CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102019000011025 filed on 05/07/2019, the entire disclosure of which is incorporated herein by reference .

TECHNICAL FIELD

The present invention relates to a method and apparatus for the production of ceramic products, in particular for the production of ceramic products with internal streaks or veins .

BACKGROUND OF THE INVENTION

The ceramic industry often aims to obtain ceramic products, such as slabs (e.g. tiles), designed to reproduce as faithfully as possible the typical patterns of natural stone, such as marble and/or granite, or the typical patterns of wood. The slabs of these materials generally have streaks or veins that extend irregularly on the surface and inside the slab. These veins are generally characterised by a colour in (strong) contrast with the background colour of the slab and have jagged edges.

Typically, ceramic products of the type described above are manufactured using plants that comprise devices for feeding different types of ceramic powders to apparatuses for pressing said ceramic powders.

More in detail, plants of the known type comprise a conveyor assembly to transfer the powder material in a substantially continuous manner from an input station to a pressing assembly and, subsequently, to transfer the layer of compacted powder out of the pressing assembly to further processing stations. In such plants, a feeding assembly is placed upstream of the pressing assembly at the input station and comprises a number of ceramic powder dosing devices with different characteristics and/or colours from each other for the creation of a continuous strip of powder on the conveyor belt. The feeding assembly is made in such a way as to create a powder mixture with chromatic effects for the entire thickness that reproduce the patterns of natural stone or wood and are visible both on the surface and on the edges of finished ceramic products. An example of a ceramic powder compacting machine is described in the international patent application with publication number W02005/068146 by the same applicant as this application. However, these plants have the drawback that the distribution of ceramic powder is random, and the choice of the relevant image to be reproduced on the layer of compacted ceramic powder in the slabs is also random. There is therefore a lack of synchronization between internal colour effects and the digital surface printing. This lack of synchronization significantly detracts from the aesthetics of the ceramic product, making a noticeable difference with the natural product.

Other known systems, such as the one described in the international patent application with publication number W02005/090034 by the same applicant as the present application, provides for depositing, on a horizontal conveyor belt, a layer of almost constant thickness of powders having a base colour and for engraving the surface of such layer in order to create channels with an irregular pattern on the surface which are subsequently filled with powders of a different colour to the base colour. The powder layer is engraved by an engraver or a mobile suction element along a plane parallel to the plane of the conveyor belt.

Document WO 2018/122755 describes an apparatus for the production of slabs. The apparatus comprises means for feeding the material to be formed, first collection and movement means, a transport box and second collection and movement means. The feeding means for the material to be formed take the material to be formed from the tanks and deposit it on a first conveyor to form a semi-finished layer. According to the invention, the transport box comprises at least one flap suitable to cross the entire thickness of the flow of material to be formed, which, in use, passes through the transport box.

US 5554393 describes an apparatus for forming a layer of a predefined thickness on a given surface and comprises an endless pattern-forming device having a plurality of spaces, a device for feeding particles into the spaces, a device to temporarily retain the particles supplied in the spaces and to release the particles temporarily retained on a given surface.

However, generally speaking, the above methods, although capable of producing veins of a colour different from the base colour, determine a clear chromatic difference between the base colour and the colour of the vein, which is not very natural and is unattractive.

In addition, these methods usually produce the vein on the same belt that brings the powder layer to a pressing station and then through a firing step. Therefore, once the slab is finished, the veins will be linear and not very natural, as if deposited inside channels.

Lastly, these methods give rise to technical problems during the pressing step, as they do not (effectively) allow the use of powders of different granularity (e.g. atomised for the base layer and micronized for the veins) , which would require different pressing methods, as a micronized powder must be pressed more than atomised powder to achieve the same density. This lack of equal density leads to a weakening of the ceramic product where the micronized powder, i.e. the vein is. The purpose of the present invention is to provide a method and apparatus for the production of ceramic products, in particular for the production of ceramic products with internal streaks or veins, which are at least partially free of the aforementioned drawbacks and, at the same time, are simple and economical to make.

SUMMARY

According to the present invention, a method and apparatus are provided for the production of ceramic products, in particular for the production of ceramic products with internal streaks or veins, as claimed in the following independent claims and, preferably, in any of the claims dependent directly or indirectly on the independent claims .

