EP1507748A2

EP1507748A2 - An apparatus and a process for production of decorated ceramic tiles

Info

Publication number: EP1507748A2
Application number: EP03720857A
Authority: EP
Inventors: Alberto Franceschini
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-05-24
Filing date: 2003-04-02
Publication date: 2005-02-23
Also published as: AU2003224431A1; WO2003099737A2; ITMO20020142A0; WO2003099737A3; ITMO20020142A1; AU2003224431A8

Abstract

The apparatus of the invention produces ceramic tiles having decorative effects similar to those of natural stone, and comprises a device with a perforated rotary belt interpositioned between a hopper (12) which loads and dispenses various powder materials and a conveyor belt (11) on which the materials are deposited and distributed in various compositions and mixes to be deposited in tile-forming dies.

Description

Description An Apparatus and a Process for Production of Decorated Ceramic Tiles.

Technical Field

The invention concerns an apparatus and a process for production of ceramic tiles. In particular, the invention relates to an apparatus and a process for obtaining a suitable mixing of the materials used in the production of ceramic tiles, where the tiles have decorative effects throughout their entire height, or for a relevant part thereof. Background Art

In the prior art, the production of ceramic tiles for floors and coverings usually includes a loading stage of a mixture of powdery materials into forming dies, at least a stage of pressing the mixture of materials, and at least a stage of suitably controlled firing of the pressed products.

The invention provides a new process and apparatus for loading the powder materials, thanks to which special and characteristic decorative effects can be obtained, making the finished tile look similar to natural stone. An advantage of the invention is that the apparatus is constructively simple and economical.

These and other aims and advantages are attained by the invention, as it is characterised in the appended claims.

In a preferred embodiment of the invention, the apparatus comprises a rotary perforated belt exhibiting variously-shaped elements on the belt which partially occlude the perforated surface of the belt. The rotary belt is interposed between a hopper dispensing the various powder materials used in manufacturing ceramic tiles, and a conveyor belt which is translatable from a first position, in which the materials dispensed from the hopper are loaded onto the conveyor belt and passed thereon by means of the perforated belt, and a second position in which the powder materials are progressively deposited into the tile-forming dies. During the powder material loading stage onto the conveyor belt, the rotary perforated belt is maintained at a constant distance from the conveyor belt (this distance can vary according to the crushability of the deformable material the occluding elements are made of). Once a determined amount of material has been loaded, the perforated belt and the hopper are distanced from the conveyor belt, which is then translated towards the position for depositing the materials in the forming die. After the powder material deposited in a layer on the conveyor belt has been freed from the perforated belt and its occlusion elements, the powders spontaneously mix on the conveyor belt due to the force of gravity. This mixing occurs especially at the edges of the various groups of materials contiguously deposited in arrangements given by the shape and distribution of the occlusion elements. The above-mentioned powder materials, thus mixed, are progressively deposited in the tile-forming dies, producing innovative decorative effects throughout their breadth. Disclosure of Invention Further characteristics and advantages of the present invention will better emerge from the detailed description that follows of a preferred but non-exclusive embodiment of the invention, illustrated purely by way of a non-limiting example in the accompanying figures of the drawings, in which: figure 1 is a schematic view of an apparatus according to the invention; figure 2 is an enlarged view in partial section, according to line II-II of the apparatus of figure 1 ; figure 3 is a detailed view, according to line III-III, of the apparatus of figure 1 ; figure 4 is a detailed view similar to that of figure 3, but referring to a different configuration of the apparatus of the invention.

With reference to figure 1 of the drawings, 10 schematically denotes an apparatus used for the production of tiles and, in particular, for the preparation of materials used in the manufacture of the tiles themselves.

The apparatus 10 comprises a conveyor belt 11 which, apart from the usual rotation motion typical of a ring-wound continuous conveyor belt, can also translate horizontally in known ways from a first position, corresponding to the configuration illustrated in the figure, to a second position located at the tile- forming dies.

