JP4474633B2 - Method for manufacturing ceramic honeycomb structure - Google Patents

Description

【００４３】
表１から、本発明例のセラミックハニカム構造体の製造方法によれば、アイソスタティック強度及び耐熱衝撃性に優れたハニカム構造体が得られることがわかる。また、本発明の実施例２及び３の、外皮の厚さの不均一を小さくしたハニカム構造体によれば、特に耐熱衝撃性に優れたハニカム構造体の得られることが判る。
【００４４】
【発明の効果】
以上、説明のとおり、本発明のハニカム構造体及びその製造方法によれば、成形時に外皮及びその近傍に発生する変形したセルを除去する工程を適切に選択することで、焼成時に割れが進展しにくく、ハニカム構造体の外周面に、外部との間の隔壁を有しない外部に開口する凹溝を確実に形成し、そのために外皮とハニカム本体とが剥離し難く、優れたアイソスタティック強度を有し、かつ周縁部の除去加工の効率が向上できるハニカム構造体を得ることができる。
【図面の簡単な説明】
【図１】 （ａ）本発明の実施の形態１に係る工程図である。
（ｂ）本発明の参考例に係る工程図である。
【図２】 ハニカム構造体の斜視図である。
【図３】 従来の技術における周縁部除去加工後の周縁部隔壁のカケを示す模式図である。
【図４】 本発明の実施の形態に係わるハニカム焼成体の焼成台と当接した開口端面が除去されたハニカム構造体を示す概略図である。
（ａ）ハニカム乾燥体を焼成台に載置した状態を示す概略図。
（ｂ）焼成台に載置されたハニカム焼成体を示す概略図。
（ｃ）ハニカム焼成体の焼成台と当接した開口端面が除去されたハニカム構造体を示す概略図である。
【図５】 本発明の実施の形態に係わるハニカム乾燥体からハニカム焼成体に至る寸法変化の程度を予測し、該予測された寸法に従ってセラミックハニカム乾燥体周縁部の除去加工を行ったことを示す概略図である。
（ａ）予測された寸法に従って除去加工されたハニカム乾燥体を焼成台に載置したことを示す概略図。
（ｂ）上記、乾燥体が焼成された状態を示す概略図。
【図６】本発明における外皮形成法を示す概略図である。
【符号の説明】
１：ハニカム構造体
２：外皮
４、３４：隔壁
５、３５：セル
３１、３１ａ：凹溝
４０：ハニカム構造の焼成台
４１：セラミックハニカム乾燥体
４２：セラミックハニカム焼成体
４３：焼成台に当接した端面が除去されたセラミックハニカム焼成体
４４：焼成台に当接した開口端面
４５：予測された寸法に従って周縁部が除去加工されたハニカム乾燥体
４６：セラミックハニカム焼成体
５１：円盤状挟持用部材
５２：外皮[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for manufacturing a ceramic honeycomb structure.
[0002]
[Prior art]
  In order to reduce the harmful substances contained in the exhaust gas of engines such as automobiles, the catalytic converter for exhaust gas purification is used from the viewpoint of the preservation of the local environment and the global environment. Recently, a porous ceramic honeycomb structure (hereinafter referred to as “honeycomb structure” for short) is used to collect graphite fine particles contained in exhaust gas from diesel engines. An exhaust gas purification filter in which both ends of cell openings of this honeycomb structure are alternately sealed has been used.
[0003]
  FIG. 2 is a perspective view of the honeycomb structure. As shown in FIG. 2, the honeycomb structure 1 usually has a large number of cells 5 formed by outer skins 2 and partition walls 4 orthogonal to the inner peripheral side thereof. The honeycomb structure 1 is firmly held by a holding member disposed between the inner peripheral surface of the storage container and the outer peripheral surface of the honeycomb structure so as not to move in a metal storage container (not shown). Are stored.
[0004]
  The honeycomb structure 1 is conventionally manufactured by the following steps.
  A honeycomb structure in which the outer skin 2 and the partition walls 4 are formed by extruding a ceramic clay obtained by mixing and kneading a cordierite-forming raw material powder, a molding aid, a pore former and water through a special mold. A molded body having Next, the moisture in the molded body is evaporated and dried in a drying furnace, and further, a molding aid such as a binder in the molded body is removed by a firing furnace, and then fired at a predetermined temperature to have a predetermined shape. And a honeycomb structure 1 having fine pores in the partition walls 4 was obtained.
[0005]
  Now, for example, when manufacturing a large-sized ceramic honeycomb structure having an outer diameter of 150 mm or more and a length of 150 mm or more for a diesel engine, or a thin honeycomb structure 1 having a cell wall 4 having a thickness of 0.2 mm or less, At the time of extrusion molding, the weight of the molded body is too large or the strength of the molded body itself is insufficient, so that the weight of the molded body cannot be supported, and the partition wall 4 at the peripheral edge of the outer skin 2 is crushed or deformed, and after firing There was a problem that a predetermined strength could not be obtained.
