JPH0580321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a potter's wheel rolling method for ceramic clay, particularly a rotary trowel type rolling method, and a trowel used therein.

[Prior art] In the rotary trowel type rolling forming method, which is a typical example of the potter's wheel rolling forming method, in most cases, a metal material is used as a trowel material and contact rolling is performed by heating the metal material and the trowel. A water vapor film is generated in between to prevent the adhesion of the clay to the trowel and to maintain smooth contact between the clay and the trowel (hereinafter referred to as the heating trowel method;
6281). In other words, in the conventional rotary trowel type rolling forming method, a rotary trowel (roller) machined from an iron or aluminum material is heated (about 100°C) with a gas burner or an electric heater, etc., and the trowel and molding clay are heated during forming. It is rolled and formed while creating a film of steam in between.

[Problems to be solved by the invention] In the conventional method, the surface temperature of the solder metal is usually between 95℃ and 105℃.
℃ or less is suitable; if it is lower than this, clay will adhere to the trowel, and if it is higher than this, cracks will occur on the back of the molded product. Therefore, it is necessary to always maintain the above-mentioned constant temperature, but there are drawbacks such as the work of always maintaining the constant temperature requires skill and the work environment is poor due to heat radiation. Furthermore, if the trowel is kept in an overheated state, heat is transferred to the trowel attachment members (for example, levers or rods), and each attachment member is heated, resulting in the effect of thermal expansion, which disturbs the position between the mold and the trowel. This also causes an error in the axis of rotation between the mold and the iron. As a result, changes in the wall thickness of the molded product are unavoidable, resulting in problems such as deterioration of the precision of the shape of the molded product. Alternatively, if the proportion of clay in the clay is not within a certain range (approximately 20% by weight or more), cracks will occur, adhesion problems will occur, and stable molding will not be possible.Therefore, the heating trowel method is not universally applicable. It was difficult to say that it was a certain potter's wheel rolling method.

The present invention aims to solve these conventional problems.

[Means for Solving the Problems] First, the present invention uses a rolling trowel equipped with a ventilation hole with a diameter of 0.1 to 0.5 mm in a potter's wheel rolling method for ceramics, and blows gas from the surface of the trowel. To provide a potter's wheel rolling forming method for ceramics, characterized in that rolling forming is carried out while always forming a thin gas film between the clay and the trowel surface by blowing out the clay. Second, the present invention has a diameter
To provide a potter's wheel rolling forming trowel for ceramic clay, comprising a trowel body having a rolling forming surface having one or more ventilation holes of 0.1 to 0.5 mm, and a gas supply means for blowing out gas from the forming surface.

The trowel of the present invention is preferably a rotary trowel, but
It can also be used as a stationary trowel. Typically, the rotational axis of the trowel and the rotational axis of the potter's wheel intersect at a predetermined angle, and while rotating with each other, the clay placed between the trowel and the mold (fixed on the top surface of the potter's wheel) is rolled and formed.

The present invention uses a trowel with ventilation holes in the rotary rolling molding method for ceramics, and supplies gas (such as compressed air) to the trowel surface that contacts the clay to form a thin gas film. This prevents the clay from adhering to the trowel, and produces the same effect as when a normal heated metal trowel generates a water vapor film from the clay to prevent the clay from adhering to the trowel.

The present invention eliminates the limitations of the conventional methods described above, and uses a potter's wheel forming method that enables rotary rolling forming with very little incidental equipment.It can be used in a wide range of applications and enables universal forming that does not require skill. It is something.
However, the combined use of low-temperature heating (approximately 50 to approximately 60°C) with a trowel does not necessarily impede the present invention.

In the present invention, ceramics is interpreted in a broad sense, and can be applied to compression molding of other ceramic green molded objects including whiteware.

The specific configuration will be explained below. First, a trowel having ventilation holes reaching the molding surface is manufactured using plaster, plastic, metal, ceramic material, or a composite or laminated material of these materials to ensure a predetermined amount of ventilation. The diameter of the vent hole is 0.1-0.5 mm, and the gas pressure is adjusted accordingly. If the diameter of the ventilation hole exceeds 0.5 mm, scratches with a crater-like cross section will occur on the surface of the molded product, and if it is smaller than 0.1 mm, sufficient ventilation effect will not be obtained. The shape of the ventilation hole does not necessarily have to be a perfect circle, and beautiful skin can be obtained as long as the longest part of the hole does not exceed 0.5 mm. The number of ventilation holes cannot be unconditionally defined because it varies depending on the size, shape, required surface quality, etc. of the molded body, but one or more, preferably one to several, are provided. Preferably, one vent hole is provided in the center of the trowel forming surface, two vent holes are provided in the thread bottom, and at least several vent holes are provided in other locations.

The ejected gas may be any gas that is inert under the molding conditions, and usually air (preferably dry air) is used. As mentioned above, the ejection pressure varies depending on the diameter of the vent hole, the required molding quality, etc., but it is preferably in the range of 0.5 to 5 Kgf/cm ² , and the ventilation amount is 20 c.c./cm ² per unit area of the trowel molding surface.・Min or more, preferably 30c.c./
Ensure that cm ²・min or more. If the ejection pressure and the amount of air flow are less than this range, a sufficient gas film will not be obtained at the interface between the clay and the trowel, and if it exceeds this range, it will be difficult to obtain a smooth surface of the molded product.

The gas supply means for ejecting gas from the molding surface of the iron is not particularly limited, and for example, a normal gas supply device such as an air compressor can be used.

Next, the trowel forced rotation rolling method will be explained. For example, as shown in FIG. Install a trowel with ventilation holes. Next, the trowel material is rolled and formed while being rotated by an independent trowel drive device while supplying compressed air. At this time, the air ejected from the surface of the trowel forms a film between the surface of the clay to be rolled and the surface can be smoothed without the clay sticking to the trowel.

