JP5715516B2 - Fine hole inspection apparatus and fine hole inspection method - Google Patents

Description

  The present invention relates to a micropore inspection apparatus and a micropore inspection method for inspecting micropores.

  Parts in which fine holes are formed are used in a wide range of fields. For example, in a gas sensor that detects a specific gas, such as a CO gas sensor, a component in which fine holes are formed is used.

  FIG. 11 is a view for explaining the CO gas sensor 900. 11A is a sectional view schematically showing the internal structure of the CO gas sensor 900, and FIG. 11B is an enlarged view showing the diffusion control plate 923 used in the CO gas sensor 900. It is a perspective view.

  As shown in FIG. 11, the CO gas sensor 900 includes a cylindrical casing 910 made of a conductive member, and a gas sensing unit 920 provided on one end side (the upper end side) of the casing 910. doing.

  The housing 910 has a space inside, and a predetermined amount of distilled water 930 is stored in the space. The gas sensing unit 920 includes a sensor cap 922 in which an activated carbon filter 921 is filled, a diffusion control plate 923 made of a member having a predetermined rigidity such as stainless steel, and a film sandwiched between two packing layers 924. -It has the electrode assembly, 925, and the washer 926 which consists of stainless steel etc., and these are in the state laminated | stacked. The activated carbon filter 921 is for reducing the sensitivity to miscellaneous gases other than the CO gas to be detected.

  The sensor cap 922 is formed with a gas intake hole 922a for taking in the gas. For example, when CO gas exists in the atmosphere for some reason, the CO gas enters the CO gas sensor 900 from the gas intake hole 922a. It has become. In addition, a fluid circulation hole 927 is provided on the lower end side of the sensor cap 922, and a fluid circulation hole 928 is also provided in the washer 926.

  The diffusion control plate 923 has a disk shape with an outer diameter of about 8.5 mm and a thickness of about 100 μm, and a fine hole 929 is provided at the center. The diffusion control plate 923 having such a configuration has a function for sending CO gas from the atmosphere into the membrane-electrode assembly 925 and diffusion of water vapor generated by distilled water 930 stored in the housing 910. It has a function to control. For this reason, the fine hole 929 formed in the diffusion control plate 923 is required to have high accuracy, and the accuracy greatly affects the performance as the CO gas sensor.

  The CO gas sensor 900 configured in this manner is in a state where the membrane-electrode assembly 925 is always wet by water vapor generated from distilled water, and in this state, CO gas enters the sensor cap 922 from the gas intake hole 922a. Then, the CO gas passes through the fluid flow hole 927 provided in the lower end surface of the sensor cap 922, and further passes through the fine hole 929 formed in the diffusion control plate 923. To reach. A minute current flows due to a chemical reaction between water and CO contained in the membrane-electrode assembly 925, and the current is output.

  Such a CO gas sensor 900 is mounted on a CO gas detection device (not shown), so that the CO gas detection device has a CO gas detection function. That is, by mounting the CO gas sensor 900 as shown in FIG. 11 in the CO gas detection device, when a current output from the CO gas sensor 900 reaches a predetermined value, a constant concentration of CO gas is detected. Therefore, it is possible to perform operations such as generating an alarm sound and automatically stopping the gas supply.

  A CO gas detection apparatus equipped with such a CO gas sensor 900 needs to perform a highly accurate gas detection operation because the CO gas to be measured has a serious adverse effect on the human body. For this reason, the fine holes 929 formed in the diffusion control plate 923 of the CO gas sensor 900 are required to have high accuracy. For example, if the hole diameter appropriate for the fine hole 929 is 100 μm, the tolerance of the hole diameter of the fine hole 929 is required to have a high accuracy of “100 μm ± 5 μm”. Therefore, when manufacturing the diffusion control plate 923 in which such high-precision fine holes 929 are formed, the suitability of the fine holes 929 formed by pressing or the like, that is, the hole diameter of the fine holes 929 is the above-described allowable value. It is necessary to check whether it falls within the range.

  In order to inspect the suitability of the fine hole 929, it is generally performed to measure the hole diameter and determine the suitability of the fine hole 929 based on the measurement result. Various apparatuses for measuring the hole diameter of the fine holes 929 have existed conventionally (see, for example, Patent Document 1).

  The hole diameter measuring device disclosed in Patent Document 1 (hereinafter referred to as a conventional hole diameter measuring device) is a device that measures the hole diameter of a die having fine holes, but from the viewpoint of measuring the hole diameter of fine holes, This is common with the measurement of the diameter of the fine holes 929 formed in the diffusion control plate 923. A conventional hole diameter measuring apparatus acquires a hole of a die as an enlarged image of a microscope, and measures the hole diameter by performing image processing on the acquired enlarged image.

JP-A-6-294619

  The conventional hole diameter measuring apparatus needs to perform a process of acquiring an enlarged image of a microscope, performing image processing on the acquired enlarged image and measuring the hole diameter, and thus has a problem that it takes time for measurement. Particularly, in the diffusion control plate 923 used in the CO gas sensor 900, since it is necessary to inspect all the diffusion control plates 923, it is required and possible to measure each diffusion control plate in a short time. For example, it is required to determine the suitability by measuring the hole diameter in the flow of the manufacturing process of the diffusion control plate.

  On the other hand, even if a highly accurate hole diameter can be measured by the above-described conventional hole diameter measuring apparatus, there is a further problem in using it as the diffusion control plate 923 used in the CO gas sensor 900. That is, when the fine holes are formed by, for example, pressing, burrs often occur in the punching direction. For this reason, there are many cases in which the hole diameters of the micro holes are different between the front side and the back side of the component, and burrs may exist not only in the punching direction but also in the micro holes.

