WO2013150488A1

WO2013150488A1 - Cooling apparatus

Info

Publication number: WO2013150488A1
Application number: PCT/IB2013/052713
Authority: WO
Inventors: Andrea Debbia; Agostino ALLEGRO
Original assignee: Tek-Mak S.R.L.
Priority date: 2012-04-05
Filing date: 2013-04-04
Publication date: 2013-10-10

Abstract

A cooling apparatus for cooling products (100), in particular semifinished tiles, comprises containing means (2) defining an internal volume provided with an entry opening (11) and with an exit opening (12) for the products (100) and comprises, contained inside the internal volume, conveying means (3) for supporting and moving the products (100) through the internal volume along a movement plane (H), and fan means (4, 5) for directing air to the products (100); the apparatus further comprises a first portion (10), provided with the conveying means (3), and a second portion (20) connected to the first portion (10) so as to be movable between a closed position (C), wherein said first portion (10) and said second portion (20) are opposite and joined to enclose in the internal volume the conveying means (3), and an open position (B), wherein said first portion (10) and said second portion (20) are spaced apart to permit access to said conveying means (3) and/or to the products (100) positioned on the latter, said fan means (4, 5) being housed in said first portion (10) and/or in said second portion (20).

Description

Cooling apparatus

The invention relates to apparatuses for manufacturing tiles or shingles, and in particular it relates to a cooling apparatus for cooling the tiles during the manufacturing cycle thereof.

As it is known, the tiles or shingles are covering elements that are substantially flat and having a reduced thickness, obtained starting from a slurry of different materials, which is sequentially modeled or formed, dried, and then oven-fired in corresponding operative stations of a manufacturing plant.

The tiles are generally decorated by enameling processes or serigraphic processes. In the "single-fired" tiles, the modeled slurry, so-called "support", and the decoration are fired together in an oven. In this case, the enamel or the serigraphy are applied to the support exiting the drying station.

In the so-called "double-fired" tiles, in a first step the modeled and dried slurry is partially fired in a first oven, so as to create an intermediate product, referred to as "bisque", on which the decoration may be applied by means of enameling or serigraphy. In a second step, the bisque and the decoration are fired together in a second oven.

In both production processes (single-fired and double-fired), it is necessary to suitably cool the intermediate product or semifinished tile (the "support" exiting the drying station or the "bisque" exiting the first baking oven) before the application of the decoration.

In particular, in the case of the serigraphic processes, it has been found that the temperature decrease of the intermediate product, besides considerably increasing the printing quality, allows avoiding or limiting damages and wear of the serigraphic printing devices.

Currently, the cooling systems comprise fans or blowers capable of directing an air flow to the products exiting the drying station or the baking oven, moved on special conveying systems.

In order to allow a suitable cooling by using air at room temperature, the cooling time has to be suitable long. This determines a productivity decrease, or, in the case of continuous manufacturing processes, it requires a suitable length of the plant length on which the cooling operation is performed. Therefore, the plant turns out to be larger and bulky.

In order to obviate such drawbacks, cooling systems are known, in which the air is cooled by suitable thermal machines, such as air conditioners, or heat pumps of the household use type.

A drawback of the above-mentioned cooling systems is the low energy efficiency due to the fact that the cooled air, after skimming and cooling the products, is dispersed in the surrounding environment.

Another drawback is that the air cooled is substantially the air withdrawn from the environment, and it may contain particles, dust, pollutants that can compromise the decoration quality, in particular the printing quality of the serigraphic process.

A further drawback is given by the particular arrangement of the fans and/or air conditioners relative to a conveying system for the products, which arrangement makes difficult to an operator the access to the conveying systems itself, and thus to the products, in case of need.

An object of the present invention is to improve the known cooling systems that can be used in production plants of tiles for cooling intermediate products or semifinished tiles (supports or bisques) exiting from drying stations and/or baking ovens before the decoration processes, in particular serigraphic processes.

Another object is to create a cooling apparatus having a high energy efficiency and with reduced energy consumptions, which allows treating, and in particular cooling, in an optimal manner the products before the decoration process.

A further object is to create a cooling apparatus that allows cooling the products with clean air substantially free from particles, dust, pollutants, so as to obtain a high quality of the decoration.

Still another object is to obtain a cooling apparatus that is adjustable and configurable as a function of the format of the tiles, i.e., of the intermediate product, so as to optimize the corresponding cooling.

