JPH0872036A - Method and mold for molding large-sized thin ceramic plate - Google Patents

Abstract

PURPOSE: To mold a large-sized thin ceramic plate, the density of which is uniform and in which no crack due to internal strain or the like develops. CONSTITUTION: Pug-like plastic ceramic composition W as starting stock is extrusion-molded with a vacuum extrusion molding machine or pug mill 11 into a molded body Wa having the shape such as square column, cylinder or the like and then formed under pressure with a pressing machine 13 so as to remove internal strain and be shaped into a pressure-molded body Wb having uniform density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a large and thin ceramic plate body and a molding die thereof, including interior and exterior tiles mainly used for building materials and other various ceramics.

[0002]

2. Description of the Related Art Conventionally, as a typical method for molding a large-sized ceramic flat plate, there is dry press molding in which powder is pressed. In this case, a large flat plate, for example 900
2,000 to form a flat plate of 900 mm size
A molding pressure of ton or more is required, which causes a large-scale manufacturing facility and causes a cost increase. Further, in the case of this dry press molding, as the product becomes larger, various measures are required at the time of charging, pressurizing, and demolding the raw material powder in order to ensure the uniformity of the density of the molded body, As the process control becomes more complicated and the size becomes larger, the cycle time becomes longer and the cost is increased. Furthermore, when trying to form a plate having the same size and a wall thickness of 8 mm or less, for example, the uniformity of the density of the plate,
It was almost impossible in terms of handleability of the plate.

Another molding method is a cast molding method (slip casting molding method). However, this cast molding method has a long cycle time and is difficult to automate, so that it is cost effective. However, even if you try to mold a large and thin plate with this method, the density of the plate will not be uniform. It was the current situation that there are almost no cases in which the plate body of (1) is manufactured.

Then, as a method for forming a large-sized and thin-walled plate body, there is a roll rolling method which has been most frequently used in recent years. As a method for forming a large and thin plate by this roll rolling method, for example, there is one disclosed in Japanese Patent Laid-Open No. 51-34213. The method disclosed in this publication is a method in which plastic soil is extruded by a vacuum kneader into a shape having a circular curve, then opened into a flat plate shape, and this flat plate is rolled by rollers to form a flat plate. However, in this case, during extrusion molding, it is difficult to completely remove the density difference and internal strain caused by the difference in flow resistance between the die and the plastic soil, and therefore, for example, in Japanese Patent Publication No. 61-30887. The method is being developed.

The method disclosed in JP-B-61-30887 is a method of removing internal strain by rolling with a pair of rolling rollers 1 and 2 having a spiral groove 3 as shown in FIG. .

Further, the one disclosed in Japanese Patent Publication No. 50-24967 discloses that a portion cut from a material bar is first passed through a pair of rolls in at least the flow direction, and then 90 ° to the original direction. The plastic lumps, which are characterized by passing through a pair of rolls in the same direction, are extruded into rods by an extruder and made into individual pieces, which are passed several times between the pair of rolls, and the length and thickness of the panel with a wide surface. It is a method of extending so as to conform to.

Further, there is the one disclosed in Japanese Patent Application Laid-Open No. 1-258904, and the technical content disclosed in this publication is, as shown in FIG. 7, a ceramic raw material composition W having plasticity after kneading. The cylindrical molded body 6 extruded from the cylindrical die 5 of the vacuum extruder 4 is longitudinally cut into a plate-shaped body 7, and the plate-shaped body 7 is rolled in the same direction as the extrusion direction. 8 through a pair of rolls 8 having spiral grooves 9 having feeds in mutually opposite directions toward the center line to form a plate-shaped molded body 7a having a predetermined thickness, and then a rolled molded body 7a. A plate-shaped molded body 7 which is rolled and molded in the same manner as above.
This is a method in which b is overlapped so that the rolling directions a are perpendicular to each other, and the rolled formed body 10 is passed through the rolling roll 8 again to be formed into a rolled compact 10 having a predetermined thickness.

[0008]

However, in the method of extruding this plastic soil into a shape having a circular curve with a vacuum clay kneader, expanding this into a flat plate, and rolling with a rolling roll, the vacuum soil is used. When extruding with a kneader, it is difficult to remove the difference in density and internal strain caused by the difference in flow resistance, and various developments as described above have been made to remove it. Therefore, in the rolling process with the rolling rolls, several types of rolling rolls must be passed, and the process becomes extremely complicated,
Further, there is a problem that a manufacturing line is complicated because process operations such as rolling by rolling a plurality of rolled compacts and rolling by changing the rolling direction by 90 degrees are required.

