DE102009001820A1 - Process for producing ceramic honeycomb structural body - Google Patents

Abstract

A method for producing the ceramic honeycomb structural body is disclosed, which comprises the steps of forming a compact ceramic honeycomb body by extruding a ceramic clay composed of a certain ceramic material and an assistant through a mold having a certain lattice-like recess pattern, calcining the ceramic honeycomb a compact ceramic honeycomb body at a temperature lower than a sintering temperature to form a calcined ceramic honeycomb body, processing a peripheral edge portion of the calcined ceramic honeycomb body to be removed to form a processed ceramic honeycomb body, forming an outer wall having a certain film thickness at one outer circumferential periphery of the processed ceramic honeycomb body by applying thereto an outer wall-forming material, and simultaneously sintering the outer wall and the processed ceramic Honeycomb body to thereby form a ceramic honeycomb structural body in a unitary structure.

Description

 Background of the invention

1. Technical field of the invention

The The present invention relates to methods of preparation ceramic honeycomb structural body and, more specifically, on Process for producing a ceramic honeycomb structural body for use as a ceramic carrier body for a combustion exhaust gas purifying catalyst or a Diesel particulate filter for trapping exhaust particles.

2. Description of the associated State of the art

In the related art has been an attempt taken a ceramic honeycomb structural body as a carrier body for an exhaust gas purification catalyst or a diesel particulate filter (DPF) in a combustion exhaust passage an internal combustion engine such as a car engine or the like to install. When manufacturing the ceramic honeycomb structural body becomes ceramic Clay by kneading a mixture of basic raw material powder, the a composition of desired ceramic material has educational aids such as adhesion promoters, plasticizers and pore-forming agents and dispersants such as water or the like produced. Resulting ceramic clay is passed through a mold extruded with a specific recess pattern, creating a more compact ceramic honeycomb body is formed, which is a nearly cylindrical outer wall with one with partitions split interior has a large number of each defined in a particular form cells to define. Subsequently, the compact ceramic honeycomb body dried and then fired, creating a ceramic honeycomb structural body is formed.

In producing the ceramic honeycomb structural body, a part of the intermediate walls tends to deform with the occurrence of bent cells, and the outer wall is subjected to stress deformation by its own weight of the compact ceramic honeycomb body during its formation. In addition, there is another problem of occurrence of cracks in the outer wall due to the nonuniformity of a wall thickness. The published Japanese patent application ( Japanese Publication No. 3-275309 ) discloses a method for producing a ceramic honeycomb structural body by extruding ceramic clay to form a compact ceramic honeycomb body, drying the compact ceramic honeycomb body, and firing the compact ceramic honeycomb body to form a sintered ceramic honeycomb body. Subsequently, a peripheral edge of the sintered ceramic honeycomb body is processed by grinding to remove it, thereby removing deformed cells. Then, coating material is applied to the outer surface of the sintered ceramic honeycomb body to form an outer circumferential wall portion. This allows the ceramic honeycomb structural body to have increased mechanical strength, roundness and dimensional precision.

In In recent years, an attempt has been made, the ceramic To form honeycomb structural bodies with partitions, which are formed with further thinned wall thicknesses, in the intention of the heat capacity of a ceramic Reduce carrier body to enable that activates the catalyst in an earlier phase is and for the purpose of increased cell density to one increased capture capacity. thats why it is necessary for the ceramic honeycomb structural body an increased dimensional precision, mechanical Strength and strength for thermal shock resistance exhibit.

Indeed, in the manufacturing process described in such an above Related Art, when the material, which forms the fired ceramic honeycomb body, and the coating material on the outside Surface of the fired ceramic honeycomb body is applied, are different in their composition, do not match the thermal expansion coefficients, what a risk of a deficiency, occurring in the strength of Thermal shock resistance when used under High temperature conditions caused.

Further, as disclosed in the related art mentioned above, the coating material is applied to the fired ceramic honeycomb body and then fired, with the intention of increasing the heat resistance. Even if such steps are carried out, re-firing the fired ceramic honeycomb body already subjected to the firing step results in an excess firing effect with a consequent decrease in the porosity rate. Therefore, there is a risk a difficulty in achieving an original target of the ceramic honeycomb structural body, that is, a function of the filter or the catalyst carrier body. In addition, re-firing of the fired ceramic honeycomb body results in a change in dimension, with a dimensional change occurring in the coating material applied to the outer circumferential wall. Therefore, there is a difference between these parameters, with the resulting occurrence of thermal stress. This results in a risk of flaking the outer circumferential wall of the fired ceramic honeycomb body or the crack occurrence in the outer circumferential wall.

Farther The fired ceramic honeycomb body generally has one higher hardness, with a difficulty that Processing of the realize. Therefore, the process requires in which the outer circumferential edge region After the sintering step is processed, an extremely longer Processing time with a resulting increase in Costs.

Summary of the invention

The The present invention has been completed with the above-mentioned intentions and has the task of a method for producing a ceramic To provide honeycomb structural body, the excellent dimensional precision, mechanical strength and strength for thermal shock resistance having.

