SI8711360A8 - Device for applying enamel in granulated form onto ceramic plates on high temperature - Google Patents

Description

APPLICATION APPARENT AS VIEWS GRANULES ON CERAMIC TILES

THAT ARE HELD AT HIGH TEMPERATURE

FIELD OF THE INVENTION

The invention falls within the field of apparatus for the application of liquids or other flowable materials to surfaces. Designation according to the International Classification of Inventions: B 05 C 5/00 and 22/00.

Technical problem

The invention solves the problem of how to construct the coating device in the form of granules on ceramic tiles at a high temperature, at which the dispenser will be sufficiently separated from the tiles to avoid its heating, and which will provide such distribution of granules to look to obtain a uniform layer of viewing. all over the surface of the tile, including its edges.

Stahje techniques

Processes for the production of ceramic tiles are known which allow the granules to be applied to the tiles as they are baked during heat treatment, which means when the tiles are at high temperature.

One process of this kind is the subject of an Italian patent application which is under examination by the public.

Applying a granular look to hot ceramic tiles causes many technological, physical and chemical problems.

The fact that the temperature of the tile is much higher than the melting temperature of at least some of the components is considered in the process.

The tile-facing dispenser is exposed to heat due to heat transmitted from the tiled tiles, either by radiation or by convection.

It can be assumed that this difficulty can be overcome by moving the view dispenser away from the tiles, thereby reducing the amount of heat exerted by the tiles.

The Applicant found that the increased fall height of the granule view, which occurred in this way, had serious disadvantages.

Namely, if the height of the fall is too large, the view is selectively exposed to the rising currents of air that occur in the presence of colorful tiles located in the middle with a lower temperature. It is clear that small-sized particles are more likely to be retarded by these rising air currents, leading to some sort of separation between granules of different sizes.

In addition, when the branching granules fall from a height, they acquire too much kinetic energy that seems to bounce off the surface of the tiles, and as a result of ascending air currents, the separation of small, tiny fractions during the fall can cause uneven application due to the falling particles. look is not perfectly constant and uniform.

moreover, the fact that the granules that fall too fast tend to bounce off the tiles makes it uneven to apply to the surface of the tile, especially along the edges, especially at the front, or leading edge.

It follows that all these facts make it necessary for the height of the falling particle to be as small as possible.

The spontaneous heating of the dispenser placed next to the glowing tiles is therefore unacceptable, since as the temperature approaches the temperature of the tiles, the more components look at the lower the melting point begins to melt, which will cause them to crumble in the dispenser and in practice prevent proper propagation is looking.

Qpi§ regime tries to solve the problem by realizing a single dispenser that applies a view from falling from a low height to the incandescent tiles, that is, to the tiles.? At ~ temperatures higher than the melting point of the viewing.

This solution is based on the observation that, of course, the amount of heat transmitted by the glowing tile to the dispenser is the radiant heat.

It is known that heat exchange by radiation is proportional to the fourth degree spillage of the body temperature between which this heat transfer takes place.

It has been experimentally shown that cold gaze falling on the tile surface drastically reduces radiation.

This is because the outer surface of the tile starts to consist of the watch itself, which absorbs heat from the surface layer of the tile, so that the temperature of the watch (taking into account the specific heat of the watch and the melting temperature of its soluble components) obviously comes with a corresponding decrease in the temperature of the surface layer the small heat transfer coefficient of ceramic bodies such as the support or the substrate of a single ceramic tile should be taken into account.

In this way, according to the invention, the view is poured in the form of a cascade or curtain from at least one free edge of a cold hair of the surface on which the view can slide in the form of granules that are brought to it.

The gaze is brought to that hair, the sloping surface and, when it falls on it, it loses kinetic energy, if it had one.

It is advantageous that the free edge from which the tile falls on the tile be positioned near the outer surface of the dispenser, so directed that it lies in the trajectory of approaching the tile to the dispenser, so that the tiles extend below the dispenser body after receiving at least a portion of the granule view.

In particular, the dispenser comprises multiple edges from which the view falls, which are transversely positioned in the direction of movement of the tiles.

The characteristics of the invention will be clearer from the examination of descriptive embodiments of the same, with reference to the accompanying drawings, where: - figure 1 shows a simplified view of one preferred embodiment of the device according to the invention, '- figures 2 and 3 show the side and horizontal projection of the device of figure 1;

4 and 5 show partial projections similar to those in FIG. 2 for different embodiments of the invention.

