Honeycomb structural body-extruding die apparatus

A honeycomb structural body-extruding die apparatus is disclosed herein, which includes an extruding die and a die mask provided around an outer peripheral portion of the extruding die on an extruding material outlet side. The extruding die also includes a plurality of extruding material-feeding holes formed on the extruding material inlet side and a plurality of shaping channels formed communicating with each other in a lattice fashion on the extruding material outlet side. The honeycomb structural body-extruding die apparatus is further provided with an annular perforated plate arranged concentrically with the extruding die on the extruding material inlet side. The perforated plate has through holes of which respective central axes are in conformity with those of the extruding material feeding holes.

BACKGROUND OF THE INVENTION 
(b 1) Field of the Invention: 
The present invention relates to a honeycomb structural body-extruding die 
apparatus which can produce honeycomb structures of a good quality. 
(2) Related Art Statement: 
Heretofore, honeycomb structures have been produced by a honeycomb 
structural body-extruding die apparatus shown in FIG. 3, which comprises 
an extruding die 13 with holes 11 for feeding a material to be 
extrusion-shaped (hereinafter referred to as "extruding material-feeding 
holes"), which holes are formed on an extruding material inlet side, as 
well as shaping channels 12 communicated to one another in a lattice 
fashion on an extruding material outlet side, and a die mask 14 provided 
around the outer periphery of an end face of the extruding die 13 on the 
extruding material outlet side. 
In the above-mentioned conventional apparatus, since an outer peripheral 
wall is formed by squeezing the extruding material having passed through 
the outer peripheral portion of the extruding die at a tapered inner 
peripheral wall of the die mask 14, a speed of discharging the extruding 
material through the shaping channels of the die is greater at the outer 
peripheral portion than at the central portion. Therefore, there is a 
drawback in that cell deformation is likely to appear in an obtained 
honeycomb structural body near the outer peripheral wall thereof as seen 
at a portion "A" in FIG. 4. In order to eliminate such a drawback, 
Japanese patent publication No. 58-23,207 (U.S. Pat. No. 4,368,025) 
discloses a honeycomb structural body-extruding die apparatus in which a 
plurality of grooves are opened at a small interval along an inner 
peripheral edge portion of a die mask in contact with an end face of a die 
for feeding an extruding material forcedly fed into shaping channels at 
the peripheral portion of the die to the inside of the die mask. 
However, since no attention is paid to a difference in a discharging speed 
of the fed extruding material between the central portion and the outer 
peripheral portion in the above die apparatus, either, deformation of 
cells cannot be completely removed. Further, in the case that a plurality 
of the openings are provided along the inner periphery of the die mask, 
the dimension of such openings of the die mask needs to be slightly varied 
depending upon a shrinkage factor of the extruding material. In addition, 
to determine where a plurality of such openings are to be provided in what 
direction for the extrusion of honeycomb structures is extremely 
troublesome. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to eliminate the above mentioned 
drawbacks, and to provide a honeycomb structural body-extruding die 
apparatus which can easily produce good quality honeycomb structures free 
from troubles such as cell deformation. 
The honeycomb structural body-extruding die apparatus according to the 
present invention comprises an extruding die which has extruding 
material-feeding holes formed on an extruding material inlet side and 
shaping channels communicating with one another in a lattice fashion on an 
extruding material outlet side, and a die mask provided along an outer 
periphery of an end face of the extruding die on the extruding material 
outlet side, wherein an annular perforated plate is provided 
concentrically with the extruding die on the extruding material inlet 
side, and the perforated plate has holes of which central axes are in 
conformity with the corresponding extruding material-feeding holes, 
respectively. 
In the above construction, the speed of the extruding material discharged 
through the central portion and the peripheral portion of the extruding 
die is made at a desired constant value by the perforated plate arranged 
on the extruding material inlet side of the extruding die. Consequently, 
honeycomb structures of good quality can be obtained free from defects 
such as cell deformation. 
These and other objects, features and advantages of the invention will be 
appreciated upon reading of the following description of the invention 
when taken in conjunction with the attached drawings, with the 
understanding that some modifications, variations, and changes could be 
made by the skilled person in the art to which the invention pertains 
without departing from the spirit of the invention or the scope of the 
claims appended hereto.

