WO2015032908A1

WO2015032908A1 - Method and apparatus for simultaneously foaming two or more objects

Info

Publication number: WO2015032908A1
Application number: PCT/EP2014/068962
Authority: WO
Inventors: Marco VOLPATO; Maurizio Corti; Claudio De Rossi
Original assignee: Cannon S.P.A.
Priority date: 2013-09-06
Filing date: 2014-09-05
Publication date: 2015-03-12
Also published as: ITMI20131471A1

Abstract

A method (and corresponding apparatus) for simultaneously foaming two objects or two or more pairs of objects (2, 2a, 2b) each having two prevalent dimensions compared with a third dimension and being provided with two outer coating elements (3, 3i, 3e, 3i', 3e') of the shell type or of the flat, curved or thermoformed slab or sheet type in order to compose the elements into a box element, for example for forming a refrigerator door between said two outer coating elements (3, 3i, 3e, 3i', 3e') there being interposed an intermediate layer (4) made of expanded polyurethane or phenolic thermally insulating material (for example a foam) comprises the steps of: i). inserting the two coating elements (3i, 3e) of a first object (2a) inside a first containing unit (5a), and the two coating elements (3i', 3e') of a second object (2b) inside a second containing unit (5b); ii). moving the first (5a) and second (5b) containing unit against possible respective counter-template separating baffles 12 aand 12b to close, in the forming position and the required geometric shape required, the hollow box elements and in such a manner as to define a single foaming operative module (10) containing two or more objects or pairs of objects (2, 2a, 2b) to be foamed simultaneously, in which, inside said foaming operative module (10), the coating elements (3, 3i, 3e, 3i', 3e') of the first object (2a) and of the second object (2b), are arranged according to respective mutually parallel planes, and a coating element (3i) of said first object (2a) and a respective coating element (3i') of said second object (2b) are near to one another in a mutually facing position, separated possibly only by the respective separating baffles having a counter-template function; iii). hooking the foaming operative module (10) on a rotatable storage structure (6) that is provided with hooking and clamping means (11) and housing means (7) for each foaming operative module (10); iv). simultaneously dispensing distinct flows of polyurethaneor phenolic mixture each inside a respective object (2, 2a, 2b) to be foamed; v). enabling the coating element (3i) of the first object (2a) and the coating element (3i') of the second object (2b) that are placed in a mutually facing position to exert a supporting and contrasting action on one another, possibly transmitted through the counter-template separating baffles, so as to contrast and distribute the thrusts exerted by the expanding foam in said first (2a) and second (2b) objects placed mutually parallel and alongside; vi). contrasting from the exterior on said foaming operative module (10) located on said rotatable storage structure (6) the thrusts exerted by the expanding foam by a contrasting action exerted by said hooking and clamping means (11).

Description

METHOD AND APPARATUS FOR SIMULTANEOUSLY FOAMING TWO OR MORE OBJECTS

BACKGROUND OF THE INVENTION

The present invention relates to a method and an apparatus for simultaneously foaming two or more objects, such as doors for a refrigerator, for a display counter, for a building or the like, and, in general, panels or objects, which are mostly substantially two-dimensional, i.e. having two prevalent dimensions compared with a third dimension, and provided with external coating elements, such as half shells or plastic or metal shaped panels, or flat, curved or corrugated slabs or sheets, between which coating elements a thermally insulating intermediate layer in polyurethane or phenolic material has to be interposed. PRIOR ART

The process for foaming doors for domestic, commercial and industrial refrigerators currently mainly uses two different basic technologies for conveying and maintaining the doors in respective moulds during the production cycle. A first technology is based on conveying the doors by means of a plant that includes a rotating drum carousel. On the drum carousel, which is rotatable around a horizontal rotation axis, mould-holding presses are housed, which are generally from three to twelve, each mould-holding press comprising two upper and lower containing and pressing surfaces, that are suitable for being positioned according to respective horizontal planes and parallel to one another, the distance from one to the other is variable.

To the surfaces the respective upper and lower half moulds are hooked that are suitable for containing in shape the doors when the expanding foam fills the doors exerts a pressure that may reach values of 6 - 8 Newton for square centimetre.

The upper pressing surface is openable as a book with rotation also up to 120°. Each pair of half moulds and thus each mould-holding press (Note that the press is only one also containing two or three moulds consisting of an upper and lower half mould) is configured and set up for foaming just one door or a sole set or kit of doors for a single refrigerator consisting of two or three doors of different dimensions. On the two lower and upper pressing surfaces respective half moulds are fixed that that support and maintain in position and in shape the respective shaped half shells or shaped panels intended for defining the external face and internal face of the door with respect to the chamber of the refrigerator on which it has to be mounted. A mould-holding press is provided for each pair of coupled half moulds. The mould- holding presses are thus mounted on the drum carousel, and are dragged in rotation integrally with the latter.

In the case of an open mould process, the two half moulds are kept initially separate during pouring of the polyurethane mixture and are subsequently mutually coupled and closed on one another before expansion of the foam.

Otherwise, in the case of a closed mould process, the two half moulds are preventively closed to form a hollow box element before permitting injecting of the polyurethane mixture, which occurs through a side hole made in the mould and in the coupled half moulds. An operator loads the half shell of the outer face of the door on the upper half mould and the half shell of the internal face (e.g. an element made of thermoformed plastics) on the lower half mould, and the drum carousel proceeds by steps. In the zone dedicated to the operator, the foamed door is unloaded and the half moulds, or casings for foaming the doors to be formed are loaded. One, two or three doors are can be loaded simultaneously, that correspond to a set of doors of a single refrigerator. The polyurethane mixture injection and the foam polymerisation step can thus occur whilst the drum carousel rotates by subsequent steps. For removing a foamed door and subsequently loading a new door to be foamed the operator needs about 20-30 seconds, also considering the foaming, closing and advancement of a step, a total of 40 to 60 seconds are required, whilst for polymerisation 3 to 4 minutes are necessary for each door being processed. This plant, above all because of the multiplicity of presses and corresponding driving devices on the drum carousel, is very complex from the structural and functional point of view. Further, the structural complexity involves, from the dynamic point of view, significant inert masses that impose functional and productive limits on the entire plant.

A second technology involves conveying the doors by a plant equipped with a double- chain so-called "paternoster" conveying device. The double-chain conveying device is conformed for supporting and dragging a plurality of mould holders, varying in number for example from 8 to 40 mould holders. Each mould holder can contain a pair of half moulds for foaming a single door or a single set of doors for a single refrigerator.

