JP2013036989A - Method and device for inspecting defect in honeycomb filter, and method for manufacturing honeycomb filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for inspecting, enabling a sufficiently accurate inspection even for a honeycomb filter with a relatively large size, and a method for manufacturing a honeycomb filter having a defect detection step by the method for inspecting.SOLUTION: A method for inspecting defects in a honeycomb filter 100 includes: a supply step in which a gas containing particle P is supplied to one end face 110b of the honeycomb filter 100; a first image acquisition step in which a first laser sheet LS, which spreads out along the other end face 100t of the honeycomb filter 100, is irradiated on gas discharged from the other end face 100t, and a first image containing an area facing the one end face of the honeycomb filter 100 in the first laser sheet LS is acquired; and a second image acquisition step in which the same process is performed with the first image acquisition step, except that a second laser sheet LS is irradiated from a direction different from that of the first laser sheet.

Description

  TECHNICAL FIELD The present invention relates to a honeycomb filter defect inspection method and inspection apparatus, and a honeycomb filter manufacturing method.

  Conventionally, a defect inspection method for a honeycomb filter used as a diesel particulate filter is known. For example, Patent Literature 1 discloses that a gas flow containing particles is provided on the inlet end face of a honeycomb filter, and the gas flow emitted from the outlet end face of the honeycomb filter is irradiated with a laser to illuminate the particles. In FIG. 2A of Patent Document 1, a planar light sheet 606 is irradiated on a gas flow in cooperation with an optical element such as a rotating polygon mirror 608.

JP 2009-503508 A

  However, in the conventional method, the inspection accuracy is not sufficient. In particular, when a honeycomb filter having a relatively large size (for example, a diameter of 70 mm or more) is an inspection target, there is a tendency to detect a defect erroneously even though there is no defect, and there is room for improvement. .

  An object of the present invention is to provide an inspection method and an inspection apparatus capable of performing inspection with sufficiently high accuracy even with a honeycomb filter having a relatively large size. Another object of the present invention is to provide a method for manufacturing a honeycomb filter including a defect detection step by the inspection method.

The honeycomb filter defect inspection method according to the present invention,
Supplying a gas containing particles to one end face of the honeycomb filter;
A first image acquisition step of acquiring a first image including the other end surface of the honeycomb filter in a state where the gas discharged from the other end surface of the honeycomb filter is irradiated with the first laser sheet that spreads along the other end surface. When,
After the first detection step, under the condition that the gas discharged from the other end face of the honeycomb filter is irradiated with a second laser sheet that extends along the other end face in a direction different from that of the first laser sheet, A second image acquisition step of acquiring a second image including the other end face of the filter.

  According to the observations of the present inventors, when laser light is irradiated along the end face of the honeycomb filter having a relatively large size, the peripheral part of the end face of the honeycomb filter and the part away from the light source of the laser light shines brightly. Even though there is no defect, a defect may be detected by mistake. The main reason for such excessive detection is that the present inventors scatter laser light by particles existing above the end face of the honeycomb filter, and the gas containing the particles serves as a light source to illuminate the peripheral portion of the honeycomb filter. I guess that. In the conventional inspection method, the inspection is performed by irradiating the laser beam from one place. The irradiated laser light is likely to diffuse when the distance to the irradiation target is increased, and more easily diffused particularly when irradiated with a gas containing particles. Therefore, as the size of the honeycomb filter (size of the end face) increases, Inspection accuracy at a location away from the laser light source is insufficient.

  In response to the above-described problem, a laser sheet that spreads along the other end face of the honeycomb filter is irradiated from two or more directions to detect the concentration distribution of particles in the gas. Of the concentration distribution data obtained from the laser sheets in each direction, the data of the locations where the distance from the light source of the laser sheet is close is adopted, and these are synthesized by a computer to obtain highly accurate concentration distribution data as a whole. can get. Note that it is not always necessary to synthesize data by a computer, and a defect portion may be specified by visually observing a plurality of image data.