The claims describe preferred embodiments of the present invention, forming an integral portion of the present description .

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the appended drawings, which illustrate some, non-limiting embodiments, wherein:

• Figure 1 is a schematic side view of a first embodiment of an apparatus for making products according to the present invention;

Figure 2 is a plan and schematic view of a part of the apparatus in Figure 1;

• Figure 3 is a perspective and schematic view of the part in Figure 2;

• Figure 4 is a plan and schematic view of a second part of the apparatus in Figure 1;

• Figure 5 is a plan and schematic view of a second embodiment of an apparatus according to the present invention; and

• Figure 6 is a perspective and schematic view of a product exiting the apparatus in Figure 1.

DETAILED DESCRIPTION

In Figure 1, reference numeral 1 globally denotes an apparatus for the production of ceramic products 2.

the apparatus 1 comprises a work assembly 3, which, in turn, comprises a pressing device 4 configured to compress a powder material 5 so as to obtain a layer 6 of compacted powder material.

In particular (Figures 2, 3, 5, and 6), the powder material 5 comprises different ceramic powders 7 and 8 (in particular, different-coloured ones) .

Advantageously but not necessarily, the pressing device 4 comprises (is) a pressing belt 9 (Figure 1), more precisely a pair of opposite pressing belts 9, which are arranged so as to be progressively closer to each other (in particular to compress the powdered material 5 so as to obtain a desired density) in a conveying direction D.

The apparatus 1 further comprises a conveyor assembly 10, in particular comprising a conveyor belt 11 moving in the conveying direction D (substantially horizontal) . More specifically, the conveyor assembly 10 (the conveyor belt 11) determines a conveying plane CP (substantially horizontal) .

In addition, the apparatus 1 comprises a supplying assembly 12 configured to deposit the ceramic powder 7 on the conveyor belt 11 in order to obtain a base layer 13 (in particular, arranged on the conveying plane CP) .

According to some non-limiting embodiments, the supplying assembly 12 comprises (is) a hopper 14.

Advantageously but not necessarily, the supplying assembly 12 is shaped so that the base layer 13 has a (substantially) constant thickness.

According to some non-limiting embodiments, as illustrated for example in Figures 1 to 3, the apparatus 1 further comprises a removal assembly 15, which in turn comprises at least one removal device 16 configured to remove (in particular, by suction) at least part of the ceramic powder 7 so as to obtain at least one groove 17 in the base layer 13.

Advantageously but not necessarily, the removal device 16 is mobile in at least one further direction T transverse to the conveying direction D and substantially parallel to the conveying plane CP.

In particular, by combining the movement of the removal device 16 and the conveyor belt 11, it is possible to generate grooves 17 along the entire base layer 13. In other words, by moving the base layer (which defines the X axis of a Cartesian plane coinciding with the conveying plane CP) and moving the removal device 16 (which defines the Y axis of a Cartesian plane coinciding with the conveying plane CP), it is possible to identify a motion law (in X-Y) which defines the (desired) shape of the groove 17.

Advantageously but not necessarily, the removal device 16 is also mobile in a direction N perpendicular to the conveying plane CP. In this way, the removal device 16 is also able to generate discontinuous grooves 17 in the base layer 13 (if such movement along N is not possible, the grooves 17 are, of course, continuous) . More precisely, the removal device 16 can be activated (in this case, in use, it sucks up the powder 7) and deactivated (in this case, in use, it does not suck up the powder 7) .

According to other non-limiting embodiments, the apparatus 1 (more precisely, the removal assembly 15) comprises a plurality (for example three, as shown in Figure 5) of removal devices 16.

According to further non-limiting embodiments not shown, the apparatus 1 comprises a different number of removal assemblies 15 (and therefore of removal devices 16) .

In addition, the apparatus 1 comprises a deposition assembly 18 which is configured to deposit the ceramic powder 8, which is different from the other ceramic powder 7, into the groove 17 so as to obtain a combined layer (comprising the ceramic powders 7 and 8) . In particular, the ceramic powder 8 is a different colour from the other ceramic powder 7.

