JP5952530B2 - Method for inspecting defects in green honeycomb molded body, and inspection apparatus for defects in green honeycomb molded body - Google Patents

Description

  The present invention relates to a method for inspecting a defect of a green honeycomb molded body and a defect inspection apparatus for a green honeycomb molded body.

  Conventionally, a defect inspection method for a green honeycomb molded body, which is a molded body before firing of a so-called honeycomb filter, is known. For example, in Patent Documents 1 and 2, a gas flow containing fine particles is provided to the inlet end surface of the green honeycomb molded body, and the gas flow exiting the outlet end surface of the green honeycomb molded body is passed through a permeable member such as a screen. It is disclosed that fine particles exiting the transmissive member are illuminated with a light source.

Special table 2009-503508 gazette Special Table 2002-357562

  However, in the conventional method, since the fine particles remain in the green honeycomb molded body, it is necessary to remove the fine particles after the inspection, which is complicated.

  This invention is made | formed in view of the said subject, and it aims at providing the method and apparatus which can test | inspect the defect of a green honeycomb molded object easily.

  According to a first aspect of the present invention, partition walls forming a plurality of flow paths extending in parallel with each other, one end of a part of the plurality of flow paths, and the other end of the remaining part of the plurality of flow paths are provided. This is a method for inspecting a defect of a green honeycomb molded body having a sealing portion to be closed. The method includes a step of applying pressure by gas to one end of the plurality of flow paths, and a step of visualizing the distribution of the gas refractive index in the vicinity of the other ends of the plurality of flow paths.

  According to the present invention, when there is no defect that the flow paths communicate with each other and there is no defect in the sealing portion, one end or the other end of each flow path is closed by the sealing portion, so that the gas passes through the flow path and passes through the flow path. It does not flow out from the other end. On the other hand, when there is a defect that allows the flow paths to communicate with each other in the partition wall or there is a defect in the sealing portion of the flow path, the gas for applying pressure passes through the flow path from the other end of the flow path. leak. Therefore, by making the refractive index of the leaking gas different from the refractive index of the atmospheric gas in the vicinity of the other end, the refractive index distribution changes, and by visualizing this change, the presence or absence and location of defects can be detected.

  Here, the refractive index distribution is preferably visualized by any one of the shadow graph method, the Mach-Zehnder method, and the Schlieren method, and particularly preferably detected by the Schlieren method.

  Further, when the density of the atmospheric gas in the vicinity of the other end of the plurality of flow paths is 1 at 0 ° C. and 1 atm, the density of the gas for applying the pressure is 0.1 to 0.9 at 0 ° C. and 1 atm. Or it is preferable that it is 1.1-5.0. Thereby, a sufficient refractive index difference is given between the atmospheric gas and the leaking gas, and the gas leak can be suitably detected.

  Specifically, it is preferable to apply pressure to one end of the plurality of channels with a gas having a composition different from that of the atmospheric gas in the vicinity of the other end of the plurality of channels.

  In particular, the atmosphere gas in the vicinity of the other ends of the plurality of flow paths is air, and the gas for applying pressure is selected from the group consisting of helium, neon, nitrogen, argon, xenon, krypton, oxygen, and carbon dioxide. Any one of the above gases, or a mixed gas of two or more members in this group, or a mixed gas of one or more members in this group and air is preferable.

  In addition, it is also preferable to apply pressure to one end of the plurality of flow paths with a gas having a temperature different from that of the atmospheric gas in the vicinity of the other end of the plurality of flow paths. Even when a gas having the same composition as the atmospheric gas in the vicinity of the other end of the path is used, a density difference can be given to the gas, and visualization is possible.

  Further, in the visualizing step, it is preferable to arrange a scale within the visual field to be visualized (preferably in the vicinity of the other ends of the plurality of flow paths), so that it is easy to identify the location where the gas has leaked, and the position of the defect is determined. Easy to grasp.

  In the visualization step, it is preferable to visualize the refractive index distribution of the gas in the vicinity of the other ends of the plurality of flow paths from a direction orthogonal to the axes of the plurality of flow paths. Thereby, it is easy to detect a gas leak.

  In particular, in the visualization step, it is preferable to visualize the refractive index distribution of the gas in the vicinity of the other ends of the plurality of flow paths from two directions orthogonal to the axes of the plurality of flow paths. Thereby, two-dimensional information (for example, coordinates) about the location of leakage is obtained, and the defective flow path can be easily identified.

  The green honeycomb molded body preferably includes an inorganic compound source and a binder.

