JPH0527586B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing ceramic products, and more particularly to a method for manufacturing large, thin, plate-shaped ceramic products.

[Conventional technology]

In general, as a manufacturing method for ceramic products with three-dimensional shapes, small cylindrical products are molded using potter's wheel molding, and products with complex shapes are produced using plaster molds, which utilize the water absorption properties of the plaster molds to form slurry. This is done by slurry casting, which involves supplying the material to the mold surface and allowing it to absorb water and form.

[Problem that the invention seeks to solve]

Ceramics and other ceramics have excellent physical properties such as heat resistance and chemical resistance, and by making chemical experiment table tops and draft chamber tops using these ceramic materials, you can create products with excellent physical properties and high durability. It is possible to create a top plate for a laboratory table. However, such ceramic products have the disadvantage that when they are three-dimensional and thick, they are very heavy. Therefore, when making desk tops etc. from ceramics, a relatively thin ceramic top plate is layered on top of the core material, which reduces the weight of the top plate structure and improves heat resistance. Attempts are also being made to create laboratory desk top plates and draft chamber top plates with good chemical resistance. The shape of such a top plate is such that a protruding strip is provided around the upper surface of the top plate, a recessed portion opening downward is provided inside the protruding strip, and the position is fixed on the substrate through the recessed portion. However, in the conventional manufacturing method described above, potter's wheel molding can only form small, cylindrical items, and large, especially plate-shaped items such as the desk tops and draft chamber tops mentioned above cannot be formed. Cannot be molded. In addition, in casting molding methods using plaster molds, when molding large and thin products, in order to uniformly inject the slurry material into the mold, many slurry injection ports are provided, and the slurry is Although slurry is injected and filled into the mold in a short time by applying pressure, the deposition on the mold surface tends to be uneven, which not only causes deformation and cracks after firing, but also In the case of products with large drying shrinkage during firing, it is difficult to obtain the desired product dimensions. It has been difficult to manufacture a flat plate-like product having a protruding strip around the circumference having a concave portion opening downward with high dimensional accuracy.

In view of the above-mentioned problems with the conventional method of manufacturing ceramic products, the present invention has been developed to produce a flat plate with protrusions around the periphery, for example, for the top plate of a laboratory table in chemistry or the top plate of a draft chamber. In addition, as a manufacturing method for a ceramic product having a shape in which the convex portion has a downwardly opening concave portion, the mold surface is uniformly deposited to prevent deformation and cracking after firing, and the dimensional accuracy is high. It is an object of the present invention to provide a method for manufacturing flat ceramic products that can be used to manufacture ceramic products.

[Means for solving problems]

In order to achieve the above object, the present invention is made by molding a thin plate of ceramic clay onto a lower table made of a water-absorbing material and using a material that is also water-absorbing as the lower table. The drying shrinkage when the dough is baked is used as an auxiliary mold, and a frame mold that can be separated and made into a split mold is placed on the upper surface of the mold that is movably installed on the lower stand, and is crimped onto the mold surface. The present invention provides a method for manufacturing a flat ceramic product having a convex strip having a downwardly opening concave portion on its lower surface, which is characterized in that the ceramic product is molded, dried and hardened, and then the auxiliary mold is removed from the mold and fired. That is.

[Effect]

The gist of the method for manufacturing a ceramic product according to the present invention is as described above, and the method is as follows. When manufacturing ceramic products, the ceramic clay used as the dough is formed into a thin plate shape, then placed on the top of the mold and crimped to the mold surface, so that the entire surface can be uniformly inked. In addition to preventing deformation and cracking after molding, the shrinkage of the product during firing can be compensated for by forming using a split mold that can be separated in advance as an auxiliary mold to compensate for drying shrinkage during firing. It is possible to obtain a product with high dimensional accuracy, and when the product is fired, the frame mold is moved on the lower stand, and the auxiliary mold is separated and removed before firing, so that the auxiliary mold does not get in the way during firing. This allows the product to be molded without disturbing the shrinkage of the product and causing product distortion during molding.

[Details of the invention]

To explain the present invention in more detail, the composition of the ceramic clay used in the present invention must have sufficient plasticity to be molded into a thin film and press-bonded to the mold surface. The content of plastic clay such as Kibushi clay or Frogme clay in the composition is preferably 50% or more. Further, in order to smoothly perform operations such as forming into a thin plate shape or pressing onto the upper surface of a mold, a deflocculant such as sodium silicate or sodium phosphate may be appropriately added to the composition.

