IT202100013730A1 - Machine for the production of snacks based on puffed cereals and the like - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

?Machine for making puffed cereal snacks and the like?,

DESCRIPTION TEXT

Technical field

The present invention relates to the technical sector of equipment for the food industry and is been developed with particular reference to machines for the production of snacks or ?snack? based on cereals or the like, essentially in the form of pods more? or less thick. The invention? susceptible of application for the production of snacks based on ?puffed? cereals? or ?exploded?, or ?puffed? or ?popped?, respectively, according to an Anglo-Saxon terminology used in the sector.

State of the art

Machines of the indicated type generally include heated presses, configured to compress and heat a dose of raw material, in order to obtain a pod. Depending on the type of press drive, the machine can? produce pods of different thicknesses: in the sector, the most? thick are usually referred to as? biscuits?, while those pi? as thin as a ?chip?, as similar to a potato chip.

The production of cereal biscuits, for example rice biscuits, provides that the cereal grains undergo a compression and heating phase, so as to expand considerably when the press is reopened: the biscuit will have then a low density? compared to the original grains, due to their volume expansion, and a certain thickness. The same machines can also be used for the production of chips: in this case? a second compression phase is usually provided, which follows the expansion of the product at the end of the first compression phase, substantially for the purpose of thinning the wafer and forming the chip.

The presses employed typically include die plates that are movable so that they can be moved towards and away from each other, and often also relative to a stationary die plate. The drive ? commonly carried out by means of hydraulic cylinders, or by pneumatic cylinders, or still by electric motors.

Hydraulically operated presses have the advantage of allowing relatively rapid drives: given that the fluidic circuit is closed, the relevant cylinders are able to react very quickly to the actuation commands. However, the hydraulic drive? intrinsically unsuitable for use in an environment where adequate hygienic conditions are required for the treatment of food products (think of possible phenomena of leakage and oozing from the cylinders). Presses operated pneumatically do not have the aforementioned problems, but have a basically open compressed gas supply circuit: for this reason, in order to allow for very rapid actuations, when necessary, special measures must be taken, such as the use of two cylinders in series to operate a single mold plate.

The machines according to the prior art have certain drawbacks.

The first drawbacks are related to the general conformation of the machine, the supporting structure of which generally provides for a base from which a columnar element rises, which supports the working unit, including the heated press. This type of structure implies that the work environment must be equipped with oversized cooking fumes and vapors extraction systems, and which often do not allow to avoid the dispersion of part of these fumes or vapors in the environment in the work environment itself . For the same reason, and as regards the aforementioned ?columnar? can be associated with a grilled accident-prevention protection system, in known machines any processing scraps or dust (such as crumbs, blown burrs, grains of unexploded cereals, etc.) are dispersed on the surrounding flooring, increasing the slipperiness? of the flooring itself and forcing the operators to frequently clean the workplace.

Other drawbacks are related to the industriousness? and the times required to prepare the machine differently in the event of changes in production batches or orders, or in the type of products to be obtained from the machine. These operations involve the replacement of a dosing plate, i.e. a member assigned to supply the press with the dose of cereal or similar necessary for the production of the product of interest. The activity replacement of this plate is generally relatively time-consuming and laborious.

Still other drawbacks are linked to the difficulty, in pneumatically operated machines, of regulating the expansion of the product to be obtained, if not by acting on the pressure of the compressed air. The air, however, is compressible and there? it generally complicates obtaining adequate and constant operating precision. Also by increasing the inlet pressure to the pneumatic cylinders, for example in order to obtain a greater expansion of the cereals subjected to cooking and compression, ? is it possible that you determine speed? different displacements between an upper mold plate and a lower mold plate, with the consequent risks of obtaining products that are different or in any case not expanded in a homogeneous manner.

Purpose and summary

In its general terms, the present invention proposes to realize a machine of the type indicated at the beginning which allows to solve one or more? of the aforementioned drawbacks.

In this context, a purpose of the invention? that of realizing a machine of the type indicated having a structure that allows to increase the salubrit? of the working environment. Another purpose of the invention ? that of realizing a machine of the type indicated in which the operations of change of production can take place in times more? faster and more easily? compared to known machines. A further purpose of the invention ? that of realizing such a machine, particularly pneumatically operated, in which a high displacement precision of one or more? mold plates, without necessarily having to act on the supply pressure of the pneumatic cylinders.

One or more? of the aforesaid aims, and still others that will become clear later, ? achieved or are achieved, according to the invention, by a machine having the characteristics indicated in the attached claims. The claims form an integral part of the technical teaching which ? provided herein in connection with the invention.

Brief description of the drawings

Further objects, characteristics and advantages of the invention will become apparent from the following description, made with reference to the annexed drawings, provided purely by way of non-limiting example, in which:

- figure 1 ? a schematic perspective view of a machine for producing snacks, according to possible embodiments;

- figures 2, 3 and 4 are schematic partial exploded views of the machine of figure 1;

- figure 4a ? a simplified sectional representation of a lower part of a machine according to possible embodiments;

- figure 5 ? a schematic side elevation of a unit? of working a machine for the production of snacks, according to possible embodiments;

- figure 6 ? a perspective view, partial and schematic, dell?unit? of working of figure 5, with some components removed;

- figure 7 ? a detail on a larger scale of figure 6;

- figure 8 ? a schematic side section aimed at exemplifying the principle diagram of a press of the unit? of machining of figures 4-5;

- figures 9a - 9k are schematic representations, similar to that of figure 8, intended to exemplify a possible working sequence of the press of figure 8; And

- figure 10 ? a schematic representation of a hydraulic scheme of principle for the operation of a unit? processing of the type exemplified in figure 5.

Description of preferred embodiments

Reference to an embodiment within this description indicates that a particular configuration, structure, or feature described in relation to the embodiment is included in at least one embodiment. So, phrases like ?in one embodiment?, ?in various embodiments? and the like, possibly present in various places of this description, do not necessarily refer to the same embodiment. Furthermore, particular shapes, structures or characteristics defined within this description can be combined in any suitable way in one or more? embodiments, even different from those shown. Numerical and spatial references (such as ?top?, ?bottom?, ?top?, ?bottom?, etc.) used herein are for convenience only. and therefore do not define the scope of protection or the scope of the forms of implementation. In the figures, the same reference numbers are used to indicate similar or technically equivalent elements. In the following the terms ?superior? and ?lower?, when referring to internal chambers with variable volume of the pneumatic cylinders described below, are intended to identify the chamber more? distant and more next, respectively, to a molding group.

Referring initially to figure 1, with 1 ? indicated as a whole a machine for the production of snacks based on cereals. Machine 1? suitable for the production of puffed or exploded cereal pods, in the form of biscuits or chips.

Referring also to figures 2-4, the machine 1 has a load-bearing structure which includes a frame indicated as a whole with 2, of substantially polyhedral shape, preferably substantially parallelepiped, formed by a plurality of of upright and transverse structural elements, later identified for simplicity? how ?uprights? and ?crossbars?, preferably of metallic material (for example stainless steel). In the example shown, four uprights 3 are provided, which are connected, at the relative ends, upper and lower, by means of four lower crosspieces 4 and four upper crosspieces 5. In various embodiments, the load-bearing structure represented by the frame 2 therefore includes a structural base (here formed by the lower crosspieces 4) and a top? structural (here formed by the upper crosspieces 5), which are connected to each other by means of a plurality? of structural uprights (represented here by uprights 3).

The load-bearing structure represented by frame 2, or its structural base, can be equipped with lower pivoting wheels W, in order to allow manual movement of the machine if necessary. Preferably, at least two of the wheels W are provided with brakes.

According to an important aspect, in various embodiments, the frame 2 includes an anchoring and support structure, in an intermediate position with respect to the aforementioned base and top? structural, for a machining group of the machine 1 preferably comprising two units? of independent machining, such as those indicated with indicated with 30 in the figures. Referring to the illustrated example, in various preferential embodiments, the uprights 3 are connected, in their intermediate region, by means of four intermediate load-bearing crosspieces 6, which form the aforementioned anchoring and support structure.