The apparatus 10 further comprises a hopper 12 into which (for example by one or more tubes 13 as in the illustrated example, or by a conveyor belt or other known loading systems) various powder or granular materials are loaded, used in the manufacture of ceramic tiles. In the illustrated embodiment each tube 13 is connected to a respective infeed piping for a particular type of material, which is automatically and gradually loaded into the hopper 12, in known ways, as it empties.

Inside the hopper 12, successive layers of different materials (by colour and type) are created, each of which is separately infed continuously by means of the above-mentioned infeed pipe. The hopper 12 is also inferiorly provided with a discharge mouth with controlled opening.

Another system, not illustrated, for the loading of the hopper 12 can comprise one or more powder-infeed tubes of various colours, which load the material into a horizontally-translating drawer which supplies the hopper from above. A further group included in the apparatus 10 is a rotary belt 14, perforated so as to be extremely permeable for fluidity of powder material transfer. The rotary belt 14 is ring-wound and in the illustrated embodiment is triangular, but could be trapezoid or of another shape.

The lower side 15 of the perforated rotary belt 14 is interpositioned between the conveyor belt 11 and the hopper 12.

The perforated rotary belt 14 is made up of support net 16, with sufficiently large holes to enable fluid and obstacle-free passage of the powder or granular materials coming from the hopper 12.

The net 16 is stretched between two lateral frames 17 and 18 made of a flexible material, and is rotated about rollers 19 arranged at the angles of a triangle (or a trapeze). The hopper 12 is located internally of the corners of the triangle. Figure 2 shows that elements 20 are applied to the net 16, which elements 20 are made of an elastically deformable and preferably soft material (for example, made of rubber or foam rubber, or sponge or another like material). The elements are variously shaped and distributed over the surface of the perforated rotary belt 14 , creating occluded zones on the belt 14 where the powder or granular material cannot pass through the net 16 of the belt 14. The parts of the belt 14 left free of the elements 20 constitute shaped openings for the free passage of the loose ceramic material distributed by the hopper 12. The net 16 essentially has the function of supporting the elements 20 which create the occlusion zones. The height of each of the elements 20 is about the same as the breadth.of the layer of ceramic powder which will be distributed on the conveyor belt 11 and which is destined to fill the forming cell of the die.

The powder distribution group, i.e. the group comprising the hopper 12 and the perforated rotary belt 14, can on command move vertically, nearing and distancing from the conveyor belt 11. The ceramic material distributed in layer form by the hopper onto the conveyor belt 11 passes through the perforated rotary belt 14. During this stage (see figure 3) the breadth of the elements 20 is more or less equal to the distance between the bottom side 15 of the perforated rotary belt 14 and the upper surface of the conveyor belt 11, so that the material passing through the net 16 (but not passing through the occlusion elements 20) accumulates on the conveyor belt 11 in distinct mounds, as illustrated in figure 3. The occlusion elements 20 and the conveyor belt 11 , which are in contact with each other, define the spaces which are filled by material exiting from the hopper 12; the spaces are inferiorly delimited by the belt 11, superiorly delimited by the net 16, and laterally delimited by the deformable occlusion elements 20. The distribution of the layers of the various materials in the above-mentioned distinct mounds is extremely variable. It is a function of the shape and distribution of the occlusion elements 20, which give rise to partial and continuously variable occlusions of the hopper discharge mouth, producing inside the hopper itself a varied distribution of the layers of the various materials. When the above-mentioned mounds of materials, following the relative movement of the conveyor belt 11 with respect to the hopper 12, occupy a predetermined tract of the conveyor belt 11 , such as for example the tract illustrated in figure 1, the discharge mouth of the hopper 12 is closed and the hopper and the perforated rotary belt 14 are distanced from the conveyor belt 11, in the direction of arrow F of figure 4. The conveyor belt 11 is then translated towards the filling station of the tile-forming dies.