It is necessary for the mould holders to be maintained according to horizontal planes. This occurs by a suitable coupling of the chain elements with respective driving pinions. To perform the different steps of extracting the foamed door, inserting new half shells to be foamed etc., normally at least two operators are needed but in some cases even five are needed.

It is in fact necessary, to meet set standards required by refrigerator manufacturers, that no geometric distortions occur on the shells of the doors beyond a certain acceptability threshold and to do so, in the case of the dual-chain plant, resort is made to moulds and mould holders that are quite robust, made of metal with considerable thicknesses to be able to automatically contrast the thrusts that are generated in several directions in each door during the foaming step or, in the case of the drum plant, recourse is had to robust presses, which are also heavy and structurally complex. This is all naturally translated into great weight and inertia that inevitably also influence the speed and thus the productivity of such plants. Further, for both the plants disclosed above, loading/unloading times for each single door or each single set of doors are required but it is not possible to foam two sets of doors simultaneously with a single plant.

It would therefore be desirable to simplify and modify both structurally and functionally the plants, also improving the versatility thereof, so as to enable several sets of doors to be foamed simultaneously, thus doubling productivity and also limiting the overall dimensions of the plant. OBJECTS OF THE INVENTION

One object of the present invention is to improve the methods and apparatuses for foaming doors, in particular refrigerator doors, or more in general substantially two- dimensional objects.

Another object is to supply a foaming apparatus that is significantly simplified both from the structural and from the functional view, that is constructionally simple, has a reduced cost and overall dimensions, that permits greater functional flexibility, very high productivity, with great reduction of the time dedicated to loading/unloading doors, and a general improvement of the quality of the door-foaming process.

In current refrigerator manufacture, especially of domestic type, there is a tendency to diversify the various models by in particular modifying the aesthetic appearance, especially the geometric shape, of the respective doors, which are often the main element of attraction, which is decisive in the choice and purchase by consumers. The increasing number of refrigerator models entails an equally growing number of geometric shapes of the corresponding doors, with a consequent increase in the containing moulds dedicated for the corresponding manufacture. Another object of the invention is thus to provide a solution that enables rational and optimised managing of the increasingly great number of geometric shapes of doors, which are often different from one another, obtaining plant productivity that is at least double and reducing as far as possible undesired down time during manufacturing and also limiting overall dimensions of the plant. SHORT DESCRIPTION OF THE INVENTION

These and other objects and advantages of the invention are achievable by a method according to what has been defined in claim 1 and by means of an apparatus according to what has been defined in claim 13.

The method and apparatus according to the invention enables the objects mentioned above to be obtained.

In particular, the principle on which the method and apparatus according to the invention is based is that of exploiting a reciprocal exchange of pressure forces of the foam expanding in the interface zone between the two doors or objects alongside and opposite, i.e. in a specular position to one another, or next to one another with the external face of an object placed parallel to and near the internal face of the homologous object, and both subject to a simultaneous foaming process.

Further features and advantages will be clear from the appended claims, figures and description that follow.

SHORT DESCRIPTION OF THE DRAWINGS

The invention can be better understood and implemented with reference to the attached drawings, which illustrate an embodiment thereof by way of non-limiting example, in which:

Figure 1 shows an apparatus for foaming doors for refrigerators according to the invention in a first operative position;

Figure 2 shows an enlarged detail of Figure 1, in which a gripping and transferring device for a foaming operative module for doors is more visible;

Figure 3 shows the apparatus in a second operative position, in which the gripping and transferring device is in a raised position and near a rotatable storage structure for the foaming operative modules;

Figure 4 shows an enlarged detail of Figure 3;

Figure 5 shows the apparatus in a third operative position, in which the gripping and transferring device is coupled with a foaming operative module removed from the storage structure at the end of a foaming cycle; Figure 6 shows an enlarged detail of Figure 5;

Figures 7 and 8 are side views in which the rotatable storage structure of the apparatus is in two different operative positions;

Figure 9 is an enlarged detail of Figure 7;

Figure 10 is a top view of the apparatus;

Figure 11 is a longitudinal section taken along a horizontal plane of the apparatus on which four doors are foamed simultaneously, (two complete sets for two refrigerators) and in which mixing heads are visible that are arranged on opposite sides of the storage structure and rotatable support.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the enclosed Figures, an apparatus 1 is shown for simultaneously foaming two objects or two or more pairs of objects, in particular doors or pairs of doors 2a, 2b for a refrigerator of domestic or industrial type. Although the following description refers to foaming doors for refrigerators, the apparatus 1 can also be used for foaming lid doors for chest freezers, insulating panels for display counters, doors and windows for houses and buildings, and more in general any mostly two- dimensional object, i.e. having two dimensions greater than a third dimension.

As will be clearer from the description that follows, the particularity of the method and of the apparatus 1 according to the invention is the fact of being able to exploit the reciprocal exchange of pressure forces of the expanding foam by the opposite doors, which occurs in the interface zone between the two doors during the simultaneous process of injection and expansion of the reactive mixture. The opposite doors can be in a specular position to one another or with the internal face of one door near the external face of the other door, as disclosed further on.

The objects to be foamed by the apparatus 1 are provided with external coating elements 3, such as half shells or plastic or metal shaped panels, or flat, curved or thermoformed plates or sheets, coupled to form a hollow box element possibly having a circumferal seal between which foaming occurs to generate an intermediate layer in thermally insulating polyurethane or phenolic material 4.

The apparatus 1 comprises one or more first containing units 5 a each suitable for containing two coating elements, in particular two half shells or two pairs of half shells 3e, 3i for a first object, in particular for a first door or pair of doors 2a.

The apparatus 1 comprises one or more second containing units 5b, each suitable for containing two further coating elements, in particular two further half moulds or two pairs of half moulds 3e', 3i' for a second object, in particular for a second door or pair of doors 2b.

The first 5 a and second 5b containing units are configured to be brought next to one another in a closed position so as to define together a single foaming operative module 10 that in this manner contains simultaneously the two doors or pairs of doors 2a, and 2b. The homologous and opposite containing units 5a, 5b, are shaped for housing two respective doors or pairs of doors of substantially the same shape, in opposite positions mirroring one another, or, as already said, with the face or internal side of a door opposite the face or external side of the other door substantially geometrically the same.

The apparatus comprises a rotatable storage structure 6, on which foaming and polymerisation of the doors occurs. The rotatable storage structure 6 is provided with housing means 7 for each foaming operative module 10 and associated therewith there is a door loading /unloading station 13 in which one or two operators operate. The loading/unloading station is defined by gripping and transferring means 13, disclosed below in greater detail.