Around To achieve the above object is the present invention a method for producing a ceramic honeycomb structural body with a nearly cylindrical outer circumference ready, with partitions formed in a certain profile is split to form a variety of cells, called gas flow passages Act. The method comprises the steps of: kneading a mixture a specific ceramic material and a specific auxiliary agent, to form a kneaded molding material; Forming a compact ceramic honeycomb body by extruding the kneaded one Mold material through a mold with a specific grid-like Recess pattern; and calcining the compact ceramic honeycomb body at a lower temperature than a sintering temperature, to form a calcined ceramic honeycomb body; Processing a peripheral edge region of the calcined ceramic Honeycomb body forming to make a processed ceramic To remove honeycomb body is; Forming an outer wall on an outer circumferential perimeter of the processed ceramic honeycomb body, by applying a Exterior wall-forming material; and simultaneous sintering the outer wall and the processed ceramic honeycomb body, thereby the ceramic honeycomb structural body in a unify structure to form.

at the manufacturing process of the above steps, leads calcining the compact ceramic honeycomb body to the formation of the calcined ceramic honeycomb body, having a strength to withstand the processing step. This allows the calcined ceramic honeycomb body in a successful effect to handle, to cracked and bent Cells that occur during the molding step, and a Defect, such as the occurrence of an eccentric effect, remove. In addition, the calcined ceramic honeycomb body has Room to vary in size during sintering, so as to minimize the occurrence of stress caused by a difference between the dimensional change of the calcined ceramic Honeycomb body and a dimensional change of the outer circumferential Wall made on the surface of the processed ceramic Honeycomb body is formed during sintering arises. Accordingly, this leads to a capability a ceramic honeycomb structural body having a smaller one Number of defects and excellent dimensional precision with increased thermal shock resistance receive.

at the method for producing the ceramic honeycomb structural body For example, the outer wall-forming material may preferably be in one Slurry or sludge state or a paste state is used become. For this purpose, a ceramic raw material, a dispersant, a binder and a viscosity and elasticity adjusting agent Means in such a pulp or mud condition or a paste condition mixed. The ceramic raw material has the same basic composition when subjected to the sintering step, such as that of the ceramic material.

at Such a manufacturing process can be processed ceramic honeycomb body and the outer wall to a unified structure are sintered. this makes possible it, the ceramic honeycomb structural body with a lower Number of defects and with excellent dimensional precision and increased thermal shock resistance receive.

In the method for producing the ceramic honeycomb structural body, the outer wall bil The preferred material preferably has a relative sintering change rate ΔS between a calcined body sintering change rate S _BOD and an outer wall sintering change rate S _SKN to satisfy the relationship defined in Formula 1 below. -1.5 ≤ ΔS ≤ 0.5 Formula 1 in which ΔS = S BOD - p SKN (%) S BOD = 100 · D CFD / D PRE (%) S SKN = 100 · T CFD / T CTD (%) wherein S _{BOD represents} the calcined body sintering change rate of the calcined ceramic honeycomb body subjected to the sintering step, which is calculated by dividing a dimension D _CFD of the calcined body subjected to the sintering step by a dimension D _{PRE of} the calcined body at a stage prior to the sintering step Representing index indicating a calcined body sintering change of the calcined ceramic honeycomb body when subjected to the sintering step; and S _SKN represents the outer wall sintering change rate obtained by dividing a film thickness dimension T _{CFD of} the outer wall subsequent to the sintering step by a film thickness dimension T _{CTD of} the outer wall at a stage prior to the sintering step to represent another index indicating a sintering change of the outer wall indicates when it is subjected to the sintering step.

at such a manufacturing method, by adjusting the sintering change rate of exterior wall-forming material, there is no difference in the coefficient of thermal expansion between that of such a Outside wall-forming material produced outer wall and the calcined ceramic honeycomb body. this makes possible it, the outer wall and the processed ceramic honeycomb body without sintering the occurrence of thermal stress to thereby the ceramic honeycomb structural body in the unified Structure to form. This allows the ceramic Honeycomb structural body has a smaller number of defects and excellent dimensional precision with increased thermal shock resistance having.

at such a method for producing the ceramic honeycomb structural body For example, the step of forming the processed ceramic honeycomb body preferably be carried out by providing a Holding and rotating device for holding the processed ceramic Honeycomb body at both ends, turning the processed ceramic honeycomb body during operation of the holding and rotating device with a blade or a squeegee, which is at a distance of a surface of the processed ceramic honeycomb body arranged to define a particular gap, and providing an outer wall-forming material application device, to cause the outer wall-forming material by the particular gap flows to the outside circumferential extent of the processed ceramic honeycomb body to get upset.

at such a manufacturing process allows use the blade or squeegee that the outer wall-forming Material on the outer circumferential circumference of the processed ceramic honeycomb body in an extremely uniform pattern is applied.

at the method for producing the ceramic honeycomb structural body For example, the step of forming the outer wall may be preferred repeated application of the outer wall-forming material on the outer circumferential circumference of the processed ceramic honeycomb body and performing leveling the step of applying the outer wall-forming material include.

at such a manufacturing method, the outer wall in be formed more uniform thickness, causing the formation the ceramic honeycomb structural body with a smaller Number of defects is allowed while he has excellent dimensional precision and increased thermal shock resistance.

In the method for producing the ceramic honeycomb structural body, the step of machining the peripheral edge portion may preferably include rotating the calcined ceramic honeycomb body so that an outer circumference of the calcined ceramic honeycomb body may be determined with a predetermined diameter The peripheral speed rotates, rotating a diamond grindstone-finished grindstone in contact with the outer wall of the calcined ceramic honeycomb body, and feeding the grindstone at a predetermined feeding speed to grind and remove the peripheral edge portion of the calcined ceramic honeycomb body.

at Such a manufacturing process is free from the risk of error Processing like a chipping result or the like in the middle the processing of the calcined ceramic honeycomb body. Therefore, it becomes possible to have a ceramic honeycomb structural body with a lower number of defects while receiving he excellent dimensional precision and increased Thermal shock resistance has.

at the method for producing the ceramic honeycomb structural body can the step of making the compact ceramic honeycomb body Preferably, the use of the mold comprising a recess portion in order to form the partitions, in the absence a recess portion to form the outer wall.

at such a manufacturing method, the compact ceramic honeycomb body are formed in a structure that only the partitions having no outer wall formation. As the outer wall on the compact ceramic honeycomb body is not present, there is no non-uniform formation of the outer wall thickness, which is reflected as an origin causing one Cracking occurs, thereby minimizing the occurrence of cracking becomes. In the compact ceramic honeycomb body used in the absence of the outer wall without the appearance of cracks is formed, only a bent cell portion of the calcined ceramic honeycomb body aimed at the step the processing of the outer peripheral edge region of the calcined ceramic honeycomb body subjected to after the calcination step has been performed. This allows a remarkable reduction in the the processing time required while a notable decrease in uneconomical use of Material that needs to be manufactured and removed is achieved.