According to an important aspect, in various embodiments, at least the region of the frame 2 which extends between the upper crosspieces 4, or the top, and the crosspieces 6, or the intermediate anchoring and support structure, is shielded or peripherally closed by means of a series of casings or substantially closed upper panels, i.e. not having a grid shape, coupled in a removable way to the corresponding portions of the frame 2. In order to facilitate their removal, these upper panels can be provided with slits which act as handle. The upper panels are preferably of metallic material, for example stainless steel.

In the example four upper panels 10a-10d are therefore provided, of which the front one, indicated by 10a, ? preferably provided with an opening 11. At the opening, on the panel 10a ? a door 12 is mounted, preferably hinged at its upper edge, and provided with a handle, indicated with 12a only in figure 1. The door 12 is preferably provided with an inspection window, formed with a plate of transparent material, indicated with 12b only in figure 1. The height dimensions of the opening 11 of the panel 10a are greater than those of the door 12, so that from the lower part from the opening itself, not covered by the door 12, means for removing the pods protrude, represented here by two inclined chutes indicated by 30?, one for each unit? working area 30. The part of the opening 11 not covered by the door 12? however low in height.

The presence of the door 12 allows, through the window 12b, to visually check the operation? of the units? 30, and possibly access at least the mold plates of the units? 30, if minor interventions are required? (such as for example the removal of a jammed wafer or accumulations of burnt cereals in correspondence with a press of the units 30, or for the rapid cleaning of the internal surface of the window 12a). At counter 12 ? preferably associated with a safety sensor, such as a microswitch, arranged in the electrical circuit of the machine 1 in such a way that, if the door is opened, the operation of the machine is immediately interrupted. In case of maintenance interventions more? substantial of the machine ? Is it possible to proceed with the removal of one or more? panels 10a-10d from frame 2.

The fact that the panels 10a-10d are substantially closed, ie not in a grid, allows ? as well as fulfilling an accident prevention protection? to contain the fumes and/or cooking vapors which develop during operation of the machine 1. The panels 10a-10d in fact allow these fumes and/or vapors to be conveyed upwards, towards the end? top of the machine, or the top? structural, in correspondence of which pu? a hood, such as the one indicated by 20, provided with a fitting 20a for connection to an aspiration and/or evacuation system can be fitted.

According to an important aspect, in various embodiments, the region of the frame 2 which extends between the lower crosspieces 4, ie the structural base, and the intermediate anchoring and support structure, here formed by the crosspieces 6, is shielded or closed peripherally, by means of a series of casings or substantially closed lower panels, i.e. not having a grid shape, coupled in a removable way to the corresponding portions of the frame 2. In order to facilitate their removal, also these lower panels can be provided with slits which act as a handle. The lower panels are preferably of metallic material, for example stainless steel.

In the example three lower panels are shown, indicated by 13a, 13b and 13d, -13d, of which at least one - preferably the front one indicated by 13a -? can? be provided with a series of ventilation or suction openings 14, here in the form of slits. In the? example not ? shown a lower panel in the rear position (ie below the upper panel 10c), since? in that position? mounted an electric and pneumatic control panel, not shown; will you appreciate? however that a lower panel pu? be provided in place of the aforementioned control panel, if equipped with one or more? openings for the passage of at least one electrical supply cable and at least one pneumatic supply conduit.

The presence of the openings 14 allows adequate ventilation of the inside of the machine 1, which, as seen, is peripherally delimited by the aforementioned panels and by the aforementioned electrical panel. The openings 14 also allow, particularly in the presence of the hood 20, an adequate intake of air from outside, and therefore an internal air exchange; preferably, the relative position between the openings 14e and the fitting 20a of the hood 20? predisposed to induce a flow of air that invests the unit? 30, for ventilation purposes.

The fact that the panels 13a, 13b and 13d and the aforementioned electrical panel are substantially closed, i.e. not in the form of a grid, allows other than fulfilling an accident prevention protection? to contain inside the machine the scraps and/or cereal dust or the like which originate during the operation of the machine 1. The panels 13a, 13b and 13d and the internal side of the control panel in fact allow to convey downwards such scraps and/or dust, limiting their dispersion in the external environment.

According to an important aspect, in various preferential embodiments, particularly in the presence of the lower panels and/or of the control panel, in the lower part of the structure of the machine ? a collection drawer for the aforesaid scraps and/or dust is provided. Such a drawer ? indicated with 15 in figures 2-4.

For this purpose, sliding guides for the drawer 15 are preferably associated with the supporting structure represented by the frame 2, in order to allow easy extraction thereof, for the purpose of evacuating the scraps and/or dust. At least some of the guides provided ? such as those indicated with 16, can be associated with two of the lower crosspieces 5 parallel to each other.

In various preferential embodiments, deflector elements are provided inside the machine, aimed at conveying towards the inside of the drawer 15 that part of the scraps and/or dust which may come into contact with the internal side of the lower panels and of the switchgear of control, and that sliding on them for gravity? it could cause jams in the drawer itself; the aforementioned deflector elements are therefore mounted more? at the top of the drawer. In the non-limiting example shown, the aforementioned deflector elements are indicated by 17 in figures 2-4, and are each fixed between two uprights 3 different from those which laterally delimit the opening for the drawer 15. In essence, the deflector elements 17 they define a slide or inclined plane which extends approximately between the outer side and the inner side of the mast in question. The concept ? exemplified, in extremely schematic form in figure 4a, where the two deflector elements 17 are represented in correspondence with the lateral sides of the machine, or rather with the lower panels 13b and 13d, and where it is possible to understand how the presence of these elements allows to convey scraps and/or dust towards the inside of the drawer, avoiding the risk of deposits on the guides 16.

In the example drawer 15 ? openable/closed at the back of the machine, but there? it is not an essential feature. In the exemplified case, the control panel, or the eventual lower rear panel that replaces it, will be? naturally of reduced height compared to the other lower panels, in order to allow the housing and sliding of the drawer 15. a further crosspiece 52 should be provided, in an intermediate position between the crosspieces 5 and 6 which are located at the rear of the machine.

The panels 10a-10d and/or 13a, 13b and 13d are preferably of the non-transparent type.

Machine 1? equipped with a? unit? control unit, indicated with UC, which supervises the operation of the electric and pneumatic components of the machine. The unit control CU can? be implemented through a PLC equipped with a user interface, for example a touch screen type display, and with memory means which contain the operating software and the eventual saving of recipes.

In figures 5 and 6 ? shown with different views a? unit? working element 30 which, as will be seen, comprises actuator means, particularly pneumatic, which can be controlled to cause relative linear displacements between two or more? mold plates, particularly an upper mold plate, a lower mold plate and an intermediate mold plate, in order to compress a dose of cereal for the purpose of obtaining the product.

In various embodiments, the unit? 30 has a respective load-bearing structure, provided for fastening to the anchoring and support structure of the frame 2, i.e. the structure formed by the intermediate crosspieces 6, which ? configured in such a way that the group the unit? is suspended with respect to the anchoring and support structure. In preferential embodiments, this structure of the unit? 30 includes two lateral metal plates 31, in parallel positions, the ends of which they can be secured, for example by means of threaded members - between two opposite crosspieces 6. Respective pairs of rods or the like 32 rise from the two plates 31, which mutually support the structure of an upper compression cylinder 1001. From the structure of the cylinder 1001, rods or the like 33 in turn rise, which support the compression structure an upper handling or displacement cylinder 2001. The compression cylinder 1001 has a through rod 101, at the end of which? superior or proximal? rod 201 of the displacement cylinder 2001 is mechanically coupled. It should be noted that in figure 6 the representation of the upper displacement cylinder, as well as of a lower displacement cylinder hereinafter mentioned, ? omitted for the needs of more? clear representation.

