspection target part is not within the 2290.43V ² /Hz~2271.57V in ² / Hz, and determines that the inspected sample does not have a proper pore size, the test object Let the parts be NG parts.

For example, the hole diameter of the inspection target component is slightly larger than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L1) of the inspection target component is 2275V ^2. When there was a / Hz, the 2275V ² / Hz, because it is within the allowable range ^{(2290.43V 2 /Hz~2271.57V 2 / Hz)} , and the component being tested is OK parts.

In addition, the hole diameter of the inspection target component is significantly larger than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L1) of the inspection target component is 2270V ² When was / Hz, the 2270V ² / Hz, because not within the allowable range ^{(2290.43V 2 /Hz~2271.57V 2 / Hz)} , and the component to be inspected is NG component.

On the other hand, when the hole diameter of the inspection target component is smaller than the hole diameter (507 μm) of the master sample SP1, the amplitude value (amplitude value on the reference line L1) of the inspection target resonance frequency spectrum of the inspection target component is the master sample SP1. Is larger than the amplitude value (2281 V ² / Hz).

Therefore, for example, the hole diameter of the inspection target component is slightly smaller than the hole diameter of the master sample SP1 (507 μm), and the amplitude value (amplitude value on the reference line L1) of the inspection target resonance frequency spectrum in the inspection target component is temporarily , assuming that a 2285V ² / Hz, the 2285V ² / Hz, because it is within the allowable range ^{(2290.43V 2 /Hz~2271.57V 2 / Hz)} , and the component being tested is OK parts .

Further, the hole diameter of the inspection target component is significantly smaller than the hole diameter (507 μm) of the master sample SP1, and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L1) of the inspection target component is 2295V ² When was / Hz, the 2295V ² / Hz, because not within the allowable range ^{(2290.43V 2 /Hz~2271.57V 2 / Hz)} , and the component to be inspected is NG component.

  As described above, when the first resonance frequency spectrum is used, the hole diameter can be inspected with high resolution, and therefore the hole diameter can be inspected with higher accuracy. This is because in the first resonance frequency spectrum, the difference between the reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency (amplitude value on the reference line L1) is large due to the difference in the hole diameter. Is.

(Inspection example 2)
In the inspection example 1 described above, the case where the inspection target component in which the hole having the hole diameter of 0.507 mm (507 μm) is formed as the target value is inspected using the first resonance frequency spectrum has been described. In 2, the case where the same inspection target component as in the inspection example 1 is inspected with a tolerance of ± 10 μm using the second resonance frequency spectrum (see FIG. 6) will be described. Incidentally, the allowable range of the amplitude value corresponding to the tolerance of ± 10 [mu] m, to the reference amplitude value ^{352V 2 / Hz, ± 0.94V 2} /Hz(352.94V 2 /Hz~351.06V 2 / Hz) Is.

  In the inspection example 2 as well, when the inspection target component is inspected, the microphone 130 is used when the speaker is frequency swept at a frequency of 1 Hz to 10 KHz for 15 seconds while the inspection target component is mounted on the component mounting portion 107. The frequency analysis unit 140 performs frequency analysis (FFT analysis) on the electrical signal (sine wave signal) output from the device.

Then, in the hole inspection unit 150, based on the frequency analysis (FFT analysis) result by the frequency analysis unit 140, in the resonance frequency spectrum (inspection target resonance frequency spectrum) of the inspection target component, the inspection target at the reference resonance frequency f21 (1495 Hz). seeking amplitude value of the resonance frequency spectrum (amplitude values on the reference line L2) V2, the amplitude V2 is the reference amplitude value ^{352V 2 / Hz, ± 0.94V 2} /Hz(352.94V 2 / if entered Hz~351.06V ² / Hz) in, it determines that the inspected component has the proper pore size to the component to be inspected and OK parts. On the other hand, the amplitude value V2 of the inspected component, the reference amplitude value ^{352V 2 / Hz, ± 0.94V 2} /Hz(352.94V 2 /Hz~351.06V 2 / Hz with respect to the reference amplitude value) If it is not inside, it is determined that the inspection target component does not have an appropriate hole diameter, and the inspection target component is an NG component.

