JP2564086B2 - Extruder core metal structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core metal structure of an extrusion molding machine for extrusion-molding a cylindrical molded body made of ceramic clay.

[0002]

2. Description of the Related Art In order to produce a cylindrical body or the like made of ceramics, water, an organic binder, etc. are added to the ceramic material powder, if necessary, and this is kneaded, and the kneaded product is formed into a cylindrical shape. There is a need to. As a molding method, an extrusion molding method is mainly used because of its high productivity.
In such an extrusion molding machine, in order to mold the hollow portion in the cylinder of the cylindrical molded body, it is necessary to fix the core metal at a predetermined interval inside the die. That is, a molding port is formed between the die and the core, and the thickness of the cylindrical molded body is controlled by the distance between the die and the core.

[0003]

In such a base structure, the present applicant first fixed the core to the core support member,
A technique for fixing the cored bar support member near the base with a support arm has been disclosed (Japanese Patent Application No. 3-245842). In this technique, for example, three flat plate-shaped support arms are used, and a cored bar support member is supported at the center of each support arm. The ceramic cup clay passes through the gaps between the three support arms, and then this ceramic cup clay is extruded from the forming port between the die and the core.

However, in this way, inside the extruder,
It has been found that the following problem occurs when the core metal is held by the flat plate-shaped support arm. . That is, the ceramics clay passes through the gap between the flat plate-shaped support arms and is then extruded from the annular molding port between the die and the core, for example, the shape schematically shown in FIG. It becomes the cylindrical molded body 30. However, when the cylindrical molded body 30 is fired, the cracks 31 extending in the longitudinal direction may become visible. The position of the crack 31 corresponds to the position of the support arm described above, and is caused by the cutting of the clay by the support arm.

An object of the present invention is to provide an extrusion molding machine for producing a cylindrical molded body by extruding ceramics clay through a molding opening between a die and a core. When supporting the core metal, it is to prevent cracks due to the above-mentioned supporting portion from appearing when the tubular molded body is fired.

[0006]

The present invention relates to a core metal structure of an extrusion molding machine used for forming a cylindrical molded body by extrusion molding ceramics clay, which comprises at least a core metal.
This core has a supporting portion for fixing it to the inner surface of the extrusion molding machine, and has a cross-sectional shape when the supporting portion is cut in the extrusion direction of the ceramics clay. The present invention relates to a cored bar structure of an extruder, in which the thickness of the support part gradually decreases from the thickest part of the support part toward the downstream side.

[0007]

EXAMPLE FIG. 1 is a sectional view showing the structure around a die of an extrusion molding machine, FIG. 2 is a front view showing a core bar supporting member 4 used in the die structure of FIG. 1, and FIG. It is a sectional view taken along line III.

First, an example of the structure of the base will be described.
In the present embodiment, the mouthpiece structure is formed by the mouthpiece 2 and the mouthpiece support member 1. The mouthpiece support member 1 includes a flange 1a having a ring-shaped outer shape, and a tip portion 1b protruding concentrically from the flange 1a. Flange 1a
A through hole 1c is provided inside the tip portion 1b.

The base 2 also has a ring-shaped flange 2
a, and a tip portion 2 projecting concentrically with the flange 2a
b is provided. A through hole 2c that penetrates the flange 2a and the tip portion 2b is also formed. The inner contour of the mouthpiece support member 1 and the outer contour of the mouthpiece 2 are formed so that they can be in close contact with each other without a gap. Then, the base 2 is positioned with respect to the base support member 1 by inserting and fitting the base 2 into the through hole 1c of the base support member 1. At this stage, the base support member 1 and the base 2 can be separated.

The tip side of the core metal 3 has a columnar shape, and a truncated cone-shaped portion is formed at the base of this columnar portion. The outer contour of the core 3 is designed to be parallel to the inner contour of the base 2. A male screw 3 a is provided on the circular bottom of the cylindrical portion of the cored bar 3. The outer shape of the main body 4b of the cored bar support member 4 is a shape in which a circular bottom of a truncated cone is joined to a cone 4a which narrows in the opposite direction. A ring-shaped portion 4c is provided so as to surround the truncated cone-shaped portion of the main body 4b, and the main body 4b and the ring-shaped portion 4c are connected by the plate-shaped support portions 12 in three rows. The ring-shaped portion 4c is inclined toward the tip side.