Advantageously but not necessarily, the removal assembly 15 and the deposition assembly 18 are configured so that the quantity of powder 8 inserted in the groove 17 is less than or equal to the quantity of powder 7 sucked up by the removal device 16.

In particular, the removal assembly 15 and the deposition assembly 18 are configured so that the quantity of powder 8 inserted in the groove 17 is less than half of the quantity of powder 7 sucked up by the removal device 16. In this way, it is possible to obtain a ceramic product 2 with a thin vein 19 (as shown in Figures 4 and 6) , which presents reduced risks of compromising the stability of the ceramic product 2.

Advantageously but not necessarily, the deposition assembly 18 is positioned downstream of the removal assembly 15 (in particular, of the corresponding removal device 16) in the conveying direction D. This facilitates the deposition of the powder 8 inside the groove 17.

According to some non-limiting embodiments, as illustrated for example in Figures 1 to 3, the deposition assembly 18 comprises a delivering device 20 (in particular, mobile at least in the further direction T) . More precisely, the delivering device 20 is suitable for emitting the ceramic powder 8 (in particular, through an outlet nozzle thereof) .

According to other non-limiting embodiments, the apparatus 1 (more precisely, the deposition assembly 18) comprises a plurality (for example three, as shown in Figure 5) of delivering devices 20.

Advantageously but not necessarily, the delivering device 20 is also mobile in a direction N perpendicular to the conveying plane CP. In this way, the delivering device 20 is able to generate discontinuous veins 19 in the groove 17 in the base layer 13 (if such movement along N is not possible, the veins 19 are, of course, continuous) . In addition, by means of this movement in the direction N, the delivering device 20 can be positioned close to (or even in contact with) the conveyor belt 11, so as to accurately deposit the ceramic powder 8 inside the groove 17. More precisely, the delivering device 20 can be activated (in this case, in use, it delivers the powder 8) and deactivated (in this case, in use, it does not deliver the powder 8) . The apparatus 1 further comprises a feeding assembly 21, which is configured to receive the aforementioned combined layer (comprising the powders 7 8 - which together form the powder material 5) in particular from the conveyor assembly 10, and to feed the combined layer (powder 7 and powder 8) to (on) a conveyor assembly 25 (more precisely, on a conveyor belt 22 of the conveyor assembly 25) so as to form, (on the assembly 25, more precisely, on the belt 22) a (continuous) layer 23 of the powder material 5 comprising both the powder 7 and the ceramic powder 8.

More precisely, the feeding assembly 21 is configured to feed the combined layer (powder 7 and powder 8) crosswise and downwards to the conveying direction D (in particular, substantially vertically) to (on) the conveyor assembly 25 (more precisely, on the conveyor belt 22) so as to form the (continuous) layer 23 of the powder material 5.

In particular, the ( continuous ) layer 23 of powder material 5 has (at least partially) the vein 19 inside of it. More specifically, the feeding assembly 21 is configured to mix (partially) the powder 7 and the ceramic powder 8 and form the layer 23.

In other words, in some non-limiting cases, the conveyor assembly 10 is configured to feed the combined layer (powder 7 and ceramic powder 8 - which together form the powder material 5) to the feeding assembly 21. Advantageously but not necessarily, the feeding assembly 21 comprises (is) a hopper 24 located downstream of the conveyor assembly 10 (i.e. the conveyor belt 11) .

Advantageously but not necessarily, the conveyor belt 11 is in a higher position than the conveyor belt 22. In particular, by means of the feeding assembly 21 (i.e. the hopper 24), the powders 7 and 8 are partially mixed due to a drop that they undergo when passing from the belt 11 to the conveyor assembly 25 (more precisely, the conveyor belt 22) . Through this drop, the powders 7 and 8, which are arranged discontinuously on the conveyor belt 11, are amalgamated. In this way, the vein 19 inside the layer 23 on the conveyor assembly 25 (more precisely, on the conveyor belt 22), is (at least partially) partially mixed with the base layer 13, resulting in a nuanced colour effect and a similar appearance to that of natural stone (or wood) . In other words, this drop evens out the powders 7 and 8 to form a more homogeneous powder material 5 on the conveyor assembly 25 than the combination of powders 7 and 8 present on the conveyor assembly 10.