In this situation, the various mounds of loose material arranged on the conveyor belt 11 separately, as shown in figure 3, are distributed over the surface of the conveyor belt 11, in the process mixing together, especially in the spaces previously occupied by the elements 20, and generating in those zones "veins" of colours of various shapes and sizes. This is in effect a directed mixing of the materials deposited on the conveyor belt 11 , which takes place in determined areas of the conveyor belt 11 corresponding to the areas occupied by the variously-conformed occlusion elements 20 applied on the perforated rotary belt 14.

The various materials thus mixed are then progressively deposited in the dies, thanks to the movement of the conveyor belt 11 in a same advancement direction or in an opposite direction.

The apparatus of the present invention operates according to the above-described process. A production method for ceramic tiles with special decorative effects, enacted by the above apparatus consists in the following:

- loading various materials used in the manufacture of ceramic tiles into a hopper with a controlled outlet mouth, the loading being performed by means of separate piping for each type of the materials;

- removing a predetermined quantity of the materials from the hopper and contemporaneously depositing them on a conveyor belt underlying the hopper, the removal of the materials being done in a non-uniform manner by varying the aperture of the outlet mouth of the hopper and causing a perforated rotary belt 14 to run between the outlet mouth of the hopper 12 and the conveyor belt 11; the perforated rotary belt 14 exhibiting variously-shaped occlusion elements 20;

- generating a directed mixture of the materials deposited on the conveyor belt 11 , the mixture preferably being created in determined areas of the conveyor belt 11 , the determined areas corresponding to the areas occupied by the occlusion elements 20 applied on the perforated rotary belt 14;

- progressively depositing the mixed materials in ceramic tile-forming dies;

- proceeding to successive traditional-type pressing in the dies, and/or firing;

- performing any necessary sanding operations on the tiles after pressing and/or firing.

In more detail, the operation in which the powders are deposited on the conveyor belt 11 can include the following stages: a) positioning in reciprocal contact the perforated rotary belt 14 and the conveyor belt 11; b) opening the lower outlet mouth of the hopper 12; c) rotating the conveyor belt 11 and the perforated rotary belt 14 at a same speed so that the powders pass through the holes in the perforated rotary belt 14 at the zones thereof not occupied by the occlusion elements 20; d) once the necessary quantities of powders are distributed, the hopper 12 closes; e) the conveyor belt 11 and the perforated rotary belt 14 continue to move at the same speed until the layer of powders deposited on the conveyor belt 11 has exited from the perforated rotary belt 14; f) the loading group (perforated rotary belt 14 and hopper 12) is raised to detach the perforated rotary belt 14 from the conveyor belt 11 ; g) the conveyor belt 11 deposits the layer of powders into the forming cell of the die. A further depositing of powders can be performed (for example using a normal hopper), above the irregular layer of powders formed by the perforated rotary belt 14 with the occlusion elements 20, with the aim of filling the parts left uncovered by the first layer, i.e. the zones of the conveyor belt 11 with less powder or indeed without powder. Alternatively, in stage e) above the conveyor belt 11 and the perforated rotary belt 14 can continue moving at the same speed until all the material has passed through the net 16 and is imprisoned in the spaces defined laterally by the deformable occlusion elements 20. In this case the layer of powders deposited on the conveyor belt 11 exits the perforated rotary belt 14 in the successive stage f) when the perforated rotary belt 14 is raised; obviously the horizontal tract of the lower branch of the perforated rotary belt 14 comprised between the outlet of the hopper 12 and the front roller 19 must be sufficiently long to house the quantity of powder needed for loading the die.

The advantages connected with the innovative and effective mixing action of the materials composing the ceramic tiles obtained using the apparatus of the inventino are obvious from the above description, and it is also evident that the characteristics can be subject to some modifications and variants without losing their original qualities.

