JPS5910289B2 - Extrusion die for honeycomb structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an extrusion die for a honeycomb structure used as a catalyst carrier for reburning by passing exhaust gas from an internal combustion engine, and in which the walls of each honeycomb hole constituting the structure are approximately evenly spaced. The object of the present invention is to provide an extrusion die that can extrude to a thickness of .

As shown in the cross-sectional view of Fig. 1, the conventional extrusion die of a honeycomb structure has a large number of parallel independent holes formed in the back surface, and a honeycomb-shaped communication hole in the front surface that communicates each of the independent holes. The cap 1 is filled with a flat plate-shaped thick metal body of uniform thickness as shown in the figure, and the back surface 2VC has a large number of independent holes 4 as shown in FIG. A communicating hole 5 is opened in the front surface 3 as shown in FIG. In most cases, it is submerged in water and hardened by the action of a hydraulic resin mixed into the clay. However, when extruding a honeycomb structure with a large pipe diameter of 100 mm ψ or more, the pressure feeding pipe 6
Due to the flow resistance of the inner wall of the mold 1, the speed of the clay press-fitted into the independent holes 4 from the peripheral and central portions of the mold 1 is slowed down, and the clay, which advances relatively quickly in the central portion, is transferred to the front surface. The absolute amount of clay extruded is large because it is extruded from the communication hole 5, and it decreases toward the periphery.
becomes thicker, and the cross-sectional area of the honeycomb holes c becomes smaller in inverse proportion to it.

For this reason, when reactant gas such as exhaust gas is passed through, undesirable phenomena occur such as the amount of gas passing through the central portion decreases or the passing speed increases compared to the peripheral portion. The present invention eliminates such defects in the extrusion die, and as shown in FIG. The communication hole 15 is formed as usual by forming a hole deep in the center and shallow in the periphery.

In this example, since the effect of suppressing the increase in the thickness of the honeycomb hole wall in the central portion is gradual, the depth of the central independent hole must be twice the depth of the surrounding independent holes. arise. As another example of the above, as illustrated in FIG. 6, the back surface 22 of the base 21 is made into a planar shape as before, the front surface 23 is bulged out in a spherical shape, and each independent hole 24 is made as before.
The communication hole 25 is formed deep at the center and shallow at the periphery.

In the case of this embodiment, the purpose is achieved by making the depth of the central communicating hole 25 approximately 40 (F6 more) than the peripheral depth. It is also possible to bulge out and form the independent holes and the communicating holes deep in the central part and shallow in the peripheral part.

The degree of spherical bulge on the back surface and/or front surface is determined so that the thickness of the valley honeycomb hole walls extruded from the communicating holes is almost even. It is determined experimentally based on specifications such as the thickness of the walls of the honeycomb holes formed in the structure and the size of the die, that is, the cross-sectional area of the honeycomb structure to be extruded. As exemplified above, the extrusion die of the present invention transfers the velocity difference between the velocity of the molding material along the inner wall of the pipe and the velocity moving through the center from the numerous independent holes on the back of the die to the communicating holes. The thickness of each honeycomb hole wall of the honeycomb structure is adjusted to the honeycomb shape by averaging the extrusion speed of the valley section at the front of the die without reflecting the difference in speed between the peripheral part and the center part during pressure feeding. It has a specific configuration that increases the extrusion resistance of the molding material in the central part so that it almost matches the cross-sectional shape of the hole, and thereby reduces the cross-sectional area of the honeycomb hole walls and the honeycomb hole due to the difference in extrusion speed. In addition, the extrusion die has the effect of increasing the strength of the central portion to prevent bending or breakage due to pressure, and increasing its service life.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional extrusion die, Fig. 2 is a rear view thereof, Fig. 3 is a front view thereof, and Fig. 4 exaggerates the defects of a honeycomb structure extruded with a conventional extrusion die. 5 is a sectional view showing one embodiment of the present invention, and FIG. 6 is a sectional view showing another embodiment. 11, 21... Base, 12, 22...
Back, 13, 23... Front, 14, 24...
...Independent hole, 15, 25...Communication hole.

Claims (1)

[Scope of Claims] 1. An extrusion die for a honeycomb structure configured to extrude molding material press-fitted from multiple parallel independent holes on the back side of the die from honeycomb-shaped communication holes on the front side of the die, wherein the back side of the die and the die are The thickness of the central part of one or both of the front surfaces is increased compared to the peripheral part, and the extrusion resistance of the molding material in the central part is increased to equalize the passing speed of the molding material in the central part and the peripheral part. An extrusion die characterized by the following features: 2. The extrusion die according to claim 1, wherein the center portion of the large number of parallel independent holes on the back surface of the extrusion die is formed deeper in the front direction than the peripheral portion. 3. The extrusion die according to claim 1, wherein in the extrusion die, the central portion of the honeycomb-shaped continuous holes in the front surface of the extrusion die is formed deeper in the rear direction than the peripheral portion.