The rotatable storage structure 6 is in particular rotatable around a horizontal axis. On the rotatable storage structure 6 there are provided hooking and clamping means

11 which are conformed for removably hooking, supporting and clamping in a closed position each foaming operative module 10 and contrasting from the exterior and from opposite sides on each foaming operative module 10 the thrusts of the expanding foam.

The hooking and clamping means 11, in the embodiment shown in a non-limiting manner in the enclosed figures, comprises two opposite series of jack devices 11 aligned along each housing seat 7. The jack devices 11 comprise protruding elements that are drivable for moving and protruding along respective directions that are transverse to the rotation axis of the rotatable storage structure 6, so as to engage with respective hooking seats obtained on opposite faces of each foaming operative module 10.

The apparatus 1 is associated with a unit for dosing and mixing reactive resins that is per se known and is not shown in the drawings that is configured for injecting the reactive mixture in synchronism with the foaming operative module 10 oriented according to a vertical plane if working with homologous doors or pairs of doors that are mutually specular, i.e. positioned to mirror one another. In other words, each foaming operative module 10, before receiving the reactive mixture, is arranged in such a manner that the coating elements or half shells 3 are arranged according to respective mutually parallel planes. In other words, the doors, during foaming, lie on vertical planes, and said doors can lie there with the longitudinal axes arranged vertically or horizontally. This arrangement has the advantage of filling better the ribbing of the internal thermoformed part (internal half shell) and the advantage of avoiding an accumulation of air on the external surface (metal sheet or external half shell) of the door, as on the other hand occurs in normal prior-art drum plants where the half shells are arranged according to horizontal planes during foaming with the external side placed above or below, according to the plants.

In another possible embodiment of the method and of the apparatus, the internal face of a door 2a opposite the external face of the other door 2b that is substantially geometrically the same is placed inside the foaming operative module 10. In this case, the foaming operative module 10, prior to the injection, is positioned according to a severely tilted plane, i.e. having a tilt comprised between 0° and 45° with respect to the vertical plane, so that also the coating elements (3, 3i, 3e, 3i', 3e') or half shells are thus tilted, parallel to one another.

This operating mode advantageously entails saving an advancement step of the rotatable storage structure 6, as will be explained more clearly further on in the description. This operating mode further enables a sole hole for injecting the mixture to be used, which hole is made in the same position near the bottom vertex (corner) on the respective homologous doors. In fact, differently, in case of mirrored or specular positioning of the two homologous doors, two holes are required for delivering the reactive resin into the two corners of the same side of a door. In fact, there were only one hole, placed near a corner, such a hole would be located at a greater height during injection, whereas the other homologous hole of the other door would be at a lower height during the injection, with consequent clear foam expansion modes that were not perfectly specular. Once compromise solution that permits working with the doors placed in a mirrored/specular position is to exploit injection holes that are made not at the vertices but in central zones of the lateral sides of the half shells.

Each foaming operative module 10 comprises separating means or baffles with counter-template function and transfer of the thrust of the foam 12 suitable for being interposed between the two half shells 3i and 3i' respectively of the first door or pair of doors 2a and of the second door or pair of doors 2b, which are (placed mutually alongside) close and in a mutually facing position to one another. In particular, the baffles with a counter-template function and which transfer the thrust of the foam 12 comprise two distinct foam thrust-transferring and separating elements 12a, 12b that are coup lab le both in contact with one another and with the respective first half shells 3i, 3i' of the two opposite doors 2a, 2b and with the two respective containing unit 5a, 5b.

The apparatus 1 can thus be configured to include, and operate with, any desired number of foaming operative modules 10. For example, as shown in a non-limiting manner in the enclosed figures, six distinct foaming operative modules 10 are provided, each comprising at least one first containing unit 5 a and at least one second containing unit 5b. In this case, the rotatable storage structure 6 correspondingly comprises six distinct housing seats 7 for the six foaming operative modules 10.

In particular, in a non-limiting manner, each foaming operative module can be configured for permitting simultaneous foaming of four distinct doors, or also six doors if they are suitably arranged along the module 10 so as to have injection holes that are accessible to the pairs of foaming heads 8, these four distinct doors all being able to be substantially geometrically the same as one another or to be the same as pairs. For example, as visible in section in figure 11, the foaming operative module 10 comprises on one side two distinct containing units 5 a, 5 c, and on the other side two further distinct containing units 5b, 5d. The containing unit 5c is intended to be opposite the containing unit 5d, similarly to what occurs to the two containing units 5a and 5d that can be placed mutually opposite. The doors 2a and 2b have dimensions and a geometric shape that are substantially similar to one another. Analogously, the doors 2c and 2d have dimensions and a geometric shape that are substantially similar to one another, but if possible different from the doors 2a and 2b. In fact, the door 2a and the door 2c can together define a first pair (first set or kit) of doors intended for a single refrigerator, whereas the door 2b and the door 2d can together define a second pair (second set or kit) of doors intended for a further single refrigerator.

In other words, two distinct pairs (sets) of doors, each pair intended for a respective refrigerator can be foamed. Each pair can thus comprise a door of greater dimensions, intended to close a larger compartment of the refrigerator, for example the food freezer compartment, and another smaller door or two other doors to be associated with respective further compartments of this refrigerator (for example, the freezer compartment, etc.). Thus in general, each foaming operative module 10 can comprise one or more first containing units 5 and one or more respective second containing units 5, with the respective foam thrust-transferring and separating elements 12 associated, so as to contain two, four, six or another desired number of pairs of half shells intended for foaming correspondingly two, four, six or another desired number of doors.

The various containing units 5 that lie on the same plane can be mutually connected together, also by a simple metal plate, in such a manner that the foaming operative module 10 is, in the closed position thereof, a single body, enabling the module 10 to be more easily moved and transferred from the one zone of the apparatus 1 to the other zone thereof.