To the side plates 31 ? associated below the structure of a double-acting lower compression cylinder 1002. Rods or the like 34 extend downwards from the cylinder structure 1002, which support the structure of a double-acting lower displacement cylinder 2002 between them. Also in this case the compression cylinder 1002 has a through rod 101, at the end of which? superior or proximal? is the rod 201 of the displacement cylinder 2002 mechanically coupled. As will be seen, each pneumatic displacement cylinder 2001 or 2002 ? controllable to cause a piston displacement of the corresponding pneumatic compression cylinder 1001 or 1002 between a retracted position and a forward position, and the pneumatic compression cylinder 1001 or 1002 ? controllable to exert a squeeze on a dose of cereal P after its plunger ? been brought into the said forward position.

As can be seen, the provision of the side plates 31 substantially allows the group 30 to be supported and suspended within the supporting structure of the machine.

The unit 30 comprises a dosing plate DP, which defines at least one through dosing opening, and which ? moveable between:

- a recessed position, in which the dosing opening receives a dose of grain from a grain feed system, and

- an advanced position, in which the dosing opening is? axially aligned with a through opening of an intermediate mold plate, described hereinafter, for positioning the dose of cereal therein.

In the example shown, each lateral plate 31 carries a respective vertical lateral bracket 35 at the top, so that guide means are supported between the two brackets 35, represented here by a guide plate 36, to guide the linear movement of a aforementioned plate dosage, indicated by DP (it should be noted that in figure 5, one of the two brackets 35 is shown in an exploded view, for reasons of clarity of the drawings). Between the two brackets 35 also preferably extends a cross member ? indicated with 37 in figure 6 ? for positioning and/or fastening a further controllable linear actuator 38, here a pneumatic cylinder (but could be an electric actuator), used to cause reciprocating linear displacements of the dosing plate DP between the retracted position and the forward position, with respect to the guide plate 36. The cylinder 38 ? preferably arranged below the metering plate DP, or rather the guide plate 36, substantially parallel thereto.

The cylinder 38 has a rod 38a, to which the metering plate DP is connected. constrained by a mechanical coupling.

In various particularly advantageous embodiments, the dosing plate DP ? of the replaceable type, particularly in order to vary the production batches, and the separable mechanical coupling between the rod 38a of the cylinder 38 and the metering plate DP ? obtained by means of a quick change device.

In various embodiments, the quick-change device comprises:

- a first quick-change element associated with the rod of the linear actuator, having at least one first passage,

- a second quick-change element associated with the dosing plate, having at least one second passage,

- a locking member having a pin portion which ? engageable in the at least one first passage and in the at least one second passage, for releasably constraining the first quick-change element and the second quick-change element.

Preferably, the blocking member further has an engagement portion which is? which can be engaged and disengaged elastically or by snapping with respect to one of the first quick-change element, the second quick-change element and the stem 38a of the linear actuator 38, to prevent unwanted slipping of the pin portion of the locking member from the at least a first pass and from at least one second pass. Preferably, the aforementioned portion of the commitment ? engageable and disengageable elastically or with a snap action with respect to following a stress on the locking member, such as to induce a rotation of the pin portion within the at least one first passage and the at least one second passage.

Referring also to figure 7 , in the example shown, the first quick-change element includes a generally fork-shaped element 40, preferably metallic. The fork element 40, preferably provided with a connecting portion 40a at the end? of the stem 38a, has two parallel arms 40b between which ? an engagement portion 41a of a preferably metallic bracket 41 which forms the second quick-change element can be received. Preferably the bracket 41 ? secured below a portion of the extremity? back DP1 of the plate DP, possibly a shaped portion. The arms 40b of the fork element 40 are provided with respective holes 41b1 aligned with each other, and the portion 41a of the bracket 41 ? likewise provided with a through opening 41a1. That 41a1 opening ? which can be aligned with the holes 40b1, so as to receive a pin portion 42a of a lock member 42, preferably metallic, which can be removed quickly. In the example, the member 42 has a portion 42b which extends in a radial direction with respect to the pin 42a and which ? configured, at? the extremity? distal, for the elastic or snap coupling with the fork element 40, particularly with its portion 40a. Pi? particularly, in the example the aforementioned connecting portion 40a has a substantially cylindrical shape and the end? distal of the portion 42b of the member 42 defines a sort of open collar 42c, ie substantially in the shape of a ?C?, which ? elastically or snap-engageable on the portion 40a. How can we understand, starting from the coupled condition, ? sufficient to urge the portion 42b of the member 42 in the direction of inducing a rotation of the pin portion 42a - within the holes 40b1 of the fork 40 and the opening 41a1 of the bracket 41? to get with there? the release of the collar portion 42c from the portion 40a of the fork element 40, and the consequent possibility? to remove the pin 42a from the aforementioned holes and opening. Conversely, in order to reposition the member 42, it is sufficient to insert the pin 42a between the holes of the fork 40 and the opening of the bracket 41, and then cause its rotation until the collar portion 42c engages elastically on the portion 40a of the element a fork 40. The coupling portion 42c of the member 42 could be configured to resiliently or snap-engage directly on the rod 38a of the cylinder 38.

The arrangement of the quick-change device could at most be different from the one shown, for example inverted (ie with the functions of the fork element associated with the plate DP and the functions of the bracket 41 associated with the stem 38a of the linear actuator 38).

From each plate 31 rises a further pair of rods or the like 45, for the support of an intermediate mold plate, or cooking plate, indicated with IP, which has a plurality of of through openings (two of which are partially visible in figure 6, not indicated), which act as molding females. The intermediate mold plate IP, in a fixed position, has a flat upper surface, on which? stackable, by sliding, a corresponding portion of the dosing plate DP which? provided with respective through openings, the latter being capable of being aligned with the through openings of the stationary plate IP.

With UP ? indicated an upper mold plate, bearing a plurality? of taps or punches M, having a peripheral profile corresponding to that of the through openings of the intermediate plate IP. With LP ? indicated a lower mold plate, also bearing a plurality? of punches M having a peripheral profile corresponding to that of the through openings of the intermediate plate IP. At least one of the upper plate UP, the lower plate LP and the intermediate plate IP has associated heating means. For example, the punches M of the two plates UP and LP are preferably heatable, and for this purpose are internally provided with electric resistances, preferably controlled by thermocouples. The IP intermediate plate can also possibly be equipped with electric heating elements. The aforementioned resistances have the function of heating the raw material necessary for the formation of the pods; the modalities? temperature control regardless of the purpose? of the present invention.

In the preferred example described below, the mold plates UP and LP are both displaceable with respect to the mold plate IP, but in other embodiments different drives can be provided, for example with one of the plates UP and LP which is? in a fixed position, while the IP plate and the other between the UP and LP plates can be moved.

The upper mold plates UP and lower LP are linearly movable, and for this purpose they are mechanically coupled at the ends? of the through rods 101 of the upper 1001 and lower 1002 compression cylinders, respectively. According to an important aspect, in various preferential embodiments, this mechanical coupling is of the adjustable type, in order to allow fine or precision adjustment of the operating position of at least one of the plates UP and LP, or of the related punches M relative to the through openings of the intermediate plate IP. In the exemplified case, the adjustment system comprises a part with male thread F defined or associated with the end? proximal of the stem 101 of the cylinder 1001 and/or 1002, on which ? adjustably engaged a nut screw bushing UP1 or LP1, used to secure the plate UP or LP, respectively, to the relative stem 101.

In various embodiments, such a regulation system can be provided between the rod 201 of one or both of the displacement cylinders 2001, 2002 and the rod of the corresponding compression cylinder 1001, 1002. As mentioned, this possibility? adjustment allows to precisely establish the position of the punches M with respect to the openings of the intermediate plate IP.

Preferably, in order to ensure the precision of the relative movement between the upper plate UP and the lower plate LP, vertical guide rods 46 are constrained to the former, slidingly coupled in corresponding through holes of the latter; ? an inverse arrangement is obviously possible (that is, with the rods 46 fixed to the plate LP and passing through holes in the plate UP).

