JPH02102004A - Ceramic extrusion molding mold - Google Patents

Abstract

PURPOSE:To eliminate a sharp enlarged part and to prevent a fine crack from being caused in a wall part by curving a communicating groove which is communicated with a molding groove large in thickness of a partition wall among the passages wherein body is passed therethrough into a U-shape. CONSTITUTION:Ceramic body in a cylinder 4 is firstly pressed and fed to the feed hole 3 of a molding die 1 by a molding machine. Therein in the ceramic body feed holes 3a, 3e communicated with the molding grooves 2a, 2e large in the thickness of a partition wall vie the communicating holes 11a, 11e, the communicating passages are curved in the front and rear parts of the communicating holes 11a, 11e. Therefore ceramic body is fluidized at two times in the lateral direction and herein incorporated by large press-contacting force and an extremely sound ceramic honeycomb molded form is obtained. Thereafter a product free from the formation of a crack, etc., can be obtained by calcining this honeycomb molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an extrusion mold, and more specifically, it relates to an extrusion mold for extrusion molding, and more specifically for extrusion molding for a plurality of extrusion molds, such as a catalyst carrier for purifying exhaust gas of an internal combustion engine, a heat exchanger, or a rotor for a supercharger. The present invention relates to an extrusion mold for a ceramic honeycomb structure having partition wall thickness.

Hereinafter, a ceramic honeycomb structure refers to a structure having a plurality of through holes separated by partition walls.

(Prior Art) Conventionally, ceramic honeycomb structures having at least two types of film thicknesses have been used as catalyst carriers for automobile exhaust gas purification in order to improve the mechanical strength of the outer peripheral edge of the honeycomb structure. The outermost peripheral wall of the structure is made thicker (see Japanese Patent Publication No. 54-28850), or the thickness of the partition walls at the outer periphery of the honeycomb structure is made larger than the inside (see Japanese Patent Publication No. 57-50170). Are known. As an extrusion mold for such a structure, a holding plate is provided on the outer periphery of the forming groove corresponding to the cross-sectional shape of the ceramic honeycomb structure, and an extruded partition wall corresponding to the outer periphery of the forming groove is used. There have also been proposals for molds that have a structure in which the molding grooves are combined, and molds that have ceramic clay supply holes that are formed wide enough to correspond to the width of the molding grooves.

However, in molds with these structures, the through-holes are triangular in shape,
It can be applied to the extrusion of honeycomb structures that are geometrically relatively simple, such as rectangular shapes, and have relatively little change in barrier thickness. It has been impossible to extrude complex ceramic honeycomb structures because the extrusion speed of the clay becomes non-uniform.

In order to solve this problem, the present applicant first created forming grooves 2 (2a, 2b) corresponding to the cross-sectional shape of the ceramic honeycomb structure, as shown in FIGS. 6 and 7.

2c, 2d, 2e) and the ceramic clay supply hole 3 (3
a.

3b, 3c, 3d, 3e), and communicates with the forming grooves 2b, 2c, 2d having a small barrier thickness.

3c, 3d hydraulic diameter forming groove 2a with large barrier thickness;
The ceramic clay supply holes 3a and 2e communicate with each other, and are formed larger than the hydraulic diameter of the ceramic clay supply holes 3a and 3e.
We proposed an extrusion mold for Nicum structure (Japanese Patent Application Laid-Open No. 1989-1999)
(Refer to Publication No.-67111).

(Problem to be Solved by the Invention) Since the extrusion mold for this ceramic honeycomb structure has the above configuration, if this mold is used, both the thick and thin parts of the partition walls can be molded at the same extrusion speed. Therefore, a healthy ceramic honeycomb structure can be obtained.

However, in this extrusion mold, when the ceramic clay is extruded, the ceramic clay supply hole 3
Forming groove 2a has a larger barrier thickness than those in a and 3e.

At the transition point reaching 2e, the bulkheads are formed while rapidly expanding, so in the process of the clay coming out of the ceramic clay supply hole forming the partitions, the pressure force between the clay becomes weaker. As a result, the outer peripheral wall and the inner peripheral wall are filled with ceramic particles coarsely and unevenly, so that there are many coarse and fine labda inside the walls, and the strength after firing is low.

An object of the present invention is to solve the above-mentioned problems and to provide an extrusion molding die that can produce a ceramic honeycomb structure with good properties without the generation of minute particles or labda on the wall.

(Means for Solving the Problems) The extrusion molding mold of the present invention is an extrusion molding mold for a ceramic honeycomb structure having a plurality of barrier thicknesses and at least two or more through holes. Equipped with a molding groove corresponding to the molding groove and a ceramic clay supply hole communicating with the intersection or ridge of the molding groove,
The hydraulic diameter of the ceramic clay supply hole communicating with the forming groove with a small barrier thickness is formed to be larger than the hydraulic diameter of the ceramic clay supply hole communicating with the forming groove with a large barrier thickness, and the barrier thickness is large. It is characterized in that the communication groove of the ceramic clay supply hole communicating with the forming groove is bent in a U-shape.

