BUILDING"

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority from Italian patent application no. 102020000017647 filed on 21/07/2020, the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a 3D-printing system and method, with jetting technique, to automatically build a building. In particular, the present invention concerns the automated building by jetting 3D printing, with powder bed laying, of one or more vertical walls of a building on the basis of a 3D digital model of the walls.

PRIOR ART

Systems and methods are known for the automated building of buildings which are essentially based on the use of an additive technology (additive manufacturing), which provides for carrying out a controlled laying of building material according to printing processes of three-dimensional elements, so-called "3D-printing systems".

Such systems, generally indicated as "3D-printing systems", provide for laying horizontal layers of building material, one on top of the other, so as to form vertical walls, in which such operations are carried out under the control of an electronic control system on the basis of a 3D digital model of the building.

The 3D-printing systems described above are divided into two categories, which depend on the laying modality of the building material adopted.

A first category is represented by the 3D-printing systems that carry out a laying of the building material, generally concrete, by extrusion. Such systems generally provide for the use of one single extrusion nozzle which is mounted on a movable head, and is designed to extrude continuously the concrete at the semisolid state so as to form a continuous semisolid strip of concrete on an underlying horizontal surface plane; a handling system of the head on two or more axes; and a control system which drives the head by means of the handling system so as to move and orient the nozzle on the basis of the information contained in the 3D digital model.

The 3D-printing systems belonging to the first category are advantageous with respect to the traditional manual building methods since, thanks to their automation, they allow reducing the time for building the building and the relative costs. However, such systems have the drawback of allowing the building of structurally limited buildings, similar to "monoliths" since they are built with one single material, generally concrete. Therefore, these systems allow building only monolayer walls, the completion of which requires further interventions for applying on the monolayer wall the remaining completion layers envisaged in the building, such as for example, the heat insulation layers and the finishing layers (internal and external plastering).

A second category represented by the "powder bed" 3D- printing systems with jetting technique or via spraying (indirect 3D-printing technique or additive manufacturing) provides for the walls to be built by spraying or laying a binder-based liquid agent on a powder bed. These systems essentially provide for laying a generally powdered granular compound on a horizontal plane so as to form a bed or layer of powder and spraying the liquid agent on the laid layer so as to form a rigid matrix which incorporates the granules causing their setting and forming a set/hardened horizontal layer.

A jetting 3D-printing system belonging to the second category is described for example in the Italian patent application No. ITPI2005A000031. A drawback of the apparatus described in the Italian patent application No. ITPI2005A000031 is that it requires the assembling and the dismantling of the containment walls of an external container, said operations affecting labour and transportation costs. The containment walls of the container are also specifically sized on the basis of the sizes associated with the outer volume of the building and thus make the apparatus unsuitable for being used for the building of other buildings, having sizes different from those of its container. Another technical problem of the apparatus described in the Italian patent application No. ITPI2005A000031 is the need to use a relatively high amount of granular material, higher that is than the amount of material actually necessary for building the walls of the building. In fact, the apparatus provides for overlapping powdered layers equivalent in size to the entire area inside the container thus causing the complete filling of the latter. At the end of the building of the building it is thus necessary to carry out a suitable operation for emptying the non-hardened granular material present in the container, material which is in excess. This condition, if added to the supply and handling time and costs of the granular material, affects, on the whole in a non-negligible manner, the time and the costs for building the building. Furthermore, the large amount of granular material used entails an increase in the manufacturing complexities of the apparatus in structural terms since it requires an oversizing of the container and of its outer vertical uprights.

Another jetting 3D-printing system is described in the Italian patent application No. ITPI2007A000108 . This application relates to a printing apparatus which replaces the fixed outer container with a containment wall made of granular material which is progressively built by the apparatus during the building of the building. If, on the one hand, this solution allows eliminating the outer container overcoming in such manner the relative drawbacks, on the other hand it is unsatisfactory as it requires, at the end of the building of the building, both the demolition of the outer containment wall, and the removal of the powdered granular material which is progressively stored between the same and the outer peripheral portion of the built building, said operations affecting in a non- negligible manner the costs for building the building.

Furthermore, the aforementioned solutions belonging to the second category have the same limitation present in the solutions of the first category since they allow building only monolithic walls provided with one single material. Therefore, also in this case, the completion of the walls requires further interventions, for example, heat insulation layers, internal and external plastering.

US 2005/0280185 A1 describes a 3D printer for the rapid prototyping of pieces of large dimensions.