In particular, the term "drop" refers to a movement of the ceramic powders 7 and 8, substantially perpendicular to the conveying plane CP (in other words, vertical) . More precisely, a movement that uses the force of gravity is meant. Even more precisely, but not necessarily, a substantially straight movement is meant.

Advantageously but not necessarily, the feeding assembly 21 is configured so that the (continuous) layer of powder material 5 has a substantially constant thickness.

According to some embodiments, such as the one illustrated in Figure 1, the apparatus 1 comprises the conveyor assembly 25, the conveyor belt 22 of which is mobile in the conveying direction D (according to other embodiments not illustrated, the belt 22 is mobile in any direction - advantageously but not necessarily horizontal - longitudinal to the conveyor belt 22) . More precisely, the conveyor assembly 25 is configured to bring the powder material 5 (even more precisely, the layer 23) from the feeding assembly 21 to the working assembly 3 (i.e. to the pressing device 4) .

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figure 1, the apparatus 1 also comprises a cutting assembly CA to cut the layer 6 in compacted powdered material in order to obtain slabs 27. In particular, the cutting assembly CA is located downstream (with respect to the direction D) of the working assembly 3.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figure 1, the apparatus 1 comprises a firing assembly 26, arranged downstream (with respect to the direction D) of the working assembly 3 and configured to fire the layer 6 of compacted powder material (or, more precisely, the slabs 27) and obtain the ceramic products 2. According to some non-limiting embodiments, the firing assembly 26 is located downstream (with respect to the direction D) of the aforementioned cutting assembly CA.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figure 1, the apparatus 1 comprises a printing assembly 28, which is arranged downstream of the working assembly 3 and in turn comprises a digital printing device 29, which is configured to produce, on the layer 6 of compacted powder material (or, more precisely, on the slabs 27), and depending on a position of the ceramic powder 8, an image 30 comprising at least one decorative element E (e.g. at least one surface vein - see, in particular, Figures 4 and 6) .

In particular, the position of the decorative element E is coordinated with the position of the ceramic powder 8 (and therefore the vein 19) . More specifically, the position of the decorative element E at least partially overlaps the position of the ceramic powder 8 (and therefore the vein 19) .

According to some non-limiting embodiments, such as the one shown in Figure 6, the image 30 is the image of a natural stone, in particular marble.

According to other non-limiting embodiments not shown, the image 30 is the image of wood or any other surface decoration of the layer 6 of compacted powder material.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiments of the appended drawings, the apparatus comprises a plurality of suction devices 16 and a plurality of delivering devices 20. In particular, each removal device 16 is associated with a delivering device 20. More precisely, each removal device 16 is integral with the respective delivering device 20.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figures 1 to 3, the apparatus 1 (more precisely, the removal assembly 15 and/or the deposition assembly 18) comprises an arm 31, which is mobile at least along said further direction T and on which the removal device 16 and the delivering device 20 are mounted .

According to some non-limiting embodiments, the apparatus 1 comprises a number of independent movable arms 31, each equipped with the respective removal device 16 and the respective delivering device 20.

According to other non-limiting embodiments, such as the one shown in Figure 5, the suction devices 16 and the respective delivering devices 20 are separate, in particular, the delivering devices 20 are downstream (with respect to the conveying direction D) of the suction devices 16.

According to other non-limiting embodiments not illustrated, the number of suction devices 16 is different from the number of delivering devices 20, for example in the case where a delivering device 20 inserts the ceramic powder 8 inside two grooves 17 made by two different suction devices 16.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figure 1, the apparatus 1 comprises a recirculation system 32 configured to bring back to the supplying assembly 12 the powder 7 which, in use, the removal device 16 sucks up from the base layer 13. In this way it is possible to reduce the consumption (and costs) of ceramic powder 7 and improve the environmental sustainability of the apparatus 1.