  If there are burrs in the punching direction and the hole diameters of the fine holes 929 are different between the front side and the back side of the diffusion control plate 923, the front side hole diameter (referred to as the front hole diameter) and the back side hole diameter (referred to as the back hole diameter). ) And a long time for the measurement. In this case, if either the front hole diameter or the back hole diameter is out of the allowable range, it is necessary to determine that the micropore is incompatible at that stage, and the diffusion control plate 923 is incompatible with the noncompliant product (NG Product). For this reason, the yield in the manufacturing process of the diffusion control plate 923 is poor, and there is a problem that the production efficiency is lowered.

  However, even if either the front hole diameter or the back hole diameter is slightly deviated, if the diffusion control plate is used as a diffusion control plate for the above-described CO gas sensor and the CO gas detection test is actually performed, an appropriate CO gas can be obtained. A detection operation may be performed. Such a diffusion control plate is also determined as an NG product as described above in the inspection of only the hole diameter.

  In addition, if burrs are present in the fine holes, it may not be possible to determine whether the fine holes 929 are really proper simply by measuring the surface hole diameter and the back hole diameter of the diffusion control plate. For example, even if the result of measuring the surface hole diameter and back hole diameter of the diffusion control plate is determined to be a conforming product, the diffusion control plate is actually incorporated into the CO gas sensor as described above, and the CO gas detection test is performed. When this is done, it is possible that a proper inspection could not be performed.

  Thus, when the hole diameter of the fine hole 929 is measured using a conventional hole diameter measuring apparatus and the fine hole 929 is inspected based on the measurement result, it is formed on each component (for example, a diffusion control plate). There is a problem that the microhole 929 that is present cannot be inspected in a short time, and the inspection is based only on the hole diameter, so that an inspection result that matches the actual situation cannot be obtained.

  Such a problem is not a problem that exists only when inspecting micropores of components used in a gas sensor such as a CO gas sensor, but a component in which micropores are formed (for example, fuel injection for vehicle use). This is a problem that exists in almost all cases of inspecting microscopic holes in various parts such as nozzles and microphone filters.

  Therefore, an object of the present invention is to provide a fine hole inspection apparatus and a fine hole inspection method capable of performing an inspection in a short time and obtaining an inspection result in accordance with the actual situation.

  The inventor has scrutinized what kind of inspection should be performed in order to achieve the above-described object. As a result, it was found that the suitability of the fine holes 929 can be better determined by judging the volume of the fine holes 929 than judging by the diameter of the fine holes 929. As an example, when the component in which the micro holes are formed is the diffusion control plate of the CO gas sensor as described above, either the surface hole diameter or the back hole diameter of the micro holes is slightly less than the allowable range as described above. Even when the diffusion control plate is incorporated in the CO gas sensor, a proper detection operation may be performed when the CO gas detection test is performed. This is because an appropriate detection operation is performed if the volume of the micropores is an appropriate volume.

  From this, it is possible to obtain better results by judging the suitability of the micropores by the volume of the micropores than by judging the pore diameter of the micropores. In addition, the volume of a micropore can be represented with the flow volume when a fluid is poured into a micropore. For this reason, it is possible to acquire a parameter based on the flow rate of the fluid flowing through the micropore and determine whether the micropore is appropriate based on the acquired parameter. However, the method of flowing a liquid or gas as a fluid and measuring the flow rate has a problem that a large amount of time is spent on large-scale equipment and measurement. Therefore, as a result of various experiments, the present inventor has confirmed that a parameter representing the flow rate of fluid can be obtained by using acoustic technology, and has completed the present invention.

  [1] That is, the microscopic hole inspection apparatus of the present invention is a microscopic hole inspection apparatus for inspecting microscopic holes formed in a component, and includes a substantially hermetically sealed casing having a space portion therein, and the casing Installed on one end surface side of the speaker, and outputs a low-frequency sound by a low-frequency signal, and outputs a predetermined electrical signal by vibrating the diaphragm in response to the low-frequency sound output by the speaker The microphone is provided on the side opposite to the one end surface in the housing, and has a microphone mounting surface for mounting the microphone so as to face the speaker, and the surface on the opposite side to the microphone mounting surface. An air passage that has a component placement surface on which the component is placed and that allows air vibration generated by the vibration of the diaphragm to pass to the component placement surface side. A low-frequency sound from the speaker in a state where the component is placed on the component placement surface so that the minute hole formed in the component communicates with the air passage hole. By outputting, a signal depending on a flow rate of air when the air passing through the air passage hole from the microphone passes through the fine hole is outputted as the electric signal.

  According to the micropore inspection device of the present invention, rather than performing determination of the suitability of micropores by the hole diameter, a parameter representing the volume of micropores, that is, the flow rate of the fluid is acquired as an electrical signal, The suitability of the fine holes is determined. Further, in the micropore inspection apparatus of the present invention, a parameter representing the volume of micropores, that is, the flow rate of fluid, is acquired as an electrical signal by using an acoustic technique using a speaker and a microphone. For this reason, an inspection can be performed in a short time without requiring a large-scale apparatus. The electric signal is, for example, a voltage value.

  As described above, according to the micropore inspection device of the present invention, the suitability of the micropores is determined based on the parameter representing the volume of the micropores, that is, the flow rate of the fluid. Even if there is a burr or a burr has occurred, it is possible to obtain a test result that matches the actual situation.

  In this specification, the low frequency sound means a sound in the range of 1 Hz to 100 KHz, but the low frequency used in the present invention is preferably set to 1 Hz to 150 Hz, more preferably. 1 Hz to 20 Hz.

  [2] In the microscopic hole inspection apparatus of the present invention, the speaker is installed such that a second space portion is formed between the back side of the speaker and one end surface in the housing, and It is preferable that a communication hole for communicating a part of the second space portion with the outside of the housing is formed in the housing.