Does the machine include a feed system, to feed grain doses to the unit? of processing. For this purpose, again in figures 5 and 6, with 47 ? a hopper which can be fed with the raw material is shown (the hopper 47 is shown in an exploded view in figure 5). Hopper 47 ? secured below the guide plate 36 and has respective outlets to which - in use - the openings of the dosing plate DP are axially aligned, when this is? brought by the relative cylinder 38 into a rearward operating position, as explained below.

All parts in contact with food are preferably made of stainless steel. Preferably, at least the parts of the molds intended for contact with the food material are coated with titanium.

In figure 8 ? represented in schematic form the molding press made by the UP, LP and IP plates, with the relative DP dosing plate. In this figure are highlighted, compared to what already? previously described, one of the through-dosing openings DH of the plate DP and one of the through-openings MC of the intermediate plate IP, these openings being instead not indicated (for representation purposes, in the following figures 9a-9k, which exemplify the realization of a rice cake).

Figure 9a exemplifies a production start, where the DP plate is in a retracted position, in order to receive a dose P of raw material, i.e. of rice, in its through opening. In the example the lower plate LP ? positioned (through the lower displacement cylinder 2002 previously described) so that the top? of the relative punch or male M, inserted in the relative through or female opening of the intermediate plate IP, is substantially flush with the upper surface of the guide plate 36, on which the plate DP slides, and therefore the dose P.

Figure 9b exemplifies the subsequent advancement of the plate DP (obtainable through the previously described cylinder 38), which brings the dose P in correspondence with the relative female of the intermediate plate IP, i.e. on the top? of the male M of the lower plate LP.

Figure 9c exemplifies the subsequent lowering of the lower plate LP (obtainable through the previously described lower displacement cylinder 2002), with the relative male M which carries with it? by gravity the dose P, within the female of the intermediate plate IP, at the same time freeing the relative through opening of the plate DP.

Figure 9d exemplifies the subsequent withdrawal of the plate DP (obtainable through the previously described cylinder 38), with the through opening of the latter which can receive a new Pn dose of rice.

Figure 9e exemplifies the subsequent lowering of the upper plate UP (obtainable via the previously described upper displacement cylinder 2001), so that the associated male M fits into the female of the intermediate plate IP in which the dose P is located.

Figure 9f exemplifies the subsequent raising of the lower plate LP (now obtainable via the previously described lower displacement cylinder 2002), so that the corresponding male M also fits into the female of the intermediate plate IP.

Figure 9g exemplifies the subsequent actuation of the previously described upper and lower pressing cylinders 1001 and 1002, by means of which the dose is strongly pressed, for the set cooking time.

Figure 9h exemplifies the subsequent lowering of the lower plate LP (obtainable now by means of the previously described lower displacement cylinder 2002), to obtain the expansion of the biscuit FP.

Figure 9i exemplifies the subsequent raising of the upper plate UP (now obtainable through the previously described upper displacement cylinder 2001), so that the relative male M releases the female of the intermediate plate IP, with the cracker FP now formed.

Figure 9j exemplifies the subsequent raising of the lower plate LP (now obtainable through the previously described lower displacement cylinder 2002), in order to reach a position corresponding to that of figure 9a: the male M then brings the wafer FP flush with the surface top of the IP intermediate plate.

Figure 9k exemplifies the subsequent advancement of the plate DP (obtainable through the previously described cylinder 38), which brings the new dose Pn in correspondence with the female of the intermediate plate IP, i.e. on the top of the male M of the lower plate LP, and at the same time pushes the wafer FP beyond the intermediate plate IP for the purpose of its evacuation (that is, to make it fall onto the relative chute 30? of figures 1-3).

The cycle described ? usable for example for the realization of cakes pi? thick. For the realization of biscuits pi? thin, for example during the phase referred to in figure 9g or 9h, pu? a further lowering of the upper mold plate UP can be produced, particularly by means of the upper compression cylinder 1001, in order to further compress the dose of raw material.

Possibly, for the production of crackers pi? thick, ? It is also possible to carry out the steps of figures 9h-9i in a single step, ie with the descent of the lower plate LP and the simultaneous raising of the upper plate UP. In order to be able to implement this modality? of processing the use of devices for regulating the flow of the compressed air from the outlet of the relative compression cylinder is particularly advantageous, which increase or decrease its speed? in such a way that the lower and upper males M emerge from the female at the same time.

The making of chips, instead of biscuits, takes place largely in the same way as? described above with reference to figures 9a-9k, but with the substantial difference that ? during the phase referred to in figure 9g ? the lower plate LP lowers, for a few milliseconds (approximately between 50 and 200 milliseconds), and rises again a series of times, for example three times, in order to reduce the expanding power of the cereal and at the same time give a wavy/irregular shape to the product . Therefore, for the purposes of this processing ? set a mold opening time parameter (LP plate descent) and three cooking time parameters (closed mold as in figure 9g), at the end of which the cooking cycle ends.

The cycle time depends on the type and quantity? of cereals used, but also on the temperature set and the degree of doneness required. In general terms, a work cycle at 245?C ? of about 8" using loose, whole or broken cereals. If cereal pellets are used, the cycle can drop between 5? and 7?, depending on the type of pellet used (in this case, the temperature must be reduced ).

Processable cereals from the group 30 described are for example whole maize, maize, brown rice, rice, spelt, wheat, barley, in loose form or in pellets.

In figure 10 ? schematically represented the pneumatic circuit of a machine according to possible preferential embodiments of the invention, which includes an upper circuit section UC and a lower circuit section LC, and where each section includes the respective compression cylinder 1001, 1002 and the respective displacement cylinder 2001, 2002.

To the piston 102 of each compression cylinder 1001, 1002 ? associated with the relative stem 101, at one?end? of which? coupled the respective upper mold plate UP or lower mold plate LP, respectively, in order to cooperate with the intermediate mold plate IP, as explained above. At the other end? of the rods 101 (ie the one that protrudes outside the cylinders 1001 and 1002 in the opposite position to the intermediate plate IP), ? mechanically coupled the? extremity? of the rod 201 of the respective displacement cylinder 2001 or 2002, associated in turn with the relative piston 202. The two chambers A and B of variable volume inside each compression cylinder 1001 and 1002 (i.e. the two chambers separated by the piston 102) are connected to each other by means of an EL air recovery duct. The two chambers A and B of the cylinders 1001 and 1002 are also connected, by means of the ducts indicated by SLb and SLa, respectively, to a first and a second way of a control valve arrangement 3Va1 and 3Va2 (a third way ? for the release of air in the environment); on each duct SLb ? a flow regulator device FR1 and FR2, respectively, is provided, the functions of which will be explained later.

As you will see, is the 3Va1 or 3Va2 control tube arrangement ? controllable for:

- allowing a flow of compressed gas between the first chamber A and the second chamber B of the compression cylinder 1001 or 1002 when the associated piston 102 is moved by the displacement cylinder 2001 or 2002 between the forward position and the retracted position, and

- allowing a vent of compressed gas from the first chamber A when the compression cylinder 1001 or 1002 has to exert a compression on a dose of cereal.

In the exemplified embodiment ? An AC source of compressed gas is provided, assumed herein to be air, such as a compressor. Two branches of the pneumatic circuit branch off from this source CA, indicated by L1 and L2, respectively for the upper circuit section UC and the lower circuit section LC.

During operation, the compressed air flowing in the branch L1 separates into two flows La1 and Lb1, in order to feed the cylinders 1001 and 2001: the flow Lb1 feeds the cylinder 2001 through a control valve arrangement 5Vb1 and two related ducts Lb1a and Lb1b, connected to the upper and lower chambers of the cylinder itself, respectively. The flow La1 directly feeds the upper chamber B of the cylinder 1001. Similarly, the compressed air flowing in the branch L2 separates into two flows La2 and Lb2, in order to feed the cylinders 1002 and 2002: the flow Lb2 feeds the cylinder 2002 through a valve arrangement 5Vb2 and two relative ducts Lb2a and Lb2b, connected to the upper and lower chambers of the cylinder itself, respectively. The flow La2 directly feeds the upper chamber B of the 1002 cylinder.

