Procedure for obtaining coated press plates for the manufacture of structured ceramic slabs

Abstract

A method for obtaining coated pressing plates for the manufacture of structured ceramic slabs, comprising at least the following steps: - supplying (A) at least one plate to be coated (1) adapted for pressing the ceramic powder material and provided with a first face (1a) to be coated and a second face (1b) opposite the first face (1a); - applying (D) at least one coating layer (3) onto the first face (1a) to obtain a pre-machined plate (4); - grinding the coating layer (3); - etching (F) the coating layer (3) to define on the latter at least one structured surface (3a) adapted to obtain at least one structured slab. Preferably, the method also comprises the steps of: abrasion (B) of the first face (1a); heating (C) of the plate to be coated (1); consolidation (E) by heating the coating layer (3) on the first face (1a).

Description

Procedure for obtaining coated press plates for the manufacture of structured ceramic slabs Technical field The present invention relates to a process for obtaining coated pressing plates for the manufacture of structured ceramic slabs, i.e., ceramic slabs whose surface, instead of being smooth and uniform, has grooves, reliefs, depressions, cuts and / or slots that give it a three-dimensional appearance. Background of the technique As is well known, the manufacture of structured ceramic slabs generally involves a phase of depositing a powdered material, which may consist of ceramic materials or a mixture of mineral compounds in granular form (e.g., marble and granite), glass, quartz powder, etc., as well as resins that act as binders, onto a support surface, such as a conveyor belt or mold, to form a slab to be compacted, and a subsequent pressing phase to obtain a compacted slab. Depending on the case, further phases are then planned, such as firing and subsequent cooling, to obtain a product with special mechanical and physical properties. Therefore, the equipment necessary to carry out these phases includes at least the presence of a support surface, movable in a direction of advance, on which the slab to be compacted is placed, and pressing means to press the slab to be compacted and obtain a compacted slab. The pressing means of a known type comprise a fluid-driven cylinder provided with a piston, displaceable with respect to the main body of the fluid-driven cylinder itself towards / away from the support surface(s) and to which a pressing plate is associated. Specifically, the pressing plate comprises a pressing surface, oriented towards the support surface and designed to come into contact with the ceramic material of the slab to be compacted. The current working method consists of coating the pressing surface of the plate by adhering one or more layers of bakelite, which gives the slabs the specific three-dimensional appearance sought as a result of pressing. However, it has been observed that the bonding process of bakelite is quite difficult and frequently causes the formation of air bubbles between the bakelite layer and the plate, which ends up affecting the aesthetic quality of the resulting structured slabs. It is easy to see how such a problem can lead to the formation of structured slabs with an appearance that differs from the desired one and, therefore, require further machining or even have to be discarded, with the consequent increase in production costs. Description of the invention The main objective of the present invention is to devise a procedure for obtaining coated press plates for the manufacture of structured ceramic slabs that allows the press plates to be effectively coated, avoiding the defects that characterize the procedures used to date, in order to achieve a high aesthetic quality of the manufactured structured slabs. Another object of the present invention is to devise a procedure for obtaining coated pressing plates for the manufacture of structured ceramic slabs that allows overcoming the aforementioned drawbacks of the prior art within the framework of a simple, rational, easy-to-use and effective solution that is also economical. The objects mentioned are obtained by this procedure for obtaining coated pressing plates for the manufacture of structured slabs of ceramic material that has the characteristics of claim 1. Brief description of the drawings Other features and advantages of the present invention will become more evident from the description of a preferred, but not exclusive, embodiment of a process for obtaining coated pressing plates for the manufacture of structured ceramic slabs, illustrated by way of non-limiting example in the accompanying drawings in which: Figure 1 shows the supply phase of the procedure according to the invention; Figure 2 shows the abrasion phase of the procedure according to the invention; Figure 3 shows the heating phase of the procedure according to the invention; Figure 4 shows the application phase of the procedure according to the invention; Figure 5 shows the consolidation phase of the procedure according to the invention; Figure 6 shows the engraving phase of the procedure according to the invention; Figure 7 shows as an example a machined plate obtained by means of the procedure according to the invention. Realizations of the invention With particular reference to these figures, the reference number 1 globally denotes a plate to be coated by the procedure according to the invention. The process for obtaining coated pressing plates for the manufacture of structured ceramic slabs comprises, firstly, at least one supply step A of at least one plate to be coated 1 adapted for pressing the ceramic powder material. Specifically, the plate to be coated 1 is provided with a first face 1a to be coated and a second face 1b opposite the first face 1a. Specifically, the first face 1a is in contact with the ceramic material to be compacted during use. Advantageously, a grinding phase is performed on the first face 1a of the plate to be coated 1. Preferably, the