Still a further object is to create a reliable and safe apparatus that allows an easy accessibility to the conveying system of the products for inspection or maintenance operations.

In a first aspect of the invention, a cooling apparatus according to claim 1 is provided.

In a second aspect of the invention, a cooling apparatus according to claim 1 1 is provided.

The invention will be better understood and implemented with reference to the appended drawings, which illustrate some exemplary, non-limiting embodiments thereof, in which: Fig. 1 is a front view of the cooling apparatus of the invention in a closed configuration;

Fig. 2 is a side view of the apparatus of Fig. 1 ;

Fig. 3 is an enlarged section according to the line II I- III of Fig. 2; - Fig. 4 is an enlarged section according to the line IV-IV of Fig. 1 ;

Fig. 5 is a perspective front view of the apparatus of Fig. 1 in an open configuration;

Fig. 6 is an enlarged partial front view of the apparatus of Fig. 1 in the open configuration;

- Fig. 7 is a schematic section according to the line III-III of Fig. 2, in which some parts have been removed to better illustrate the air suction conduits and internal spaces;

Fig. 8 is a schematic section according to the line IV-IV of Fig. 1 , in which some parts have been removed to better illustrate the air suction conduits and the internal spaces.

With reference to the Figs. 1 to 8, the cooling apparatus 1 of the invention is illustrated, associable to a plant for manufacturing tiles for cooling intermediate products 100, in particular semifinished tiles, for example, formed slurries ("supports") exiting from drying stations or slurries formed and fired ("bisques") exiting from baking ovens before carrying out decoration processes, in particular serigraphic processes.

The apparatus 1 is substantially a cooling tunnel and comprises containing means 2 defining an internal volume provided with an entry opening 1 1 and with an opposite exit opening 12 for the entry and exit of the products 100. The apparatus 1 further comprises, contained inside the containing means 2, conveying means 3, for supporting and moving the products 100 through the above-mentioned internal volume from the entry opening 1 1 to the exit opening 12, fan means 4, 5 for directing air to the products 100 and diffusing means 8 interposed between the fan means 4, 5 and the conveying means 3 to intercept an air flow generated by the fan means 4, 5 and to create a plurality of air jets F directed to the products 100.

The apparatus further comprises heat exchanger means 6 for cooling the air directed on the products 100 and filter means 7 for filtering the air suctioned by the fan means 4, 5 and subsequently directed on the products 100 through the diffusing means 8.

The conveying means 3 comprises, for example, a chain or belt conveyor of a known type, capable of moving the products 100 along a forward direction A on a movement plane H.

The conveying means 3 slightly exits from the entry opening 1 1 and from the exit opening 12 of the containing means 2 to allow the transfer of the products 100 from/onto other conveying means of the manufacturing plant.

The conveying means 3 is actuated by motor means 35 fixed to an external wall of the containing means 2.

The fan means comprises first fan means 4 and second fan means 5 arranged opposite one to the other with respect to the movement plane H, in an operative configuration of said apparatus 1. The first fan means comprises at least one first axial fan 4 arranged beneath the conveying means 3 and the movement plane H. Similarly, the second fan means comprises at least one second axial fan 5 arranged above the conveying means 3 and the movement plane H. The first fan 4 and the second fan 5 are substantially the same. In the embodiment illustrated in the Figures, the first fan means comprises a pair of first fans 4 arranged side by side and spaced apart along the forward direction A, and the second fan means comprises a pair of second fans 5, also arranged side by side and spaced apart along the forward direction A.

The diffusing means comprising two diffusing elements 8 respectively interposed between the movement plane H and the first fans 4 and between the movement plane H and the second fans 5.

Each diffusing element 8 comprises a respective planar panel, or plate, fixed to internal walls of the containing means 2 and provided with slots 18 for the passage of the air flow. The slots 18 are enlarged through opening having a nearly rectangular shape, arranged transversally, in particular orthogonally, to the forward direction A. Deflecting means 19 is associated to each slot 18 for deviating and directing a corresponding air jet F to the products 100.

The two diffusing elements 8 define inside the containing means 2 (in the internal volume) a cooling chamber 15 traversed by the conveying means 3. The cooling chamber 1 is traversed by the air jets F coming from the deflecting means 19 that, arranged at both sides of the products 100, relative to the movement plane H, cools in an optimal manner opposite faces thereof.