The aforementioned valve arrangements 3Va1, 3Va2, 5Vb1 and 5Vb2 are preferably fast acting electric control valves, most preferably solenoid operated, the operation of which is ? managed by? unit? CU control. In the figure, the tube arrangements 5Vb1 and 5Vb2 are represented for simplicity? like three-way valves, but in reality? they are preferably five-way valve arrangements, two of which are for the release of air into the environment. The valve arrangements 3Va1 and 3Va2 are preferably three-way valves, the third of which is for the release of air into the environment. In the following, for simplicity?, the valve arrangements will be indicated for simplicity? also as valves.

In the upper section UC, the compressed air from the 5Vb1 valve can? feeding - through a first way thereof and the duct Lb1a - the upper chamber of the displacement cylinder 2001, in order to cause the advancement of the piston 202, with the associated rod 201; at the same time, through the duct Lb1b and a second and third way of the valve 5Vb1, the relative air is released from the lower chamber of the cylinder 2001 into the environment. When ? Instead ? necessary to cause the rod 201 to move back, through the duct Lb1b and the second way of the valve 5Vb1, the compressed air is fed into the lower chamber of the cylinder 2001, and at the same time the air from the upper chamber is released into the environment, through the conduit Lb1a, the first way and a fourth way of the valve 5Vb1. The same operation occurs for the displacement cylinder 2002 in the lower section LC, via the valve 5Vb2 and the ducts Lb2a and Lb2b.

As mentioned, the air flow La1 directly feeds the upper chamber B of cylinder 1001, which ? therefore constantly kept under pressure. When ? It is necessary to push through the piston 102, or the stem 101, the third way of the valve 3Va1 is opened, in order to release into the environment - through the duct SLa - part of the air present in the chamber A. It should be noted that the quantity? of air released? modest, as the stroke required for the piston 102 ? minimal: as mentioned, the cylinders 1001 and 1002 substantially have the sole function of pressing the dose of cereal, while the movement of their piston ? in fact achieved through the 2001 and 2002 cylinders.

The withdrawal of the piston 102, or of the rod 101, ? achieved by means of cylinder 2001, actuated in retraction as described above: in this phase - the valve 3Va1 connects the ducts SLb and SLb together, without releasing any air. A similar functioning takes place in the lower section LC, through the air flow La2 which directly feeds the chamber B of the cylinder 1002, the control of which takes place through the valve 3Va2 and the ducts SLa and SLb.

Ultimately, therefore:

- through cylinders 2001 and 2002 ? it is possible to move the stems 101 of the cylinders 1001 and 1002 into the operating position, the upper chambers of which B are constantly supplied with compressed air (ie with the chambers A and B in equilibrium); during the displacement produced by the cylinder 2001 or 2002, the valve 3Va1 or 3Va2, respectively, connects the ducts SLa and SLb together, so that? between the two chambers A and B of the cylinder there? a displacement of air without release into the environment, also thanks to the EL duct;

- when the rods 101 of the cylinders 1001 and 1002 are in the respective operative position, by means of the above described control of the valves 3Va1 and 3Va2, respectively, ? it is possible to obtain the thrust force necessary to compress the dose of cereal, with a minimum release of air into the environment from chambers A;

- through cylinders 2001 and 2002 ? it is then possible to move the stems 101 of the cylinders 1001 and 1002 into the inoperative position; also in this case, in the displacement phase, the valves 3Va1 and 3Va2, respectively, connect the ducts SLa and SLb together, so that? between the two chambers A and B of the cylinder there? a displacement of air without release into the environment (in this phase the duct EL is not operative, in view of the presence of a relative shut-off device, as explained below).

The unit of control CU ? configured to control the valves 3Va1, 5Vb1, 3Va2 and 5Vb2 independently, so that? air pressure can be selectively applied to each of the cylinders 1001, 2001, 1002 and 2002.

The movement of each UP or LP plate during the mold opening and closing steps? then achieved by means of displacement cylinders 2001 or 2002 and the relative valves 5Vb1 or 5Vb2, respectively, as indicated above.

Thanks to the connection of the rods 201 of the cylinders 2001 and 2002 to the rods 102 of the cylinders 1001 and 1002 ? obtained the simple movement of the mold plates UP and LP relative to the intermediate mold plate IP, respectively. For this reason, the displacement cylinders 2001 and 2002 do not have to exert a considerable force, and can therefore be relatively small in size, and therefore rapid. When were the UP and LP plates positioned in correspondence with the IP plate? instead it is necessary to develop a significantly greater force, in order to obtain the desired compression of the raw material: for this reason, the cylinders 2001 and 2002 are preferably larger.

During the actuation of the displacement cylinders 2001 and 2002, the air is kept inside the compression cylinders 1001 and 1002, thanks to the EL and/or SLa-SLb ducts, which connect the relative internal chambers A and B to each other , or by recycling the air from one chamber to another during the displacements of the piston 102. As mentioned, for the purposes of the thrust required by each compression cylinder 1001 or 1002, the valve 3Va1 or 3Va2 ? allows a modest venting of air from chamber A. In the return phase of the piston 102, obtained by means of the corresponding displacement cylinder 2001 or 2002, however, no air venting occurs from chamber B, thanks to the ducts SLa, SLb and the valve 3Va1 or 3Va2.

According to an important characteristic, downstream of the valves 3Va1 and/or 3Va2, on the respective duct SLb connected to the upper chamber B of the compression cylinder 1001 or 1002, ? an air flow regulator device FR1 and FR2 is provided. This device, for example represented by a faucet or the like, is configured or operable to allow for regulating or choking the flow of compressed gas between the first chamber A and the second chamber B as the second piston 102 is moved by the shift cylinder 1001 or 1002 between the forward position to the retracted position. The setting of the FR1 or FR2 device can? take place manually or in a servo-assisted way (through a suitable electric actuator) according to the type of product to be obtained. The flux regulation operable via the FR1 or FR2 devices allows in particular to control the speed? of withdrawal of the relative cylinder 1001 or 1002, and therefore the expansion and texture of the product to be obtained.

According to an important characteristic, in combination with the use of the flow regulator device FR1 and/or FR2, on the recovery duct EL ? provided for an interception organ, capable of:

- allowing the passage of compressed gas from the first chamber A to the second chamber B when the piston 102 of the compression cylinder 1001 or 1002 is moved by the relative displacement cylinder 2001 or 2002 from the retracted position to the forward position, and

- preventing the passage of compressed gas from the second chamber B to the first chamber A when the same piston 102 is moved by the displacement cylinder 2001 or 2002 from the advanced position to the retracted position.

In other words, therefore, the aforementioned interception body ? arranged to render the conduit EL inoperative during the retraction of the piston 102 of the piston 1001 or 1002.

In preferential embodiments, the aforesaid shut-off member comprises a non-return valve, such as those indicated by CV1 and CV2, respectively, in figure 10. In possible embodiment variants, the non-return valves could be replaced by respective solenoid valves, controlled by the unit CU to close the duct EL during the retraction of the piston 102 of the piston 1001 or 1002.

How to ? seen, the duct EP allows, during the advancement phase of the piston 102 of the compression cylinder 1001 or 1002 (caused by the corresponding displacement cylinder 2001 or 2002), the recovery of the compressed air contained in the chamber A (or the chamber closest to to the relative mold plate UP or LP) with a speed? of constant and high displacement of the same plunger. Conversely, during the retraction phase of the piston 102 (also caused by the corresponding displacement cylinder 2001 or 2002) the provision of the non-return valve CV1 or CV2 (or of any solenoid valve) prevents the air from chamber A to chamber B transits in the relative duct EL, with a consequent rapid withdrawal of the piston 102, and therefore of the mold plate UP or LP, which would have negative effects on the expansion and texture of the product, or on its quality.

In fact, during the retraction of the piston 102, the presence of the valve CV1 or CV2 has the effect of forcing the passage of air from chamber B to chamber A through the duct SLb, the regulator device FR1 or FR2, the valve 3Va1 or 3Va2 and the SLa duct: in this phase the device FR1 or FR2 therefore comes into play, the regulation of which allows you to slow down more? or not the withdrawal of the piston 102, and therefore the corresponding displacement of the mold plates UP and LP, for the purpose of obtaining the desired quality? of the product.