Brief description of the drawings

1 Fig. 10 is a flow chart showing a method for producing a ceramic honeycomb structural body according to the present invention.

2 FIG. 12 is a structural view partially showing a cross-sectional view of a step of forming the ceramic honeycomb structural body of a first embodiment according to the present invention. FIG.

3A Fig. 15 is a perspective view of a compact ceramic honeycomb body showing an outer peripheral wall with a risk of defects occurring therein, which is manufactured for the first embodiment according to the present invention.

3B Fig. 10 is a typical cross-sectional view showing how a crack and bent cells are generated in the ceramic honeycomb structural body.

4A FIG. 12 is a view showing an outline of a processing step performed in the first embodiment according to the present invention. FIG.

4B Fig. 15 is a typical cross-sectional view showing a processed ceramic honeycomb body subjected to the processing step carried out in the first embodiment according to the present invention.

5 Fig. 16 is a perspective view showing an outline of an outer wall forming step to be carried out in the first embodiment according to the present invention.

6A Fig. 14 is a typical view showing a first filled outer wall body formed in the first embodiment according to the present invention.

6B Fig. 12 is a typical cross-sectional view showing a state under which the first filled outer wall body is kept in a stationary state.

6C is a perspective view of a surface state of the first filled outer wall body, which is left in the stationary state.

7A Fig. 14 is a typical view showing a second filled outer wall body formed in the first embodiment according to the present invention.

7B FIG. 12 is a perspective view of a surface state of the second filled outer wall body left in the stationary state. FIG.

8th Fig. 14 is a typical cross-sectional view showing the ceramic honeycomb structural body obtained after the simultaneous sintering step carried out in the first embodiment according to the present invention.

9 FIG. 15 is a view showing a crack incidence rate against a relative sintering change rate curve showing an effect obtained by the first embodiment according to the present invention as compared with an effect of a comparative example. FIG.

10A Fig. 12 is a fragmentary front view showing an outline of an outer wall-forming device to be used in a second embodiment according to the present invention.

10B is a cross-sectional view showing the in 10A shown outer wall-forming device shows.

11A Fig. 13 is a view showing an outline of a mold used for the first embodiment.

11B Fig. 16 is a view showing an outline of a mold used for the third embodiment according to the present invention.

12 FIG. 4 is a typical view showing an overview of a compact ceramic honeycomb body identical to that in FIG 11B shown molding tool is extruded.

13 Fig. 13 is a characteristic diagram showing a thermal change in the CTE (coefficient of thermal expansion) of cordierite.

Detailed description preferred embodiments

Now is a method for producing a ceramic Honeycomb structural body according to the present invention Invention with reference to various in the accompanying drawings shown embodiments described. However, that is the present invention should not be construed as referring to those below described embodiments is limited and technical concepts of the present invention can in combination with other known technologies or the other Technology, the equivalent functions with such known Technologies.

First Embodiment

A method for producing a ceramic honeycomb structural body of a first embodiment according to the present invention will be described below in detail with reference to FIG 1 described. 1 Fig. 10 is a flow chart illustrating an outline of various steps constituting the method of manufacturing the ceramic honeycomb structural body of the first embodiment according to the present invention.

When in 1 shown raw material mixing step P1 are blended raw materials in a particular ceramic composition. In the kneading step P2, a mixture of the blended raw materials mixed with a certain particle size distribution, a dispersion medium such as water or the like and a certain auxiliary agent or the like is kneaded to thereby form a ceramic clay.

At the Toneinstellschritt P3 will the fluidity of the ceramic Tons set and, in the forming step P4, the ceramic clay pressed from a specific mold to a compact ceramic honeycomb body to form, with a large number of with partitions defined cells is formed.

At the Drying step P5 becomes the compact ceramic honeycomb body dried appropriately, followed by the calcination step P6 performed is added to the dried compact ceramic honeycomb body Calcine at a certain temperature, which is less than one Sintering temperature is, thereby a calcined ceramic To form honeycomb body.

In the outer circumferential processing step P7 becomes an outer circumferential edge of the calcined processed ceramic honeycomb body in a specific profile, using a processing device, whereby a processed ceramic honeycomb body is obtained.

At the Outside wall material adjusting step P80 becomes an outer wall-forming Material produced in the same composition, according to the Sintering step appears, as the blended raw materials and having a certain rate of sintering change, different from that of the processed ceramic honeycomb body is.

At the Outside wall forming step P8 becomes the outside wall-forming Material uniform to the outer circumferential Surface of the processed ceramic honeycomb body applied to thereby form an outer wall thereon.

At the Drying step P9 becomes the processed ceramic honeycomb body and the outside wall, on the outside circumferential surface of the processed ceramic honeycomb body is applied, dried appropriately. After that, at the same time Sintering step P10, simultaneous sintering is performed to allow that the outer wall and the processed ceramic honeycombs in the structure unified become.