In order to irradiate the honeycomb sheet with the laser sheet from two or more directions, for example, an inspection apparatus having two or more laser sheet light sources is prepared, and the detection process is performed by sequentially irradiating the laser sheets from these light sources. Just do it. That is, after the first detection step is performed by irradiating the first laser sheet from the first light source, the second laser sheet is irradiated from the second light source that is different from the first light source in the direction with respect to the honeycomb filter. Two detection steps may be performed. Alternatively, an inspection apparatus having a mechanism for rotating the honeycomb filter may be prepared, the first detection process may be performed, and then the honeycomb filter may be rotated to perform the second detection process. That is, after performing the first detection step by irradiating the first laser sheet from the light source, the orientation of the second laser sheet from the light source with respect to the honeycomb filter is different from the orientation of the first laser sheet in the first detection step. The second detection step may be performed by rotating the honeycomb filter so that the laser sheet is irradiated from the light source.
That is, the first laser sheet can be irradiated from the first light source, and the second laser sheet can be irradiated from a second light source different from the first light source.
In addition, the first laser sheet and the second laser sheet are irradiated from one light source, and the above method is further performed after the first image acquisition step so that the direction of the second laser sheet is different from the direction of the first laser sheet. A step of rotating the honeycomb filter may be provided before the second image acquisition step.
In addition, the method may further include a determination step of determining whether or not there is a defect in the honeycomb filter based on the first image and the second image.
In the determination step, a first portion close to the light source of the laser sheet in the first image is extracted, a second portion close to the light source of the laser sheet in the second image is extracted, and the first portion and the second portion The presence or absence of defects in the honeycomb filter can be determined based on the above.
A second invention is a method for inspecting a defect of a honeycomb filter, the supply step of supplying a gas containing particles to one end face of the honeycomb filter,
The first laser sheet that spreads along the other end surface and the second laser sheet that spreads along the other end surface of the gas discharged from the other end surface of the honeycomb filter are oriented in the direction of the first laser sheet and the first laser sheet. An image acquisition step of acquiring an image including the other end face of the honeycomb filter under a state where the two laser sheets are irradiated in different directions.
According to this method, since the particles discharged from the gas leaking portion scatter two different laser sheets, the brightness of the particles discharged from the gas leaking portion becomes very strong, so that the accuracy can be increased.

  In order to perform inspection with sufficiently high accuracy, the angle formed by the direction of the first laser sheet and the direction of the second laser sheet is preferably 160 to 200 °.

  In the present invention, the particles may be generated by supplying a liquid and a gas to a two-fluid nozzle, or the particles may be generated by mixing water and dry ice. The partition walls of the honeycomb filter are preferably porous.

One aspect of the inspection device for defects of the honeycomb filter according to the present invention,
A holding part for holding the honeycomb filter;
A supply path for supplying a gas containing particles to one end face of the honeycomb filter;
A first light source that irradiates a first laser sheet that spreads along the other end surface toward the gas discharged from the other end surface of the honeycomb filter;
A second light source that irradiates a first laser sheet that spreads along the other end face toward the gas discharged from the other end face of the honeycomb filter in a direction different from the first laser sheet;
A camera for acquiring an image including the other end face of the honeycomb filter.
Each of the above-described devices can further include a detection unit that detects the presence or absence of defects in the honeycomb filter based on a plurality of images acquired by the camera.

Another aspect of the inspection apparatus for defects of the honeycomb filter according to the present invention is as follows:
A rotating mechanism for holding the honeycomb filter and rotating the honeycomb filter about the central axis of the honeycomb filter;
A supply path for supplying a gas containing particles to one end face of the honeycomb filter;
A light source that irradiates a laser sheet that spreads along the other end surface toward the gas discharged from the other end surface of the honeycomb filter;
A camera for acquiring an image including the other end face of the honeycomb filter.

A method for manufacturing a honeycomb filter according to the present invention,
By the above inspection method, a detection step of detecting a defect of the honeycomb filter,
And a sorting step of sorting out the honeycomb filter in which no defect is detected in the detection step.

  According to the present invention, even a honeycomb filter having a relatively large size can be inspected with sufficiently high accuracy.