From the description given, the characteristics of the present invention are clear, so how clear are its advantages.

The particular construction of the supporting structure of the machine, characterized by uprights and crosspieces, allows to avoid the use of a base with a single columnar support element, typical of the prior art. In this way, the machining group of the machine can? be mounted in a substantially suspended condition inside in a central position of the supporting structure, with the latter which can? be easily peripherally equipped with panels, suitable for containing the dispersion of fumes and/or vapours, as well as? of scraps and/or processing dust. The structure described also allows the machine to be equipped with its own dedicated hood, which allows efficient evacuation of the fumes and/or vapors even with limited suction power (ie the hood must not be oversized). Does the structure also allow? to provide the aforementioned collection drawer, in which the processing scraps and/or dust can accumulate by gravity, without dispersions, keeping the work environment clean.

The provision of a quick-change device associated with the dosing plates of the machining group of the machine allows the replacement of this plate in an extremely simple and rapid way, with significant savings during production changes. The advantage ? especially important in manufacturing plants where many machines are in operation.

The possibility? to adjust in a simple but extremely precise way the mechanical coupling between the stems of the compression cylinders and the corresponding mold plates allows to obtain a high precision of molding of the snacks. Similar considerations apply in relation to the possibility adjustment of the mechanical coupling between the rods of the displacement cylinders and the rods of the compression cylinders.

The provision of the flow regulation devices FR1, FR2, in combination with the shut-off devices CV1, CV2 operating on the EL ducts allows you to set the speed easily but precisely. of withdrawal of the pistons of the compression cylinders, and therefore of the corresponding mold plates, and therefore control the expansion of the product, without the necessity? of having to intervene on the supply pressure of the cylinders. The possibility? adjustment allows you to prevent the compression cylinders backwards with speed? different, and therefore avoid the risk of obtaining different or non-homogenously expanded products.

AND? clear that numerous variants are possible for the person skilled in the art to the devices and methods described as an example, without thereby departing from the scope of the invention as as defined by the appended claims. Individual features described with reference to previously described embodiments can be combined with each other in other embodiments.

Preferential characteristics of the machine described are summarized in the following points:

1. A machine for the preparation of snacks based on puffed cereals and the like, having a bearing structure (2) and a working unit which includes at least one unit? processing unit (30) and a feeding system (47, DP), for feeding doses of cereal (P, Pn) to the unit? processing (30),

in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), an intermediate die plate (IP), defining at least one through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable,

in which the? unit? (30) further comprises actuator means (1001, 2001, 1002, 2002) controllable to cause relative linear displacements between the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP ), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M),

wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein the supporting structure (2) includes a plurality of of upright structural elements (3) connected in their lower region through a plurality? of lower transverse structural elements (5) and connected in their upper region through a plurality? of upper transverse structural elements (4),

wherein the upright structural elements (3) are also connected, in an intermediate region thereof, by means of a plurality of intermediate transversal structural elements (6), which create an anchoring and support structure,

wherein the processing unit (30) has a respective bearing structure (31-34) which ? fixed to the anchoring and support structure and ? configured in such a way that the machining group (30) is suspended with respect to the anchoring and support structure,

and in which the supporting structure (2) ? associated with a plurality? of substantially closed peripheral panels (10, 13), in correspondence with at least one of:

- a lower area, substantially included between the lower transverse structural elements (5) and the intermediate transverse structural elements (6),

- an upper area, substantially included between the upper transverse structural elements (5) and the intermediate transverse structural elements (6).

2. The machine as in point 1, in which the plurality? of peripheral panels (10, 13) comprises upper panels (10) in correspondence with said upper zone, the upper panels (10) being able to contain the dispersion of fumes and/or cooking vapors which develop during operation of the group of processing (30).

3. The machine as in point 2, further comprising an upper hood (20) provided with a fitting (20a) for connection to an aspiration and/or evacuation system, the upper panels (10) being able to convey the fumes and /o cooking vapors towards the upper hood (20).

4. The machine as any of the points 1-3, in which the plurality? of peripheral panels (10, 13) comprises lower panels (10) in correspondence with said lower area, the lower panels (10) being able to contain the dispersion of scraps and/or cereal powders produced during operation of the processing group ( 30).

5. The machine as in point 4, further comprising a lower collection drawer (15), for accumulating the scraps and/or cereal powders.

6. The machine as in point 5, in which at least two sliding guides (16) of the collection drawer (15) are associated with the supporting structure (2) of the machine (1).

7. The machine as in point 5, in which the bearing structure (2) is associated with deflector elements (17), configured to convey the scraps and/or cereal dust towards the inside of the collection drawer (15), each element deflector (17) defining a slide or an inclined plane and being mounted more? at the top of the collection drawer (15).

8. The machine as in any of the points 1-7, in which the plurality? of peripheral panels (10, 13) comprises at least one lower panel (13) in correspondence with said lower zone and provided with ventilation and/or suction openings (14).

9. The machine as in any of the points 1-8, in which the plurality? of peripheral panels (10, 13) comprises at least one upper panel (10) in correspondence with said upper zone and having an access opening (11) in correspondence with which ? mounted a door (12) having a transparent inspection window (12b), where preferably the access opening (11) has a height dimension greater than the door (12), so that from a lower area of the opening access (11) not covered by the door (12) protrude evacuation means (30?) of the snacks produced by the unit? processing (30).

10. The machine as in any one of the points 1-9, in which the supporting structure (2) is associated with a plurality lower wheels (W), at least some of which are preferably equipped with brakes.

11. A machine for the preparation of snacks based on puffed cereals and the like, having a bearing structure (2) and a processing unit which includes at least one unit processing unit (30) and a feeding system (47), to feed a cereal to the unit? processing (30),

in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), an intermediate die plate (IP), defining at least a first through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable,

in which the? unit? (30) further comprises first actuator means (1001, 2001, 1002, 2002) controllable to cause relative linear displacements between the upper die plate (UP), the lower die plate (LP) and the intermediate die plate ( IP), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M),

wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein the unit? (30) further comprises a dosing plate (DP), defining at least one second through opening (DH), the dosing plate (DP) being movable between:

- a retracted position, in which the second through opening (DH) receives a dose of cereal (P, Pn) from the feeding system (47), and

- an advanced position, in which the second through opening (DH) ? axially aligned with the first through opening (MC) of the intermediate mold plate (IP), to place the dose of cereal (P),

in which the? unit? (30) further comprises controllable second actuator means for causing reciprocating linear displacements of the metering plate (DP) between the retracted position and the forward position,

wherein the second actuating means (38) comprises a linear actuator (38) having a stem (38a) to which the metering plate (DP) is connected. connected via a mechanical coupling device,

in which the dosing plate (DP) ? of the replaceable type, particularly to allow the variation of production batches, and the mechanical coupling device comprises a quick-change device (40, 41, 42).

12. The machine as in point 11, wherein the quick change device (40, 41, 42) comprises:

- a first quick-change element (40) associated with the stem (38a) of the linear actuator (38) and having at least one first passage (40b1),

- a second quick change element (41) associated with the dosing plate (DP) and having at least one second passage (41a1),

- a locking member (42) having a pin portion (42a) engageable in the at least one first passage (40b1) and in the at least one second passage (41a1), to constrain the first quick change element (40b) in a detachable way ) and the second quick-change element (41),

wherein preferably the blocking member (42) further has a coupling portion (42c) which ? which can be engaged and disengaged elastically or by snapping with respect to one of the first quick-change element (40), the second quick-change element (41) and the stem (38a) of the linear actuator (38), to prevent unwanted slipping off of the portion pin (42a) of the locking member (42) from the at least one first passage (40b1) and from the at least one second passage (41a1).