If the soldering material is made of plaster or the like, it is reinforced and attached with a holder, and if necessary, ribs are provided inside to ensure connection with the holder. An air supply port provided in the rotating shaft distributes gas to the breathable trowel via an air chamber or the like and causes it to be ejected from the molding surface. The shape of the air chamber can be appropriately selected depending on the size, material, and shape of the trowel, and branches can also be provided. In the rolling process of the present invention, the rotation of the trowel is generally in the same direction as the rotation of the potter's wheel (mold) and an appropriate circumferential speed difference is provided to produce the rolling effect. Depending on the conditions of the clay etc., the trowel may be rotated independently,
It can be used in rotation with a potter's wheel or in a stationary position, and is characterized by a wide variety of devices and uses. Therefore, it can be used in the rolling forming of ceramic materials in a wide variety of fields.

In the case of iron materials with sufficient strength such as sintered metal,
The holder 2 is not absolutely necessary and can also be fixed directly to the rotating shaft (usually to its end flange).

In addition, non-heating plastic trowels made of lubricating plastic materials such as molybdenum-added nylon require a difference of 50 to 100 rpm between the rotation speeds of the trowel and the potter's wheel, but with the present invention, the trowel does not have to be forced to rotate. It can also be molded. That is, free/driven rotation driven only by frictional resistance with the clay on the mold may be used.

Note that this trowel is not limited only to plates, but can also be used for rotary rolling forming of cups and balls.

[Example] Two ventilation holes with a diameter of 0.3 mm that penetrate the rotary iron 3A made of a dense metal material and reach the iron surface 3C are provided at the bottom of the thread.
Three pieces were provided at equal pitches around the outer periphery. Next, a chamber 4 is installed on the back side of the trowel face 3C, and dry air is introduced by 0.5
It is now possible to supply in the range of ~5Kgf/ ^cm2 .

Using this rotary trowel, various clays with a moisture content of 21 to 26% by weight (5 to 50% by weight of clay for imparting compositional plasticity,
A plate containing a predetermined amount of kaolin, quartz, and feldspar was used to roll and form a plate having a diameter of 6 to 10.5 inches and a main part thickness of 4 to 5 mm after firing.
The rotation speed of the potter's wheel is 320 to 360 rpm, and the rotation speed of the trowel is
300-340rpm (same direction), approx.
The molding operation was performed while blowing out dry air at 0.7 Nl/min, or approximately 1 Nl/min for an 8" pan. As a result, a molded product of superior quality was obtained compared to the conventional heating trowel.
It showed good quality even after firing.

Experiments have shown that if an 8-inch plate has an airflow rate of 15 l/min or more, a smooth surface equivalent to or better than that obtained with a heating trowel can be obtained.

Incidentally, when similar rolling molding was performed using the same shaped trowel and mold by the conventional heating trowel method (gas burner heating), good molding could not be achieved unless the moisture content was maintained at 21±0.5% by weight.

In addition, FIG. 1 also shows other main parts of the rotary rolling potter's wheel molding machine used in the present invention. Rotating iron 3A
is opposite to the mold surface 17A of the mold 17 (which rotates about the potter's wheel rotation shaft 15 while being supported by the mold holder 16) with the molding surface 3C facing downward, with a predetermined interval t (thickness of the molded product), and a rotary shaft. It is fixed to the flange 7 at the lower end of the holder 8 via the holder 2. The central axis 19 of the rotating shaft 8 intersects the potter's wheel rotating shaft 15 at an angle θ, and the intersection point 0 is arranged to approximately coincide with the center of the molding surface 3C.

An air supply port 5 passes through the center of the rotating shaft 8 and communicates with a compressed air source via a rotary joint 9. The lower end of the air supply port 5 opens into the air chamber 4 to distribute air throughout the iron. The rotating shaft 8 is supported via bearings 10 and 11 by a support member (not shown) (which can move up and down). At the beginning of molding, the rotary trowel 3A is gradually moved downward, rolling the clay and discharging excess clay outward, and reaches the position shown in the figure at the end of molding. As a result, the molded product 18 is rolled to have a uniform density and a smooth surface as the clay is subjected to a rolling action by the relative rotation of the mold 17 and the rotary trowel 3A with a predetermined interval t.

[Effects of the Invention] The effects of implementing the present invention are listed below.

1. Temperature adjustment of the trowel, which requires skill, which was required with conventional heating metal trowels, is no longer required, and only a constant supply of gas (particularly air) to the trowel is required.

2. No heating is required with the trowel, which saves energy and improves the working environment.

3. Since there is no adhesion of clay that occurs with heating trowels, softer clay can be used compared to heating trowels, and the load on the potter's wheel rotation device can be reduced.

4. The weight of the iron can be reduced, making it easy to handle.

5. Eliminates molded product defects due to insufficient heating or overheating.

6. The range of water content in the clay can be expanded, and rolling molding can be performed even if the amount of clay as a plasticity imparting component in the clay is smaller than before.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention.

Claims (1)

[Claims] 1. In the potter's wheel rolling method for ceramics, the diameter
Using a rolling trowel with 0.1-0.5 mm ventilation holes,
A potter's wheel rolling method for ceramics characterized by rolling and forming while always forming a thin gas film between the clay and the trowel surface by ejecting gas from the trowel surface. 2. A potter's wheel rolling shaping trowel for ceramic clay, comprising a trowel body equipped with a rolling forming surface having one or more ventilation holes with a diameter of 0.1 to 0.5 mm, and a gas supply means for ejecting gas from the forming surface.