FIG. 1A is a perspective view of a honeycomb filter 100 to be inspected, and FIG. 1B is a view taken along the arrow Ib-Ib in FIG. FIG. 2 is a schematic cross-sectional view of a defect inspection apparatus 400 for the honeycomb filter 100. 3A is a top view showing a state where the laser sheet LS is irradiated from the first light source 210A, and FIG. 3B is a top view showing a state where the laser sheet LS is irradiated from the second light source 210B. FIG. 4A and 4B are diagrams schematically showing images obtained when the first and second light sources 210A and 210B are used, respectively, and FIG. 4C is a schematic diagram showing an image obtained by combining two image data. FIG. FIG. 5 is a schematic cross-sectional view of a defect inspection apparatus 500 for the honeycomb filter 100. 6A is a top view showing a state in which the laser sheet LS1 and the laser sheet LS2 are irradiated from the first light source 210A and the second light source 210A, and FIG. 6B is a process of FIG. 6A. It is a schematic diagram which shows the image obtained.

  An embodiment of the invention will be described with reference to the drawings. First, the honeycomb filter 100 to be inspected in the present embodiment will be described. The honeycomb filter 100 can be used as, for example, a diesel particulate filter.

  As shown in FIGS. 1A and 1B, the target honeycomb filter 100 in the present embodiment includes partition walls 112 that form a plurality of flow paths 110 that extend in parallel to each other, and a plurality of flow paths 110. A cylinder having a sealing portion 114 that closes one end of the inside (the left end in FIG. 1B) and the other end of the remaining portion of the plurality of flow paths 110 (the right end in FIG. 1B). Is the body.

  The length in the direction in which the flow path 110 of the honeycomb filter 100 extends is not particularly limited, but may be, for example, 40 to 350 mm. Moreover, the outer diameter of the honeycomb filter 100 is not particularly limited, but may be, for example, 100 to 320 mm. The size of the cross section of the flow path 110 can be set to 0.8 to 2.5 mm on a side in the case of a square, for example. The thickness of the partition 112 can be 0.05-0.5 mm.

  It should be noted that by using a high-intensity laser beam or adjusting the particle concentration (mist concentration) in the gas, the inspection accuracy may be improved to some extent even with the conventional inspection method. However, if the outer diameter of the honeycomb filter 100 (distance from the peripheral portion on the light source side of the laser beam to the peripheral portion on the opposite side) is 70 mm or more (more preferably 100 mm or more), the conventional inspection method has sufficient accuracy. The inspection cannot be performed, and the inspection method according to this embodiment is particularly useful.

  The material of the partition 112 of the honeycomb filter 100 is porous ceramics (fired body). The ceramic is not particularly limited, and examples thereof include alumina, silica, mullite, cordierite, glass, oxides such as aluminum titanate, silicon carbide, silicon nitride, and metal. The aluminum titanate can further contain magnesium and / or silicon.

  As described above, the left end of a part of the plurality of channels 110 of the honeycomb filter 100 is sealed by the sealing part 114, and the right end of the remaining part of the plurality of channels 110 of the honeycomb filter 100 is sealed by the sealing part 114. Has been. As the material of the sealing portion 114, the same ceramic material as that of the honeycomb filter 100 can be used. The “part of the plurality of flow paths 110” and the “remaining part of the plurality of flow paths 110” described above are preferably arranged in a matrix when viewed from the end face side as shown in FIG. Of the plurality of flow paths arranged in the vertical direction and the horizontal direction in the horizontal direction.

  Since the honeycomb filter 100 includes the porous partition 112, the gas supplied from the left end of the flow path 110 in FIG. 1B passes through the partition 112 and reaches the adjacent flow path 110. It is discharged from the right end of the flow path 110. At this time, particles in the inflowing gas are removed by the partition 112 and function as a filter.

  Such a honeycomb filter 100 can be manufactured as follows, for example. First, an inorganic compound source powder, an organic binder, a solvent, and additives to be added as necessary are prepared. And these are mixed with a kneader etc. to prepare a raw material mixture, this raw material mixture is extruded from an extruder having an outlet opening corresponding to the shape of the partition wall (extrusion process), cut into a desired length, and then known A green honeycomb molded body is obtained by drying by the method. The end of the channel of the green honeycomb molded body is sealed with a sealing material by a known method (sealing step), and then the green honeycomb molded body is fired to obtain the honeycomb filter 100 (firing step). Alternatively, the green honeycomb molded body may be fired first, and then the end of the flow path may be sealed by a known method to obtain the honeycomb filter 100.

<First Embodiment>
The inspection apparatus for the honeycomb filter 100 will be described with reference to FIGS. The inspection apparatus 400 includes a holding unit 53 that holds the honeycomb filter 100, a mist supply path 54 that guides a gas containing mist (particles) P to one end of the plurality of flow paths 110 of the honeycomb filter 100 (lower ends in FIG. 2), A particle concentration detection unit 200.