Each foam thrust-transferring and separating element 12a, 12b is provided with a perimeter zone suitably shaped for coupling with the respective containing unit 5a, 5b and for containing, in the correct position and geometric shape, a possible seal normally applied to the perimeter edge of the doors or the refrigerators. Coupling provides, as is more visible in Figure 9, a groove 22 made in the foam thrust- transferring and separating element 12 that receives an edge 23 of the respective containing unit 5, in which conjugate tilted surfaces come into reciprocal contact in such a manner as to ensure the correct positioning of the foam thrust-transferring and separating element 12 in relation to the associated containing unit 5. These coupling perimeter surfaces also have the function of transferring the thrust of the jack devices 11 between the various separating elements and can also be provided with a perimeter seal that enables each containing module to be sealed and a vacuum to be created there to promote and accelerate the expansion of the foam. It is not necessary to dimension with great thicknesses or robust reticulated structures the counter-template baffles 12a and 12b, resting on one another. In fact, owing to the configuration disclosed above, every single baffle or foam thrust-transferring and separating element 12a, disposing along their entire resting surface of the other baffle or foam thrust- transferring and separating element 12b and receiving from the latter a contrasting action during the symmetrical expansion, is not forced to perform alone the action of contrasting the thrust of the expanding foam over the entire surface thereof in the containing unit associated therewith. In other words, the thrust actions of the foam that are generated on the surfaces of the opposite containing units 5a, and 5b and act on the foam thrust-transferring and separating means 12a, 12b, are opposite one another but have values that are substantially equal by virtue of the fact that the homologous and opposite containing units 5a, 5b, house two respective doors of about the same shape. Thus, with methods for injecting the polyurethane or phenolic mixture that are substantially the same in the two opposite containing units 5a, 5b thrust actions are generated on the opposite surfaces that are exerted by the expanding mixture and act from opposite directions with substantially equal values on the two foam thrust-transferring and separating elements 12a, 12b. In other words, the two opposite thrusts of the expanding foam acting on the two foam thrust- transferring and separating elements 12a, 12b elide with one another. The foam thrust-transferring and separating elements 12a, 12b are thus subjected on the internal surfaces only to loads of a value that is substantially the same on the opposite sides that are balanced and thus do not per se have to perform counter-thrust actions that would on the other hand require dimensioning with appropriate flexure with a structure of greater thicknesses or a reticulated structure. During an operative cycle, the foam reacts and expands from a few seconds from the injection. As the two flows of mixture expand simultaneously and symmetrically, the pressure exerted on a back wall (i.e. on the foam thrust-transferring and separating element 12a) of a containing unit 2a is balanced by the pressure of the foam on the back wall (i.e. on the further foam thrust-transferring and separating element 12b) of the opposite containing unit 2b, enabling the clamping force of the two jack devices 11 to be simultaneously applied at least on two opposite containing units 5.

In this condition, the counter-template baffles 12a, 12b perform on the internal surfaces a mere action of separating and positioning the two opposite half shells 3i, 3i' whereas the thrust of the jacks is transferred from the couplings along the perimeter. In other words, the counter-template baffles 12a, 12b act as geometric adapters for resting and reciprocal positioning of the half shells 3i, 3i', which can, for example, be convex, i.e. have convex or anyway non-flat surfaces in the case of a mirrored and specular arrangement of the doors, and have shapes that are different from one another in the case of an arrangement of homologous doors in a "stacked" position, with the internal face of the one next to the internal face of the other. The counter- template baffles 12a, 12b are thus used simply for copying and maintaining the geometric, for example concave, shape of the outer surfaces of the opposite doors, or for copying and maintaining the outer concave geometric shape of a door on one side, and, on the other side, the more complex and varied geometric shape of the internal face of the other door. Advantageously, thus, unlike prior art plants in which moulds and mould holders enable a single door to be foamed or a single set of doors at a time, with the method and the apparatus 1 according to the invention two doors or two sets of doors are simultaneously foamed, thanks to the foaming operative modules 10 that at the same time are also structurally lighter and simpler owing to the operating principle thereof based on the exploitation of the reciprocal exchange of force of equal and opposite pressure arising from the expanding foam in the respective opposite doors.

If it is desired to foam simultaneously two panels or two doors having flat outer surfaces it is also possible to do without the thrust-transferring and separating means 12, placing in reciprocal contact and resting the flat half shells or the plates/sheets that are placed further inside the foaming operative module 10. In this case, it will be these flat half shells or mutually opposite plates/sheets that will exchange equal and opposite forces, mutually balancing and contrasting the reaction thrusts of the expanding polyurethane or phenolic mixture. Also in this case the aforementioned operating principle is exploited that is based on the reciprocal exchange of equal and opposite pressure forces on the opposite surfaces arising from the expanding foam in the respective opposite doors.

Experiments testify to the good operation of the foaming operative modules 10 with or without separating intermediate elements 12 depending on the geometric shapes of the objects/doors to be foamed.

With half moulds or coating sheets that are very thin, thus very yieldable, it is thus sufficient to interpose as a thrust-transferring and separating element 12, a simple plywood panel that is 6 mm thick to obtain positive results from simultaneous double foaming. The fact that such a thin panel of plywood was found to be sufficient is proof of the fact that with doors to be foamed having substantially the same shapes and by acting with methods of injection of the mixture that are the same and simultaneous inside the one and the other door, a prevalent action of containing and contrasting the expanding is, in a substantially total manner, performed by the opposition of pressure forces that are the same and opposite that the two doors placed in an opposite and mirrored position exchange reciprocally along the surfaces. In other words, a simple baffle, consisting of the plywood panel, was able to permit a good outcome of the test because the unbalanced thrust borne by the baffle was minimal, estimable as a thirtieth of the total thrust necessary for contrasting the expansion of the foam and holding in position and shape the two doors, i.e. for ensuring the shape stability thereof. The rest of the thrust arising from the expanding foam is distributed and reciprocally exchanged by the two doors through the surfaces, whereas the thrust of the jack devices 11 that also contrasts the thrust of the foam outside the foaming operative modules 10, is transmitted along the perimeter zones without geometric distortions occurring that are such as not to meet the standards set generally imposed and accepted by refrigerator manufacturers.

This means that it is also possible to do without the separating intermediate elements 12 but simple perimeter frames are sufficient in the specific cases in which half shells or coating sheets have a flat shape and a certain minimum thickness that is not great but is sufficient to provide a certain stiffness.

As mentioned above, the loading/unloading station for the doors comprises gripping and transferring means 13 by means of which each foaming operative module 10 can be opened to enable one or more pairs of half shells to be foamed to be introduced, can be reclosed as a "sandwich" and transferred to a respective housing seat 7 where two opposite series of jack devices 11 ensure firm closure and anchoring to the rotatable storage structure 6. The gripping and transferring means 13 is moved vertically, i.e. raised and lowered by a special handling device which can be hydraulic, electric, pneumatic, so as to allow to load/remove each foaming module operative module 10 to be loaded on/removed from the rotatable storage structure 6.

