JP2008133133A - Conveying device, and manufacturing method of honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveying device capable of supplying wet mixture of constant quality to a subsequent process with a small rate of a change in water content in the wet mixture before and after a conveying process, and capable of preventing generation of a crack and cell shortage on an extruded molded body especially when used in a manufacturing process of a honeycomb structure. <P>SOLUTION: The conveying device is provided with a conveying part with a conveyer for conveying the wet mixture arranged, and the rate of the change in the water content in the wet mixture before and after conveyance is not more than 3%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a conveying apparatus and a method for manufacturing a honeycomb structure.

Recently, it has become a problem that particulates such as soot contained in exhaust gas discharged from internal combustion engines such as vehicles such as buses and trucks and construction machinery cause harm to the environment and the human body.
Thus, various honeycomb filters using a honeycomb structure made of porous ceramics have been proposed as filters for collecting particulates in exhaust gas and purifying the exhaust gas.

Conventionally, when manufacturing a honeycomb structure, for example, first, a ceramic powder, a binder, a dispersion medium liquid, and the like are mixed to prepare a wet mixture. Then, the wet mixture is continuously extruded with a die, and the extruded molded body is cut into a predetermined length to produce a prismatic honeycomb molded body.

Next, the obtained honeycomb formed body is dried using microwave drying or hot air drying, and then a predetermined cell is sealed, and either end of the cell is sealed with a sealing material layer. Then, the honeycomb fired body is manufactured by performing a degreasing process and a firing process.

Thereafter, by applying a sealing material paste to the side surfaces of the honeycomb fired bodies and bonding the honeycomb fired bodies to each other, the honeycomb fired bodies in a state where a large number of honeycomb fired bodies are bundled through the sealing material layer (adhesive layer). Create an assembly. Next, the obtained honeycomb fired body aggregate is cut into a predetermined shape such as a cylinder or an elliptical column using a cutting machine or the like to form a ceramic block, and finally, a seal is formed on the outer periphery of the ceramic block. By applying the material paste to form a sealing material layer (coat layer), the manufacture of the honeycomb structure is completed.

In such a manufacturing method, after preparing a wet mixture, it is necessary to convey this wet mixture to the extrusion machine of the next process via a conveyance apparatus.
And as a conveying apparatus which conveys a wet mixture, there exists a thing as disclosed by patent document 1, 2, for example.

JP 2002-255353 A JP-A-5-131432

However, the conventional conveying apparatus has not taken into consideration the change in the moisture content of the wet mixture before and after the conveying step.
In addition, when a storage unit for storing the wet mixture is provided in a part of the transport device, there may be a variation in the period from the introduction of the wet mixture into the transport device to the discharge to the next process.
Under such circumstances, even when a wet mixture having the same water content is put into the transport device, the transport device causes a drying due to a change in diameter or due to factors such as changes in temperature and humidity. The moisture content of the discharged wet mixture may vary, and it has been a problem that a constant quality wet mixture cannot be supplied to a subsequent process.

In particular, in the manufacture of a honeycomb structure, it is necessary to supply a wet mixture having an appropriate moisture content to an extruder, but when such a wet mixture is used, the moisture content tends to be less than the appropriate amount, The surface of the extruded molded body becomes rough (dry and dry), cracks are generated, holes or cracks are partially formed in the cell wall, or part of the cell wall continuously. In some cases, defects such as the occurrence of so-called “cell breakage” occur.
On the other hand, if the moisture content exceeds an appropriate amount, it may be difficult to maintain a certain shape until the extruded molded body is dried, and there may be a defect that the honeycomb fired body is warped. .

The present invention has been made in order to solve these problems, and is a transporting device that has a small rate of change in the moisture content of the wet mixture before and after the transport process and can supply a constant quality wet mixture to the subsequent process. In particular, when used in a manufacturing process of a honeycomb structure, a conveying device capable of preventing the occurrence of cracks, cell breakage, etc. in the extruded molded body, and the molded body extruded in the extrusion molding process An object of the present invention is to provide a method for manufacturing a honeycomb structure in which cracks, cell breakage, etc. do not occur.

That is, the transport apparatus according to the present invention includes a transport unit in which a conveyor for transporting the wet mixture is provided, and the moisture content change rate of the wet mixture before and after transport is 3% or less.

It is desirable that the transport device includes a storage unit for temporarily storing the wet mixture, and the transport unit includes a casing and a belt conveyor disposed in the casing. desirable.

Moreover, in the said conveying apparatus, it is desirable that the partition member which partitions off the inside of the said casing is arrange | positioned in the downstream edge part vicinity of the said belt conveyor.

In the method for manufacturing a honeycomb structure of the present invention, after performing a transporting process of transporting a wet mixture containing a wet-mixed inorganic powder to an extrusion molding process, a number of cells are separated in the longitudinal direction by separating the cell walls by extrusion molding. A honeycomb structure manufacturing method for manufacturing a columnar honeycomb formed body arranged side by side and firing the honeycomb formed body to manufacture a honeycomb structure made of the honeycomb fired body,
In the transporting step, the wet mixture is extruded using a transporting device provided with a transporting unit in which a conveyor for transporting the wet mixture is provided, and the moisture content change rate of the wet mixture before and after transporting is 3% or less. It is transported to a molding machine.

In the method for manufacturing a honeycomb structured body, it is preferable that the transport device includes a storage unit for temporarily storing the wet mixture.

In the method for manufacturing a honeycomb structured body, it is preferable that the transport unit constituting the transport device includes a casing and a belt conveyor disposed in the casing.

In the method for manufacturing a honeycomb structured body, it is desirable that a partition member for partitioning the inside of the casing is disposed in the vicinity of the downstream end portion of the belt conveyor constituting the transport device.

It is desirable that the moisture content after transporting the wet mixture used in the method for manufacturing the honeycomb structure is 10 to 20% by weight.

The conveyance device of the present invention can prevent the wet mixture from being dried in the conveyance step, and can reduce the moisture content change rate before and after conveyance to 3% or less. Therefore, a constant quality wet mixture can be stably supplied to a subsequent process.
In addition, when the transport device of the present invention is used, for example, as a transport device before the extrusion molding process in the honeycomb structure manufacturing process, a wet mixture having an appropriate moisture content is stably supplied to the extruder. Therefore, it is possible to prevent cracks, cell breakage, and the like from occurring in the extruded product.

In particular, in the transport device of the present invention, when a partition member that partitions the inside of the casing is used in the vicinity of the downstream end of the belt conveyor that constitutes the transport device, drying of the wet mixture in the transport device is effectively prevented. The moisture content change rate before and after the transporting process of the wet mixture can be further reduced.

Further, in the method for manufacturing a honeycomb structure of the present invention, the moisture content change rate of the wet mixture before and after the transporting process can be 3% or less, so that the wet mixture having an appropriate moisture content is stable in the extruder. Thus, cracks, cell breakage and the like can be prevented from occurring in the extruded product after the extrusion process.

Further, in the method for manufacturing a honeycomb structure of the present invention, the moisture content of the wet mixture after transportation is 10 to 20% by weight, so that there is no occurrence of cracks, cell breakage, etc., and a constant shape is maintained. An extruded product can be obtained.