[0006]
  To solve this problem, the ceramic clay is extruded, dried, and fired to obtain a fired body having a honeycomb structure, and then the outer skin 2 and the peripheral edge of the fired body having the honeycomb structure are ground from a predetermined diameter. There is a description of an invention in which a removal process is performed to make it smaller, and a coating material is applied to the removed outer peripheral surface, dried and cured to form an outer skin (see, for example, Patent Document 1). According to the invention described in Japanese Patent Laid-Open No. 3-275309, since the outer skin 2 of the fired body having a honeycomb structure and the peripheral portion thereof are removed by grinding, cells in which the peripheral portion is deformed can be removed. The mechanical strength can be increased. Further, even when the roundness of the entire fired body having a honeycomb structure is poor, the dimensional accuracy is improved by forming the outer skin after increasing the roundness by grinding.
[0007]
[Patent Document 1]
          JP-A-3-275309
[0008]
[Problems to be solved by the invention]
  However, the invention described in JP-A-3-275309 has the following problems.
  Crushing or deformation of cells at the periphery of a molded body that occurs during extrusion molding of a large honeycomb structure having an outer diameter of 150 mm or more and a length of 150 mm or more, or a thin wall honeycomb structure having a partition wall thickness of 0.15 mm or less Since a molded body having the above defects will have residual stress accompanying molding and drying, if firing is performed with these defects, cracks will develop from the defective portion to release the residual stress, and the fired body Cracks may develop throughout. This crack may not be completely removed even if the peripheral portion of the fired body is removed, and there is a problem that the manufacturing yield is lowered.
  Further, when the peripheral portion of the ceramic honeycomb fired body is removed, the fired body is hard and brittle. Therefore, an enlarged view after the peripheral portion removal processing is located at the outermost periphery of the outer peripheral surface as shown in FIG. The partition wall 34 that forms the recessed groove 31 that opens to the outside that does not have a partition wall between them is likely to be chipped, and is likely to be shaped like an incomplete recessed groove 31a in which a part of the partition wall is missing. Even if the skin is formed in the groove, there is a problem that the adhesion area between the partition walls and the skin is reduced, the skin strength (isostatic strength) is reduced, and the skin is easily peeled from the honeycomb body. When such a honeycomb structure is used as a catalytic converter or a filter for collecting particulates, the outer skin peels off from the honeycomb structure due to engine vibration or road surface vibration, and an appropriate gripping force cannot be secured in the storage container. The honeycomb structure moves in the storage container, and in some cases, the honeycomb structure may be damaged.
  Furthermore, in the invention described in JP-A-3-275309, the processing method for removing the peripheral portion of the ceramic honeycomb fired body is preferably ground, and the processing condition is a peripheral speed of 750 to 2100 m / min. A grindstone that rotates at high speed is used, and the processing speed is preferably in the range of 0.7 to 0.9 mm / min. In the case of a partition structure such as a honeycomb structure, since the partition wall intermittently collides with a processing tool, so-called intermittent processing is performed, so that a processing amount such as feeding and cutting must be reduced, and processing time is reduced. There was a problem of becoming enormous. Further, since the fired body is hard and brittle, it is necessary to use an expensive grindstone such as a diamond grindstone for the grinding process.
[0009]
  Therefore, an object of the present invention is to appropriately select a process for removing the outer skin and the deformed cells generated in the vicinity thereof when forming the honeycomb structure, so that cracks hardly progress during firing, and the outer peripheral surface of the honeycomb structure. In addition, a groove that opens to the outside that does not have a partition wall between the outside and the outside is surely formed, so that the outer shell and the honeycomb body are difficult to peel off, have an excellent isostatic strength, and a peripheral edge removal process. Honeycomb structure with improved efficiencyManufacturing methodThere is in getting.
[0010]
[Means for Solving the Problems]
  The present inventionExtruded, dried and fired ceramic clayHaving a large number of cells formed by barrier ribsIn the method for manufacturing a ceramic honeycomb structure as a ceramic honeycomb structure,Obtaining a molded body having a honeycomb structure in which an outer skin and partition walls are formed by the extrusion molding,AboveMolded bodyDrydidThe periphery of the dried ceramic honeycombBy cuttingAfter the removal processing, an outer skin is formed on the outer peripheral surface of the ceramic honeycomb fired body obtained by firing the ceramic honeycomb dried body.
[0011]
  The present inventionIn the method for manufacturing the ceramic honeycomb structure, the ceramic honeycomb dried body is fired by placing the open end face of the ceramic honeycomb dried body on the firing table and firing the ceramic honeycomb dried body. It is preferable to remove the opened end face.