For example, the hole diameter of the inspection target component is slightly larger than the hole diameter of the proper sample (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) of the inspection target component is 351.5 V. When it was ² / Hz, the 351.5V ² / Hz, because it is within the allowable range ^{(352.94V 2 /Hz~351.06V 2 / Hz)} , and the component being tested is OK parts .

Further, the hole diameter of the inspection target component is significantly larger than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) of the inspection target component is 349. When was 0V ² / Hz, the 349.0V ² / Hz, because not within the allowable range ^{(352.94V 2 /Hz~351.06V 2 / Hz)} , and the component to be inspected is NG parts .

In the second resonance frequency spectrum, when the hole diameter of the inspection target component becomes smaller than the hole diameter (507 μm) of the master sample SP1, the amplitude value becomes smaller unlike the case of the first resonance frequency spectrum. Therefore, even when the hole diameter of the inspection target component is smaller than the hole diameter (507 μm) of the master sample SP1, the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) of the inspection target component is the reference amplitude value ( 352V ² / Hz).

  As described above, in the second resonance frequency spectrum, even when the hole diameter of the inspection target component is smaller than the hole diameter of the master sample SP1, the amplitude value of the inspection target resonance frequency spectrum in the inspection target component (the amplitude value on the reference line L2). ) Is a value smaller than the reference amplitude value, but also in this case, whether the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) in the inspection target component is within the allowable range. Whether or not the hole diameter is appropriate can be determined by.

For example, the hole diameter of the inspection target component is slightly smaller than the hole diameter (507 μm) of the master sample SP1, and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) of the inspection target component is 351. When was 3V ² / Hz, the 351.3V ² / Hz, because it is within the allowable range ^{(352.95V 2 /Hz~351.05V 2 / Hz)} , the said component being tested is a OK parts To do.

Further, the hole diameter of the inspection target component is significantly smaller than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L2) of the inspection target component is 349. When was 0V ² / Hz, the 349.0V ² / Hz, because not within the allowable range ^{(352.95V 2 /Hz~351.05V 2 / Hz)} , and the component to be inspected is NG parts .

(Inspection example 3)
In inspection example 3, a case will be described in which the same inspection target components as in inspection examples 1 and 2 are inspected with a tolerance of ± 10 μm using the third resonance frequency spectrum (see FIG. 7). Incidentally, the allowable range of the amplitude value corresponding to the tolerance of ± 10 [mu] m, to the reference amplitude value ^{81.1V 2 / Hz, ± 0.244V 2} /Hz(81.344V 2 /Hz~80.856V 2 / Hz).

  In the inspection example 3 as well, when the inspection target component is inspected, the microphone 130 is used when the speaker is frequency-swept at the frequency of 1 Hz to 10 KHz for 15 seconds while the inspection target component is placed on the component placement unit 107. The frequency analysis unit 140 performs frequency analysis (FFT analysis) on the electrical signal (sine wave signal) output from the device.

Then, in the hole inspection unit 150, from the result of the frequency analysis (FFT analysis) by the frequency analysis unit 140, in the resonance frequency spectrum (inspection target resonance frequency spectrum) of the inspection target component, the inspection target at the reference resonance frequency f31 (4584 Hz). The amplitude value (amplitude value on the reference line L3) V3 of the resonance frequency spectrum is obtained, and the amplitude value V3 is ± 0.244V ² / Hz (81.344V) with respect to the reference amplitude value 81.1V ² / Hz. if entered ^{2 /Hz~80.856V 2} / Hz) in, it determines that the inspected component has the proper pore size to the component to be inspected and OK parts. On the other hand, the amplitude value V3 of the inspected part, if not within ^{± 0.244V 2 /Hz(81.344V 2 /Hz~80.856V 2 /} Hz), the component being tested is a proper pore size Yes It is determined that it has not been performed, and the inspection target component is determined to be an NG component.

For example, the hole diameter of the inspection target component is slightly larger than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) of the inspection target component is 81. When was 0V ² / Hz, the 81.0V ² / Hz, because it is within the allowable range ^{(81.344V 2 /Hz~80.856V 2 / Hz)} , the said component being tested is a OK parts To do.

Further, the hole diameter of the inspection target component is significantly larger than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) of the inspection target component is 80. When was 0V ² / Hz, the 80.0V ² / Hz, because not within the allowable range ^{(81.344V 2 /Hz~80.856V 2 / Hz)} , and the component to be inspected is NG parts .

