JPH03232511A - Production of ceramic honeycomb filter - Google Patents

Abstract

PURPOSE:To repeatedly use a porous sheet by covering the second end face of a ceramic substrate with a shielding sheet and then introducing a powdery ceramic blocking material in the vicinity of the second end face in the air passage hole through the small holes of the perforated sheet to block the air passage hole. CONSTITUTION:The first end face 12 of a ceramic substrate 1 divided with a thin filter partition and having many air passage holes 2 communicating both end faces is covered with a perforated sheet 4, a powdery ceramic blocking material 7 is introduced into the hole 2 through the small holes 40 of the sheet 4, and the material is solidified to block the end of the hole 2. In this hole end blocking process, the second end face 11 of the substrate 1 is covered with a shielding sheet 8, and then the material 7 is introduced in the vicinity of the second end face in the hole 2 through the small hole 40 of the sheet 4 to block the hole 2 on the second end face 11 side. As a result, the sheet can repeatedly be used, and the end face of the substrate is smoothed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing a ceramic honeycomb filter, for example, a method of manufacturing a ceramic honeycomb filter that collects particulates discharged from an internal combustion engine. .

[Prior Art] Conventionally, a ceramic honeycomb filter for purifying exhaust gas from an internal combustion engine is manufactured by using a ceramic substrate having a large number of ventilation holes partitioned by filtration partition walls and communicating with both end faces. Close every other vent hole (in a checkerboard pattern) near the other end surface, and close every other vent hole that is not yet blocked near the other end surface (in a checkerboard pattern).
(Japanese Patent Application Laid-open No. 57-7)
215.59-54683).

In the manufacturing method of each of the above-mentioned publications, the hole end closing step of closing the ventilation holes in a checkerboard pattern involves covering one end surface of the ceramic substrate with a film in which a large number of small holes are regularly provided, and each small hole in the film is A slurry-like or clay-like ceramic plugging material is press-fitted into the vent through the vent hole to close the end of the vent on the one end surface side, that is, the side adjacent to the film.

Note that, as described above, since both end faces of the ceramic substrate are closed, two films are used for each ceramic substrate.

Note that the ceramic closing material is dried or heated to solidify after being press-fitted.

[Problems to be Solved by the Invention] However, in the hole end closing step described above, the film used absorbs water from the slurry-like or clay-like ceramic plugging material and swells, or wrinkles or deforms when it is applied and peeled off. This makes repeated use difficult, and as a result, a large amount of film is required for mass production of filters. Since a large number of small holes must be precisely formed in the film, the cost is not negligible.

Furthermore, since there are manufacturing variations in the positions of the ventilation holes in each ceramic substrate, alignment with the positions of the small holes provided in advance in the film may not be possible, resulting in poor closing.

Furthermore, since the clay-like or slurry-like (that is, viscous) ceramic plugging material is press-fitted into the vent hole, after assimilation, the ceramic plugging material protrudes from the press-fit side end surface of the ceramic base by the thickness of the film, and as a result, As a result, a large number of small protrusions are formed on both end surfaces of the ceramic substrate. If a large number of small protrusions are formed on both end faces of the ceramic base, these small protrusions may become an obstacle when installing the ceramic base in the housing case. When attached to the end face of the heater, these small protrusions have the disadvantage that thermal conductivity from the heater to the ceramic base is reduced.

An object of the present invention is to solve the above problems and provide a method for manufacturing a ceramic honeycomb filter that has flat end faces and is easy to manufacture.

[Means for Solving the Problems] A method for manufacturing a ceramic honeycomb filter of the first invention includes:
A porous sheet is attached to the first end surface of a ceramic substrate having a large number of ventilation holes separated by thin filtration partition walls and communicating with both end surfaces, and a ceramic plugging material is introduced into the ventilation holes through each small hole of the porous sheet. A method for manufacturing a ceramic honeycomb filter includes a pore end closing step of introducing a ceramic occlusion material and solidifying the introduced ceramic occlusion material to close an end of the vent hole, the pore end closing step comprising: After a shielding sheet is attached to the second end surface of the ceramic substrate, a powdered ceramic plugging material is introduced into the ventilation hole near the second end surface through the small hole of the porous sheet, and It is characterized in that the pores are closed on the second end surface side.

The method for manufacturing a ceramic honeycomb filter of the second invention includes:
A porous sheet is adhered to the first end surface of a ceramic substrate having a large number of ventilation holes separated by thin filtration partition walls and communicating with both end surfaces, and a ceramic clogging material is introduced into the ventilation holes through each small hole of the porous sheet. A method for manufacturing a ceramic honeycomb filter includes a pore end closing step of introducing a ceramic occlusion material and solidifying the introduced ceramic occlusion material to close an end of the vent hole, the pore end closing step comprising: It is characterized in that it is made by covering the porous sheet made of an elastic sheet.

