WO2011021080A2

WO2011021080A2 - Method and apparatus for quick production of a conglomerate building structure

Info

Publication number: WO2011021080A2
Application number: PCT/IB2010/001835
Authority: WO
Inventors: Enrico Dini
Original assignee: Monolite Uk Ltd
Priority date: 2009-07-24
Filing date: 2010-07-26
Publication date: 2011-02-24
Also published as: IT1395207B1; WO2011021080A3; ITPI20090095A1

Abstract

A method and an apparatus to provide a building structure (100) in conglomerate material. The method provides a step of modelling by CAD the structure and of generating cross-sections comprising solid areas and empty areas corresponding to solid parts and empty parts of the structure (10) in the cross-sections. The method provides then moulding the structure (10) by prearranging a printing area (70) and a material mobile depositing unit (200) that covers horizontally the printing area and moves according to a prefixed vertical pitch. The mobile depositing unit (200) deposits a first uniform horizontal layer of granular material thick as the pitch and spreads binding agent only on the solid areas of the first layer of granular material. Then, a further step is provided of distributing a second layer of granular material and a step of pressing the granular material with rollers (300). Such steps are then repeated up to completion of the last layer of the structure (100). Then, the granular unbound material is removed. In particular, the step of pressing with rollers (300) provides a pressure intensity comprised in a predetermined range that causes the pressing step not only to make level and regular the surface of deposited material, but provides a variable pressure energy, which is transmitted to the layer located underneath. In particular, the layer located underneath not yet hardened, in the zones where the liquid component was spread, contains a mixture of granular material, of the solid component of the binding agent and of the liquid component of the binding agent. This energy allows the mixture to be compressed and then released giving rise to an elementary "moulding step", supplying to the mixture a "reticulation energy" that assists the production of the crystal lattice of the two-part binding agent and of the conglomerate granular material. This way, the final solid composite material is very compact and homogeneous with subsequent good structural resistance.

Description

TITLE

METHOD AND APPARATUS FOR QUICK PRODUCTION OF A CONGLOMERATE BUILDING STRUCTURE

DESCRIPTION

Field of the invention

The present invention relates to the building industry and, in particular, it relates to a method for quick and automatic production of conglomerate structures such as buildings or other construction works.

Furthermore, the invention relates to a device controlled by a computer for quick production of the above described conglomerate building structure.

Hereinafter, the terminology "building structure" or "building" is used for defining a conglomerate structure that is fit for habitation, such as a dwelling, or also an article of the building industry, such as a monument, a sculpture, an article of civil engineering or of construction engineering.

Description of the prior art

A method and an apparatus are known for constructing automatically conglomerate structures, in particular buildings, as described in WO2006100556.

In particular, the apparatus is controlled by a computer and has a three axes linear manipulator according to three orthogonal directions of which one vertical; it is adapted to deposit in alternation a layer of granular material and a layer of liquid binding material, in particular epoxy resin or polyurethane, creating a conglomerate material only in predetermined points of the layer. The whole process is carried out within containing walls that define a closed perimeter.

Such method has the drawback of requiring an assembly operation of the containing walls, before depositing the many layers for making the conglomerate structure, a disassembly of the walls after hardening the structure, causing costs of manual work and of transportation owing to the weight and of the encumbrance of the walls. Furthermore, the containing walls are sized according to a maximum volume of the structure that depends on what has to be constructed inside, with the consequence that the volume of granular material used is often much more than necessary, with higher costs both for the supply and for handling and removing the unused granular material at the end of the production process.

It is useful, furthermore, that, during the construction process and especially at the end of it, the containing walls are subject to forces of hydrostatic type of the granular material that have to be biased by the reinforcing framework of the walls, giving a high complexity and heavy sizing not only to the walls but also to such framework of the apparatus.

Such a method has also the drawback of using two-part organic resins of epoxy or polyurethane type as binding material, that are characterised by a high cost and by a low environmental compatibility both under the aspect of the production, and of the disposal, as well as of toxicity in case of fire or prolonged contact.

A further drawback is the high complexity and cost of the spraying heads, owing to the precise dosage ratio required by the resins and the need of accurate and frequent maintenance, cleaning and periodic change of the parts of the spraying heads where the two components contact each other.

Such method has then the drawback that the conglomerate material obtained by using the resins is characterised by a low value of the modular elasticity portion causing a high deformability of the parts of the structures obtained that are subject to flexional and tension loads.

US5204055 and US2008001331 disclose construction techniques of building structures by means of 3D printing for depositing and printing alternate layers of granular material up to obtaining a plurality of structural portions, as described in WO2006100556 and WO2009/037550. In particular, US2008001331 describes a stereo-lithography method to provide structures, without shells or containing walls. However, this method allows only to provide small articles, since otherwise in the printing zone a huge amount of unbound granular material would be created, which can be handled in a very difficult way.

WO2009037550 introduces, furthermore, a pressing roller that acts for all the width of the printing area and is adapted to make level and pressed the granular material in a uniform way. A roller that extends transversally for all the width of the printing area cannot, however, apply a uniform compression on each zone of the printing zone. As a consequence, a high pressure can damage some parts of the structure, and zones subjected to a not enough compression can jeopardize the stiffness of the material.

WO2006/100556, which discloses a method and apparatus for automatically building conglomerate structures, provides conglomerate structures by a 3D moulding process that operates in a closed perimeter, typically taking as binding agent epoxy resin or polyurethane. In this case, the structure is made directly 'in situ' in a single working session, from the foundations to the top of the building.

WO2009/037550, which discloses an improved method for automatically producing a conglomerate structure and an apparatus therefor, provides similarly a process for making conglomerate structures by a 3D moulding, but provides also making a boundary shell to be disposed of, using a mixture of sand pre-mixed to metal oxides as granular material and a saline solutions as liquid component.

This solution introduces the advantage of eliminating the use of containing walls and the use of organic substances, that are expensive and inflammable, as binding material. Even in this case, the structure is made directly 'in situ' in a single working campaign, from the foundations to the top of the building.

A common limit of the two cited documents is that the final size of the building is correlated to the size of the machinery that has to envelope all the structure.

Another common limit is that on each printed layer the ratio between the area of the bound cross-sections and the total printing area is normally very low, on average under 30%. Consequently, the amount of granular material that it is necessary to use to obtain the whole article is high and correspondingly high is the material that has to be recovered at the end of the printing cycle.

Another common limit is the impossibility of remedying to possible defects owing to wrong operations during the production, which can affect the static resistance of all the building.

Another limit is the method of combination of the granular material and of the binding agent. The combination of the granular material with the binding agent obtains a solid of crystal type. However, without an appropriate mixing action, which as well known generates a mixing enthalpy, the reaction of reticulation and crystallization is incomplete. This mixing action is for example the action of stirring a common concrete which gives to the material a full crystallization at hardening and then a good structural resistance of the hardened material.

Without this mixing action the granular material combined to the binding agent provides a tendentially porous and friable solid material.

Summary of the invention

It is then a feature of the present inventionjo provide a method for quick production of conglomerate structures that does not limit the final size of the building product.

It is another feature of the present invention to provide a method for quick production of conglomerate structures by activating a cross linking process of the binding material with the granular material in order to obtain a material with high structural resistance.

It is a particular feature of the present invention to provide a method for quick production of conglomerate structures that makes it possible to obtain structures of a desired dimension, i.e. independently from the size of the printer, in a much quicker and not expensive way.

It is also a feature of the present invention to provide a method for quick production of conglomerate structures for reducing the amount of granular material that it is necessary to obtain the whole article and therefore the amount of material that it is necessary to recover at the end of the printing cycle.

It is another particular feature of the present invention to provide a method for quick production of conglomerate structures for remedying to possible defects owing to wrong process operations during the production of the structure.

It is further particular feature of the present invention to provide a method for quick production of conglomerate structures that does not require making a shell and a containing perimeter to dispose of, simplifying the steps necessary to the construction of the final structure.

It is another particular feature of the present invention to provide a method for quick production of conglomerate structures that makes it possible to use the printing area in an optimized way, increasing significantly the ratio between solid areas and total area and multiplying the production rate of the machinery.

It is a further feature of the present invention to provide an apparatus for quick production of conglomerate structures that achieves the same objects.

It is another feature of the present invention to provide an apparatus for quick production of conglomerate structures that makes it possible to obtain objects and structures with free shape without limits with respect to the final size.

It is a further feature of the present invention to provide an apparatus for quick production of conglomerate structures that makes it possible to use other types of material that after reaction with a binding agent form a solid composite material.

These and other objects are achieved through a method for quick production of a conglomerate building structure comprising the steps of:

- modelling in a computer-aided way a building structure model by a CAD software;

- sectioning said building structure model with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross- sections of said building structure model, each cross-section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of said building structure in said cross-sections, said cross- sections sorted from below towards the above;

- printing said building structure, said printing step comprising the further steps of:

- prearranging a printing area and a material mobile depositing unit, so that said mobile depositing unit can span horizontally said printing area and can move according to said prefixed vertical pitch,

- depositing, by said mobile depositing unit within said printing area, a first uniform horizontal layer of granular material of thickness corresponding to said prefixed vertical pitch, wherein said granular material contains a powder solid component of a two-part binding agent;

- spraying a predetermined amount of a liquid component of said two- part binding agent by said mobile depositing unit on said first layer of granular material only at said solid areas of a first cross-section of said structure;

- raising vertically said mobile depositing unit with respect to said fixed frame according to said prefixed vertical pitch;

- depositing a second uniform horizontal layer of granular material onto said first layer;

- pressing said second layer;

- spraying a predetermined amount of binding agent on said second layer only at said solid areas of a second cross-section consecutive to said first cross-section of said structure;

- repeating for further layers the step of depositing granular material, of spraying a predetermined amount of binding agent, of raising vertically said mobile depositing unit and of pressing up to completion of a last layer of said building structure;

- removing the unbound granular material, obtaining said building structure,

wherein said step of pressing occurs by a pressing intensity set between,01 and 1 Kg/cm², preferably between 0,05 and 0,5 kg/cm².

This way, said step of pressing with a pressure intensity comprised within said range causes the pressing step not only to make level and regular the surface of deposited material, but provides a pressing energy, which is transmitted to the layer located underneath that, in the zones where the liquid component was spread, contains a mixture of granular material, of the solid component of the binding agent and of the liquid component of the binding agent. This energy allows the mixture to be compressed and then released giving rise to an elementary "moulding step", supplying to the mixture a "reticulation energy" that assists the production of the crystal lattice of the two-part binding agent and of the conglomerate granular material. This way, the final solid composite material is very compact and homogeneous with subsequent good structural resistance. This way, it is possible to provide structures of a desired dimension, i.e. not responsive to the size of the printing zone, in a way quicker and not expensive with respect to the prior art. In particular, differently from the case of making a whole building "in situ", as described in WO2006100556 and WO2009/037550, but splitting it into portions of predetermined size, and manufacturing the portions directly in the building yard, in order to make a structure with desired shape and size simply assembling the various structure portions, previously modelled and built, in a selected building area without containing and supporting walls or shells.

Advantageously, the following further steps are provided:

- modelling structure portions, said step of modelling comprising the further steps of:

- splitting into portions said building structure model by means of division surfaces in order to define a plurality of said structure portions, said structure portions being separated from each other by said division surfaces;

- providing for each structure portion, at said division surfaces, an assembling interface, such that adjacent division surfaces of adjacent structure portions make up a shape matching with each other;

- sectioning each structure portion with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross- sections of each structure portion, each cross-section comprising solid areas and hollow areas, corresponding to the solid parts and to the hollow parts of said structure portion in said cross-section, said cross-sections sorted from below towards the above;

- printing said structure portions;

- assembling said plurality of structure portions by connecting to each other said assembling interfaces that provide said matching shape, in order to construct said building structure corresponding to said building structure model.

Advantageously, said division surfaces between said structure portions are horizontal planes. In addition, vertical division surfaces or oblique division surfaces can be used. This way, structure portions are obtained of suitable size ideal for stereo lithography, without using shells or containing walls to avoid a large production of masses of still loose granular material around the article.

Furthermore, the sectioned surfaces can provide vertical stairs-like divisions of variable thickness at said discontinuities to obtain relatively simple structure portions. Normally, for sectioning the structure the thickness of each portion has to be in any case proportioned to its maximum horizontal size avoiding too thin portions and preferring making not tall structure portions, in particular substantially that can be inscribed in a cube or a sphere.

In particular, said step of modelling provides a step of creating a recess in each structure portion in order to obtain hollow structure portions defined by walls with a determined thickness.

Advantageously, said step of modelling provides the step of creating in said walls a plurality of longitudinal grooves substantially parallel to each other made in said thickness, said longitudinal grooves being substantially continuous with neighbouring structure portions, said grooves adapted to house inserts in order to provide said assembling interface with matching shape.

In particular, said inserts selected from the group comprised of: reinforcement iron bars, seal elements, connection flanges and/or connection pins.

Advantageously, each lower seal element is a flat and closed seal element that covers the outer perimeter of the wall of a relative structure portion. Preferably, said lower seal element has fixed width and is internally tangential to the longitudinal frameworks present in that section, in particular said lower seal element comprises holes set to house reference pins for correct mechanical matching of the structure portion with a neighbouring structure portion.

In particular, a step is provided of prearranging stiffening pins in said lower seal elements and/or in said upper seal elements, said step of prearranging can be done before or after said step of building steps of the structure portions.

Preferably, said plurality of lower seal elements that is obtained by said steps of repeating is distributed in a optimised way on a working surface, in particular by a step of two-dimensional coupling obtaining at least one file in two-dimensional CAD format, that can be immediately carried out by numerical control cutting machine tools.

Advantageously, said step of making said upper seal elements comprises the modelling steps said seal elements on the upper surface of each structure portion in such a way that it is suitable for follow the outer perimeter of the structure portion.

Advantageously, said lower seal elements and said upper seal elements are made of a material selected from the group comprised of: aluminium, steel, composite material, or a cloth of textile fibres in any case which are resistant to tensile stress.

Advantageously, said lower seal elements and said upper seal elements are made by a numerical control cutting machine tool of the laser or water jet type capable of keeping one plane form during manipulation.

Advantageously, said step of making said support base and said base seal elements for correct mounting of said structure, provides the steps of: - dividing into a plurality of parts of suitable size said support base or said base seal elements obtaining at least one file in two-dimensional CAD format;

- executing said file by means of numerical control cutting machine tools to make said plurality of parts;

- assembling said plurality of parts in order to obtain said support base or said base seal elements.

Preferably, said step of modelling provides a step of creation on a lower surface of each structure portion of one or more boundary recesses of thickness and depth that is adapted to determine a boundary connection edge, which forms a matching reference shape between neighbouring structure portions.

Advantageously, said step of printing said structure portions provides a preliminary step of distributing said structure portions in the printing area in order to exploit as far as possible the printing zone, in order to obtain a maximum area of the solid portions with respect to blank portions. In particular, said step of distributing comprises the generation of a file in a format that can be executed by said mobile depositing unit, said generation comprising the step of sectioning the set of all the structure portions arranged on the printing area with horizontal planes according to said prefixed vertical pitch, in order to generate a plurality of cross-sections of all the structure portions, each cross-section comprising solid areas and hollow areas, corresponding to the solid parts and to the hollow parts of all the structure portions in said cross-sections, sorting them from below towards the above.

In particular, said step of modelling provides modelling stiffening frameworks, in particular lower seal elements and/or upper seal elements for each structure portion, support bases and base seal elements for connecting structure portions to said support base.

Advantageously, said step of printing is made prearranging a depositing plane consisting of at least of one mobile carriage, said mobile carriage comprising a grid, a collection bottom container and a device for opening said depositing plane, so that during said step of printing said depositing plane is closed and said grid holds the granular bound and unbound material, whereas at the end of said step of printing said depositing plane is open for discharging in the bottom container through said grid the unbound granular material. In particular, a plurality is provided of carriages arranged adjacent to each other in order to form said depositing plane.

In particular, said mobile depositing unit is mounted on a frame, and said frame in turn is movable, such that at the end of a first step of printing executed in a first printing region of at least one structure portion, which has to complete a hardening phase and is immersed within unbound granular material, said frame is moved to a second printing region where another printing step can start, leaving said first printing region so that said structure portion can settle and complete hardening and then be cleaned removing said unbound granular material, obtaining said building structure.

Advantageously, said structure portions, at the end of said removal of the unbound granular material are subject to a step of soaking with said binding agent, in particular said step of soaking being made by spraying with and/or dipping in said binding agent, in particular said binding agent is a magnesium chloride, preferably magnesium chloride hexahydrate.

In particular, said step of printing provides the step for arranging in the printing area said lower seal elements by positioning them precisely compatible with the printing resolution of the machine.

In particular, said step of printing by the alternated deposit of granular material is carried out interrupting the process as said upper seal elements has to be laid at the last layer.

Preferably, at the end of said step of printing a step is provided of hardening each structure portion.

Advantageously, said assembling step in case the structure is of small size provides the steps of:

- stacking said structure portions onto each other;

- gluing said structure portions, in particular by a mortar of magnesium oxide and magnesium chloride or with other structural adhesive by adding mechanical reinforcing elements.

In particular, said assembling step in case of large structures provides at least one of the steps of:

- mounting a first structure portion to the respective base sealing element comprising said reference pins;

- arranging said reference pins in a respective groove;

- casting a sealing mortar for said longitudinal frameworks in the groove for all their length;

- positioning the upper seal element of the relative structure portion before said mortar settles allowing to longitudinal frameworks still partially free to enter the corresponding holes;

- positioning the structure portion neighbouring to said first structure portion arranging precisely said reference pins of the lower seal elements in the corresponding housings of the upper seal elements;

- putting said connection frameworks in the grooves, superimposing them to the longitudinal rods already present;

- casting the sealing mortar for the longitudinal frameworks in the grooves and for all their length.

Advantageously, said assembling step is repeated for all the structure portions obtaining different assembled parts. Advantageously, a step is provided of sealing the joints along the division planes of all the structure portions mutually connected by the lower seal elements with the corresponding upper seal elements always through a mortar of granular material and magnesium chloride hexahydrate.

A step can be provided of smoothing and polishing the assembled parts thus obtained.

Advantageously, said step of assembling is repeated for all the structure portions except from the assembling of adjacent structure portions to the adjacent portions that have to be mounted directly in situ so called 'keystones".

In particular, said step of assembling provides at least one of the steps of:

- prearranging the site obtaining a foundation terminating with a plane concrete slab;

- arranging the support base to the ground and preferably fixing it to the slab by fixing elements;

- mounting on the support base the parts and applying the missing structure portions called keystones by means of top cast of mortar that connects to each other the adjacent parts;

- continuing the step of assembling steps of the structure up to completion.

Advantageously, a step can be provided of sealing, smoothing and polishing the structure thus completed.

Said method of modelling and assembling provides one or more "special" structure portions that allow a structural matching for compensating possible errors of assembling structure portions during the assembling steps of the structure.

According to another aspect of the invention a method for quick production of a conglomerate building structure comprises the steps of:

- spraying a predetermined amount of a liquid component of said two-part binding agent by said mobile depositing unit on said first layer of granular material only at said solid areas of a first cross-section of said structure;

- pressing said second layer;

- removing the unbound granular material, obtaining said building structure,

wherein said binding agent is a inorganic two-component binding agent comprising:

- a liquid component containing inorganic substances, in particular chlorides or water or aqueous solutions;

- a powder solid component, based on metal oxides whose characteristic is that said powder solid component comprises at least one among magnesium oxide, silicon oxide, iron oxide, calcium oxide, aluminium oxide.

In particular, said inorganic liquid binding agent is magnesium chloride, preferably magnesium chloride hexahydrate, preferably at maximum concentration.

In particular, said granular material is selected from the group comprised of: dolomite or calcareous or siliceous sand, to which magnesium oxide is added, in particular in a ratio set between 15% and 30% by weight,

Advantageously, said powder solid component comprises fibres with a size less than 50 micrometres, in particular said fibres are in a ratio less than 2% of said powder solid component.

Preferably, said liquid component has a viscosity at room temperature set between 0.1 and 200 cP, preferably, between 1 and 20 cP.

According to a further aspect of the invention an apparatus for quick production of a conglomerate building structure comprises:

- a means for modelling in a computer-aided way a building structure model by a CAD software;

- a means for sectioning said building structure model with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross-sections of said building structure model, each cross- section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of said building structure in said cross- sections, said cross-sections sorted from below towards the above;

- a means for printing said building structure, said means for printing comprising:

- a support frame on which is material mobile depositing unit that is adapted to move on a predetermined printing zone, so that said mobile depositing unit can span horizontally said printing area and can move according to said prefixed vertical pitch,

- a means for depositing, associated with said mobile depositing unit, within said printing zone, a first uniform horizontal layer of granular material of thickness corresponding to said prefixed vertical pitch, wherein said granular material contains a powder solid component of a two-part binding agent; said means for depositing adapted to deposit a second uniform horizontal layer of granular material onto said first layer and further layers up to completion of a last layer of said building structure;

- a means for spraying, associated with said mobile depositing unit, a predetermined amount of a liquid component of said two-part binding agent on said first layer of granular material only at said solid areas of a first cross-section of said structure; said means for spraying adapted to spray a predetermined amount of binding agent also on said second layer only at said solid areas of a second cross-section consecutive to said first cross-section of said structure portion, as well as in a similar way on said further layers of said structure;

- a means to raise vertically said mobile depositing unit with respect to said support frame according to said prefixed vertical pitch at the end of the depositing step and of the spraying step of each layer by said means for depositing and by said means for spraying;

- pressing means for pressing each layer of deposited granular material by said means for depositing before that said means for spraying start said step of spraying;

- a means for removing unbound granular material, obtaining said building structure,

wherein said pressing means is adapted to provide a pressing intensity set between 0,01 and 1 Kg/cm², preferably between 0,05 and 0,5 kg/cm² on each layer of deposited granular material by said means for depositing.

Advantageously, said pressing means comprises at least one pressure roller, in particular a plurality of pressure rollers arranged adjacent to each other, a means being provided for moving transversally said plurality of pressure rollers at the end of a forth stroke, in order to carry out a back stroke in a position shifted transversally with respect to said forth stroke.

In particular, said apparatus comprises a frame defined by uprights and connected to each other by a boundary frame comprising beams within which the printing zone is defined, where the mobile depositing unit operates, characterised in that the uprights are mounted on wheels such that the support frame is displaced completely, and at the end of a first printing step, in a first printing region of at least one structure portion all the frame can be displaced to a second printing region where another printing step can start, leaving the first printing region free so that the structure portion made in the first printing region can settle and complete hardening and then be cleaned removing the granular unbound material.

Advantageously, said pressing means is mounted on a pressing carriage sliding independently from the mobile depositing unit and to this hookable by a connection mechanism, in particular a magnetic mechanism, such that when the mobile depositing unit has carried out a stroke of depositing the granular material the mobile depositing unit hooks the pressing carriage of the pressing rollers, and the pressing means is dragged by the mobile depositing unit in order to cause the rollers to carry out a step of compacting and "mixing" the layer of granular material.

In particular, each roller acts on the layer of granular material applying a pressure that is given by the ratio between the weight and the contact surface of the roller on the surface to work, the pressure being adjustable providing rollers with different form or size in order to increase/decrease the contact surface or providing rollers of higher weight.

Preferably, said rollers are associated to pushing means, in particular spring pushing means with a measured preloading force, which apply a force that is summed to the weight of the roller same.

Advantageously, said pressure rollers are mounted floating on said pressing carriage by means of arms in order to follow and always contact the surface of the layer of deposited granular material, in particular said rollers are raised/lowered by said arms.

In particular, a hopper is provided through which the layers of granular material are deposited, characterised in that said hopper comprises substantially an upper feeding section, integral to the perimetral frame, and a depositing section integral to said mobile depositing unit and having an open bottom, said feeding section and said depositing section being separate from each other by a plurality of feeding drawers, such that said feeding section feeds by gravity the depositing section, by said drawers, when they are aligned with each other.

In particular, a selective opening/closing mechanism is provided associated with a respective plate, which opens/closes a lower portion of the feeding section, in order to activate the fall of the granular material from the feeding section into the hopper and allowing to deposit layer strips of granular material of reduced width or only in some predetermined zones economizing on the amount of deposited granular material.

Advantageously, a suction device is provided of the granular material capable of causing the suction of the unbound granular material during the printing step and of bringing it back to the feeding section into the hopper. In particular, the suction device is movably mounted above the feeding section in order to distribute in an uniform way the granular material in the feeding section.

Brief description of the drawings

The invention will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

- Fig. 1 shows an example of structure having free shape modelled in a computer-aided way by a CAD software;

- Fig. 2 shows a diagrammatical view a simplified apparatus comprising a mobile depositing unit through which printing operations are made;

- Fig. 3 shows a perspective enlarged view of the mobile depositing unit of the apparatus of Fig. 2, having a plurality of nozzles mounted on a working head;

- Fig. 3A shows a diagrammatical detailed view of the nozzles of Fig. 3, which take the binding agent by a reservoir incorporated in the working head;

- Figs, from 4 to 7 show a succession of building steps of structure 100 by the simplified apparatus of Fig. 2;

- Fig. 8 shows a perspective view of the structure of Fig. 1 , sectioned by plane division surfaces of fixed thickness in order to define a plurality of structure portions;

- Fig. 9 shows a perspective view of the building steps of the structure portions suitably arranged on the printing area of the printer;

- Fig. 10 shows a perspective view of the apparatus of Fig. equipped by a depositing movable plane consisting of a plurality of carriages that have a bottom container for discharging the unbound material;

- Fig. 11 shows a perspective view of a mobile carriage of Fig. 10 adopted to form the depositing plane;

- Figs. 12 and 13 show a perspective view of the carriage of Fig. 16 having travel wheels and a removable grid for dipping the printed structure portions in a consolidating bath;

- Fig. 14 shows a perspective view of a generic portion of the structure of Fig. 8 emptied and sectioned into structure portions;

- Fig. 15 shows an enlarged view of a structure portion which highlights the presence of a connection edge and of grooves adapted to match the structure portions;

- Figs. 16 and 16A show respectively a lower seal element modelled directly on the lower surface of a structure generic portion and an enlarged view thereof;

- Figs. 18 and 18A show respectively an upper seal element modelled directly on the lower surface of a structure generic portion and an enlarged view thereof;

- Figs. 18 and 19 show a perspective view of a succession of assembling steps of the various structure portions that adopt reference pins mounted on special base seal elements;

- Figs. 19A and 19B show respectively a perspective view and an enlarged view of a connecting element which is resistant to cut used as alternative to the connection between structure portions of Fig. 18 and 19;

- Fig. 20 shows a diagrammatical view of a support base for the connection of structure portions of large size;

- Fig. 21 shows a perspective view of the assembling steps of the structure portions on the support base of Fig. 20;

- Figs, from 22 to 24 show a perspective view of successive assembling steps of the structure portions for making building structure 100, of Fig.

1 ;

- Fig. 25 shows a top plan view of an apparatus according to the invention in one detailed embodiment; - Fig. 25A shows an elevational side view from a first side of the apparatus of Fig. 25;

- Fig. 25B shows an elevational side view from an opposite side with respect to that of Fig. 25A of the apparatus of Fig. 25;

- Fig. 26 shows a perspective view of a printing carriage and of a pressing carriage that depicts the connection magnet which is adapted to couple them up with respect to each other;

- Fig. 27 shows a perspective view of the pressing rollers of the apparatus of Fig. 25;

- Fig. 28 shows a perspective view of the hopper containing the granular material and of mobile depositing unit 200 that is adapted to deposit and to print it;

- Fig. 28 shows an enlarged view of a vertical handling slide of the mobile depositing unit mounted at each upright;

- Fig. 28A shows an enlarged view of the working head of the mobile depositing unit of Fig. 28;

- Figs. 29 and 30 show a particular view respectively of the hopper for containing and depositing the granular material and of the travel wheels for moving the whole printing structure arranged at each upright;

- Fig. 31 shows a perspective view of a suction device associated with hopper 260 that is adapted to cause the suction of the unbound granular material in the printing area so that it can be reused.

Detailed description of some exemplary embodiments

With reference to Fig. 1 , a conglomerate structure 100 with any desired shape and size is made through a method, according to the invention, which provides the steps of computer modelling building structure 100 by a CAD software, in particular, with a function of surface modelling or of solid modelling, and sectioning the modelled building structure 100 with horizontal planes 1 , according to a prefixed vertical pitch, in order to generate a plurality of cross-sections 10' of building structure 100.

A next step of the method provides a step of printing building structure 100 in a printing area 70 on which a mobile depositing unit 200 acts that is adapted to deposit a construction material, according to a prefixed vertical pitch (Fig.1).

In particular, in Figs. 2, 3 and 3A mobile depositing unit 200, associated with apparatus 205, is shown in simplified version for better showing the printing process. In particular, apparatus 205 is without a boundary frame 60 and has only two uprights 201 that allow lifting a working head 210 having a reservoir of granular material 220 that is being laid. Fig. 3 shows, furthermore, working head 210 of the machine having a plurality of nozzles 211 , arranged as an array mounted on an auxiliary translating axis y, and which take the binding agent from a reservoir 211a (Fig. 3A) present in working head 210.

In particular, as shown in Figs, from 4 to 7, the printing step provides depositing, by working head 210, a first uniform horizontal layer 230 of granular material of thickness corresponding to the prefixed vertical pitch (Fig.4). In particular, the granular material contains a powder solid component of a two- part binding agent capable of binding with a liquid component deposited through nozzles 211 , which are arranged always on working head 210 (Fig. 5), adapted to spray a predetermined amount of liquid component 231 of the two-part binding agent on the first layer of the granular material only at the solid areas of the first cross-section of building structure 100.

Then, the mobile depositing unit is raised progressively of the prefixed vertical pitch and a second uniform horizontal layer 232 of granular material is deposited above first layer 230 (Fig.6). At that point, a step is done of pressing by a roller 300, or several adjacent rollers, directly on second layer 232 of granular material to assist the step of cross linking binding agent 231 and the compaction of first layer 230 with second layer 232 at the area where binding agent 231 has been sprayed.

Then, the step is repeated of spraying a predetermined amount of binding agent on second layer 232 only at the solid areas of a second cross- section consecutive to the first cross-section of building structure 100, and the steps are repeated in turn of raising vertically working head 210, of depositing granular material and of pressing up to completion of a last layer of building structure 100. Finally, (Fig.7) a step is provided of removal of the unbound granular material, obtaining building structure 100.

In detail, the step of pressing is adapted to obtain a pressing intensity set between 0,01 and 1 Kg/cm², preferably between 0,05 and 0,5 kg/cm². This way, the step of pressing with rollers 300 with a pressure intensity comprised within said range causes the pressing step not only to make level and regular the surface of deposited material, but provides a variable pressure energy, which is transmitted to the layer located underneath. In particular, the layer located underneath, not yet hardened, in the zones where the liquid component was spread, contains a mixture of granular material, of the solid component of the binding agent and of the liquid component of the binding agent. This pressure energy allows the mixture to be compressed and then released giving rise to an elementary "moulding step", supplying to the mixture a "reticulation energy" that assists the production of the crystal lattice of the two-part binding agent and of the conglomerate granular material. This way, the final solid composite material is very compact and homogeneous with subsequent good structural resistance.

More in detail, the inorganic two-component binding agent comprises a liquid component containing inorganic substances, in particular chlorides or water or aqueous solutions and a powder solid component, based on metal oxides. The liquid component has a viscosity at room temperature set between

0.1 and 200 cP, preferably between 1 and 20 cP.

In particular, the solid component powder comprises at least one among magnesium oxide, silicon oxide, iron oxide, calcium oxide, aluminium oxide, whereas the liquid component is magnesium chloride, preferably magnesium chloride hexahydrate, preferably at maximum concentration. More in particular, the granular material is selected from the group comprised of: dolomite or calcareous or siliceous sand, to which magnesium oxide is added, in particular in a ratio set between 15% and 30% by weight.

In addition, the powder solid component can comprise fibres with a size less than 50 micrometres, in particular said fibres are in a ratio less than 2% of said powder solid component.

This way, the powder solid component comprising fibres with the above described size and percentage and the liquid component, form a so-called Engineering Cement, which has high features of resistance but also of deformability to avoid fragile break.

In particular, according to the desired size of structure 100 and the size of printing area 70, the step of designing and modelling the structure can comprise the further steps of dividing building structure 100 by division surfaces 1 in order to define a plurality of structure portions 10, smaller, as shown in Fig. 8.

In particular, Fig. 8 shows an explicative example of structure 100 that may have a size comprised for example between 2 and 20 metres height, sectioned by division planes 1 , in particular horizontal section planes.

Structure portions 10 can be separated from each other by the planes or division surfaces 1. Alternatively, can be provided planes vertical or oblique, to obtain structure portions 10 of suitable size and in any case less than printing area 70. In particular, the sectioned surfaces can also provide vertical stairs- like divisions (not shown) of variable thickness for creating a discontinuity to obtain relatively simple portions 10. Structure 100 of Fig. 8 is cross-sectioned with section planes, without stairs, for simplicity, of fixed thickness s of about 50 cm. Normally, the sectioning criteria of structure 100 is that the thickness s of each portion 10 has to be proportioned to its maximum horizontal size avoiding too thin portions and preferring stubby portions 10.

Furthermore, a possible implementation of the method provides modelling at division surfaces 1 an assembling interface 2. In particular, assembling interface 2 is such that adjacent division surfaces 1 of adjacent structure portions 10 have a matching shape to each other (Fig.18 and 19). Alternatively, the assembling interface can provide connection elements 48 located in the recess of each structure portion (Fig. 19A).

Normally, assembling interface 2 can carry out the function of mechanical reference to the assembling steps and of stiffening framework, as described and shown below. The matching allows an operating structure 100 similar to that of structures of reinforced or prestressed concrete with post-tensioned technology.

In the same way, as above described, each structure portion 10 can be cross-sectioned with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross-sections of each structure portion. The cross-sections are sorted from below towards the above.

In particular, each cross-section comprises solid areas and blank areas, corresponding to the solid parts and to the hollow parts of the corresponding structure portion 10 in the cross-sections. The design step provides in fact emptying the inside of structure portions 10 in order to obtain a recess with a suitable thickness 10a of the walls, visible in Fig. 14, in order to define a side external wall 10' and a side internal wall 10".

Then, each structure portion or several structure portions are printed according to the steps described above.

In particular, as shown in Fig. 9, once defined the various structure portions 10 in the modelling step, there is a step of positioning them throughout printing area 70. In particular, they are positioned in order to maximize the area allotted to the solid portions with respect to the blank portions for a determined number of portions 10. In detail, the positioning step can be carried out according to a manual, semiautomatic or automatic procedure, which in the two-dimensional case is commonly called 'nesting', i.e. fitting each other. In detail, in the automatic procedure, when printing area 70 is full, all portions 10 distributed on the surface 70, are checked whether they are actually solid portions, and then the distribution is stored in a format that can be run by apparatus 205.

In particular, Fig. 9 shows a part of the portions or structure portions 10, suitably distributed on the area 70 with shape and size equal to that offered by the printer. For example the apparatus can have a printing area 70 of about 6x6 metres. This step is then repeated until all portions 10 of structure 100 have been extracted as well a certain number of print files has been obtained.

Then, the printing step of one or more generic structure portions 10 provides loading in the computer of apparatus 205 one of STL files (STereo- Litography) that have been previously created, and then the printing step is started from the first layer and then is prosecuted stepwise according to the printing vertical pitch, according to axis Z, for making structure portions 10.

This way, the amount of unbound material that is accumulated at the sides of structure portions 10 is low and allows excluding the need of containing walls that are not more necessary to the process, as provided in some devices of the prior art, without which the process cannot work.

Then, an implementation of the method provides a step of assembling steps of structure portions 10 thus made connecting to each other assembling interface 2 that perform the matching shape, in order to construct building structure 100 consisting step of modelling. The assembling step will described in detail then.

This possible embodiment of the process may avoid to make "in situ" the whole building, by moulding separately the various structure portions 10, providing them by successive printing sessions directly at the building yard and then assembling them. Furthermore, the process may not require making a shell or providing an appropriate container, as occurs in prior art, simplifying further the printing apparatus necessary to its construction, described below. A second advantage is that splitting, starting from the computer file the building structure into structure portions, the latter can be rearranged on the printing area 70 in an optimized way, increasing significantly the above cited ratio between solid areas and total area, multiplying the production rate of the machinery.

This method and the relative device allow making objects and structures with free shape of size higher than 0,1 metres, up even to a large size, for example about one meter or some metres, and without limits with respect to the final size, made of artificial rock.

Nevertheless, it is possible with the method according to the invention, to provide objects large as a single block up to even ten and beyond metres, made directly in situ, or in large blocks that can be moved for being mounted on destination.

In particular, as shown in Fig. 10, the printing step can be carried out prearranging one or more movable carriages 250 that form a depositing plane 250' comprising a grid 255 and a collection bottom container 252 having a plane with a plurality of apertures 251. In addition, a device is associated for opening the plane 250', so that during the printing step the plane is closed and the grid 255 supports the granular bound and unbound material, whereas at the end of the printing step the plane is open for discharging the granular material into the bottom container 252 through the apertures 251. This way, as shown in Fig. 12, structure portions 10 remain free above grid 255. Always in an advantageous way, depositing plane 250' can be detached from the bottom 252 to reach enough stiffness for allowing its lifting. This can be useful for example to allow dipping in a basin for impregnating structure portions 10.

In particular, when modelling by CAD the hollow structure portions 10, as previously described, a plurality of closed tracks arise corresponding to the lower surface of each structure portion 100 at the first plane cross-section of the structure. Advantageously, the tracks indicate to an operator the perimeter where to position lower seal elements 20.

The above described printing procedure by an alternated deposit of granular material and printing in the cross-section planes is carried out until upper seal elements 30 have to arranged on the last layer.

At the end of the printing procedure, as shown in Fig. 19A, the structure portions are stayed to settle for at least 24 hours and then the extraction of structure portions 10 is carried out.

The operation of extraction is carried out simply by operating discharge grids 253 of movable bottom container 252 thus allowing to the unbound granular material to free structure portions 10, as shown in Figs. 19A and 19B.

Fig. 19B shows instead a carriage 251 spaced apart from the other for carrying the articles 10 to a next treatment.

Fig. 19C shows finally an upper grid 255 of carriage 251 raised from its support to allow dipping structure portions 10 into a soaking basin for consolidating the resistance. In particular, impregnating structure portions 10 by spraying can be carried out in a basin (not shown) where a variety of types of soaking liquids available on the market can be provided, among which preferably a salt solution of magnesium chloride hexahydrate can be used, that is already available for the printing process. This way, the dipping of structure portions 10 in the soaking bath allows the completion of the reaction of all the oxides that may not have reacted, obtaining a structure portion 10 of good resistance and impermeability.

The above described operations of printing and hardening are repeated for all the STL files necessary to construct structure 100.

In particular, the CAD modelling steps are described below of structures of large size where the problems of weight, of resistance and of assembling are highly important.

In a first exemplary embodiment, for assembling to each other the various structure portions 10, as shown in Figs. 10 and 11 , each structure portion can provide a plurality of longitudinal grooves or ribs 10b approximately parallel and continuous between adjacent portions, that are made in thickness 10a of the wall at the edge of inner side face 10". In particular, a step of emptying structure 100 to generate each portion 10 that can be equipped with the inner ribs 10b can be carried out also before the step of cross-sectioning it by the CAD software. Grooves 10b can be provided to house longitudinal stiffening frameworks, as described and shown below. If structure 100 is of small size and made of a single part or of a few structure portions 10 the grooves 10b may not be provided.

In particular, Fig. 14 shows a generic part 110 of structure portion 100 that is hollow and cross-sectioned and a succession of adjacent portions 11 , 12, 13, and 14 stacked on each other.

In particular on each portion 11 , 12, 13, and 14 is provided the embodiment of one or more boundary recesses of thickness and depth that is adapted to define an edge boundary 10c (Fig.15) used as reference in the assembling the portions. In particular, the edge boundary 10c is obtained on a lower surface 10d of each portion 11 ,12,13 and 14.

Optional operations can be carried out in case structure portions 10 have to bear significant stresses or involve assembling problems. Such operations provide modelling also the stiffening frameworks such as lower seal elements 20 and upper seal elements 30 for each structure portion 10, base seal elements 40 and one or more support bases 50.

In the first case, as shown in Fig. 16, lower seal elements 20 are modelled on the lower surface 10d of each structure portion 10, at the excavation boundary 10a (visible in Fig. 16A). In detail, the seal 20 is a seal of interface flat and closed that covers the outer perimeter of the relative structure portion 10. Preferably, lower seal element 20 has fixed width and is internally tangential to the longitudinal frameworks present in that section. Furthermore, seal element 20 can comprise holes 20' adapted to house reference pins for correct mechanical matching of structure portion 10 with neighbouring portions. In particular, lower seal element 20 may for example have a thickness of 5 mm and a width 15 mm and can be made by a numerical control cutting machine tool of the laser or water jet type capable of keeping a plane form during manipulation.

Advantageously, during the printing step of structure portions 10 a plurality of closed tracks is made corresponding to the first cross-section plane of the lower surface of each structure portion 10. The tracks indicate to an operator the perimeter in which the possible lower seal elements 20 can be positioned.

This way, lower seal elements 20 so arranged in the printing area provide structure portions 10 that are equipped below with embedded lower seal elements 20.

In a same way, as shown in Figs. 17 and 17A, on upper surface 10e of each structure portion 10 a flat and closed upper seal element 30 that follows the outer perimeter of structure portion 10 is provided. In this case, preferably, the modelling is carried out on a path shifted towards the inside side face 10" of each portion 10 (offset). In particular, the width of upper seal element 30 can go beyond the diameter of longitudinal frameworks 41. In particular, in the vicinity of the axis of each longitudinal framework element that is put in the grooves 10b, furthermore, holes 30' (Fig. 17A) are made of size not much larger of the diameter of the frameworks. For example, the upper seal element has a thickness 5 mm and width 80 mm, made by means of numerical control cutting machine tool of the laser or water jet type.

The above described modelling steps, furthermore, are followed for making a base sealing element 40, visible in Fig. 18, that is adapted to connect a first structure portion 10 with a support base 50, visible in Fig. 20. In particular, from base sealing element 40 longitudinal framework elements 41 extend, in particular pins or anchoring members, having a length less than double of the sum of the thicknesses of two adjacent structure portions 10/10' (Fig.18) in which they will be housed. In particular, the pins or anchoring members 41 are adapted to absorb the tensile stresses coming from structure 100 and then transferred to base frame 50 and from here to the ground. Furthermore, Fig. 18 depicts the presence of reference holes 42 for mechanical connection with base 50.

In case, instead, of large structures, it is provided that, as shown in Fig.

19, arranging structure portion 10 on respective base sealing element 40 .comprising anchoring members 41 , and housing each element in a respective groove 10b that is made in corresponding structure portion 10.

Then a step is provided of casting a sealing mortar 90 into longitudinal frameworks 41 within grooves 10b and for all their length.

In parallel to each other, it is necessary positioning upper seal element 30 before the mortar settles allowing longitudinal frameworks 41 , still partially free, to enter the respective holes 30'. In an advantageous way, upper seal element 30 guides vertical pins 41 forcing them in a desired direction. Then, always as shown in Fig. 19, a neighbouring structure portion 10 is arranged causing reference pins of the lower seal element, not shown, to fit in the corresponding housings of upper seal elements 30 of the structure portion located underneath. This way, the faces of structure portions 10 that enter into contact with each other are the smooth faces of lower seal element 20 and upper seal element 30 in order to obtain a precise mechanical matching. The part thus obtained has a high resistance against bending and, since it is hollow, a very low weight is obtained with large advantages in the behaviour of structure 100 in zones subject to earthquakes.

A second exemplary embodiment for assembling to each other the various structure portions 10 comprises, alternatively to the mounting method with reference pins 41 , the use of a connecting element 48 (Fig.19A and 19B) which is resistant to shear stress and is put in recess 10g of structure portions 10 and blocked there by filling the recess for example with concrete mortar. In particular, the connecting element 48 comprises a first and a second plate 48a inserted in each other in order to form substantially a connecting element cross-like. In detail, first plate 48a comprises a central opening 48d within which second plate 48b fits and protrudes symmetrically at opposite sides from first plate 48a. The latter comprises, furthermore, a protruding tongue 48c, having a hooking hole 48f, that is adapted to protrude outside from internal/external surface of the respective structure portion 10 in order to work as hooking point for a pulling element.

In addition, plate 48a comprises, as shown always in Fig. 19B, two apertures or holes 48e such that mounting longitudinal cables, not shown, can pass. This way, prearranging several connection elements 48 distant from each other at the connection lines between two adjacent structure portions 10 inner building structure 100 is assembled. This solution is very easy and quick as well as cheap.

Fig. 20 shows support base 50 also CAD modelled for correctly mounting all structure 100, comprising references 40' adapted to assemble base seal elements 40 or counter-bases that hold the structure portions 10 that make up structure 100.

Fig. 21 shows structure portions 10 having base seal elements 40 mounted on support base 50. In particular, a production step of the above described lower seal elements 20, upper seal elements 30, base seal elements 40 and support base 50 in addition to longitudinal frameworks, is made by prearranging lower seal elements 20, upper seal elements 30, support base 50 and base seal elements 40 made by numerical control cutting machine tools in 1 :1 scale starting from the CAD models.

Then, in the step of modelling a step of prearranging reference elements or pins (not shown) in lower seal elements 20 or in upper seal elements 30 can be provided, before or after the building steps of structure portions 10. In particular, in case they are applied to lower seal elements 20, before printing, they should have a limited length, determined by the lower plane of seal 20 according to the printing pitch and not come out below for a height within the thickness of the seal element. For example, if the printing pitch is 10 mm and the thickness of seal elements 20 is 5 mm, such pins would have a total length within 15 mm. Advantageously, such pins are set to allow the precise assembling of structure portions 10 and to act as interface between adjacent portions 10 obtaining matching shape 2.

The final operations consist in assembling the various structure portions 10 in order to build modelled structure 100 (Figs. 22 and 23). In particular, the step of assembling, in case structure 100 is of small size, consists in stacking structure portions 10 on one another preferably gluing the parts with a mortar of magnesium oxide and magnesium chloride, or with other adhesive, even by adding mechanical reinforcing elements.

In case, instead, of large structures, as shown in Fig. 20, structure portion 10 is arranged on respective base sealing element 40 comprising anchoring members 41 and housing each element in a respective groove 10b made in corresponding structure portion 10. The above described operations are then repeated for all structure portions 10 obtaining different assembled parts 110. In an advantageous way, a step is provided of sealing the joints along division planes 1 of all portions 10 mutually connected by lower seal elements 20 with the corresponding upper seal elements 30, by adding a mortar of granular material and magnesium chloride hexahydrate. Finally, a step can be provided of smoothing and polishing assembled parts 110 thus obtained. Such operations of assembling are repeated for all structure portions 10 except from the assembling the adjacent structure portions to the adjacent portions that have to be mounted directly in situ that are the connecting portions 120 (Fig. 22).

The assembling steps of structure 100 at the chosen site, as shown in

Figs. 22, 23 and 24, provides then prearranging the site obtaining a foundation with a plane concrete slab and arranging support base 50 on it and preferably fixing it to the slab by fixing elements. Then, the steps of assembling comprises mounting to support base 50 the parts 110, as shown in Fig. 21 , and applying the other structure portions. Structure portions 120 are connected to parts 110 by means of a top cast of mortar that connects to each other the adjacent parts 110. These operations are repeated up to the completion of structure 100. Fig. 24 shows two parts 110 connected to each other by a structure portion 120 defined 'keystone that ensures the soundness of the structure and of the two parts 110. Even in this case a step can be provided of sealing, smoothing and polishing structure 100 thus completed.

Said method of modelling and assembling allows, furthermore, to provide one or more "special" structure portions that allow a structural matching for compensating possible errors of assembling structure portions 10 during the assembling steps of structure 100.

Figs, from 25 to 31 show in detail an apparatus 500, according to a preferred exemplary embodiment, that is adapted to work according to the method described above.

In particular, apparatus 500 comprises a electronic hardware means comprised in a control panel 400 for loading a CAD building structure file using an CAD program and dedicated program means capable of sectioning the building structure with horizontal planes according to the prefixed vertical pitch, in order to generate a plurality of cross-sections. Each cross-section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of building structure 100.

Control panel 400, as better shown in Figs. 25A and 25B, is arranged in an elevated position such that an operator can control the various printing steps described above and preferably intervene if unexpected situations occur. To control panel 400 automatic control systems can be associated capable of monitoring each building step of the structure and of comparing it with the reference CAD image.

From a structural viewpoint, as shown in Fig. 25 and following Figs. , apparatus 500 comprises a frame 60 defined by four uprights 61 arranged substantially at the vertices of a rectangle and connected to each other by a boundary frame comprising reticular girders 60a within which printing area 70 is defined, where mobile depositing unit operates 200, according to the method described above with reference to Figs, from 4 to 7. In particular, mobile depositing unit 200 is mounted on a support slide 215 (Fig.26) sliding on a guide 63 integral to boundary frame 60a. Guide 63 is arranged substantially in position of a middle line of printing area 70 defined by boundary frame 60a, as shown in Fig. 25. This way, mobile depositing unit 200 is capable of covering horizontally all printing area 70. More in detail, slide 251 is associated with a motor 65 on which a gear is mounted 64a that is adapted to slide on a rack 64 integral to guide 63. (Fig.27). This way, through printing carriage 215 mobile depositing unit 200 is capable of translating with alternated movement according to a first direction identified with the axis X. In addition, printing carriage 215, and then mobile depositing unit 200, is capable of translating according to an axis y, orthogonal to axis x, and arranged on a same plane by two guides 235, parallel to each other, which form a sliding coupling with corresponding sliding portions 236, shown partially, mounted integral to printing carriage 215.

