Die for extruding ceramic honeycomb structural bodies

Details Die for extruding ceramic honeycomb structural bodies Die for extruding ceramic honeycomb structural bodies

1999-08-24

2001-11-13

Nguyen, Nam (Department: 1722)

Plastic article or earthenware shaping or treating: apparatus

With apparatus assembly or dismantling means or with idle part

For extrusion or injection type shaping means

C425S38200R, C425S463000, C425S467000, C264S177120

Reexamination Certificate

active

06315545

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a die for extruding ceramic honeycomb structural bodies having a plurality of through holes defined by partition walls.
2. Description of Related Art
Generally, as a catalyst carrier and a particulate purifying filter, both used for purifying an exhaust gas from internal combustion engines, or, as a filter used for purifying/deoxidizing a combustion gas of oil or various gases, ceramic honeycomb structural bodies are used. Especially, as a ceramic honeycomb structural body used for the catalyst carrier for purifying an exhaust gas from the internal combustion engines, in order to achieve an improvement of exhaust gas purifying efficiency, a decrease of pressure loss, and a use under high temperatures, it is required to have more thinner partition walls and more larger number of through holes.
To meet the requirements mentioned above, when the ceramic honeycomb structural bodies having more thinner partition wall is to be formed by an extrusion forming method using a die, it is necessary to decrease sizes of slit widths of ceramic batch discharge slits and sizes of hole diameters of ceramic batch supply holes in response to a thinner wall to be required. In this case, there is a drawback such that a die manufacturing becomes extremely difficult and thus larger manufacturing steps are required. Moreover, there are drawbacks on working precision, cost, and time of delivery.
In order to eliminate the drawbacks mentioned above, the applicant proposed a die for extruding ceramic honeycomb structural bodies in U.S. Pat. No. 4,687,433 (Japanese Patent Publication No. 64-7843:JP-B-64-7843).
FIG. 5
is a schematic view showing one embodiment of the die for extruding ceramic honeycomb structural bodies disclosed in U.S. Pat. No. 4,687,433. In
FIG. 5
, a known die
51
for extruding ceramic honeycomb structural bodies comprises a plurality of ceramic batch discharge slits
54
and a plurality of ceramic batch supply holes
52
. In the die
51
, a plurality of pipes
53
are fitted into at least some of the ceramic batch supply holes
52
.
In the die
51
having the construction mentioned above, there is a merit such that an extrusion die for extruding ceramic honeycomb structural bodies having thin walls can be manufactured easily without using a special working means. However, in the die
51
having the construction mentioned above, as shown in
FIG. 5
, a tip portion
53
a
of the pipe
53
is inserted into the ceramic batch supply hole
52
to its bottom portion
52
a.
Therefore, there is the tip portion
53
a
of the pipe
53
all around a portion d of the ceramic batch discharge slit
54
in its tip portion
54
a
. As a result, a ceramic batch to be extruded, which is supplied via the ceramic supply hole
52
, is supplied into the ceramic batch discharge slit
54
only through a portion e in the tip portion
54
a
of the ceramic batch discharge slit
54
. In this case, if the ceramic batch discharge slit
54
is arranged by deeply cutting, there is a drawback that only a part of the deep ceramic batch discharge slit
54
is used for a ceramic batch discharge. Moreover, if only a part of the ceramic batch discharge slit
54
is used for a ceramic discharge, it is difficult to discharge uniformly a ceramic batch from the ceramic batch discharge slit
54
. In this case, a thickness of the wall after extruding is not uniform, the ceramic honeycomb structural body after extruding is deformed, and, in an extreme case, the ceramic honeycomb structural body can not be extruded.
SUMMARY OF THE INVENTION
An object of the invention is to eliminate the drawbacks mentioned above and to provide a die for extruding ceramic honeycomb structural bodies which can eliminate the drawbacks of pipes when ceramic batch supply holes are formed by using the pipes and which can extrude the ceramic honeycomb structural bodies having excellent properties.
According to the invention, a die for extruding ceramic honeycomb structural bodies, comprises a plurality of ceramic batch discharge slits, a plurality of ceramic batch supply holes communicated with said ceramic batch discharge slits, and a plurality of pipes fitted into at least some of said ceramic batch holes, wherein said pipes are inserted into said ceramic batch supply holes in such a manner that tip portions of said pipes are located apart from bottom portions of said ceramic batch supply holes.
In the present invention, the pipes are inserted in such a manner that the tip portions of the pipes are located apart from the bottom portions of the ceramic batch supply holes, and, preferably, the locations of the tip portions of the pipes correspond to tip portions of the ceramic batch discharge slits. Therefore, it is possible to achieve a construction such that the tip portions of the pipes are not existent around at least a part of or all of the tip portions of the ceramic batch discharge slits, and a smooth ceramic batch supply from the ceramic batch supply holes to the ceramic batch discharge slits can be achieved, so that drawbacks of the pipes can be eliminated.
Moreover, in the case that the pipes are accommodated in pipe accommodation portions arranged to the ceramic batch supply holes, or that the pipes are arranged to inner surfaces of the ceramic batch supply holes and flanges are arranged integrally to projected end portions of the pipes, or that the pipes are fixed to the ceramic batch supply holes by using at least one support member, it is possible to prevent the movements of the pipes toward the bottom portions or the open end portions of the ceramic batch supply holes, and thus theses cases are preferred embodiments. Further, it is preferred to arrange surface coating portions to the ceramic batch discharge slits and the ceramic batch supply holes under such a condition that the pipes are inserted into the ceramic batch supply holes, and also it is preferred to arrange the surface coating portions to the ceramic batch discharge slits and the ceramic batch supply holes before the pipes are inserted into the ceramic batch supply holes. When the surface coating portions are arranged, it is possible to form an R (round) portion to the ceramic batch discharge slits, and thus it is a preferred embodiment for extruding the ceramic honeycomb structural bodies.
In the present invention, a phrase “a plurality of pipes are fitted into at least some of the ceramic batch supply holes” means not only the case such that the pipes are inserted into some of a plurality of ceramic batch supply holes but also the case such that the pipes are inserted into all of a plurality of ceramic batch supply holes.


REFERENCES:
patent: 4445838 (1984-05-01), Groff
patent: 4687433 (1987-08-01), Ozaki et al.
patent: 4834640 (1989-05-01), Inoue et al.
patent: 5013232 (1991-05-01), Way
patent: 5487863 (1996-01-01), Cunningham et al.

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