In the loading/unloading station two adjacent stations are provided for two operators entrusted with loading/unloading the respective pairs of foaming/foamed doors. A single station for a sole operator can be provided and in this case the gripping and transferring means 13 is configured for being rotatable around a vertical axis to enable the single operator to load the doors to be foamed or unload the doors already foamed.

The gripping and transferring means 13 comprises a pair of grippers 13a, 13b each provided with a first engaging lever 14, and a second engaging lever 15. The first engaging levers 14 are suitable for engaging with a respective containing unit 5a, 5b, whereas the second engaging levers 15 are suitable for engaging with the separating elements 12a, 12b that act as a thrust-transferring counter-template. Each first engaging lever 14 and the associated second engaging lever 15 are driven by suitable kinematic mechanisms that are differentiated between one another so as to move along paths of different length so as to move each containing unit 5a, 5b to/from the respective thrust- transferring and separating element 12a, 12b and enable an already foamed door to be extracted and the pair of half shells to be introduced for foaming a subsequent door.

The levers of the first gripper 13a move symmetrically in an opposite direction to the homologous levers of the second gripper 13b.

In particular, whilst the separating elements 12 are rotated by an angular amount up to -45°, the containing units 5 are on the other hand rotated, with respect to the vertical plane, by an angle that can reach a value comprised between -90° and -150°.

The two grippers 13a, 13b are movable by a dual-rack device 16 operationally connected to suitable hydraulic or electrical means 21 configured for commanding the simultaneous opening of the two grippers 13 a, 13b. Instead of a dual rack, it is possible to provide a mechanism or a cam or other equivalent means provided that it is suitable for suitably driving the two grippers 13 a, 13b. In particular, the first engaging lever 14 and the second engaging lever 15 of each gripper 13 a, 13b are rotatable in opposite directions and by opposite angular amounts by differentiated meshing means 20 that, in addition to the aforesaid dual-rack device 16, includes pinions 17, 18 of a different diameter associated with the respective first 14 and second 15 engaging levers.

The grippers 13, by opening the containing units and the separating elements and counter-template 12 in tilted positions, ergonomically provided easy accessibility and manoeuvrability for the operator/s. In this manner, the operator can easily extract/introduce one or more foamed doors or doors to be foamed and perform cleaning, maintenance, preparing tasks, etc.

Alternatively to the pinions, cams and connecting rods or thrust counter-levers can be provided that are configured for differentiating the opening rotation movement of the first 14 and second 15 lever, and thus of the thrust-transferring and separating means 12 and of the containing units 5 in relation to one another.

The apparatus comprises two or more mixing heads 8, in particular four heads 8, each dedicated to a respective door 2 and suitable for being inserted automatically in a corresponding lateral injection hole for dispensing into the coupled half shells the polyurethane or phenolic mixture. In the case of only two doors to be foamed there will be only two mixing heads 8, whereas in the case of simultaneous foaming of four doors there will be four mixing heads 8, distributed in pairs on two opposite sides of the rotatable storage structure 6 and thus on opposite sides of each foaming operative module 10.

The mixing heads 8 can be moved by suitable hydraulic or electric actuators etc, to be moved near, sliding on suitable guides, the foaming operative module 10 before injecting the reactive mixture. On the outer sides, i.e. on the end sides according to a direction parallel to the rotation axis of the rotatable storage structure 6, on each containing unit and respective half shells contained therein one or more openings or holes are obtained for accessing the mixing and injection heads 8.

The mixing heads 8 act to inject simultaneously, or alternately by pairs of heads, the distinct flows of polyurethane or phenolic mixture in the distinct doors 2a, 2b, whereas the various half shells 3, 3i, 3e, 3i', 3e' are oriented inside the respective foaming operative module 10, according to respective mutually parallel planes and placed vertically or tilted between 0° and 45 degrees with respect to the vertical plane. In an operative mode, the injection occurs first with the pair of heads located on the right side (e.g. for 3-4 sec) and then with the pair of heads on the left side. The principle of balance and reciprocal exchange of thrust is also assured in this mode. This mode has the advantage of easier and more economical operation of the mixture dosing unit.

The substantial specularity in terms of geometry and position of the pairs of doors opposite one another enables the advantageous effect to be obtained of self-balancing the forces of the pressure generated by the expansion of the foam, where the pressure, for example, varies during the expansion step from 0.4 to 0.6 bar, reaching up to 0.8 bar in particular overpacking conditions. One possible but non-limiting configuration provides a dosing unit that manages the four heads 8 with a pair of dosing pumps for each head or a pair of dosing pumps for each pair of heads acting on the same side of the foaming operative module.

In one non-limiting embodiment of the apparatus, each mixing head 8 is configured for injecting each flow of polyurethane or phenolic mixture with a double injection with a variable flow rate. More specifically, the flow rate of injected mixture can be modified by a greater initial value, that is useful for reaching zones of the respective door to be foamed that are further from the respective mixing head 8, at a lower final value (also closing and reopening the mixing box) to affect zones of the door that are on the other hand nearer the mixing head 8. The mixture is then distributed inside each door in a homogenised and optimised manner. The apparatus 1 can be provided with means generating a certain vacuum degree, i.e. air-sucking means that are suitably moved in a similar manner to the mixing heads 8 and placed alongside the foaming operative module 10 to form a seal. In this case, on the sides of each foaming operative module containing shoulders with conical or cylindrical holes are placed that are suitable for housing a seal. One hole is engaged by a mixing head 8 that thus acts as a plug, whereas another hole, placed in a higher position than the same containing unit, is sealingly occupied by an air-sucking nozzle. In the case of use of a sole central hole, the vacuum is made on the containing unit and enters the respective casing, or coupled half shells, by vents for the air that are defined along the junctions of the internal half shell (i.e. internal thermoformed part) with the outer half mould (i.e. outer sheet) of the door.

The air-sucking means, comprising sucking nozzles, and connected to a pneumatic circuit, acts to suck air from the respective foaming operative module 10 to generate a degree of vacuum in the interior thereof, so as to facilitate and accelerate the expansion of the foam and optimise distribution of the foam during expansion.

The vacuum accentuates the speed of expansion of the foam and enables lower intensity, more homogeneous and small cell structure and a polymerisation reaction speed that is higher than 30- 40% to be obtained.

Adopting the vacuum and variable flow rate advantageously enables a reduction of 2- 3% in the polyurethane mixture to be obtained that is necessary for filling each door. The sucking nozzles are drivable in a manner that is operationally correlated with the associated mixing and injection heads 8 and enable, by removing the gases that form inside the foaming operative module 10, during expansion, the cavity to be protected from the risk arising from the use of evaporating flammable expanding agents and a better distribution of the polyurethane mixture to be obtained, improving the foaming process overall.