DESCRIPTION OF THE INVENTION

The object of the present invention is thus to provide a jetting 3D-printing system and method with powder bed laying for the automated building of a vertical portion of a building which overcomes the drawbacks and the technical problems described above.

This objective is achieved by the present invention since it relates to a 3D-printing system and method for the building of a building defined according to the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawings, which illustrate a non-limiting example embodiment thereof, wherein:

- Figure 1 is a schematic perspective view of a 3D- printing system for building at least one vertical wall of a building according to the present invention,

- Figure 2A schematically shows a horizontal section of a multilayer vertical wall of a building built by the 3D- printing system shown in Figure 1,

- Figure 2B schematically shows a vertical section III- III of a multilayer vertical wall of a building built by the 3D-printing system shown in Figure 1, - Figure 3 is a further schematic perspective view of the 3D-printing system shown in Figure 1,

- Figure 4 is a further top plan schematic perspective view of the 3D-printing system shown in Figure 1,

- Figure 5 is the section I-I, with parts removed for clarity, of the 3D-printing system shown in Figure 4, - Figure 6 is the section II-II, with parts removed for clarity, of the 3D-printing system shown in Figure 4,

- Figure 7 is a perspective view, with parts removed for clarity, of the 3D-printing system shown in Figure 3, - Figure 8 schematically shows a perspective view of the handling system for the vertical movement of the track,

- Figure 9 schematically shows the spray device and the handling system thereof,

- Figure 10 schematically shows the unloading device and the handling system thereof,

- Figures 11, 12 and 13 schematically show as many perspective views of an unloading device comprised in the 3D-printing system,

- Figure 14 is an exploded view, with parts removed for clarity, of a spray device comprised in the 3D-printing system,

- Figure 15 shows a detail, on an enlarged scale, of the printing head of the spray device shown in Figure 14. PREFERRED EMBODIMENTS OF THE INVENTION The present invention will now be described in detail with reference to the accompanying Figures so as to allow a person skilled in the art to manufacture it and use it. Various modifications to the described embodiments will be immediately apparent to the persons skilled in the art and the general principles described can be applied to other embodiments and applications without thereby departing from the scope of protection of the present invention, as claimed in the appended claims. Therefore, the present invention is not to be considered limited to the embodiments described and illustrated, but it is to be given the broadest scope of protection compliant with the principles and the characteristics described and claimed herein.

With reference to Figures 1, 3-7, reference numeral 1 indicates, as a whole, a powder bed 3D (three-dimensional) printing system (with jetting technique or additive manufacturing) for automatically building at least one vertical wall 100a of a building 200 partially illustrated in Figure 2.

In the following disclosure, reference will be made, without thereby losing generality, to a series of vertical walls 100a. In the schematic example shown in Figure 2, the walls 100a are arranged along a horizontal path PA having (in plan) an approximately annular shape. In the illustrated example, the annular shape of the horizontal path PA along which the vertical walls 100a extend (one after the other) is approximately rectangular with the edges conveniently rounded as shown in Figure 2a. The walls 100a can form, for example, an outer vertical peripheral portion 100 of the building 200.

It is understood that the present invention is not limited to a rectangular path PA with rounded edges, but can provide for any annular geometrical shape such as, for example, a polygonal shape, a circular shape, an elliptical shape or the like. It is also understood that the present invention is not limited neither to the number nor to the shape of the walls 100a but can be applied also for building one single wall 100a having any length and shape.

With reference to the preferred embodiment shown in Figure 1, the printing system 1 comprises a mould or formwork 2, which is arranged resting on a preferably horizontal plane PB, corresponding for example to a support base, and extends vertically from the same for a pre-established height H (Figure 5). It is understood that the height H of the formwork 2 can be conveniently varied based on the height of the vertical walls 100a to be built according to what defined in the 3D digital model.

The formwork 2 extends horizontally, preferably continuously, remaining resting on the horizontal plane PB, along the preferably annular path PA so as to form a preferably annular mould. In the illustrated example, the formwork 2 substantially has four sections or sides orthogonal to each other so as to approximately form a rectangle. The formwork 2 is structured so as to internally delimit a forming chamber 3 which reversely follows the shape of the walls 100a of the building 200 to be built.

In the example illustrated in Figure 4, the forming chamber 3 has an approximately annular horizontal section. The forming chamber 3 also has a vertical section, orthogonal to the annular path PA, substantially rectangular (Figures 5 and 6).