First, the conveying apparatus of the present invention will be described.
The transport apparatus of the present invention includes a transport unit in which a conveyor for transporting the wet mixture is provided, and the moisture content change rate of the wet mixture before and after transport is 3% or less.
That the moisture content change rate of the wet mixture before and after conveyance is 3% or less means that the absolute value of the moisture content change rate of the wet mixture before and after conveyance is 3% or less.
FIG. 1 is a cross-sectional view schematically showing an example of the transport apparatus of the present invention.
The transport device 30 includes a casing 33 having an input port 34 for charging the wet mixture, and a transport unit 32 that transports the wet mixture, which includes a belt conveyor 35.
In the transport device 30, when a wet mixture prepared in a wet mixer (not shown) is introduced into the transport unit 32 from the input port 34, it accumulates on the belt conveyor 35 constituting the transport unit 32. It becomes.

The conveyance device 30 is configured such that a casing 33 is provided so as to cover the entire periphery of the belt conveyor 35, and the entire conveyance unit 32 can be sealed. With such a configuration, it is possible to prevent moisture contained in the air in the casing 33 from moving outside the casing 33 between the inside and the outside of the casing 33.
Therefore, when a predetermined amount of water evaporates from the wet mixture in the casing 33 and the humidity in the casing 33 is once increased, the humidity in the casing 33 can be kept high thereafter.
In this way, by introducing the wet mixture into the casing 33 while keeping the humidity in the casing 33 constantly high, the rate at which moisture evaporates from the wet mixture present in the casing 33 per unit time decreases. For this reason, the amount of water evaporated in the casing 33 is reduced, and drying of the wet mixture can be prevented.
Due to the above action, it is possible to prevent the wet mixture from drying in the transport unit 32, so that the moisture content in the wet mixture before and after the transport process is kept at 3% or less while keeping the moisture in the wet mixture, Transport can be performed.
In addition, it is desirable that the rate of change in water content before and after the transport process is low, and it is more desirable that the rate of change in water content be as close to 0% as possible.

Therefore, as shown in FIG. 1, the transport unit 32 is preferably composed of a casing 33 and a belt conveyor 35 disposed in the casing 33.
In the transfer device 30 of the present invention, the casing 33 includes a casing in which a box-shaped member is provided with a lid and a casing that is previously formed into a tubular shape.

The casing 33 is preferably made of a material having a low moisture permeability. This is because a material having a high moisture permeability cannot prevent the movement of moisture inside and outside the casing 33 and does not serve its purpose. Specifically, a metal material is desirable, and the type is not particularly limited.

A partition member 38 that partitions the inside of the casing 33 may be provided in the vicinity of the downstream end of the belt conveyor 35. The partition member 38 is attached so that its upper end can rotate by a predetermined angle about a shaft 38 a provided on the top plate surface of the casing 33.
The partition member 38 is a member that can partition the space in the casing 33 and prevent moisture from moving between the partitioned spaces. Thereby, the space in which the wet mixture exists can be partitioned more narrowly, and the humidity of the partitioned space can be kept high.
By keeping the humidity of the space where the wet mixture is present high, the amount of water evaporated from the wet mixture can be reduced, and the rate of change in the water content before and after the transport process can be further reduced.

The partition member 38 is attached so that the upper end of the partition member 38 can rotate at a predetermined angle around a shaft 38 a provided on the top plate surface of the casing 33, so that the partition member is separated by the wet mixture moving on the conveyor belt 35 a. When a force is applied to the tip of the belt 38, the partition member 38 is rotated a little around the shaft 38a in an angle direction toward the moving direction of the conveyor belt 35a, and the end of the partition member 38 contacts the surface of the wet mixture. In this state, the wet mixture can be conveyed.
If the end of the partition member 38 is in contact with the surface of the wet mixture, moisture does not move between the spaces partitioned by the partition member 38. Therefore, moisture is transferred from the wet mixture during the transportation of the wet mixture. The amount of evaporating can be reduced.

The material of the partition member 38 is not particularly limited, but is preferably a material having a low water permeability and water absorption rate. This is because a material having a high moisture permeability cannot prevent moisture from moving between partitioned spaces and does not play its role. In addition, in a material having a high water absorption rate, the moisture contained in the wet mixture is absorbed by the partition member 38 and the moisture content of the wet mixture is reduced, so that the purpose of the partition member is not achieved.
Specifically, a resin material or metal material having a low water absorption rate such as a fluororesin is desirable.

In addition, the thickness of the partition member 38 is not particularly limited, but it is desirable that the partition member 38 has a thickness that prevents moisture from passing through in consideration of the relationship with the moisture permeability of the partition member 38. The partition member 38 is preferably made of a flexible material. When a force is applied to the partition member 38 by the wet mixture moving on the conveyor belt 35a, the tip of the partition member 38 is bent, so that the partition member 38 does not hinder the movement of the wet mixture, and the surface of the wet mixture This is because the conveyance can be performed with the partition member 38 in contact.

A plurality of partition members 38 may be provided in the transport path of the wet mixture. This is because by providing a plurality of partition members 38, the space where the wet mixture exists can be further narrowed to prevent the wet mixture from being dried in the partitioned space.

The belt conveyor 35 includes a conveyor belt 35a and rollers 36a and 36b. A wet mixture (not shown) deposited on the belt conveyor 35 is continuously or intermittently directed toward the downstream side of the belt conveyor 35. Can be conveyed.
The material of the conveyor belt 35a is not particularly limited, and examples thereof include rubber, resin such as urethane, vinyl chloride, fluorine resin, and silicone resin.

Here, as shown in FIG. 1, storage portions 31 </ b> A and 31 </ b> B may be provided in the downstream portion when the belt conveyor 35 is moved.
In the transport device 30 shown in FIG. 1, since the downstream position changes depending on the rotation direction of the belt conveyor 35, storage units 31 </ b> A and 31 </ b> B are provided on both ends of the belt conveyor 35.
The storage unit 31A has a discharge port that can be opened and closed on its bottom surface. In this storage unit 31A, a fixed amount of wet mixture can be temporarily stored and a constant amount per unit time can be obtained. While being controlled, the wet mixture can be supplied from a discharge port to a process for producing a molded body by an apparatus for the next process, for example, an extruder.

Further, the storage unit 31A has an open / close plate 37 that can slide to the left and right. By closing the open / close plate 37 (the state shown in FIG. 1), the storage unit 31A Can be separated from the site.
Thereby, since the space where the stored wet mixture exists can be divided narrowly, it can prevent that the wet mixture stored in 31 A of storage parts drys. For example, when the transport device 30 is stopped and the supply of the wet mixture to the storage unit 31A is stopped, it is effective to keep the open / close plate 37 closed to prevent the wet mixture from drying.

Further, in the transport device 30, the wet mixture accumulated on the belt conveyor 35 is transported continuously or intermittently to the storage unit 31B opposite to the storage unit 31A by reversing the rotation direction of the rollers 36a and 36b. And can be stored in the storage unit 31B.
Similarly to the storage unit 31A, the storage unit 31B has a discharge port that can be opened and closed, so that a fixed amount of the wet mixture can be temporarily stored and a constant amount per unit time. The wet mixture can be fed to the apparatus for the next step while being controlled.
Moreover, the storage part 31B is provided with the opening-and-closing plate 37 similar to the storage part 31A, and can prevent the drying of the wet mixture in the storage part 31B.
Thus, since the conveyance apparatus 30 can convey and store the wet mixture in both the storage unit 31A and 31B, the conveyance unit 32 includes a distribution mechanism.
In addition, when the wet mixture is supplied by distributing to the two extruders from the conveying device 30, the amount to be distributed is adjusted by adjusting the speed of the belt conveyor 35, the driving time of each of forward rotation and reverse rotation, and the like. You can choose. In addition, what amount of the wet mixture is conveyed to which storage unit may be appropriately selected.