In Figures 1 to 3, the furnace 10 is simplified showing the zone 11 in which the dispenser according to the invention is formed, as a whole, denoted by 12.

Oven 11 is a conveyor with a conveyor roller, conventional in itself, and is therefore not described in more detail. No. 13 is a schematic diagram of the drive rollers that transfer the plates 14 to the furnace where they are subjected to a judo j heat treatment, which is explained in detail in Italian patent application no.

19589 A / 85 by the same applicant.

The dispenser 12 is provided with tile transfer rollers 20, which represent an extension of the row of rollers 13 from the pedi.

The devices used to drive the rollers are not shown in greater detail, and may be mechanisms with chains or gears, which is common with this type of equipment.

Preferably, and so shown in the drawings, the rollers 20 have a dashed surface so that the plate is supported so that it rests on individual points.

This discontinuity can be achieved by rolling the roller 20 with the central tubular portion 21 with annular reinforcements 22, whereby coolant, most preferably water, is passed through the tubular portion 21, most preferably water, which is supplied and drained from both ends through tubes 23 and rotary joints. or terminals 24 (Figure 3).

This shape of the rollers 20 has proved to be useful in preventing their thermal deformation in the event of stopping and restarting of the rollers for transferring the glowing plates.

For when the incandescent plates coming from the pedi on said rollers 20 come into contact with the rollers which, if interrupted by movement, are suddenly cooled, whereby the tiles touch the rollers in approximately one of their longitudinal regions, the rollers tend to deform and to form a bulge near the highest temperature derivative.

This deformation, which is the result of thermal imbalance, does not tend to self-compensate, and even tends to increase in the first few minutes of operation, and then gradually decrease.

In fact, when the rollers bend to transfer the tiles, the hottest bulging portion of the rollers comes in contact with the tiles, and this tends to maintain a thermal imbalance between different roller regions.

If the rollers are designed to have interrupted support surfaces, the occurrence and duration of this thermal imbalance is prevented, and the amount of heat released from the tiles is also limited, allowing the rollers to cool without reducing the tile temperature to any greater extent. . It has been shown to be particularly advantageous to maintain the thermal equilibrium of the rollers on an outer surface consisting of annular ribs, which also perform the function of distributing heat by the circumference of the rollers.

The view dispenser includes a granule 25 for receiving views in the form of granules, the lower end of which is provided with a feed mechanism consisting of, for example, a rotating pulley 26 which prevents the formation of clumps in mass and brings the view to the oscillatory sieve 27.

From this screen, the view in the form of a granule falls on a group of rollers 30 mounted directly above the surface of the tiles mounted on the rollers 20.

And these rotating rollers 30 have cooling in the form of fluid passing through them in a manner exactly identical to that for cooling the rollers 20.

It should be noted that one watches when falling on a turn ^1? the roller 30 is slowed down so that its kinetic energy is reduced by the impact. '

This means that the height of the supply elements is not very critical, so they can be placed at a suitable distance from the tiles so that they are not subjected to dangerous overheating, without forgetting that the minimum mpg output must be minimized when falling and irregular deposition. fine factions watch.

? Consideration should also be given to the fact that the rotating rollers 30 represent a shield against the radiation heat coming from the tiles.

Near the rotary distributor rollers 30 and below the rollers 20, a hopper 33 is arranged to collect all those views passing through a row of adjacent tiles adjacent to the view dispenser. . i

This funnel should be designed to reduce the appearance of the chimney effect due to the presence of incandescent tiles, and to this end, it is advantageous for the funnel to have transverse bulkheads 34 and that the outlet opening for the collected view is hermetically connected to the viewing device.

This design of the dispenser has proved to be capable of satisfactorily achieving the objectives of the present invention.

Each of the rollers 30 contains in its upwardly directed portion an inclined double surface from which the view falls in the form of a cascade or curtain on the tiles, or more precisely from the edges formed by the roller derivatives tangent to the vertical planes.

Choosing a roller 30 is not critical as regards the spreading of the watch, which they can do even when they are not moving.