The deflecting means 19 is configured and arranged for adjusting a passage section of the respective slot 18 and/or for deviating and directing and/or orienting the air jet F exiting the slot 19.

The deflecting means comprises an outlet port 19 that is shaped and connected to the respective slot 18 and substantially formed by two transversal peripheral tabs 19a and two longitudinal peripheral tabs 19b joined to form a rectangular frame. The passage section of the outlet port 19 is substantially equal to the passage section of the slot 18.

The outlet port 19 is inclined by a preset angle a with respect to the movement plane H. The angle a ranges, for example, between 90° and 30°, in particular, it is of about 70°.

In the illustrated embodiment, the outlet port 19 is inclined so as to send a flow F in a direction opposite to the forward direction of the products 100 to the inside of the apparatus 1 , from the entry opening 1 1 to the exit opening 12.

The inclination of the outlet port 19 can be modified and adjusted as required, and in particular as a function of the dimensions and the characteristics of the products 100.

In a variant not illustrated in the Figures, the deflecting means 19 further comprises one or more septums connected to the peripheral tabs 19a, 19b and slidable relative to the latter ones, to close or reduce the passage section of the respective slot 18. In this manner, it is possible to adjust also the dimensions of the passage section of the slots 18 as a function of the dimensions and the characteristics of the products 100 to optimize the efficiency of the apparatus.

The containing means 2 comprises first wall means 21 defining the internal volume and second wall means 22 that is external and containing the first wall means 21 , so as to form with the latter interspace means.

Separating means 23, 24 is fixed inside the containing means 2 and connected to, and supporting, the fan means 4, 5 so as to create with the containing means 2 a plurality of internal spaces 29-34. More precisely, the separating means comprises first separating means 23 supporting the first fans 4 and second separating means 24 supporting the second fans 5. The first separating means 23 comprises a plurality of respective septums or separating panels fixed to internal surfaces of the first wall means 21 and defining with the latter ones a first space 29, interposed between the first fans 4 and the respective diffusing element 8, a second space 30 interposed between the first fans 4 and the internal walls of the first wall means 21 and a third space 31 next to the first space 29 and the second space 30 and connected to the latter.

The first space 29 is traversed by the air flow blown by the first fans 4 towards the diffusing element 8 and the products 100; the second space 30 is traversed by the air suctioned by the first fans 4 and cooled by the respective exchanger means 6 arranged upstream; the third space 31 receives the air coming from the cooling chamber 15, as best explained in the following of the description. Similarly, the second divider means 24 comprises a plurality of respective separating panels fixed to internal surfaces of the first wall means 21 and defining with the latter ones a further first space 32, interposed between the second fans 5 and the respective diffusing element 8, a further second space 33, interposed between the second fans 5 and the internal walls of the first wall means 21 , and a further third space 34 next to the further first space 31 and to the further second space 32 and connected to the latter. The further first space 31 is traversed by the air flow blown by the second fans 5 towards the respective diffusing element 8 and the products 100; the further second space 32 is traversed by the air suctioned by the second fans 5 and cooled by the respective exchanger means 6 arranged upstream; the further third space 31 receives the air coming from the cooling chamber 15, as best explained in the following of the description.

The heat exchanger means comprises a pair of cooling unit 6 of a known type, for example, supplied with refrigerated water, positioned respectively at the passage between the second space 30 and the third space 31 and at the passage between the further second space 33 and the further third space 34, in both cases, upstream of the respective fan means 4, 5 relative to the air flow direction.

The apparatus further comprises filter means 7 for filtering the air suctioned by the fan means 4, 5 and subsequently directed to said products 100.

The filter means 7 is mounted next to the heat exchanger means 6, for example downstream thereof relative to the air movement direction.

The filter means comprises a pair of filtering units 7, of a known type, each of which being associated to a respective cooling unit 6. The filtering units 7 can be easily disassembled for a periodic replacement or cleaning.

The cooling apparatus 1 of the invention, by virtue of the diffusing means 8 provided with outlet ports 19 allows cooling in an optimal manner the intermediate products 100 that traverse the cooling chamber 15. In fact, the outlet ports 19 collect the air flow generated by the fans and create a plurality of concentrated and oriented air jets F that hit in an accurate manner both faces of the products 100 arranged on the conveying means 3. Furthermore, the inclination of the outlet ports 19 and the passage section of the slots 18 associated thereto can be modified and adjusted as a function of the dimensions and the characteristics of the products 100, so as to obtain a greater thermal exchange, thus a better cooling.