The rotatable storage structure 6 is housed in a hot air kiln 21 , in which prior heating of the foaming operative modules 10, injection into the latter polyurethane or phenolic mixture and subsequent polymerisation occur.

The operation of the apparatus 1 is now disclosed concisely.

When the grippers 13a and 13b with the respective containing units 5a, 5b, and the counter-template separating elements 12a and 12b are in an open position, each operator removes the pairs of already foamed doors and inserts new pairs of half shells that can already be in pre-assembled form to form the respective casings of the doors. In other words, each operator loads a respective kit of doors intended for a respective refrigerator. The half shells or casings can be in pre-assembled form or also be separated between the internal and outer part of the doors.

On the moulds specific housings and magnets are provided for positioning and keeping in shape the shells before and after the foaming process.

Once the new shells have been loaded, each operator moves away by a step in order to free and not interfere with the parts of the apparatus 1 ready to move, and enables the grippers 13a and 13b to close as a "sandwich" and in a vertical position the foaming operative module 10 that has just been loaded, with the two doors or two pairs of doors opposite one another, in a mirrored specular position, or according to the other mode, in a stacked position with an internal face of a door facing the outer face of the homologous door. The vertical handling device with hydraulic or electric command lifts the grippers 13 and the foaming operative module that, sliding on suitable guides, is inserted into a housing seat 7 of the rotatable storage structure 6.

The corresponding jack devices 11 hook onto and press with force from opposite sides the foaming operative module 10. The containing units 5 of the operative module 10, which are opposite one another, exchange in this manner the clamping force along their edges. After the hooking step, the grippers 13a 13b open and the rotatable storage structure 6 advances forward by an angular step, taking the foaming operative module 10 that has just been loaded with the empty shells to a waiting position when heating takes place; at the same time, a further foaming operative module 10 containing already foamed and polymerised doors is brought in correspondence with grippers 13 which hook this foaming operative module 10 and after the corresponding jack devices 11 are released, lower this foaming operative module 10 in order to enable it to be opened and unloaded by the operators. At this point, the rotatable storage structure 6 goes back by one angular step, returning the foaming operative module 10 that has just been loaded to a vertical position to enable the mixing heads 8, placed centrally in the lower zone of the structure 6, to be inserted automatically into the lateral injection holes for injecting the polyurethane mixture simultaneously into the right and left containing unit/s 5. The heads 8 remain inserted, for about 10-12 seconds, to enable the doors to be totally filled with the expanding foam.

Alternatively, injecting can occur without retreating by an angular step being necessary: the injection heads, placed an angular step forward the zone in which hooking/unhooking of the modules 10 occurs, inject with the operative module 10 in question located not in a vertical position but, as said above, in a tilted position, for example at 45° with respect to the vertical plane. The drive of the structure 6 and in general the productive cycle is thus simplified further. For this operating mode it is not necessary for the homologous doors to be positioned mirroring one another, but they can also be loaded with the same orientation or direction, i.e. with the outer face of a door such as to be next to the internal face of the other homologous door.

The mixture reacts and expands after a few seconds from the injection. The simultaneous and symmetrical expansion of the flows of mixture means that the pressure exerted on the back surface of a containing unit 5 is balanced by the pressure of the foam on the surface on the back of the further opposite containing unit 5, enabling a clamping force of the jack devices 11 to be applied simultaneously to the two opposite units that is of the same amount as the clamping force applied to a sole unit.

The apparatus proceeds cyclically, making the rotatable storage structure 6 advance by two angular steps forwards and one backwards or by only successive steps forwards, as just disclosed.

All the aforesaid operations take about 20-30 seconds and mask the operations of the foaming rotatable structure 6. During the mixture reaction, the rotatable storage structure 6 rotates by steps around the horizontal axis thereof, permitting polymerisation inside the air kiln 21.

In one possible embodiment, it is possible to load already pre-assembled shells and unload the foamed doors by means of a conveyor coupled with a lateral device for inserting into the grippers, which, in this eventuality, will have a smaller opening width as no operator is required.

As can be appreciated from what has been disclosed, the apparatus 1 and the relative method enable the above objects to be achieved. In particular, high versatility of use and apparatus 1 productivity is achieved that permits simultaneous foaming of at least two doors or two pairs of substantially identical doors, which is not currently obtainable with prior-art apparatuses. The apparatus 1 permits extreme flexibility, with the possibility of adapting in real time to variable geometric shapes of the half shells of a door, without this having to entail undesired prolonged machine downtime. The rotatable storage structure 6 is structurally simplified and light, devoid of heavy and complex prior-art press-mould-holding devices. More homogeneous foaming is obtained with great reduction, or even absence, of air bubbles, and better filling of the ribbing of the internal half shell (internal thermoformed "liner") of each door, intended for housing various compartments and boxes (e.g. egg rack, etc.).

The rotatable storage structure 6 and the foaming operative modules 10, owing to the structurally simplified configuration thereof, bring greater mechanical reliability and reduced weights and overall dimensions. As the inertia mass is reduced, the apparatus can also be driven faster than prior-art apparatuses.

It is possible to configure and dimension the apparatus 1 in a desired manner according to the dimensions/type of objects to be processed and variations and/or additions are possible to what has been disclosed and illustrated in the attached drawings.

Claims

1. Method for simultaneously foaming two or more objects (2, 2a, 2b, 2c, 2d) each having two dimensions prevailing on a third dimension and being provided with two outer coating elements (3, 3i, 3e, 3i', 3e') of the shell type or shaped panel type or of the flat, curved or thermoformed slab or sheet type, between said two outer coating elements (3, 3i, 3e, 3i', 3e') there being interposed an intermediate layer (4) of expanded polyurethane or phenolic material, characterised in that it comprises the steps of:

i). inserting two coating elements (3i, 3e) of a first object (2a; 2c) inside a first containing unit (5a; 5c), and two further coating elements (3i', 3e') of a second object (2b; 2d) inside a second containing unit (5b; 5d);

ii) . bringing said first containing unit (5 a; 5 c) and said second containing unit (5b; 5d) next to one another so as to define a single foaming operative module (10) containing two or more objects (2, 2a, 2b, 2c, 2d) to be foamed simultaneously, wherein, inside said foaming operative module (10), the coating elements (3, 3i, 3e, 3i', 3e') of the first object (2a; 2c) and of the second object (2b; 2d) are arranged according to respective mutually parallel planes, and a coating element (3i) of said first object (2a; 2c) and a respective coating element (3i') of said second object (2b; 2d) are near to one another in a mutually facing position;

