JPS6210588A - Baking device for ceramic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for firing ceramic materials which is particularly useful for firing tiles and especially glazed tiles.

[Conventional technology]

Glazed tiles are tiles that have undergone a firing process at temperatures above 1100°C.

In this case the glazed tiles are fired in a roller furnace heated by a plurality of burners. The tiles are conveyed through the furnace by a plurality of independently rotating rollers.

Although this type of roller furnace has a high production rate, it has the inherent disadvantage of deformation of the tiles during the firing process. A square or rectangular raw tile is transformed by firing to produce a scalene-shaped fired tile.

Scalene tiles cannot be laid - even if their deformation is relatively small, because during installation,
Particularly in the Italian design method, if one tile has a defect, this defect is added to the defects of the next tile.
The disadvantage is that it is very noticeable and the finish is difficult to look at.

It has thus become customary to provide a sorting device at the outlet of the furnace in order to separate acceptably deformed tiles from excessively deformed tiles that should be rejected. Tile manufacturer practice indicates that acceptable tile standards should be no more than 0.4% deviation from a perfectly square or squared standard specimen.

Tile manufacturers seek even smaller deviations in order to obtain a more valuable product anyway, and therefore deviations of less than 0.25% are desired.

Apart from the regularity of the dimensions of the tiles, we will discuss the structure of the furnace channels for processing tiles according to the current state of technology. Guerco dated October 7, 1977
Welko Indu
Italian patent application 28352A/77 filed by Striale S, P, A) discloses a channel-type furnace with a plurality of indirect heating chambers placed successively along a path for ceramic material. According to the application, the connection between each chamber and the next chamber is carried out by a pair of upper and lower transverse walls, in which the nuclide forms the neck of the bottle, which forces the flow of hot gas. Then, it is forced to flow as close as possible to the material to be fixed.

The neck of such a bottle, according to the said patent Kawahara, allows the upper wall to be lowered so as to graze the top of the moving ceramic material.

Can be adjusted to supply ceramic materials of different dimensions.

It has been found that such a transverse wall forming the neck of the bottle allows improved control over the longitudinal distribution of temperature along the furnace. In fact, the neck of the bottle divides the furnace into several continuous chambers, even if the structure is adjacent.
Room temperature can be controlled relatively easily.

However, the coordination arrangement cannot overcome the tile deformation problem mentioned above. The inventors have confirmed that the deformation during firing is not due to the longitudinal temperature distribution along the furnace, but is closely related to the constancy of the temperature distribution in the cross section. The inventor has in fact shown that the temperature deviation in the furnace along the cross-section determines the corresponding deformation in the tile, and that if the temperature in the furnace remains constant within permissible limits along the cross-section within the passage range of the tile. We have found that regular product dimensions can be achieved by simply using this method.

The temperature deviation along the cross section should be smaller than 0.25% (ΔT = 2-3 °C) in the central area of the furnace and 0.5% (ΔT = If it is smaller than 5-6°C), it is within the permissible limit. The term "terminal side" applies to approximately 5 to 10 sub-sections of the cross section adjacent to the wall located within the range of the tile. The aim is to achieve the constancy of the cross-sectional temperature specified above in order to produce tiles with acceptable deviations with respect to the standard, thereby making a complete installation possible. A further object of the present invention is to reduce rejects and to avoid as much as possible the need for the above-described sorting device located at the exit of the furnace.

Another object of the invention is to utilize all the internal space of the channel as a firing area, thus reducing the dimensions of the channel and correspondingly increasing the thermal output.

[Means for solving problems]

The inventors have surprisingly found that the above object is achieved by the following device. an apparatus for firing a ceramic material comprising a channel heated by a plurality of burners and a plurality of rollers arranged on a plane for conveying the ceramic material along the channel; The crown of the channel, at least in the high temperature firing zone, has a plurality of downwardly extending reliefs arranged transversely to the direction of advancement of the ceramic material, the reliefs being separated from each other by a distance of not more than 1 meter. This device is characterized by the following.

