JPH0580322B2 - - 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 to 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 between them to prevent the clay from adhering to the trowel and to maintain smooth contact between the trowel and the trowel.
6281). In other words, in the conventional rotary iron rolling forming method, a rotating iron (roller) is machined from an iron or aluminum material and heated to a high temperature (approximately 100 degrees Celsius) with a gas burner or electric heater. Rolling is performed while creating a film of steam between the sheets.

[Problems to be solved by the invention] In the conventional method, the surface temperature of the solder metal is usually 95°C to 105°C.
A value within this range is appropriate; if it is lower than this, clay will adhere to the iron, 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 the work of constantly maintaining the constant temperature requires skill and has the disadvantage that the work environment is poor due to heat radiation. Furthermore, when the iron is kept in a high-temperature heated state, heat is transferred to the attachment member (for example, a lever or rod) of the iron,
As each mounting member is heated, the effect of thermal expansion appears, which disturbs the position between the mold and the iron.
Furthermore, an error will occur in the rotation axis 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), there are drawbacks such as cracking and adhesion problems, making stable molding impossible. It is difficult to say that this rolling forming method is universal.

The purpose of this invention is to solve the problems of the conventional method.

[Means for Solving the Problems] That is, the present invention firstly uses a rolling molding trowel equipped with a ventilation hole with a diameter of more than 0.5 mm in a potter's wheel rolling molding method for ceramics, and prevents ejection from the surface of the trowel. To provide a potter's wheel rolling molding method for ceramics, characterized in that the pressure is reduced in the latter half of the molding operation to blow out gas and roll molding is performed while always forming a thin gas film between the clay and the trowel. Second, the present invention provides a method for rolling ceramic clay comprising a rolling molding surface having one or more ventilation holes with a diameter of more than 0.5 mm, and a gas supply means for ejecting gas from the molding surface. Provides molding trowels.

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 potter's wheel rolling method for ceramics, and forms a thin gas film by supplying gas (such as compressed air) to the surface of the trowel that comes into contact with the clay. To prevent clay from adhering to the trowel, and to obtain an effect similar to or greater than the effect of preventing clay from adhering to the trowel by generating a water vapor film from the clay using an ordinary heated metal 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 the invention can also be applied to rolling molding of other ceramic green molded objects including whiteware.

[Preferred Embodiment] A specific configuration will be described below. First, use plaster, plastic metal, ceramic material, or a composite or laminated material of these materials to form a molded surface with a diameter of 0.5 mm.
A trowel having at least one through hole, preferably one to several, is produced. The vent hole is preferably formed inside the yarn bottom including the yarn bottom so that dry gas can be blown out through the chamber on the back side of the trowel face. In the potter's wheel rolling forming method, the above-mentioned trowel is installed, and the pressure ejected from the vent hole of the trowel is reduced in the latter half of the forming operation, preferably in the early stage of rolling (the clay covers the front surface of the mold and the clay discharged is relatively high pressure (1Kg)
f/cm ² or more, preferably 1 to 3 Kgf/cm ² ), and relatively low pressure (less than 1 Kgf/cm 2 , preferably less than 1 Kgf/cm ² ) in the later stage of rolling (while the descending of the trowel stops and excess clay is discharged). Molding is performed at room temperature while blowing out gas at a pressure of 0.1 to 1 Kgf/cm ² ). Incidentally, it is sufficient to reduce the gas pressure in stages, but it can also be reduced gradually. At this time, it is estimated that the clay changes from a pressurized state to a substantially atmospheric pressure state at the end of the rolling process. The conditions to satisfy normal temperature molding are 2 kgf/cm 2 in the early stage of molding and 0.5 kgf/cm ² in the latter stage of molding when two 1 mm diameter ventilation holes are symmetrically bored in a 101/2'' dinner plate.
^cm2 . Normally, when using a heating trowel, it is not possible to prevent soil from adhering to the trowel surface unless the clay has a moisture content of 20 to 22wt%, whereas when molding is performed under the above conditions using the trowel of the present invention, the moisture content is 25wt%. Even clay can be molded without any problems, and the molding surface of the clay in the area corresponding to the ventilation holes has a beautiful skin without any traces of ventilation holes.

The cross section of the ventilation hole does not necessarily have to be perfectly circular. In addition, if the diameter of the ventilation hole is set to 0.5 mm or less,
It is necessary to supply gas at a relatively high pressure in order to prevent hole clogging and to distribute a sufficient gas flow rate to form a gas film.If the gas continues to be ejected at high pressure, it will appear as if it were a crater at the position corresponding to the hole in the molded product. Special care must be taken to prevent such traces from occurring, but this problem can be avoided in vent holes larger than 0.5 mm by controlling the pressure periodically as described above. Additionally, drilling pores of 0.5 mm or less requires skill and increases the production cost of the trowel. On the other hand, the hole diameter is 2.0mm
If it exceeds 2.0 mm, it will be relatively difficult to prevent traces caused by the ventilation hole, so it is preferable to keep it to 2.0 mm or less.

The ejected gas may be any gas that is inert under the molding conditions, and usually air (preferably dry air) is used. Further, 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 a trowel material having sufficient strength such as sintered metal, the holder 2 is not necessarily required and can be directly fixed to the rotating shaft (usually its end flange).

Furthermore, with a plastic trowel, a difference of 50 to 100 rpm is required between the rotation speeds of the trowel and the potter's wheel, but in the present invention, molding can be performed without forcibly rotating the trowel. That is, free or driven rotation 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 Three ventilation holes having a diameter of 2 mm were provided at equal intervals, passing through a rotary iron 3A made of a dense metal material and reaching the iron surface 3C. Next, a chamber 4 was provided on the back side of the trowel face 3C so that dry air could be supplied in a range of 0.5 to 5 kgf/cm ² (FIG. 1).

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), 1.5Kg in the first stage of rolling
The molding operation was carried out while blowing out dry air at a rate of 0.5 Kgf/cm ² and 0.5 Kgf/cm ² in the latter stage of rolling. As a result, we obtained molded products of superior quality compared to conventional heating irons, and exhibited 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, if similar rolling molding is performed using the same shaped trowel and mold by the conventional heating trowel method (95-105°C: gas burner heating), good molding will occur if the moisture content is not maintained at 21 ± 0.5% by weight. I couldn't do it.

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 around 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. 8 is fixed to the flange 7 via the holder 2 at the lower end thereof. The center axis 19 of the rotating shaft 8 intersects with the potter's wheel rotating shaft 15 at an angle θ, and the intersection O 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). In the early stage of molding, the rotary trowel 3A is gradually lowered to remove excess clay while rolling the clay, and the state shown in the figure is reached in the late stage 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 moisture content in the clay can be expanded, and the clay can be rolled and formed even if the amount of clay in the clay is smaller than before.

[Brief explanation of drawings]

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

Claims (1)

[Claims] 1 Diameter in potter's wheel rolling method for ceramics
Using a rolling trowel with ventilation holes over 0.5 mm,
A ceramic product characterized in that the gas is ejected by reducing the ejection pressure from the trowel surface in the latter half of the forming operation, and rolling forming is performed while always forming a thin gas film between the clay and the trowel surface. Potter's wheel rolling method. 2. A rotary rolling forming trowel for ceramic clay, comprising a trowel body equipped with a rolling forming surface having one or more ventilation holes exceeding 0.5 mm in diameter, and a gas supply means for ejecting gas from the forming surface.