The apparatus 1 is formed by a first portion 10, provided with the conveying means 3, and by a second portion 20 connected to the first portion 10 so as to be movable between a closed position C, in which said portions 10, 20 are opposite and joined to enclose the conveying means 3 and to define the internal volume and the cooling chamber 15, and an open position B, in which the above-mentioned portions 10, 20 are spaced apart to permit access to the conveying means 3 and/or to the products 100 positioned thereon.

The second portion 20 is, in particular, rotatably connected to the first portion 10 and rotatable about an axis, in particular substantially parallel to the movement plane H and the forward direction A, between the closed position C and the open position B.

In a non-illustrated variant of the apparatus 1 of the invention, the second portion 20 can be rotatably connected to the first portion 10 and rotatable around an oblique axis with respect to the movement plane H and the forward direction A.

In a further non-illustrated variant of the apparatus 1 of the invention, the second portion 20 is slidably connected to the first portion 10 and movable relative to the latter, between the closed position C and the open position B, along a transversal direction, in particular orthogonal, to the movement plane H.

In still another non-illustrated variant of the apparatus 1 of the invention, the second portion 20 is slidably and rotatably connected to the first portion 10 and movable relative to the latter, between the closed position C and the open position B, linearly along a transversal direction, in particular orthogonal, to the movement plane H, in rotation around an axis transversal, in particular orthogonal, to the movement plane H.

The first portion 10 comprises, beside the conveying means 3, the first fan means 4, the first separating means 23 defining the first space 29, the second space 30 and the third space 31 and the respective diffusing means 8, exchanger means 6 and filter means 7. The second portion 20 comprises the second fan means 5, the second separating means 24, defining the further first space 32, the further second space 33 and the further third space 34 and the respective diffusing means 8, exchanger means 6 and filter means 7.

In the embodiment illustrated by way of example, in which the movement plane H is substantially horizontal, the first portion 10 is the lower portion resting on the ground, while the second portion 20 is the upper portion that closes like a book on the first portion 10.

The containing means 2 are divided in two parts, corresponding to the first portion 10 and the second portion 20, respectively.

Therefore, the cooling apparatus 1 of the invention, divided in two portions 10, 20 that can be separated and spaced apart, allows, in the case of a maintenance or stop, an easy access to the conveying means 3 and the products 100, for example, to remove an obstruction caused by the breakage of a product 100. This allows considerably reducing the downtimes of the apparatus and of the manufacturing plant in which said apparatus is inserted.

The apparatus 1 comprises conduit means 41 -46 arranged to withdraw or suction air from the cooling chamber 15, at the work plane H and to convey it to the heat exchanger means 6 and more precisely into the third spaces 31 , 34. The withdrawn air is heated after skimming the products 100 at a high temperature.

The conduit means 41 -46, which comprise a plurality of air suction conduits, are obtained and housed inside the interspace means, formed by the first wall means 21 and the second wall means 22 of the containing means 2.

The conduit means comprise first conduit means 41 , 42, 43 and second conduit means 44, 45, 46 arranged and contained respectively in the first portion 10 and in the second portion 20 (figure 7 and 8).

The first conduit means 41 , 42, 43 are connected to the cooling chamber 15 by means of a plurality of first suction openings 51.

The first conduit means comprise a plurality of first conduits 41 , which are housed in the interspace means at side portions of the containing means 2, open to the cooling chamber 15 through the first suction openings 51.

In the illustrated embodiment, the first conduits 41 are six in total, arranged three by three on the opposite sides of the containing means 2; the first conduits 41 are transversal and in particular nearly orthogonal to the movement plane H.

A second conduit 42 and a third conduit 43 allow conveying air coming from the first conduits 41 to the third space 31. The second conduit 42 is housed in the interspace means at a lower portion of the containing means 2 and is connected to the third conduit 43. The latter is housed in the interspace means at side portions of the containing means and opens into the third space 31 through first outflow openings 52.

The second conduit means 44, 45, 46 is connected to the cooling chamber 15 through a plurality of second suction openings 53.

The second conduit means comprises a plurality of further first conduits 44, which are housed in the interspace means at side portions of the containing means 2 and open into the cooling chamber 15 through the second suction openings 53.