  Also,The present inventionIn the method for manufacturing the ceramic honeycomb structure of the present invention, the removal processing of the peripheral portion of the ceramic honeycomb dried body is performed by predicting the degree of dimensional change from the honeycomb dried body to the honeycomb fired body by a firing operation, and drying the ceramic honeycomb according to the predicted dimensions. It is preferable to perform removal processing of the peripheral part of the body.
  And it is preferable to remove at least a part of the outer skin after firing.
[0012]
  Next, the function and effect of the present invention will be described.
  The present inventionIn this case, since a part of the peripheral portion of the honeycomb structure in contact with the outer skin is removed before firing, the outer skin generated at the time of extrusion and the deformed portion of the cell in the vicinity thereof are removed before firing. At the time of firing, there is less fear that cracks will develop into the honeycomb structure starting from these, so that the cracks generated at the time of firing can be reduced, and the production yield can be improved.
  In addition, since the peripheral portion of the honeycomb structure in contact with the outer skin is removed and processed in the state of the dried body before firing, the dried body is reinforced with a molding aid such as an organic binder. The problem of chipping of the partition wall, which is located at the outermost periphery of the outer peripheral portion and is formed in the outer groove that does not have a partition wall between the outside and hardly forms, is generated when the part is removed. Since it is difficult to form an incomplete groove 31a partially missing, it is possible to secure a sufficient bonding area between the partition wall and the outer skin, and the outer skin strength (isostatic strength) is reduced or the outer skin is easily peeled off from the honeycomb body. Problems are less likely to occur.
  Furthermore, since the peripheral portion of the honeycomb structure in contact with the outer skin is removed and processed in the state of a dry body before firing, there is no need for grinding as in the case of removing the peripheral portion of the fired body, and cutting processing is performed. Therefore, the time required for processing can be shortened. Further, it is not necessary to use a diamond grindstone, and a carbide tool or the like can be used, so that the processing cost can be reduced.
[0013]
  The present inventionIn the case where the outer peripheral surface of the ceramic honeycomb fired body obtained by firing the ceramic honeycomb dried body after removing the peripheral portion of the dried ceramic honeycomb dried body, A groove formed on the outer peripheral surface of the dry body, which is formed by removing the peripheral edge of the dry body, and is open to the outside without a partition wall between the outer and the outer surface of the fired body after firing. By forming a groove and applying a coating material for forming the outer skin to this concave groove, drying and firing as necessary, and integrating the outer wall and the partition wall constituting the concave groove, Since the adhesion area is increased, the outer skin is difficult to peel from the honeycomb body, and an excellent isostatic strength can be obtained.
  Here, the peripheral portion refers to the outer skin of the honeycomb structure and the partition wall on the inner peripheral side, and it is preferable to remove at least two cells from the outer peripheral surface during the removal processing. More preferably, it is removed.
  Here, as the coating material to be applied to form the outer skin, ceramic fiber, cement, inorganic binder, etc. are singly added to heat-resistant ceramic aggregate particles such as cordierite, silica, alumina, mullite, silicon carbide, silicon nitride, etc. Alternatively, it is preferable to use a mixture, and an organic binder or the like may be further mixed if necessary, but is not limited thereto. It is more preferable to select an aggregate of the same material as the material constituting the ceramic honeycomb structure because the difference in the thermal expansion coefficient between the outer skin and the partition wall can be suppressed small.
  still,The present inventionIn this case, after the peripheral portion of the ceramic honeycomb dried body is removed, the outer surface of the ceramic honeycomb fired body obtained by firing the ceramic honeycomb dried body is finished and then the outer skin may be formed. Also,The present inventionThen, after the outer peripheral surface of the ceramic honeycomb dried body obtained by firing the ceramic honeycomb dried body after removing the peripheral portion of the ceramic honeycomb dried body, May be processed again.
[0014]
  Furthermore, in the present invention, when the ceramic honeycomb dried body is fired, after the ceramic honeycomb dried body is placed and fired so that the opening end surface of the ceramic honeycomb dried body is in contact with the fired stand, By removing the contacted opening end face, the outer skin thickness of the honeycomb structure can be made uniform.
  The above reason will be described using an example in which a skin is formed on the outer peripheral surface of a ceramic honeycomb fired body obtained by firing after the peripheral portion of the ceramic honeycomb dried body is removed.