  In the second aspect of the present invention, partition walls forming a plurality of flow paths extending in parallel to each other, one end side of a part of the plurality of flow paths, and the other end side of the remaining part of the plurality of flow paths are provided. It is an inspection apparatus for defects in a green honeycomb molded body having a sealing portion to be closed. This device includes a pressure applying member that applies pressure by a gas supplied from a gas supply source to one end of a plurality of flow paths, and a visualization unit that visualizes the distribution of gas refractive indexes in the vicinity of the other ends of the plurality of flow paths. And comprising.

A method for manufacturing a honeycomb filter according to the present invention includes a step of selecting a honeycomb formed body having no defects by the above-described inspection method,
Firing the selected honeycomb formed body.

  According to the present invention, it is possible to easily inspect a defect of the green honeycomb molded body.

FIG. 1A is a perspective view of a green honeycomb molded body 100 to be inspected, and FIG. 1B is a view taken in the direction of arrows Ib-Ib in FIG. FIG. 2 is a schematic cross-sectional view of a defect inspection apparatus 400 for the green honeycomb molded body 100. FIG. 3 is a top view of FIG. 4A and 4B are schematic views of images 400A and 400B taken by the cameras of the schlieren units 300A and 300B, respectively.

  An embodiment of the invention will be described with reference to the drawings. First, the green honeycomb molded body 100 to be inspected in the present embodiment will be described.

  As shown in FIGS. 1A and 1B, a green honeycomb molded body 100 that is a target in the present embodiment includes partition walls 112 that form a plurality of channels 110 that extend in parallel to each other, and a plurality of channels. 110 is a sealing portion 114 that closes one end (left end in FIG. 1B) of a part of 110 and the other end (right end in FIG. 1B) of the remaining part of the plurality of flow paths 110. It is the cylinder which has.

  The length in the direction in which the flow path 110 of the green honeycomb molded body 100 extends is not particularly limited, but may be, for example, 40 to 350 mm. Moreover, the outer diameter of the green honeycomb molded body 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.

  The green honeycomb molded body 100 is green (unfired body) that becomes porous ceramics when fired, and is a non-porous material containing a ceramic raw material. 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.

  The green honeycomb molded body 100 preferably includes an inorganic compound source powder that is a ceramic raw material, an organic binder such as methylcellulose, and an additive that is added as necessary.

  For example, when the ceramic is aluminum titanate, the inorganic compound source powder includes an aluminum source powder such as α-alumina powder, and a titanium source powder such as anatase-type or rutile-type titania powder. Magnesium source powder such as magnesia powder and magnesia spinel powder and / or silicon source powder such as silicon oxide powder and glass frit can be included.

  Examples of the organic binder include celluloses such as methylcellulose, carboxymethylcellulose, hydroxyalkylmethylcellulose, and sodium carboxymethylcellulose; alcohols such as polyvinyl alcohol; and lignin sulfonate. The amount of the organic binder is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and still more preferably 6 parts by weight with respect to 100 parts by weight of the inorganic compound source powder. Moreover, it is preferable that the minimum amount of an organic binder is 0.1 weight part, More preferably, it is 3 weight part.

  Examples of the additive include a pore-forming agent, a lubricant and a plasticizer, a dispersant, and a solvent.

  Examples of the pore-forming agent include carbon materials such as graphite; resins such as polyethylene, polypropylene, and polymethyl methacrylate; plant materials such as starch, nut shells, walnut shells, and corn; ice; and dry ice. The amount of pore-forming agent added is preferably 0 to 40 parts by weight, more preferably 0 to 25 parts by weight with respect to 100 parts by weight of the inorganic compound source powder.

  Lubricants and plasticizers include alcohols such as glycerin; higher fatty acids such as caprylic acid, lauric acid, palmitic acid, arachidic acid, oleic acid and stearic acid; stearic acid metal salts such as Al stearate; polyoxyalkylene alkyl Examples include ether. The addition amount of the lubricant and the plasticizer is preferably 0 to 10 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the inorganic compound source powder.

  Examples of the dispersant include inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid; organic acids such as oxalic acid, citric acid, acetic acid, malic acid and lactic acid; alcohols such as methanol, ethanol and propanol; ammonium polycarboxylate Surfactant etc. are mentioned. It is preferable that the addition amount of a dispersing agent is 0-20 weight part with respect to 100 weight part of an inorganic compound source powder, More preferably, it is 2-8 weight part.

  As the solvent, for example, alcohols such as methanol, ethanol, butanol and propanol; glycols such as propylene glycol, polypropylene glycol and ethylene glycol; and water can be used. The amount of the solvent used is preferably 10 to 100 parts by weight, more preferably 20 to 80 parts by weight with respect to 100 parts by weight of the inorganic compound source powder. Moreover, the weight of the solvent with respect to the weight of the whole green honeycomb molded body is not particularly limited, but is preferably 10 to 30 wt%, and more preferably 15 to 20 wt%.