In the third resonance frequency spectrum, as in the case of the second resonance frequency spectrum, when the hole diameter of the inspection target component becomes smaller than the hole diameter (507 μm) of the master sample SP1, the amplitude value becomes smaller. Therefore, even when the hole diameter of the inspection target component is smaller than the hole diameter of the master sample SP1 (507 μm), the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) of the inspection target component is the reference amplitude value ( 81.1V ² / Hz) than a small value. Also in this case, as in the case of the second resonance frequency spectrum described above, the hole diameter depends on whether the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) in the inspection target component is within the allowable range. The suitability of can be determined.

For example, the hole diameter of the inspection target component is slightly smaller than the hole diameter (507 μm) of the master sample SP1, and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) of the inspection target component is 80. When was 9V ² / Hz, the 80.9V ² / Hz, because it is within the allowable range ^{(81.344V 2 /Hz~80.856V 2 / Hz)} , the said component being tested is a OK parts To do.

Further, the hole diameter of the inspection target component is significantly smaller than the hole diameter of the master sample SP1 (507 μm), and the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L3) of the inspection target component is 80. When was 0V ² / Hz, the 80.0V ² / Hz, because not within the allowable range ^{(81.344V 2 /Hz~80.856V 2 / Hz)} , and the component to be inspected is NG parts .

  In the inspection examples 1 to 3 described above, the case where the inspection target component in which the hole of 0.5 mm (diameter) is formed is inspected has been described, but the inspection target component having another hole diameter is described. Can be inspected as well.

  As described above, in the hole inspection apparatus 10 according to the first embodiment, if the allowable range of the reference amplitude value is set in the hole inspection unit 150, the inspection target component is placed on the component placement unit 107 and the speaker is placed. 110 is frequency-swept, and the output signal from the microphone 130 is FFT-analyzed. In the hole inspection unit 150, the amplitude value (on the reference lines L1 to L3) of the inspection target resonance frequency spectrum at the reference resonance frequency obtained from the FFT analysis result. It is possible to determine whether the inspection target component is an OK component or an NG component only by determining whether or not the amplitude value of is within the allowable range.

  From this, in the hole inspection apparatus 10 according to the first embodiment, the inspection target component can be inspected in a short time, and the hole formed in the inspection target component is inspected with an accuracy of, for example, about ± 10 μm. be able to.

  The hole inspection unit 150 may display information indicating that it is an OK component and information indicating that it is an NG component. For example, various methods such as turning on a blue lamp for OK parts and turning on a red lamp for NG parts can be adopted.

By the way, the number of holes formed in the inspection target component is not limited to one per one inspection target component, and it is also applicable to the case where a plurality of holes are present. For example, in the case where 10000 pieces of a diameter of 0.001 mm (10 μm) (a radius of 0.005 mm (5 μm)) are formed in one inspection target part, the total flatness of 10000 holes is calculated. The area is 0.005 × 0.005 × 3.14 × 10000 = 0.785 mm ² . This is similar to the case where one inspection-to-component has one hole having a diameter of 1 mm if the thickness of the inspection target component is constant (same). That is, the plane area of a hole having a diameter of 1 mm is 0.5 × 0.5 × 3,14 = 0.785 mm ² . Even in the inspection target component in which a large number of holes are formed in this manner, the inspection can be performed in the same manner as the above-described inspection example. In this case, the multiple holes may be formed in a range wider than the diameter of the sound input unit 131 of the microphone 130, for example, in a range scattered over substantially the entire surface of the inspection target component.

  The holes according to the first embodiment can be inspected even when such a large number of holes are formed in a range that is scattered over a range wider than the diameter of the sound input unit 131 of the microphone 130. This is because the inspection apparatus 10 determines whether or not the hole formed in the inspection target component is appropriate based on the reference resonance frequency spectrum and the inspection target resonance frequency spectrum in the master sample.

