WO2023089454A1

WO2023089454A1 - Method for manufacturing three-dimensional articles by additive manufacturing and three-dimensional article so obtained

Info

Publication number: WO2023089454A1
Application number: PCT/IB2022/060780
Authority: WO
Inventors: Luca Toncelli; Gabriele Corletto
Original assignee: Breton S.P.A.
Priority date: 2021-11-16
Filing date: 2022-11-09
Publication date: 2023-05-25

Abstract

Method for manufacturing three-dimensional articles (1) by additive manufacturing, comprising a step i) of arranging on a support plane (P) a support element (4) comprising a plurality of surfaces (6A, 6B, 6 C) and a step ii) of depositing one or more layers of a material for additive manufacturing on at least one of the surfaces (6A, 6B, 6 C) of the support element (4) for forming at least one shaped member (8) which forms, alone or in part, the three-dimensional article (1). The support element (4) is made of a material which is different from the material for additive manufacturing. The invention also relates to a three- dimensional article (1) comprising a core portion (12) with a plurality of surfaces (6A, 6B, 6C) and at least one shaped portion (8) obtained by means of deposition of layers of a material for additive manufacturing on at least one of the surfaces (6A, 6B, 6 C) of the core portion (12). The material of the core portion (12) is different from the material for additive manufacturing and the core portion (12) has a cellular structure.

Description

“Method for manufacturing three-dimensional articles by additive manufacturing and three- dimensional article so obtained”

The present invention relates to the technical field of the production of three-dimensional articles by means of additive manufacturing, namely 3D printing.

In particular, the present invention relates to a method for manufacturing three-dimensional articles which involves a step of depositing one or more superimposed or adjoining layers of a material for additive manufacturing.

In the continuation of the present description the expression “superimposed or adjoining layers” is understood as meaning layers of material which are superimposed partly or totally or are arranged alongside each other with respective surfaces at least partially making contact.

For some time, methods for manufacturing three-dimensional articles which involve the deposition of one or more layers of material for additive manufacturing, for example thermoplastic material, have been known.

Generally the thermoplastic material used for additive manufacturing is chosen from the group comprising acrylonitrile butadiene styrene (ABS), as such or reinforced with structural fibres, nylon, as such or reinforced with structural fibres, polycarbonates which may be reinforced with structural fibres, polyether ether ketone (PEEK), polypropylene (PP) and polylactic acid (PLA).

In a manner known per se, thermoplastic material is suitable for being heated, melted, extruded and deposited in superimposed or adjoining layers on a substantially horizonal support plane, using a technology better known as fused deposition modelling.

Alternatively, the material for additive manufacturing may also be chosen from the group which comprises composite materials, metallic materials and ceramic materials.

The deposition of layers of material is performed by means of an extrusion device of a numerical control machine for additive manufacturing, also called a 3D printing machine.

Generally, the extrusion device is movable above the support plane by means of movement means of the Cartesian or anthropomorphic type.

In particular, the extrusion device may be movable along two horizontal axes which are perpendicular to each other and along a third vertical axis; furthermore, the extrusion device may be movable around two further axes of rotation.

The three-dimensional articles which can be obtained using the known methods have complex configurations comprising, for example, at least one complex curved surface, as shown more clearly in Figures 1 and 2.

In the context of the present description, a curved surface with a complex configuration may be defined as such if it has, for example, radii of curvature which are different at different points. Furthermore, the material for additive manufacturing, immediately after deposition, is semifluid or paste-like and usually does not have physical and mechanical properties which allow it to be self-supporting, in particular on curved surfaces, especially if complex.

In this connection, usually it is required to provide or arrange one or more support elements on the surface supporting the machine before depositing the layers of materials, the support elements being designed to support the layers of material deposited and prevent the collapse or yielding thereof, in particular at the complex curved surfaces.

Generally, also the support elements are made by means of deposition of superimposed or adjoining layers of a material for additive manufacturing.