  As described above, the left end of a part of the plurality of channels 110 of the green honeycomb molded body 100 is sealed by the sealing portion 114, and the remaining right end of the plurality of channels 110 of the green honeycomb molded body 100 is sealed. Sealed by the portion 114. As the sealing portion 114, a material that becomes ceramics by firing, similar to the green honeycomb molded body 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.

  Such a green honeycomb molded object 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. These are mixed by a kneader or the like to obtain a raw material mixture. The obtained raw material mixture is extruded from an extruder having an outlet opening corresponding to the shape of the partition wall, cut to a desired length, and then dried by a known method. By doing so, the green honeycomb molded object 100 can be obtained. Then, what is necessary is just to seal the edge part of the flow path 110 by a well-known method.

Next, an inspection apparatus for the green honeycomb molded body 100 will be described with reference to FIGS. 2 and 3.
The inspection apparatus 400 includes a pressure applying member 200 for applying pressure by a gas supplied from a gas supply source 210 to one end (lower end in FIG. 2) of the plurality of flow paths 110 of the green honeycomb molded body 100, and a plurality of Schlieren units 300A and 300B as visualization units for visualizing the gas refractive index distribution near the other end (upper end in FIG. 2) of the flow path 110, and scales 360A and 360B are provided.

  The pressure application member 200 includes a cylindrical seal portion 201 that surrounds and seals one end portion (the lower end portion in FIG. 2) of the green honeycomb molded body 100 in the axial direction (the axial direction of the plurality of flow paths 110) from the outside. And a space forming portion 202 that forms a space V at a portion facing the lower end 110b of the channel 110.

  A gas supply source 210 is connected to the space forming unit 202 via a line L1 having a valve V1.

  The gas of the gas supply source 210 is not particularly limited as long as it has a refractive index different from the atmospheric gas in the vicinity of the upper ends 110 t of the plurality of flow paths 110. In order to obtain different refractive indexes, the gas density may be changed. The density of the gas of the gas supply source 210 is 0.1 to 0.9 or 1.1 to 5.0 at 0 ° C. and 1 atm, with the density of the atmospheric gas (for example, air) at 0 ° C. and 1 atm being 1. Preferably there is.

  Specifically, for example, a gas having a composition different from the atmospheric gas may be used as the gas of the gas supply source 210. For example, the atmospheric gas is preferably air for ease of inspection, and when the atmospheric gas is air, it is selected from the group consisting of helium, neon, nitrogen, argon, xenon, krypton, oxygen, and carbon dioxide. Any one of the above gases, or two or more kinds of mixed gases (excluding the air composition) in this group, or one or more kinds in this group and air are preferable. Moreover, it is preferable that the temperature of the gas of the gas supply source 210 is 0-30 degreeC.

  Further, even when the composition of the gas of the gas supply source 210 and that of the atmospheric gas are the same, the gas of the gas supply source 210 is in a state of leaking into the atmospheric gas by setting the temperature of the gas different from that of the atmospheric gas. It is also possible to give a density difference, that is, a refractive index difference. In this case, the temperature difference is preferably 10 to 50 ° C. Of course, both the composition and the temperature may be different.

  The schlieren portions 300A and 300B shown in FIG. 3 visualize the gas refractive index distribution in the vicinity of the upper ends 110t of the plurality of channels 110 of the green honeycomb molded body 100 as shown in FIG. , And an observation unit 302. The light source unit 301 includes a light source 340 and a collimator lens 350 that collimates the light emitted from the light source 340. The observation unit 302 converges the light emitted from the collimator lens 350 and passed on the upper ends 110t of the plurality of flow paths 110, the knife edge 330 provided at the focal position of the converged light, and the knife edge A camera 310 that captures an image of light after passing through 330 is provided.

  In the present embodiment, as shown in FIG. 3, the light source unit 301 and the observation unit 302 of the first schlieren unit 300A are separated from each other in the X direction, which is a direction perpendicular to the Z direction in which the plurality of flow paths 110 extend. The portions near the upper ends 110t of the plurality of flow paths 110 are arranged so as to sandwich them. On the other hand, the light source unit 301 and the observation unit 302 of the second schlieren unit 300B are spaced apart from each other in the Y direction, which is a direction perpendicular to the Z direction in which the plurality of flow paths 110 extend, and the upper ends 110t of the plurality of flow paths 110. It arrange | positions so that the part of the vicinity may be pinched | interposed. Thereby, the refractive index distribution of the gas in the vicinity of the upper ends 110t of the plurality of channels 110 can be visualized from two directions (X direction and Y direction) orthogonal to the Z axis that is the axis of the plurality of channels 110, respectively. ing.

  As shown in FIGS. 2 and 3, the scale 360A exists in the field of view observed by the schlieren unit 300A, and the scale 360B exists in the field of view observed by the schlieren unit 300B. It is arranged above the upper end 110t of the path 110 and closer to the light source part 301 of each schlieren part 300A, 300B. The scales 360A and 360B have marks 361 at positions corresponding to the central axes of the plurality of flow paths 110 when viewed from the observation unit 302 of the schlieren units 300A and 300B, respectively.

  Next, an inspection method for the green honeycomb molded body 100 using the above-described inspection apparatus 400 will be described.

  Here, as an example, as shown in FIG. 2, the partition 112 of the green honeycomb molded body 100 has, as a defect, a hole that communicates the flow path 110x with the upper end sealed and the flow path 110y with the lower end sealed. Suppose there is h. Here, as shown in FIGS. 2 and 3, the channel 110x is at the position of the leftmost mark 361 on the scale 360B and at the position of the third mark 361 from the bottom on the scale 360A. On the other hand, it is assumed that the flow path 110y is at the position of the second mark 361 from the left in the scale 360B, and is at the position of the third mark 361 from the bottom in the scale 360A.

  First, the pressure applying member 200 is attached to the lower part of the green honeycomb molded body 100. And valve | bulb V1 is open | released and the pressure by gas is applied to the lower end of the some flow path 110 of the green honeycomb molded object 100 by argon gas, for example (process of applying a pressure). Although a pressure is not specifically limited, For example, it can be set as 0.01-1 Mpa as a differential pressure | voltage with respect to atmospheric pressure. And it is preferable to make the atmosphere gas flow in the vicinity of the upper ends 110t of the plurality of flow paths 110, for example, at a flow velocity of 1 m / s or less. Moreover, it is preferable that the temperature of atmospheric gas is 0-30 degreeC from the ease of experiment.

  When the pressure is applied in this manner, when the hole h as shown in FIG. 2 exists, the flow path 110x, the hole h, and the flow path that connects the upper end 110t and the lower end 110b of the plurality of flow paths 110 by the flow path 110y. Therefore, the gas G used for pressurization flows out from the upper end of the channel 110y having the defect. The same applies when the sealing portion 114 is missing or when there is a defect such as a gap between the sealing portion 114 and the flow path 110. On the other hand, if the green honeycomb molded body 100 does not have the above-described defects, even if pressure is applied to the lower ends of the plurality of flow paths 110, the gas passes over the upper ends 110t of the plurality of flow paths 110. Cannot flow out, and the gas does not flow out on the upper ends 110t of the plurality of flow paths 110.

  Since the refractive index of the gas G is different from the refractive index of the atmospheric gas in the vicinity of the upper ends of the plurality of flow paths 110, when there is a defect, unevenness in the refractive index occurs in the vicinity of the upper ends of the flow paths 110y.

  Then, the unevenness of the refractive index is visualized as a difference between light and dark by the schlieren portions 300A and 300B (visualization step). For example, schematic diagrams of images 400A and 400B taken by cameras of the schlieren units 300A and 300B are shown in FIGS. 4A and 4B, respectively.

  In the image 400A, a portion D having a density based on unevenness of the refractive index is seen on the third mark 361 from the left of the scale 360A. In the image 400B, the refractive index is placed on the second mark 361 from the left of the scale 360B. A portion D with shading based on the unevenness of the image can be seen, and data of coordinates (3, 2) can be obtained.

  Based on the images 400A and 400B, the presence / absence and position of the part D may be determined manually, but the presence / absence and position of the part D may be determined by a known image processing method.

  According to the present invention, unevenness of the refractive index is generated in the vicinity of the flow path 110y according to the presence or absence of a defect in the flow path, and the presence or location of the defect can be easily detected by visualizing this.

  In particular, in this embodiment, the distribution of the refractive index of the gas in the vicinity of the upper ends 110t of the plurality of flow paths 110 is changed from two directions (X direction and Y direction) orthogonal to the axis (Z axis) of the plurality of flow paths 110. Since each of the portions 300A and 300B is visualized, two-dimensional information (coordinates) can be obtained for a place where the refractive index is uneven, and a defective flow path can be easily identified. Further, the provision of the scales 360A and 360B makes it easier to identify defective flow paths.