procedure then comprises at least one abrasion stage B of the first face 1a (see Figure 2). More specifically, the abrasion stage is performed after the grinding stage of the first face 1a. In the present case, the abrasion phase B comprises at least one sanding stage B of the first face 1a. This procedure allows cleaning and eroding the surface of the first face 1a, thus adequately preparing the latter for the following steps of the procedure that are briefly described. That said, it cannot be ruled out that the abrasion stage B may include, together with or instead of the sanding step B, one or more additional machining steps of the first face 1a, such as, for example, a shot blasting stage or the like. Advantageously, the process includes at least one heating stage C of the plate to be coated 1, which is shown as an example in Figure 3. Specifically, the heating phase C is carried out by special heating means 2 (as shown as an example in Figure 3) of the type of a ceramic kiln or other functionally similar devices known to the engineer in the field. Conveniently, the heating phase C is performed after the abrasion phase B. The provision of a heating phase C after sanding B is particularly useful, as it induces the thermal relaxation of the first face 1a, thus allowing the elimination of residual stresses in it and improving the adhesion quality of any of the coating layers on the latter. According to the invention, the process comprises at least one application step D, shown as an example in Figure 4, of at least one coating layer 3 on the first face 1a to obtain a pre-machined plate 4. In this regard, it should be noted that performing a sanding step B advantageously increases the roughness of the first face 1a and thus promotes the adhesion of the coating layer 3 to the latter during the application step D. Preferably, the coating layer 3 is made from a polymeric material, for example rubber, resin or similar. Advantageously, application phase D is carried out by pouring a liquid mixture onto the first face 1a. Specifically, application phase D is performed after abrasion phase B and heating phase C. Appropriately, the procedure then comprises at least one consolidation phase E of the coating layer 3 on the first face 1a. Specifically, the consolidation phase E, which is shown for illustrative purposes in Figure 5, comprises at least one heating stage E of the pre-machined plate 4. Again, the heating stage E is carried out using special consolidation means 5, such as a heating machine like a ceramic kiln or other functionally similar devices known to the engineer in the field. Specifically, the pre-machined plate 4, obtained from the application of the coating layer 3, is placed inside the heating machine to consolidate the coating layer. The consolidation stage E allows the mixture poured onto the first face 1a to solidify and further increases the adhesion of the coating layer 3 to the plate being coated 1. According to the invention, the procedure comprises at least one grinding phase of the coating layer 3 intended to increase the degree of surface finish of the coating layer itself. Specifically, the grinding phase is performed after the consolidation phase E. The grinding phase, therefore, allows the reduction of roughness and imperfections of the surface of the coating layer 3, facilitating the performance of subsequent work phases. In this sense, the procedure comprises at least one engraving phase F of the coating layer 3 (Figure 6) to define in it at least one structured surface 3 adapted to obtain at least one structured slab. Specifically, the engraving phase allows obtaining a structured surface 3a that has grooves, reliefs, depressions, cuts and / or slots that allow giving the structured slab its characteristic three-dimensional appearance. Conveniently, the etching phase F is performed after the grinding of the coating layer 3. As shown as an example in Figure 6, the engraving phase F is preferably carried out using laser engraving means, but different methodologies, known to technicians in the field, cannot be ruled out for achieving the structured surface 3a. Finally, the procedure comprises at least one heat treatment phase of the resulting structured surface 3a. Specifically, the heat treatment phase is performed after the engraving phase F and consists of placing the pre-machined plate 4 inside a heating machine. Advantageously, at least one of the consolidation E or heat treatment steps is carried out at a reference temperature between 50 °C and 120 °C. Preferably, the reference temperature is between 70 °C and 100 °C. This temperature range allows for very effective consolidation of the pre-machined plate 4 and stabilization of the structured surface 3a, while minimizing energy consumption. Therefore, the procedure we have just described allows us to obtain a machined plate 6, as shown in Figure 7 as an example, which is not subject to the formation of internal air bubbles and which can, for this reason, be used cost-effectively to form structured slabs that are distinguished by a remarkable aesthetic quality. In practice, it has been verified that the described invention achieves the intended objectives. In particular, it is worth highlighting that the procedure according to the invention allows for the effective coating of the pressed plates, thus avoiding the defects that characterize the processes used to date, allowing for a high aesthetic quality of the manufactured structured slabs. Specifically, the procedure according to the invention ensures the production of a coated plate that is not subject to the problem of air bubble formation and is therefore particularly suitable for the formation of structured slabs. In this sense, the plate obtained by the procedure of the present invention allows giving the structured slabs the exact desired aesthetic appearance and, therefore, means that they do not undergo any other treatment or machining after pressing, with a clear and advantageous reduction of the overall production costs.