In particular, the formation of the three-dimensional element with the respective support element takes place during a sole deposition process which uses a single extrusion device and a single material for additive manufacturing.

With reference to Figure 1, the support element 101 of the type indicated above and commonly used in the processes for manufacturing three-dimensional articles comprises a plurality of vertical uprights 103, i.e. uprights which are perpendicular to the support plane P when the support element 101 is positioned on the same surface P.

In this embodiment:

- the top end of the uprights 103 forms a support base or surface for the layers of material deposited by means of the extrusion device D which will form the three-dimensional article 105;

- the first layers of material deposited on the support plane P form the support element 101 and the layers of materials which are subsequently deposited and superimposed on the first layers form the remaining part of the support element 101 and the three-dimensional article 105 having at least one complex curved surface.

Subsequently, the support element 101 is separated from the three-dimensional article 105. Preferably, the support element 101 and the three-dimensional article 105 may be formed, by means of deposition of the layers on the support plane P, in a position rotated through 90° with respect to the configuration shown in Figure 1. This preferred embodiment is shown in Figure 2.

One drawback of the technical solutions described above consists in the fact that these methods for manufacturing three-dimensional articles are particularly long and complex and result in a significant wastage of material.

In order to overcome at least partially these drawbacks, methods for manufacturing three- dimensional articles have been developed where the support element is made by means of an additive manufacturing process which uses:

- a material for additive manufacturing which is different from the material of the three- dimensional article and of inferior quality; and/ or - operating conditions which are different from the operating conditions used for manufacture of the three-dimensional article, for example by using higher feeding speeds of the extrusion device or by varying the sizes of the beads of material to be deposited for forming the layers.

These measures are able to solve only partially the drawbacks mentioned above since the process of manufacturing the support element is still any case long and costly.

Moreover, the variation in the operating conditions during the change-over between the support element and the three-dimensional article has the drawback of making the processes for manufacturing the three-dimensional articles difficult to manage overall.

Furthermore, the measures described above have the further drawback of weakening the support element, reducing its resistance to compression in relation to the layers of material which are deposited for manufacture of the three-dimensional article.

A further drawback consists in the fact that the three-dimensional articles which can be made by means of the known method possess, or possess only to a limited extent, heat insulation or sound insulation properties.

The main object of the present invention is to provide a method for manufacturing three- dimensional articles by additive manufacturing and a three-dimensional article so obtained, which are able to overcome the aforementioned drawbacks.

A particular task of the present invention is to provide a method for manufacturing three- dimensional articles by additive manufacturing which is able to limit material wastage.

A further task of the present invention is to provide a method for manufacturing three- dimensional articles by additive manufacturing which is rapid and has lower costs compared to the methods known in the field.

Another task of the present invention is to provide a method of the type described above which is able to provide the three-dimensional article to be made with a stable support, preferably along curved surfaces of the article which have in particular complex configurations.

A further task of the present invention is to provide a method of the type described above which allows the manufacture of three-dimensional articles having heat and/or sound insulation properties.

Another task of the present invention is to provide a three-dimensional article obtained at least partially by means of deposition of one or more layers of material for additive manufacturing which has heat and/or sound insulation properties.

The object and the main tasks described above are achieved with a method for manufacturing three-dimensional articles by additive manufacturing according to Claim 1 and with a three- dimensional article according to Claim 12.

In order to illustrate more clearly the innovative principles of the present invention and its advantages compared to the prior art, an example of embodiment of the three-dimensional article according to the present invention and of the steps of the method for manufacturing the three-dimensional article according to the present invention will be described below with the aid of the attached figures. In particular, in the figures:

- Figure 1 shows a perspective view of the three-dimensional article described above and realized in accordance with the manufacturing methods known from the prior art;

- Figure 2 shows a perspective view of a particular operating configuration for manufacturing the three-dimensional article described above in accordance with the manufacturing methods known from the prior art;

- Figures 3-6 show perspective views of different steps of the method according to the present invention for manufacturing a three-dimensional article in accordance with a first embodiment;

- Figures 7 and 8 are, respectively, a perspective view and a cross-sectioned perspective view of a three-dimensional article of the present invention in accordance with a second embodiment.

The present description, provided solely by way of a non-limiting illustration of the scope of protection of the invention, relates to a method for manufacturing three-dimensional articles by additive manufacturing and to a three-dimensional article thus obtained.

In particular, the three-dimensional article is denoted overall by the reference number 1, even though in Figures 3-8 and in the continuation of the present description, different embodiments of the article 1 and the method for manufacturing it will be described.

Moreover, the three-dimensional article 1 may have configurations and intended uses which vary from each other, without departing from the scope of the present invention. For example, the three-dimensional article 1 may comprise at least one curved surface or portion 2 with a complex configuration, as shown in Figures 4-6.

Conveniently, the three-dimensional article 1 according to the present invention may be used as a finished product, for example as part of a boat hull, or as a mould for the manufacture of further three-dimensional articles by additive manufacturing, in accordance with the embodiments described below.

The method for manufacturing three-dimensional articles by additive manufacturing according to the present invention comprises mainly the following steps: i) arranging at least one support element 4 on a support plane P, the at least one support element 4 comprising a plurality of surfaces 6A, 6B, 6C; ii) depositing one of more superimposed or adjoining layers of material for additive manufacturing on at least one of the surfaces 6A, 6B, 6C of the support element 4 so as to form at least one shaped member 8 which forms, alone or partly, the manufactured article 1. The at least one shaped member 8 obtained by means of deposition of the layers of material comprises the at least one curved surface 2 with a complex configuration of the three- dimensional article 1 described above.

The support element 4 is intended to support the superimposed or adjoining layers of material for additive manufacturing which will form the at least one shaped member 8.

In particular, the at least one surface 6A of the support element 4 intended to support the layers of material which form the at least one shaped member 8 has a curved profile corresponding to the profile of the shaped member 8 to be made.

With reference to Figures 3-5, the support surface on which the layers of material are deposited is the top surface 6A of the support element 4, while the bottom surface 6B of the support element 4 is the surface placed in contact with the support plane P.

The support element 4 also comprises a plurality of side surfaces 6C which are substantially perpendicular to the horizontal support plane P when the support element 4 is positioned on the support plane P.

The side surfaces 6C are designed to connect the bottom surface 6B with the top surface 6A and their top ends define the top surface 6A.

If the three-dimensional article 1 comprises a plurality of curved surfaces 2 having a particular complex configuration, the step i) may involve the arrangement, on the support plane P, of a number of support elements 4 corresponding to the number of curved surfaces 2 to be formed.

In the continuation of the present description, for the sake of simplicity, reference will be made to the use of a single support element 4, without this thereby unduly limiting the invention.

The deposition step ii) is performed preferably by means of an extrusion device D of a numerical control 3D printer of the type shown in Figure 4.

The extrusion device D is movable above the support plane P by means of suitable movement means, for example of the Cartesian or anthropomorphic type, not shown in the attached figures, in a manner similar to the known machines for additive manufacturing.

Generally, the material for additive manufacturing used in the method for manufacturing three-dimensional articles is a thermoplastic material designed to be heated, melted and extruded before being deposited and is chosen preferably from the group comprising acrylonitrile butadiene styrene (ABS), nylon, polycarbonate, polyether ether ketone (PEEK), polypropylene (PP) and polylactic acid (PEA).

These materials may be used as such or may be reinforced with structural fibres, such as carbon fibres or glass fibres.

The method may also comprise at least one step of machining the at least one shaped member 8 by means of a stock-removal tool T mounted on a machining head.

For example, the machining of the at least one shaped member 8 may comprise the milling and/or drilling and/or finishing and/or smoothing thereof. This machining step performed by the tool T is illustrated schematically in Figure 5.

Conveniently, the numerical control 3D printer may comprise, in addition to the dispensing device D, also the head with the respective tool T for machining the at least one shaped member 8.

Therefore, this type of printing machine is suitable for performing both the deposition of material for obtaining the at least one shaped member 8 and the machining of the shaped member 8.

The method may comprise, downstream of the deposition step ii), a step of removing the at least one shaped member 8 from the support element 4; preferably this removal step is performed downstream of the step for machining the at least one shaped member 8, when the latter is performed by the same printing machine.

The three-dimensional article 1 formed solely by the shaped member 8 removed from the support element 4 is shown specifically in Figure 6; in particular, as shown in Figure 6, the shaped member 8 may be subjected to further machining steps performed on opposite sides of the shaped member 8 and using the tool T described above.

Alternatively, the three-dimensional element 1 is formed by the support element 4 and by the at least one shaped member 8 formed on the support surface 6A of the support element 4. This embodiment of the three-dimensional article 1 corresponds, even though with reference to particular step of the method, to the view shown in Figure 5.

Therefore, in this embodiment, the method does not comprise the step of removing the at least one shaped member 8 from the support element 4 and the at least one shaped member 8 forms part of the three-dimensional article 1.

The three-dimensional article 1 thus obtained is used preferably as a mould for manufacturing further three-dimensional articles by additive manufacturing.

Furthermore, the three-dimensional article 1 may be advantageously used as part of a boat hull.

In a further alternative embodiment, shown in Figures 7 and 8, the method may also comprise the following steps:

- depositing one or more layers of material on a first surface 6A of the support element 4 in order to form a first shaped member 8A;

- depositing one or more layers of material on at least another surface 6B of the support element 4 different from the first surface 6A in order to form a second shaped member 8B.

In this embodiment, the three-dimensional article 1 has a sandwich structure formed by the support element 4 interposed between the shaped members 8A, 8B and the deposition steps correspond substantially to the step ii) indicated above.

Alternatively, the shaped members 8A and 8B may be made separately and then joined to the surfaces 6A and 6B of the support element 4.

In this alternative embodiment the method may comprise the following steps:

- realizing a first shaped member 8B by depositing one or more layers of material for additive manufacturing, possibly on the support plane P;

- joining the first shaped member 8B together with the support element on a first surface 6B of the support element 4;

- depositing one or more layers of material for additive manufacturing on at least another surface 6A of the support element 4 different from the first surface 6B in order to form a second shaped member 8A.

Preferably, in these embodiments, the shaped members 8A, 8B are joined together with and/ or preferably formed respectively on the top surface 6A and on the bottom surface 6B of the support element 4.

In particular, in the embodiment where at least one of the shaped members is joined together with the support element 4, the first shaped member 8B corresponds to the bottom shaped member and is made by depositing the layers of material directly on the support plane P.

Then, the support element 4 is positioned on top of and is joined together with the first shaped member 8B and the other shaped member 8A, namely the top shaped member 8A, is formed by means of deposition of the layers of material onto the top surface of the support element 4.

These embodiments of the method may involve, starting with the sandwich structure of the type described above, further steps of depositing one or more layers of material for additive manufacturing onto the remaining surfaces of the support element 4, namely onto the side surfaces 6C, in order to form further shaped members 8C.

The three-dimensional article 1 thus obtained has a box-like structure formed internally by the support element 4 and externally by the shaped members 8A, 8B, 8C which enclose the support element 4, as shown in Figures 7 and 8.

Therefore, in this embodiment also, the method does not involve the removal of the shaped members 8A, 8B, 8C from the support element 4 and the shaped members 8A, 8B, 8C form part of the three-dimensional article 1.

In accordance with a particular feature of the invention and differently from the methods known from the state of the art, the at least one support element 4 is made of a material different from the material for additive manufacturing with which the at least one shaped member 8 or with which the shaped members 8A, 8B, 8C are made.

In particular, the support element 4 is not made by means of deposition of one or more superimposed or adjoining layers and the material from which it is made is not chosen from the group of thermoplastic materials for additive manufacturing indicated above.