In the illustrated embodiment, the further first conduits 44 are six in total, arranged tree by three on opposite sides of the containing means 2; the further first conduits 44 are transversal, and in particular nearly orthogonal to the movement plane H. A further second conduit 45 and a further third conduit 46 allow conveying the air coming from the further first conduits 44 to the further third space 34. The further second conduit 45 is housed in the interspace means at an upper portion of the containing means 2 and it is connected to the further third conduit 46. The latter is housed in the interspace means at side portions of the containing means and opens into the further third space 34 through second outflow openings 52.

As highlighted in the Figures 7 and 8, the air emitted by the oriented jets F, exiting the deflecting means 19 of the diffusing elements 8 after skimming and cooling the products 100 arranged on the conveying means 3, is retrieved through the suction openings 51 , 53 and brought back to the fan means 4, 5 after being cooled and filtered. In the Figures 7 and 8 the white arrows indicate the air flow, heated and suctioned in the conduit means, the black arrows indicate the flow of cooled air exiting the heat exchanger means 6 and directed to the fan means 4, 5.

It is worth noting that, by virtue of the position and size of the suction openings 51 , 53 and the reduced width of the entry 1 1 and exit 12 openings, the emissions or dispersions of air from the apparatus 1 are minimal. In this manner, the retrieved air, partially heated by the products 100, since it is always maintained at a temperature less than that of the external environment in which the apparatus 1 is positioned, requires less energy for being cooled again to the ideal service temperature. The latter is in function of the physical- chemical characteristics of the product 100 to be cooled.

Therefore, the apparatus 1 of the invention allows obtaining a considerable saving on the energy consumptions compared to the known cooling apparatuses.

Furthermore, the air, since it is filtered by the filtering units 7 at each passage through the heat exchangers 6 and the fans 4, 5, keeps itself clean and substantially free from particles, dust, pollutants, which, once blown on the products, could compromise the quality of the successive decoration to be applied onto the product. Therefore, the apparatus of the invention allows obtaining a better quality of the application processes of the decorations, in particular of the serigraphic processes.

Claims

1. Cooling apparatus for cooling products (100), in particular semifinished tiles, comprising containing means (2) defining an internal volume provided with an entry opening (1 1 ) and with an exit opening (12) for said products (100) and comprising, contained inside said internal volume, conveying means (3) for supporting and moving said products (100) through said internal volume along a movement plane (H) and fan means (4, 5) for directing air to said products (100), said apparatus comprising a first portion (10), provided with said conveying means (3), and a second portion (20) connected to said first portion (10) so as to be movable between a closed position (C), wherein said first portion (10) and said second portion (20) are opposite and joined to enclose in said internal volume said conveying means (3), and an open position (B), wherein said first portion (10) and said second portion (20) are spaced apart to permit access to said conveying means (3) and/or to the products (100) positioned on the latter, said fan means (4, 5) being housed in said first portion (10) and/or in said second portion (20).

2. The apparatus according to claim 1 , wherein said second portion (20) is rotatably connected to said first portion (10) and rotatable around an axis between said closed position (C) and said open position (B) and vice versa.

3. The apparatus according to claim 1 or 2, comprising heat exchanger means (6) for cooling the air directed to said products (100) and diffusing means (8) interposed between said fan means (4, 5) and said conveying means (3) to intercept an air flow generated by said fan means (4, 5) and to create a plurality of air jets (F) directed towards said products (100).

4. The apparatus according to claim 3, wherein said fan means comprises first fan means (4) and second fan means (5) facing each other with respect to said movement plane (H), said diffusing means comprising two diffusing elements (8) interposed respectively between said movement plane (H) and said first fan means (4) and between said movement plane (H) and said second fan means (5).

5. The apparatus according to claim 4, wherein each diffusing element (8) is provided with slots (18) for the passage of said air flow, deflecting means (19) being provided and associated to each slot (18) for deviating and directing a corresponding air jet (F) to said products ( 100).

6. The apparatus according to claim 4 or 5, wherein said first portion (10) further comprises said first fan means (4), a respective diffusing element (8) and a respective cooling unit (6) of said heat exchanger means, and said second portion (20) comprises said second fan means (5), a respective diffusing element (8) and a respective cooling unit (6) of said heat exchanger means.

7. The apparatus according to any of the preceding claims, comprising filter means (7) for filtering the air sucked by said fan means (4, 5) and subsequently directed to said products ( 100).