According to a preferred embodiment shown in Figures 1, 3, 4, 5, and 7, the system 1 also comprises an unloading device 4, which is provided with a plurality of sections or containment compartments 5 (Figures 11, 12 and 13). The containment compartments 5 are independent of and separate from each other and preferably open at the top. The containment compartments 5 are designed to contain respective granular compounds (schematically shown in Figure 10) and have at the bottom relative unloading mouths or openings 6, which communicate with the internal space of the containment compartments 5 for unloading in use, on command, the granular compounds into the forming chamber 3.

It should be specified that in the following disclosure, the term "granular compounds" means a granular mixture which is suitable for the 3D-printing with jetting technique which provides for the powder bed laying. The granular mixture can comprise, for example, an inert material and preferably, but not necessarily, one or more binder materials. The inert material is suitable for defining the aggregate with which the vertical walls 100a of the building 200 are built. The inert material can preferably be in powder. The inert material can be, for example, marble-based, rock-based, sand-based or the like. With regard to the binder material, it can conveniently be in powder. The binder material can be magnesium-based. For example, the binder material can correspond by choice to: a magnesium phosphate cement-based binder and/or a geopolymer based binder. It is understood that the present invention is not limited to the inert and binder materials described above but other embodiments can be provided with other types of inert and binder materials suitable for the 3D-printing with jetting technique. For example, the inert and binder materials can conveniently correspond to the inert and respectively binder materials described in the European patent applications No. EP3168203A1 and No. EP3210949A1, whose content (description, claims and tables) are understood completely included herein by reference.

According to a preferred embodiment shown in Figures 1, 3-7, 14-15, the system 1 also comprises a spray device 7 which is designed to spray, on command and selectively, one or more activating liquid agents made of substances that are designed to react with the granular compounds laid so as to cause the setting and/or the hardening thereof. The activating liquid agents can be made, for example, of a mixture of water and/or powdered minerals. The minerals used in the activating liquid agents can comprise for example potassium, silicates and/or similar substances. The system 1 also comprises a handling system 8, which is designed to selectively move the unloading device 4 and/or the spray device 7 inside the formwork 2, i.e. inside the forming chamber 3, along the annular path PA at least in one predetermined forward direction A1 (in the example of Figure 4 corresponding to the clockwise direction) so as to make it perform a plurality of turns in the formwork 2 along the path PA.

The handling system 8 is also designed to selectively move the unloading device 4 and/or the spray device 7 inside the forming chamber 3 of the formwork 2 along a vertical direction (orthogonal to the horizontal plane PB) over several vertical levels Li so as to be able to vary the height of the unloading device 4 and/or the spray device 7 with respect to the plane PB.

The system 1 also comprises an electronic control system 9 (Figure 4) configured to selectively control, by means of the handling system 8, the movement of the unloading device 4 and/or the movement of the spray device 7 along at least two corresponding axes X, Y shown in the accompanying Figures. The electronic control system 9 is configured to selectively control, by means of the handling system 8, the unloading device 4 and/or the spray device 7 along the annular path PA.

According to the exemplifying embodiment shown in the accompanying Figures, the spray device 7 is separate from the unloading device 4. According to the exemplifying embodiment shown in the accompanying Figures, the handling system 8 is designed to move the spray device 7 along the annular path PA independently of the unloading device 4 and vice versa. The electronic control system 9 is configured to control the movement of the unloading device 4 independently of the movement of the spray device 7 along the annular path PA. In other words, the unloading device 4 and the spray device can be moved along the annular path PA independently of one another.

Preferably, the movement control provides for the spray device 7 to follow the unloading device 4 along at least the forward direction A1.

The electronic control system 9 is also configured to control the vertical movement of the unloading device 4 and/or of the spray device 7 (along the axis Z in Figure 1) by means of the handling system 8 so as to selectively position them over several levels Li (i variable between 1 and K) having pre-established heights and associated with the respective turns or layers Si. The electronic control system 9 is also configured to control the unloading device 4 so as to form, during each turn inside the formwork 2, a horizontal granular bed or layer Si (i variable between 1 and K) of granular compounds. In the illustrated example, the horizontal granular bed or layer Si has an annular shape on the plane PB. The granular layer Si laid has a width Lgl transverse to the forward direction A1 corresponding approximately to the width of the internal forming chamber 3. The granular layer Si has a predetermined thickness (measured vertically), preferably constant along the annular path. The granular layer Si is composed of a plurality of horizontal stratiform granular strips Vi (i comprised between 1 and N) made of granular material. In the illustrated example, the stratiform granular strips Vi are annular (concentric). In the illustrated example, the stratiform granular strips Vi of the granular layer Si are arranged on top of the underlying layer Si-1. In the illustrated example, the stratiform granular strips Vi of the granular layer Si after the completion of the turn have an annular shape (in plan). In the illustrated example, the stratiform granular strips Vi are arranged on the respective annular strips that form the underlying layer Si-1. The vertical overlapping of the granular strips Vi of the granular layers Si causes the composition/forming on the wall 100a of a plurality of vertical layers that can be conveniently made with materials different from each other.

The electronic control system 9 is also configured to control the spray device 7 during the movement so as to selectively spray the granular strips VI with the activating liquid agents, so as to cause the hardening/setting thereof on the basis of the 3D digital model.

The electronic control system 9 is also configured not to spray the activating liquid agents on one or more granular strips Vi on the basis of the structure of the 3D model, so as not to cause the setting/hardening thereof.

It is understood that the spray device 7 can be controlled so as to selectively spray the activating liquid agents only on some longitudinal portions (not illustrated) of the annular strips Vi along the path PA and leave the remaining portions or sections, "not sprayed" and thus in the granular state (in powder) so as to create internal cavities and/or through-openings in the wall 100a. In use, the granular material of the annular strips Vi which has not been sprayed and thus not hardened by the activating liquid agents, i.e. has remained in powder, can be conveniently removed for forming the internal cavity or the through- opening in the wall 100a.

The Applicant has found that the use of the unloading device 4 and of the spray device 7 described above has the technical effect to allow the building of multilayer vertical walls, i.e. formed of a series of layers that lie on vertical planes parallel to each other, in which each of the vertical layers can have a structure and composition different from the other adjacent vertical layers. This allows building "complete" multilayer walls, i.e. composed of all the layers envisaged in the building according to what designed in the 3D model.

In other words, it is possible to completely build a "finished" wall 100a provided with any number, type and shape (in vertical) of layers such as for example layers composed of materials that have a structural function (bearing structural functions), layers having heat and/or acoustic insulation functions, layers having a surface finishing function. Thanks to the combined and independent action of the unloading device and of the spray device described above it is possible to selectively set/harden the layers composing the wall 100a, and to conveniently form two outer vertical layers of the wall 100a (which remain in contact with the formwork 2 during the building), which remain in a granular state (in powder). This condition allows increasing the simplicity of decoupling the formwork 2 from the wall 100a and simplifying the cleaning of the latter since the granular elements do not remain attached thereto being in powder.

A further technical effect is being able to stop the spraying and thus make sections of stratiform granular strips not sprayed by the activating liquid. The sections of stratiform strips not sprayed remain in the powder/granular state and allow forming on the wall (by a subsequent removal of the granular materials) internal cavities or through- openings corresponding for example to windows or doors. The internal cavities can thus define interspaces/ducts and can be made on the basis of the interspaces/ducts (generally made manually on the wall) envisaged in the heating and wiring systems of the building conveniently designed and included in the 3D model.

With reference to the preferred embodiment shown in Figures 1, 3-10, the formwork 2 is formed of two containment walls 2a which extend vertically from the horizontal plane PB and are arranged facing each other. The two walls 2a extend horizontally along the path PA, parallel to each other at a mutual distance, transverse to the forward direction Al, corresponding approximately to the width Lgl of the internal forming chamber 3. The two containment walls 2a are conveniently modular so as to be easily dismounted/assembled. Conveniently, the walls 2a can comprise a plurality of panels 2c (Figure 7), for example rectangular, which are coupled to each other and are structured to be, in use, easily assembled/dismounted/removed . Preferably, the formwork 2 also comprises a support structure of the panels 2c which, in the example illustrated in the accompanying Figures, is defined by a modular scaffolding 10 of the type that can be easily assembled/disassembled . It should be specified that the modularity of the formwork 2 deriving from the combined use of the scaffolding 10 and of the panels 2c has the technical effect of freeing the system 1 from the possibility of making one single shape/size of the vertical portion of the building 200. This increases the versatility of the system 1 since it is can be used for building buildings provided with vertical walls having different shapes and sizes.

The scaffolding 10 is also advantageous because on the one hand it allows simplifying the internal/external cleaning and post-production activities, and on the other hand it can be conveniently used by the operators as walkable staging for the assembling of other building components/elements of the building 200, such as for example, window and door frames, downspouts, railings, roof, etc. With reference to an embodiment shown in Figures 4, 7,

8, and 10, the handling system 8 can comprise: a sliding track 12, which extends along the path PA inside the forming chamber 3 on an approximately horizontal plane, and motorized slides 13, which are firmly associated with/coupled to the spray device 7 and the unloading device 4. The motorized slides 13 are mounted on the sliding track 12 for moving on command the spray device 7 and the unloading device 4 along the path PA in the forward direction A1.

In the illustrated example, the motorized slides 13 are preferably operated electrically, are firmly coupled to the spray device 7 and to the unloading device 4, and are provided with motorized wheels which are coupled to the sliding track 12. The motorized slides 13 are controlled in use by the electronic system 9 so as to move the spray device 7 and the unloading device 4 along the path PA in the direction A1 (clockwise in Figure 4).

It is understood that additionally or alternatively, the electrically operated motorized slides 13 can be controlled in such a way to move the spray device 7 and the unloading device 4 along the path PA also in a direction opposite the direction A1 (anti-clockwise in Figure 4).

With reference to an embodiment shown in Figure 8, the track 12 can comprise a pair of rails which extend continuously coplanar and parallel to each other along the annular path PA and are each arranged adjacent a relative wall of the formwork 2.

In the illustrated example, the rails of the track 12 are supported by a frame 14 preferably resting on the horizontal plane PB. The frame 14 comprises a structured mechanism so that, in use, it is operated by the handling system 8 for vertically moving the lying plane of the track 12 so as to control the height, i.e. the level Li of the spray device 7 and of the unloading device 4 with respect to the horizontal plane PB. According to a possible embodiment shown in Figure 8, the frame 14 can comprise vertical columns 15 which are coupled to the track 12 for supporting it and handling members 34 for vertically moving the track 12 with respect to the plane PB keeping it horizontal by means of said columns 15. The handling members 34 can comprise for example mechanical screw jacks (Figure 8) or could comprise motorized slides that support the track 12 and are mounted movable on the columns 15 for moving vertically on command, from the bottom upwards and vice versa. It is understood that the present invention is not limited to a handling system formed of the frame 14 and/or of the handling member 34 but can comprise any other device/apparatus which is capable of moving vertically, in a controlled manner, the track 12 keeping it approximately horizontal, such as for example an electric actuator or the like.

With reference to Figures 11-13, the unloading device 4 comprises a hopper 35 provided at the bottom with an unloading mouth 36 and comprising internally a series of vertical bulkheads 37 that divide the internal space of the hopper 35 in said containment compartments 5. The bulkheads 37 also divide at the bottom the unloading mouth 36 in the lower openings 6 of the containment compartments 5.

The unloading device 4 also comprises at the bottom a plurality of plate-like elements 20 designed to close/open the lower openings 6 of the containment compartments 5. According to an exemplifying embodiment shown in Figure 13, the unloading device 4 comprises a pair of plate-like elements 20, for example blades opposite and parallel to each other. The plate-like elements 20 can have, for example, an approximately oblong rectangular shape and are structured to be selectively moved with respect to each other between a closing position of the openings 6 of the unloading mouth 36 and an opening position of said openings 6, and vice versa. The plate-like elements 20 can be operated between the closing and opening position by one or more motorized members 38, for example electric motors which are controlled by the electronic system 9 and can be mechanically connected to the plate-like elements 20 through transmission/operating mechanisms. In use, the electronic system 9 can control the movement of each plate-like element 20 so as to control/adjust the amount of granular compounds unloaded from the containment compartments 5 through the relative openings 6. The adjustment of the opening/closing of the pair of plate-like elements 20 causes the simultaneous opening/closing of the containment compartments 5. According to a possible alternative embodiment (not illustrated) the openings 6 of the containment compartments

5 of the unloading device 8 are selectively controlled by respective plate-like elements 20 so as to adjust the amount of granular compound unloaded from each containment compartment 5. Each of the plate-like elements 20 is thus arranged on a relative opening 6 and can be selectively and independently operated with respect to the others for controlling the opening/closing of the opening 6. The movement of the plate-like element 20 present in the opening

6 of a containment compartment 5 can thus be controlled by the electronic system 9 on the basis of the granulometry (size) of the granular compound contained in the containment compartment 5. In this manner, it is possible to differ in a controlled manner the amount of granular compounds unloaded from each containment compartment 5 with respect to the other containment compartments 5. Hence, the making of a horizontal granular layer Si is ensured which has the same vertical thickness along the entire width upon the varying of the granulometry of the granular compounds forming the strips.

With reference to the preferred embodiment shown in Figures 14-15, the spray device 7 comprises: a box-type frame 21, for example, having the shape of a parallelepiped, a series of tanks 22 which are arranged inside the box-type frame 21 and are designed to contain respective activating liquids, and a printing head 23 which is hydraulically connected to the tanks 22 through a hydraulic system 40 for receiving the activating liquids and comprises a plurality of nozzles (not illustrated) through which it selectively expels the activating liquids so as to spray them on the layer SI.

According to an exemplifying embodiment, the tanks 22 are conveniently provided at the top with loading openings 22a from which loading tubes 22b extend vertically upwards designed in use to be used for pouring the activating liquids into the tanks 22.

According to an exemplifying embodiment, the printing head 23 is arranged in the box-type frame 21 under the tanks 22. The hydraulic system 40 comprises a series of ducts 24 which connect the printing head 23 to the tanks 22.

According to an exemplifying embodiment, the printing head 23 can comprise an upper plate 23a and a lower plate 23b, which are mutually coupled sealingly and internally delimit a plurality of containment chambers 25. Each containment chamber 25 is hydraulically separate from the adjacent containment chambers 25 by internal partition walls 26 and is hydraulically connected, by a relative internal hydraulic branch to a duct of the hydraulic system 40 through which it receives the activating liquid present in the tank 22. According to an exemplifying embodiment, the containment chambers 25 are arranged in the printing head 23 according to a matrix distribution formed of at least two lines, in each of which the containment chambers 25 are arranged in a row one after the other, alongside the containment chambers 25 of the other line, so as to form therewith a plurality of columns.

In the lower plate 23b, inside each containment chamber 25, a plurality of nozzles is installed, said nozzles being selectively controlled by respective electrically controlled operating members (not illustrated). Preferably, the nozzles are installed in respective through-openings obtained on the lower plate 23b and are in hydraulic communication with the relative containment chamber 25. The operating members can comprise solenoid valves and be housed in respective seats preferably obtained on the upper plate 23a inside the relative containment chamber 25. Preferably, the nozzles can be arranged at a distance from each other of approximately 3 mm. Preferably, the spray device 7 is modular, i.e. the elements of which it is composed can be easily assembled/disassembled . A technical effect of the modularity is represented by the fact that in use, it is possible to compose and thus to configure the spray device 7, each time, on the basis of the number of stratiform granular strips Si of the granular layer, of the type of activating liquids and of the width Lgl of the granular layer Si. To this purpose, it is possible to vary the number of tanks 22 and/or the size of the printing head 23 (width), an/or the configuration of the internal chambers 25 at the printing head 23 depending on the number of strips of the layer SI, of the type of activating liquids and of the width of the layer SI.

With reference to Figures 1, 3 and 7, the printing system 1 can also conveniently comprise a loading system designed to selectively load the granular compounds in the containment compartments 5 of the unloading device 4.

In the illustrated example, the loading system comprises one or more loading stations 16, each of which comprises a loading apparatus 18 which is connected through a series of ducts to a silo or tank 19 which in turn contains the granular compounds. Preferably, the silo or tank 19 can comprise the different granular compounds, i.e. inert materials and/or the binder materials separated into as many containment compartments.

According to an exemplifying embodiment, the loading apparatus 18 is arranged on top of the formwork 2 so as to face the containment compartments 5 of the unloading device 4 (when it is in a loading position) and is structured so as to receive in input the granular compounds contained in the tank 19. The loading apparatus 18 can be structured in such a way that, under the control of the electronic control system 9, it doses and/or mixes the granular compounds to be loaded in each containment compartment 5 of the unloading device 4. To this purpose, the loading apparatus 18 can be provided with loading ducts which in use align with the corresponding underlying containment compartments 5 when the unloading device 4 is arranged in a loading position in the loading station.

With reference to Figures 1, 3 and 7, the printing system 1 can also conveniently comprise a loading system 30 designed to selectively load the activating liquids in the tanks 22 of the spray device 7. In the illustrated example, the loading system 30 comprises one or more loading stations 31, each of which is provided with a loading apparatus 32 which is connected by means of a series of ducts to at least one silo or tank 33 which contains the activating liquids. Preferably the silo or tank 33 can comprise the various activating liquids separated in as many internal containment chambers (not illustrated).

According to an exemplifying embodiment, the loading apparatus 32 is placed on top of the formwork 2 so as to face the containment tanks 22 of the spray device 7 and is structured in such a way to receive in input the activating liquids contained in the tank 33. The loading apparatus 32 can be structured in such a way that, under the control of the electronic control system 9, it selectively loads the activating liquids in the tanks 22 of the spray device 7.