13. The machine as in point 12, in which a coupling portion (42c) of the locking member (42) is? which can be engaged and disengaged elastically or by snapping with respect to one of the first quick-change element (40), the second quick-change element (41) and the stem (38a) of the linear actuator (38) following a stress on the member lock (42) such as to induce a rotation of the pin portion (42a) within the at least one first passage (40b1) and the at least one second passage (41a1).

14. The machine as in point 12, where:

- the first quick-change element (40) comprises a fork element (40), particularly associated with the stem (38a) of the linear actuator (38), having two parallel arms (40b), the at least one first passage (40b1 ) comprising mutually aligned holes of the two parallel arms (40b),

- the second quick-change element (41) comprises a bracket (41), particularly associated with the metering plate (DP), having an engagement portion (41a) receivable between the two parallel arms (40b) of the fork element ( 40a), the at least one second passage (41a1) comprising an opening of the engagement portion (41a) which ? likely to be aligned with said holes,

in such a way that between said holes and the opening ? the pin portion (42a) of the locking member (42) is admissible.

15. The machine as in point 12 and in point 13, in which the fork element (40) has a connection portion (40a) for connection at one end? proximal shaft (38a) of the linear actuator (38), and the coupling portion (42c) of the locking member (42) ? configured for elastic or snap engagement with respect to said connecting portion (40a).

16. The machine as in point 15, in which the connecting portion (40a) of the fork element (40) has at least partly a cylindrical shape and the coupling portion (42c) of the blocking member (42) ? basically shaped like C.

17. The machine as at any of points 11-16, where the linear actuator (38) is? a pneumatic cylinder or an electric actuator.

18. The machine as in point 14, where the bracket (41) ? secured below a portion of the extremity? back (DP1) of the dosing plate (DP).

19. The machine as in point 18, where the linear actuator (38) is? arranged below the dosing plate (DP), substantially parallel to it.

20. The machine as at any of the points 11-19, in which the unit? of processing (30) includes guide means (36), preferably comprising a guide plate (36), to which the metering plate (DP) is connected. slidably coupled to be moved between said rearward and forward positions.

21. A machine for the preparation of snacks based on puffed cereals and the like, having a bearing structure (2) and a processing unit which includes at least one unit? processing unit (30) and a feeding system (47, DP), for feeding doses of cereal (P, Pn) to the unit? processing (30),

in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), and an intermediate die plate (IP) defining at least one through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable,

in which the? unit? (30) has an actuation system comprising a source of compressed gas (CA) and pneumatic actuator means (1001, 2001, 1002, 2002), controllable to cause relative linear displacements between the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M),

wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein, for at least one of the upper mold plate ( UP) and the lower mold plate (LP), the pneumatic actuator means (1001, 2001, 1002, 2002), include:

- a pneumatic displacement cylinder (2001, 2002) having a first piston (202) connected to a first rod (201), and

- a pneumatic compression cylinder (1001, 1002), having a second piston (102) connected to a second through rod (101), in which the first rod (201) has one end? distal connected to one end? proximal of the second through stem (101), at one end? distal of the second through stem (101) being connected the upper mold plate (UP) or the lower mold plate (LP), respectively,

in which the pneumatic displacement cylinder (2001, 2002) ? controllable to cause the second piston (102) of the pneumatic compression cylinder (1001, 1002) to move between a retracted and a forward position,

in which the pneumatic compression cylinder (1001, 1002) ? controllable to exert a compression on a dose of cereal (P) after the second plunger (102) ? been brought to the said forward position,

wherein the second piston (102) delimits in the pneumatic compression cylinder (1001, 1002) a first chamber of variable volume (A), more? next to the upper mold plate (UP), respectively to the lower mold plate (LP), and a second chamber of variable volume (B), smaller? away from the upper mold plate (UP), respectively from the lower mold plate (LP),

in which the second chamber (B) ? connected in fluid communication with the compressed gas source (CA) via a first pipe (L1, La1),

in which the first chamber (A) ? selectively connectable to the second chamber (B) via a second duct (SLa, SLb) on which ? operatively arranged a respective control valve arrangement (3Va1, 3Va2),

in which the first chamber (A) ? also connected to the second chamber (B) via a third duct (EL),

in which the control valve arrangement (3Va1, 3Va2) ? controllable for:

- allowing a flow of compressed gas between the first chamber (A) and the second chamber (B) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) between the forward position and the retracted position, and

- allow a vent of compressed gas from the first chamber (A) when the pneumatic compression cylinder (1001, 1002) must exert a compression on a dose of cereal (P),

where on the second duct (SLa, SLb) ? further operatively arranged is a flow regulator device (FR1, FR2), configured to regulate or choke the flow of compressed gas between the first chamber (A) and the second chamber when the second piston (102) is moved by the pneumatic displacement cylinder ( 2001, 2002) between the forward position and the backward position,

in which on the third duct (EL) ? operationally arranged an interceptor device (CV1, CV2) capable of:

- allowing the passage of compressed gas from the first chamber (A) to the second chamber (B) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) from the retracted position to the forward position, and

- preventing the passage of compressed gas from the second chamber (B) to the first chamber (A) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) from the forward position to the retracted position,

22. The machine as in point 21, in which the shut-off device (CV1, CV2) includes a non-return valve.

23. The machine as in item 21 or 22, wherein the control valve arrangement (3Va1, 3Va2) includes an electric three-way valve.

24. The machine according to any of the points 21-23, further comprising a further control valve arrangement (5Vb1, 5Vb2) for the control of the pneumatic displacement cylinder (2001, 2002), the further control valve arrangement (5Vb1, 5Vb2 ) being operatively disposed between the compressed gas supply source (CA) and the pneumatic displacement cylinder (2001, 2002).

25. The machine as in point 24, where:

- the first piston (202) delimits in the pneumatic displacement cylinder (2001, 2002) a respective first chamber of variable volume, more? next to the upper mold plate (UP), respectively to the lower mold plate (LP), and a respective second chamber of variable volume, larger? away from the upper mold plate (UP), respectively from the lower mold plate (LP),

- the further control valve arrangement (5Vb1, 5Vb2) includes a three-five-way electric valve, controllable for:

- connecting the compressed gas supply source to said respective second chamber and at the same time allowing a vent of compressed gas from said respective first chamber, when the first piston (202) is moved from a respective retracted position to a respective advanced position, and

- connecting the compressed gas supply source to said respective first chamber and at the same time allowing a vent of compressed gas from said respective second chamber, when the first piston (202) is moved from the respective advanced position to the respective retracted position.

26. The machine as in any of the points 21-25, in which the? distal of first stem (202) ? connected mechanically in an adjustable way to the? extremity? proximal of the second through stem (101).

27. The machine as in any of the points 21-26, in which the? proximal of the second through stem (101) ? adjustably mechanically connected to the upper mold plate (UP), respectively to the lower mold plate (LP).

28. The machine as in any of the points 21-27, in which the flow regulator device (FR1, FR2) ? a device that can be operated manually or in a servo-assisted manner, by means of an electric actuator.

29. The machine as at any of the points 21-28, wherein the pneumatic actuating means (1001, 2001, 1002, 2002) of the upper mold plate (UP) and the lower mold plate (LP), each comprise a said displacement pneumatic cylinder (2001, 2002), said compression pneumatic cylinder (1001, 1002), said first duct (L1, La1), said second duct (SLa, SLb) with respective control valve arrangement (3Va1 , 3Va2) and flow regulator device (FR1, FR2), a said third duct (EL) with respective shut-off member (CV1, CV2).