  The holding portion 53 is for fixing the honeycomb filter 100 and sealing the gas supplied from the mist supply path 54 so that the gas does not leak from the periphery of the honeycomb filter 100. The holding portion 53 is provided at the tip of the mist supply path 54 and surrounds and seals one end portion (the lower end portion in FIG. 2) in the axial direction of the honeycomb filter 100 (the axial direction of the plurality of flow paths 110) from the outside. It has the cylindrical seal part 51 and the space formation part 52 which forms the reverse conical space V in the part facing the lower end 110b of the some flow path 110. FIG.

  The mist supply path 54 is for supplying a gas containing mist P to the one surface 100 b of the honeycomb filter 100. Although the flow rate of the gas supplied with respect to the honey-comb filter 100 is not specifically limited, For example, it can be set as 100-500 L / min.

  A gas containing mist P may be prepared in advance, and this gas may be supplied to the honeycomb filter 100 through the mist supply path 54. From the viewpoint of obtaining a gas having a high uniformity of mist concentration, as shown in FIG. It is preferable to install the two-fluid nozzle 20 and the mixer 40 in the middle of the supply path 54.

The two-fluid nozzle 20 receives the liquid supplied from the tank 10 via the pump 12 and receives a gas supplied from the gas source 14, for example, air via the valve V <b> 1 and the line L <b> 2 and a gas containing mist. Is generated. The form of the two-fluid nozzle is not particularly limited. Moreover, although the diameter of mist is not specifically limited, For example, it can be set as about 0.1-10 micrometers.
As the liquid, considering the ease of removal after the inspection, a volatile liquid is preferable, and water is particularly preferable.

  The mixer 40 is for sufficiently mixing the gas containing the mist P and other gases. The shape of the mixer 40 is not particularly limited. For example, the mixer 40 has a configuration in which another gas is allowed to flow into the container at a high speed (for example, 1 to 10 m / s), or has a stirring blade in the container. Various things can be used, such as a mixer that causes turbulence of flow due to the interior provided in the container.

  Gas (for example, air) is supplied to the mixer 40 from the gas source 24 via the valve V2. The mist concentration in the mixed gas after mixing is preferably 0.0001 to 0.01 g / L.

The gas of the gas supply sources 14 and 24 is not particularly limited, but air is preferable from the viewpoint of economy. The gases of the gas supply sources 14, 24 may be the same as each other or different from each other.
Moreover, it is preferable that the temperature of the gas of the gas supply sources 14 and 24 is 0-50 degreeC, and it is more preferable that it is 0-30 degreeC.

  The particle concentration detection unit 200 includes a first light source 210A that irradiates a laser sheet (laser light) LS toward the gas discharged from the other ends (upper ends in FIG. 2) of the plurality of flow paths 110 of the honeycomb filter 100; A second light source 210B that irradiates a laser sheet (laser light) whose orientation with respect to the honeycomb filter 100 is different from that of the first light source 210A, and further, a camera 220 that photographs the laser sheet LS, and an image acquired by the camera 220 A computer 230 for analysis is provided.

  As shown in FIGS. 2 and 3, the laser sheet (first laser sheet) LS from the first light source 210A is parallel to the XY plane, which is a direction perpendicular to the Z direction in which the plurality of flow paths 110 of the honeycomb filter 100 extend. And is irradiated in the left direction (the negative direction of X) in FIG. On the other hand, the laser sheet (second laser sheet) LS from the second light source 210B is parallel to the XY plane and irradiated toward the right direction (plus direction of X) in FIG. 3A shows a state in which the laser sheet LS is irradiated from the first light source 210A, and FIG. 3B shows a state in which the laser sheet LS is irradiated from the second light source 210B. The XY plane is a plane parallel to the other end 100t of the honeycomb filter 100, and each laser sheet LS spreads along the other end 100t.

