JPS61244505A - Extrusion molding device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an extrusion molding machine, and particularly to an apparatus suitable for improving the quality and yield of thin-walled, complex-shaped products.

<Conventional techniques and their problems> Among ceramic molded products, the panel lamination method, paper dipping method, pipe bundling method, and sintering reaction method are used for molding thin-walled and complex-shaped products such as non-nicum type catalyst carriers. , press method, extrusion method and casting method. Among these, the extrusion method is suitable for mass production because various shapes can be molded depending on the shape of the die, and continuous molding is possible, and is currently widely applied.

An extrusion molding machine commonly used in the extrusion method is shown in Figure 4. The equipment includes bag mill 24°, auger machine 25. It can be classified into a column ring 21 connected to the body 1 of the auger machine and a forming die 4. Bag mill 24 is for raw material powder and binder.

By deaerating and kneading plasticizer, water, etc., it has the function of creating a material (elastoplastic fluid composed of solid and liquid) suitable for molding. The clay produced by the bag mill 24 is sent to the auger machine 25. Auger machine 2
5 has the function of consolidating the prepared clay and extruding it to the pillar ring 21 at a constant speed. In addition, 15 is screw 1
6 is a drive motor, 18 is a vacuum side, 17 is a deaeration port, 19 is a screw, and 20 is a drive motor.

The clay column at the outlet of the auger machine exhibits a swirling flow due to the rotation of the auger screw 20, and as a result, the clay becomes a laminate. In other words, lamination occurs in the clay due to this swirling flow. This lamination may cause defects such as cracks and remain in the molded product, so in order to prevent this defect, a pillar ring 21 is installed upstream of the molding die and the lamination is crimped. However, the occurrence of lamination defects largely depends on the properties of the clay, and therefore, it is necessary to set the length of the pillar ring each time to suit the clay, or to create a tapered shape.

Furthermore, since the fluid to be extruded belongs to an elastoplastic fluid, there is a pressure difference in the radial direction within the columnar ring.
The area near the inner wall of the pillar ring is higher than the center. As a result, the water in the soil moves toward the center of low pressure, resulting in clay with a non-uniform moisture content. As a result, when the green body is dried, the shrinkage becomes non-uniform, and the peripheral portions dry and shrink faster, making it easier for cracks to occur in the central portion. Furthermore, while the central part of the pillar ring exhibits a uniform flow velocity, the flow velocity rapidly decreases near the inner wall of the pillar ring.

As mentioned above, extrusion molding machines have inherent drawbacks, and when these are applied to the molding of thin-walled, complex-shaped products, the above-mentioned drawbacks are exacerbated, leading to the serious problems described below. further occurs.

One of them is the radial pressure distribution 2. Because of the existence of velocity distribution and moisture distribution, it is necessary to optimize the properties of the clay, the length of the pillar ring, and the flow path shape of the molding die by adjusting them. In particular, even a slight change in the properties of the clay causes a difference in the velocity of the flow extruded from each channel, resulting in the formation of a honeycomb molded body with distorted properties, making it impossible to manufacture a product that can withstand use.

When using the honeycomb structure as a catalyst carrier, it is desirable to form the ribs of the honeycomb as thin as possible in order to improve the activity of the catalyst and reduce the pressure loss of the gas passing through. For example, the rib thickness is o, 5mm
The front and back are in good condition. A problem in forming such a thin honeycomb structure is that a forming die with an extremely narrow flow path must be used. In other words, by narrowing the flow path, bulky debris existing in the soil,
To avoid clogging the channel with dried clay etc. adhering to the surface of the auger barrel, a honeycomb molded body with missing lattices is often extruded.

(*I'+7 These are practically unavoidable.QAs mentioned above, extrusion molding has the inherent drawback that the properties or behavior of the clay becomes non-uniform. When molding products, the quality and yield of the products are adversely affected.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the drawbacks of the above-mentioned conventional techniques and to provide a molding method and an apparatus therefor that are suitable for improving the quality and yield of thin-walled, complex-shaped products produced by extrusion. be.

Summary of the Invention> In short, the present invention provides a resistor such as a wire mesh in the center of the column ring located between the auger machine and the molding die of a conventional extrusion molding machine, and prevents the radial direction generated within the column. The structure is designed to alleviate the pressure distribution, velocity distribution, and moisture distribution of soil, and to remove coarse foreign matter mixed in the soil.

Example of implementation Examples of the present invention will be specifically described below.