To this purpose, the loading apparatus 32 can be provided with loading ducts which in use align with the tubes 22b of the underlying tanks 22 when the spray device 7 is arranged in the loading position in the loading station 31.

In use, the 3D-printing method for building the vertical portion 100 of the building 200 comprises the following steps.

A step is provided for defining/designing the 3D digital model which defines the vertical walls 100a of the vertical portion 100 of the building 200. The 3D digital model comprises all the information/technical data relative to the structure and to the composition of the vertical walls 100a. In particular, the 3D digital model can comprise information/technical data concerning the multilayer wall, i.e. the various vertical layers which compose it and their composition, i.e. the activating granular/binder/liquid materials. The three-dimensional digital model can also comprise information/technical data concerning through- openings and/or cavities and/or separation lines present in the vertical portion 100. It is understood that the separation lines can delimit walls 100a in the vertical portion 100 which are separate and distinct from the other walls of the vertical portion 100.

A step is also provided for building the formwork 2. This step can conveniently comprise the manual assembling of the scaffolding 10 and of the panels 2c so as to form the annular walls 2a of the formwork 2. It is understood that the building of the formwork 2 is carried out on the basis of the data/information contained in the 3D digital model.

A step is also provided for configuring the spray device 7 on the basis of the 3D digital model and for building it on the basis of the configuration.

A step is also provided for configuring the unloading device 8, and in particular the containment compartments 5 thereof on the basis of the 3D digital model and for building it on the basis of the configuration.

The step is also provided for installing: the handling system 8 (i.e. of the frame 14, of the track 12, the motorized slides 13, of the handling member 34), of the unloading device 4, of the spray device 7, of the electronic control system 9 and of the tanks 19 and 33 containing the inert materials, the binders, and the activating liquids.

A step is also provided for loading/storing in the electronic control system 9 the 3D digital model of the vertical walls 100a forming the vertical portion 100 to be built. The electronic control system 9 establishes the sequential operations to be implemented, during the building of the vertical portion 100, for controlling: the handling system 8, the unloading device 4 and the spray device 7, on the basis of the information/data contained in the 3D digital model. The control system 9 can also conveniently control the operations carried out in the silos 19 and 33 (mixing of the liquids and of the solids) and/or the loading apparatuses 30 and 32 during the loading operations of the unloading device 4 and of the spray device 7.

In the initial step, i.e. before making the unloading device 4 and the spray device 7 perform the first turn in the forming chamber 3 for forming the first layer SI on the horizontal plane PB, the track 12 is positioned by the electronic control system 9 by means of the handling system 8 at a first pre-established level LI (first height).

In the initial step, the electronic control system 9 moves the unloading device 4 by means of the handling system 8 in the relative loading station 16, and operates the loading apparatus 18 so as to selectively load the granular compounds in the relative containment compartments 5 of the unloading device 4 so as to fill them according to pre- established doses. It is understood that the doses can be established on the basis of the width/height/thickness dimensions of the respective vertical layers of the walls to be built and of the "turn" to perform. It is also understood that the granular compounds are loaded in the containment compartments 5 on the basis of the relative compositions of the vertical layers Ti of the walls 100a of the vertical portion 100.

In the initial step, the electronic control system 9 moves the spray device 7 by means of the handling system 8 in the relative loading station 30 and operates the loading apparatus 32 for loading in a selective and dosed manner, according to the amount established, the activating liquids in the relative tanks 22 of the spray device 7.

It is understood that the activating liquids are loaded in the tanks 22 on the basis of the composition and structure of the vertical layers Ti which form the walls 100a of the vertical portion 100.

It is also understood that the present invention is not limited to the loading of the granular compounds formed of the mixture composed of binders and inert materials in the containment compartments 5 of the unloading device 4.

According to an embodiment alternative to the one described above, the binders can be liquid and mixed with the activating liquids, so as to be sprayed by the spray device 7. The electronic control system 9 controls by means of the handling system 8 the movement of the unloading device 4 along the annular path PA and in the direction A1 so as to form, during the first turn, the layer Si=Sl on the horizontal plane PB associated with the first level Li=Ll. The layer SI formed during the first turn has an annular shape and comprises a series of annular stratiform granular strips Vi and has a predetermined thickness. In this step, the electronic control system 9 can control the forward speed of the unloading device 4 and/or the amount of granular compounds unloaded from the containment compartments 5 on the basis of the vertical thickness of the layer SI to be made. According to an embodiment, the adjustment of the amount of the granular compounds unloaded from the containment compartments 5 can be carried out controlling the movement of the pair of plate-like elements 20 (shown in Figure 13).