  As described above, by using the resonance frequency spectrum to judge the suitability of the hole, the planar size of the hole (the hole diameter in the case of a circular hole) formed in the inspection target component is limited by the microphone. In addition, the hole inspection can be performed with high accuracy in a short period of time. As a result, not only one hole but also an inspection target part having a large number of holes formed therein, particularly an inspection target part having a large number of holes scattered over substantially the entire surface of the inspection target part Can be

[Embodiment 2]
In the hole inspection method and the hole inspection apparatus according to the above-described first embodiment, the case where the inspection as to whether or not the hole diameter is the target hole diameter (inspection of suitability of the hole diameter) is performed has been described. In the hole inspection method and the hole inspection apparatus, when inspecting what the diameter of the hole formed in the inspection target component is as the inspection of the size of the hole, that is, the hole diameter itself is obtained (measurement The case will be described. The hole inspection apparatus according to the second embodiment has the same structure as the hole inspection apparatus according to the first embodiment (see FIG. 2). The hole inspection method according to the second embodiment will be described below.

  In the hole inspection method according to the second embodiment, the correlation obtained by the flowchart shown in FIG. 8, that is, the spectral component (amplitude value) included in the resonance frequency spectrum of each sample and the hole formed in each sample. The hole diameter of the component to be inspected can be obtained by using the correlation of the diameters (for example, FIG. 5B, FIG. 6B, and FIG. 7B).

  That is, in a state in which the inspection target component is placed so as to cover the opening, a step of frequency sweeping the speaker, frequency analysis of the electric signal output from the microphone, and an inspection target resonance frequency corresponding to the inspection target component are performed. The step of generating a spectrum, "the correlation between the spectral components (eg, amplitude value) contained in the resonance frequency spectrum of each sample and the size of the hole formed in each sample", and the resonance frequency spectrum to be inspected And the diameter of the hole formed in the component to be inspected based on the spectral component (eg, amplitude value) included in the.

  For example, when the hole diameter of the inspection target component is obtained by using the correlation between the amplitude value and the hole diameter shown in FIG. 5B, the amplitude value of the inspection target resonance frequency spectrum obtained in the inspection target component (FIG. 5). From (amplitude value on the reference line L1 shown in (a)), the hole diameter of the inspection target component can be obtained.

More specifically, when the amplitude value of the inspection target resonance frequency spectrum (amplitude value on the reference line L1 shown in FIG. 5A) obtained in the inspection target component is, for example, 1789 v ² / Hz. 5B, the hole diameter of the component to be inspected can be instantly calculated to be 1.00 mm. In addition, when the amplitude value of the inspection target resonance frequency spectrum obtained in the inspection target component (amplitude value on the reference line L1 shown in FIG. 5A) is, for example, 2045v ² / Hz, 5 (b), it is possible to instantly obtain the hole diameter of the inspection target component such that the hole diameter is 0.75 mm. In this case, the hole diameter can be similarly obtained when using FIGS. 6B and 7B. 5 (b), 6 (b) and 7 (b), the correlation between the amplitude value and the hole diameter is connected by an approximate straight line, so that FIG. 5 (b), FIG. 6 (b) In addition, the hole diameter obtained by using the correlation between the amplitude value and the hole diameter shown in FIG. 7B may include an error. Therefore, it is suitable for the measurement of the hole diameter that does not require accuracy.

  The present invention is not limited to the above-described first embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the following modifications are possible.

  (1) In the first embodiment, based on the reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency (the amplitude value on the reference lines L1 to L3 shown in FIGS. 5 to 7). In the above, the case of determining the suitability of the diameter of the hole formed in the inspection target component has been described, but the difference between the diameter of the hole formed in the master sample and the diameter of the hole formed in the inspection target component is , The reference resonance frequency when it can be extracted as the difference between the amplitude value of the resonance frequency existing in the resonance frequency spectrum of the master sample (reference resonance frequency spectrum) and the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum. Based on the amplitude value of the resonance frequency existing in the spectrum and the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum, It is also possible to determine the appropriateness of diameter made is to have holes.

  In this case, when the amplitude value of the resonance frequency existing in the reference resonance frequency spectrum is used as the reference amplitude value, the reference amplitude value is set with an allowable range for determining the suitability of the diameter of the hole, and the hole inspection is performed. The unit determines whether the diameter of the hole formed in the inspection target component is appropriate by determining whether the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range.

  (2) In the first embodiment, based on the reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency (the amplitude value on the reference lines L1 to L3 shown in FIGS. 5 to 7). In the above, the case of determining the suitability of the diameter of the hole formed in the inspection target component has been described. However, the resonance frequency existing in the resonance frequency spectrum (reference resonance frequency spectrum) of the Mamaster sample and the resonance frequency spectrum of the inspection target are compared. In the case where it can be taken out as the difference between the existing resonance frequencies, based on the resonance frequency existing in the reference resonance frequency spectrum and the resonance frequency existing in the inspection target resonance frequency spectrum, the hole diameter of the hole formed in the inspection target part The suitability can also be determined.