In some cases, the apparatus 1 also comprises a delivering assembly 35 which is controlled by a control device CD to feed an additional quantity of ceramic powder 7 (or 8) to the conveyor assembly 10 in order to vary (over time) the quantity of ceramic powder 7 (or 8) supplied by the feeding assembly 21 to the conveyor assembly 10 according to what is detected by a detection device 36. In particular, the delivering assembly 35 is placed between the hopper 24 and the work station 33 and feeds the ceramic powder 7 (or 8) onto the aforementioned powder material 5. In some cases, the delivering assembly 35 comprises a number of delivering devices, which are arranged transversely to one another (in particular, perpendicularly) in the direction D and can each be activated independently of the others so as to feed additional (variable) amounts of ceramic powder 7 (or 8) downwards onto the powder material 5.

More precisely, the delivering devices are arranged along a transverse direction (in particular, substantially perpendicular) to the direction D.

In particular, the delivering assembly 35 comprises at least one hopper 37 equipped with a number of lower openings (only one of which is shown schematically in Figure 1) and suitable for containing ceramic powder 7 (or 8) . Each delivering device consists of a distribution element 38 (more precisely, a thin plate) placed (slightly spaced apart) below a respective lower opening so that ceramic powder 7 (or 8) can accumulate on the distribution element; and a vibrating device (not shown) designed to selectively vibrate the distribution element 38 so that the ceramic powder 7 (or 8) accumulated on the distribution element 38 slides and falls downwards. The control device CD is configured to selectively activate each vibrator device independently of the other vibrator devices.

According to specific embodiments, the delivering assembly 35 is like the delivering device described in the patent application with publication number W02009118611 (by the same applicant as this application) . In particular, the apparatus 1 may comprise devices for smoothing the powder material 5 as described in the patent application with publication number WO2017216725.

In addition or as an alternative to the delivering assembly 35, according to some embodiments, the apparatus 1 also comprises a removal assembly 39, which is controlled by the control device CD to remove part of the powder material 5 (fed from the hopper 24 to the conveyor assembly 10) in order to vary the amount of ceramic powder 7 (or 8) (i.e. of powder material 5) supplied by the feeding assembly 21 to the conveyor assembly 10 according to what is detected by the detection device 36. The removal assembly 39 is located between the hopper 24 (in some cases, the delivering assembly 35) and the work station 33. More precisely, the removal assembly 39 is suitable for removing ceramic powder from the above-mentioned layer of powder material 5.

According to a second aspect of the present invention, a method is provided for the production of ceramic products 2, in particular for the production of ceramic products 2 with internal streaks or veins 19. In particular, the method is implemented by the apparatus 1 described above.

The method comprises a compacting step, during which, in the area of a work station 33, the powder material 5 (more precisely, the layer 23) comprising the ceramic powders 7 and 8 is compacted so as to obtain the layer 6 of compacted powder material.

In addition, the method comprises a supplying step, during which the ceramic powder 7 is fed to the conveyor assembly 10 thus determining the base layer 13. In particular, the base layer 13 is formed with a substantially constant thickness.

During the supplying step, the conveyor assembly 10 conveys the base layer 13 towards (in particular, to) the feeding assembly 21. More precisely, the conveyor assembly 10 moves the base layer 13 in the conveying direction D (in particular, substantially horizontal) .

According to some non-limiting embodiments, the conveyor assembly 10 defines the conveying plane CP (in particular, substantially horizontal) . More precisely (during the supplying step) , the base layer 13 is placed and moves on the conveying plane CP.

Advantageously but not necessarily, in use, the base layer 13 is moved substantially continuously, in particular at an almost constant speed (excluding, of course, the start up and shutdown steps of the apparatus 1) .

The method also comprises a removal step, during which the removal device 16 removes (in particular, by suction) at least part of the ceramic powder 7 so as to obtain at least the groove 17 in the base layer 13.

According to some non-limiting embodiments, the removal device 16 is moved (at least) in the direction T to remove, in particular by suction, (at least) part of the ceramic powder 7 and thus determining the groove 17 in the base layer 13.