According to the present invention leads to the calcination of the compact ceramic honeycomb body to the formation of the calcined ceramic honeycomb body with increased strength, withstand the processing step. Therefore, it becomes possible Defects such as cracking caused during the molding step, bent cells and by the own weight of the calcined ceramic honeycomb body caused asymmetric sections to be removed by processing. In addition, the calcined ceramic honeycomb space to one during the Sintering caused dimensional change. This minimizes the leakage of stress caused by a difference caused by a dimensional change, that from the step of sintering the on the outside circumferential surface of the processed ceramic honeycomb body formed outer wall results. In addition, you can the processed ceramic honeycomb body and the outer wall be sintered in a unified structure. Therefore, will it is possible to have a ceramic honeycomb structural body with a lower number of defects while receiving he excellent dimensional precision and increased Thermal shock resistance has. About that In addition, in the outer wall forming step P8, the outer wall on the outer circumferential surface of the processed ceramic honeycomb body in several Steps are formed while a viscosity characteristic of the outer wall-forming material is adjusted.

The method for producing the ceramic honeycomb structural body 1 _CFD The first embodiment according to the present invention will be described below with reference to a concrete exemplary trap as applied to the ceramic honeycomb structural body 1 _CFD (with parameters such as a bulkhead thickness: 15 mil, cell density: 250 cpsi, outer diameter: φ200 mm, outer wall thickness: 40 mil, length: 200 mm, and porosity: 50%) of cordierite quality for use as a diesel particulate filter ( DPF) installed in a combustion exhaust passage of a diesel engine to trap particulate matter PM. Advantageous effects of the present invention will be described in relation to various problems encountered in the prior art manufacturing process.

In the raw material blending step P1, examples of the blended raw materials include raw materials having a cordierite yield composition (2MgO.3Al ₂ O ₃ .H ₂ O) on sintering. That is, these raw materials include ceramic raw material powder that are suitable selected from the group consisting of talc 3MgO · 4SiO ₂ · H ₂ O, magnesia MgO, silicon dioxide SiO _2, kaolin Al ₂ O ₃ · 2SiO ₂ · 2H ₂ O, aluminum oxide Al ₂ O ₃ , bohemite AlOOH and aluminum hydroxide Al (OH) ₃ , etc. The ceramic raw material powders are blended in a certain blending ratio to provide a blended raw material having a certain particle size distribution. In addition, depending on the needs, the ceramic powders may further include yttria Y ₂ O ₃ , titanium oxide TiO ₂ and transition metal, etc.

In the subsequent kneading step P2, auxiliaries are added to the mixed raw material. Examples of the excipients include a binder, a plasticizer, a dispersing agent, a lubricant, a peptizer, a surfactant and a pore-forming agent, etc., such as methylcellulose MC, carboxymethylcellulose CMC, polyvinyl alcohol PVA, starch glue, polyalkylene derivatives, glycerin, gelatin, wax emulsion, carbon and Sawdust, etc. Among them, suitable materials are selected and kneaded with the blended raw material to thereby make the ceramic clay 100 to build.

In the clay adjustment step P3, a moisture rate and viscosity of the ceramic clay become 100 set to set ceramic tone 100 to obtain with a certain flow characteristic.

In the subsequent forming step P4, as in 4 shown is set ceramic clay 100 through a mold 2 extruded, formed with a particular lattice-like recess pattern, using a plunger-type or helical extrusion machine 3 , thereby successively forming a compact ceramic honeycomb body which becomes a transfer device 4 such as a conveyor belt or the like is supplied. The compact ceramic row-shaped honeycomb body has an outer wall 10 _FDM on, in which a plurality of partitions 11 _FMD are formed to a large number of cells 12 _FMD define. The compact ceramic row-shaped honeycomb body is then cut to a certain length using a cutting device 5 at a stage before and after the drying step, thereby forming a compact ceramic honeycomb body 1 _FMD to build.

In general, the ceramic clay 100 a non-Newtonian liquid that does not have a laminar flow in the as in 2 shown extrusion machine 3 forms and has a relatively limited velocity distribution. That is, during a stream of the ceramic clay 100 who the extrusion machine 3 flows through, becomes the ceramic clay 100 in frictional contact with an inner circumferential wall of the extrusion machine 3 held. This causes a localized area of the ceramic clay 100 at a circumferential position near the inner circumferential wall of the extrusion machine 3 which is at a lower flow rate than that of the other portion of the ceramic clay 100 in the middle of the extrusion press 3 emotional. During the movement of the mold 2 extruded ceramic clay 100 It is likely, due to an impairment caused by such a velocity distribution, that the outer wall 10 _FMD has localized areas that are made with a thinner wall thickness.

In the compact ceramic body 1 _FMD with the outer wall 10 _FMD Made with such a thinned wall area, there is a risk of fine cracks 13 _FMD standing on a surface of the outer wall 10 _FMD in an in 3A and in a frame A of 3B shown manner occur. These fine cracks 13 _FMD act as origins (starting points) that cause a risk of cracking that grows large when subjected to sintering.

Furthermore, because of the compact ceramic honeycomb body 1 _FMD Immediately after molding is soft in its structure and the partitions 11 _FMD are extremely thin in thickness. Therefore, if a lower part of the compact ceramic honeycomb body 1 _FMD is placed in a furnace support (not shown) in contact therewith for supplying, then it is for the lower part of the compact ceramic honeycomb body 1 _FMD the risk that he bent cells 14 _FMD which is characterized by its own weight of in a frame B in 3B shown compact ceramic honeycomb body 1 _FMD arise.

The resulting compact ceramic honeycomb body 1 _FMD is then subsequently dried in the drying step P5, by using a microwave drying apparatus or the like, and further, the compact ceramic honeycomb body becomes 1 _FMD calcined in the calcination step P6 at a temperature lower than the sintering temperature.