  In general, in the process from the dried body to the fired body due to the firing operation of the ceramic, the firing reaction of the ceramic proceeds, so that a dimensional change occurs. This dimensional change is not a problem when it occurs uniformly over the entire honeycomb structure, but in the case of a large ceramic honeycomb structure having an outer diameter of 150 mm or more and a length of 150 mm or more used for exhaust gas purification of a diesel engine. Depending on the material selection of the ceramic, the degree of dimensional change may be different at various locations of the ceramic honeycomb structure. For example, the open end surface that comes into contact with the firing table on which the honeycomb dried body is placed during firing may be affected by the degree of dimensional change due to the restraint by the firing table. As shown in a schematic diagram of an example in FIG. 4, the outer diameter of each part of the dried body was uniform at the stage of finishing the dried body shown in FIG. In the stage, the opening end surface that is in contact with the baking table is restricted by the baking table, and the outer diameter may increase or the roundness may deteriorate. On the other hand, as shown in the schematic diagram of FIG. 6 (a), the outer skin formation method is larger than the outer diameter of the ceramic honeycomb fired body fired after removing the peripheral portion with a dry body, and the honeycomb after the skin formation is performed. Two disc-shaped sandwiching members 51 having the same outer diameter as the structure are sandwiched between both end faces of the ceramic honeycomb fired body 46 so that the space 50 between the sandwiching member and the outer peripheral surface of the ceramic honeycomb fired body is filled. It is performed by a method of filling a forming coating agent. At this time, in the case of the ceramic honeycomb fired body 42 shown in FIG. 4B, where the outer diameter size of the ceramic honeycomb fired body is different in various places, as shown in FIG. The honeycomb structure having non-uniform thickness of the ceramic honeycomb structure may cause a problem that cracks due to thermal shock are likely to occur at the thick thickness of the skin. there were.
  For this reason, as shown in FIG. 4C, the outer diameter of the ceramic honeycomb fired body can be made uniform by removing the opening end face in contact with the firing table, so that a skin having a uniform thickness can be obtained.
[0015]
  Further, in the present invention, the removal processing of the peripheral portion of the dried ceramic honeycomb body is performed by predicting the degree of dimensional change from the dried honeycomb body to the honeycomb fired body by a firing operation, and removing the peripheral edge portion of the ceramic honeycomb dried body according to the predicted dimensions. By performing the processing, the outer skin thickness of the honeycomb structure can be made uniform.
  For example, a dry body is extracted from a molding lot molded under the same conditions, fired by a prior test, and the shape of the dry body shown in FIG. 4 (a) is the shape of the fired body as shown in FIG. 4 (b). When it is found that there is a degree of dimensional change, the dimensional change rate of each part of the honeycomb structure is obtained, and the dried body is processed into the shape of the dried body 45 shown in FIG. Since it becomes possible to obtain a fired body 46 with good dimensional accuracy after firing as shown in FIG. 5B and it is not necessary to remove the contact surface with the firing table, the material yield is improved. More preferred. A honeycomb structure having a uniform skin thickness can be obtained by forming a skin on the fired body using the disc-shaped sandwiching member 51 shown in FIG.
  In the above, an example in which the degree of change in the outer dimensions from the dried body to the fired body differs in the flow direction of the honeycomb structure has been described using schematic diagrams. However, the cross-sectional shape of the honeycomb structure differs in the direction of the partition walls. In such a case, for example, when the outer peripheral edge of the cross section of the dry body changes to a substantially elliptic shape after firing, the dimensional change from the dry body obtained by the three-dimensional measuring device to the fired body It goes without saying that the dry body can be processed by determining the removal processing size of the dry body based on the degree, and using a three-dimensional processing machine or the like according to the determined size.
[0016]
  The present inventionIn the case where the isostatic strength of the ceramic honeycomb structure is 1.0 MPa or more, the outer shell and the honeycomb structure are difficult to peel off, and an appropriate gripping force is secured in the storage container. In some cases, the honeycomb structure is less likely to be damaged. The isostatic strength is preferably 1.5 MPa or more.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail based on examples.
Example 1
  A description will be given based on the process diagram shown in FIG.
  First, adjust the powder of kaolin, talc, silica, alumina, etc.₂: 48-52%, Al₂O_Three: A cordierite-forming raw material powder containing 33-37% and MgO: 12-15%. Also, in the cordierite-forming raw material powder, 7 parts by mass of methylcellulose and hydroxypropylmethylcellulose as a molding aid are added in total to 100 parts by mass of the cordierite-forming raw material, and an appropriate amount of graphite is added as a pore-forming agent. , Dry and mixed well. Next, a specified amount of water was added and further kneading was performed to produce a clay.
[0018]
  Next, the kneaded material was extruded with an extrusion mold and further cut to obtain a formed body having a honeycomb structure in which the outer skin 2 and the partition walls 4 were integrally formed. Next, this molded body was dried by heating in a dielectric drying furnace to evaporate water in the molded body to obtain a dried body.