FIG. 1 shows an embodiment of the present invention.The main part of the present invention is in a pillar ring installed downstream of the auger body 1, and in the center of the pillar ring, a wire mesh 9 of, for example, about 40 meshes is used as a uniform dispersion. It has a structure that allows it to be installed and easily replaced even while extruding the internal fluid. The functions of this wire mesh and its peripheral equipment will be described in detail below.

As described above, the clay upstream of the column ring portion has a pressure distribution, a moisture distribution, and a velocity distribution in the radial direction of the auger body. The porous plate 1 for fixing the wire mesh has the soil 14 exhibiting such behavior located between the upstream column ring 2 and the downstream column ring 6.
When pushed into the wire mesh 9 fixed by 1, the clay exhibits the following behavior. Near the upstream of the wire mesh 9, the center is near the inner wall of the column ring.Since the flow velocity is high, when the clay is pushed into the wire mesh 9 and folded, the center becomes high pressure, and the moisture in the clay flows from the center in the radial direction. move towards. On the other hand, in the downstream part of the wire mesh, as in the conventional device, the water in the second flow part of the wire mesh moves toward the periphery, so the amount of water movement in the soil is offset and equalized.

Next, the pressure loss of the clay is approximately proportional to the square of the flow velocity, so the high flow velocity at the center of the pillar ring passes through the wire mesh and is rectified downstream of the wire mesh, resulting in a change in flow velocity distribution. With the non-uniformity alleviated, it heads to the molding die 4. At this time, when the clay passes through the wire gauze, it is divided into fine pieces and recombined in the downstream area, resulting in a fine crosstalk effect.

Furthermore, coarse foreign matter contained in the clay in the wire mesh is removed, and a good honeycomb molded body 16 can be obtained.

Even if the wire mesh becomes clogged, the downstream post ring 6 provides a run-up distance l to the molding die 4, and the mechanism is such that it is compacted again, so there is little direct effect on the molded product. However, if used for a long period of time, a considerable amount of large-diameter particles may get caught in the wire mesh, leading to the risk of deformation or damage to the molded product. In this case, remove the inner wire mesh and replace it.

Cleaning is required.

To specifically show the wire mesh replacement structure, the downstream column ring 2 and the downstream column ring 6 are connected by a hinge 12, and the column ring 6 rotates in the The structure is such that the arranged wire mesh 9 is exposed. In addition, code 8 is Q IJ ring for sealing.

10 is a wire mesh support ring. In addition, both pillar rings 2 and 3
is always hook 6, stopper 7. They are arranged in close contact by the lever 5 and are integrally constructed. Note that the wire mesh 9 is attached to the support ring 1o using the stopper 2 on the wire mesh side.
6 to the support ring 1o with screws 22 [see FIG. 2(B)].

In order to maximize the effect of the wire mesh described above, the width of the opening of the wire mesh should be equal to or less than the minimum channel width of the die 4.
Even assuming that the length of the coarse foreign matter is 0.9, the minimum flow path width is 9
It may be set to 0% or less.

In addition, since the main purpose of the perforated plate 11 for fixing the wire mesh is to support the wire mesh, it is preferable to use one with as little pressure loss as possible, but it is also preferable to increase the porosity of the forming die, and the porosity should be 04 or more. Good.

If the aperture ratio is less than this, the discharge pressure from the auger machine will be attenuated in the perforated plate, and if a die with high flow resistance such as a honeycomb forming die is used, extrusion may become impossible.

Furthermore, in order to enhance the effect of the wire mesh, it is important to set the distance l of the downstream post opening located at the downstream part of the wire mesh to an appropriate dimension. The downstream column ring 6 is provided for the run-up section before the clay leaves the wire mesh 9 and enters the forming die 4, but the ratio of the length l to the inner diameter d of the downstream column i3, that is, l/d If l/d is small, the mesh of the wire mesh will directly lead to damage to the molded body, and conversely, if l/d is large, the boundary layer on the inner wall of the downstream column will be sufficiently developed, and the rectification effect of the wire mesh will disappear. do. This limit value differs depending on the soil, so it is difficult to define it, but if l/d < 6.2, the molded body will have frequent defects, and if l/d > 2, the specific plug radius at the column ring exit will decrease. (the radius of the main flow part that is not covered by the boundary layer) becomes extremely small, and the rectification effect of the wire mesh disappears. Therefore, in the present invention, the value of l/d is 0.2 <, l/d (2
Even more preferable conditions are 0.
5 < l/d × 15.