In the present embodiment, the calcining temperature is selected to be at a value ranging from 1360 ° C to 1400 ° C. This causes the compact ceramic honeycomb body 1 _FMD initiate a cordierite phase in a three-component system of MgO-SiO ₂ -Al ₂ O ₃ . Thus, such a calcination temperature enables the compact ceramic honeycomb body 1 _FMD is not completely sintered, leaving room to allow for a dimensional change during sintering. During the progress of the calcining step, organic substances disappearing to the compact ceramic honeycomb body disappear 1 _FMD as an aid, and a solid state reaction occurs in MgO-SiO ₂ -Al ₂ O ₃ components contained in the raw materials to start the formation of a cordierite phase, thereby producing a calcined ceramic honeycomb body 1 _FMD is obtained.

In the outer peripheral circumferential processing step P7, an outer circumferential edge is formed the resulting calcined ceramic honeycomb body 1 _PRE ground, creating a processed ceramic honeycomb body 1 _SPD is obtained. The calcined ceramic honeycomb body 1 _PRE has a greatly increased mechanical strength over that of the compact ceramic honeycomb body 1 _FMD but has a lower bond strength between the particles than that of the particles of the sintered compact ceramic honeycomb body 1 _FMD , Therefore, it is easy to use the outer circumferential periphery of the calcined ceramic honeycomb body 1 _PRE to process. Around the outer circumferential edge of the calcined ceramic honeycomb body 1 _PRE to grind, an in 4A shown NC outer periphery grinding machine 6 used. The NC outer circumference grinding machine 6 includes a grindstone 6a disc having an outer peripheral surface finished with diamond grindstones which is in contact with the outer peripheral edge of the calcined ceramic honeycomb body 1 _PRE is brought while it rotates at a certain rotational speed (for example, 100 to 7000 rpm). In this case, the calcined ceramic honeycomb body becomes 1 _PRE rotated to cause an outer circumference to have a certain peripheral speed (of, for example, 630 to 4400 m / min). When grinding, the grindstone becomes 6a moved to the outer circumferential edge of the calcined ceramic honeycomb body 1 _PRE to grind at a certain processing speed (of, for example, 500 mm / min).

The calcined ceramic honeycomb body 1 _PRE has a certain grinding allowance AR _SP (of, for example, 7 mm equivalent to a total of five cells) to result in a particular processed outer circumferential surface L _sp being determined in consideration of a dimensional change imposed on the calcined body during sintering is allowed.

at the sintered body, in the process of the associated Prior art is processed, the sintered body hard in the structure and therefore creates the need for the sintered body to reduce a grinding allowance as small as possible. In the manufacturing process, the The present invention, on the contrary, the calcined ceramic honeycomb bodies in one stage subjected to the calcining step of the processing. Therefore, can The calcined ceramic honeycomb body simply ground and allows to ensure an adequate grinding allowance. Therefore, it may have broken parts like the bent cells or cracks reliably remove.

The cracks 13 _PRE and the bent cells 12 _PRE are from the calcined ceramic honeycomb body 1 _PRE , as in 4B shown removed, whereby a processed ceramic honeycomb body 1 _SPD is obtained from a variety of cells 12 _PRE exists only with non-deformed partitions 11 _PRE are defined. In addition, the processed ceramic honeycomb body 1 _SPD a surface area open cell 12 _OPN is formed, which open in the direction of the surface area.

The outer wall forming step P8 includes a holding and rotating device 7 a pair of disc holders 7a and 7b between which the processed ceramic honeycomb body 1 _SPD at both ends as in 5 is shown shown. The holding and rotating device 7 drives the disc holders 7a and 7b to the processed ceramic honeycomb body 1 _SPD to turn. Meanwhile, a material feed section allows 15 as a container, which is an outer-circumferential wall-forming material 150 to an outer circumferential periphery of the processed ceramic honeycomb body 1 _SPD is supplied during the rotation thereof. Therefore, the outer wall-forming material 150 on the outer circumferential periphery of the processed ceramic honeycomb body 1 _SPD be applied. During such application, a film thickness compensation device 8th like a squeegee or a blade, etc. a cutting edge 8a which is spaced from the processed outer peripheral surface by a certain gap GP. This allows the excess outer wall-forming material 150 is removed while causing the outer wall-forming material 150 in the open cells 12 _OPN is introduced. Therefore, the processed ceramic honeycomb body 1 _SPD with an outer wall 151 with a certain film thickness (of, for example, 0.3 to 2 mm) as in 6A shown to be formed.

In the outer wall-forming material 150 For example, the outer wall material adjusting step P80 is performed to prepare a cordierite yield material, a dispersing agent, a binder, a viscosity and elasticity adjusting agent, etc. and a dispersion medium such as water. These materials are blended and adjusted in a pulp or paste state in a mixture having the same composition as that of the calcined ceramic honeycomb body 1 _PRE as it appears after the sintering step.

Further For example, the outside wall forming step P8 may be in a plurality of split form operations.

When the outer wall-forming material 150 on the surface of the processed ceramic honeycomb body 1 _SPD once to form the outer wall 151 is applied, whereby a first filled outer wall body 1 _CDT , as in 6A shown, then the outer wall-forming material 150 not appropriate in the open cells 12 _OPN be filled in a uniformly distributed pattern. This causes a risk of empty spaces or unfilled gaps VC that are in the open cells 12 _OPN of the processed ceramic honeycomb body 1 _SPD are scattered.

Furthermore, the stationary placement of the first filled outer wall body 1 _CTD to allow the outer wall 151 the leveling is subjected to an effect of causing that part of the outer wall 151 flows into the unfilled gaps VC, so that unfilled gaps VC can be filled with the outer wall-forming material. This allows for a resting filled outer wall body 1 _STLD is formed in a structure having a surface at risk of circumferentially spaced concave or notched areas 152 which, as in 6C shown on the outside wall 151 be formed. The concave or notched areas 152 have a thin film thickness and extend in longitudinally striped recesses extending in an extrusion direction.