[0019]
  Next, the dry body is gripped by a processing jig on a lathe and rotated at a rotation speed of 260 rpm, and the peripheral edge of the outer peripheral surface of the dry body is cut with a carbide tool attached to the tool post at 5 mm and the feed is 1.0 mm / second. Removal processing was carried out under conditions, and 3 cells with the outer skin 2 and the deformed cells at the peripheral edge thereof were removed. A concave groove is formed which is located on the outermost periphery of the outer peripheral portion of the dried body from which the peripheral portion has been removed and opens to the outside without having a partition wall between the outer periphery.
[0020]
  Next, the dried body whose peripheral portion has been processed and removed is placed so that one opening end face is in contact with the firing table of the honeycomb structure, and is placed in a firing furnace, and the temperature rising rate from room temperature to 500 ° C. is 5 ° C. The baking was carried out by heating at a heating rate of 20 ° C./hour from 500 ° C. to 1425 ° C./hour and holding at the maximum temperature for 10 hours, and then gradually cooling. As a result, the fired honeycomb body having an outer diameter of 264.7 to 265.7 mm, a length of 300 mm, a partition wall thickness of 0.3 mm, a cell 5 pitch of 1.5 mm, and a pore porosity of 65% after firing. Got.
[0021]
  And the coating material which consists of a cordierite aggregate and a binder was prepared as a material for outer skin. The cordierite aggregate used for the coating material uses cordierite particles having an average particle size of 10 μm, the inorganic binder uses colloidal silica, and 7 mass of colloidal silica with respect to 100 mass parts of cordierite particles. The ratio of parts was adjusted. An organic binder and water were added to this and used as a paste-like coating material. Then, the honeycomb fired body obtained by firing the dried honeycomb body whose peripheral portion was processed and removed was sandwiched between the sandwiching members shown in FIG. 6 and applied to the outer peripheral surface so that the outer diameter was 266.7 mm. Then, the water | moisture content in a coating material was dried on conditions of 120 degreeC for 2 hours, and the outer skin was baked on conditions of 850 degreeC for 2 hours. At this time, the outer skin thickness was 0.5 mm to 1.5 mm.
[0022]
  The isostatic strength of the prepared honeycomb structure was measured. The isostatic strength is based on the automobile standard (JASO) M505-87 issued by the Japan Automobile Engineers Association, and 10 mm thick aluminum plates are applied to the upper and lower surfaces of the ceramic honeycomb structure 1 to seal both ends and thicken the outer periphery of the side. A sample was adhered with 2 mm rubber. And this sample was put in the pressure vessel, water was introduced into the pressure vessel, the pressure in the pressure vessel was increased to break the sample, and the pressure (MPa) at the time of breakage was measured. The pressure at the time of fracture was 1.0 MPa or more was accepted, ○ was 1.0 MPa or more and less than 1.5 MPa, ○ was 1.5 MPa or more, ◎ was less than 1.0 MPa. Table 1 shows the results of evaluation with x as NG.
  Moreover, the thermal shock resistance of the obtained ceramic honeycomb structure was evaluated. In the thermal shock resistance evaluation test, the ceramic honeycomb structure was inserted into an electric furnace heated to a constant temperature (room temperature + 450 ° C), held for 30 minutes, then rapidly cooled to room temperature, and visually observed for cracks. did. Moreover, when a crack was not discovered, the temperature of the electric furnace was raised to 25 ° C., the same test was performed, and the test was repeated until the crack was generated. And the maximum temperature difference temperature difference (heating temperature-room temperature) in which the crack was not discovered was made into the thermal shock temperature. When the thermal shock temperature difference at this time was 500 ° C. or higher, the result was evaluated as “Excellent” when the temperature was 550 ° C. or higher. Is shown in Table 1.
[0023]
(Reference example)
  A description will be given based on the process diagram shown in FIG.
  As in Example 1, raw material mixing, kneading, clay adjustment, extrusion molding, drying and peripheral edge processing were performed.
[0024]
  Next, powders such as kaolin, talc, silica, and alumina are prepared as materials for the outer skin, and in terms of mass ratio, SiO₂: 48-52%, Al₂O_Three: Cordierite-producing raw material powder containing 33 to 37%, MgO: 12 to 15%, 0.5 parts by mass of methylcellulose is added to 100 parts by mass of the powder, and a dispersant and water can be added to the powder. A paste-like coating material was prepared. Then, the honeycomb dried body whose peripheral portion has been processed and removed is sandwiched between the sandwiching members shown in FIG. 6, and applied to the outer peripheral surface of the dried body so that the thickness of the outer skin after firing is about 1.6 mm. Formed.
[0025]
  Next, the dried body coated with the outer skin 2 is placed so that one opening end surface is in contact with the firing table having the honeycomb structure, and is placed in a firing furnace, and heated to 1425 ° C. under the same conditions as in Example 1. The mixture was fired and then gradually cooled. After firing, a honeycomb fired body having an outer diameter of 266.7 to 267.7 mm, a length of 300 mm, a partition wall thickness of 0.3 mm, a cell 5 pitch of 1.5 mm, and a pore porosity of 65% was obtained. . Here, since the outer diameter became 266.7 to 267.7 mm along with the dimensional change at the time of firing after the coating of the outer skin material, the outer diameter becomes 266.7 mm by removing the portion having the larger outer diameter. I made it. The thickness of the outer skin at this time was 0.6 mm to 1.6 mm.
[0026]
  Table 1 shows the results obtained by measuring the isostatic strength and the thermal shock temperature of the honeycomb structure produced in the same manner as in Example 1.
[0027]
(Comparative example)
  The example which removed the peripheral part after baking without removing a peripheral part after drying which is a prior art is shown.
  Adjust the powder of kaolin, talc, silica, alumina, etc.₂: 48-52%, Al₂O_Three: A cordierite-forming raw material powder containing 33-37% and MgO: 12-15%. Also, in the cordierite-forming raw material powder, 7 parts by mass of methylcellulose and hydroxypropylmethylcellulose as a molding aid are added in total to 100 parts by mass of the cordierite-forming raw material, and an appropriate amount of graphite is added as a pore-forming agent. , Dry and mixed well. Next, a specified amount of water was added and further kneading was performed to produce a clay.
[0028]
  Next, the kneaded material was extruded with an extrusion mold and further cut to obtain a formed body having a honeycomb structure in which the outer skin 2 and the partition walls 4 were integrally formed. In addition, the cell wall which deform | transformed by the influence of the dead weight of the molded object existed in the peripheral part of the molded object.
[0029]
  Next, this molded body was dried by heating in a dielectric drying furnace to evaporate water in the molded body to obtain a dried body.
[0030]
  This dried body was placed so that one open end face was in contact with the firing table having the honeycomb structure, placed in a firing furnace, heated to 1425 ° C. under the same conditions as in Example 1, and then fired. Cooling was performed gradually. A honeycomb structure 1 having an outer diameter of 274.7 mm, a length of 300 mm, a partition wall thickness of 0.3 mm, a cell 5 pitch of 1.5 mm, and a pore porosity of 65% was obtained. Many of the fired bodies were cracked by the influence of the deformed cell.
[0031]
  Next, the fired body that was not cracked in the firing step is attached to an outer peripheral grinding machine, and the periphery of the fired body is removed by about 4.5 mm (for 3 cells) and ground until the outer diameter becomes 265.7 mm. Processing was performed to remove the deformed partition walls of the outer skin and the peripheral edge thereof. Of the diamond wheel used at this timePeripheral speedWas 2000 m / min, and the feed rate was 0.5 mm / min. The outer peripheral portion of the dried body that has been processed to remove the peripheral edge is located on the outermost periphery, and a concave groove that opens to the outside not having a partition wall with the outside is formed. Many scraps were generated during removal processing.
[0032]
  And the coating material which consists of a cordierite aggregate and a binder was prepared as a material for an outer skin like Example 1. The cordierite aggregate used for the coating material uses cordierite particles with an average particle size of 10 μm, the inorganic binder uses colloidal silica, and 7 parts of colloidal silica is used for 100 parts by weight of the cordierite particles. The ratio of parts was adjusted. An organic binder and water were added to this and used as a paste-like coating material. And it apply | coated to the outer peripheral surface of the honeycomb calcination body obtained by baking the honeycomb dried body from which the peripheral part was processed and removed by thickness of 0.8-1.2 mm. Then, the water | moisture content in a coating material was dried on condition of 120 degreeC for 2 hours, and the outer skin was baked on condition of 850 degreeC for 2 hours.
  Table 1 shows the results obtained by measuring the isostatic strength and the thermal shock temperature of the honeycomb structure produced in the same manner as in Example 1.
[0033]
(Example2)
  In the same manner as in Example 1, raw material mixing, kneading, clay adjustment, extrusion molding, and drying were performed to obtain a cordierite ceramic honeycomb dried body.
  Next, the outer peripheral surface peripheral edge portion of the dry body is removed in the same manner as in Example 1, and the outer skin 2 and three cells with deformed cells on the peripheral edge portion are removed, and the outer peripheral portion of the dry body is positioned at the outermost peripheral portion. As a result, a dried body in which a concave groove opened to the outside without a partition wall between the outside and the outside was formed was obtained. At this time, the length of the dried body was processed to be 50 mm longer than that of Example 1 in terms of the length of the fired body.