The present invention has been made to solve the above-mentioned conventional problems, and provides a method and a mold for molding a large-sized thin ceramic plate body having a uniform density and free from cracks and the like due to internal strain. It is intended to be provided.

[0010]

In order to solve the above technical problems, the present invention uses a kneaded clay-like plastic ceramic composition as a starting material, and the starting material is processed by a vacuum extrusion molding machine or a vacuum kneading machine. A large-sized thin-walled ceramic plate body that removes internal strain and is molded into a pressure-molded body having a uniform density by pressure-molding a molded body extruded into a columnar shape, a cylindrical shape, or another shape with a press machine. It is a molding method, and is also a molding die for a large-sized thin ceramic plate body in which the molding surfaces of the upper and lower molds of the press machine are formed by a substantially air-permeable member having air permeability.

[0011]

By performing pressure molding of the molded body molded by the vacuum extrusion molding machine or the like as described above, it is possible to remove the internal strain and mold it into a pressure molded body having a uniform density. In addition, since the upper and lower mold surfaces of the press are formed of a ventilation member that is substantially permeable to air, air entrapment during the pressure molding process is prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a schematic view of a forming process of a large thin ceramic plate according to the present invention.
Is prepared by previously mixing a ceramic raw material composition and other raw materials with water in a predetermined amount, and the water content at this time is preferably 20 to 30% based on the weight of the dry raw material powder. Figure 1 (a) shows a vacuum extruder or vacuum clay kneader 1.
1, the clay-like plastic ceramic composition W is extruded from the molding machine 11 through the die 12 into a molded body Wa having a predetermined shape. The shape of the molded body Wa in this case is not particularly limited, and various shapes such as extruding into a columnar shape, a prismatic shape or a cylindrical shape and expanding the cylindrical molded body into a flat plate shape can be used. In this example, as shown in FIG. 1 (b), a prismatic shape was used for illustration. At the time of this extrusion molding, a sufficient degree of vacuum is secured as in the case of molding by a normal vacuum extrusion molding machine, and molding is performed so that bubbles and the like do not remain in the molded body Wa to be molded.

The molded body Wa thus molded is placed on the lower mold 15 of the pressing machine 13 composed of the upper mold 14 and the lower mold 15 (FIG. 1 (c)), and the upper mold 14 is predetermined. By lowering with a stroke of and pressing the compact Wa (FIG. 1 (d)), the compact Wa has a predetermined thickness t and is molded into a substantially circular pressure compact Wb ( Figure 1 (e)). In this case, press machine 13
The structure is not particularly limited as long as the molded body Wa can be pressure-molded to a predetermined thickness t.

The pressing machine 13 shown in FIG.
The structure shown in FIG. 2 includes the upper mold 14, the lower mold 15, and the frame 16 as shown in FIG. 2, which is used in the conventional dry press molding.
In the process of rolling the compact Wa, the mold 1
Since the molded body Wa is blocked by 6 and the flow of the molded body Wa is restricted so that the molded body Wa cannot be molded to a predetermined thickness t, the outer peripheries of the upper and lower molds 14 and 15 have an open structure without the form frame 16. Is desirable. However, if the shape of the molded body Wa before pressing is taken into consideration so that the molded body Wb is not blocked by the mold 16 when the molded body Wa is rolled into the molded body Wb having the predetermined thickness t, the Molding is also possible with the press machine 13 including the upper mold 14, the lower mold 15, and the mold 16 shown in FIG. In this case, the molding surfaces 14a and 15a do not necessarily have to be flat, and it is possible to give unevenness patterns to the surface of the pressure-molded body Wb by giving unevenness, for example. Deformation is possible.

Then, as shown in FIG. 1 (f), the outer peripheral portion of the pressure-molded body Wb is cut, cut into a substantially rectangular shape as shown in FIG. 1 (g), and dried in the drying step. . In addition, by the above method, the composition of the stoneware tile base material is formed into, for example, a width of 800 mm, a length of 1200 mm, and a thickness of 4 mm, and dried until the water content becomes 1% or less.
As a result of dividing into small pieces of mm square and measuring the bulk specific gravity of each, a bulk specific gravity (n = 50) of 1.91 standard deviation (σn-1) 0.0126 was obtained. The measuring method is based on JIS R2205, and kerosene was used as the medium liquid. From these measurement results, it can be seen that the pressure-molded body Wb has a very small variation in bulk specific gravity and a uniform density.