Therefore, as in 7 shown, allows further application of the outer wall-forming material 150 on a surface of the resting filled outer wall body 1 _STLD , the notched areas 152 to refill and a second outer wall 123 forming a second filled outer wall body 1 _WCTD with a smooth, round surface, as in 7B shown is formed.

The open cells 12 _OPN formed on the processed outer circumferential surface L _{sp of} the processed ceramic honeycomb body 1 _SPD occur, have opening shapes that are not necessarily formed in a uniform pattern. Therefore, if so, to form the first filled outer wall body 1 _CDT used exterior wall-forming material 150 has a high viscosity, then there is a likelihood of a risk that a difficulty will occur, the open cells 12 _OPN with the outer wall-forming material 150 to fill adequately. Therefore, this must be for forming the first filled outer wall body 1 _CDT used exterior wall-forming material 150 while the outer wall material adjusting step P80 is preferably set to a low viscosity. In addition, the notched areas 152 relatively shallow at a radial depth and can easily with the outer wall-forming material 150 in a unified film thickness even in the presence of high viscosity. Therefore, this must be done to form the second filled outer wall body 1 _WCDT used exterior wall-forming material 150 preferably be set to a high viscosity.

When completely forming the outer wall 151 becomes the outer wall 151 in the drying step P9 using a microwave drying device or the like appropriately dried. Thereafter, at the simultaneous sintering step P10, the first filled outer wall body becomes 1 _CDT and the second filled outer wall body 1 _WCDT subjected to simultaneous sintering at a certain sintering temperature, thereby causing the outer wall 151 and the partitions 11 _PRE be sintered simultaneously in a unified structure. Therefore, the ceramic honeycomb structural body 1 _CFD with an outer wall 15 _CFD in which a large number of cells 12 _CFD with partitions 11 _CFD are split, with all the component parts in a completely unified structure, as in 8th shown to be formed.

Also in the present invention, the simultaneous sintering temperature set to a value ranging from 1430 to 1450 ° C.

The manufacturing method of the present invention has various advantageous effects, as described in detail below with reference to Tables 1 and 2 and 9 described.

A compact ceramic honeycomb body of the related art was sintered intact for Comparative Example 1 with a crack rate indicated in Table 2. Compact ceramic honeycomb bodies were prepared as specimens for Examples 1-3 for the first embodiment according to the present invention. In such a manufacturing process, the outer wall-forming materials become 150 in compositions used to have different sintering change rates S _SKN so that outer walls having varying film thicknesses were formed, with cracking rates indicated in Table 1 as such of Examples 1 to 3. [Table 1] Film thickness (mm) Relative sintering change rate (%) -0.25 0 0.25 0.5 0.75 example 1 0.9 D C A A A Example 2 1.4 A A A A A Example 3 1.9 A A A A A

As shown in Table 1, it has been shown that when the outer wall 151 has a thin film thickness, then there is a risk that a crack just in the outer wall 151 occurs. Although increasing the film thickness of the outer wall 151 leads to an effect of preventing the occurrence of cracking, has the outer wall 151 an increased heat capacity. Therefore, when applying the ceramic honeycomb structural body, the outer wall 151 reduce the wall thickness as low as possible. For this purpose, the ceramic honeycomb structural body with the outer walls 151 The ceramic honeycomb structural bodies, which are formed with the outer walls in each case, are manufactured in many split steps 151 are each prepared in a single application step, with crack incidence rates of Example 4, are shown in Tables 2 and 9 displayed as example 4. Other ceramic honeycomb structural bodies were made in structures with the outer walls 151 each formed by two application steps, with crack incidence rates shown in Table 2 and 9 than those of Example 5 are displayed. [Table 2] Number of coating steps Sintering rate of change (%) Crack incidence rate Example 4 1 -0.5 C 1 0 C 1 0.5 B 1 1 B Example 5 2 -0.5 B 2 0 A 2 0.5 A 2 1 B Comparative Example 1 - 0 D

In Tables 1 and 2, a symbol "A" represents the crack incidence rate which is at a minimum value with the best results; "B" represents the rate of crack incidence that at an advantageous value at a good result; "C" the crack rate, which is at a mean value at a normal result; and "D" the crack incidence rate, that at a defective one and unacceptable result.

It has been found that the crack incidence rate decreases when the outer wall-forming material 150 has a relative sintering change rate ΔS between a calcined body sintering change rate S _BOD and an outer wall sintering change rate S _SKN to satisfy the relationship defined in the following expressed formula 1. -1.5 ≤ ΔS ≤ 0.5 Formula 1 in which ΔS = S BOD - p SKN (%) S BOD = 100 · D CFD / D PRE (%) S SKN = 100 · T CFD / T CTD (%) where S _{BOD is} the calcined body sintering change rate of the calcined ceramic honeycomb body subjected to the sintering step 1 _PRE which is calculated by dividing a dimension D _CFD of the calcined body subjected to the sintering step 1 _PRE by a dimension D _{PRE of} the calcined body 1 _PRE at a stage prior to the sintering step to represent an index representing a calcined body sintering change of the calcined ceramic honeycomb body 1 _PRE indicates when it is subjected to the sintering step; and S _SKN represents an outer wall sintering change rate obtained by dividing a film thickness dimension T _{CFD of} the outer wall 151 following the sintering step, through a film thickness dimension T _{CTD of} the outer wall 151 at a stage prior to the sintering step to represent another index indicating a sintering change of the outer wall 151 indicates when it is subjected to the sintering step.

The outer wall sintering change rate S _{SKN of} the outer wall-forming material 150 can be adjusted by regulating a grain size distribution of the ceramic raw material for the outer wall-forming material 150 and varying a kind of starting raw material and a concentration of the slurry or the like with base materials having the same composition as that of the ceramic raw material containing the compact ceramic honeycomb body 1 _FMD forms.