Next, as the material for the mold, water-absorbing materials are used to reduce the difference in drying speed between the front and back surfaces of the molded product and to prevent distortion of the molded product. It is preferable to use
For example, calcium silicate, gypsum, etc. are used as the mold material. In addition, when manufacturing ceramic products, the drying shrinkage during molding is large, and especially when molding large and long items, the shrinkage dimensions are extremely large, so the dimensions of the mold must be adjusted to shrink due to drying. It is necessary to set the size to be larger than the product size in consideration of the weight. Since such drying shrinkage is usually 4 to 5%,
In the present invention, a convex strip having a concave portion opening downward is formed around the flat plate using a frame mold in which an auxiliary mold of a size that can be corrected by the above proportion from the product dimensions is added as a split mold and can be separated. This makes it possible to obtain highly accurate product dimensions. For example, if the required product dimension is L1 and the drying shrinkage rate during molding is α, an auxiliary mold can be attached to the outside of the frame with L1 dimension. The overall dimension L2 of the frame mold in the installed state is
It is sufficient to set it so that L2=L1×(1−α/100). In addition, in the present invention, the dough is pressed and molded onto the mold surface set as described above, and after drying and hardening, the auxiliary mold is removed and baked. By allowing the auxiliary mold to shrink and fire naturally without losing its shape when demolding, and without interfering with the shrinkage action of the molded body during firing, it is possible to prevent internal stress from occurring in the product due to shrinkage distortion. This makes it possible to eliminate the causes of deformation and cracks after firing and to obtain products with high dimensional accuracy.

In the manufacturing process described above, in order to equalize the drying speed of the front and back sides of the fabric when drying and hardening the fabric pressed onto the mold surface, a material with good water absorption such as calcium silicate or plaster is used as the mold material as described above. It is something. Furthermore, if the drying method is rapid drying such as hot air drying, there will be a large difference in the drying speed between the front and back sides of the fabric, which can easily cause deformation or cracks in the formed product. By performing slow heating drying using far infrared rays, it is possible to reduce the difference in drying speed between the front and back sides of the fabric, thereby preventing deformation and cracking of the product after molding.

After the molded body is dried and hardened as described above, the frame mold is moved together with the molded body on the lower stand, the frame part is positioned outside the lower stand, the auxiliary mold is removed from the molded body, and necessary finishing and repairs are carried out. After performing, the firing temperature, e.g.
Bisque firing is performed at a temperature of approximately 1200℃. After bisque firing, a finishing process is performed, and a predetermined glaze is applied to the surface of the bisque fired product, followed by glaze firing to provide a surface finish and provide a finished product.

In order to prevent deformation during glaze firing, it is desirable to perform the glaze firing at a temperature that is at least 10°C lower than the temperature during bisque firing, and the glaze firing is usually performed at a temperature of approximately 1100°C. Furthermore, the thermal expansion coefficient of the glaze is +0 to 10×10 ^-7 /℃ higher than that of the base material.
By making small adjustments within a certain range, it is possible to obtain a product with higher dimensional accuracy.

An example of manufacturing a ceramic product using the method for manufacturing a ceramic product according to the present invention as described above will be described below.

Embodiment FIG. 8 shows a vertical sectional side view of a laboratory desk that employs a top plate produced using the method for manufacturing ceramic products according to the present invention. A top plate 2 manufactured by the method for manufacturing a ceramic product according to the above is employed.

As shown in the figure, the upper part of the experimental table main body 1 is
Rectangular in plan view, such as plywood or other wood boards,
Or a substrate 3 made of a material such as an inorganic board
A supporting protrusion 4 is provided on the periphery of the core material 5 to form a core material 5. The support protrusion 4 of the core material 5 can be made of the same material as the substrate 3 and protruded integrally, but it can also be provided with a separate member provided thereon. The illustrated supporting protrusion 4 is made of synthetic resin foam, typically urethane foam. A top plate 2 is attached to the surface of the core material 5, and the top plate 2 is made of ceramics such as ceramics, and is relatively thin as shown in the figure.
For example, a material having a thickness of about several millimeters is used, and a protrusion 7 having a recess 6 on the lower surface that can be fitted externally into the supporting protrusion 4 of the core material 5 is provided around the periphery, and an interior surrounded by the protrusion 7 is provided. A recess 8 for the surface of the top plate is formed in the top plate, and the top plate 2 is placed on the core material 5, and the recess 6 opened downward on the lower surface of the protrusion 7 is fitted onto the supporting protrusion 4. The top plate 2 and the core material 5 are bonded together by appropriately interposing an adhesive or the like to form the top plate portion as shown.