Claims

1. A method for obtaining coated pressing plates for the manufacture of structured ceramic slabs, characterized in that it comprises at least the following steps: - supplying (A) at least one plate to be coated (1) adapted for pressing the ceramic powder material and provided with a first face (1a) to be coated and a second face (1b) opposite said first face (1a); - applying (D) at least one coating layer (3) onto said first face (1a) to obtain a pre-machined plate (4); - grinding said coating layer (3); - etching (F) of said coating layer (3) to define therein at least one structured surface (3a) adapted to obtain at least one structured slab.

2. A method according to claim 1, characterized in that it comprises at least one grinding step of said plate to be coated (1) performed prior to said application (D). 3.A method according to claim 1, characterized in that it comprises at least one abrasion step (B) of said first face (1a) performed prior to said application (D).

4. A method according to claim 2 or 3, characterized in that said abrasion (B) is performed after said grinding of the plate to be coated (1).

5. A method according to claim 3 or 4, characterized in that said abrasion step (B) comprises at least one sanding step (B) of said first face (1a).

6. A method according to one or more of the preceding claims, characterized in that it comprises at least one heating step (C) of said plate to be coated (1) performed prior to said application (D).

7. A method according to claim 6, characterized in that said heating step (C) is performed after said abrasion (B). 8.A method according to one or more of the preceding claims, characterized in that said application (D) is carried out by pouring the coating layer (3) in liquid form.

9. A method according to one or more of the preceding claims, characterized in that said coating layer (3) is made of a polymeric material.

10. A method according to one or more of the preceding claims, characterized in that it comprises at least one consolidation step (E) of said coating layer (3) onto said first face (1a).

11. A method according to claim 10, characterized in that said consolidation (E) comprises at least one heating step (E) of said pre-machined plate (4).

12. A method according to claim 10 or 11, characterized in that said grinding of the coating layer (3) is carried out after said consolidation (E) and prior to said etching (F). 13.A method according to one or more of the preceding claims, characterized in that said engraving (F) is performed by laser engraving means.

14. A method according to one or more of the preceding claims, characterized in that it comprises at least one heat treatment step of said structured surface (3a) performed subsequent to said engraving (F).

15. A method according to one or more of the preceding claims, characterized in that at least one of said heating step (E) or said heat treatment step is performed at a reference temperature between 50 °C and 120 °C.

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