iii) . hooking said forming operative module (10) on a rotatable storage structure (6) that is provided with hooking and clamping means (11) and housing means (7) for each foaming operative module (10);

iv) . dispensing distinct flows of polyurethane or phenolic mixture each inside a respective object (2, 2a, 2b, 2c, 2d) to be foamed, wherein said dispensing occurs simultaneously in all the objects or simultaneously at first in a pair of mutually facing objects and subsequently in a further pair of mutually facing objects;

v) . enabling the coating element (3i) of said first object (2a; 2c) and the coating element (3i') of said second object (2b; 2d), which are placed in a mutually facing position, to exert a supporting and contrasting action on one another, so as to contrast and distribute the thrusts exerted on the surface of the coating elements from the expanding foam in said first (2a; 2c) and second (2b; 2d) objects placed mutually parallel and alongside;

vi). contrasting from the exterior on said foaming operative module (10) located on said rotatable storage structure (6) the thrusts exerted by the expanding foam by a contrasting action exerted by said hooking and clamping means (11).

2. Method according to claim 1, wherein between the coating element (3i) of said first object (2a; 2c) and the coating element (3i') of said second object (2b; 2d), which are nearer one another in a mutually facing position, counter-template means (12, 12a, 12b), included in said foaming operative module (10), is interposed to separate and transfer the thrust of the foam along the surface, and which acts to position, maintain in the desired geometric form or shape, and separate from one another the adjacent and opposite coating elements (3i, 3i') and to receive, contrast and distribute the thrusts that from opposite sides are generated on the surface by the expanding foam in said first (2a; 2c) and second (2b; 2d) objects, said foam- thrust- transferring and separating counter-template means (12, 12a, 12b) receiving and transmitting along peripheral edges thereof coupled with, and pressed by, said containing units (5a, 5b, 5c, 5d) the clamping actions exerted by said hooking and clamping means (11).

3. Method according to claim 1 or 2, wherein during said simultaneous dispensing step iv.), said foaming operative module (10) is positioned parallel to a vertical plan or according to a plane tilted between 0° and 45° with respect to said vertical plan, in such a manner that said coating elements (3, 3i, 3e, 3i', 3e') are correspondingly oriented according to respective planes that are mutually parallel and tilted between 0° and 45° with respect to said vertical plan.

4. Method according to any preceding claim, wherein said objects comprise doors for a refrigerator, for display counter, for buildings, or the like, and wherein the coating elements of each refrigerator door (2, 2a, 2b, 2c, 2d) comprise a first half shell (3i, 3i'), intended for defining an external side of the respective door, and a second half shell (3e, 3e') intended for defining an internal side of the respective door, wherein each first half shell (3i, 3i') with the respective second half shell (3e, 3e'), during the introduction into said foaming operative module (10), are initially separated from one another or already mutually coupled in a pre-assembled configuration.

5. Method according to claim 4, wherein the two substantially equal doors of each pair are housed in said operative module (10) in a specular manner mirroring an intermediate longitudinal plane of said operative module (10) or are housed parallel to one another with the same orientation, i.e. with the external face half shell of a door close to the internal face half shell of the other homologous door.

6. Method according to claim 4 or 5 as appended to claim 2, wherein two distinct foam-thrust- transferring and separating elements (12a, 12b), included in said thrust-transferring and separating means (12), are used, and said two thrust- transferring and separating elements (12a, 12b) are coupled with one another, with the respective first half shells (3i, 3i') of the two facing doors (2a, 2b), and with the two respective containing units (5a, 5b).

7. Method according to any preceding claim, in which each containing unit (5 a, 5b) is configured for simultaneously containing two or more internal half shells (3i, 3i' ) intended for the production of a set of two or more doors for a refrigerator or the like, and wherein said thrust-transferring and separating means (12) is configured for coupling correspondingly with two or more external half shells (3e, 3e') of said set of two or more doors for refrigerator or the like, said foaming operative module (10) enabling in this manner simultaneous foaming of two sets, each defined by two or more doors.

8. Method according to one or more preceding claims, wherein the distinct flows of polyurethane or phenol mixture are injected into the distinct pairs of half shells (3e,3i, 3e', 3i') by mixing heads (8) located on opposite sides of said rotatable storage structure (6).

9. Method according to one or more preceding claims, wherein loading/removing each foaming operative module (10) onto/from said rotatable storage structure (6) is provided by means of vertically movable gripping and transferring means (13), in which said gripping and transferring means (13) also acts to open/close each pair of opposite containing units (5a, 5b), said gripping and transferring means comprising a pair of grippers (13a, 13b) each provided with a first engaging lever (14) and a second engaging lever (15) that are drivable so as to move and rotate according to paths of differing lengths, so as to mutually space apart/bring each containing unit (5 a, 5b) from/near to the respective thrust-transferring and separating element (12a, 12b) to enable extraction of an already foamed door and insertion of the pair of half shells for foaming a further door.

10. Method according to one or more preceding claims, in which each flow of polyurethane or phenol mixture is introduced with an injection mode having a greater initial flow-rate value, to reach zones of the door to be foamed that are further from the respective mixing head (8), such an injection mode having a lower final value to reach parts of the door that are nearer the mixing head (8).

11. Method according to one or more preceding claims, wherein before injection of polyurethane or phenol mixture a certain vacuum degree is generated and maintained during expansion inside each foaming operative module (10).

12. Method according to one or more preceding claims, wherein there is provided heating the foaming operative modules (10) and injecting in said foaming operative modules (10) the polyurethane or phenol mixture within a heated air kiln.