(Function) In the above-mentioned configuration, by bending the communication groove that communicates with the forming groove with a large barrier thickness in a U-shape among the passages through which the clay passes, a sudden expansion part is eliminated and the clay is supplied from the supply hole. At the same time, a shearing force is applied to the ceramic clay, the clay is narrowed in the radial direction, and the passages of the clay are suddenly enlarged.
That is, since it is extruded in the lateral direction with a small change in the passage cross-sectional area, the pressing force between the ceramic clay becomes strong, and the obtained ceramic honeycomb structure is free from defects and its strength is improved.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

As shown in FIGS. 1, 2, 3, 4, and 5, an extrusion mold (hereinafter referred to as a mold) 1 for a ceramic honeycomb structure according to the present invention is mainly used for extrusion Ceramic clay supply holes (hereinafter referred to as supply holes) 3.3a, 3b arranged on the molding machine side.

3c, 3d, 3e and forming grooves 2.2a, 2b, 2c, 2 connected to the supply holes and forming the ceramic clay supplied to the supply holes into a desired ceramic honeycomb structure.
It consists of d and 2e. That is, since the forming grooves form the partition walls, inner circumferential wall, and outer circumferential wall of the ceramic honeycomb structure, depending on the type of thickness of the partition wall, for example, the forming groove has a large forming width when the partition wall thickness is large. 2a, 2e
Forming grooves 2b, 2c, and 2d are provided with a small forming width for those with small partition walls.

In the above configuration, in the present invention, the ceramic clay supply hole 3a, which communicates with the forming grooves 2a, 2e with large partition wall thickness,
3e and forming grooves 2a, 2e are bent at right angles inside to form ceramic clay supply holes 3a, 3e and forming grooves 2.
It is characterized in that it is connected by communication paths tta and tte that are parallel to a and 2e.

By bending the front and back of the communication passages 11a and lie, a shearing force is applied to the ceramic clay supplied from the supply hole and at the same time the clay is extruded in the lateral direction, so the pressure force between the ceramic clay becomes stronger. Unlike the prior art described above, defects do not occur in the obtained ceramic honeycomb structure.

The outer peripheral wall and the inner peripheral wall are connected to the outer peripheral wall by the inner peripheral surface of the frame 5, as shown in FIG. On the other hand, the outer circumferential surface of the ring piece 5' constituting a part of the mold 1 may form a part of the inner circumferential wall. As shown in the AA' cross section of FIG. 1, the outer circumferential wall may be partially formed by the ring 8, and the inner circumferential wall may be partially formed by the disk 8'.

As shown in FIG. 4 which is another embodiment, the cylinder 4 side of the forming groove of the supply hole 3 having approximately equal hydraulic diameters,
That is, in the ceramic clay inflow part of the supply hole 3, the forming groove 2a has a large forming width, and the opening 6a has a small hydraulic diameter in the forming groove 2e.
, 6e, moldings 12b, 2c, 2 with a small molding width
dl: Hydraulic diameter, AJ opening N6b, 6c.

6d may be provided on the supply hole side of the molding die 1, respectively. With the metal plate, the extrusion speed can be freely changed by changing the hole diameter of the metal plate without modifying the clay supply hole of the molding die.

The molding grooves can have various shapes and arrangements as shown in Figures 3, 4, and 5 depending on the shape of the ceramic honeycomb structure. It is formed by a known method such as processing.

The groove width of the forming groove is such that the ratio of maximum width T1 to minimum width T2 is 1 <
A range of TI/T2≦300 is possible. This ratio is 30
If it is larger than 0, it is necessary to make the size of the supply hole corresponding to the large forming groove extremely small, making machining difficult.

The supply hole is provided at the intersection or ridge of the forming groove on the cylinder side of the forming machine, and its hydraulic diameter must correspond to the width of the forming groove.

That is, as shown in FIGS. 3 to 5, supply holes 3b, 3c, and 3d with large hydraulic diameters are connected to forming grooves 2b, 2c, and 2d with small forming widths, respectively, and forming grooves 2a with large forming widths, 2e has a supply hole 3 with a small hydraulic diameter.
a and 3e communicate through communication grooves 11a and lie, respectively.

In order for the ceramic clay to coalesce within the forming groove, the size, number and arrangement of the supply holes must be such that the forming groove is sufficiently filled with ceramic clay, while the depth of the forming groove is It is necessary to fill it with ceramic clay.

Next, a process of molding a ceramic honeycomb structure having a plurality of partition wall thicknesses using the molding die of the present invention will be described.

The ceramic clay in the cylinder 4 is first pressed and supplied to the supply hole 3 of the mold l by a molding machine.

Here, the ceramic clay of the supply holes 3a, 3e with a small hydraulic diameter is different from the supply holes 3b, 3c, with a large hydraulic diameter.
Since the inner wall of the supply hole receives a greater resistance than that of 3d, the flow velocity of the ceramic clay becomes smaller.

On the other hand, in the forming groove 2, the forming groove 2 has a large forming groove width.
The molding speed of the ceramic clay in a and 2e is higher than the molding speed of the ceramic clay in the molding grooves 2b, 2c, and 2d, which have small molding groove widths. That is, the extrusion molding speed of the ceramic clay on the front surface of the mold is controlled complementary to the dimensions of the supply hole 3 and the molding groove 2, and both the thick and thin parts of the partition wall are molded at the same extrusion molding speed.