In the transport device 30, the storage units 31 </ b> A and 31 </ b> B can serve as a buffer. Therefore, in the wet mixer (not shown) in the previous process of the transport device 30, the mixing is continued, Even in the case where the wet mixture is charged and the operation of the subsequent steps is stopped, the state can be maintained as it is for a short time.
On the other hand, when the mixing in the wet mixer is stopped and the wet mixture is not charged into the conveying device 30 and it is necessary to supply the wet mixture to the apparatus in the next process, Continuous provision of the wet mixture to the process equipment is possible.

The conveyance device 30 illustrated in FIG. 1 is a conveyance device including a distribution mechanism, and the distribution mechanism is provided in the conveyance unit 32.
However, the configuration of the transport device of the present invention is not limited to such a configuration, and for example, it may have the following configuration.

FIG. 2 is a cross-sectional view schematically showing another example of the transport apparatus of the present invention.
The conveyance device 50 shown in FIG. 2 is a conveyance device including a conveyance unit 52 and a storage unit 51. In the conveyance device 50, the storage unit 51 is located upstream of the conveyance unit 52 in the conveyance path of the wet mixture. Is different from the conveying device 30 shown in FIG.
That is, the conveying apparatus 50 is comprised from the conveyance part 52 which conveys the wet mixture which consists of the casing 53 and belt conveyors 55A and 55B, and the storage part 51 for storing a wet mixture temporarily.
The upper surface of the casing 53 and the discharge ports 51a and 51b provided on the lower surface of the storage unit 51 communicate with each other so that the wet mixture can be introduced into the casing 53 through the discharge ports 51a and 51b.

Similarly to the conveyance device 30 shown in FIG. 1, the conveyance device 50 is configured such that a casing 53 is provided so as to cover the entire periphery of the belt conveyors 55 </ b> A and 55 </ b> B, and the entire conveyance unit 52 can be sealed. Has been. For this reason, moisture contained in the air in the casing 53 can be prevented from moving out of the casing 53, and the wet mixture can be prevented from drying in the transport unit 52. The wet mixture can be conveyed while maintaining the water content in the wet mixture so that the rate of change in the water content at 3% or less.

Further, a partition member 58 for partitioning the inside of the casing 53 may be provided in the vicinity of the downstream end of each of the belt conveyors 55A and 55B, similarly to the conveying device 30 shown in FIG. Thereby, the space where the wet mixture exists can be divided more narrowly, and the moisture content change rate of the wet mixture in the divided space can be further reduced.

Since the casing 53, the conveyor belts 155a and 155b, the shape and materials of the partition member 58 and the shaft 58a are the same as those of the transport device 30 shown in FIG. 1, the description thereof is omitted.

In the casing 53, there are disposed a belt conveyor 55A constituted by a conveyor belt 155a and rollers 56a and 56b, and a belt conveyor 55B constituted by a conveyor belt 155b and rollers 56c and 56d. The belt conveyors 55 </ b> A and 55 </ b> B are configured to be able to transport the wet mixture toward the end side of the casing 53.

The storage unit 51 has an open / close plate 57 that can slide to the left and right, and the open / close plate 57 divides the internal space of the storage unit 51 vertically by being in a closed state (the state shown in FIG. 2). can do.
And the lower part parted by the opening / closing plate 57 of the storage part 51 is equipped with two discharge ports 51a and 51b on the bottom surface thereof, for discharging the wet mixture only from one of the discharge ports. A distribution mechanism is provided.
That is, a shaft member 59b is rotatably attached to a branch portion between the discharge port 51a side and the discharge port 51b side, and one side of a plate-like switching plate 59a is fixed to the shaft member 59b. The shaft member 59b is configured to be movable at a predetermined angle in accordance with the rotation of the shaft member 59b.

When the opening / closing plate 57 is closed in such a storage unit 51, the wet mixture prepared in the wet mixer (not shown) is transferred to the upper portion of the storage unit 51 (from the opening / closing plate 57 in FIG. 2). Can be stored in the upper part).
When the introduction of the wet mixture from the wet mixer is stopped, the inlet 54 is closed by providing an opening / closing plate or the like at the inlet 54 of the wet mixture to narrow the space where the wet mixture exists. Is effective to prevent drying of the wet mixture.

Further, when the opening / closing plate 57 is pulled out to be opened, the wet mixture can be put into the casing 53 through the discharge ports 51a and 51b. Here, by arranging the switching plate 59a at a position (see FIG. 2) that closes the discharge port 51a side, the wet mixture stored on the opening / closing plate 57 can be introduced into the casing 53 from the discharge port 51b. . Furthermore, when the position of the switching plate 59a is moved and arranged at a position that closes the discharge port 51b side, the stored wet mixture can be poured into the casing 53 from the discharge port 51a.
At this time, the amount of the wet mixture discharged from the discharge port 51a or 51b can be adjusted by adjusting the opening degree of the opening / closing plate 57.
Further, the wet mixture can be dropped little by little by applying vibration with a vibrator or the like, and the amount of the wet mixture discharged from the discharge port 51a or 51b can be controlled by adjusting the strength of vibration.

Therefore, in this storage part 51, the wet mixture can be temporarily stored in the upper part by closing the opening-and-closing plate 57, and which discharge port is opened (closed) is selected by the switching plate 59a. Thus, the wet mixture can be distributed and put into the casing 53. That is, when the discharge port 51a of the storage unit 51 is opened, the wet mixture is deposited on the conveyor belt 155a, and when the discharge port 51b is opened, the wet mixture is deposited on the conveyor belt 155b. Will be.
In the storage unit 51, the switching plate 59a may be disposed at a position where neither of the discharge ports 51a and 51b is blocked, and may be put into the casing 53 from both of the discharge ports 51a and 51b.
Thus, in the transport device 50, the storage unit 51 includes a storage mechanism and a distribution mechanism.

In addition, the wet mixture deposited on the conveyor belts 155a and 155b is conveyed in a predetermined direction by the belt conveyors 55A and 55B, and then is discharged through the outlets 53a and 53b provided in the casing 53 to the next process apparatus. Will be supplied.

The transport device described so far with reference to FIGS. 1 and 2 is a transport device including a storage unit on either the upstream side or the downstream side of the transport unit, but the transport device of the present invention includes a storage unit. It may not be provided, and a storage part may be provided on both the upstream side and the downstream side of the transport part.
1 and 2, either the transport unit or the storage unit includes the distribution mechanism, but may not include the distribution mechanism, or both may include the distribution mechanism. .
Moreover, when the transport apparatus of the present invention includes a distribution mechanism, the distribution destination is not limited to two locations, and may be three or more locations.

Moreover, although the conveying apparatus shown in FIG.1 and 2 is provided with the belt conveyor which used the flat belt as a conveyor, the conveyor with which the conveying apparatus of this invention is provided is not necessarily limited to this, For example, FIG. 3-1 (a) and (b), and conveyors as shown in FIGS. 3-2 (a) and (b) may be used.

FIGS. 3-1 (a) and FIGS. 3-2 (a) are plan views schematically showing another example of the conveyor constituting the transfer device of the present invention. FIGS. 3-2 (b) is sectional drawing of each of the conveyor shown to FIGS. 3-1 (a) and FIG. 3-2 (a).
A conveyor 65 shown in FIG. 3A includes a conveyor belt 65a with a sun and rollers 66a, 66b. The conveyor belt 65a with a sun has a plate-like protrusion 65b substantially perpendicular to the traveling direction of the belt. Is provided. In addition, although not shown in figure, the conveyance part provided with the conveyor 65 is provided with the casing similar to what was shown in FIG. 1 or FIG.
The shape of the conveyor belt 65a with sun is not particularly limited. By providing the sun, the wet mixture can be transported without flowing below the sun even when the transport path is inclined.
Moreover, it does not specifically limit as a material of the conveyor belt 65a with a sun, For example, resin, such as rubber | gum, urethane, vinyl chloride, a fluororesin, a silicone resin, etc. are mentioned.