DETAILED DESCRIPTION OF THE INVENTION 
A feeding speed of an extruding material varies depending upon a size of a 
honeycomb structural body-extruding apparatus, a composition of the 
extruding material, etc. However, optimum extruding conditions may be 
selected to effect an extruding operation by preliminarily preparing 
plural kinds of annular perforated plates for an extruding die and 
selectively attaching an appropriate perforated plate to the die. At that 
time, the feeding speed of the extruding material is finely adjusted by 
the perforated plate, preferably, according to a technique by which a 
diameter of holes of the perforated plate is varied, the inner diameter of 
the annular perforated plate is changed, or the thickness of the 
perforated plate is changed. 
The present invention will be explained in more detail with reference to 
the following specific embodiments. However, these embodiments are merely 
given in illustration of the invention, but they should never be 
interpreted to limit the scope of the invention. 
FIG. 1 is a sectional view of a principal portion of an embodiment of the 
honeycomb structural body-extruding die apparatus according to the present 
invention. In the illustrated embodiment, the extruding die 1 is 
constituted by extruding material-feeding holes 2 formed on an extruding 
material inlet side and shaping channels 3 which communicate with one 
another in a lattice fashion on an extruding material outlet side. An 
annular perforated plate 5 is concentrically arranged inside a cylinder 4 
on the extruding material inlet side of the extruding die 1. The 
perforated plate 5 is fixed to the extruding die 1 by means of screws or a 
jig (not shown) such that respective center axes of through holes 6 of the 
perforated plate 5 may be in conformity with those of the extruding 
material-feeding holes 2 of the extruding die 1. The honeycomb structural 
body-extruding die apparatus according to the present invention is 
constituted by the extruding die 1, the perforated plate 5, the cylinder 4 
and the die mask 7. 
FIGS. 2(a) through 2(c) are sectional views illustrating other embodiments 
of perforated plates 5 used in the present invention. In the embodiment of 
FIG. 2(a), the diameter of through holes 6 of the perforated plate 5 is 
made smaller toward the outer peripheral portion thereof so that the 
feeding speed of the extruding material is made greater at the inner 
peripheral portion of the perforated plate and smaller at the outer 
peripheral portion. In the embodiment illustrated in FIG. 2(b), the 
thickness of the perforated plate 5 is made larger toward the outer 
peripheral portion so that the feeding speed of the extruding material is 
made greater at the inner peripheral portion of the perforated plate and 
smaller at the outer peripheral portion. In the embodiment shown in FIG. 
2(c), the perforated plate 5 is constituted by two perforated annular 
plate members 5-1 and 5-2 and the inner diameter of the annular perforated 
plate member 5-1 in contact with the extruding die is made smaller than 
that of the perforated plate member 5-2 so that the feeding speed of the 
extruding material is made greater at the inner peripheral portion of the 
perforated plate 5 and smaller at the outer peripheral portion. 
In the above-illustrated honeycomb structural body-extruding die apparatus 
of the present invention, the speed of the extruding material, such as a 
ceramic body, which is discharged through the shaping channels of the die, 
may be controlled to be constant at every location by passing the 
extruding material through the perforated plate, when the extruding 
material passes through the extruding die. That is, when optimum 
perforated plates 5 are preliminarily determined correspondingly to 
changes in conditions such as a composition and a viscosity of an 
extruding material used, an inner diameter of a cylinder 4, etc. and the 
perforated plate 5 is exchanged depending upon the extruding material, 
etc., the discharging speed of the extruding material through the 
extruding die 1 on the extruding material outlet side can always be made 
constant. Consequently, when the outer periphery of the ceramic structure 
is formed by using the die mask 7, defects such as the cell deformation do 
not occur and the thickness of the cells can be made smaller. 
The present invention will not be limited to the above-mentioned 
embodiments only, and various modifications, variations, and changes of 
the same could be made. For example, in the above-mentioned embodiments, 
the outer walls of the honeycomb structures are formed by the die mask 
having a tapered portion. The outer walls may be formed by other 
appropriate conventional techniques. Although the perforated plates are 
exchangeably formed separatedly from the extruding die in the above 
embodiments, similar effects aimed at by the present invention may be 
obtained even when perforated plate may be integrally formed with the dies 
if exchange is unnecessary. 
As obvious from the foregoing detailed description, according to the 
honeycomb structural body-extruding die apparatus of the present 
invention, even when the extruding material passing through the outer 
periphery of the extruding die is squeezed to form the outer peripheral 
wall, the feeding speed of the extruding material on the extruding 
material outlet side of the extruding die can be made constant by 
providing the perforated plate concentrically with the extruding die on 
the extruding material inlet side. Therefore, the good quality honeycomb 
structures can be obtained free from defects such as cell deformation. 
Further, since the speed at which an extruding material passes through the 
die may be easily varied by changing the shape or the like of the 
perforated plate, the extruding apparatus most suitable for the extruding 
material used can be obtained only by a simple operation of exchanging the 
perforated plate.