[0034]
  Next, the dried body from which the peripheral edge portion was processed and removed was placed so that one of the opening end faces abuts on the honeycomb structure firing table in the same manner as in Example 1, and was placed in a firing furnace, from room temperature to 500 ° C. The temperature was raised at a rate of 5 ° C./hour, a temperature rise rate of 20 ° C./hour from 500 ° C. to 1425 ° C. and held at the maximum temperature for 10 hours, and then gradually cooled. As a result, after firing, a honeycomb fired body having an outer diameter of 264.7 to 265.7 mm, a length of 350 mm, a partition wall thickness of 0.3 mm, a cell 5 pitch of 1.5 mm, and a pore porosity of 65%. Got. Thereafter, the end portion was cut and removed at a length of 50 mm from the end face in contact with the firing table of the honeycomb fired body to obtain a honeycomb fired body having an outer diameter of 265.5 to 265.9 mm and a length of 300 mm.
[0035]
  Then, as a material for the skin, a paste-like coating material prepared by adjusting colloidal silica to a ratio of 7 parts by mass to 100 parts by mass of cordierite aggregate having an average particle diameter of 10 μm as in Example 1 is prepared, and the peripheral part is prepared. It was applied to the outer peripheral surface of the honeycomb fired body obtained by firing the processed and dried honeycomb body so that the outer diameter was 266.7 mm. Then, the water | moisture content in a coating material was dried on conditions of 120 degreeC for 2 hours, and the outer skin was baked on conditions of 850 degreeC for 2 hours. At this time, the skin thickness was 0.8 mm to 1.2 mm.
[0036]
  Table 1 shows the results obtained by measuring the isostatic strength and the thermal shock temperature of the honeycomb structure produced in the same manner as in Example 1.
[0037]
(Example3)
  In the same manner as in Example 1, raw material mixing, kneading, clay adjustment, extrusion molding, and drying were performed to obtain a cordierite ceramic honeycomb dried body.
  Next, the peripheral edge of the dry body is removed in the same manner as in Example 1, 3 cells with the outer skin 2 and the deformed cells of the peripheral edge are removed, and the outer peripheral surface of the dry body is located on the outermost periphery. A dried body in which a concave groove opened to the outside having no partition wall between the outside and the outside was formed was obtained. At this time, the outer diameter of the dried body was determined based on the result of Example 1 after grasping in advance the degree of dimensional change from the dried body to the fired body, as shown in FIG. .
[0038]
  Next, the dried body from which the peripheral edge portion was processed and removed was placed so that one opening end face was in contact with the firing torch of the honeycomb structure in the same manner as in Example 1, and placed in a firing furnace, from room temperature to 500 ° C. The temperature was raised at a rate of 5 ° C./hour, a temperature rise rate of 20 ° C./hour from 500 ° C. to 1425 ° C. and held at the maximum temperature for 10 hours, and then gradually cooled. As a result, a fired honeycomb body having an outer diameter of 265.4 to 265.9 mm, a length of 300 mm, a partition wall thickness of 0.3 mm, a cell 5 pitch of 1.5 mm, and a pore porosity of 65% after firing. Got.
[0039]
  Then, as a material for the outer skin, a paste-like coating material prepared by adjusting colloidal silica to a ratio of 5 parts by mass to 100 parts by mass of cordierite aggregate having an average particle diameter of 10 μm as in Example 1 is prepared. It was applied to the outer peripheral surface of the honeycomb fired body obtained by firing the processed honeycomb dried body so that the outer diameter was 266.7 mm. Then, the water | moisture content in a coating material was dried on conditions of 120 degreeC for 2 hours, and the outer skin was baked on conditions of 850 degreeC for 2 hours. At this time, the outer skin thickness was 0.8 mm to 1.2 mm.
[0040]
  Table 1 shows the results obtained by measuring the isostatic strength and the thermal shock temperature of the honeycomb structure produced in the same manner as in Example 1.
[0041]
(Example4)
  In the same manner as in Example 1, raw material mixing, kneading, clay adjustment, extrusion molding, and drying were performed to obtain a cordierite ceramic honeycomb dried body. Next, the peripheral part of the ceramic honeycomb dried body is removed, the outer skin and the deformed three cells of the peripheral part are removed, and firing is performed in the same manner as in Example 1 to locate the outermost peripheral surface, A ceramic honeycomb fired body in which a concave groove opened to the outside without having a partition wall between the outside and the outside was formed. This fired body had an outer diameter of 264.7 to 265.7 mm, a length of 300 mm, a partition wall thickness of 0.3 mm, a cell pitch of 1.5 mm, and a porosity of 62%.