Top plate made of ceramics such as those mentioned above 2
To create this, as shown in FIG. 1, a convex strip 7 is formed around the top plate 2 on the upper surface 11 of a lower base 10 made of a water-absorbing material such as calcium silicate or plaster. An inner mold 12 made of a water-absorbing material such as calcium silicate or gypsum is placed in the same manner as the lower stand 10, and has a rectangular frame shape when viewed from above. An outer mold 13 which is separable at the corner and is separable from the inner mold 12 is provided as an auxiliary mold for shrinkage correction on the inner mold 12, and the inner mold 12 and the outer mold 13 form a A frame mold 14 for forming a protruding strip 7 having a downwardly opened recess 6 disposed around the periphery is formed, and the frame mold 14
The upper surface 11 of the lower base inside the frame 14 is configured as a mold for forming the top plate 2, and is made of ceramic clay into a thin plate shape with a thickness required for the top plate 2, for example, several millimeters. The molded dough 15 is coated on the mold surface from above and pressed using a rubber roller, a trowel, etc., so that the frame mold 14 as the protruding strip 7 and the lower base upper surface 11 portion inside the frame mold 14 are coated. A flat internal plane portion as the recess 8 is formed, and a peripheral wall 17 for preventing the dough from sagging is formed on the outside of the outer mold 13 to form a top plate-shaped molded body 16. Further, in the manufacturing method according to the present invention, a thin film-like sheet extending from the inside of the frame 14 to the outside of the mold 14 is provided between the frame 14 and the molded body 16 on the upper surface 11 of the lower table 10 and the upper surface 11 of the lower table. By laying the strip sheet 19 vertically and horizontally across the frame 14 on the entire surface of the lower stand 10, or as shown in the illustration, after drying and hardening the molded body 16, the molded body 16 is placed on the lower stand together with the frame 14, as described later. The outer mold 1 is moved on the upper surface 11 until the frame mold 14 is positioned outside the side edge 18 of the lower stand 10.
3 is released, and the outer mold 13 serving as an auxiliary mold can be removed from the mold.

Molded body 16 in the shape of two top plates formed as described above
(Fig. 1, Fig. 4) is cured by gentle heating and drying with far infrared rays, etc., and then the above-mentioned belt-shaped sheet 19 is pulled to the side by holding the portion exposed outside the frame 14. The molded body 16 is molded into the frame mold 14 by
At the same time, the upper surface 11 of the lower base 11 is moved until the outer mold 13 portion of the frame mold 14 reaches a position outside the side edge 18 of the lower base 10.
By moving the position above (Fig. 2), the outer mold 13
The space below the part is released, and the outer mold 13 is demolded downward from the released part (FIG. 5). This operation is performed sequentially on each of the four sides of the molded body 16, and all the outer molds 13 serving as auxiliary molds on the four sides are demolded. As shown in FIG. 3, the position of the molded body 16 can be moved by moving the molded body 16 not in the lateral direction but in the diagonal direction.
3 and 13' can be simultaneously moved to the outer position of the lower stand 10 and both the outer molds 13 and 13' can be removed from the mold at the same time, and the positional movement of the molded body 16 can be completed in two steps.
Molded object 1 after removing the outer mold 13 in this way
6 is again placed on the upper surface of the lower stand 10 (FIG. 6), and bisque fired at a firing temperature, for example, about 1200° C., in an electric furnace or the like.

The dimensions of the mold 14 in the above molding process are, for example, when the width of the top plate 2 is l1, the distance between the outer edges of the inner mold 12 constituting the frame mold 14 is l1, which is the width of the top plate 2. In order to repair the expected drying shrinkage rate α, for example, 5%, l2=l1(1-
0.05), the width of the molded product after molding can be approximately l1 (Fig. 7).

After repair processing such as cutting out the peripheral wall 17 is performed on the unglazed product fired in this way, it is heated to about 1100°C and contains sodium oxide, calcium oxide, zirconium oxide, silicon oxide, or aluminum oxide as a component. The top plate 2 is created by applying a ceramic glaze that melts and becomes vitrified and firing the glaze at a temperature lower than the unglazed firing temperature, for example, at a temperature of about 1100°C to prevent deformation during glaze firing. This is what happens.