However, rotation is extremely useful for continually changing a portion of the roller surface exposed to the radiant tbplot of the radiant tiles, thus making the rollers easier to cool, and said rotation also ensures that no roller portion reaches the initiating temperature the component melts on the watch, as well as different spreads that may deform the rollers 30.

According to the invention, the first of the rollers 30 which has tiles moving on the rollers 20 (from left to right, according to Figure 1j is arranged so that it imparts a view, by means of one of its edges, by tiles before they enter the area below itself dispensers,

As explained earlier, the first drop in vision results in a drastic decrease in the radiation from the tiles, as a result of the lowering of the temperature of their surface layer, although this does not cool the masses within them to the extent that could cause some more noticeable thermal imbalance and internal voltages that would lead to cracks in the product.

In this way, the roller assembly 30 is subjected to drastically less radiation than would be the case if the plates that flow beneath it were not cooled by falling on them.

In addition, the rollers 30 form a shield that protects the upper parts of the dispenser from both radiation and convection.

The existence of more than one roller 30 (and not just one) allows the surface of the tiles separated from them to be enlarged, albeit while maintaining a relatively small diameter of the rollers, thereby limiting the height of the falling sight in accordance with the object of the present invention.

It has been found advantageous to distribute the view so that it falls with several successive edges, which also improves the distribution of weeping.

The gaze falling from the first edge of the dispenser onto the glowing tile immediately begins to appear softening and melting, resulting in the gaze falling from the edges when it reaches its path onto the tile has less tendency to bounce off the tile.

The tiles taken out of the ovens on the rollers 13 and then conveyed by the rollers 20 must have a certain longitudinal and transverse distance between them. In the case of rollers, rollers 30 are thrown in a part according to these distances between the tiles more expensive in the lower funnel or collector 33 and can be returned to the dispenser if desired.

The reservoir 33 has baffles 34 that form a view maze, divert upward air currents outside the viewing area itself, and can be cooled appropriately to compensate for the heat applied to the underside of the tiles.

Because they are cooled and because of their small contact area with the plates, the rollers 20 can be maintained at a temperature substantially lower than the melting temperature of the component with?. Looks at the lowest melting point, preventing it from adhering to the surface of the rollers.

As stated earlier, the configuration of the inclined surface in the form of a roller, for pouring in the form of a cascade or curtain looking at the tiles, has proved to be extremely advantageous for a number of reasons stated above.

These rollers can, however, be replaced by surfaces 40 with edges 41 from which they face the tiles.

It is desirable that the surfaces 40 are made with a cavity 42 in which some coolant is forced to circulate, as with rollers 30.

Surfaces 40 need not be static. However, in the interest of satisfactory distributions and free movement of the views, they may be constructed as vibrating elements, for example attached to a sieve 27.

For surfaces 40, more than one is advantageous, in order to achieve a gradual and even distribution of views over the tiles as well as the evenness of the layer.

Figure 5 shows that the first surface 40 is inclined towards the side where the tiles come from, so that the tiles come under the dispenser already covered with view, in accordance with all that has been said before.

Other surfaces 40 ^{# are} shown, however, to be turned to the other side, since it has been shown to be more suitable with respect to the more uniform overlapping of the front and sides for the viewing granules to have one horizontal component of the falling path, parallel to the movement of the plates in the same direction.

Claims (5)

(13? With precision what is it J r ed a j application looks at ceramic tiles that. maintaining a dispenser (12) above the tile roller system for viewing, at a tile above the rotating hollow rollers (30) for dispensing, through which coolant flows, a dosing cylinder (26), and a vibrating sieve (27) was installed between the cylinder (26 'for dosing and the hollow rollers (30) for application. 2. The device according to claim 1 and variant 1, characterized by a rail, which has multiple parallel surfaces (40) arranged on the dispenser (12) for distribution of views, with end edges; cavities (42) for circulating coolant. incline h (41) i 3, Device according to claim 2 and variant II, characterized in that the surfaces (40 ') are inclined opposite to the direction of movement Device according to claim 1, characterized in that there is a coolant fluid through each of the hollow shafts (21). wave strong SE -i «E! Multiple coaxial ring calves set up for tile transfer Apparatus according to claim 1, characterized in that a collector (33) for collecting the granules of the cross-sectional view of the edges of the plates, with barriers (34) for cross-views, is mounted below the roller conveyor system (20).