Advantageously, the material of the support element 4 is chosen from within the group comprising paper, cardboard, expanded plastic material, aluminium, light metallic alloys, aramid fibres, resins, fibre resins, cement and gypsum.

Furthermore, the support element 4 has preferably a cellular structure of the type shown in Figures 3 and 8.

In the context of the present description, the expression “cellular structure ’ is understood as meaning a structure formed by cells or chambers or cavities, which are completely closed or open.

This cellular structure is sufficiently strong and particularly light and has a high heat and sound insulation capacity.

The measures regarding the support element 4 indicated above are applicable to all the embodiments of the method described above, irrespective as to whether the three- dimensional article 1 consists of the shaped member 8 removed from the support element 4 or the shaped member(s) 8A, 8B, 8C in combination with the support element 4.

The support element 4 made with one of the materials and with the structure indicated above may be preferably made by means of machining and/ or stock-removal and/ or milling of a block of rough material by means of a machining/ milling head, as shown more clearly in Figure 3.

The machining head may be the same head indicated above with reference to the machining of the at least one shaped member 8, involving where necessary replacement of the tool T depending on the type of machining to be performed and the nature of the material to be machined.

In the embodiments described above in which the three-dimensional article 1 has a box-like or sandwich structure, the cellular structure of the support element 4 does not have the outer skins which generally form the outer layers of a sandwich.

In the embodiment of the three-dimensional article with sandwich structure, the skins are formed by the shaped members 8A, 8B which are obtained by depositing the layers of material for additive manufacturing on the top surface 6A and on the bottom surface 6B of the support element 4.

In the embodiment of the three-dimensional article with box-like structure, the outer skins are formed by the shaped members 8A, 8B, 8C obtained by depositing the layers of material on the surfaces 6A, 6B, 6C of the support element 4.

Preferably, and as shown more clearly in Figures 3 and 8, the cellular structure of the support element 4 is a honeycomb structure with a plurality of hexagonal cells 10 arranged side-by- side.

Advantageously, the step i) of the method involves arranging the support element 4 on the horizontal support plane P so that:

- the walls of the cells 10 are substantially perpendicular to the horizontal support plane P, namely vertical; and

- the open top ends of the cells 10, which are initially without the skin as indicated above, form the support surface 6A on which the layers of material for additive manufacturing are deposited during the step li).

In this configuration, the support element 4 ensures a high compression resistance, and the material for additive manufacturing, during deposition onto the support surface 6A, penetrates into the cells 10 through the open top ends and is firmly secured to the inner walls thereof, forming the skin of the cellular structure.

The skin of the cellular structure thus formed acts as a support for the layers of material which are subsequently deposited in order to form the shaped member 8.

In accordance with a further alternative embodiment (not shown in the figures), the cellular structure of the support element 4 is a structure which has an undulating configuration formed by a plurality of sheets designed to form a plurality of undulating grooves.

The support element 4 is arranged on the horizontal support plane P so that the undulating grooves are substantially perpendicular to the support plane P and therefore extend in the vertical direction.

The invention also relates to a three-dimensional article 1 comprising:

- a core portion 12 comprising a plurality of surfaces 6A, 6B, 6C.

- at least one shaped portion 8 obtained by means of deposition of one or more layers of a material for additive manufacturing on at least one surface 6A of the core portion 12.

In accordance with a further peculiar feature of the invention, the material of the core portion 12 is different from the material used for the additive manufacturing of the at least one shaped portion 8 and the core portion 12 has a cellular structure.

With particular reference to the embodiments of the method described above, in which the shaped member 8 is not removed from the support element 4, in these cases the core portion 12 of the three-dimensional article 1 corresponds substantially to the support element 4, and the at least one shaped portion 8 corresponds to the at least one shaped member 8.

In this connection, in the attached Figures 5, 7 and 8 the reference numbers 4 and 12 must be regarded as being interchangeable for identifying the same element, depending on whether the figures are considered with reference to the method or to the three-dimensional article.

The core portion 12, as already mentioned for the support element 4, comprises a top surface 6A, a bottom surface 6B and side surfaces 6C.

At least one of the top surface 6A and bottom surface 6B may be a curved surface with a complex configuration so that the at least one shaped portion 8 formed thereon also has a corresponding, complex, curved configuration.

Advantageously, the cellular structure of the core portion 12 is a honeycomb structure with a plurality of hexagonal cells 10 arranged side-by-side (see Figures 3 and 8) or a structure with an undulating configuration formed by a plurality of sheets.

The material of the core portion 12 is chosen from the group comprising paper, cardboard, expanded plastic material, aluminium, light metallic alloys, aramid fibres, resins, fibre resins, cement and gypsum.

Figures 4 and 5 show the embodiment in which the three-dimensional article 1 comprises only a shaped portion 8, which may be subjected to machining by means of the tool T (see Figure 5) in combination with the core portion 12.

In the embodiment shown in Figures 7 and 8, the three-dimensional article 1 comprises a plurality of shaped portions 8A, 8B, 8C obtained by depositing the layers of material for additive manufacturing on the surfaces 6A, 6B, 6C of the core portion 12, and therefore also on the side surfaces 6C of the core portion 1, differently from the preceding embodiment.

In this latter embodiment, the three-dimensional article 1 has a box-like structure in which the core portion 12 is enclosed by the shaped portions 8A, 8B, 8C which form the outer skins, in the manner described above with reference to the method.

The shaped portions 8A, 8B, 8C may also be made separately by depositing one or more layers of material for additive manufacturing and then joined together with the respective surfaces 6A, 6B, 6C of the core portion 12.

In an alternative embodiment not shown in the figures, the three-dimensional article 1 comprises only one pair of shaped portions 8A, 8B obtained by depositing one or more layers of material for additive manufacturing on a pair of surfaces of the core portion 12, preferably on the top surface and bottom surface 6A, 6B, so as to form a sandwich structure in which the shaped portions 8A, 8B form the skins of the core portion 12.

From the above description it is now clear how the method and the three-dimensional article according to the present invention are able to achieve advantageously the predefined objects. In particular, the use of a support element, namely a core portion, with a cellular structure is able to simplify the manufacture of the three-dimensional articles and reduce the wastage of material for additive manufacturing.

Furthermore, the cellular structure, both of the honeycomb type and undulating type, provides the three-dimensional article with lightness and increases the heat and sound insulation capacity of the article owing to the cells which contain air.

The various embodiments of the three-dimensional articles which can be obtained by means of the method according to the present invention also have intended uses which vary and are different from each other.

Obviously, the above description of embodiments applying the innovative principles of the present invention is provided by way of example of these innovative principles and must therefore not be regarded as limiting the scope of the rights claimed herein.

Claims

1. Method for manufacturing three-dimensional articles (1) by additive manufacturing, comprising the following steps: i) arranging at least one support element (4) on a support plane (P), said at least one support element (4) comprising a plurality of surfaces (6A, 6B, 6C); ii) depositing one or more superimposed or adjoining layers of a material for additive manufacturing on at least one surface (6A, 6B, 6C) of said support element (4) so as to form at least one shaped member (8); wherein the at least one shaped member (8) forms, alone or in part, the three-dimensional article (1); characterized in that said at least one support element (4) is made of a material which is different from the material for additive manufacturing.

2. Method according to claim 1, characterized in that said support element (4) has a cellular structure.

3. Method according to any one of the preceding claims, characterized in that the material of said support element (4) is chosen from the group comprising: paper, cardboard, expanded plastic material, aluminium, light metallic alloys, aramid fibres, resins, fibre resins, cement and gypsum.

4. Method according to any one of claims 2 and 3, characterized in that said cellular structure is a honeycomb structure formed by a plurality of side-by-side hexagonal cells (10), said support element (4) being arranged on the support plane (P) so that the walls of said cells (10) are substantially perpendicular to the support plane (P) and the open top ends of said cells (10) form the at least one surface (6 A) on which the layers of material for additive manufacturing are deposited during said step ii).

5. Method according to any one of claims 2 and 3, characterized in that said cellular structure is a structure having an undulating configuration and formed by a plurality of sheets designed to form a plurality of undulating grooves, said support element (4) being arranged on the support plane (P) so that the undulating grooves are substantially perpendicular to the support plane (P).

6. Method according to any one of the preceding claims, characterized in that it comprises at least one step of machining said at least one shaped member (8) using a stock-removal tool (T).

7. Method according to any one of the preceding claims, characterized in that it comprises, downstream of said step ii), a step of removing said at least one shaped member (8) from said support element (4), the three-dimensional article (1) being formed by said at least one shaped member (8).

8. Method according to any one of claims 1 to 6, characterized in that the three-dimensional article (1) is formed by said support element (4) and by said at least one shaped member (8).

9. Method according to any one of claims 1 to 6, characterized in that it comprises the following steps:

- depositing one or more layers of material on a first surface (6A) of the support element (4) for realizing a first shaped member (8A);

- depositing one or more layers of material for additive manufacturing on at least another surface (6B) of said support element (4) different from said first surface (6A) for realizing a second shaped member (8B); wherein the three-dimensional article (1) has a sandwich structure formed by said support element (4) interposed between said first and said second shaped members (8A, 8B).

10. Method according to any one of claims 1 to 6, characterized in that it comprises the following steps:

- realizing a first shaped member (8B) by depositing one or more layers of material for additive manufacturing;

- joining said first shaped member (8B) together with said support element (4) on a first surface (6B) of the support element (4);

- depositing one or more layers of material for additive manufacturing on at least another surface (6A) of said support element (4) different from said first surface (6B) for realizing a second shaped member (8A); wherein the three-dimensional article (1) has a sandwich structure formed by said support element (4) interposed between said first and second shaped members (8A, 8B).

11. Method according to any one of claims 9 and 10, characterized in that it comprises further steps of depositing one or more layers of material for additive manufacturing on the remaining surfaces (6C) of said support element (4) for realizing respective shaped members (8C), said three-dimensional article (1) having a box-like structure formed by said support element (4) enclosed inside said shaped members (8A, 8B, 8C).

12. Three-dimensional article (1) comprising:

- a core portion (12) comprising a plurality of surfaces (6A, 6B, 6C);

- at least one shaped portion (8) obtained by deposition of one or more layers of material for additive manufacturing on at least one surface (6A) of said core portion (12); characterized in that the material of said core portion (12) is different from the material for additive manufacturing of said at least one shaped portion (8), said core portion (12) having a cellular structure.

13. Article (1) according to claim 12, characterized in that the cellular structure of said core portion (12) is a honeycomb structure.

14. Article (1) according to claim 12, characterized in that the cellular structure of said core portion (12) is an undulating structure.

15. Article (1) according to any one of claims 12-14, characterized in that the material of said core portion (12) is chosen from the group comprising paper, cardboard, expanded plastic material, aluminium, light metallic alloys, aramid fibres, resins, fibre resins, cement and gypsum.

16. Article (1) according to any one of claims 12-15, characterized in that it comprises at least one pair of shaped portions (8A, 8B) obtained by depositing one or more layers of material for additive manufacturing respectively on a pair of surfaces (6A, 6B) of said core portion (12), said three-dimensional article (1) having a sandwich structure wherein the shaped portions (8 A, 8B) form the skins of said core portion (12).

17. Article (1) according to any one of claims 12-15, characterized in that it comprises a plurality of shaped portions (8A, 8B, 8C) obtained by depositing one or more layers of material for additive manufacturing on the surfaces (6A, 6B, 6C) of said core portion (12), said three-dimensional article (1) having a box-like structure wherein the core portion (12) is enclosed by the shaped portions (8A, 8B, 8C) which form the outer skins.