  By adopting such a structure, the movement of the diaphragm of the speaker becomes more active, and a louder sound can be generated. As a result, the electrical signal can be output with high resolution, and therefore the determination of the suitability of the micropores can be performed with higher accuracy.

  [3] The microscopic hole inspection apparatus of the present invention preferably further includes an electrical signal display unit that displays the value of the electrical signal output from the microphone.

  By adopting such a configuration, it is possible to determine the suitability of the micropores based on the numerical values displayed on the electric signal display unit, and it is possible to easily and appropriately judge the suitability of the micropores.

  [4] In the micropore inspection apparatus of the present invention, the component is a component used in a gas sensor for detecting a specific gas, and the micropore formed in the component has a gas flow rate. In order to keep it constant, it is preferably used as a gas passage hole.

  This assumes that the part is used as, for example, a diffusion control plate of a gas sensor. In the gas sensor, is the amount of gas flowing through the micropores formed in the diffusion control plate appropriate? Whether or not it greatly affects the performance of the gas sensor. For this reason, the microscopic hole inspection apparatus of the present invention is optimal as an inspection apparatus for inspecting the microscopic holes formed in such a diffusion control plate.

  [5] In the micropore inspection device of the present invention, a plurality of types of parts in which micropores having different fluid flow rates are formed as samples, and the samples are attached to the gas sensor for each sample, It is preferable that a gas detection test for detecting a specific gas is performed by the gas sensor, and a value of an electric signal obtained by a sample when the gas sensor performs an appropriate gas detection operation is acquired in advance.

  As described above, the gas sensor associates the appropriate gas detection operation with the value of the electric signal (electric signal value) output from the microphone, so that the micropore can be easily obtained from the electric signal value obtained from the microphone. It is possible to determine whether or not it is appropriate. In addition, if there is an allowable range for the electric signal value when the appropriate detection operation is performed, it is possible to set the allowable range. In this case, the electric signal value output from the microphone is within the allowable range. If there is, it can be determined that the micropore is a conforming product.

  [6] In the micropore inspection apparatus of the present invention, it is preferable that the gas is a carbon monoxide gas and the gas sensor is a carbon monoxide gas sensor.

  In such a carbon monoxide gas sensor (referred to as a CO gas sensor) that detects carbon monoxide gas, since carbon monoxide (CO) gas has an adverse effect on the human body, components used in the CO gas sensor Is required to be accurate, and in particular, the fine holes formed in the diffusion control plate for maintaining a constant gas flow rate are required to be accurate. By inspecting the fine holes formed in such a diffusion control plate with the fine hole inspection apparatus of the present invention, the fine holes can be inspected appropriately. In addition, since the fine hole inspection apparatus of the invention can inspect individual fine holes at high speed, it is possible to inspect all the parts in which the fine holes are formed.

  [7] The microhole inspection method of the present invention is a microhole inspection method for inspecting microholes formed in a component, and outputs a low-frequency sound to one end face side in a substantially sealed casing. A partition member having an air passage hole is provided on the other end surface side of the housing, a surface of the partition member facing the speaker is a microphone mounting surface, and the microphone mounting surface is With the opposite surface as the component mounting surface, the microphone mounting surface is provided with a microphone that outputs a predetermined electrical signal by vibrating the diaphragm in response to the low frequency sound output by the speaker, With the component placed on the component placement surface of the partition member so that the minute hole formed in the component communicates with the air passage hole, By outputting the sound, characterized in that air passing through the air passage hole from the microphone to a flow-dependent signal of the air as it passes through the micropores so as to output as the electrical signal.

  Also in the fine hole inspection method of the present invention, the same effects as those of the fine hole inspection apparatus of the present invention described above can be obtained. In addition, also in the micropore inspection method of the present invention, it is preferable to have each feature of the micropore inspection device of the present invention described above.

It is a figure shown in order to demonstrate 100A of micro hole inspection apparatuses which concern on Embodiment 1. FIG. It is a figure which shows the list of the some sample used for the test. It is a figure which expands and shows the micropore of two samples of a press-work product by a laser microscope. It is a figure which expands and shows the micropore of two samples of nine types of samples of an electric discharge machining product with a laser microscope. It is a figure which shows the voltage value obtained in each sample shown in FIG. It is a figure shown in order to demonstrate that a voltage value is dependent on the volume (flow rate of fluid) of the fine hole 141. FIG. It is a figure which shows the voltage value obtained by the method of the mounting of the components 140 in case the surface hole diameter and back hole diameter of the micro hole 141 differ. It is a figure shown in order to demonstrate the resolution | decomposability of the voltage value which can be measured in 100 A of micropore inspection apparatuses which concern on Embodiment 1. FIG. It is a figure shown in order to demonstrate the micropore inspection apparatus 100B which concerns on Embodiment 2. FIG. It is a figure which compares and compares the voltage value with respect to the front-and-back average hole diameter in each sample of an electrical discharge machining product with respect to 100 A of micro hole inspection apparatuses which concern on Embodiment 1, and the micro hole inspection apparatus 100B which concerns on Embodiment 2. FIG. It is a figure shown in order to demonstrate the CO gas sensor 900. FIG.

  Hereinafter, embodiments of the present invention will be described.

[Embodiment 1]
1. Diagram 1 micropore inspection apparatus 100A according to Embodiment 1 is a view for explaining the micropore inspection apparatus 100A according to the first embodiment. 1A is a cross-sectional view schematically showing an internal configuration of the microscopic hole inspection apparatus 100A according to the first embodiment, and FIG. 1B is a microphone in the microscopic hole inspection apparatus 100A according to the first embodiment. It is a figure which expands and shows 130 and its peripheral part.