In the present invention, among these starting raw materials, the raw materials are set in a blending ratio to form an aluminum source Al, whereby the outer wall sintering change rate S _{SKN of} the outer wall-forming material 150 is set.

Second Embodiment

A method for producing a ceramic honeycomb structural body of a second embodiment according to the present invention will be described below with reference to FIG 10A and 10B which show an outer wall former used for carrying out an outer wall forming step which is part of the present manufacturing method.

The manufacturing method of the present embodiment includes substantially the same steps as those of the manufacturing method of the first embodiment except for the step of forming an outer wall on an outer circumferential periphery of a calcined ceramic honeycomb body in a further uniform manner. A ceramic honeycomb structural body to be obtained in the present embodiment may not only take the form of a columnar shape but also an elliptic or oval shape, a rectangular shape and a polygonal shape, etc., which may be suitably selected depending on the needs. In order to satisfy such a changed profile, the molding step P4 is replaced by replacing the molding tool 2 with another mold for forming a compact ceramic honeycomb body to form a compact ceramic honeycomb body of such a desired profile. Further, during the outer circumferential wall processing step P7, the use of the NC grinding machine enables 6 the outer wall of the calcined ceramic honeycomb body 1 _PRE to grind in any profile.

In the present embodiment, a holding and rotating device 7A and an outer wall unit forming device 8A , as in 10A and 10B shown used to an exterior wall 151A on an outer circumferential periphery of an oval shaped processed ceramic honeycomb body 1 _SPDA to form in a uniform wall thickness. Therefore, the present embodiment differs from the manufacturing method of the first embodiment in this respect.

10A is a fragmentary front view showing a holding and rotating device 7A and an outer wall unit forming device associated therewith 8A shows. 10B is a side view showing these devices. As in 10A and 10B shown, includes the holding and rotating device 7A a holding and rotating section 70a Being operational, the processed ceramic honeycomb body 1 _SPDA to hold and rotate, and a lifting and lowering mechanism 71A Being ready, the processed ceramic honeycomb body 1 _SPDA to move. Therefore, the processed ceramic honeycomb body 1 _SPDA be controlled to rotate while being movable in a vertical direction, and the outer wall 151A can on the surface of the processed ceramic honeycomb body 1 _SPDA be formed in any profile.

Further, the outer wall unit forming apparatus includes 8A a storage tank 81 for storing the outer wall-forming material 150 and a movable blade 80 that are inside the store tanks 81 is arranged, with a lower edge portion 80a pointing in the direction of an outlet opening 81a the storage tank 81 is aligned to be vertically movable. With the movable blade downwards 80 becomes the lower edge section 80a the movable blade 80 moved to a position to a certain gap GP between a cutting edge of the lower edge portion 80a and an outer periphery of the processed ceramic honeycomb body 1 _SPDA provide. In the processed ceramic honeycomb body 1 _SPDA which is rotated in a counterclockwise direction as shown by an arrow CCW while being moved in the vertical direction as shown by an arrow V1 becomes the outer wall-forming material 150 that from a dispensing opening 81a the storage tank 81 is supplied to an outer circumferential surface of the processed ceramic honeycomb body 1 _SPDA applied with a certain film thickness. After the outer wall 151A is formed, becomes a closure 82 moved down to a supply of the outer wall-forming material 150 to block.

Third Embodiment

A method for producing a ceramic honeycomb structural body of a third embodiment according to the present invention will be described below with reference to FIG 11A and 11B and 12 described.

The manufacturing method of the present embodiment includes substantially the same steps as those of the manufacturing method of the first embodiment except the forming step P7 with the use of a mold 2A with the intention of achieving notable cost reductions in material cost and out-of-scope processing step P4.

In the first and second embodiments set forth above, exemplary cases have been described above with reference to the structures wherein the ceramic honeycomb structural body 1 was formed with the outer wall and the intermediate walls, both of which were formed simultaneously, by using the molding tool 2 with an outer circumferential wall-forming recess portion 210 and an intermediate wall-forming recess portion 211 that like in 11A shown are formed.

In contrast, in the present embodiment, a compact ceramic honeycomb body becomes 1A extruded in a structure that only partitions 11 _FMD having, using the molding tool 2A that only has a partition wall education section 211 in the absence of the outer circumferential wall-forming recess portion 210 has, as in 11B shown.

As in 12 shown has the compact ceramic honeycomb body 1A from such a structure an outer circumferential periphery with a risk of bent cells 14a on, at a lower end 1aa of the outer circumferential periphery, such as those encountered in the above-mentioned embodiments. Since the ceramic honeycomb structural body 1A as in a frame B of 12 As shown in FIG. 2, having no outer circumferential portion, a non-uniform wall thickness causing a crack initiation start point is present in the outer circumferential wall, with less susceptibility to causing the occurrence of a crack. The outer circumferential wall is absent with the elimination of the crack, and therefore, the outer circumferential wall processing step P7 performed after the calcining step need only be in an area around the bent cells 14a to be removed for removal. This allows a remarkable reduction in the time required for the processing step, with a remarkable decrease in uneconomical use of raw materials to be removed in processing.

13 FIG. 12 is a graph showing an offset (%) of the processed ceramic honeycomb body with respect to a sintering temperature of a cordierite yield material used in the method of producing the ceramic honeycomb structural body of the first embodiment according to the present invention.

In 13 S _{BOD represents} the offset of the processed ceramic honeycomb body 1 _SPD and S _SKN represents the offset of the filled outer wall body 1 _CDT represents.

Further, the present invention is not limited to the particular features of the various embodiments as described above, and the present invention can be embodied in various other modifications and transformations. For example, the calcining temperature and the sintering temperature may be appropriately selected in accordance with the characteristics of the ceramic raw materials used. In addition, the present invention can be applied to methods for producing ceramic honeycomb structural bodies using not only the cordierite, but also Also, various other ceramic materials such as those containing oxides, nitrides or carbonates, etc., such as alumina, titania, silicon nitride and silicon carbide, by adjusting a sintering change rate of calcined ceramic honeycomb formed from such materials and a sintering change rate of an outer wall-forming material.