  In this case, when the resonance frequency existing in the reference resonance frequency spectrum is set as the reference resonance frequency, the reference vibration resonance frequency is set with an allowable range for determining the adequacy of the diameter of the hole, and the hole inspection unit The suitability of the diameter of the hole formed in the inspection target component is determined by determining whether the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range.

  (3) Based on the reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency (the amplitude value on the reference lines L1 to L3 shown in FIGS. 5 to 7), The case where the suitability of the diameter of the formed hole is determined has been described, but it is formed on the inspection target component based on the “reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency”. Based on the amplitude value of the resonance frequency existing in the reference resonance frequency spectrum and the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum described in (1) above. "Determining whether or not the diameter of the hole formed in the component to be inspected is appropriate." And "Resonance frequency existing in the reference resonance frequency spectrum and inspection pair" described in (2) above. The hole inspection may be performed by combining any two of “determining the suitability of the hole diameter formed in the inspection target component based on the resonance frequency existing in the resonance frequency spectrum”, The inspection of the holes may be performed by combining all three.

  (4) In the first embodiment, the case where the test is performed using the test sample having the hole diameter of 0.5 mm to 2 mm is illustrated, but the test is performed using the plurality of test samples having the hole diameter of less than 0.5 mm. Even when it is performed, the correlation between the hole diameter and the amplitude value can be obtained in almost the same manner, and even when the test is performed using the test sample having the hole diameter of more than 2.0 mm, The correlation with the amplitude value can be obtained in almost the same manner. Therefore, the hole formed in the inspection target component can be inspected even if the hole diameter is in the unit of μm, and can be inspected even if the hole diameter is a large diameter of 10 mm or more.

  (5) Although the sweep frequency for driving the speaker 110 is set to 1 Hz to 10 KHz in the first embodiment, the present invention is not limited to this and can be appropriately changed.

  (6) The shape and structure of the hole inspection device 10 used in each of the above-described first embodiments are not limited to those shown in FIG. 2, and various modifications can be made. Further, the size of the outer diameter when the component to be inspected is disc-shaped is not limited to one type, and it is possible to adopt a structure in which various outer diameters are to be inspected. Further, the shape of the inspection target component does not have to be circular, and it is possible to have a structure capable of inspecting various shapes, and it is also possible to inspect various thicknesses. It can be a structure.

  (7) In each of the above-described first embodiments, the case where the planar shape of the hole is circular (true circle) is illustrated, but the shape is not limited to circular. That is, since the hole inspection method and the hole inspection apparatus of the present invention perform the hole inspection based on an electric signal that depends on the flow rate of the fluid flowing through the hole formed in the inspection target component, for example, the inspection The shape of the hole of interest may be elliptical. Further, even if holes having various shapes such as a triangle, a square such as a quadrangle, and even a star shape, the suitability of the holes formed in the inspection target component with respect to the holes formed in the master sample is determined. be able to. In addition, when the hole is circular, the diameter of the front surface side of the inspection target component may be different from the diameter of the back surface side, and when the shape of the inspection target hole is a shape other than circular, The surface area and the back surface area of the target component may be different. Even in such a case, it is possible to determine the suitability of the hole formed in the inspection target component with respect to the hole formed in the master sample.

  (8) In the above-described embodiment, the case where the appropriateness of the hole diameter is inspected with the thickness of the inspection target component being constant has been described. However, the hole inspection method and the hole inspection apparatus of the present invention are the holes formed in the inspection target component. Since the hole is inspected based on an electric signal that depends on the flow rate of the fluid flowing through, it is possible to inspect not only the hole diameter but also the volume of the hole.