The method also comprises: a deposition step, during which the delivering device 16 (which, in particular, moves along the groove 17) deposits, inside the groove 17, the ceramic powder 8, which is different (in particular, a different colour) from the ceramic powder 7, so as to obtain a combined layer; and a feeding step, during which the combined layer (i.e. the ceramic powders 7 and 8 respectively deposited by the supplying assembly 12 and the delivering device 20) is fed (in particular by dropping) by the feeding assembly 21 to the conveyor assembly 25 forming the layer 23 (in particular, continuous) of the powder material 5 (on the assembly 25, in particular on the belt 13) . In particular, during the feeding step the combined layer (i.e. the ceramic powders 7 and 8) is fed by means of the feeding assembly 21 crosswise in the direction D downwards (in particular, vertically) to the conveyor assemb1y 25.

In addition, the method comprises a conveying step, during which the powder material 5 (more precisely, the layer 23) is conveyed by the conveyor assembly 25 from the feeding assembly 21 to the work station 33 (in particular in the conveying direction D) .

In some non-limiting cases, the supplying step, the conveying step, and the feeding step are (at least partially) simultaneous .

Advantageously but not necessarily (during the removal step), the removal device 16 removes at least part of the first powder 7 by suction.

Advantageously but not necessarily, and as illustrated in the non-limiting embodiment in Figures 2 and 3, the groove 17 is a through groove and divides the base layer 13 into (at least) two separate sections. In this way, the vein 19 can be distributed over the entire thickness of the layer 23 of the powder material 5, i.e. therefore also of the finished ceramic product 2.

According to some non-limiting embodiments, the removal step and the deposition step are (at least partially) simultaneous (or immediately successive - less than five seconds apart) . In this way it is possible to speed up the process because, as soon as a groove 17 is made by the removal device 16, the delivering device 20 deposits the ceramic powder 8 used to create the vein 19. In addition, this reduces the risk that part of the groove 17 collapses before the ceramic powder 8 is deposited.

Advantageously but not necessarily, the removal device 16 and the delivering device 20 follow the same motion law (at least) along the direction T. In particular, the removal device 16 and the delivering device 20 follow the same motion law in all directions in which they can move. More precisely, the delivering device 20 follows the same motion law as the removal device 16 with a predetermined delay.

In particular, the removal device 16 and the delivering device 20 are moved by the same actuator system 34. More specifically, the removal device 16 and the delivering device 30 are integral with each other.

Advantageously but not necessarily, the conveyor belt 11 is moved (by a control unit not shown) at a speed VI and the conveyor belt 22 is moved at a different speed V2. More precisely, the ratio between the first speed VI and the second speed V2 is substantially constant. In particular, the first speed VI and the second speed V2 are equal to each other .

Advantageously but not necessarily, at full speed, the conveyor belt 11 and/or the second conveyor belt 22 move at a constant speed.

According to some non-limiting embodiments, the method comprises a cutting step, during which the layer 6 is cut so as to obtain at least one slab 27 (which is a portion of the layer 6) .

According to some non-limiting embodiments, the method comprises a firing step, subsequent to the compacting step (and, in particular, subsequent to the cutting step) and during which the layer 6 of compacted powder material (more precisely, the slab 27) is fired to form a fired slab 27 ( the product 2 ) .

Advantageously but not necessarily, the method further comprises a printing step, during which the digital printing device 29 prints, depending on the position of the ceramic powder 8 in the layer 6 of compacted powder material, an image 30 comprising (at least) the decorative element E, on the layer 6 of compacted powder material (or on the slab 27) . In particular, the decorative element E is a superficial vein.

Advantageously but not necessarily the position of the decorative element E is coordinated with the position of the ceramic powder 6. More precisely, the position of the decorative element E at least partially overlaps the position of the ceramic powder 8 (i.e. the vein 19 generated by it after the drop) .

According to some non-limiting embodiments such as those in the appended drawings, the image 30 is the image of a natural stone (plaster, granite, marble, etc.) .

According to other non-limiting embodiments not illustrated, the image 30 is the image of a wooden board (also with its veins 19) .

Advantageously but not necessarily, the position of the ceramic powder 8 is a position detected, in particular by a visual system.

Advantageously but not necessarily, the first ceramic powder 7 is an atomized powder and the second ceramic powder 8 is a micronized powder. In this way, the smaller grain size of the powder 8 allows a vein 19 with a higher definition to be made than a vein 19 made using atomised powder.