Moreover, the conveyor 75 shown to FIGS. 3-2 (a) and (b) is a chain conveyor with a bucket, is provided with the chain 75a with a bucket and the rollers 76a and 76b, and the chain 75a with a bucket has the surface of a chain. A bucket 75b for holding the wet mixture is fixed at a predetermined interval. In addition, although the conveyance part provided with the conveyor 75 is not shown in figure, it is equipped with the casing similar to what was shown in FIG. 1 or FIG.
The shape of the chain 75a is not particularly limited. By using the conveyor provided with the chain 75a, the conveyor without the meandering of the belt can be obtained even when the conveyance path is not a straight line.
Further, the shape and material of the baguette are not particularly limited. By providing the baguette, the wet mixture can be transported even when the transport path is inclined or when transport in the vertical direction is necessary.
The material of the chain 75a is not particularly limited, and examples thereof include metal materials in addition to resin materials such as rubber, urethane, vinyl chloride, fluorine resin, and silicone resin.
Such conveyors as shown in FIGS. 3-1 (a) and (b) and FIGS. 3-2 (a) and (b) are also preferably used in the conveying section constituting the conveying device of the present invention. it can.

In addition, the conveyor of the present invention uses, for example, a chain conveyor, a pallet conveyor, a trolley conveyor, a flow conveyor, a flight bearer, a disk conveyor, a power screw, a screw conveyor, etc., as a conveyor constituting the conveying unit. May be.

Next, the manufacturing method of the honeycomb structure of the present invention will be described.
In the method for manufacturing a honeycomb structure of the present invention, after performing a transporting process of transporting a wet mixture containing a wet-mixed inorganic powder to an extrusion molding process, a number of cells are separated in the longitudinal direction by separating the cell walls by extrusion molding. A honeycomb structure manufacturing method for manufacturing a columnar honeycomb formed body arranged side by side and firing the honeycomb formed body to manufacture a honeycomb structure made of the honeycomb fired body,
In the transporting step, the wet mixture is extruded using a transporting device provided with a transporting unit in which a conveyor for transporting the wet mixture is provided, and the moisture content change rate of the wet mixture before and after transporting is 3% or less. It is transported to a molding machine.

FIG. 6 is a perspective view schematically showing an example of the honeycomb structure, and FIG. 7A is a perspective view schematically showing a honeycomb fired body constituting the honeycomb structure. FIG. 7B is a cross-sectional view of the honeycomb fired body shown in FIG.

In the honeycomb structure 130, a plurality of honeycomb fired bodies 140 as shown in FIG. 6 are bundled through a sealing material layer (adhesive layer) 131 to form a ceramic block 133, and further, on the outer periphery of the ceramic block 133 A sealing material layer (coat layer) 132 is formed.
In the honeycomb fired body 140, as shown in FIG. 7B, a large number of cells 141 are arranged in the longitudinal direction, and the cell walls 143 separating the cells 141 function as a filter.

That is, in the cell 141 formed in the honeycomb fired body 140, as shown in FIG. 7B, either the inlet side or the outlet side end of the exhaust gas is plugged by the sealing material layer 142, and one cell The exhaust gas that has flowed into 141 always passes through the cell wall 143 that separates the cell 141 and then flows out from the other cell 141. When the exhaust gas passes through the cell wall 143, the particulates are separated from the cell wall 143. Captured at the part, the exhaust gas is purified.

Hereinafter, the manufacturing method of the honeycomb structure of the present invention will be described in the order of steps.
Here, a manufacturing method of a honeycomb structure when silicon carbide powder is used as the inorganic powder will be described by taking as an example a case where a honeycomb structure having a main component material of silicon carbide is manufactured.
Of course, the main component of the constituent material of the honeycomb structure is not limited to silicon carbide. Other examples include nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, zirconium carbide, and titanium carbide. And carbide ceramics such as tantalum carbide and tungsten carbide, and oxide ceramics such as alumina, zirconia, cordierite, mullite, and aluminum titanate.
Of these, non-oxide ceramics are preferred, and silicon carbide is particularly preferred. It is because it is excellent in heat resistance, mechanical strength, thermal conductivity and the like. In addition, silicon-containing ceramics in which metallic silicon is blended with the above-mentioned ceramics, ceramics bonded with silicon or a silicate compound, and the like can also be cited as constituent materials. Among these, silicon carbide is blended with metallic silicon ( Silicon-containing silicon carbide) is desirable.

First, an inorganic powder such as silicon carbide powder having a different average particle size and an organic binder are dry mixed to prepare a mixed powder, and a liquid plasticizer, a lubricant and water are mixed to prepare a mixed liquid, Subsequently, a wet mixture for producing a molded body is prepared by mixing the mixed powder and the mixed liquid using a wet mixer.

The particle size of the silicon carbide powder is not particularly limited, but it is preferable to have less shrinkage in the subsequent firing step, for example, 100 parts by weight of powder having an average particle size of 0.3 to 50 μm and 0.1 to 1.0 μm. A combination of 5 to 65 parts by weight of a powder having an average particle diameter of 5 to 65 parts by weight is preferred.
In order to adjust the pore diameter and the like of the honeycomb fired body, it is necessary to adjust the firing temperature, but the pore diameter can be adjusted by adjusting the particle size of the inorganic powder.

The organic binder is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and polyethylene glycol. Of these, methylcellulose is desirable.
The amount of the binder is usually preferably 1 to 10 parts by weight with respect to 100 parts by weight of the inorganic powder.

It does not specifically limit as said plasticizer, For example, glycerol etc. are mentioned.
The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
Specific examples of the lubricant include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the mixed raw material powder.

Moreover, when preparing the said wet mixture, you may use a dispersion medium liquid, As said dispersion medium liquid, alcohol, such as water, organic solvents, such as benzene, methanol, etc. are mentioned, for example.
Furthermore, a molding aid may be added to the wet mixture.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol and the like.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide-based ceramics, spherical acrylic particles, and graphite may be added to the wet mixture as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

Further, the wet mixture using the silicon carbide powder prepared here preferably has a temperature of 28 ° C. or lower. It is because an organic binder may gelatinize when temperature is too high.
Further, it is desirable that the organic content in the wet mixture is 10% by weight or less.

The wet mixture is conveyed after preparation and supplied to a molding machine.
In the method for manufacturing a honeycomb structured body of the present invention, here, a transport device that can reduce the moisture content change rate of the wet mixture before and after the transport is used for transporting the wet mixture.
Specifically, the transport apparatus of the present invention already described can be used.

Here, in the manufacture of the honeycomb structure, a desirable value of the moisture content in the wet mixture when water is used as the dispersion medium will be described. The desirable lower limit of the moisture content in the wet mixture is 10% by weight. There is a more desirable lower limit of 12% by weight. The desirable upper limit of the water content in the wet mixture is 20% by weight, and the more desirable upper limit is 15% by weight. If the water content is less than 10% by weight, cracks and cell breakage are likely to occur in the molded body. On the other hand, if the water content exceeds 20% by weight, the extruded molded body has a certain shape until it is dried. This is because it becomes difficult to hold.
Therefore, it is necessary to control the moisture content of the wet mixture within the above range.