According to the embodiment variant, the selective control of each of the openings 6 of the containment compartments 6 is provided by a relative plate-like element 20 so as to adjust the amount of the granular compounds unloaded from each of the containment compartments 5.

The electronic control system 9 controls by means of the handling system 8 the movement of the unloading device 4 along the annular path PA in the direction A1 so as to form, during the first turn, the layer SI on the horizontal plane PB associated with the first level Li=Ll. The layer SI formed during the first turn has an annular shape and comprises a series of concentric annular stratiform granular strips Vi (i comprised between 1 and N) associated with the layers of the vertical portion 100 and has a predetermined vertical thickness.

The electronic control system 9 also controls, by means of the handling system 8, the movement of the spray device 7 (with respect to the reference axes X and Y) along the annular path PA in the direction A1 so as to follow the unloading device 4. The electronic control system 9 controls the spray device 7, so as to selectively spray the activating liquids on the annular strips Vi which form the layer SI on the basis of the 3D digital model. In this step, the electronic control system 9 selectively controls by means of the nozzles the activating liquid on the sections of stratiform granular strips Vi depending on the data/information contained in the 3D digital model. It is understood that the spray device 7 can spray with a certain pressure.

To this purpose, the containment chambers 25 can be constantly kept at a predetermined pressure. To this regard, it should be specified that the containment chambers of the printing head 23 can contain activating liquid (s) composed of different formulations and materials which give, to each liquid, specific characteristics also very different from each other. Such characteristics can correspond to volume, density, viscosity, surface tension, of the liquid. The electronic control system 9 is thus capable of controlling the spray device 7 on the basis of the characteristics of each containment chamber 25 and of the liquid present therein. Furthermore, the electronic control system 9 is designed to control the pressure with which the liquid is expelled from the containment chamber 25 through the nozzle. Such pressure can be selectively controlled/varied on the basis of the characteristics of the stratiform stripe Vi to be set/hardened.

Once completed the first turn, the electronic control system 9 also controls, by means of the handling system 8, the vertical movement of the track 12 so as to arrange it at a second level Li=L2 associated with a pre-established height higher than the first level LI (L2>L1).

The electronic control system 9 again controls by means of the handling system 8 the movement of the unloading device 4 so as to form a new layer S2 on top of the layer SI and contextually the spray device 7 so as to selectively spray the stratiform granular strips Vi of the layer S2 previously set/hardened by the activating liquids.

The electronic control system 9 repeats the controls described above on the handling system 8, on the unloading device 4 and on the spray device 7 so as to implement a plurality of turns, moving vertically, at the end of each turn, the track 12 over a new level until reaching the height

H of the formwork 2.

The system and the method described above have the advantage of reducing the amount of granular material necessary for building the walls. In particular, the use of a formwork sized on the basis of the wall to be built, i.e. substantially having the same dimensions, and in particular the same length, allows using during the method an amount of material corresponding to the amount actually necessary. This eliminates the need, on the one hand, to manage high amounts of material and to thus limit the costs for the management and purchase of said material, and on the other hand the need to have to remove the exceeding material following the building of the wall.

Another advantage of the system described above is the fact that thanks to the selective laying of the granular material carried out by the unloading device and by the selective activation thereof obtained by means of the spray device, it is possible to build any type of wall in terms of number of layers of different material, of shapes, of internal cavities and of openings. In other words, the selective laying of the granular material in overlapped stratiform strips together with the selective activation of the materials composing the granular strips so as to harden them, allows building multilayer walls of high complexity without any limitations of shape, of number of layers, of type of material and thus allows building complete and finished walls. It is finally apparent that modifications and variants can be made to the system and to the method described and illustrated above without thereby departing from the scope of the present invention. For example, according to a different embodiment (not illustrated) the formwork 3 instead of having a closed annular shape shown in the accompanying Figures, can extend along an open (not closed) path and thus have the two opposite longitudinal ends open, i.e. not connected to each other. The open path can thus follow the shape of a single open wall of any type, i.e. rectilinear, or curvilinear, or the like. In this embodiment, the system controls the unloading device 4 and the spray device 7 analogously to what described above. In this embodiment, the system differs from the one described above which provides for an annular formwork 2 and the movement of the unloading device 4 and the spray device 7 in the formwork 2 so as to perform turns, due to the fact that the movement of the unloading device 4 and of the spray device 7 is linear and is carried out between the two opposite ends of the formwork along a forward direction or two opposite forward directions, in an alternated manner.