Table 1 As specific examples and comparative examples of the present invention, the results of studies conducted under the conditions shown in Table 1 are shown in Table 2, and the contents will be explained in detail below.

(Specific Example 1) A wire mesh of 42 meshes (350 μm) is fixed with a perforated plate with an aperture ratio of 0.5 (hole diameter filter, Qmm), and a straight pipe type with l/d = 0.5 is fixed at the downstream part. A honeycomb was formed using a device equipped with a downstream post ring. In this case, a honeycomb of 3 m or more could be continuously formed without any defects in the formed body. Furthermore, the surface condition was good and no cracks occurred even during drying. When the wire mesh was removed after molding, dried clay had adhered to several places, causing clogging.

(Comparative Example 1) This was based on a conventional method, and was molded using a device in which an upstream column ring and a molding die were directly connected. In this case, the molded body is 0
．． When it was extruded for about 5m, defects started to occur inside.
It was extruded as a distorted molded body. Furthermore, when we air-dried a healthy compact at the start of extrusion, we found that a crack had occurred in the middle of the nicum in the direction perpendicular to the flow path (
Specific Example 2) The wire mesh and perforated plate were the same as those in Specific Example 1, and the downstream column ring portion was short <l/d=o, D5. As a result of molding with this apparatus, the occurrence of defects in the molded product was 0.6 m or less, which was a large difference from Comparative Example 1, that is, when no wire mesh was used. However, the surface condition was good. No cracking occurred during drying.

On the other hand, when the wire mesh was taken out after extrusion, foreign matter was found adhering to it, but when the part of the molded body defective in the molding die was examined, nothing that appeared to be foreign matter was found.

(Comparative Example 2) A wire mesh of 60 meshes (250 μm) was fixed with a perforated plate with an aperture ratio of 0.7 (hole diameter 1.7 mm), and a straight pipe with 1/d = 0.5 was used as the downstream pillar ring. As a result of using the molded product, there were no problems with chipping or dry cracking of the molded product, but the bag mill of the extrusion molding machine generated heat.

(Comparative Example 6) A wire mesh of 20 meshes (840 μm) was fixed with a perforated plate with an aperture ratio of 0.7 (hole diameter Q, 7 mm), and a straight pipe with l/d = 0.5 was used as the downstream pillar ring. As a result of using it, the molded body was 1
．． A breakage occurred after being extruded for about 5 m. However, no dry cracking occurred. On the other hand, when the wire mesh and molding die were examined after extrusion, the flow paths of both were found to be clogged with foreign matter.

Effects> Since the present invention is configured as described above, the flow velocity distribution of the internal fluid such as clay is made uniform, and the moisture distribution is also made uniform, so that a good molded product can be obtained, and drying is possible. There will be no cracking afterward.

Further, since foreign matter in the internal fluid can be removed, defects do not occur, and it is possible to sufficiently cope with the increasingly complex shape of the molded body.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of an extrusion molding apparatus showing an embodiment of the present invention, Fig. 2(A) is a front view of a wire mesh, and Fig. 2(B) is a (A
), Figure 6 (A) is a front view of the perforated plate, Figure 6 (B) is a cross-sectional view of Figure 6 (A) along line B-B, and Figure 4 is a conventional extrusion molding device. FIG. 2..."Second stream side column ro...Downstream column ring 4...
・Honeycomb forming die 9...Wire mesh 11...Perforated plate for supporting wire mesh 14...Kneading soil L day 4

Claims (1)

[Claims] 1. In an apparatus for obtaining a molded product by disposing a molding die at the outlet of the columnar ring and extruding an internal fluid supplied inside the columnar ring through the die, A uniform dispersion material such as a wire mesh is arranged so as to be almost perpendicular to the direction of movement of the fluid.
An extrusion molding apparatus characterized in that the flow velocity distribution and water content distribution of the internal fluid in the circumferential direction of the column ring are configured to be uniform. 2. The extrusion molding apparatus according to claim 1, wherein the uniform dispersion is a wire mesh, and the wire mesh is supported by a perforated plate. 3. The method according to claim 1 or 2, characterized in that the pillar ring is divided in the uniform dispersion arrangement portion to facilitate replacement of the uniform dispersion arranged in the pillar ring. Extrusion molding equipment. 4. Claim 1, characterized in that the ratio l/d of the distance l from the uniform dispersion to the molding die and the inner diameter d of the columnar ring is 0.2<l/d<2. The extrusion molding apparatus according to any one of items 1 to 3.