  As shown in FIG. 1, the microscopic hole inspection apparatus 100 </ b> A according to the first embodiment includes a substantially sealed cylindrical housing 110 having two space portions (described later) inside, and an inside of the housing 110. A speaker 120 that is installed on one end face side (referred to as the bottom face 112 side) and generates low-frequency sound toward the upper side inside the casing 110; A partition member 150 having a microphone 130 provided at an opposing position, a microphone mounting surface 150a for mounting the microphone 130, and a component placement surface 150b on which the component 140 in which the micro hole 141 is formed is placed; The role of pressing the component 140 when the component 140 is placed on the component placement surface 150b of the partition member 150 and the role of the lid of the housing 110 A lid 160 formed, a low-frequency oscillator 170 that applies a low-frequency signal to the speaker 120, and an electric signal display unit (an electronic voltmeter 180) that displays a value (voltage value) of an electric signal output from the microphone 130. ). The component 140 is assumed to be the same component as the diffusion control plate 923 used in the CO gas sensor 900 as shown in FIG.

  The speaker 120 is attached to the bottom surface 112 side in the housing 110. However, in the microscopic hole inspection apparatus 100A according to the first embodiment, the speaker 120 is not attached in contact with the bottom surface 112, but is predetermined from the bottom surface 112. The diaphragm 120a is attached so that the diaphragm 120a faces upward.

  In order to attach the speaker 120 to such a position, in the microscopic hole inspection apparatus 100A according to the first embodiment, the flange portion 113 is slightly above the bottom surface 112 of the housing 110 and the entire circumference of the inner side wall 114 of the housing 110. The speaker 120 is attached to the central portion of the flange portion 113.

  As a result, two spaces (a first space 111a and a second space 111b) are formed inside the housing 110. The first space 111 a is a space formed between the speaker 120 and the partition member 150. The second space portion 111 b is a space portion formed between the speaker 120 and the bottom surface 112 of the housing 110. The housing 110 is formed with a communication hole 115 for communicating the second space 111b with the outside of the housing 110. By forming such a second space portion 111b, the back side of the speaker 120 is opened. In addition, since the mounting position of the speaker 120 is slightly above the bottom surface 112 of the housing 110, the volume of the second space 111b is smaller than that of the first space 111a.

  For example, a dynamic microphone can be used as the microphone 130, and a diaphragm 132, a coil 133, a magnet 134, and the like are provided inside the microphone casing 131. In addition, the microphone housing 131 is provided with a plurality of sound input holes 131 a for taking in low-frequency sound emitted from the speaker 120.

  The microphone 130 configured in this manner is attached to the lower end surface (microphone attachment surface 150a) of the partition member 150 so as to face the speaker 120. Further, in the microphone 130, when the component 140 is placed on the upper end surface (component placement surface 150 b) of the partition member 150, the diaphragm 132 of the microphone 130 faces the component 140 through the partition member 150. Arrangement.

  The component 140 is assumed to have the same configuration as the diffusion control plate 923 shown in FIG. That is, it is made of stainless steel or the like, has a disk shape with an outer diameter of about 8.5 mm and a thickness of about 100 μm, and a fine hole (the fine hole 141 in the first embodiment) is formed at the center.

  The partition member 150 is formed with an air passage hole 151 having a slightly larger diameter than the fine hole 141 formed in the component 140. When the component 140 is placed at a predetermined position on the component placement surface 150 b of the partition member 150, the fine hole 141 formed in the component 140 and the air passage hole 151 formed in the partition member 150 communicate with each other. It is supposed to be. The partition member 150 is provided with a positioning portion 152 so that the component 140 can be placed at a predetermined position. This positioning part 152 may be, for example, a concave depression that matches the shape of the component 140. By providing such a positioning portion 152, when the component 140 is placed on the positioning portion 152, the fine holes 141 formed in the component 140 and the air passage holes 151 formed in the partition member 150 are automatically formed. Therefore, the positional relationship is appropriate.

  The lid body 160 has a circular hole 161 having a diameter slightly smaller than the outer diameter (about 8.5 mm) of the component 140 at the center thereof. Thus, when the lid 160 holds the component 140, only the peripheral edge of the component 140 is pressed.

  The low frequency oscillator 170 oscillates a low frequency signal of 11 Hz in the micropore inspection apparatus 100A according to the first embodiment. Thereby, the speaker 120 emits a low frequency sound of 11 Hz. Note that it is preferable that the speaker 120 emit a sound having a frequency as low as possible. In the microscopic hole inspection apparatus 100A according to the first embodiment, the reason why the low frequency sound of 11 Hz is used is because the lower limit value is in the characteristics of the speaker 120 and the microphone 130 used in the microscopic hole inspection apparatus 100A according to the first embodiment. is there.

  The microphone 130 is preferably a high resolution type. Specifically, the microphone 130 is configured using lightweight and highly sensitive parts (diaphragm, coil, magnet, etc.) used for audio earphones. Thereby, the microphone 130 was able to capture the 11 Hz low frequency sound output from the speaker 120.

  The electronic voltmeter 180 displays the voltage value (mV) output from the microphone 130 when the low frequency sound emitted from the speaker 120 is captured by the microphone.

2. Method for Inspecting Micro Hole 141 Using Micro Hole Inspection Apparatus 100A According to Embodiment 1 Next, a method for inspecting micro hole 141 for inspecting micro hole 141 using micro hole inspection apparatus 100A according to Embodiment 1 will be described. . First, the component 140 in which the fine hole 141 is formed is placed on the positioning portion 152 of the component placement surface 150b. In this way, by placing the component 140 on the positioning portion 152 of the component placement surface 150b, the air passage hole 151 and the fine hole 141 of the partition member 150 are in communication with each other.

  In this state, when a low frequency sound of 11 Hz is oscillated from the speaker 120, the low frequency sound is transmitted to the microphone 130 as air vibration, and the diaphragm 132 provided in the microphone 130 vibrates, and the coil 133 and Electromagnetic induction by the magnet 134 occurs, and a voltage value generated by the electromagnetic induction is displayed on the voltmeter 180.