In particular, the micronized powders (e.g. in porcelain stoneware) are obtained from standard-type atomized powders that are ground by micronizing mills (high speed rotating mills fitted with pegs or other elements suitable for violently impacting the incoming powders and effectively fragmenting them) . The micronized powders can be of the same colour as the initial atomized powders, or, starting from a mixture of two or more atomized colours, a new intermediate shade between the initial ones can be created (e.g. by mixing 50% white atomized and 50% black atomized and sending the mixture to a micronizer mill, a micronized powder with an intermediate grey tone is obtained) .

More specifically, the typical grain size of micronized powders, much finer than atomized (the grain size of which is usually in the range of 200 - 500 mpi) , ranges between 40 - 180 mpi .

In particular, the particle sizes are measured as an average diameter D(v.0.5) using a laser granulometer - in particular, using a Mastersizer Microplus Ver.2.19 (Malvern Instruments ^® Ltd) laser granulometer. More precisely, the particle sizes are measured according to what is required by the ISO 13320:2009 standard.

In particular, in some non-limiting cases wherein the powders 7 and 8 have a different granularity, the drop also determines a greater cohesion between the vein 19 and the base layer 13 (the atomized particles of powder 7 partially mix with the micronized particles of the powder 8, increasing the final compactness of the ceramic product 2) .

Advantageously but not necessarily, the delivering device 16 delivers into the groove 17, a plurality of different ceramic powders 8 (e.g. of different colours and/or dimensions) . In particular, the plurality of ceramic powders 8 is delivered in such a way as to determine at least one colour shading. In this way, the visual effect of the vein 19 is more attractive as it is more similar to natural stone.

In use, the ceramic powder 7 is distributed on the conveyor belt 11 so as to form the base layer 13. While this base layer 13 slides along the conveyor belt 11, the removal device 16 generates the groove 17 by sucking up some of the powder 7 and the delivering device 20 deposits the powder 8 inside the groove 17.

The powders 7 and 8 on the conveyor belt 11 are dropped inside the hopper 24, which deposits on the conveyor belt 22 the layer 23 (continuous) of material 5 composed of the base layer 13 and the vein 19. This layer 23 is then pressed by the pressing belt 9, generating the layer 6 of compacted powder material 5. Continuing its path, the surface of the layer 6 is printed by the digital printing device 29 so as to reproduce the image 30 having at least a graphic effect E on the vein 19. Subsequently, the printed layer 6 of compacted powder material 5 passes through the firing assembly 26, in particular making the ceramic product 2.

Advantageously but not necessarily, the apparatus 1 described above is configured to implement the method described above.

Although the invention described above makes particular reference to a precise embodiment, it is not to be considered limited to such embodiment, all those variants, modifications, or simplifications, which would be evident to the person skilled in the art, falling within its scope. These include, for example: the use of a different number or a different arrangement of the removal and delivering devices, different conveyor assemblies, or different conveying directions etc. The present invention has several advantages. First of all, it creates a more realistic imitation of a vein found in natural objects, since the drop arranges the powder 8 (which defines the veining) in a random and, therefore, more natural manner.

In addition, the drop also improves the visual appearance (as well as the randomness of the shape of the vein), including in terms of colour. In fact, even if the powder 8 is deposited in a through groove and therefore possibly not in contact with the base layer 13, the powders 7 and 8 will partially tend to mix in the external areas of the vein 19, and this allows a less sharp and more natural chromatic difference.

In addition, through the use of a micronized powder 8 it is possible to obtain a high-resolution vein (the typical shots of atomized powders - larger ones - are not visible) and the deposition of a low quantity of micronized powder 8 favours the solidity of the finished ceramic product 2 because it is not necessary (also due to the partial mixing of atomized and micronized particles) to press the two types of particles in a distinct manner.

Lastly, the present invention makes it possible to create a digital image synchronized with the vein (which will be visible from the edge of the product) despite the randomness of its arrangement due to the drop. Unless expressly indicated to the contrary, the contents of the references (articles, books, and patent applications etc.) cited in this text are herein referred to in full. In particular, the above-mentioned references are herein incorporated for reference.