  Here, as shown in FIG. 3, when the first light source 210A and the second light source 210B are provided at positions facing each other, that is, the angle formed by the orientation of the laser sheet from these light sources is 180 °. As an example, the angle formed by the irradiation direction of the first light source 210A and the irradiation direction of the second light source 210B is 160 to 200 ° when viewed from the Z-axis direction perpendicular to the laser sheet LS. It can be a range. In addition, as shown in FIG. 3, when using the light source with which the laser sheet LS is irradiated in a fan shape, “the direction of the laser sheet” means the direction of the center (axis) of the laser sheet (the arrows Da, Db).

  The camera 220 photographs a portion of the laser sheet LS facing the upper end surface 110t of the honeycomb filter 100 from a direction perpendicular to the laser sheet LS (Z direction). A field of view FV of an image captured by the camera 220 is shown in FIG. The shooting timing of the camera 220 and the timing of turning on / off the light sources 210A and 210B can be performed by a controller connected to the camera and the light sources 210A and 210B.

  The computer 230 analyzes an image captured by the camera 220 and detects a portion where particles are discharged. For example, a portion brighter than a predetermined threshold value may be extracted from the image, and this portion may be set as a place where particles are discharged. However, when the outer diameter of the honeycomb filter 100 is relatively large, as shown in FIG. 4A when the first light source 210A is used, the first light source is located at the peripheral edge of the other end face 110t of the honeycomb filter 100. A location Ra away from 210A is brightly illuminated by light emission from the mist, and is easily mistaken for a defective location. On the other hand, when the second light source 210B is used, as shown in FIG. 4B, the peripheral portion Rb of the other end surface 110t of the honeycomb filter 100 and the portion Rb away from the second light source 210B is brightened by the emission of mist. It is illuminated and easily misidentified as a defective part.

  The computer 230 synthesizes an image (first image) acquired when the first light source 210A is used (first image) and an image (second image) acquired when the second light source 210B is used, so that image data with high accuracy as a whole ( Density distribution data). More specifically, in each of the image data, a location where the distance from the light source of the laser beam is short (a region (first portion) Ta in FIG. 4A and a region (second portion) Tb in FIG. 4B). ) And by combining these, image data with high accuracy can be obtained as a whole (see FIG. 4C).

  Since gas containing mist is discharged from this apparatus, it is preferable to provide exhaust means for collecting these gases and exhausting them to the outside.

  Next, an inspection method for the honeycomb filter 100 using the above-described inspection apparatus 400 will be described. Here, as an example, as shown in FIG. 2, the partition wall 112 of the honeycomb filter 100 has, as a defect, a hole h that communicates the flow path 110x with the upper end sealed and the flow path 110y with the lower end sealed. It shall be.

  First, the holding part 53 is attached to the lower part of the honeycomb filter 100. And while opening valve | bulb V1, the pump P12 is driven and the gas containing mist is generated from the two-fluid nozzle 20. FIG. The generated gas containing mist is supplied to the mixer 40 via the pipe 30. Subsequently, the valve V2 is adjusted to supply the gas from the gas source 24 to the mixer 40 via the line L3. Thereby, in the mixer 40, the gas containing the mist from the piping 30 and the gas from the line L3 mix, and the mixed gas with the high uniformity of the mist density | concentration is obtained. And this mixed gas is supplied to the honey-comb filter 100 via the mist supply path 54 (supply process). Thereby, gas flows out from the upper ends 110t of the plurality of flow paths 110 of the honeycomb filter 100. At this time, in the vicinity of the upper ends 110t of the plurality of flow paths 110 of the honeycomb filter 100, it is preferable that the atmosphere gas hardly flow, for example, the flow rate is 1 m / s or less. Moreover, it is preferable that the temperature of atmospheric gas is 0-30 degreeC from the ease of experiment. The atmospheric gas is preferably air.

  And when the hole h as shown in FIG. 2 exists between the flow paths 110, the flow path which connects the upper end 110t and the lower end 110b of the some flow path 110 by the flow path 110x, the hole h, and the flow path 110y. Therefore, as shown by the arrow G, the mixed gas containing mist flows out from the upper end of the defective flow path 110y intensively at a higher flow rate and flow velocity than the other flow paths 110. Similarly, when the sealing part 114 is missing or when there is a defect such as a gap between the sealing part 114 and the flow path 110, the mixed gas containing mist flows out in a concentrated manner. Therefore, above such a flow path 110y, the concentration of mist is relatively higher than in other portions.