It has been specifically found that if the reliefs are separated from each other by a distance ranging from 25 to 75 centimeters, the resulting nine tiles exhibit a particularly reduced deviation from the standard.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, the curve pattern represents the cross-sectional distribution of temperature. If the maximum temperature deviation from the set average in sections 2 to 3 is 2 to 3 degrees Celsius, and in section 1
~2,3~4 or more, maximum temperature deviation from set average is 5
The curve is optimal if it is as small as ~6°C (0.5° below the furnace temperature). Sections 1-2, 3-4 are approximately 5-10
with side length.

In FIGS. 2, 3, and 4, ceramic.

The apparatus for sintering the material consists of a channel 10 heated by a plurality of burners 11 located close to the crown 12 and a plurality of burners 13 located close to the hearth 30.

The device consists of a plurality of rollers 14, which are attached to the tiles 2.
0 is conveyed longitudinally along the channel.

The crown part 12 has a plurality of reliefs 16 according to the invention, which extend transversely to the direction of advancement of the tile.

Each relief extends downwardly from the crown 12 of the channel to the bottom 18 of the relief 16.

This extension is 1/6 of the distance, measured vertically, from the crown 12 to the support plane of the tile 2o on the roller I4.
It is preferable to exceed the IA, and more preferably even to exceed the IA.

If, without considering the burner 13 located below the roller plane, but just the burner 11 located above the roller plane, according to the invention there is at least 2 holes between two adjacent reliefs 160. Two burners 11 are included.

Desirably there are between 3 and 7 burners between two adjacent reliefs 16 and close to the crown 12.

In a preferred embodiment of the invention shown in FIG.
The relief 16 has coupling means, for example a recessed rib 22, suitable for engaging with the support structure of the crown of the channel 1o.

In lieu of the above, and without departing from the scope of the invention, in FIG. 6 the reliefs 4o form one structure with the support beam of the crown portion 12 of the channel and thus themselves form a support beam.

〔effect〕

The device according to the invention has a 0.2
A glazed tile with no deformation exceeding % is obtained,
It has been confirmed that there are practically no rejects, thus ultimately solving both equipment and thermal efficiency problems. The invention can be utilized in practice without leaving any wasted space, allowing the entire surface of the conveying plane defined by the rollers, thereby reducing the transport volume and increasing the output.

[Brief explanation of drawings]

FIG. 1 shows a graph of temperature along the cross-section of the channel in the plane of Row 2. FIG. 2 shows a longitudinal section through the channel. FIG. 3 shows a partially sectional plan view of the channel of FIG. 2; FIG. 4 is a cross-sectional view of the channel along line 1 to 2 in FIG. 2. FIG. 5 is a perspective view in elevation according to the invention. FIG. 6 is a cross-sectional view through a channel according to another embodiment. 10... Channel, 12... Crown part, 1
1.13-... Burner, 14... Low 2.1
6.40... Nireleaf, 20... Tile, 2
2...dent reply, 30...hearth - Figure 1 Figure 6 Figure 3

Claims (1)

[Claims] 1. A channel heated by a plurality of burners;
An apparatus for firing ceramic material comprising a plurality of rollers arranged in a plane for conveying the ceramic material along said channel, wherein the crown of said channel is configured to convey the ceramic material at least in the high temperature firing zone. A device characterized in that it has a plurality of reliefs arranged across a downwardly extending relief arranged transversely to the direction of advancement, said reliefs being separated from each other by a distance of not more than 1 meter. 2. The device of claim 1, wherein the reliefs are separated by a distance of 25 to 75 centimeters. 3 Each said relief is 1/6 of the distance from said crown to the current plane of the ceramic material on said roller.
3. A device as claimed in claim 1 or claim 2, extending downwardly from the crown of the channel by a distance greater than . 4 Each said relief is 1/4 of the distance from said crown to the current plane of the ceramic material on said roller.
4. The device of claim 3, wherein the device extends downwardly from the crown of the channel by a distance greater than . 5. Claims 1 to 4 comprising at least two burners arranged in the plane of the roller close to the crown in a channel section between two successive reliefs. The device described in any of the above. 6. The burner according to claim 5, comprising between 3 and 7 burners arranged in the channel section between two successive reliefs and in the plane of the roller close to the crown part. Device. 7. A device according to any one of claims 1 to 6, wherein each relief has coupling means suitable for engaging the support structure of the channel crown. 8. A device according to any of claims 1 to 6, wherein each relief forms a support beam that bears the loads of the channel crown.