Furthermore, communication holes 11 are provided in forming grooves 2a and 2e with large partition walls.
a. Ceramic clay supply hole 3 communicating through the lie
In a and 3e, since the communication path is bent before and after the communication holes 11a and iie, the ceramic clay flows in the horizontal direction twice, and the ceramic clay coalesces there with a large pressure force. An extremely sound ceramic honeycomb molded body as shown in Fig. 9 can be obtained, and then by firing, it can be used for pressure wave superchargers without cracks etc. as shown in Figs. 10 and 11. You can get a ceramic rotor.

The ceramic extrusion mold of the present invention is applied to extrusion molding of ceramic honeycomb structures. For example, ceramics are used in catalyst carriers and soot removal filters used for internal combustion engine exhaust gas purification, rotary heat exchangers for gas turbines, solid electrolyte diaphragms for batteries, superchargers, etc.
Cordierite, silicon nitride,
These include aluminate titanate, β-alumina, and zirconia.

Example A ceramic clay was prepared by adding a sintering aid, a molding aid, and a solvent to silicon nitride as the main component, and the ceramic extrusion molds were connected as shown in FIGS. 7, 8, and 4, respectively. A rotor for a supercharger was molded at a molding pressure of 200 kg/cm 2 using a honeycomb extrusion mold having grooves of "straight shape", "key shape", and "U-shape".

Next, the molded body was fired at 1800° C. for 2 hours in a nitrogen atmosphere to obtain the ceramic rotor shown in FIG.

Thirty test pieces each measuring 3 mm x 4 mm x 40+nm were collected from the parts of each fired body where the barrier thickness was large, that is, the parts corresponding to the molded parts in parts 2a in Figs. 4 and 7. , JIS-R-1601 (1981)
The four-point bending strength was measured. The measurement results are shown in Table 1.

Table 1 shows that when the communicating groove is U-shaped, the average strength is the highest and the variation in strength is the smallest.

In addition, when observing the fracture surface of the test piece, the fracture initiation point is a fine rack when the communicating groove is straight or hook-shaped, but no cracks are observed on the fracture surface when it is U-shaped. I couldn't. Therefore, it can be seen that the ceramic honeycomb structure formed by the base having the U-shaped communication groove is superior to the conventional one.

(Effects of the Invention) As described in detail above, according to the extrusion mold of the present invention, the hydraulic diameter of the ceramic clay supply hole communicating with the molding groove with a small barrier thickness is The communication groove of the ceramic clay supply hole communicating with the forming groove, which is formed larger than the hydraulic diameter of the ceramic clay supply hole communicating with the groove and having a large barrier thickness, is bent in a U-shape. As a result, a shearing force is applied to the ceramic clay, and as a result, they are combined with a large pressure force, which has the advantage that an extremely sound ceramic honeycomb structure can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a front view from the extrusion side of an extrusion molding die showing one embodiment of the present invention, and Fig. 2 is a front view from the extrusion side of an extrusion molding die showing another embodiment of the invention. , Fig. 3 is a cross-sectional view taken along line BB' in Fig. 2, Fig. 4 is a cross-sectional view of a molding die to which a metal plate is attached, which is another embodiment of the present invention, and Fig. 5 is a cross-sectional view taken along line A in Fig. 1. -A' sectional view, mutual view with the cylinder, Figure 6 is a front view of the conventional extrusion mold, Figure 7 is the 6th
Fig. 8 is a sectional view of a conventional mold; Fig. 9 is a front view of a ceramic honeycomb molded body formed according to the present invention; Figs. 10 and 11 are both shown in the book. FIG. 10 is a perspective view and FIG. 11 is a front view of an example of a ceramic rotor for a pressure wave supercharger produced using the molded body obtained according to the invention. 1... Extrusion mold 2.2a, 2b, 2c, 2d, 2e... Molding groove 3, 3a, 3b, 3c, 3d, 3e... Ceramic 4... Cylinder 5 of the molding machine...・Mold mounting is done by frame 5'...ring pieces 6, 6a, 6b, 6c, 6d, 6e-opening 7
...Metal plate...Ring 8'...Disc plate 9...Bolt 11a, lie...Communication passage clay supply hole Patent applicant Nippon Insulator Co., Ltd. Figure 3 Figure 4 Figure 5 Figure 7 Figure 8, 2e Figure 9

Claims (1)

[Claims] 1. In an extrusion mold for a ceramic honeycomb structure having a plurality of partition wall thicknesses and at least two or more through holes, a forming groove corresponding to the cross-sectional shape of the ceramic honeycomb structure and an intersection or ridge portion of the forming groove The hydraulic diameter of the ceramic clay supply hole communicating with the forming groove having a small partition wall thickness is larger than the hydraulic diameter of the ceramic clay supply hole communicating with the forming groove having a large partition wall thickness. A ceramic extrusion mold characterized in that a communication groove of a ceramic clay supply hole communicating with a forming groove having a large partition wall thickness and forming the forming groove is bent in a U-shape.