As described above, the desk top plate 2 produced by the method of manufacturing a ceramic product according to the present invention can be used as a desk top plate 2 used in chemical experiments etc. because it is lightweight and has the heat resistance that ceramics such as ceramics have. In addition to being strong and chemical resistant, the core material 5 is positioned on the underside of the top plate 2 and has a laminated structure, which improves impact resistance, which is generally a drawback of thin-walled ceramics and ceramics. Therefore, it is possible to provide a laboratory desk top plate 2 which is lightweight, has excellent heat resistance and chemical resistance, and also has good impact resistance.

Further, as in the embodiment of the above manufacturing method, when forming the molded body 16 on the lower stand 10, by laying a sheet material such as a belt for moving the molded body 16 in advance, the molded body after drying can be This makes it easier to move the outer mold 16 together with the frame mold 14, and the outer mold 13 can be easily removed from the mold.

In FIG. 8, reference numeral 20 is a liquid discharge port for waste liquid and the like provided in the recessed portion 8 of the upper surface of the desk top plate 2, and 21 is a trap connected to the liquid discharge port 20.

〔Effect of the invention〕

As described above, the method for manufacturing a flat ceramic product according to the present invention involves placing a fabric formed into a thin plate of ceramic clay on a lower table made of a water-absorbing material, which also has water-absorbing properties. A frame mold made of a material made of drying shrinkage when the dough is fired is used as an auxiliary mold, and a frame mold made of a separable and split mold is placed on the upper surface of the mold, which is movably installed on the lower table. It is characterized by being pressed onto the mold surface and molded, dried and hardened, and then removed from the auxiliary mold and fired.The ceramic clay used as the dough is pre-formed into a thin plate shape and then placed on the top of the mold. By press-bonding it to the mold surface, the entire mold can be uniformly deposited on the upper surface of the mold, preventing deformation and cracking after molding, and the drying shrinkage during firing can be added in advance as an auxiliary mold so that it can be separated. Since the molding is performed using a frame mold configured as a split mold, it is possible to compensate for shrinkage of the product during firing and obtain a product with high dimensional accuracy.Furthermore, the auxiliary mold can be removed from the mold when firing the product. Since the auxiliary mold gets in the way during firing and prevents the shrinkage of the molded product and causes product distortion during molding, it is possible to mold the product. As a manufacturing method for a ceramic product in the shape of a thin flat plate with a convex strip surrounding the periphery having a concave portion opening downward, the ceramic product prevents deformation and cracking after firing and has high molding dimensional accuracy. It is possible to provide a manufacturing method for ceramic products that can manufacture ceramic products.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the method for manufacturing ceramic products according to the present invention, and is a perspective view showing a molded body placed on a lower table, and Fig. 2 shows a state in which the molded body is moved on the lower table. FIG. 3 is an explanatory plan view showing an example of the method of moving the molded body on the lower table, FIG. 4 is a side sectional view of the molded body on the lower table, and FIG. 5 is the A side cross-sectional view showing how the molded body is moved on the lower table and the outer mold is removed from the mold, and FIG. 6 is a side cross-sectional view showing the molded body returned to the lower table after the outer mold is removed from the molded body. Fig. 7 is a side sectional view showing a molded body in a state of shrinkage after firing, and Fig. 8 is an example of a laboratory desk using a top plate formed using the method for producing ceramic products according to the present invention. FIG. 1: Desk body, 2: Top plate, 3: Substrate, 4: Support protrusion, 5: Core material, 6: Recess, 7: Convex strip, 8: Recess, 10: Lower part, 11: Upper surface of lower stand, 12: Inner mold,
13: Outer mold, 14: Frame mold, 15: Fabric, 16: Molded body, 17: Peripheral wall, 18: Lower stand side edge, 19: Band top sheet, 20: Liquid discharge opening, 21: Trap.

Claims (1)

[Claims] 1. A fabric formed into a thin plate shape using ceramic clay,
On a lower stand made of a water-absorbing material, a frame mold made of a water-absorbing material similar to the lower stand, and made into a split mold in addition to the drying shrinkage when the dough is baked, is used as an auxiliary mold and can be separated. The auxiliary mold is placed on the upper surface of the mold movably installed on the lower table and pressed against the mold surface to form the mold, and after drying and hardening, the auxiliary mold is removed from the mold and fired. A method for manufacturing a flat ceramic product comprising a protruding strip having a concave portion opening therearound. 2. A method for manufacturing a ceramic product according to claim 1, which uses a ceramic clay containing 50% or more of plastic clay.