13. Apparatus for the simultaneous foaming of two or more objects (2, 2a, 2b, 2c, 2d), such as doors for a refrigerator, for display counter, for buildings, or the like, each object having two prevalent dimensions with respect to a third dimension and being provided with two outer coating elements (3), such as half shells (3i, 3e, 3i', 3e') or shaped plastic or metal panels, or flat, curved or thermoformed slabs or sheets, between said two outer coating elements (3) there being interposed an intermediate layer (4) of expanded polyurethane or phenolic material, comprising: - at least a first containing unit (5 a; 5 c) suitable for containing two coating elements (3e; 3i) for a first object (2a; 2c);

- at least a second containing unit (5b; 5d) suitable for containing two further coating elements (3e'; 3i') for a second object (2b; 2d);

- a rotatable storage structure (6) provided with housing means (7) for said at least first (5a; 5c) and at least second (5b; 5d) containing unit;

- mixing head means (8) suitable for simultaneously dispensing distinct flows of polyurethane or phenol mixture inside the respective objects (2, 2a, 2b, 2c, 2d) which are to be foamed and are located on said storage structure (6);

- CHARACTERISED IN THAT said at least a first (5a; 5c) and at least a second (5b; 5d) containing units are configured to be brought next to one another in a closed position so as to define a single foaming operative module (10) suitable for containing said two or more objects (2, 2a, 2b, 2c, 2d) to be foamed simultaneously, wherein in said closed position the outer coating elements (3) of the objects (2, 2a, 2b) are arranged according to respective mutually parallel planes and in which an external coating element (3i) of said first object (2a; 2c) and a respective external coating element (3i') of said second object (2b; 2d) are near to one another in a mutually facing position, said at least a first (5a; 5c) and at least a second (5b; 5d) containing unit being structurally configured to enable, in said closed position, the coating element (3i) of said first object (2a; 2c) and the coating element (3i') of said second object (2b; 2d), which are near and opposite one another, to exchange resting and contrasting forces exerted on one another, so as to contrast and distribute the thrusts exerted by the expanding foam on the surfaces of said first (2a; 2c) and second (2b; 2d) facing objects, and by the fact that on said rotatable storage structure (6) hooking and clamping means (11) is provided that is configured for removably supporting in a closed position each foaming operative module (10) and contrasting from the exterior and from opposite sides on said foaming operative module (10) the thrusts of the expanding foam.

14. Apparatus according to claim 13, wherein each foaming operative module (10) comprises thrust-transferring and separating means (12, 12a, 12b) suitable for being interposed between the coating element (3i) of said first object (2a; 2c) and the coating element (3i') of said second object (2b; 2d) which are nearer one another in a mutually facing position, said thrust-transferring and separating means (12, 12a, 12b) being configured for maintaining in position, separating from one another the adjacent and opposing coating elements (3i, 3i') and for receiving, contrasting and distributing along the surface the thrusts that from opposite sides are generated by the expanding foam in said first (2a; 2c) and second (2b; 2d) objects.

15. Apparatus according to claim 14, wherein said thrust-transferring and separating means (12) comprises two distinct thrust-transferring and separating elements (12a, 12b) that are couplably in contact with one another, with the respective first half shells (3i, 3i') of the two facing doors (2a, 2b), and with the two respective containing units (5a, 5b).

16. Apparatus according to any one of claims 13 to 15, in which each containing unit (5 a, 5b) is configured for simultaneously containing two or more internal half shells (3i, 3i' ) intended for the production of a set of two or more doors for a refrigerator or the like, and in which said thrust-transferring and separating means (12) is configured for coupling correspondingly with two or more external half shells (3e, 3e') of said set of two or more doors for refrigerator or the like, said foaming operative module (10) enabling in this manner simultaneous foaming of two sets, each defined by two or more doors.

17. Apparatus according to any one of claims 13 to 16, comprising gripping and transferring means (13) that is vertically movable for loading/removing each foaming operative module (10) onto/from said rotatable storage structure (6) and for opening/closing each pair of opposing containing units (5a, 5b), wherein said gripping and transferring means (13) comprising a pair of grippers (13a, 13b) each provided with a first engaging lever (14) and a second engaging lever (15) that are drivable by kinematic mechanisms that are different from one another so as to move along paths of differing length so as to mutually space apart/bring each containing unit (5a, 5b) from/near the respective transferring-thrust and separating-element (12a, 12b) and enable extraction of an already foamed door and insertion of the pair of half shells for foaming a further door.

18. Apparatus according to claim 17, wherein the two grippers of said pair of grippers (13a, 13b) are movable by a dual-rack (16) or cam or connecting-rod device that is drivable by hydraulic or electrical means (21), that is configured for commanding the simultaneous opening of said two grippers (13a, 13b).

19. Apparatus according to claim 18, wherein the first engaging lever (14) and the second engaging lever (15) of each gripper (13a, 13b) are rotatable in opposite directions and by different angular amounts by differentiated meshing means (20) that includes said dual-rack device (16) and pinions (17, 18) of different diameter associated with the respective first (14) and second (15) engaging levers, wherein the first engaging lever (14) and the second engaging lever (15) of each gripper (13a, 13b) are rotatable by differentiated driving means that includes cams and relative thrust counter- levers, associated with the respective first (14) and second (15) engaging levers, that act for differentiating the opening rotation movement of the thrust-transferring and separating means (12, 12a, 12b) and of the containing units (5a, 5b).

20. Apparatus according to any one of claims 13 to 19, wherein said gripping and transferring means (13) defines a loading/unloading station located in a region below said storage structure (6), said loading-unloading station having two adjacent stations for two loading/unloading operators of the respective pairs of doors to be foamed/already foamed, or said loading-unloading station having a single station for a single operator and said gripping and transferring means (13, 13a, 13b) being rotatable around a vertical axis to enable said single operator to load/remove the doors to be foamed/already foamed.

21. Apparatus according to any one of claims 13 to 20, wherein said mixing heads (8) are located on opposite sides of said rotatable storage structure (6) and are arranged for injecting into each of the opposite cavities the distinct flows of polyurethane or phenol mixture in a simultaneous manner in all the distinct doors (2a, 2b; 2c, 2d), or at first simultaneously in the two facing doors of a first pair (2a; 2b) of doors and subsequently simultaneously in the two homologous facing doors of the second pair of doors (2c, 2d), the injection occurring with said foaming operative module (10) positioned according to a vertical plane or according to a tilt comprised between 0° and 45° with respect to said vertical plane, in such a manner that said half shells (3, 3i, 3e, 3i', 3e') are correspondingly oriented according to respective planes that are mutually parallel and arranged vertically or at a tilt comprised between 0° and 45° with respect to said vertical plan.

22. Apparatus according to any one of claims 13 to 21, wherein means is provided for generating, and maintaining during the expansion of the foam, a certain vacuum degree inside each foaming operative module (10).

23. Apparatus according to any one of claims 13 to 22, further comprising a hot air kiln (21), in which said rotatable storage structure (6) is housed, and in which the foaming operative modules (10) are heated and the polyurethane or phenol mixture is injected into the foaming operative modules (10).

24. Apparatus according to any one of claims 13 to 23, wherein each mixing head (8) is configured for injecting each flow of polyurethane or phenol mixture at a greater initial flow-rate value, so as to reach zones of the respective door to be foamed that are further from said mixing head (8), and subsequently at a lower final value to reach parts of said door that are nearer the mixing head (8).