  Next, a laser sheet (first laser sheet) LS is irradiated from the first light source 210A, and an image including the other end face 110t of the honeycomb filter 100 is acquired under the irradiated state (first image acquisition step). When the gas flowing out from the upper end of the honeycomb filter 100 has non-uniform mist concentration, the laser sheet LS irradiated from the first light source 210A is scattered when passing through the high concentration portion, and the camera 220 takes an image. It appears as a relatively bright region R1 (see FIG. 4A) in the image. Based on the presence or absence of this bright part, the density unevenness of the particles is detected.

  However, when the outer diameter of the honeycomb filter 100 is relatively large, the region R1 may not be sufficiently bright because the defective portion is relatively far from the first light source 210A. Also, as described above, as shown in FIG. 4A, when the first light source 210A is used, the peripheral portion Ra of the other end face 110t of the honeycomb filter 100 and the portion Ra away from the first light source 210A is bright. It is easy to misrecognize as a defective part.

  Subsequently, the irradiation of the laser sheet LS from the first light source 210A is stopped, and then the laser sheet (second laser sheet) LS is irradiated from the second light source 210B. An image including the other end surface 110t of the filter 100 is acquired (second image acquisition step). Further, in the same manner as described above, unevenness in the concentration of particles is detected based on the presence or absence of a bright portion due to scattering of laser light. Since the defective portion is relatively close to the second light source 210B, the region R2 is observed as brighter light than the region R1 formed by the first light source 210A. However, as shown in FIG. 4 (b), when the second light source 210B is used, the peripheral portion Rb of the other end surface 110t of the honeycomb filter 100 and the portion Rb away from the second light source 210B shines brightly, Easily misunderstood.

  Two image data (FIGS. 4A and 4B) obtained as described above are processed by the computer 230 (data processing step). By performing the data processing step, highly accurate image data (FIG. 4C) is obtained. Thereby, as shown in FIG.4 (c), it can be judged that there exists a defect in the area | region R2 which shines brightly in the synthesized image, and there is no defect in other locations.

  When there is no defect such as communication between the channels 110, the mixed gas flows through the partition walls 112, which are porous bodies, and flows out from the upper end outlet, as indicated by an arrow H in FIG. At this time, the mist in the mixed gas may be collected entirely, partially collected, or not collected at all depending on the diameter of the mist, the size of the pores of the partition 112, etc. Even so, the flow rates and flow rates of the gas flowing out from the upper ends of the respective flow paths 110 are substantially uniform with each other, and therefore, mist concentration non-uniformity hardly occurs on the upper ends 110 t of the flow paths 110.

  According to this embodiment, by detecting the concentration distribution of particles in the gas flowing out from the flow path 110, the presence or absence and location of the flow path can be easily detected. In particular, in the present embodiment, two image data can be acquired using the two light sources 210A and 210B. Therefore, by combining these image data, a more accurate inspection can be performed. In order to further improve the accuracy of the inspection, the combination of the first detection step and the second detection step may be performed a plurality of times, or after a plurality of times of the first inspection step, a plurality of times of the second detection step. The inspection step may be performed.

  The inspection method according to the present embodiment may be incorporated into the manufacturing process of the honeycomb filter 100. That is, the manufacturing method of the honeycomb filter 100 includes, in addition to the above-described extrusion process, sealing process, and firing process, a detection process for detecting defects in the honeycomb filter by the inspection method according to the present embodiment, and defects in the detection process. You may provide the sorting process which sorts the honeycomb filter which is not detected. By performing the sorting step, a honeycomb filter in which no defect is detected can be sent to the next step or can be made into a final product.

Second Embodiment
In the above embodiment, the case where two light sources 210A and 210B are used is exemplified. However, if a mechanism for rotating the honeycomb filter 100 on a plane parallel to the XY plane is employed, the same applies even if there is only one laser light source. Highly accurate inspection can be performed. Hereinafter, the second embodiment will be described mainly with respect to differences from the first embodiment.

  The inspection apparatus 500 shown in FIG. 5 is provided with a joint (rotation mechanism) 54a in the middle of the mist supply path 54 instead of having the second light source 210B, and the mist supply path above the joint 54a. 54 and the holding part 53 rotate together with the honeycomb filter 100. As shown in FIG. 5, the honeycomb filter 100 freely rotates around a central axis parallel to the Z direction, that is, the axis of the honeycomb filter. In addition, when the mist supply path 54 is comprised with a flexible tube, it is not necessary to necessarily provide the joint part 54a. The present embodiment can include a motor that rotates the honeycomb filter 100 about the joint portion 54a.