[Effect of the invention] The method for manufacturing a ceramic honeycomb filter of the first invention includes:
After applying the shielding sheet to the second end surface of the ceramic base,
A powdered ceramic closing material is fed into the vent hole near the second end surface through each small hole of the porous sheet to close the vent hole on the second end surface side.

Therefore, the manufacturing method of the present invention provides the following advantages.

First of all, since the powdered ceramic plugging material is fed, there is no deformation due to water absorption and swelling of the porous sheet, and the position of each small hole in the porous sheet and the ventilation hole in the ceramic base is misaligned, resulting in poor feeding. The porous sheet can be used repeatedly.

Second, the solidified ceramic plugging material does not protrude from the press-fit side end face of the ceramic base as in the conventional case, and as a result, many small protrusions are not formed on both end faces of the ceramic base. Since the surface can be formed smooth, these small protrusions do not become an obstacle when installing the particulate combustion heater on the end face of the ceramic base. There is no disadvantage of reduced thermal conductivity to the substrate.

Thirdly, since there is no need to consider the formation of small protrusions mentioned above, the thickness of the porous sheet can be ensured sufficiently, which improves the shape stability of the porous sheet and prevents wrinkles when it is pasted and peeled off. Twisting and deformation can be prevented, and as a result, the porous sheet can be used repeatedly.

Fourthly, after one end face is closed by applying a porous sheet, it is no longer necessary to apply the perforated sheet to close the remaining end face, so the number of times the perforated sheet is used is reduced, and the process is simplified. Can be shortened.

As a result of the above, it becomes possible to manufacture a ceramic honeycomb filter that is most easily manufactured with flat end faces.

The method for manufacturing a ceramic honeycomb filter of the second invention includes:
An elastic sheet is used as the porous sheet.

Therefore, the manufacturing method of the present invention provides the following advantages.

First of all, even if the position of the ventilation holes in the ceramic substrate is out of alignment with respect to the small holes in the porous sheet due to manufacturing variations, the porous sheet has elasticity, so for example, a hole position correction needle can be passed through the small holes in the porous sheet. By inserting and holding the ceramic plug into the vent hole of the ceramic base, there will be no failure to feed the ceramic plug.

Second, even if the porous sheet is deformed when it is pasted and peeled off, it will restore its shape after use due to its elasticity, so the porous sheet can be used repeatedly.

As a result of the above, it becomes possible to manufacture a ceramic honeycomb filter that can prevent clogging defects and is easy to manufacture despite variations in the positions of the vent holes in each ceramic substrate.

[Example] (First Example) A method for manufacturing a honeycomb filter according to an example of the first and second inventions will be described with reference to FIGS. 2 to 4.

First, as shown in FIGS. 2 and 3, a cylindrical ceramic substrate 1, a porous sheet 4, and a shielding sheet 8 are prepared.

Ceramic base 1 is made of cordierite and has a diameter of 140 mm.
, the axial length is 180 mm. A large number of inflow passages 2 and discharge passages 3 (vent holes in the present invention) penetrate through the ceramic base 1 in the longitudinal direction at a constant pitch, and each passage 2.3 has a cross-sectional shape with one side being ''. It is a 1.4 mm square. The inflow passage 2 and the discharge passage 3 have a thickness of 0.4 mm.
It is divided by a filtration partition wall 10.

The porous sheet 4 is made of a silicone rubber sheet with a thickness of 1 mm, and is provided with a large number of small holes 40 in a checkered pattern. Each small hole 40 has a diameter of about 0.8 mm and is drilled using a laser. The pitch of each small hole 40 is twice the pitch of the inflow passage 2.

The shielding sheet 8 is made of a flat stainless metal plate.

Next, the ceramic substrate 1 is placed on the shielding sheet 8 so that one end surface 11 of the ceramic substrate 1 is in contact with the surface of the shielding sheet 8.

Next, the porous sheet 4 is placed on top of the ceramic substrate 1 with the other end surface 12 facing upward, the small holes 40 of the porous sheet 4 and the inflow passage 2 are aligned, and the porous sheet 4 is placed on the outer periphery of the ceramic substrate 1. Fix it nearby with pin 5.

Next, as shown in FIG. 3, a mixed powder of resin and ceramics (ceramic plugging material in the present invention) 7 is dropped into the inflow passage 2 through the small holes 40 of the porous sheet 4. The mixed powder 7 introduced is deposited on the shielding sheet 8 at the lower end of the inflow passage 2.

Next, as shown in FIG. 4, the shielding sheet 8 is heated by the heater 9.
The mixed powder 7 is heated through. As a result, the thermosetting resin in the mixed powder is cured, and the ceramic powder in the mixed powder 7 is encapsulated and fixed in the resin, and the resin is tightly adhered to the filtration partition wall 10.

Next, as shown in FIG. 4, the ceramic substrate 1 is turned upside down, one end surface 11 is placed on top, the other end surface 12 is placed on the sheet 8, and the mixed powder 7 is introduced into the discharge passage 3. At this time, all of the inflow passages 2 are already closed on the one end surface 11 side of the ceramic base 1, which is the upper end surface. Therefore, the porous sheet 4 is not required when the mixed powder 7 is introduced into the discharge passage 3, and the mixed powder 7 is directly introduced without the porous sheet 4.

Next, the mixed powder 7 deposited on the shielding sheet 8 at the lower end of the discharge passage 3 is heated to harden the thermosetting resin in the mixed powder 7, and the ceramic powder is encapsulated and fixed in the resin.

Next, the ceramic substrate 1 is heated to a temperature higher than the sintering temperature of the ceramic powder. As a result, the resin disappears, the ceramic powder and the ceramic base 1 are sintered, and
Both are integrated.

As a result, a ceramic honeycomb fill having the structure shown in FIG. 1 is obtained.

Mixed powder 7 contains 10 parts by weight of epoxy resin, 8 parts by weight of high-density polyethylene, and 3 parts by weight of a foaming agent as resin powder, and 31 parts by weight of talc, 16 parts by weight of silica, and 11 parts by weight of alumina as ceramic powder. and 21 parts by weight of aluminum hydroxide.

Heating temperature is approximately 150℃ for 10 minutes, sintering temperature is approximately 140℃
The temperature was set at 0°C for 300 minutes.

In addition, the small holes 40 of the porous sheet 4 and each passage 2.3 described above
If the pitch between the two is misaligned, use the elasticity of the porous sheet 40 to align the pin with the small hole 40.
and can be forcefully corrected by pushing into each passage 2.3.

As explained above, in this embodiment, the use of the porous sheet 4 and the above-mentioned positioning are not necessary when the discharge passage 3 is blocked, so that the mixed powder 7 can be easily and accurately charged.

In the above embodiments, other elastic sheets such as rubber-based sheets can be used as the porous sheet 4.

In addition, if only the first invention is implemented, the porous sheet 4
A porous metal plate or the like may be used instead.

The mixed powder 7 may be introduced into each passage 2.3 using an air flow or the like instead of falling due to gravity.

Furthermore, the ceramic substrate 1 may be photographed during feeding.

(Second Embodiment) In this embodiment, each passage 2 is different from the first embodiment described above.
．． This is a modification of the method of solidifying the mixed powder 7 introduced in 3.

That is, in this embodiment, a soluble resin binder that solidifies by reacting with water is used as the resin powder in the mixed powder 7, and a permeable sheet through which water can penetrate is used as the shielding sheet 8.

Then, the mixed powder 7 is deposited on the permeable sheet at the end of each passage 2.3, and then the soluble resin binder is humidified from below through the permeable sheet to harden the soluble resin binder and the plugging material composition ceramic powder is fixed.

As the soluble resin binder, methyl cellulose, ethyl cellulose, etc. can be used, and as the water-permeable shielding sheet 8, for example, a metal mesh in which a large number of micropores are formed can be used.

The soluble resin binder may be one that is soluble in a solvent other than water.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a ceramic honeycomb filter manufactured by the method of manufacturing a ceramic honeycomb filter of the first and second inventions, FIG. 2 is a cross-sectional view thereof, and FIG. FIG. 4 is a vertical cross-sectional view showing a state in which the ceramic plugging material is fed to one end surface side, and FIG. It is.

Claims (2)

[Claims] (1) A porous sheet is attached to the first end surface of a ceramic substrate having a large number of ventilation holes that are partitioned by thin filtration partition walls and communicate with both end surfaces, and the holes are inserted into the ventilation holes through each small hole of the porous sheet. A method for manufacturing a ceramic honeycomb filter, comprising a pore end closing step of introducing a ceramic occluding material and solidifying the introduced ceramic occluding material to close the end of the vent, the method comprising: In the step, after a shielding sheet is attached to the second end surface of the ceramic substrate, a powdered ceramic plugging material is introduced into the vent hole near the second end surface through the small pores of the porous sheet. . A method for manufacturing a ceramic honeycomb filter, characterized in that the ventilation holes are closed on the second end surface side. (2) A porous sheet is attached to the first end surface of a ceramic substrate having a large number of ventilation holes that are partitioned by thin filtration partition walls and communicate with both end surfaces, and the holes are inserted into the ventilation holes through each small hole of the porous sheet. A method for manufacturing a ceramic honeycomb filter, comprising a pore end closing step of introducing a ceramic occluding material and solidifying the introduced ceramic occluding material to close the end of the vent, the method comprising: A method for manufacturing a ceramic honeycomb filter, characterized in that the step is performed by applying the porous sheet made of an elastic sheet.