Here, in the extrusion molding process using the extrusion molding machine described later, various conditions such as the extrusion pressure and the extrusion speed are adjusted in accordance with the theoretical value of the moisture content when the wet mixture supplied to the extrusion molding machine is mixed. It is a process that is optimized and set, and is performed under the setting conditions.
Therefore, even if the measured value of the moisture content of the wet mixture supplied to the extruder is within the above range (10 to 20% by weight), if the difference between the theoretical value and the measured value of the moisture content is large, Due to inadequate extrusion molding conditions, it may not be possible to obtain a molded product of a certain quality.If the molded product is cracked, cut out of cells, etc., or if the extruded molded product is dried, it will have a certain shape. It may not be possible to keep it.

In particular, in the extrusion molding step in the manufacturing process of the honeycomb structure of the present invention, the moisture content is 10 to 20% by weight, and the difference between the measured value of the moisture content and the theoretical value is ± 3%. It is desirable to use a wet mixture that is within. When a wet mixture having a moisture content within the above range is used and extrusion molding is performed under the optimum extrusion conditions for the moisture content, cracks, cell breakage, etc. may occur in the molded product. This is because such a problem that the molded body cannot maintain a certain shape is less likely to occur.

In the method for manufacturing a honeycomb structured body of the present invention, since the transport is performed using the transport device described above, the amount of water evaporated in the casing is small, and drying of the wet mixture can be prevented. Therefore, it can carry out so that the moisture content change rate before and behind conveyance may become 3% or less. Moreover, when the conveyance apparatus which has a partition member is used, the quantity which a water | moisture content evaporates from a wet mixture can be decreased more, and the moisture content change rate before and behind a conveyance process can be made still smaller. Therefore, the wet mixture can be transported while maintaining an appropriate water content, and the wet mixture can be stably supplied to the extruder.

Further, in the case where the above-described transport device having a storage unit is used, it is of course possible to transport the wet mixture to the next-stage extrusion molding machine while maintaining an appropriate moisture content. That is, in the steps after the next step, which will be described later, even if a trouble occurs and the production line is stopped, the wet mixture can be temporarily stored in the storage unit. It can be operated without stopping.
In addition, as for the conveying apparatus of this invention used here, it is desirable to be able to store the wet mixture 1.5-3 times (weight conversion) of the shaping | molding capacity of an extrusion molding machine in a storage part.

In the method for manufacturing a honeycomb structured body of the present invention, it is desirable to store the wet mixture in the storage unit for a certain time when the prepared wet mixture is conveyed. This is because the moldability of the wet mixture is improved in the subsequent extrusion process.
The reason for this is not clear, but it is considered that the wet mixture is refrigerated and aged, and during this refrigerated aging, the organic binder swells to improve the lubricity of the inorganic particles (silicon carbide particles). .
When the wet mixture is stored for a certain period of time, the storage time is not particularly limited, but a desirable lower limit is 1 hour, a more desirable lower limit is 4 hours, a desirable upper limit is 10 hours, and a more desirable upper limit is 8 hours.
When the storage time is less than 1 hour, the moldability of the wet mixture is hardly improved, and when the storage time is longer than 10 hours, the wet mixture is partially dried, and conversely, the moldability is lowered. Because there is.
In addition, when the moldability of the wet mixture is improved, the molding pressure during extrusion molding can be reduced, and by reducing the molding pressure, the incidence of molding defects can be reduced. The life of consumable parts (molds, etc.) constituting the machine can be extended.

During the storage, it is desirable to provide an openable / closable opening / closing plate in the storage unit of the transport device, and to close the storage unit by closing the opening / closing plate during storage. Since the space in which the stored wet mixture exists can be narrowly divided, the wet mixture stored in the storage unit can be prevented from drying, and the wet mixture having the optimum moisture content is supplied to the extrusion process. This is because it can be done.

Subsequently, an extrusion molding process is performed.
In the method for manufacturing a honeycomb structure of the present invention, the extruder used in the extrusion process is not particularly limited, but an example of the extruder and an extrusion method using the extruder will be described with reference to the drawings. .

FIG. 4 is a cross-sectional view schematically showing an example of an extrusion molding machine used in the extrusion molding process.
This extruder 220 is a two-stage screw mixer, an upper screw mixer 241 and a lower screw mixer 261, provided with a screw having a stirring rod (screw shaft) and a stirring blade (screw blade) inside. It has.

At one end of the upper screw mixer 241, there is provided a charging hopper 231 that receives a wet mixture of raw materials mixed in advance. A kneading push roller 242 for pushing into the inside is provided.

The kneading push roller 242 rotates inward so as to push the wet mixture dropped through the charging hopper 231 between the pair of kneading push rollers while kneading, and then pushes the wet mixture downward. It supplies the inside of the screw mixer 241.

The upper screw mixer 241 includes an upper screw 243 including a feed screw having a role of moving the wet mixture as well as kneading, and an entanglement screw mainly provided for kneading the wet mixture. In a feed screw, screw blades (stirring blades) are spirally wound around a screw shaft, and kneading is performed by the blades and a wet mixture is pushed forward.

In the entanglement screw, a plurality of screw blades are formed so as to form a ring in the circumferential direction of the screw shaft, and a part thereof is cut obliquely, and there is a portion without the screw blades. The kneading further proceeds as the wet mixture passes through this portion.

The other end of the upper screw mixer 241 is provided with an upper die (die) having a large number of through holes. The wet mixture passes through the twining screw and is then pushed into the upper die so that the wet mixture Extruded in a stick-like or udon noodle state.

A decompression chamber 246 is provided in a portion where the wet mixture is extruded from the upper die, and the inside thereof is in a decompressed state close to a vacuum. Note that the insides of the upper screw mixer 241 and the lower screw mixer 261 are also kept at a reduced pressure. This is to prevent bubbles (air) from getting caught in the wet mixture. If bubbles are bitten into the wet mixture, defects due to the bubbles are likely to occur in the partition walls and the like when the molded body is produced.

An upper cutter 245 as a cutting member is provided in the decompression chamber 246 and in the vicinity of the upper die. That is, the blade of the upper cutter 245 exists inside the decompression chamber 246, and the air cylinder provided in the decompression chamber 246 causes the blade portion to reciprocate up and down in the vicinity of the upper die so that it becomes a udon noodle-like shape from the upper die. The wet mixture extruded into a rod shape is cut into fine lumps.

A number of the cut small lumps fall into the receiving port 269 of the lower screw mixer 261 immediately below, and are pushed into the lower screw mixer 261 by the kneading push roller 262 configured in the same manner as the kneading push roller 242 described above. It is. Thereby, the degree of mixing further proceeds.

The lower screw mixer 261 includes a lower screw 263 including a feed screw and a W blade screw provided at the tip thereof, and is quantitatively pushed into the die 264 at the tip portion.
In this way, by repeating kneading, the mixing proceeds sufficiently, and a square mixture shape in which a large number of cells are formed in the longitudinal direction is continuously extruded from the die 264 as a uniform mixture with respect to moisture and composition. The formed body is continuously formed.

Further, in the extrusion molding machine 220 shown in FIG. 1, it is pushed into the screw mixer by the kneading pusher, but it may be pushed into the screw mixer by other means, and only the charging hopper is formed. But you can. Moreover, the combination of the screw provided in the inside of a screw mixer is not limited to the combination mentioned above, For example, it may be comprised only from the field screw and the other combination may be sufficient.