The overall conformation of the perforated rotary belt 14 could for example be varied, both in internal dimensions and overall shape, and might be other than triangular or trapezoid, though these are considered the most advantageous shapes in terms of simplicity and costs of realization.

The structure of the net 16 might also be varied, as, obviously, can be the occlusion elements 20 applied thereon.

The material of the elements 20 can certainly be changed, though synthetic rubber and latex remain the most industrially viable materials. The invention can be used for tiles with all-through decorations, or for tiles with decorations penetrating partially through the whole height; in the latter case the

"double loading" technique can be used.

Claims

Claims.

l).An apparatus for production of decorated ceramic tiles for floors and coverings, comprising a device for dispensing powder materials used in manufacturing ceramic tiles, provided with a controlled opening for depositing at least one layer of the powder materials on an underlying horizontally-mobile conveyor belt (11), by means of which conveyor belt (11) the powder material is transferred to tile-forming dies, wherein the apparatus comprises a perforated rotary belt (14), permeable for the powder material, predisposed between the dispensing device and the conveyor belt (11), the perforated rotary belt (14) bearing variously-shaped occlusion elements (20) of a uniform thickness for partially obstructing the outlet of the dispensing device for preventing passage of the powder material through the perforated rotary belt (14) only in predetermined zones thereof.

2). The apparatus of claim 1, wherein the occlusion elements (20) are made of an elastically-deformable material. 3). The apparatus of claim 1 or 2, wherein the perforated rotary belt (14) is vertically mobile, being able to distance from and near the underlying conveyor belt (11).

4). The apparatus of any one of the preceding claims, wherein the perforated rotary belt (14) is ring- wound in an overall triangular or trapeze shape and is rotated about rollers (19) arranged at angles of the triangular or trapeze shape; a bottom tract (15) of the perforated rotary belt (14) being interposed between the outlet of the dispensing device and the conveyor belt (11). 5). The apparatus of any one of the preceding claims, wherein the perforated rotary belt (14) comprises a support ^'net (16) which has sufficiently large holes to enable fluid passage of the powder materials coming from the outlet of the dispensing device; occlusion elements (20) of various shapes being applied on the net (16).

6). The apparatus of any one of the preceding claims, wherein a height of each of the occlusion elements (20) is about equal to a thickness of the layer of powders to be deposited on the conveyor belt (11). 7). The apparatus of any one of the preceding claims, wherein the conveyor belt

(11) is translatable from a first position, in which the powder materials dispensed from the dispensing device are loaded on the conveyor belt (11), to a second position, in which the powder materials deposited on the conveyor belt (11) are progressively deposited in tile-forming dies.

8). A process for producing decorated ceramic tiles, comprising the following stages: loading various powder materials used in the manufacture of ceramic tiles into a hopper (12) with a controlled outlet mouth; removing a predetermined quantity of the powder materials from the hopper (12) and depositing them on a conveyor belt underlying the hopper to form a layer of the powder material, the removing being done in a non-uniform manner, causing a perforated rotary belt (14) to run between the outlet mouth of the hopper (12) and the conveyor belt (11); the perforated rotary belt (14) exhibiting variously- shaped occlusion elements (20), which obstruct the outlet mouth of the hopper

(12) in order partially to prevent a passage of the powder material through the perforated rotary belt (14);

- progressively depositing the layer of powder materials in ceramic tile-forming dies;

- proceeding to successive pressing operations in the dies, and to firing of the tiles. 9). The process of claim 8, wherein, during a stage of depositing the powder material on the conveyor belt (11), the perforated rotary belt (14) and the conveyor belt (11) run in contact with one another and at a same speed. 10). The process of claim 8 or 9, wherein, during the stage of depositing the powder material on the conveyor belt (11), cavities remain between the perforated rotary belt (14), the conveyor belt (11) and the occlusion elements (20), which cavities are of a thickness which is about equal to a thickness of the layer of powder materials which are to be deposited, which cavities are filled with the powder material exiting from the hopper (12).