The ceramic honeycomb structural body based on those described above Can be obtained, for example, applied be on a support body of an exhaust gas purification catalyst of a Motor vehicle or a filter base material for particulate matter trap. In such applications, each of the ceramic honeycomb structural bodies has both ends in an alternating pattern using the plugged the same material, the same quality such as those used for the outer wall ceramic material in a stage before or after the outer wall was formed. Subsequently, the plugged Sections and the ceramic honeycomb body at the same time be sintered.

While the specific embodiments of the present invention described in detail, it will be understood by those skilled in the art, that various modifications and alternatives to such details developed in the light of the general teaching of the Revelation can be. Accordingly, those disclosed are particular To understand arrangements so that they only illustrate and not limit the scope of the present invention, which in its full breadth of the following claims and all equivalents thereof.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - JP 3-275309 [0003]

Claims (7)

A method of producing a ceramic honeycomb structural body having a nearly cylindrical outer periphery divided with partitions formed in a certain profile to form a plurality of cells acting as gas flow passages, the method comprising the steps of: kneading a mixture of a certain ceramic material and a specific auxiliary agent to produce a kneaded molding material ( 100 ) to build; Forming a compact ceramic honeycomb body ( 1 _FMD ) by extruding the kneaded molding material through a molding tool ( 2 . 2A ) with a particular grid-like recess pattern; and calcining the compact ceramic honeycomb body at a temperature lower than a sintering temperature to form a calcined ceramic honeycomb body ( 1 _PRE ) to build; characterized by: processing a circumferential edge region of the calcined ceramic honeycomb body ( 1 _PRE ) used to form a processed ceramic honeycomb body ( 1 _SPT ) is to be removed; Forming an outer wall ( 151 . 23 ) on an outer circumferential periphery of the processed ceramic honeycomb body by applying thereto an outer wall-forming material ( 150 ); and simultaneously sintering the outer wall and the processed ceramic honeycomb body to thereby form the ceramic honeycomb structural body (10). 1 _CFD ) in a unified structure. A method for producing the ceramic honeycomb structural body according to claim 1, characterized in that: the outer wall-forming material ( 150 ) is used in a slurry state or a paste state when mixing a ceramic raw material, a dispersing agent, a binder, and a viscosity and elasticity adjusting agent, wherein the ceramic raw material has the same basic composition, if is subjected to the sintering step, such as the ceramic material. A method for producing the ceramic honeycomb structural body according to claim 1, characterized in that: the outer wall-forming material ( 150 ) has a relative sintering change rate ΔS between a calcined body sintering change rate S _BOD and an outer wall sintering change rate S _SKN to satisfy the relationship defined in the following expressed formula 1. -1.5 ≤ ΔS ≤ 0.5 Formula 1 in which ΔS = S BOD - p SKN (%) S BOD = 100 · D CFD / D PRE (%) S SKN = 100 · T CFD / T CTD (%) wherein S _{BOD is} the calcined body sintering change rate of the calcined ceramic honeycomb body subjected to the sintering step ( 1 _PRE ) which is calculated by dividing a dimension (D _CFD ) of the calcined body subjected to the sintering step ( 1 _PRE ) by a dimension (D _PRE ) of the calcined body ( 1 _PRE ) at a stage before the sintering step to represent an index showing a calcined body sintering change of the calcined ceramic honeycomb body ( 1 _PRE ) when subjected to the sintering step; and S _SKN represents the outer wall sintering change rate obtained by dividing a film thickness dimension (T _CFD ) of the outer wall (FIG. 151 ) following the sintering step, by a film thickness dimension (T _CTD ) of the outer wall ( 151 ) at a stage before the sintering step to represent another index indicating a sintering change of the outer wall ( 151 ) when subjected to the sintering step. A method of manufacturing the ceramic honeycomb structural body according to claim 1, characterized in that: the step of forming the processed ceramic honeycomb body is performed by providing a holding and rotating device (FIG. 7 ) for holding the processed ceramic honeycomb body at both ends thereof, rotating the processed ceramic honeycomb body during operation of the holding and rotating device with a blade or a squeegee (US Pat. 8th . 8A ) arranged at a distance from a surface of the processed ceramic honeycomb body to define a certain gap (GP), and Be providing an outer wall-forming material application device ( 15 . 81 ) to cause the outer wall-forming material ( 150 ) flows through the specific gap to access the surface of the processed ceramic honeycomb body ( 1 _SPD . 1 _SPDA ) to be applied. Process for producing the ceramic honeycomb structural body according to claim 1, characterized in that: the step of forming the outer wall repeating the application of the Exterior wall-forming material on the outside circumferential extent of the processed ceramic honeycomb body and performing leveling after the applying step of the outer wall-forming material. The method of manufacturing the ceramic honeycomb structural body according to claim 1, wherein: the step of machining the peripheral edge portion comprises rotating the calcined ceramic honeycomb body so that an outer periphery of the calcined ceramic honeycomb body rotates at a certain peripheral speed; Gritstone finished with diamond abrasive grains ( 6 ) in contact with the outer wall of the calcined ceramic honeycomb body, and feeding the grindstone at a predetermined feeding speed to grind and remove the peripheral edge portion of the calcined ceramic honeycomb body. A method of manufacturing the ceramic honeycomb structural body according to claim 1, characterized in that: the step of forming the compact ceramic honeycomb body includes using the forming tool ( 2A ) comprising a recess portion ( 221a ) to form the partition walls, in the absence of a recess portion to form the outer wall.