  At this time, the vibration of the air due to the vibration of the diaphragm 132 of the microphone 130 passes through the fine hole 141 from the air passage hole 151 of the partition member 150 and goes out of the housing 110. At this time, the amount of air passing through the fine hole 141 affects the voltage output from the microphone 130, and a minute change occurs in the voltage value output from the microphone 130. In other words, the voltage value output from the microphone 130 is affected by the amount of air passing through the fine hole 141 and slightly changes.

  That is, depending on the volume of the micropore 141, that is, the flow rate of the fluid, the amount of air passing through the micropore 141 changes, thereby causing a minute change in the voltage output from the microphone 130 and the voltmeter 180. The voltage value displayed on will change. In other words, the change in the voltage value displayed on the voltmeter 180 represents the change in the volume of the fine hole 141, that is, the flow rate of the fluid.

  From this, the volume of the fine hole 141, that is, the flow rate of the fluid can be obtained based on the voltage value displayed on the voltmeter 180. Therefore, depending on the type of the device on which the component 140 is mounted, the voltage value displayed on the voltmeter 180 is correlated with the operation performed by the device on which the component 140 is mounted. Appropriateness of the fine holes 141 formed in the component 140 can be determined from the displayed voltage value.

  For example, when the component 140 is the diffusion control plate 923 of the CO gas sensor 900 (see FIG. 11) as described above, the voltage value displayed on the voltmeter 180 and the CO gas detection operation of the CO gas sensor 900 are displayed. The voltage value when an appropriate CO gas detection operation is performed is obtained by repeatedly performing a test for obtaining a correlation with. In this case, if there is an allowable range for the voltage value when an appropriate CO gas detection operation is performed, the allowable range is set. Thereby, when inspecting the fine hole 141 formed in each component 140, the suitability of the fine hole 141 can be determined from the voltage value displayed on the voltmeter 180. In this case, the voltage value is a value depending on the volume of the fine hole 141, that is, the flow rate of the fluid, so even if there is a difference in the surface hole diameter and the back hole diameter of the fine hole 141, Sometimes it is done. For this reason, the yield in the manufacturing process of components can be improved compared with the case where suitability is determined by the hole diameter.

  In addition, in the case where burrs are present inside the fine hole 141, it is not possible to determine whether or not the fine hole 929 is really appropriate only by measuring the front side hole diameter and the back side hole diameter of the part. In some cases, according to the microscopic hole inspection apparatus 100A according to the first embodiment, since the determination is made based on the volume of the microscopic hole 141, that is, the flow rate of the fluid, an appropriate inspection result in accordance with the actual situation can be obtained.

  In the microscopic hole inspection apparatus 100A according to the first embodiment, the components are sequentially placed on the component placement surface 150b and inspected in a state where low-frequency sound is constantly oscillated from the speaker 120. As a result, the components can be inspected one after another in the flow of the component manufacturing process.

3. Test Example Using Fine Hole Inspection Device 100A According to Embodiment 1 Next, a test example using the fine hole inspection device 100A according to Embodiment 1 will be described. Here, a test was performed in which a plurality of parts 140 in which the micro holes 141 were formed were prepared, and the micro holes 141 formed in each sample were inspected using the plurality of parts as samples.

  FIG. 2 is a diagram showing a list of a plurality of samples used in the test. Here, two parts actually manufactured by press working are used as samples, and in order to prepare parts having various hole diameters as test samples, parts having nine kinds of hole diameters are manufactured by electric discharge machining, respectively. Each of these nine types of hole diameters was used as a sample.

  In FIG. 2, the two parts actually manufactured by the press-processed product are manufactured by setting the target value of the hole diameter of the fine hole 141 to 105 μm, and the hole diameter of each fine hole 141 formed in the two parts is As a result of determining the suitability based on the result, a part determined to be a conforming product is an OK sample, and as a result of determining the suitability based on the hole diameter of the fine holes 141, a part regarded as a nonconforming product is an NG sample. In FIG. 2, the front hole diameter d1, the back hole diameter d2, the front hole diameter d1, and the front and back average hole diameters of the fine holes 141 formed in the OK sample and the NG sample are shown. The front and back average hole diameter is the average of the front hole diameter d1 and the back hole diameter d2.

  On the other hand, the samples having the nine types of hole diameters of the electric discharge machined products are manufactured by setting the target values of the fine holes 141 to 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 95 μm, 100 μm, 105 μm, and 110 μm. Shows the front hole diameter d1, the back hole diameter d2, and the front and back average hole diameter of each micro hole 141 formed in each sump product. These nine types of samples are referred to as “50 μm sample”, “60 μm sample”, “70 μm sample”,..., “110 μm sample”.

  FIG. 3 is an enlarged view of the fine holes 141 of the two parts of the press-processed product using a laser microscope. 3A shows the fine holes 141 of the OK sample, and FIG. 3B shows the fine holes of the NG sample. In FIG. 3, black portions are the fine holes 141. 3A shows the fine hole 141 and its peripheral portion as a cross-section, and a burr B is formed below the punching direction by press working, so the surface hole diameter d1 And the back hole diameter d2 are different. Such burrs B are also generated in FIG.

  FIG. 4 is a diagram showing the micropores 141 of two samples out of nine types of samples of the electric discharge machined product enlarged by a laser microscope. FIG. 4A is a view showing the fine hole 141 of the 50 μm sample, and FIG. 4B is a view showing the fine hole 141 of the 110 μm sample. In FIG. 4, black portions are the fine holes 141. 4A shows the fine hole 141 and its periphery as a cross-section. In this case, no burr is generated, but a taper is formed, so that the surface hole diameter d1 is shown. And the back hole diameter d2 are different.