8. The apparatus according to claim 7, as appended to claim 6, wherein said filter means comprise two filtering units (7), each of which is arranged next to a corresponding cooling unit (6), said filtering units (7) being housed respectively in said first portion (10) and in said second portion (20).

9. The apparatus according to any of the preceding claims, comprising conduit means (41 -46) for sucking air from said internal volume at said work plane (H) and conveying it to said fan means (4, 5).

10. The apparatus according to claim 9, wherein said conduit means comprises first conduit means (41 , 42, 43) and second conduit means (44, 45, 46) housed and contained respectively in said first portion ( 10) and in said second portion (20).

11. A cooling apparatus for cooling products ( 100), in particular semifinished tiles, comprising containing means (2) defining an internal volume provided with an entry opening ( 1 1 ) and with an exit opening ( 12) for said products ( 100) and comprising, contained inside said internal volume:

- conveying means (3) for supporting and moving said products ( 100) through said containing means (2) along a movement plane (H) from said entry opening ( 1 1 ) to said exit opening ( 12);

fan means (4, 5) for directing air to said products ( 100);

diffusing means (8) interposed between said fan means (4, 5) and said conveying means (3) to intercept an air flow generated by said fan means (4, 5) and to create a plurality of air jets (F) directed to said products (100).

12. The apparatus according to claim 1 1 , wherein said diffusing means (8) defines in said internal volume a cooling chamber ( 15) traversed by said conveying means (3) and by said air jets (F), said cooling chamber ( 15) communicating with an external environment by means of said entry opening ( 1 1 ) and said exit opening ( 12).

13. The apparatus according to claim 1 1 or 12, wherein said diffusing means comprises at least one diffusing element (8) facing said fan means (4, 5) and provided with a plurality of slots ( 18) for the passage of said air flow, deflecting means ( 19) being provided and associated to each slot ( 18) for deviating and directing a corresponding air jet (F) to said products ( 100).

14. The apparatus according to claim 13, wherein said deflecting means (19) is arranged for adjusting a passage section of the respective slot (18) and/or for deviating and orienting an air jet (F) exiting said slot (18).

15. The apparatus according to claim 14, wherein said deflecting means comprises an outlet port (19) that is shaped and connected to the respective slot (18).

16. The apparatus according to one of the claims 1 1 to 15, comprising heat exchanger means (6), contained inside said internal volume, for cooling the air directed to said products (100).

17. The apparatus according to one of the claims 1 1 to 16, comprising conduit means (41 -46) arranged for sucking air from said internal volume at said work plane (H) and conveying it to said fan means (4, 5).

18. The apparatus according to claim 17, wherein said containing means (2) comprise first wall means (21) defining said internal volume and second wall means (22) that is external and containing said first wall means (21 ), said first wall means (21 ) and said second wall means (22) forming interspace means that is suitable for housing said conduit means (41 -46).

19. The apparatus according to claim 17 or 18, comprising separating means (23, 24) fixed inside said containing means (2) and connected to said fan means (4, 5), said separating means (23, 24) and said containing means (2) making in said internal volume a plurality of spaces (29-34) connected to said conduit means (41 -46) and arranged for conveying air to the fan means (4, 5) and to a cooling chamber (15) defined by said diffusing means (8) and traversed by said conveying means (3) and by said air jets (F).

20. The apparatus according to claim 19, as claim 17 is appended to claim 16, wherein said exchanger means (6) is positioned in said spaces (29-34) at outflow openings

(52, 54) of said conduit means (41 -46).

21. The apparatus according to one of the claims 1 1 to 20, comprising filter means (7) for filtering the air sucked by said fan means (4, 5) and subsequently directed to said products ( 100) through said diffusing means (8).

22. The apparatus according to claim 21 , as appended to claim 16, wherein said filter means (7) is arranged adjacent to said heat exchanger means (6).

23. The apparatus according to one of the claims 1 1 to 22, wherein said fan means comprises first fan means (4) and second fan means (5) facing each other with respect to said movement plane (H), said diffusing means comprising two diffusing elements (8) interposed respectively between said movement plane (H) and said first fan means (4) and between said movement plane (H) and said second fan means (5), each diffusing element (8) being provided with slots (18) for the passage of said air flow, deflecting means (19) being provided and associated to each slot (18) for deviating and directing a corresponding air jet (F) to said products (100).