Claims (11)

1. A machine for the preparation of snacks based on puffed cereals and the like, having a bearing structure (2) and a working unit which includes at least one unit? processing unit (30) and a feeding system (47, DP), for feeding doses of cereal (P, Pn) to the unit? processing (30), in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), and an intermediate die plate (IP) defining at least one through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable, in which the? unit? (30) has an actuation system comprising a source of compressed gas (CA) and pneumatic actuator means (1001, 2001, 1002, 2002), controllable to cause relative linear displacements between the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M), wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein, for at least one of the upper mold plate ( UP) and the lower mold plate (LP), the pneumatic actuator means (1001, 2001, 1002, 2002), include: - a pneumatic displacement cylinder (2001, 2002) having a first piston (202) connected to a first rod (201), and - a pneumatic compression cylinder (1001, 1002), having a second piston (102) connected to a second through rod (101), in which the first stem (201) has an extremity? distal connected to one end? proximal of the second through stem (101), at one end? distal of the second through stem (101) being connected the upper mold plate (UP) or the lower mold plate (LP), respectively, in which the pneumatic displacement cylinder (2001, 2002) ? controllable to cause the second piston (102) of the pneumatic compression cylinder (1001, 1002) to move between a retracted and a forward position, in which the pneumatic compression cylinder (1001, 1002) ? controllable to exert a compression on a dose of cereal (P) after the second plunger (102) ? been brought to the said forward position, wherein the second piston (102) delimits in the pneumatic compression cylinder (1001, 1002) a first chamber of variable volume (A), more? next to the upper mold plate (UP), respectively to the lower mold plate (LP), and a second chamber of variable volume (B), smaller? away from the upper mold plate (UP), respectively from the lower mold plate (LP), in which the second chamber (B) ? connected in fluid communication with the compressed gas source (CA) via a first pipe (L1, La1), in which the first chamber (A) ? selectively connectable to the second chamber (B) via a second duct (SLa, SLb) on which ? operatively arranged a respective control valve arrangement (3Va1, 3Va2), in which the first chamber (A) ? also connected to the second chamber (B) via a third duct (EL), in which the control valve arrangement (3Va1, 3Va2) ? controllable for: - allowing a flow of compressed gas between the first chamber (A) and the second chamber (B) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) between the forward position and the retracted position, and - allow a vent of compressed gas from the first chamber (A) when the pneumatic compression cylinder (1001, 1002) must exert a compression on a dose of cereal (P), where on the second duct (SLa, SLb) ? further operatively arranged is a flow regulator device (FR1, FR2), configured to regulate or choke the flow of compressed gas between the first chamber (A) and the second chamber when the second piston (102) is moved by the pneumatic displacement cylinder ( 2001, 2002) between the forward position and the backward position, in which on the third duct (EL) ? operationally arranged an interceptor device (CV1, CV2) capable of: - allowing the passage of compressed gas from the first chamber (A) to the second chamber (B) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) from the retracted position to the forward position, and - preventing the passage of compressed gas from the second chamber (B) to the first chamber (A) when the second piston (102) is moved by the pneumatic displacement cylinder (2001, 2002) from the forward position to the retracted position. 2. The machine according to claim 1, wherein the shut-off member (CV1, CV2) comprises a non-return valve. The machine according to claim 1 or claim 2, wherein the control valve arrangement (3Va1, 3Va2) comprises an electric three-way valve. The machine according to any one of claims 1-3, further comprising a further control valve arrangement (5Vb1, 5Vb2) for controlling the pneumatic displacement cylinder (2001, 2002), the further control valve arrangement (5Vb1, 5Vb2 ) being operatively disposed between the compressed gas supply source (CA) and the pneumatic displacement cylinder (2001, 2002). 5. The machine according to claim 4, wherein: - the first piston (202) delimits in the pneumatic displacement cylinder (2001, 2002) a respective first chamber of variable volume, more? next to the upper mold plate (UP), respectively to the lower mold plate (LP), and a respective second chamber of variable volume, larger? away from the upper mold plate (UP), respectively from the lower mold plate (LP), - the further control valve arrangement (5Vb1, 5Vb2) includes a three-five-way electric valve, controllable for: - connecting the compressed gas supply source to said respective second chamber and at the same time allowing a vent of compressed gas from said respective first chamber, when the first piston (202) is moved from a respective retracted position to a respective advanced position, and - connecting the compressed gas supply source to said respective first chamber and at the same time allowing a vent of compressed gas from said respective second chamber, when the first piston (202) is moved from the respective advanced position to the respective retracted position. 6. The machine according to any one of claims 1-5, in which the end? distal of first stem (202) ? connected mechanically in an adjustable way to the? extremity? proximal of the second through stem (101). 7. The machine according to any one of claims 1-6, in which the end? proximal of the second through stem (101) ? adjustably mechanically connected to the upper mold plate (UP), respectively to the lower mold plate (LP). 8. The machine according to any one of claims 1-7, wherein the flow regulator device (FR1, FR2) is ? a device that can be operated manually or in a servo-assisted manner, by means of an electric actuator. 9. The machine according to any one of claims 1-8, wherein the pneumatic actuator means (1001, 2001, 1002, 2002) of the upper mold plate (UP) and of the lower mold plate (LP), each comprise a said displacement pneumatic cylinder (2001, 2002), a said compression pneumatic cylinder (1001, 1002), a said first duct (L1, La1), a said second duct (SLa, SLb) with respective control valve arrangement (3Va1, 3Va2) and flow regulator device (FR1, FR2), a said third duct (EL) with respective shut-off device (CV1, CV2). 10. A machine for the preparation of snacks based on puffed cereals and the like, having a supporting structure (2) and a working unit which includes at least one unit processing unit (30) and a feeding system (47, DP), for feeding doses of cereal (P, Pn) to the unit? processing (30), in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), an intermediate die plate (IP), defining at least one through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable, in which the? unit? (30) further comprises actuator means (1001, 2001, 1002, 2002) controllable to cause relative linear displacements between the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP ), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M), wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein the supporting structure (2) includes a plurality of of upright structural elements (3) connected in their lower region through a plurality? of lower transverse structural elements (5) and connected in their upper region through a plurality? of upper transverse structural elements (4), wherein the upright structural elements (3) are also connected, in an intermediate region thereof, by means of a plurality of intermediate transversal structural elements (6), which create an anchoring and support structure, wherein the processing unit (30) has a respective supporting structure (31-34) which ? fixed to the anchoring and support structure and ? configured in such a way that the machining group (30) is suspended with respect to the anchoring and support structure, and in which the supporting structure (2) ? associated with a plurality? of substantially closed peripheral panels (10, 13), in correspondence with at least one of: - a lower area, substantially included between the lower transverse structural elements (5) and the intermediate transverse structural elements (6), - an upper area, substantially included between the upper transverse structural elements (5) and the intermediate transverse structural elements (6). 11. A machine for the preparation of snacks based on puffed cereals and the like, having a bearing structure (2) and a processing unit which includes at least one unit processing unit (30) and a feeding system (47), to feed a cereal to the unit? processing (30), in which the? unit? (30) comprises an upper die plate (UP) with at least one upper punch (M), a lower die plate (LP) with at least one lower punch (M), an intermediate die plate (IP), defining at least a first through opening (MC) in which the upper punch (M) and the lower punch (M) are at least partially receivable, in which the? unit? (30) further comprises first actuator means (1001, 2001, 1002, 2002) controllable to cause relative linear displacements between the upper die plate (UP), the lower die plate (LP) and the intermediate die plate ( IP), in order to compress a dose of cereal (P) between the upper punch (M) and the lower punch (M), wherein at least one of the upper mold plate (UP), the lower mold plate (LP) and the intermediate mold plate (IP) has associated heating means, wherein the unit? (30) further comprises a dosing plate (DP), defining at least one second through opening (DH), the dosing plate (DP) being movable between: - a retracted position, in which the second through opening (DH) receives a dose of cereal (P, Pn) from the feeding system (47), and - an advanced position, in which the second through opening (DH) ? axially aligned with the first through opening (MC) of the intermediate mold plate (IP), to place the dose of cereal (P), in which the? unit? (30) further comprises controllable second actuator means for causing reciprocating linear displacements of the metering plate (DP) between the retracted position and the forward position, wherein the second actuating means (38) comprises a linear actuator (38) having a stem (38a) to which the metering plate (DP) is connected. connected via a mechanical coupling device, in which the dosing plate (DP) ? of the replaceable type, particularly to allow the variation of production batches, and the mechanical coupling device comprises a quick-change device (40, 41, 42).