Three gaps 11 are formed by the main body 4b, the ring-shaped portion 4c and the three rows of plate-shaped support portions 12. A female screw 4d is formed at the tip of the frustoconical portion of the main body 4b, and the male screw 3a is fitted to the female screw 4d to fix the cored bar 3 to the cored bar support member 4. The outer contour of the truncated cone-shaped portion of the cored bar 3 and the outer contour of the truncated cone-shaped portion of the cored bar support member 4 are smoothly connected with almost no step. In the present embodiment, by the core metal 3 and the core metal supporting member 4,
A core metal structure is formed.

As a result, the cored bar 3 is fixed to the inner surface of the extrusion molding machine by the three plate-shaped support portions 12 via the main body 4b of the cored bar support member 4. Although the cored bar 3 and the cored bar support member 4 are separate bodies in this embodiment, the cored bar 3 and the cored bar support member 4 can be formed as an integral part.

Next, the ring-shaped portion 4c of the cored bar support member 4
The outer peripheral surface of is fitted into the through hole 5a of the ring-shaped jig 5. The through hole 5a is slightly recessed toward the tip, so that the through hole 5a and the ring-shaped portion 4c can be fitted to each other. At this point, the ring-shaped jig 5 and the cored bar support member 4 can be easily separated by pulling them in opposite directions.

Next, the core metal support member 4 and the ring-shaped jig 5 are fitted into the through holes of the die structure and temporarily fixed. In this state, the core 3 is fixed in the through hole 2c of the base 2, and the molding port 6 is formed between the base 2 and the core 3.
The ring-shaped portion 4c contacts the end surface of the flange 2a of the base 2. Each void 11 communicates with the molding port 6. Ring jig 5
Are fitted into the recess of the flange 1a without any gap.

In this embodiment, the intermediate body 8 has a cylindrical main body and flanges 8a formed at both ends of the main body.
8b. This flange 8a, the flange 1a,
The flanges 1a and 8a are fastened to each other with bolts or the like in alignment with the end faces of the ring-shaped jig 5 and the ring-shaped portion 4c. As a result, the base 2, the ring-shaped jig 5, and the core support member 4 are sandwiched between the base support member 1 and the flange 8a. The conical portion 4a of the main body 4b projects into the inner space 7 of the intermediate body 8.

Then, the flange 9a of the main body 9 to which the auger screw 10 is attached and the flange 8b are put together, and the both are fastened to each other with bolts or the like. This allows
The assembly of the die structure of the extruder is completed.

In operation, when the auger screw 10 is rotated, the ceramic clay is fed from the inside of the main body 9 into the inner space 7 of the intermediate cylinder 8. The clay flows in the direction of arrow A, hits the conical portion 4a of the main body 4b, flows toward the outer peripheral edge of the inner space 7, passes through one of the three voids 11, It is extruded between the die 2 and the core 3, and is extruded from the molding port 6 to the outside.

According to the present invention, in the sectional shape of the plate-shaped support portion 12 cut in the extrusion direction A of the ceramic clay, the plate-shaped support portion 12 extends from the thickest portion to the downstream side. The thickness of the plate-shaped support portion 12 is gradually reduced. Preferably, the thickness of the plate-shaped support portion 12 gradually decreases from the thickest portion of the plate-shaped support portion 12 toward the upstream side. Here, “decreasing gradually” means that the thickness becomes smaller as the distance from the thickest portion becomes larger.

Particularly, the plate-like support portions 12A and 12B having the sectional shapes shown in FIGS. 4 and 5 are preferable. However, in FIG.
The cross-sectional shape shown in FIG. 5 is the IV-IV line, V-V in FIG.
A cross section is shown when cut along a line. This IV-IV line, V
The −V line is parallel to the extrusion direction A.

