EQUIPMENT FOR ROTARY SERIGRAPHY, PARTICULARLY FOR DECORATING THE SURFACES OF CERAMIC PRODUCTS, AND RELEVANT MANUFACTURING PROCESS

Technical Field The present invention relates to an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like.

The present invention moreover relates to the manufacturing process of the above equipment. Background Art

With particular but not specific reference to the ceramic industry, the serigraphy technique is known used to convey a decorative design onto the visible surface of substantially flat elements, such as, for example, ceramic tiles and slabs.

This printing technique is habitually implemented by means of specific equipment, which can be split into two different categories: equipment for flat serigraphy and that for rotary serigraphy.

In the case of rotary serigraphy, in particular, product printing is done by rotating around its own axis a roller, the outer surface of which is shaped and defines the design to be conveyed onto the products. The roller usually consists of a cylindrical support frame, which is obtained from steel plates, in the form of a continuous sheet or pre-perforated mesh, at the end of a rolling process.

To allow its future fitting on a machine suitable for roller rotation, the ends of the cylindrical frame are associated with two steel coupling rings. The side surface of the cylindrical frame is then covered with sponge of adequate thickness and, outside the sponge, a layer of silicone is applied.

The surface of the silicone layer is purposely engraved and, once rotation starts together with the support frame, it is able to convey the pre-engraved design or image onto the ceramic product. This equipment of known type does have several drawbacks.

In this respect, the fact should be considered that the rolling operation for sculpting the cylindrical frame consists in bringing closer together and

superimposing two opposite edges of the steel plate.

The joining section of the two edges involves the formation of a discontinuity point on the cylindrical frame, at which point the thickness and the weight of the frame is substantially greater. Furthermore, due to the limits of precision of the rolling operation itself, the cylindrical frame can have eccentricity and ovalization faults. All this contributes to obtaining a support frame that is not perfectly cylindrical and balanced with respect to its axis which, therefore, can cause problems as regards coupling with the coupling rings and lack of precision during use, during rotation and transfer of the image onto the ceramic products.

Furthermore, it should not be overlooked that the rollers for printing ceramic products obtained with traditional support frames, generally have a fairly heavy overall weight, which makes them less handy to use and reduces mobility both during the installation phase and during machine use. It must furthermore be underlined that the traditional roller manufacturing process is particularly costly. Object of the Invention

The main aim of the present invention is to provide an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like, which has a very simple design, is easy to assemble, has a limited weight and permits achieving top-quality and precise printing.

A further object of the present invention is to provide a manufacturing process of an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like that is particularly practical and easy.

Another object of the present invention is to provide an equipment and a manufacturing process that permit overcoming the mentioned drawbacks of the background art as part of a simple, rational and low cost solution. The above-indicated objects are all achieved by the present equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like, characterized in that it comprises at least one

round-section tubular element in glass-reinforced plastic and at least one superficially-shaped layer according to a pre-established design for the serigraphy of products, which can be associated at least partially with the outer side surface of said tubular element. The above-indicated objects are further achieved by the present manufacturing process of an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like, characterized in that it comprises the following steps:

- wrapping at least one flexible sheet in fibrous material around a substantially cylindrical matrix;

- allowing said sheet to harden around said matrix to represent at least one rigid tubular element in glass-reinforced plastic;

- removing said matrix from said tubular element;

- covering, at least partially, the outer side surface of said tubular element with at least one superficially-shaped layer according to a pre-established design for the serigraphy of products.

Brief Description of the Drawings

Further characteristics and advantages of the present invention will appear more evident from the detailed description of a preferred but not exclusive embodiment of a manufacturing process of an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like, illustrated indicatively by way of non limiting example, in the attached drawings wherein: the figure 1 is an axonometric view that shows the wrapping phase of the flexible sheet around the cylindrical matrix as provided by the process according to the invention; the figure 2 is an axonometric view that shows the hardening phase of the flexible sheet around the cylindrical matrix as provided by the process according to the invention; the figure 3 is an axonometric view that shows the separation phase of the cylindrical matrix and the tubular element as provided by the process according to the invention;

the figure 4 is an axonometric view that shows the covering phase of the tubular element as provided by the process according to the invention; the figure 5 is an axonometric view that shows the application phase of the ring- shaped elements at the ends of the tubular element as provided by the process according to the invention. Embodiments of the Invention

With particular reference to such illustrations, the reference I has been used to globally indicate the first phase of the manufacturing process according to the invention, which involves the wrapping of one or more flexible sheets 1 in fibrous material around the side surface of a metal matrix 2 which has the shape of a straight cylinder.

This first phase, in detail, consists in spiral rolling the flexible sheets 1 around the metal matrix 2 and repeating several passages of the spiral, for example by superimposing one sheet 1 on another and/or superimposing the spirals of a same sheet 1 , until a pre-established thickness is reached.

Usefully, the fibrous material making up the flexible sheets 1 is selected from the list comprising: glass fibres, carbon fibres and kevlar®. The second phase II of the process according to the invention consists in allowing the flexible sheets 1 to harden around the metal matrix 2 so as to constitute a rigid tubular element 3, with a round section and made of glass- reinforced plastic.

This second phase involves spreading the flexible sheets 1 wound around the metal matrix 2 with a hardening resin 4, of the synthetic or natural type, by means of a spraying operation, using a plurality of spray nozzles 5. The combination of hardening resin 4 and the fibrous material of the flexible sheets 1 results in the formation of the glass-reinforced plastic that makes up the tubular element 3.

As an alternative to the spraying technique, the hardening resin 4 can be applied to the flexible sheets 1 by means of a brush. The third phase III of the process involves the separation of the metal matrix 2 and of the tubular element 3, done by removing the metal matrix 2 from the tubular element 3.

The fourth phase IV of the process consists in covering at least partially the outer side surface of the tubular element 3 with a superficially-shaped layer 6, which on the outside has one or more pre-established designs 7, in relief or grooved, that have to be reproduced on the products during serigraphy. The superficially-shaped layer 6 is made of engraved silicone, for example by means of a photo-engraving operation.

Usefully, the fourth phase IV of the process envisages that a layer of deformable material 8, for example of the substantially spongy type, be placed between the tubular element 3 and the superficially-shaped layer 6. The fifth and last phase V of the manufacturing process according to the invention is illustrated in figure 5 and consists in fitting coupling means 9 to the ends of the tubular element 3.

These are made up of a pair of ring-shaped elements with the same diameter dimensions as those of the tubular element 3 and feature a slot 10 suitable for allowing the interlock coupling with the ends of the tubular element 3.

The coupling means 9, in detail, allow fitting the tubular element 3 on a machine for serigraphy products featuring devices able to start the rotation of the tubular element 3 around its own axis. What is obtained at the end of the manufacturing process is an equipment for rotary serigraphy, particularly for decorating the surfaces of ceramic products such as tiles, bricks, slabs or the like.

Such equipment is made up of the assembly of the tubular element 3 which acts as a support frame, the intermediate layer of deformable material 8, the superficially-shaped layer 6 and the coupling means 9, as previously described and illustrated.

It has in fact been seen how the described invention achieves the set objects. The invention thus conceived is susceptible of numerous modifications and variations, all of which falling within the scope of the inventive concept. Furthermore all the details may be replaced by other elements which are technically equivalent.

In practice, the materials used as well as the contingent shapes and dimensions may be any according to requirements without because of this moving outside

the protection scope of the following claims.