  Here, for two samples of pressed products (OK sample, NG sample), if the fine holes 141 are judged appropriate based on the hole diameter, for example, if the allowable range for the target value of 105 μm is ± 5 μm, the OK sample The surface hole diameter (104.47 μm) and the back hole diameter (109.758 μm) both clear “105 μm ± 5 μm”. On the other hand, the surface hole diameter (104.368 μm) of the NG sample clears “105 μm ± 5 μm”, but the back hole diameter (111.424 μm) deviates from “105 μm ± 5 μm”. For this reason, the NG sample is regarded as a nonconforming product (NG product).

  FIG. 5 is a diagram showing voltage values obtained in the respective samples shown in FIG. In addition to the front hole diameter, the back hole diameter, and the front and back average diameter for each sample shown in FIG. 2, FIG. 5 shows a voltage value (mV) added to each sample.

  According to FIG. 5, the voltage value obtained in the OK sample of the pressed product was “1.41 mV”, and the voltage value obtained in the NG sample was also “1.41 mV”. Here, when a sample that outputs a voltage value of “1.41 mV” is used as a diffusion control plate of a CO gas sensor, it is confirmed by repeated CO gas detection tests that an appropriate CO gas detection operation is performed. If so, both the OK sample and the NG sample are determined to be conforming products. This is because the suitability of the fine holes 141 is not determined by the hole diameter, but by the volume of the fine holes 141 (fluid flow rate). That is, if the volume (flow rate of fluid) of the micropore 141 is an appropriate value, the micropore 141 performs an appropriate CO gas detection operation.

  As described above, since it is determined by the volume of the fine hole 141 (fluid flow rate) that even if the part is incompatible with the inspection by the hole diameter, it can be determined that the part is actually incompatible. The yield in the manufacturing process can be improved. Note that the NG sample in this case is a non-conforming product based on the hole diameter, but since it has been confirmed that an appropriate CO gas detection operation is performed, it can be determined that the product is a conforming product. There are no parts.

  FIG. 6 is a diagram for explaining that the voltage value depends on the volume (flow rate of fluid) of the fine hole 141. In FIG. 6, the horizontal axis represents the hole diameter of the micropore 141 in each sample shown in FIG. 5, the left vertical axis represents the front and back average hole diameter in FIG. 5, and the right vertical axis represents the voltage value.

  In FIG. 6, the press-processed product has a relationship between the front and back average hole diameters and the voltage values at the front and back average hole diameters for the OK sample and the NG sample. On the other hand, the electrical discharge machined product has a relationship between the front and back average hole diameters and the voltage values at the front and back average hole diameters of three samples of 110 μm sample, 105 μm sample, and 100 μm sample.

  Here, when considering a 105 μm sample of an electric discharge machined product having an average front and back average hole diameter of two samples (OK sample and NG sample) of the press processed product, voltage values of the OK sample and the NG sample of the press processed product are considered. Both are 1.41 m, and the voltage value of the 105 μm sample of the electric discharge machined product is 1.39 mV. When the front and back average pore diameters are close to each other, the voltage value is the same or very close. Since it can be said that the front and back average hole diameter of the fine hole 141 reflects the size of the volume of the fine hole 141, it can be seen that the voltage value depends on the volume of the fine hole.

  From this, the front hole diameter and the back hole diameter of the fine holes 141 are measured, the average hole diameter (front and back average hole diameter) is obtained, and the suitability of the fine holes can be determined based on the obtained front and back average hole diameters. However, in this case, it is necessary to perform many procedures such as obtaining the front and back average hole diameters after obtaining the front and back hole diameters for each fine hole. In some cases, it is difficult to accurately determine the hole diameter (back hole diameter). Moreover, the burr | flash may have arisen also in the micropore 141. For this reason, it is not a realistic method to determine the suitability of the micropores 141 simply based on the front and back average pore diameters.

  FIG. 7 is a diagram illustrating voltage values obtained depending on how the component 140 is placed when the surface hole diameter and the back hole diameter of the fine hole 141 are different. In FIG. 7, the horizontal axis represents two samples of pressed products (OK sample and NG sample) and nine types of samples of electric discharge processed products, and the vertical axis on the left represents the taper amount. In this case, the “taper amount” is a value obtained by “back hole diameter (μm) −front hole diameter (μm)”. The vertical axis on the right side is the difference in voltage value, that is, the voltage value obtained when the component is placed on the component placement surface 150b with the front side of the component facing upward, and the component placement surface 150b with the back side of the component facing upward. It represents the difference from the voltage value obtained in the case of setting.

  For example, in the NG sample of the press-processed product, the taper amount (the value obtained by subtracting the front hole diameter from the back hole diameter) is “111.424−104.368≈7” from FIG. 2 or FIG. A pore size difference exists. Thus, when there is a large hole diameter difference between the front and back surfaces, the voltage value obtained when the NG sample is placed on the component placement surface 150b of the partition member 150 with the front side facing upward, Taking the difference from the voltage value obtained when the NG sample is placed on the component placement surface 150b of the partition member 150 with the back side facing upward, the difference can be expressed as an absolute value. It is about 0.01 mV.

  In addition, the same applies to each sample of the electric discharge machined product. In this case, the taper amount (back hole diameter−front hole diameter) has a predetermined value for each sample. The difference was almost zero.

  Therefore, even if the component 140 is placed on the component placement surface 150b so that the front side faces upward, the voltage value obtained can be obtained even if the component 140 is placed on the component placement surface 150b so that the back side faces upward. It can be said that there is no big difference. This means that when parts are actually inspected, it is not necessary to be aware of the front and back of the parts 140 when placing individual parts on the part placement surface 150b of the partition member 150. As a result, the inspection speed can be increased.