  10 ... Hole inspection device, 100 ... Housing, 101 ... Space part, 102 ... Opening, 105 ... Partition plate, 106 ... Bottom surface, 107 ... Component placement part, 108 ... Component pressing part, 110 ... Speaker, 120 ... Speaker driving part, 130 ... Microphone (standard microphone), 131 ... Sound input part, 140 ... Frequency analysis part, 150. ..Hole inspection part, 200 ... parts, 201 ... holes, f11, f21, f31 ... reference resonance frequency, L1 to L3 ... reference line, SP1 to SP6 ... sample (test sample ), S1 to S3, S10 to S30 ... Step

Claims (13)

A hole inspection method for inspecting holes formed in a component to be inspected, which allows passage of fluid or light,
A housing having a space portion inside, an opening on one surface, and a portion other than the opening sealed.
A speaker that is provided on the side opposite to the surface having the opening in the space formed in the housing and that outputs sound toward the side of the opening;
A speaker drive unit that sweeps a frequency in a predetermined range with respect to the speaker within a predetermined time,
The flow rate of the gas passing through the hole when the speaker driving section frequency-sweeps the speaker in a state where the speaker driving unit is installed at a predetermined position in the space and the part having the hole is placed so as to cover the opening. A microphone that outputs an electrical signal that depends on
Frequency analysis of the electric signal output from the microphone, to generate a resonance frequency spectrum in which the resonance frequency exists,
Based on the resonance frequency spectrum generated by the frequency analysis unit, a hole inspection unit for inspecting the size of the hole,
A hole inspection method for inspecting the hole using a hole inspection device comprising:
A master sample is formed with holes that are confirmed to be able to pass a predetermined amount of fluid or light, and a hole having a size different from the size of the holes formed in the master sample is formed, and A plurality of samples that are confirmed to be able to pass a predetermined amount of fluid or light is used, and the opening of the housing is sequentially covered for each sample including the master sample and the plurality of samples. And the frequency sweeping of the speaker,
Frequency-analyzing the electric signal output from the microphone to generate a resonance frequency spectrum for each sample;
Obtaining a correlation between the spectral components contained in the resonance frequency spectrum of each sample and the size of the hole formed in each sample,
A step of sweeping the frequency of the speaker with the inspection target component placed so as to cover the opening;
Frequency-analyzing the electric signal output from the microphone to generate an inspection target resonance frequency spectrum corresponding to the inspection target component;
Based on the spectrum component contained in the inspection target resonance frequency spectrum and "the correlation between the spectrum component contained in the resonance frequency spectrum of each of the samples and the size of the hole formed in each sample" A step of inspecting a size of a hole formed in the inspection target component,
A hole inspection method comprising: The hole inspection method according to claim 1,
The electric signal output from the microphone is a sine wave signal,
The hole inspection method, wherein the frequency analysis unit generates a resonance frequency spectrum for each sample and the inspection target resonance frequency spectrum by performing a fast Fourier transform on the sine wave signal. The hole inspection method according to claim 1 or 2,
The master sample is a sample for determining the suitability of the size of the hole formed in the inspection target component,
The step of inspecting the size of the hole is based on the spectral components included in the resonance frequency spectrum of the master sample among the resonance frequency spectra of each sample and the spectral components included in the resonance frequency spectrum to be inspected. A hole inspection method, comprising determining whether or not the size of a hole formed in the inspection target component is appropriate. The hole inspection method according to claim 3,
The spectral component is an amplitude value,
When the resonance frequency existing in the resonance frequency spectrum of the master sample is the reference resonance frequency, and the amplitude value of the reference resonance frequency is the reference amplitude value,
"Correlation between the components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" is,
It is a correlation between the amplitude value of each resonance frequency spectrum of each sample at the reference resonance frequency and the size of the hole formed in each sample,
The step of determining the suitability of the size of the hole is based on the reference amplitude value and the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency, and the suitability of the size of the hole formed in the inspection target part. A hole inspection method characterized by determining. The hole inspection method according to claim 4,
The reference amplitude value, the allowable range for determining the suitability of the size of the hole formed in the inspection target component is set,
The step of determining suitability of the size of the hole is formed in the inspection target component by determining whether the amplitude value of the inspection target resonance frequency spectrum at the reference resonance frequency is within the allowable range. A hole inspection method, comprising: determining whether the size of a hole being formed is appropriate. The hole inspection method according to claim 4 or 5,
In each frequency analysis result obtained corresponding to each sample, when the first to nth (n is a natural number) resonance frequency spectrum is generated for each sample,
Of the first to nth (n is a natural number) resonance frequency spectra for each sample, use is made of a resonance frequency spectrum in which a large difference in amplitude value of each resonance frequency spectrum of each sample at the reference resonance frequency is obtained. A hole inspection method characterized by. The hole inspection method according to claim 3,