  In order to inspect defects in the honeycomb filter 100 using the inspection apparatus 500, similarly to the above-described inspection apparatus 400, a laser sheet (first laser sheet) LS is irradiated from the supply step and the light source 210A, and an image of the other end face 110t is obtained. After acquiring and performing the first image acquisition step, the honeycomb filter 100 is rotated 180 ° so that the direction of the laser light from the light source 210A with respect to the honeycomb filter 100 is different from the first detection step, and again, The second image acquisition process may be performed by irradiating a laser sheet (second laser sheet) LS from the light source 210A and taking an image of the other end face 110t. In addition, the angle which rotates the honey-comb filter 100 should just be the range of 160-200 degrees. The shooting timing of the camera 220, the timing of turning on / off the light source 210A, and the driving timing of the motor can be performed by a controller connected thereto.

In the present embodiment, by rotating the honeycomb filter 100, a plurality of image data can be acquired using one light source 210A. By combining these image data, a more accurate inspection can be performed. Similar to the first embodiment described above, the inspection method according to this embodiment may be incorporated into the manufacturing process of the honeycomb filter 100.
<Third Embodiment>
Next, a method according to the third embodiment of the present invention will be described with reference to FIG. This embodiment is different from the first embodiment in that, as shown in FIG. 6 (a), a gas containing particles is supplied to one end face of the honeycomb filter and then discharged from the other end face of the honeycomb filter 100. The point is that an image including the other end face 110t of the honeycomb filter is acquired in a state where the first laser sheet LS1 and the second laser sheet LS2 are irradiated to the gas.
The first laser sheet LS1 is irradiated from the first light source 210A and spreads along the other end surface. The second laser sheet is irradiated from the second light source 210B and spreads along the other end surface. The direction of the first laser sheet LS1 and the direction of the second laser sheet LS2 are different from each other.
The photographing of the camera under the irradiation of the laser sheets LS1 and LS2 can be automatically performed by the light sources 210A and 210B and a controller that controls the camera.
According to the present embodiment, the obtained image is scattered by the two laser sheets LS1 and LS2, as shown in FIG. R3 is observed as particularly bright light. Accordingly, the region R3 can be easily distinguished from Ra and Rb scattered by one laser sheet. Therefore, also in this embodiment, the defective portion can be determined with high accuracy.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various modifications can be made.
For example, in the above embodiment, a two-fluid nozzle is adopted as a method for generating mist, but the present invention is not limited to this. For example, other nozzles may be used, and water and dry ice are mixed. A mist may be produced by the use of a glycol alcohol (for example, propylene glycol). In the above embodiment, mist, that is, liquid particles are employed as the particles. However, the present invention is not limited to this, and the present invention can also be implemented using solid particles such as carbon black.

  Further, the direction of the laser sheet and the direction of the camera are not limited to the above embodiment.

  Moreover, in the said embodiment, although atmospheric gas is air, it cannot be overemphasized that other gas may be used as atmospheric gas.

  Moreover, in the said embodiment, although the flow path 110 of the honey-comb filter 100 is arrange | positioned at the up-down direction, it can implement in any direction, such as a horizontal direction.

  Moreover, in the said embodiment, although the cross-sectional shape of the flow path 110 is substantially square, it is not limited to this, It can be made into a rectangle, a circle, an ellipse, a triangle, a hexagon, an octagon, etc. Moreover, in the flow path 110, those with different diameters and those with different cross-sectional shapes may be mixed. In addition, although the arrangement of the channels is a square arrangement in FIG. 1, the arrangement is not limited to this, and the equilateral triangle arrangement in which the central axis of the channel is arranged at the apex of the equilateral triangle in the cross section, In the case of a square, a staggered arrangement can be used. Further, the outer shape of the honeycomb filter is not limited to a cylindrical shape, and may be, for example, an elliptical column, a triangular column, a quadrangular column, a hexagonal column, an octagonal column, or the like.

  In the above-described embodiment, the honeycomb filter is a fired body in which the partition walls are porous. However, the honeycomb filter can also be implemented in a non-porous green body before firing. In this case, there is no outflow of gas from the channel without defects.