In the plate-shaped support portion 12A shown in FIG. 4,
The cross-sectional shape is substantially symmetrical with respect to the center line D, and a pair of apexes 12c are provided slightly upstream of the center. The plate-shaped support portion 12A is thickest at the position of the pair of apexes 12c. From the pair of vertices 12c toward the downstream side and the upstream side, a substantially isosceles triangular shape is formed. A side 12d extending from the apex 12c to the downstream side is linear, and a flat surface 12e is provided on the most downstream side. The side 12b extending from the apex 12c to the upstream side is linear, and the plane 1 is located at the most upstream side.
2a is provided.

The sectional shape of the plate-shaped support portion 12B shown in FIG. 5 is similar to the sectional shape of the plate-shaped support portion 12A. However, the arcuate portion 12f is provided on the most upstream side, and the arcuate portion 12g is provided on the most downstream side.

The following effects can be obtained by adopting the above-mentioned supporting portion. That is, as shown in FIG.
As a result of the present inventors' investigation of the cause of the crack 31 extending in the longitudinal direction in the cylindrical molded body 30, the following has been found.

As shown in FIG. 6, a conventional plate-shaped support portion 22 is provided.
The cross-sectional shape of was almost rectangular. In this case, the ceramic clay that has flowed in the direction of arrow A is
Hitting 2a, splitting in two, flowing along side 22b,
It is joined again on the downstream side of the surface 22c. However, surface 22
Air tends to accumulate around c, which hinders the pressure of the cup soil flow and appears as cracks after firing.

However, when the cross-sectional shape is as shown in FIGS. 4 and 5, the cup soil flowing in the direction of arrow A has sides 12
flow along arrow b as indicated by arrow B, then along edge 12d as indicated by arrow C, plane 12e or arcuate portion 12
It is crimped at part g. At this time, since the cup soil flows along the side 12d, no air pool is generated, and since the two cup soil flows in the directions approaching each other, a high crimping force is applied during crimping. As a result, when the cylindrical molded body was fired, almost no cracks were formed.

Further, in the conventional plate-like support portion 22 shown in FIG. 6, the cup soil is retained on the upstream surface 22a and becomes hard soil having a small amount of water. Then, this hard soil is pushed by the flow of the clay and is peeled off, and is mixed into the clay again. As a result, a defective portion having less moisture than the surroundings remains in the cylindrical molded body, which causes a defective product.

In this respect, with the cross-sectional shapes shown in FIGS. 4 and 5, the cup soil flows along the side 12b as shown by the arrow B, so that the cup soil does not stay. Therefore, it is possible to prevent defective products due to the mixture of the hard soil once retained.

In each of the sectional shapes shown in FIGS. 4 and 5,
Furthermore, it is preferable to adopt the following dimensions. That is, side 12
The angle θ ₁ formed by b with the central axis D is preferably 15 to 45 degrees. If θ ₁ exceeds 45 degrees, the cup soil tends to accumulate.
The angle θ ₂ formed by the side 12d and the central axis D is preferably 15 to 45 degrees. If it exceeds 45 degrees, the cup soil tends to accumulate and cracks tend to remain.

The width n of the flat surface 12a and the arcuate portion 12f is
It is preferably 0.2 mm to 2 mm. When n was 2 mm or less, no retention of cup soil was observed. The width m of the flat surface 12e and the arcuate portion 12g is preferably 0.2 mm to 2 mm. When m was set to 2 mm or less, retention of cup soil was no longer observed.

If m is less than 0.2 mm, the knife edge will have a very sharp tip. In this case,
In rare cases, a crack may remain in the cylindrical molded body. The radius of curvature of the arcuate portions 12f and 12g is preferably 0.1 mm to 3 mm.

In the example of FIGS. 4 and 5, the sides 12b, 1
Although 2d is linear, these shapes may be elliptical, parabolic, sinusoidal, semicircular, or the like. The present invention can also be applied to extrusion molding of a tubular molded body having a square shape, a regular hexagonal shape, or the like in the width direction.