  FIG. 8 is a diagram for explaining the resolution of voltage values that can be measured in the microscopic hole inspection apparatus 100A according to the first embodiment. In addition, in FIG. 8, the voltage value with respect to the front and back average hole diameter in each sample of an electric discharge machining product is shown. For example, the front and back average pore diameter of the 95 μm sample is 98.56 μm (see FIG. 2 or FIG. 5), and the voltage value obtained by the sample is 1.28 mV, and the front and back average pore diameter of the 100 μm sample is also shown. Is 102.27 μm (see FIG. 2 or FIG. 5), and the voltage value obtained by the sample is 1.34 mV, and the voltage value with respect to the front and back average pore diameter of each sample is shown.

  As can be seen from FIG. 8, when the front and back average pore diameter exceeds 90 μm, the degree of change in voltage value is particularly large. For example, the voltage value when the front and back average hole diameter is 98.56 μm is 1.28 mV. The voltage value when the front and back average hole diameter is 102.27 μm is 1.34 mV. The voltage value when the front and back average hole diameter is 106.466 μm is 1.39 mV. As described above, when the diameter of the micropores exceeds 90 μm, the degree of change in the voltage value increases, so that the resolution of the voltage value increases. In this case, when the front and back average hole diameter of the sample is 90 μm or more, the voltage value changes by approximately 0.1 mV when the front and back average hole diameter differs by 5 μm. Thereby, for example, it is possible to measure with high accuracy even a hole diameter whose tolerance is ± 5 μm with respect to a hole diameter of 100 μm.

  In the microscopic hole inspection apparatus 100A according to the first embodiment, in each sample prepared corresponding to various target hole diameters, a voltage value corresponding to each sample can be output. Therefore, the sample based on the voltage value It is possible to determine whether or not it is appropriate. In particular, when the target hole diameter is 90 μm or more, the voltage value can be output with high resolution, so that a more accurate inspection can be performed. In particular, when the component 140 is a diffusion control plate of a CO gas sensor, since a fine hole having a hole diameter of 100 μm or around that is often inspected, a more accurate inspection can be performed. In each sample prepared corresponding to a target hole diameter of less than 90 μm, a voltage value can be output with a certain resolution or more as shown in FIG. For this reason, the fine hole inspection apparatus 100A according to the first embodiment can be used as an inspection apparatus for fine holes having various hole diameters.

  In the microscopic hole inspection apparatus 100A according to the first embodiment, the result as shown in FIG. 8 is obtained because the structure of the housing 110 is as shown in FIG. That is, as shown in FIG. 1, by providing the space (second space 111b) on the back side of the speaker 120, the movement of the diaphragm 120a of the speaker 120 becomes more active and a louder sound can be generated. It is because it came to be. Further, by setting the frequency for driving the speaker 120 to a low frequency such as 11 Hz and making the microphone 130 high resolution, good results as shown in FIG. 8 were obtained.

[Embodiment 2]
FIG. 9 is a view for explaining the microscopic hole inspection apparatus 100B according to the second embodiment. FIG. 9 is a cross-sectional view schematically showing the internal configuration of the microscopic hole inspection apparatus 100B according to the second embodiment. The configuration of the microscopic hole inspection apparatus 100B according to the second embodiment is different from the configuration of the microscopic hole inspection apparatus 100A according to the first embodiment in the mounting position of the speaker 120. That is, in the microscopic hole inspection apparatus 100 </ b> B according to the second embodiment, the speaker 120 is installed in contact with the bottom surface 112 of the housing 110. In FIG. 9, the same components as those in FIG. 1 are denoted by the same reference numerals.

  In addition, since the inspection procedure in the microscopic hole inspection apparatus 100B according to the second embodiment is the same as that of the microscopic hole inspection apparatus 100A according to the first embodiment, the description thereof is omitted here.

  In the microscopic hole inspection apparatus 100B according to the second embodiment, since the speaker 120 is installed in contact with the bottom surface 112 of the housing 110, the structure is simpler than that of the microscopic hole inspection apparatus 100A according to the first embodiment. However, the resolution of the voltage value output from the microphone 130 is slightly inferior to that of the microscopic hole inspection apparatus 100A according to the first embodiment. However, similarly to the microscopic hole inspection apparatus 100A according to the first embodiment, the volume (fluid flow rate) of the microscopic hole 141 can be output as a voltage value, and the suitability of the microscopic hole 141 is determined based on the voltage value. Can do. Thereby, the objective that the test | inspection result according to the actual condition can be obtained and the test | inspection in a short time is possible like the micropore inspection apparatus 100A which concerns on Embodiment 1 can be achieved.

  FIG. 10 is a diagram showing the voltage value with respect to the front and back average hole diameter in each sample of the electric discharge machine product by comparing the fine hole inspection apparatus 100A according to the first embodiment and the fine hole inspection apparatus 100B according to the second embodiment. 10A and 10B, the change in the voltage value indicated by the solid line is the same as the change in the voltage value indicated in FIG. 8, and the change in the voltage value indicated by the broken line indicates the microhole inspection according to the second embodiment. The change of the voltage value obtained by the apparatus 100B is shown.

  In addition, in the microscopic hole inspection apparatus 100B according to the second embodiment, five types of samples, ie, 95 μm sample, 100 μm sample, 105 μm sample, and 110 μm sample, are used as electrical discharge machined samples, and 11 Hz and 110 Hz from the speaker 120. The two types of low-frequency sounds were generated and tested. The change in the voltage value indicated by the broken line in FIG. 10A shows a case where a low frequency sound of 11 Hz is generated from the speaker 120, and the change in the voltage value indicated by the broken line in FIG. The case where a frequency sound is generated is shown.

  10A and 10B, the voltage value display range (right vertical axis in FIGS. 10A and 10B) in the microscopic hole inspection apparatus 100B according to the second embodiment is as follows. The voltage value is displayed as 0.7 mV in accordance with the display range of the voltage value in the case of the microscopic hole inspection apparatus 100A according to the first embodiment.