  In the above embodiment, the presence / absence of particles is determined by a computer based on an image obtained by the camera 220, but the presence / absence and position of a bright spot may be determined manually.

53 ... Holding part, 54 ... Mist supply path, 54a ... Joint part (rotating mechanism), 100 ... Honeycomb filter, 100b ... One side of the honeycomb filter, 100t ... The other end face of the honeycomb filter, 110b ... Lower end (one end face) of the honeycomb filter ), 110t ... upper end (other end surface), 200 ... particle concentration detector, 210A ... first light source, 210B ... second light source, 400, 500 ... inspection device, LS ... laser sheet (laser light), P ... mist (particle).

Claims (14)

A method for inspecting a honeycomb filter for defects,
Supplying a gas containing particles to one end face of the honeycomb filter;
A first image for acquiring a first image including the other end face of the honeycomb filter under a state in which a gas discharged from the other end face of the honeycomb filter is irradiated with a first laser sheet that spreads along the other end face. Acquisition process;
After the first image acquisition step, the second laser sheet that spreads along the other end surface of the gas discharged from the other end surface of the honeycomb filter is irradiated in a different direction from the first laser sheet, A second image acquisition step of acquiring a second image including the other end face of the honeycomb filter.   The method according to claim 1, wherein the first laser sheet is irradiated from a first light source, and the second laser sheet is irradiated from a second light source different from the first light source. The first laser sheet and the second laser sheet are irradiated from one light source,
The method further includes the honeycomb after the first image acquisition step and before the second image acquisition step so that the direction of the second laser sheet is different from the direction of the first laser sheet. The method of claim 1, comprising rotating the filter.   The method according to any one of claims 1 to 3, further comprising a determination step of determining whether or not the honeycomb filter has a defect based on the first image and the second image.   In the determining step, a first portion of the first image that is close to the light source of the first laser sheet is extracted, and a second portion of the second image that is close to the light source of the second laser sheet is extracted, The method according to claim 4, wherein the presence or absence of a defect in the honeycomb filter is determined based on the first portion and the second portion. A method for inspecting a honeycomb filter for defects,
Supplying a gas containing particles to one end face of the honeycomb filter;
The first laser sheet that spreads along the other end surface and the second laser sheet that spreads along the other end surface of the gas discharged from the other end surface of the honeycomb filter are oriented in the direction of the first laser sheet and the first laser sheet. 2. An inspection method comprising: an image acquisition step of acquiring an image including the other end face of the honeycomb filter under a state where the two laser sheets are irradiated in different directions.   The method according to any one of claims 1 to 6, wherein an angle formed by an orientation of the first laser sheet and an orientation of the second laser sheet is 160 to 200 °.   The method according to claim 1, wherein the particles are generated by supplying a liquid and a gas to a two-fluid nozzle.   The method according to any one of claims 1 to 8, wherein the particles are produced by mixing water and dry ice.   The method according to any one of claims 1 to 9, wherein the honeycomb filter partition walls are porous. An inspection device for defects in honeycomb filters,
A holding part for holding the honeycomb filter;
A supply path for supplying a gas containing particles to one end face of the honeycomb filter;
A first light source that irradiates a first laser sheet that spreads along the other end surface toward the gas discharged from the other end surface of the honeycomb filter;
A second light source that irradiates a second laser sheet that extends along the other end face toward the gas discharged from the other end face of the honeycomb filter in a different direction from the first laser sheet;
A camera that acquires an image including the other end face of the honeycomb filter. An inspection device for defects in honeycomb filters,
A rotating mechanism for holding the honeycomb filter and rotating the honeycomb filter about the central axis of the honeycomb filter;
A supply path for supplying a gas containing particles to one end face of the honeycomb filter;
A light source that irradiates a laser sheet that spreads along the other end surface toward the gas discharged from the other end surface of the honeycomb filter;
A camera that acquires an image including the other end face of the honeycomb filter.   The apparatus according to claim 11 or 12, further comprising a detection unit that detects the presence or absence of a defect in the honeycomb filter based on a plurality of images acquired by the camera. A detection step of detecting defects in the honeycomb filter by the method according to any one of claims 1 to 10,
And a sorting step of sorting out the honeycomb filter in which no defect is detected in the detection step.