Hereinafter, more specific experimental results will be described. An extruder having the die structure shown in FIGS. 1 to 3 was produced (diameter 75 mm). However, the cross-sectional shape of the plate-shaped support portion was set as shown in FIG. 4, FIG. 5, or FIG. However, in the example shown in FIGS. 4 and 5, the lateral length in FIGS. 4 and 5 is 15 mm, and the distance between the pair of apexes 12c is 6 mm.
And θ ₁ was 40 degrees, θ ₂ was 20 degrees, m was 0.5 mm, and n was 1.0 mm. Arc-shaped part 12
The radius of curvature of f and 12g was 0.5 mm.

On the other hand, in the supporting portion 22 of the comparative example shown in FIG. 6, the side surface 22b has a length of 15 mm and a width of 6 mm.

84 parts by weight of high-purity alumina powder and 13 parts of water
An alumina clay consisting of 3 parts by weight of polyvinyl alcohol and 3 parts by weight of polyvinyl alcohol was produced. Extrude this alumina clay using the above-mentioned extrusion molding machine to obtain an outer diameter of 18 mm, an inner diameter of 13 mm,
Cylindrical compacts having a total length of 1500 mm were produced for each 50 pieces for each example.

As a result, when the plate-shaped supporting portion 22 having the cross-sectional shape shown in FIG. 6 was used, 20 of 50 had cracks 31 (see FIG. 7) in the subsequent firing step. In addition, in 5 out of 50, defects were generated in the cylindrical body due to inclusion of foreign matter.

On the other hand, the plate-like support portion 1 having the sectional shape shown in FIG.
2A, in the case of using the plate-shaped support portion 12B having the cross-sectional shape shown in FIG. 5, cracks 31 do not occur in the subsequent firing step in any of the 50 cylindrical molded bodies, and abnormalities due to inclusion of foreign matter also occur. I didn't.

[0036]

As described above, according to the present invention, in the sectional shape of the ceramic cup clay when the support portion is cut in the extrusion direction, the portion having the largest thickness of the support portion is located on the downstream side. The thickness of the support portion is gradually decreasing toward. Therefore, since the thickness is reduced in the most downstream portion of the support portion, air is less likely to accumulate in the downstream portion of the support portion,
It does not hinder the pressure of cup clay flow. Moreover, since the thickness of the support portion gradually decreases toward the downstream side, the two cup soil flows flowing on both sides of the support portion are flowing toward each other, and the two cup soil flows are close to each other. When joining, a high crimping force is applied. Therefore, even if the cylindrical molded body was fired, almost no cracks were formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a die structure of an extruder.

FIG. 2 is a front view showing a cored bar support member 4.

3 is a sectional view taken along the line III-III of FIG.

FIG. 4 is a sectional view showing a sectional shape of a plate-shaped support portion 12A.

FIG. 5 is a sectional view showing a sectional shape of a plate-shaped support portion 12B.

FIG. 6 is a sectional view showing a sectional shape of a conventional plate-shaped support portion 22.

FIG. 7 is a front view of a cylindrical molded body 30.

[Explanation of symbols]

 2 base 3 core metal 4 core support member 6 forming port 8 intermediate body 11 void 12, 12A, 12B, 22 plate-like support 12a, 12e plane 12c a pair of vertices (thickest part) 12f, 12g arc shape Part 30 Cylindrical compact 31 Crack A Extrusion direction of ceramics clay B, C Flow of ceramics clay

Claims (2)

(57) [Claims] 1. A core metal structure of an extrusion molding machine used for forming a cylindrical molded body by extrusion molding ceramics clay, comprising at least a core metal and the core metal in the extrusion molding machine. A supporting portion for fixing to the side surface, and in a cross-sectional shape when the supporting portion is cut in the extrusion direction of the ceramic clay, from the portion with the largest thickness of this supporting portion. The core metal structure of an extruder in which the thickness of the support portion gradually decreases toward the downstream side. 2. In the cross-sectional shape of the support portion cut in the extrusion direction of the ceramics clay, the thickness of the support portion increases from the thickest portion of the support portion toward the upstream side. The core metal structure of an extruder according to claim 1, which is gradually decreasing.