  In the microscopic hole inspection apparatus 100B according to the second embodiment, a test was performed using five types of samples, ie, a 100 μm sample, a 105 μm sample, and a 110 μm sample, but as shown in FIGS. Compared with these five types of samples, the resolution of the output voltage value is slightly inferior to the fine hole inspection apparatus 100A according to the first embodiment, but the fine hole inspection apparatus 100B according to the first embodiment. Similarly to the fine hole inspection apparatus 100A according to the above, the volume (flow rate of fluid) of the fine hole 141 can be output as a voltage value, and the suitability of the fine hole 141 can be determined based on the voltage value. Thereby, the objective that the test | inspection result according to the actual condition can be obtained and the test | inspection in a short time is possible like the micropore inspection apparatus 100A which concerns on Embodiment 1 can be achieved.

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

  (1) In each of the above embodiments, the case of inspecting the microhole of the diffusion control plate as a component used for the CO gas sensor is exemplified. However, the microhole inspection apparatus of the present invention is, for example, an in-vehicle fuel injection It can be used as a micropore inspection device that inspects micropores formed in various parts such as nozzles and microphone filters.

  (2) In the first embodiment, the speaker 120 is driven with a low frequency signal of 11 Hz. However, the low frequency signal for driving the speaker 120 is not limited to 11 Hz. If the performance permits, a lower frequency sound may be generated from the speaker. If a voltage having a predetermined resolution can be taken out from the microphone, the frequency may be higher than 11 Hz.

  (3) In each of the above embodiments, the electric signal value output from the microphone 130 is a voltage value, but is not limited to a voltage value, and may be another electric signal value.

  (4) The shape and structure of the microscopic hole inspection apparatuses 100A and 100B used in the above embodiments are not limited to those shown in FIGS. 1 and 9, and various modifications can be made without departing from the scope of the present invention. It is.

  (5) In each of the above embodiments, the case where there is one fine hole formed in one component is exemplified, but the present invention can also be applied to the case where a plurality of fine holes exist in one component. . Moreover, although the case where the cross-sectional shape of the fine hole is a circle (perfect circle) has been illustrated, it is not limited to a circle, and may be an ellipse, for example.

  100A, 100B ... Micropore inspection device, 110 ... Housing, 111a ... First space, 111b ... Second space, 112 ... Bottom surface, 113 ... Gutter, 114 ...... Inner side wall, 115 ... Communication hole, 120 ... Speaker, 120a ... Diaphragm, 130 ... Microphone, 131 ... Microphone housing, 132 ... Diaphragm, 133 ... Coil, 134 ... Magnet, 140 ... Part, 141 ... Micro hole, 150 ... Partition member, 150a ... Microphone mounting surface, 150b ... Part placement surface, 151 ... Air passage hole, 152 ... Positioning part, 160 ... Lid, 170 ... Low frequency oscillator, 180 ... Electronic voltmeter

Claims (7)

A fine hole inspection device for inspecting fine holes formed in a component,
A substantially sealed casing having a space inside, and
A speaker that is installed on one end surface side inside the housing and outputs low-frequency sound by a low-frequency signal;
A microphone that outputs a predetermined electrical signal by vibrating a diaphragm in response to low-frequency sound output from the speaker;
The microphone has a microphone mounting surface that is provided on the opposite side to the one end surface in the housing and mounts the microphone so as to face the speaker, and the component is mounted on a surface opposite to the microphone mounting surface. A partition member having a component placement surface to be placed and having an air passage hole for allowing air vibration generated by vibration of the diaphragm to pass to the component placement surface side;
Have
In a state where the component is placed on the component placement surface so that the micro hole formed in the component communicates with the air passage hole, low frequency sound is output from the speaker, so that the microphone A fine hole inspection apparatus characterized in that a signal depending on a flow rate of air when the air that has passed through the air passage hole passes through the fine hole is output as the electrical signal. In the micropore inspection apparatus according to claim 1,
The speaker is installed such that a second space portion is formed between a rear surface side of the speaker and one end surface inside the housing, and a part of the second space portion is disposed on the housing. A microhole inspection apparatus, wherein a communication hole for communicating with the outside is formed in the housing. In the micropore inspection apparatus according to claim 1 or 2,
The micropore inspection apparatus further comprising an electrical signal display unit that displays a value of an electrical signal output from the microphone. In the micropore inspection apparatus in any one of Claims 1-3,
The component is a component used in a gas sensor for detecting a specific gas, and the fine hole formed in the component is used as a gas passage hole in order to keep the gas flow rate constant. A micropore inspection device. In the micropore inspection apparatus according to claim 4,
A gas detection test in which a plurality of types of parts having micropores having different fluid flow rates are used as samples, the samples are attached to the gas sensor for each sample, and a specific gas is detected by the gas sensor. And a value of an electric signal obtained by a sample when the gas sensor performs an appropriate gas detection operation is acquired in advance. In the micropore inspection apparatus according to claim 4 or 5,
The gas is carbon monoxide gas, and the gas sensor is a carbon monoxide gas sensor. A fine hole inspection method for inspecting fine holes formed in a component,
While installing a speaker that outputs low frequency sound on the side of one end surface inside the substantially sealed casing, a partition member having an air passage hole is provided on the other end side of the casing,
The surface of the partition member facing the speaker is a microphone mounting surface, the surface opposite to the microphone mounting surface is a component placement surface, and the microphone mounting surface has low frequency sound output by the speaker. A microphone that outputs a predetermined electrical signal by vibrating the diaphragm in response to
By outputting the low frequency sound from the speaker in a state where the component is placed on the component placement surface of the partition member so that the micro hole formed in the component communicates with the air passage hole, A method for inspecting micropores, characterized in that a signal depending on a flow rate of air when the air that has passed through the air holes from the microphone passes through the micropores is output as the electrical signal.