In this way, the plastic ceramic composition W in the form of kneaded clay is extruded into a prismatic shape, a cylindrical shape or any other shape, and this compact Wa is press-molded and pressure-molded to a predetermined thickness t. A large, thin ceramic flat plate with a width of 800 mm, a length of 1200 mm, and a thickness of 4 mm is formed into a body Wb and is cut into a predetermined shape. The result was that there were very few defects such as deformation and cracking.

Therefore, according to this example, there are the following merits as compared with the conventional method. That is, a large-sized and thin ceramic flat plate, which cannot be formed by the conventional dry press molding, can be formed by a low pressing force. That is, for example, when a pressure molded body Wb having a width of 800 mm, a length of 1200 mm and a thickness of 4 mm is to be molded by the dry press molding method (although it cannot be molded by dry press molding), Although a molding pressure of 2000 to 3000 tons or more is required, according to the method of this example, the pressurizing pressure can be about 500 tons, and the density of the press-formed body Wb at this time is also extremely uniform.

Also, since the substantial press-molding time is completed in a few seconds, the cycle time is shortened, which is advantageous in terms of cost.
This is extremely advantageous as compared with the case where it takes about 10 minutes to complete the forming of a flat plate of mm.

Further, as in the conventional method in which plastic soil is extruded into a shape having a circular curve by a vacuum kneading machine, this is spread into a flat plate shape, and this is rolled by a rolling roll, the density is nonuniform. , A vacuum extrusion molding machine or a vacuum clay kneader 1 which does not require a rolling operation for removing internal strain
A flat plate having a uniform density and free from deformation and cracks due to drying can be obtained only by press-molding a molded body Wa extruded from No. 1.

The effects of the method of the present invention will be described below.
In general, a ceramic composition having plasticity is mainly composed of a clay-like raw material having flat crystal particles, so if this is extruded by a vacuum extrusion molding machine or the like, a molded body is formed due to the flow resistance of the die of the molding machine and the plastic soil. Internal strain is generated in the surface layer portion and inside. Therefore, when a large and thin flat plate is extruded, dried and fired, the internal strain causes deformation or cracking easily from the outer peripheral portion of the product. Therefore, in order to remove this internal strain, it is rolled with a rolling roll, but the plastic soil at the interface with the roll, compression, tension, shear stress acts intricately, new internal strain on the molded body after rolling. Is easy to generate. Further, as a characteristic of the rolling roll, the dough moves only in the advancing direction and hardly moves in the direction perpendicular to the advancing direction, so that the obtained molded body has stronger anisotropy than the extruded molded body before rolling.

In this respect, in the present example, since only the extruded columnar, prismatic or other shaped body Wa is pressed by a vacuum extrusion molding machine or the like, only the compressive stress is applied to the same composition Wa. Does not work. Also, the upper and lower mold 1
When press-molded with Nos. 4 and 15, the composition Wa is uniformly spread in all directions, so that the anisotropy of the kneaded material during extrusion molding is relaxed to some extent. Therefore, the molding by the press machine 13 does not require a complicated operation for dispersing the internal strain such as by using a rolling roll, and the molded body Wa after the extrusion molding can be formed into a large size with a uniform density without distortion by only a single pressing operation. It can be made into a thin plate.

Next, the upper and lower molds 14 and 15 of the press machine 13 will be described. Generally, a kneaded clay-like plastic ceramic composition is extruded into a prismatic shape, a cylindrical shape, or another shape, and is pressed by a press machine 13 to form a large-sized thin-walled press-formed body Wb. The molds 14 and 15 are made of a metal material such as iron.

Therefore, the upper and lower molds 14 made of this metal material,
When a rectangular columnar shaped body Wa having a cross-sectional shape of 10 cm on each side is extruded by a vacuum extruding machine by 15 to a thickness of 4 mm, as shown in FIG. Annual ring-shaped wrinkle-like cracks 17 were generated on the surface, and there was a problem that it could not be used as a product. As shown in FIG. 9, the generation of the annual ring-shaped wrinkle-shaped cracks 17 causes the compact Wa to be thinly extended in the process in which the compact Wa is pressed by the upper and lower molds 14 and 15. The contact area between the dough and the molding surfaces 14a and 15a of the mold is increased. In the process of expanding the contact area, air entrapment occurs in the process of pressing and moving the part where the forming surfaces 14a and 15a do not come into contact with the kneading clay, that is, the outer peripheral part of the kneading clay where the contact expands. It is considered that the same air remains in the compact Wa, and as a result, annual ring-shaped wrinkle-like cracks 17 are generated.