  Further, since it is not necessary to add fine particles other than gas (for example, glycol fine particles or water vapor mist) to the gas, it is not necessary to remove the fine particles after the inspection, which is convenient.

  Then, the ceramic honeycomb fired body formed from the ceramic porous body is obtained by firing the green honeycomb molded body determined to be a non-defective product according to the present embodiment by a known method. This ceramic honeycomb fired body can be used as a diesel particle filter (DPF) or the like.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the above embodiment, the Schlieren method is adopted as a method for visualizing the refractive index distribution, but the method is not limited to this as long as the refractive index difference of the gas can be visualized. For example, the shadow graph method or the Mach Zender You may adopt the law.

  Further, in the above embodiment, the two schlieren portions 300A and 300B are provided. However, even if only one of the schlieren portions is provided, it is possible to determine the presence or absence of a defect, and the position of an approximate defect can be grasped. .

  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 green honeycomb molded object 100 is arrange | positioned at the up-down direction, it can implement in which 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, the arrangement of the channels is also a square arrangement in FIG. 1, but is not limited to this, and may be an equilateral triangle arrangement, a staggered arrangement, etc. in which the central axis of the channel is arranged at the apex of the equilateral triangle in the cross section. it can. Further, the external shape of the green honeycomb molded body is not limited to a cylindrical shape, and may be, for example, a triangular prism, a quadrangular prism, a hexagonal prism, an octagonal prism, or the like.

  DESCRIPTION OF SYMBOLS 100 ... Green honeycomb molded object, 110 ... Channel, 110t ... Upper end (one end) of a channel, 110b ... Lower end (other end) of a channel, 112 ... Partition, 114 ... Sealing part, 200 ... Pressure application member, 300A, 300B ... Visualization unit, 360 ... Scale, 400 ... Inspection device.

Claims (10)

Green honeycomb molding having partition walls forming a plurality of channels extending in parallel to each other, and a sealing portion for closing one end of a part of the plurality of channels and the other end of the remaining part of the plurality of channels A method for inspecting body defects,
Applying a gas pressure to one end of the plurality of flow paths;
Visualizing the gas refractive index distribution near the other end of the plurality of flow paths,
In the visualization step, the refractive index distribution of the gas in the vicinity of the other ends of the plurality of flow paths is visualized from two directions orthogonal to the axes of the plurality of flow paths,
A method for inspecting a defect of a green honeycomb molded body , wherein a scale is arranged in each visual field to be visualized in the visualizing step .   The method according to claim 1, wherein the refractive index distribution is visualized by one of a shadow graph method, a Mach-Zehnder method, and a Schlieren method.   The method according to claim 1, wherein the refractive index distribution is detected by a Schlieren method.   When the density of the atmospheric gas near the other end of the plurality of flow paths is 1 at 0 ° C. and 1 atm, the density of the gas for applying the pressure is 0.1 to 0.9 at 0 ° C. and 1 atm. Or it is 1.1-5.0, The method as described in any one of Claims 1-3.   The method according to any one of claims 1 to 4, wherein pressure is applied to one end of the plurality of flow paths by a gas having a composition different from that of the atmospheric gas in the vicinity of the other ends of the plurality of flow paths.   The atmosphere gas near the other end of the plurality of flow paths is air, and the gas for applying the pressure is selected from the group consisting of helium, neon, nitrogen, argon, xenon, krypton, oxygen, and carbon dioxide. 6. The method according to claim 5, wherein the gas is one of two or more kinds of mixed gases in the group, or a mixed gas of one or more kinds in the group and air.   The method according to claim 1, wherein a pressure is applied to one end of the plurality of flow paths by a gas having a temperature different from that of the atmospheric gas in the vicinity of the other end of the plurality of flow paths. The method according to any one of claims 1 to 7 , wherein the green honeycomb molded body includes an inorganic compound source and a binder. Green honeycomb molding having partition walls forming a plurality of channels extending in parallel to each other, and a sealing portion for closing one end of a part of the plurality of channels and the other end of the remaining part of the plurality of channels An inspection device for body defects,
A pressure applying member for applying a pressure by a gas supplied from a gas supply source to one end of the plurality of flow paths;
A plurality of visualization units for visualizing the distribution of the gas refractive index in the vicinity of the other ends of the plurality of flow paths from two directions orthogonal to the axes of the plurality of flow paths ;
And a scale provided in each of the visual fields of the plurality of visualization units. Selecting a honeycomb formed body having no defects by the method according to any one of claims 1 to 8 ,
Firing the selected honeycomb formed body. A method for manufacturing a honeycomb filter.

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