JPH0722927B2 - Tile press molding and drying method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for press-molding and drying tiles, and in particular, it is possible to prevent variations in products and to manufacture tiles with high dimensional accuracy. Moreover, the present invention relates to a tile press molding method capable of preventing cracks during drying and improving yield.

[Prior Art] A tile is manufactured by forming a tile raw material (kneaded clay for forming), firing it, and then performing glaze and glaze firing as necessary. In general, dry molding is used for molding. Tile raw material is put between the upper mold and the lower mold to move the fixed mold (usually lower mold) to the movable mold (usually upper mold). ) Is moved and the tile raw material is pressed between the fixed mold and the movable mold to be molded. Conventionally, such press molding is performed by applying a certain pressure to a certain amount of raw material, and specifically, about 50 t is generally applied to a material having a size of 108 × 108 mm. Target.

The press-molded body is glazed if necessary, and then
Dry and bake. A hot air dryer is widely used to perform this drying.

[Problems to be Solved by the Invention] In a conventional press molding method in which a certain amount of tile raw material is pressed with a constant pressure, the size of a molded body obtained by fluctuation of the water content of the tile raw material and the firing There is a drawback in that the dimensions of the resulting sintered body vary, and a product with high dimensional accuracy cannot be obtained.

That is, since the tile raw material is prepared using clay or the like which is a natural mineral, even if the tile raw material is prepared with the same composition, the water content thereof greatly varies depending on the place of origin of the used raw material. Further, even with the same prepared raw material, the water content varies depending on the difference in storage environment or the storage period. For example, when examining the water content of each batch of spray kneaded clay for mosaic tiles, as shown in Fig. 1, the average water content of 375 samples x was 7.1%. And the maximum moisture content is 2.4%.

In this way, when tile materials with different water contents are always pressed at a constant pressure, naturally tile materials with a high water content have a large compression ratio and are sufficiently pressed to form a compact with a small thickness. Become. Therefore, the product tile obtained by firing has a small thickness. On the other hand, the tile raw material having a low water content has a smaller compressibility and a larger thickness than the tile material having a high water content is pressed.

Therefore, the product tile is also relatively thick. In this way, the thickness of the product tile varies due to the difference in the thickness of the molded body formed by press molding. Moreover, due to the difference in compression rate during press molding, there is a difference in the density of the molded body,
For this reason, the amount of baking tightness at the time of baking differs, and as a result, a large variation occurs in the size of the product tile. For example, a tile raw material having a high water content is highly compressed into a high-density molded body by press molding, but the high-density molded body has a small firing shrinkage, and thus becomes a sintered body having a large planar dimension. On the other hand, since the tile raw material having a low water content is formed into a compact having a relatively low density by press forming, the firing shrinkage is large, and thus a sintered body having a small plane dimension is obtained. Moreover, the difference in the density of the molded body causes warpage and product defects under constant firing conditions, and further causes variations in water absorption rate, strength, etc.
Therefore, the yield of the product is significantly reduced.

Further, according to the hot air drying device, the molded body is likely to be cracked. In particular, in the accessory tile as shown in FIG. 5, cracks are likely to occur in the L-shaped corner portion. It is considered that the reason why the molded body is cracked is that only the surface is dried by hot air drying, and water is likely to remain in the core portion.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a tile press-molding method capable of producing tiles having high characteristics with high dimensional accuracy and high yield.

[Means for Solving the Problems] A method of press-molding and drying a tile according to the present invention is a method of press-molding a tile raw material between a fixed mold and a movable mold and then drying the tile material, wherein the movable mold has a constant stroke length. It is characterized in that it is made into a stroke and is press-molded, and is also microwave-dried.

As a method of moving the movable die by a constant stroke length, for example, a method of suppressing the stroke length using a linear scale or the like can be adopted.

2 to 4 show an example of the structure of the microwave drying device 10.