In addition, as above described, mobile depositing unit 200 moves vertically according to axis z, carrying vertically boundary frame 60a and guide 63 by means of respective vertical slides 62, mounted at each respective upright 61. In particular, slides 62 are arranged at the vertices of boundary frame 60a and are the sliding elements along uprights 61. More precisely, each vertical slide 62 provides a motor 62a capable of translating vertically along a screw 61a that extends for all the length of upright 61 (Fig.28 and 28A). This way, mobile depositing unit 200 and boundary frame 60a move integrally along uprights 61. Finally, as better shown in Fig. 29 and in the enlarged view of Fig. 30, uprights 61 are mounted on wheels 80 such that the support frame 60 is displaced completely. This way, at the end of a first printing step, in a first printing region of at least one structure portion, the structure portion has to complete a hardening phase and is surrounded by granular unbound material. At that point, all frame 60 is moved to a second printing region where another printing step can start, leaving the first printing region so that the structure portion can settle and complete hardening and then be cleaned removing the granular unbound material.

As above described, mobile depositing unit 200 comprises a working head 210 that provides a plurality of nozzles 211 for spraying the liquid component of the two-part binding agent, capable of spraying the binding agent in a programmed way. Nozzles 211 (Fig.28B) are open only at the zone corresponding to the solid parts of the cross-section and simply fed by a reservoir of liquid binding agent 225 (Fig.28B).

Furthermore, Fig. 26, shows partially pressing rollers 300 mounted on a girder 302 (Fig.25) in turn sliding with respect to guide 63 by a pressing carriage 315. In this case, pressing carriage 315 is moved through by printing carriage 215 by a connection mechanism, in particular a magnetic mechanism. More in particular, the connection mechanism has a magnet 216 integral to printing carriage 215 and a ferromagnetic body 316 integral to pressing carriage 315. It is obtained then that, when mobile depositing unit 200 effects a stroke of depositing the granular material, printing carriage 215 reaches pressing carriage 315 of pressure rollers 300, operating the magnet 216 that produces an attraction force on ferromagnetic body 216. This way, girder 302 and pressure rollers 300 are dragged by printing carriage 215 in order to cause the rollers to effect a step of compacting and "mixing" the layer of granular material. This action, as above described, can produce a pressing intensity set between 0,01 and 1 Kg/cm² in order to provide a pressing energy, which is transmitted to the layer located underneath and allows the mixture of granular material and of two-part binding agent to mix in order to obtain the production of the crystal lattice.

In particular, each roller acts on the layer of granular material applying a pressure that is given by the ratio between the weight and the contact surface of the roller on the surface to work. For adjusting this pressure rollers can be provided with different form or size in order to increase/decrease the contact surface or providing rollers of higher weight. Alternatively, or in addition, a means can be provided, for example a spring means with a measured preloaded force, that applies such force that is summed to the weight of the roller same. This way, it is possible to adapt to the chosen granular material and to the type of binding agent, adjusting the intensity of the pressure of rollers 300 on the granular layer, in a way to obtain a mixing effect that assists the cross linking in the material.

In the same way of printing carriage 215, pressing carriage 315 can move in a transversal direction by transversal sliding guides 335 that form a sliding coupling with respective sliding portions 336. This allows moving along all the distance existing between pressure rollers 300, causing the rollers to follow a forth stroke and a back stroke transversally shifted to each other. In detail, pressure rollers 300 are mounted floating on girders 302 by means of arms 330 (Fig.27) in order to follow and always contact the surface of the layer of deposited granular material. This solution assists furthermore their translation in a transversal direction since it allows lifting them so that they do not create a friction with the layer of granular material.

In addition, associated with mobile depositing unit 200 a hopper 260 (Fig.29) can be provided through which the layers of granular material are deposited, with a thickness corresponding to the vertical pitch according to axis z. In particular, hopper 260 is a reticular structure member that forms a container within which the granular material is deposited. In particular, hopper 260 comprises substantially an upper feeding section 265, integral to boundary frame 6Oa₁ and a depositing section 220, separated from each other by a plurality of feeding drawers 264. In particular, feeding section 265 feeds by gravity depositing section 220, by drawers 264, when they are located aligned with each other (Fig.28). This occurs preferably each time that a layer of granular material is deposited. In particular, depositing section 220 has an open upper end through which the granular material comes and a bottom open end 220a (Fig.29). More precisely, the bottom open end of depositing section 220 is coincides with the layer of granular material that is being deposited in the first depositing step or in the successive depositing steps. To assist and lead the fall of the granular material from feeding section 265 to depositing section 220 rubber deflectors are provided that extend starting from the bottom of feeding section 265 up to the upper end of depositing section 220. This way, leaks of granular material are avoided. In particular, drawers 264 can comprise a mechanism for a selective opening/closing 264a connected substantially to a respective plate, not shown, which opens/closes a lower portion of feeding section 265. This way, the series of plates placed adjacent to each other opens/closes completely or partially feeding section 265. This allows activating a fall of the granular material from feeding section 265 of hopper 260 to a predetermined zone. This way, it is possible to deposit layers of granular material of reduced width or only in some predetermined zones economizing on the amount of deposited granular material.

As shown in Fig. 31 , a suction device 350 of the granular material can be associated to hopper 260 and is capable of causing the suction of the unbound granular material during the printing step and of bringing it back to feeding section 265 of hopper 260. In particular, suction device 350 is movably mounted above feeding section 265 in such a way that it is suitable for distributing in an uniform way the granular material in feeding section 265. More in detail, suction device 350 is arranged integral to a movable plate 351 that has an opening 352 that faces feeding section 265 (Fig.31). Movable plate 351 is operated by a motor 354 and by a flexible mechanical transmission 355 for actuating the suction device providing an alternated movement according to the axis y. To an inlet port 356 of suction device 350, a suction tube is mounted, not shown, to allow the suction of the granular material present in printing area 70.

The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

1. A method for quick production of a conglomerate building structure comprising the steps of:

- sectioning said building structure model with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross-sections of said building structure model, each cross-section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of said building structure in said cross- sections, said cross-sections sorted from below towards the above;

^■ prearranging a printing area and a material mobile depositing unit, so that said mobile depositing unit can span horizontally said printing area and can move according to said prefixed vertical pitch,

^■ depositing, by said mobile depositing unit within said printing area, a first uniform horizontal layer of granular material of thickness corresponding to said prefixed vertical pitch, wherein said granular material contains a powder solid component of a two-part binding agent;

^■ spraying a predetermined amount of a liquid component of said two-part binding agent by said mobile depositing unit on said first layer of granular material only at said solid areas of a first cross- section of said structure;

^■ raising vertically said mobile depositing unit with respect to said fixed frame according to said prefixed vertical pitch;

^■ depositing a second uniform horizontal layer of granular material onto said first layer;

^■ pressing said second layer;

^■ spraying a predetermined amount of binding agent on said second layer only at said solid areas of a second cross-section consecutive to said first cross-section of said structure;

■ repeating for further layers the step of depositing granular material, of spraying a predetermined amount of binding agent, of raising vertically said mobile depositing unit and of pressing up to completion of a last layer of said building structure;

■ removing the unbound granular material, obtaining said building structure,

characterised in that said step of pressing occurs by a pressing intensity set between 0,01 and 1 Kg/cm², preferably between 0,05 and

0,5 kg/cm².

2. A method, according to claim 1 , wherein they the following further steps are provided:

■ modelling structure portions, said step of modelling comprising the further steps of:

■ splitting into portions said building structure model by means of division surfaces in order to define a plurality of said structure portions, said structure portions being separated from each other by said division surfaces;

■ providing for each structure portion, at said division surfaces, an assembling interface, such that adjacent division surfaces of adjacent structure portions make up a shape matching with each other;

^■ sectioning each structure portion with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross- sections of each structure portion, each cross-section comprising solid areas and hollow areas, corresponding to the solid parts and to the hollow parts of said structure portion in said cross-section, said cross-sections sorted from below towards the above;

■ printing said structure portions;

^■ assembling said plurality of structure portions by connecting to each other said assembling interfaces that provide said matching shape, in order to construct said building structure corresponding to said building structure model.

3. Method according to claim 1 , wherein said step of modelling provides also a step of creating a recess in each structure portion in order to obtain hollow structure portions defined by walls with a determined thickness.

4. Method according to claim 2, wherein said step of modelling provides the step of creating in said walls a plurality of longitudinal grooves substantially parallel to each other made in said thickness, said longitudinal grooves being substantially continuous with neighbouring structure portions, said grooves adapted to house inserts in order to provide said assembling interface with matching shape, in particular said inserts selected from the group comprised of: reinforcement iron bars, seal elements, connection flange and/or connection pins.

5. Method according to claim 1 , wherein said step of modelling provides a step of creation on a lower surface of each structure portion of one or more boundary recesses of thickness and depth that is adapted to determine an boundary connection edge, which forms a matching reference shape between neighbouring structure portions.