The spectral component is an amplitude value,
"Correlation between the spectral components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" is,
The amplitude value of each resonance frequency present in each resonance frequency spectrum of each sample is a correlation between the size of the holes formed in each sample including the master sample,
When the amplitude value of the resonance frequency existing in the resonance frequency spectrum of the master sample and the reference amplitude value,
The step of determining the suitability of the size of the hole is based on the reference amplitude value and the amplitude value of the resonance frequency existing in the resonance frequency spectrum of the inspection target, and the suitability of the size of the hole formed in the inspection target component. A hole inspection method characterized by determining. The hole inspection method according to claim 7,
The reference amplitude value, the allowable range for determining the suitability of the size of the hole is set,
The step of determining the suitability of the size of the hole is formed on the inspection target component by determining whether or not the amplitude value of the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range. A hole inspection method, characterized by determining whether or not the size of a hole being formed is appropriate. The hole inspection method according to claim 3,
The spectral component is a resonant frequency,
"Correlation between the spectral components included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample" is,
It is a correlation between the resonance frequency present in each resonance frequency spectrum of each sample and the size of the hole formed in each sample including the master sample,
When the resonance frequency existing in the resonance frequency spectrum of the master sample is the reference resonance frequency,
The step of determining the suitability of the size of the hole is to determine the suitability of the hole formed in the inspection target component based on the reference resonance frequency and the resonance frequency existing in the inspection target resonance frequency spectrum. Characteristic hole inspection method. The hole inspection method according to claim 9,
The reference resonance frequency, the allowable range for determining the suitability of the size of the hole is set,
The step of determining the suitability of the size of the hole is a hole formed in the inspection target component by determining whether the resonance frequency existing in the inspection target resonance frequency spectrum is within the allowable range. A hole inspection method characterized by determining suitability of the size of the hole. The hole inspection method according to any one of claims 1 to 10,
The master sample and the inspection target component have the same thickness,
The hole inspection method, wherein the inspection of the size of the hole is an inspection of the diameter of the hole. The hole inspection method according to any one of claims 1 to 11,
A plurality of the holes are provided in one inspection target component, and the plurality of holes can simultaneously pass the fluid or the light,
The hole inspection method, wherein the microphone outputs an electric signal depending on a flow rate of gas flowing through the plurality of holes at the same time. A hole inspection device for inspecting a hole formed in a component to be inspected, which allows passage of fluid or light,
A housing having a space portion inside, an opening on one surface, and a portion other than the opening sealed.
A speaker that is provided on the side opposite to the surface having the opening in the space formed in the housing and that outputs sound toward the side of the opening;
A speaker drive unit that sweeps a frequency in a predetermined range with respect to the speaker within a predetermined time,
The flow rate of the gas passing through the hole when the speaker driving section frequency-sweeps the speaker in a state where the speaker driving unit is installed at a predetermined position in the space and the part having the hole is placed so as to cover the opening. A microphone that outputs an electrical signal that depends on
Frequency analysis of the electric signal output from the microphone, to generate a resonance frequency spectrum in which the resonance frequency exists,
Based on the resonance frequency spectrum generated by the frequency analysis unit, a hole inspection unit for inspecting the size of the hole,
Equipped with
The frequency analysis unit includes a master sample in which holes that are confirmed to be able to pass a predetermined amount of fluid or light are formed, and a hole having a size different from the size of the holes formed in the master sample. And a plurality of samples for which fluid or light has been confirmed to be able to pass in a predetermined amount are placed on the speaker so as to cover the opening of the housing in order. When the frequency is swept, the spectrum components included in the resonance frequency spectrum of each sample including the master sample and the plurality of samples obtained by frequency-analyzing the electric signal output from the microphone and the respective It has the function of finding the correlation with the size of the holes formed in the sample,
The hole inspection unit is an inspection object obtained by frequency-analyzing an electric signal output from the microphone when the speaker is frequency-swept in a state where the inspection object component is placed so as to cover the opening. The component to be inspected based on the spectrum component included in the resonance frequency spectrum and "the correlation between the spectrum component included in the resonance frequency spectrum of each sample and the size of the hole formed in each sample". A hole inspection apparatus having a function of inspecting a size of a hole formed in the hole.