Therefore, the molding surface 1 of the upper and lower molds 14 and 15
4a and 15a are formed of a permeable member that is substantially permeable to air. That is, as shown in FIG. 3, the upper and lower molds 14 and 15 are entirely made of, for example, a porous ceramic, gypsum,
The ventilation member 18 is made of synthetic resin. Also,
In the structure shown in FIG. 4, the ventilation members 18 made of, for example, a porous ceramic, gypsum, or synthetic resin having a predetermined wall thickness are attached to the molding surfaces 14a, 15a of the metal upper and lower dies 14, 15, respectively. It is a thing. Further, the structure shown in FIG. 5 is configured such that an air ventilation member 19 having a predetermined thickness, such as a cotton cloth that is substantially permeable to air, is attached. Therefore, by forming the molding surfaces 14a and 15a with these ventilation members 18 and 19, the air is not entrained in the molded body Wa during the pressure molding by the press machine 13. It is possible to escape through 19 and prevent the generation of annual ring-shaped wrinkle-like cracks on the surface of the pressure-formed body Wb.

[0025]

INDUSTRIAL APPLICABILITY The present invention uses a clay-like plastic ceramic composition as a starting material, and the starting material is extruded into a prismatic shape, a cylindrical shape or another shape by a vacuum extruder or a vacuum kneader. This is a method for forming a large-sized thin ceramic plate body that removes internal strain by pressing the molded body with a press machine and molds it into a pressure molded body with a uniform density. A large and thin ceramic flat plate that could not be molded can be molded with low pressure. Further, since the substantial press-molding time is completed within a few seconds, the cycle time is shortened, which is advantageous in terms of cost, and the production efficiency can be improved. Further, a conventional plastic soil is extruded into a shape having a circular curve by a vacuum kneading machine, developed into a flat plate shape, and like a method of rolling this with a rolling roll, a non-uniform density, an internal strain of A flat plate with uniform density and without deformation or cracking due to drying can be obtained by simply press-molding a molded product extruded from a vacuum extruder or vacuum kneader without requiring a rolling operation for removal. You can In addition, by forming the upper and lower molding surfaces of the press machine with a substantially air-permeable member having air permeability, annual ring-shaped wrinkles due to the inclusion of air on the surface of the pressure-molded product molded by the press machine. It is possible to prevent the occurrence of cracks and improve the quality of the final product.

[Brief description of drawings]

1 (a), (b), (c), (d), (e), (f), and (g) are schematic views of a forming process of a large-sized thin ceramic plate according to the present invention.

FIG. 2 is a structural diagram of a press machine including an upper mold, a lower mold, and a mold.

FIG. 3 is a cross-sectional view in which the entire upper and lower molds of the press machine are formed of a ventilation member such as porous gypsum, synthetic resin, or ceramic that allows air to pass therethrough.

FIG. 4 is a cross-sectional view in which the upper and lower mold surfaces of the press machine are formed with a ventilation member such as porous gypsum, synthetic resin, or ceramic that is permeable to air.

FIG. 5 is a cross-sectional view in which the molding surfaces of the upper and lower molds of the pressing machine are formed by a ventilation member such as cotton cloth that is permeable to air.

FIG. 6 is an explanatory diagram of rolling of plastic soil with a conventional spiral grooved roll.

FIG. 7 is a process diagram of forming a conventional compact of a plastic soil extruded by a vacuum extrusion molding machine into a large-sized thin ceramic plate by a rolling roll.

FIG. 8 is a perspective view of a pressure-molded body in which wrinkle-shaped cracks are generated.

FIG. 9 is a cross-sectional view illustrating generation of wrinkle cracks.

[Explanation of symbols]

 11 vacuum extrusion molding machine, vacuum clay kneading machine 13 press machine 14 upper mold 14a upper mold molding surface 15 lower mold 15a lower mold molding surface 18, 19 ventilation member

Claims (2)

[Claims] 1. A kneaded clay-like plastic ceramic composition is used as a starting material, and the starting material is extruded into a prismatic shape, a cylindrical shape, or another shape by a vacuum extrusion molding machine or a vacuum clay kneader to press the molding. A method for forming a large-sized thin ceramic plate body, in which internal strain is removed and a pressure-formed body having a uniform density is formed by pressure-forming with a machine. 2. A molding die for a large-sized thin ceramic plate body in which the molding surfaces of the upper and lower molds of a press are formed by a substantially air-permeable member having air permeability.