The drying device 10 puts a tile molded body 12 in a setter 14 made of aluminum, and conveys the tile molded body 12 on a conveyor 16 to dry the molded body through a heating unit 18.

The heating unit 18 includes a casing 20 lined with glass wool and a metal plate, an inspection window 22 is provided on a side surface of the casing 20, and three exhaust fans 24 are provided on a ceiling portion. . Reference numeral 26 is a small hot air blower, which allows hot air to be blown into the casing 20 through the hot air blowing port 28. 30 is an electronic blower and 32 is a sirocco fan.

A microwave irradiation mechanism is provided in the casing 20. Microwave shields 34 and 36 are installed at the inlet and outlet of the casing 20, respectively.

38 is a motor for driving the conveyor 16, and 40 (FIG. 1) is a turntable for changing the setter direction.

The tile molded body 12 placed in the setter 14 is introduced into the casing 20 from the right side of FIGS. 2 and 3, heated in the microwave and dried while moving leftward in the figure. Hot air is blown into the casing 20 as needed to promote drying. The exhaust fan 24 also discharges the moist air.

The dried compact is sent out of the casing 20 together with the setter 14, the direction of the setter 14 is changed by the turntable 40, and sent out of the drying device 10.

[Operation] In the method of the present invention, since the movable die is stroked by a constant stroke length and press-molded, the thickness of the tile raw material is not affected by the moisture content of the tile raw material, and the thickness of the tile raw material is constant. It is possible to obtain a tile molded body having a constant density.

For this reason, the shrinkage of the obtained tile molded product is also constant, and a product tile having no variation in size, quality, etc. is manufactured by baking.

Further, by performing microwave drying, it is possible to uniformly heat the entire molded body including the core of the molded body. For this reason,
It is possible to prevent cracking due to residual water.

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 A spray kneaded clay for a mosaic tile having a water content distribution shown in FIG. 1 was used as a tile raw material, 62 g of which was used as an upper mold (movable mold).
Between the lower mold and the lower mold (fixed mold) and press-molding with the lowering stroke of the upper mold always constant at 7 mm to obtain a molded product of accessory tile having the dimensions shown in FIG. Second
It dried with the drying apparatus 10 shown in FIG. In addition, this drying apparatus is provided with 18 500-W microwave irradiators. The residence time in casing 20 was 3 minutes and 24 tiles were dried per minute. 1255 dried molded body
Calcination was performed for 1 hour. The dimensions and the like of the obtained fired body were measured, and the results are shown in Table 1. In addition, Table 1 shows the yield due to drying (no crack generation).

Comparative Example 1 The same procedure as in Example 1 was repeated except that the press-forming pressure was set to 140 Kg-f / cm ² instead of the lowering stroke of the upper mold. The dimensions of the body were measured and the results are shown in Table 1.

It is clear from Table 1 that according to the method of the present invention, the tiles can be manufactured with high dimensional accuracy and high yield by preventing dimensional variations among products.
The number of samples is 240 in Example 1 and 1250 in Comparative Example 1.

[Effects of the Invention] As described in detail above, according to the tile press-molding and drying method of the present invention, it is possible to manufacture a tile-molded product having no variation in size, density, and the like with a high yield. Therefore,
By firing a tile molded body with such constant dimensions and density, it is possible to produce high-quality tiles with high quality and dimensional accuracy under constant firing shrinkage conditions. Is also greatly improved.

[Brief description of drawings]

FIG. 1 is a graph showing the water content distribution of tile raw materials.
2 is a plan view of the microwave dryer, FIG. 3 is a front view of the same, and FIG. 4 is a right side view of the same. FIG. 5 is a perspective view of the tile molded body.

Claims (1)

[Claims] 1. A method of press-molding a tile raw material between a fixed mold and a movable mold, followed by drying, in which the movable mold is stroked by a certain stroke length and press-molded, and heated by microwave to dry. A method for press-molding and drying a tile, which comprises: