JPS6130887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention solves the problem of internal density difference due to flow resistance when extracted from a die, which is a major drawback and obstacle when forming a plate-shaped ceramic molded body from a raw material composition of kneaded plastic ceramic. This invention relates to a method for molding a molded body having a uniform internal structure as a whole with a certain directionality determined by distribution and orientation of particles.

In general, ceramic raw material compositions are mainly made of clay material with flat crystal grains, and when the water content increases, a hydrated film is formed on the particle surface, and when external force is applied to this with a clay kneader, plastic flow occurs. The flat particles are oriented in a layered manner in the direction of flow, sandwiching a water film as shown in FIG. 1A.

Furthermore, when the ceramic raw material is pulled out into a predetermined shape from the die using a kneading machine, etc., the flow resistance of the ceramic raw material in contact with the die is extremely large, resulting in a large density difference between the surface layer and the inside of the molded body, which causes internal strain. It is the cause. These conditions are shown in Figure 1 B and C. These orientations and internal distortions are due to differences in shrinkage depending on direction during the process of drying or firing to manufacture products, and partial bonding due to non-uniform density. There are defects such as cracks, deformation, and irregular dimensions, which have made it particularly difficult to manufacture large-sized plate-shaped products.

As mentioned above, this invention is a method of partially dispersing the internal strain from a non-uniform molded body that has internal strain caused by many elements to a molded body having uniform density and orientation as a whole. . An example of these methods will be explained using a diagram. As shown in FIGS. 1B and 1C, a plate-shaped raw material dough 2 extracted from a clay kneading machine nozzle 1 follows a flow trajectory shown by a curved line. Orientation and density differences, such as those shown by straight lines and differences in their spacing, are extracted as a non-uniform structure. In particular, as shown in FIG. 2A, the present invention applies a heterogeneous fabric 2 between a pair of rollers 3 and 4 having spiral grooves on their surfaces fed in opposite feeding directions toward the center. When the dough is pinched and rolled, the curved flow locus and orientation line that were present at the time of extraction are subdivided into small parts in the direction of the rolling center line of the dough 2, for example, 5 and 6, as shown in FIG. 2B.
The dough is re-kneaded into a scale-like shape to form a composition with uniform density and orientation as a whole, and is finally finished using a roller with a smooth surface (not shown) to form the required board. A shaped ceramic molded body is obtained. The scale-like shape and size vary depending on the groove-like shape of the roller and its rotation speed. If necessary, a homogeneous composition with further subdivided internal strain can be obtained by repeating rolling with a pair of rollers having spiral grooves several times. Furthermore, the method of obtaining a desired plate-shaped product from a fluid composition by roller rolling is a method widely used industrially, as seen in plate glass, steel products, synthetic resin products, etc.
In particular, the method for ceramic molded bodies was published in the patent application period.
50-24967. As mentioned above, the feature of the method of this patent is that in order to eliminate the defects mainly due to the orientation characteristic of the ceramic assembly raw material composition, ``rolling is carried out by alternating directions at 90 degrees with respect to the drawing direction.'' This method is characterized by the fact that simply rolling the entire surface perpendicular to the orientation line as in this method has little strain dispersion effect, and it takes more than 10 rolls to obtain the desired molded product. There is a point where rolling must be repeated by switching to alternate directions.

This invention is characterized by the synergistic effect of the twisting effect of the roller with spiral grooves and the rolling effect, which divides the dough into small parts and performs strong strain dispersion. This method has the great advantage of efficiently achieving the desired objective without conversion.

[Brief explanation of the drawing]

FIG. 1 is a sectional view, FIG. 2A is a side view, and FIG. 2B is a plan view. 1... Soil kneading machine mouthpiece, 2... Extracted plate-shaped raw material dough, 3 and 4... Pair of rollers having spiral grooves, 5 and 6... Scale-shaped plastic dough.

Claims (1)

[Claims] 1. When molding a clay-like plastic ceramic raw material composition into a plate shape by extracting it from a die, one or more pairs of rollers having spiral surface grooves feeding in mutually opposite directions toward the center of the rollers are used. A method for forming a plate-shaped ceramic molded body, which includes a step of rolling a composition by sandwiching the composition between the two.