In this extruder 220, the time from when the wet mixture enters the extruder 220 until it is extruded is preferably 50 to 90 minutes. This is because it is necessary to make the entire composition uniform including water and the like by mixing well.
Moreover, as for the speed | rate at which a molded object is extruded in the case of extrusion molding, 3500-4500 mm / min is desirable. If it is less than 3500 mm / min, production efficiency is lowered, which is not desirable. On the other hand, if it exceeds 4500 mm / min, it becomes difficult to obtain a honeycomb molded body having the designed dimensions, and the manufactured honeycomb molded body has defects. It tends to occur.
These molding conditions need to be set to optimum values according to the theoretical value of the water content when the wet mixture is prepared.

By supplying the wet mixture conveyed by the conveying device to the extrusion molding machine, a columnar honeycomb molded body in which a large number of cells are arranged in parallel in the longitudinal direction across the cell wall can be formed by extrusion molding. it can.

Next, the honeycomb formed body is dried using a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like.
Then, if necessary, the end side of the inlet side cell group and the end side of the outlet side cell group at the inlet side are filled with a predetermined amount of sealing material paste as a sealing material, and the cells are To seal.

Although it does not specifically limit as said sealing material paste, The thing from which the porosity of the sealing material manufactured through a post process becomes 30 to 75% is desirable, For example, the thing similar to the said wet mixture can be used. .
Next, the honeycomb formed body filled with the sealing material paste and dried is degreased (for example, 200 to 500 ° C.) and fired (for example, 1400 to 2300 ° C.) under a predetermined condition. A honeycomb fired body in which the cells are juxtaposed in the longitudinal direction across the cell wall and any one end of the cells is sealed can be manufactured.
As the conditions for degreasing and firing the honeycomb formed body, the conditions conventionally used when manufacturing a filter made of a porous ceramic can be applied.

Next, a sealing material paste serving as a sealing material layer is applied to the side surface of the honeycomb fired body with a uniform thickness to form a sealing material paste layer, and another honeycomb fired body is sequentially formed on the sealing material paste layer. The process of laminating is repeated to produce an aggregate of honeycomb fired bodies having a predetermined size.

As said sealing material paste, what consists of an inorganic binder, an organic binder, an inorganic fiber, and / or an inorganic particle etc. are mentioned, for example.
Examples of the inorganic binder include silica sol and alumina sol. These may be used alone or in combination of two or more. Among the inorganic binders, silica sol is desirable.

Examples of the organic binder include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Among the organic binders, carboxymethyl cellulose is desirable.

Examples of the inorganic fiber include ceramic fibers such as silica-alumina, mullite, alumina, and silica. These may be used alone or in combination of two or more. Among the inorganic fibers, alumina fibers are desirable.

Examples of the inorganic particles include carbides and nitrides, and specific examples include inorganic powders made of silicon carbide, silicon nitride, and boron nitride. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide having excellent thermal conductivity is desirable.

Furthermore, a pore-forming agent such as a balloon, which is a fine hollow sphere containing an oxide-based ceramic, spherical acrylic particles, or graphite, may be added to the sealing material paste as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

Next, the aggregate of the honeycomb fired bodies is heated to dry and solidify the sealing material paste layer to form a sealing material layer (adhesive layer).
Next, using a diamond cutter or the like, an aggregate of honeycomb fired bodies in which a plurality of honeycomb fired bodies are bonded via a sealing material layer (adhesive layer) is cut to produce a cylindrical ceramic block.

Then, by forming a sealing material layer on the outer periphery of the ceramic block using the sealing material paste, a plurality of honeycomb fired bodies are bonded to each other through the sealing material layer (adhesive layer). A honeycomb structure having a sealing material layer (coat layer) provided on the outer periphery can be manufactured.

Thereafter, if necessary, a catalyst is supported on the honeycomb structure. The catalyst may be supported on the honeycomb fired body before producing the aggregate.
When the catalyst is supported, it is desirable to form an alumina film having a high specific surface area on the surface of the honeycomb structure, and to apply a promoter such as platinum and a catalyst such as platinum to the surface of the alumina film.

As a method for forming an alumina film on the surface of the honeycomb structure, for example, a method in which a honeycomb structure is impregnated with a solution of a metal compound containing aluminum such as Al (NO ₃ ) ₃ and heated, an alumina powder is contained. For example, the honeycomb structure may be impregnated with a solution to be heated and heated.
Examples of a method for applying a promoter to the alumina film include a method in which a honeycomb structure is impregnated with a solution of a metal compound containing a rare earth element such as Ce (NO ₃ ) ₃ and heated. .
As a method for imparting a catalyst to the alumina membrane, for example, a dinitrodiammine platinum nitric acid solution ([Pt (NH ₃ ) ₂ (NO ₂ ) ₂ ] HNO ₃ , platinum concentration 4.53% by weight) or the like is applied to the honeycomb structure. Examples of the method include impregnation and heating.
Alternatively, the catalyst may be applied by a method in which a catalyst is applied to the alumina particles in advance, and the honeycomb structure is impregnated with a solution containing the alumina powder to which the catalyst is applied and heated.

Further, the method for manufacturing a honeycomb structure described so far has a structure in which a plurality of honeycomb fired bodies are bundled through a sealing material layer (adhesive layer) (hereinafter also referred to as a collective honeycomb structure). However, the honeycomb structure manufactured by the manufacturing method of the present invention is a honeycomb structure in which a cylindrical ceramic block is composed of one honeycomb fired body (hereinafter also referred to as an integral honeycomb structure). May be.

When manufacturing such an integral honeycomb structure, first, the aggregated honeycomb structure is formed except that the size of the honeycomb molded body formed by extrusion molding is larger than that when manufacturing the aggregated honeycomb structure. A honeycomb formed body is manufactured by using the same method as that for manufacturing.
Here, since the method of conveying and storing the wet mixture before forming is the same as the method of manufacturing the aggregated honeycomb structure, the description thereof is omitted here.

Next, similarly to the production of the aggregated honeycomb structure, the honeycomb formed body is dried using a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer, or the like. A honeycomb dried body is obtained. Next, a predetermined amount of a sealing material paste serving as a sealing material is filled in the outlet side end portion of the inlet side cell group and the inlet side end portion of the outlet side cell group, and the cells are sealed.
Thereafter, in the same manner as in the production of the aggregated honeycomb structure, a ceramic block is produced by performing degreasing and firing, and if necessary, a sealing material layer (coat layer) is formed, whereby an integral honeycomb structure is obtained. Can be manufactured. Further, the above-mentioned integral honeycomb structure may be loaded with a catalyst by the method described above.

As described above, in the method for manufacturing a honeycomb structure of the present invention described above, a wet mixture having an appropriate water content can be stably supplied to an extrusion molding machine, and cracks and cells are cut in the extrusion molding after the extrusion process. A honeycomb structure can be manufactured without the occurrence of the above.
In addition, when a honeycomb structure is manufactured by the above-described method, a series of manufacturing steps may be performed on one manufacturing line. For example, a transport device having a distribution mechanism is used as a transport device, and a wet mixture is charged. The steps up to this may be performed on one production line, and the steps after the step of producing a molded body using an extruder may be performed on two or more production lines.
In this case, the wet mixture is distributed and supplied to each production line in a timely manner by the distribution mechanism provided in the transport device.

Hereinafter, in the method for manufacturing a honeycomb structure using the conveyance device of the present invention, the molding conditions of the extruder are optimum when the moisture content of the wet mixture supplied to the extruder is 13.4% by weight. A honeycomb molded body is manufactured by performing an extrusion molding process under the extrusion molding conditions, and measuring a change in the moisture content of the wet mixture before and after the transport process and a pressure value at the time of extrusion molding. Evaluate the appearance of the molded body (presence or absence of surface roughness, presence or absence of cracks, presence or absence of partial holes or cracks in cell walls or presence or absence of cells) and warpage, and moisture in the wet mixture before and after the transport process The correlation between the content, the moisture content change rate of the wet mixture before and after the conveying step, and the number of defective products was evaluated.
In addition, the moisture content change rate of the wet mixture before and after the conveyance process is the moisture content of the wet mixture when the wet mixture after kneading is charged into the conveyance device (moisture content before conveyance) and the extrusion mixture. It is the rate of change of the moisture content of the wet mixture obtained from the moisture content of the wet mixture immediately before being carried out (water content after conveyance), and is specifically obtained from the following formula (1).
Moisture content change rate of the wet mixture before and after the transport process = (water content after transport−water content before transport) / water content before transport (1)
If the wet mixture is temporarily stored in the storage unit or the like before being put into the extruder, the moisture content of the wet mixture immediately after being put into the extruder is included in the transport process (after transport) Calculated using the water content.

As the extrusion molding conditions optimized when the moisture content of the wet mixture is 13.4% by weight, the molding speed and molding pressure in each example were 4000 mm / min and 5.8 MPa, respectively. Set.
The transfer device was installed in a room at about 20 ° C.
In addition, FIG. 5 is sectional drawing which shows typically the site | part which measures the pressure value at the time of extrusion molding.

(Example 1)
250 kg of α-type silicon carbide powder having an average particle size of 10 μm, 100 kg of α-type silicon carbide powder having an average particle size of 0.5 μm, and 20 kg of an organic binder (methylcellulose) were mixed to prepare a mixed powder.
Next, separately, 12 kg of lubricant (Unilube, manufactured by NOF Corporation), 5 kg of plasticizer (glycerin), and 60 kg of water are mixed to prepare a liquid mixture, and this liquid mixture and the mixed powder are mixed in a wet mixer. A wet mixture was prepared by mixing and the moisture content was measured.

The moisture content in the wet mixture was measured using about 2 g of the wet mixture using a halogen moisture meter HR83 manufactured by METTLER TRADE.

Next, the conveyance process which conveys this wet mixture to the extruder 220 using the conveying apparatus 30 of this invention shown in FIG. 1 was performed.
As this conveying device, as shown in FIG. 1, a device provided with a casing 33 and four partition members 38 was used.
The transport device 30 shown in FIG. 1 includes a distribution mechanism. However, in this embodiment, the distribution mechanism is not used, and the wet mixture charged from the charging port 34 is stored via the belt conveyor 35. It was conveyed to part 31A.
The distance from the charging port 34 to the storage unit 31A is about 5 m in the horizontal direction, and the charging hopper 231 of the extruder 220 shown in FIG. 4 is connected to the lower part of the storage unit 31A.
Next, the wet mixture was stored in the storage unit 31A with the storage time of the wet mixture within 0.5 hours, and then supplied to the charging hopper 231 of the extrusion machine 220 connected directly below the storage unit 31A.

Here, a part of the wet mixture supplied to the charging hopper 231 was extracted, and the moisture content of the wet mixture after conveyance was measured.
The moisture content of the wet mixture after conveyance measured and the moisture content of the wet mixture before conveyance measured previously were compared, and the change rate of the moisture content before and after conveyance was calculated.

As described above, the extrusion molding machine 220 is extruded at a molding speed and a molding pressure of 4000 mm / min and 5.8 MPa, respectively, and the honeycomb fired body 140 (see FIGS. 7A and 7B) is used. A generation feature 144 (see FIG. 5) having the same shape was produced.
At this time, as shown in FIG. 5, a pressure sensor 270 was disposed 10 cm forward from the outlet of the die 264, and the pressure value at the time of extrusion molding was measured.
As a pressure sensor, a stainless steel small pressure transducer (PGM-500KD) manufactured by Kyowa Dengyo was used.

Next, after drying the produced | generated form 144 using a microwave dryer etc., the sealing material paste of the composition similar to the said wet mixture was filled into the predetermined | prescribed cell.
Next, after drying again using a dryer, degreasing is performed at 400 ° C., and firing is performed at 2200 ° C. for 3 hours under an atmospheric pressure of argon atmosphere, whereby the porosity is 40% and the average pore diameter is 12.5 μm. A honeycomb fired body comprising a silicon carbide sintered body having a size of 34.3 mm × 34.3 mm × 150 mm, a cell number (cell density) of 46.5 cells / cm 2, and a cell wall thickness of 0.25 mm. Manufactured.

Next, 30% by weight of alumina fibers having an average fiber length of 20 μm, 21% by weight of silicon carbide particles having an average particle diameter of 0.6 μm, 15% by weight of silica sol, 5.6% by weight of carboxymethyl cellulose, and 28.4% by weight of water were added. The thickness of the sealing material layer (adhesive layer) is obtained by adhering a large number of honeycomb fired bodies using the heat-resistant sealing material paste, and drying at 120 ° C., followed by cutting with a diamond cutter. A 1.0 mm cylindrical ceramic block was produced.

Next, silica-alumina fiber (average fiber length: 100 μm, average fiber diameter: 10 μm) is 23.3% by weight as inorganic fibers, 30.2% by weight of silicon carbide powder having an average particle diameter of 0.3 μm as inorganic particles, and silica sol as an inorganic binder (SiO ₂ content in sol: 30% by weight) 7% by weight, carboxymethyl cellulose 0.5% by weight and 39.0% by weight of water as an organic binder were mixed and kneaded to prepare a sealing material paste.

Next, a sealing material paste layer having a thickness of 0.2 mm was formed on the outer periphery of the ceramic block using the sealing material paste. Then, this sealing material paste layer was dried at 120 ° C. to prepare a cylindrical honeycomb structure having a diameter of 143.8 mm and a length of 150 mm, in which a sealing material layer (coat layer) was formed on the outer periphery.
The above manufacturing process was repeated to produce 10 honeycomb structures.

The produced honeycomb molded body is visually inspected mainly with respect to the shape of the cell, and the desired shape is obtained without causing a loose state, cracks, partial holes or cracks or cell breakage on the surface of the cell wall. In addition, the amount of warpage of the honeycomb formed body was measured. Then, a cell wall surface with no roughness, cracks, partial holes or cracks, no cell breakage, a good appearance shape, and a warp amount of less than 0.5 mm were evaluated as non-defective products. The results are shown in Table 1.

Note that the amount of warpage was measured using a warpage amount measuring jig.
As a jig for measuring the amount of warpage, in a straight square member having almost the same length as the entire length of the molded body, contact members having the same thickness are disposed at both ends of the square member, and the center of the square member is also provided. A scale slidable perpendicularly to the longitudinal direction of the square bar was used. Further, at the time of measurement, the contact member is brought into contact with the vicinity of both ends of the molded body, and then the warp amount measuring scale is moved to the molded body side, and the amount of movement of the scale when the molded body and the scale come into contact is read. The amount of warpage was measured.

(Examples 2 to 4)
The wet mixture was prepared in the same manner as in Example 1 except that the time for storing the wet mixture in the storage unit 31A was 1, 2, and 3 hours, respectively, and the moisture content was measured before and after conveyance, and the pressure during extrusion molding. Value measurement, production and evaluation of a honeycomb structure were performed. The results are shown in Table 1.

(Example 5)
A wet apparatus is prepared in the same manner as in Example 4 except that the transfer apparatus shown in FIG. 1 that does not include the partition member 38 is used, and the moisture content is measured before and after the transfer, and at the time of extrusion molding. Measurement of pressure value, production and evaluation of honeycomb structure were performed. The results are shown in Table 1.

(Comparative Examples 1-4)
During the transport process, the transport device is similar to the transport device used in Example 1, and transports using the transport device that does not include the casing 33 and the partition member 38, and stores the wet mixture in the storage unit 31A. A wet mixture was prepared using the same method as in Example 1 except that the time was changed, and the moisture content was measured before and after conveyance, the pressure value was measured during extrusion, and the honeycomb structure was produced and evaluated. The results are shown in Table 1.

(Reference Examples 1 and 2)
The amount of water at the time of preparing the wet mixture was set as shown in Table 1, and the moisture content of the wet mixture before transportation was 9.9% by weight and 20.1% by weight, respectively, as in Example 1. A wet mixture was prepared, the moisture content was measured before and after conveyance, the pressure value was measured during extrusion molding, and the honeycomb structure was produced and evaluated. The results are shown in Table 1.

From the experimental results shown in Table 1, in Examples 1 to 5 using the conveyance device 30 of the present invention, the moisture content change rate before and after conveyance is as extremely small as -0.2 to -3.0%, and before and after conveyance. It can be seen that drying of the wet mixture can be prevented.

Moreover, in Examples 1-5, the pressure value at the time of shaping | molding is close to 5.8 MPa which is a setting value of a shaping | molding machine.

Comparing these measurement results with the evaluation of the molded product, in Examples 1 to 5 in which the moisture content change rate is within -3.0%, the appearance shape is poor (the surface of the cell wall is in a rough state, cracks, partial No cracks or cracks or cell breakage), and no warping defects have occurred.
From this, it can be seen that when the moisture content change rate before and after conveyance is within 3.0%, favorable extrusion conditions can be obtained, and the occurrence of appearance defects and warping defects can be prevented.
That is, it is possible to prevent the occurrence of cracks, cell breakage, and the like due to drying of the wet mixture by performing the transport process of transporting the wet mixture using the transport device of the present invention.

In Comparative Examples 1 to 4, the moisture content change rate before and after conveyance is as large as −3.2 to −9.6%, and the pressure value during molding is also 6.8 to 7.2 MPa, which is a setting value of the molding machine. It is considerably higher than a certain 5.8 MPa.

Further, in Comparative Examples 1 and 2, appearance shape defects occurred, but the surface of the cell wall was in a rough state, cracks and partial cracks occurred, but no cell breakage occurred. It was.
On the other hand, in Comparative Examples 3 and 4, the appearance shape defect occurred, the surface of the cell wall was in a rough state, and in addition to cracks and partial cracks, cell breakage occurred.
From these facts, it is considered that the appearance shape defect occurs as follows.
First, when the moisture content change rate increases, that is, when the moisture content of the wet mixture decreases due to drying, the surface of the cell wall becomes loose. This is presumably because the bond between the ceramic particles and the organic binder powder becomes weak.
Furthermore, when the moisture content change rate is increased and the moisture content of the wet mixture is decreased, it is considered that the surface is roughly cracked, a hole is formed, or a crack is generated.
And when the moisture content change rate is further increased and the moisture content of the wet mixture is further decreased, it is considered that cell breakage occurs.

Further, the increase in the pressure value during molding is due to the difficulty of extruding the raw material by drying, and it is considered that an appearance shape defect has occurred due to such inappropriate molding conditions.
Therefore, it is clear that such a conveyance process is inappropriate as a conveyance process.

In addition, as shown in Reference Example 1, when the moisture content after transportation is 10% by weight or less, the rate of change in moisture content before and after transportation is small, but the moisture content of the wet mixture is small, so Since the pressure value is as high as 7.7 MPa and extrusion molding is performed under an inappropriate extrusion condition, it is considered that a defective appearance shape has occurred. From this, it can be seen that the moisture content of the wet mixture after conveyance is desirably 10% by weight or more.

Furthermore, as shown in Reference Example 2, when the moisture content after conveyance is 20% by weight or more, the moisture content change rate before and after conveyance is small, but the dried product is dried because the moisture content of the generated shape after conveyance is high. It is difficult to maintain a certain shape by the time, and a warp defect has occurred. From this, it is understood that the moisture content of the wet mixture after conveyance is desirably 20% by weight or less.

Also, if the pressure value at the time of molding becomes high, the die tends to wear out and the durability deteriorates, so it is desirable to perform molding at a pressure value close to the setting value of the molding machine from the viewpoint of the durability of the die. It is done.

It is sectional drawing which shows an example of the conveying apparatus of this invention typically. It is sectional drawing which shows typically another example of the conveying apparatus of this invention. (A) is a top view which shows typically another example of the conveyor which comprises the conveying apparatus of this invention, (b) is sectional drawing of (a). (A) is a top view which shows typically another example of the conveyor which comprises the conveying apparatus of this invention, (b) is sectional drawing of (a). It is sectional drawing which shows typically an example of the extrusion molding machine used for an extrusion molding process. It is sectional drawing which shows typically the site | part which measures the pressure value at the time of extrusion molding. It is a perspective view which shows typically an example of a honeycomb structure. (A) is a perspective view which shows typically the honeycomb fired body which comprises a honeycomb structure, (b) is the AA sectional view taken on the line.

Explanation of symbols

30, 50 Conveying devices 31A, 31B, 51 Storage unit 32, 52 Conveying unit 33, 53 Casing 35, 55A, 55B Belt conveyor 38, 58 Partition member 65, 75 Conveyor 130 Honeycomb structure 140 Honeycomb fired body 141 Cell 143 Cell wall 220 Extruder

Claims (9)

A transport unit provided with a conveyor for transporting the wet mixture;
A transfer apparatus characterized in that the moisture content change rate of the wet mixture before and after transfer is 3% or less. The conveying apparatus of Claim 1 provided with the storage part for storing the said wet mixture temporarily. The said conveying part is a conveying apparatus of Claim 1 or 2 comprised from the casing and the belt conveyor arrange | positioned in the said casing. The conveying apparatus according to claim 3, wherein a partition member for partitioning the inside of the casing is disposed in the vicinity of the downstream end portion of the belt conveyor. A columnar honeycomb formed body in which a large number of cells are juxtaposed in the longitudinal direction across a cell wall by extrusion molding after performing a transporting process for transporting a wet mixture containing a wet-mixed inorganic powder to an extrusion molding process. A method for manufacturing a honeycomb structure, comprising manufacturing and firing the honeycomb formed body to manufacture a honeycomb structure made of the honeycomb fired body,
In the transporting step, the wet mixture is extruded using a transporting device provided with a transporting unit in which a conveyor for transporting the wet mixture is provided, and the moisture content change rate of the wet mixture before and after transporting is 3% or less. A method for manufacturing a honeycomb structure, wherein the method is conveyed to a molding machine. The method for manufacturing a honeycomb structure according to claim 5, wherein the conveying device includes a storage unit for temporarily storing the wet mixture. The method for manufacturing a honeycomb structure according to claim 5 or 6, wherein the transport unit includes a casing and a belt conveyor disposed in the casing. The method for manufacturing a honeycomb structure according to claim 7, wherein a partition member for partitioning the inside of the casing is disposed in the vicinity of the downstream end of the belt conveyor. The method for manufacturing a honeycomb structured body according to any one of claims 5 to 8, wherein a moisture content after conveyance of the wet mixture is 10 to 20% by weight.

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