Then, as a material for the outer skin, it is adjusted to a ratio of 7 parts by mass of colloidal silica to 100 parts by mass of amorphous silica aggregate particles having an average particle diameter of 14 μm, and further, an organic binder and water are added to form a paste-like coating The material was prepared, and the honeycomb fired body obtained by firing the honeycomb dried body whose peripheral portion was processed and removed was sandwiched between the sandwiching members shown in FIG. 6 and applied to the outer peripheral surface so that the outer diameter was 266.7 mm. Then, the water | moisture content in a coating material was dried on conditions of 120 degreeC for 2 hours, and the outer skin was baked on conditions of 850 degreeC for 2 hours. At this time, the outer skin thickness was 0.5 mm to 1.5 mm.
  Table 1 shows the results obtained by measuring the isostatic strength and the thermal shock temperature of the honeycomb structure produced in the same manner as in Example 1.
[0042]
[Table 1]

[0043]
  From Table 1, it can be seen that according to the method for manufacturing a ceramic honeycomb structure of the present invention example, a honeycomb structure excellent in isostatic strength and thermal shock resistance can be obtained. Examples of the present invention2as well as3It can be seen that according to the honeycomb structure in which the nonuniformity of the thickness of the outer skin is reduced, a honeycomb structure having particularly excellent thermal shock resistance can be obtained.
[0044]
【The invention's effect】
  As described above, according to the honeycomb structure of the present invention and the manufacturing method thereof, cracks develop during firing by appropriately selecting a process of removing the deformed cells generated in the outer skin and the vicinity thereof during molding. It is difficult to form a concave groove that opens to the outside without having a partition wall between the outside and the outer surface of the honeycomb structure. Therefore, the outer skin and the honeycomb body are difficult to peel off and have excellent isostatic strength. And the honeycomb structure which can improve the efficiency of the removal process of a peripheral part can be obtained.
[Brief description of the drawings]
FIG. 1A is a process diagram according to a first embodiment of the present invention.
  (B) of the present inventionReference exampleIt is process drawing concerning.
Fig. 2 is a perspective view of a honeycomb structure.
FIG. 3 is a schematic diagram showing chipping of a peripheral edge partition wall after peripheral edge removal processing in a conventional technique.
Fig. 4 is a schematic view showing a honeycomb structure in which an opening end face in contact with a firing table of the honeycomb fired body according to the embodiment of the present invention is removed.
(A) Schematic which shows the state which mounted the honeycomb dried body on the baking stand.
(B) Schematic showing the honeycomb fired body placed on the firing table.
(C) It is the schematic which shows the honeycomb structure from which the opening end surface contacted with the baking stand of the honeycomb fired body was removed.
FIG. 5 shows that the degree of dimensional change from the honeycomb dried body to the honeycomb fired body according to the embodiment of the present invention was predicted, and the peripheral edge of the ceramic honeycomb dried body was removed according to the predicted dimensions. FIG.
(A) Schematic which shows having mounted the honeycomb dried body removed according to the estimated dimension on the baking stand.
(B) The schematic which shows the state by which the said dried body was baked.
FIG. 6 is a schematic view showing a skin forming method in the present invention.
[Explanation of symbols]
  1: Honeycomb structure
  2: Outer skin
  4, 34: Bulkhead
  5, 35: Cell
  31, 31a: concave groove
  40: Firing stand with honeycomb structure
  41: Ceramic honeycomb dried body
  42: Ceramic honeycomb fired body
  43: Ceramic honeycomb fired body from which the end face contacting the firing table is removed
  44: Open end face in contact with firing table
  45: Dried honeycomb body with peripheral edge removed according to predicted dimensions
  46: Ceramic honeycomb fired body
  51: Disc-shaped clamping member
  52: Hull

Claims (4)

In the method for manufacturing a ceramic honeycomb structure, which is obtained by extruding a ceramic clay, drying and firing, and forming a ceramic honeycomb structure having a large number of cells formed by partition walls. to obtain a molded product having a structure, the outer peripheral surface of said after a peripheral portion of the ceramic honeycomb dried body after the molded body is dried to remove machining by cutting, a ceramic honeycomb fired body obtained by firing the ceramic honeycomb dried body A method for manufacturing a ceramic honeycomb structure, wherein an outer skin is formed on the ceramic honeycomb structure. When firing the ceramic honeycomb dried body, the opening end face of the ceramic honeycomb dried body is placed on the firing table and fired, and then the opening end face contacting the firing table of the ceramic honeycomb fired body is removed. The method for manufacturing a ceramic honeycomb structure according to claim 1 . The removal process of the peripheral part of the ceramic honeycomb dried body is performed by predicting the degree of dimensional change from the dried honeycomb body to the honeycomb fired body by a firing operation, and removing the peripheral part of the ceramic honeycomb dried body according to the predicted dimensions. A method for manufacturing a ceramic honeycomb structure according to claim 1 or 2 . The method for manufacturing a ceramic honeycomb structure according to any one of claims 1 to 3, wherein at least a part of the outer skin is removed after the firing.

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