6. Method according to claim 1 , wherein said printing step of said structure portions provides a preliminary step of distributing said structure portions in the printing area in order to exploit as far as possible the printing zone, in order to obtain a maximum area of the solid portions with respect to blank portions, said step of distributing comprising the generation of a file in a format that can be executed by said mobile depositing unit, said generation comprising the step of sectioning the set of all the structure portions arranged on the printing area with horizontal planes according to said prefixed vertical pitch, in order to generate a plurality of cross- sections of all the structure portions, each cross-section comprising solid areas and hollow areas, corresponding to the solid parts and to the hollow parts of all the structure portions in said cross-sections, sorting them from below towards the above.

7. Method according to claim 1 , wherein said step of modelling provides modelling stiffening frameworks, in particular lower seal elements and/or upper seal elements for each structure portion, support bases and base seal elements for connecting structure portions to said support base.

8. Method according to claim 1, wherein said printing step is made prearranging a depositing plane consisting of at least of one mobile carriage, said mobile carriage comprising a grid, a collection bottom container and a device for opening said depositing plane, so that during said printing step said depositing plane is closed and said grid holds the granular bound and unbound material, whereas at the end of said printing step said depositing plane is open for discharging in the bottom container through said grid the unbound granular material.

9. Method according to claim 1 , wherein said mobile depositing unit is mounted on a frame, and said frame in turn is movable, such that at the end of a first printing step that is executed in a first printing region of at least one structure portion, which has to complete a hardening phase and is immersed within unbound granular material, said frame is moved to a second printing region where another printing step can start, leaving said first printing region so that said structure portion can settle and complete hardening and then be cleaned removing said unbound granular material, obtaining said building structure.

10. Method a method for quick production of a conglomerate building structure comprising the steps of:

- sectioning said building structure model with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross-sections of said building structure model, each cross- section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of said building structure in said cross-sections, said cross-sections sorted from below towards the above;

- printing said building structure, said printing step comprising the further steps of: ^■ prearranging a printing area and a material mobile depositing unit, so that said mobile depositing unit can span horizontally said printing area and can move according to said prefixed vertical pitch,

■ depositing, by said mobile depositing unit within said printing area, a first uniform horizontal layer of granular material of thickness corresponding to said prefixed vertical pitch, wherein said granular material contains a powder solid component of a two-part binding agent;

■ spraying a predetermined amount of a liquid component of said two-part binding agent by said mobile depositing unit on said first layer of granular material only at said solid areas of a first cross- section of said structure;

^■ pressing said second layer;

^■ repeating for further layers the step of depositing granular material, of spraying a predetermined amount of binding agent, of raising vertically said mobile depositing unit and of pressing up to completion of a last layer of said building structure;

^■ removing the unbound granular material, obtaining said building structure,

- a powder solid component, based on metal oxides

whose characteristic is that said powder solid component comprises at least one among magnesium oxide, silicon oxide, iron oxide, calcium oxide, aluminium oxide,

in particular, said inorganic liquid binding agent is magnesium chloride, preferably magnesium chloride hexahydrate, preferably at maximum concentration,

in particular, said granular material is selected from the group comprised of: dolomite or calcareous or siliceous sand, to which magnesium oxide is added, in particular in a ratio set between 15% and 30% by weight.

11. A method according to claim 11 , wherein said powder solid component comprises fibres with a size less than 50 micrometres, in particular said fibres are in a ratio less than 2% of said powder solid component.

12. A method according to claim 11 , wherein said liquid component has a viscosity at room temperature set between 0.1 and 200 cP, preferably, between 1 and 20 cP.

13. An apparatus for quick production of a conglomerate building structure comprising:

- a means for sectioning said building structure model with horizontal planes according to a prefixed vertical pitch, in order to generate a plurality of cross-sections of said building structure model, each cross-section comprising solid areas and blank areas corresponding to the solid parts and to the hollow parts of said building structure in said cross-sections, said cross-sections sorted from below towards the above;

^■ a support frame on which is material mobile depositing unit that is adapted to move on a predetermined printing zone, so that said mobile depositing unit can span horizontally said printing area and can move according to said prefixed vertical pitch,

^■ a means for depositing, associated with said mobile depositing unit, within said printing zone, a first uniform horizontal layer of granular material of thickness corresponding to said prefixed vertical pitch, wherein said granular material contains a powder solid component of a two-part binding agent; said means for depositing adapted to deposit a second uniform horizontal layer of granular material onto said first layer and further layers up to completion of a last layer of said building structure

^■ a means for spraying, associated with said mobile depositing unit, a predetermined amount of a liquid component of said two-part binding agent on said first layer of granular material only at said solid areas of a first cross-section of said structure; said means for spraying adapted to spray a predetermined amount of binding agent also on said second layer only at said solid areas of a second cross-section consecutive to said first cross-section of said structure portion, as well as in a similar way on said further layers of said structure;

^■ a means to raise vertically said mobile depositing unit with respect to said support frame according to said prefixed vertical pitch at the end of the depositing step and of the spraying step of each layer by said means for depositing and by said means for spraying;

^■ pressing means for pressing each layer of deposited granular material by said means for depositing before that said means for spraying start said step of spraying;

» a means for removing unbound granular material, obtaining said building structure,

characterised in that said pressing means is adapted to provide a pressing intensity set between 0,01 and 1 Kg/cm², preferably between 0,05 and 0,5 kg/cm² on each layer of deposited granular material by said means for depositing.

14. An apparatus for quick production of a building structure, according to claim 13, wherein said pressing means comprises at least one pressure

^■ roller, in particular a plurality of pressure rollers arranged adjacent to each other, a means being provided for moving transversally said plurality of pressure rollers at the end of a forth stroke, in order to carry out a back stroke in a position shifted transversally with respect to said forth stroke.

15. An apparatus for quick production of a building structure, according to claim 13, wherein said apparatus comprises a frame defined by uprights and connected to each other by a boundary frame comprising beams within which the printing zone is defined, where the mobile depositing unit operates,

characterised in that the uprights are mounted on wheels such that the support frame is displaced completely, and at the end of a first printing step, in a first printing region of at least one structure portion all the frame can be displaced to a second printing region where another printing step can start, leaving the first printing region free so that the structure portion made in the first printing region can settle and complete hardening and then be cleaned removing the granular unbound material.

16. An apparatus for quick production of a building structure, according to claim 13, wherein said pressing means is mounted on a pressing carriage sliding independently from the mobile depositing unit and to this hookable by a connection mechanism, in particular a magnetic mechanism, such that when the mobile depositing unit has carried out a stroke of depositing the granular material the mobile depositing unit hooks the pressing carriage of the pressing rollers, and the pressing means is dragged by the mobile depositing unit in order to cause the rollers to carry out a step of compacting and "mixing" the layer of granular material.

17. An apparatus for quick production of a building structure, according to claim 16, wherein each roller acts on the layer of granular material applying a pressure that is given by the ratio between the weight and the contact surface of the roller on the surface to work, the pressure being adjustable providing rollers with different form or size in order to increase/decrease the contact surface or providing rollers of higher weight.

18. An apparatus for quick production of a building structure, according to claim 16, wherein to said rollers are associated to pushing means, in particular spring pushing means with a measured preloading force, which apply a force that is summed to the weight of the roller same.

19. An apparatus for quick production of a building structure, according to claim 16, wherein said pressure rollers are mounted floating on said pressing carriage by means of arms in order to follow and always contact the surface of the layer of deposited granular material, in particular said rollers are raised/lowered by said arms.

20. An apparatus for quick production of a building structure, according to claim 13, wherein a hopper is provided through which the layers of granular material are deposited, characterised in that said hopper comprises substantially an upper feeding section, integral to the perimetral frame, and a depositing section integral to said mobile depositing unit and having an open bottom, said feeding section and said depositing section being separate from each other by a plurality of feeding drawers, such that said feeding section feeds by gravity the depositing section, by said drawers, when these are located aligned with each other.

21. An apparatus for quick production of a building structure, according to claim 20, wherein a selective opening/closing mechanism is provided associated with a respective plate, which opens/closes a lower portion of the feeding section, in order to activate the fall of the granular material from the feeding section into the hopper and allowing to deposit layer strips of granular material of reduced width or only in some predetermined zones, economizing on the amount of deposited granular material.

22. An apparatus for quick production of a building structure, according to claim 20, wherein a suction device is provided of the granular material capable of causing the suction of the unbound granular material during the printing step and of bringing it back to the feeding section into the hopper, in particular, the suction device is movably mounted above the feeding section in order to distribute in an uniform way the granular material in the feeding section.