Patent Description:
Three-dimensional printing systems have been known for several decades, and have become increasingly widespread, for the production, using additive production techniques, of three-dimensional objects formed by laying one on the other a succession of layers of suitable materials in a liquid or semi-liquid or molten state, which are configured to solidify after being deposited.

The first three-dimensional printer models made available on the market provided a printing head that was moved following a predefined path, releasing a semi-liquid substance so as to form a layered structure with it. For this purpose, the printing head is mounted mobile inside a generally closed support structure.

These printer models, also called fixed, were generally configured to be used in a single location, generally inside a dedicated office or studio. These models made it possible to print only objects of limited size and in any case limited by the sizes of the cavity defined by the support structure, inside which the printing head can move. This limit was relative both to the longitudinal sizes and also to the lateral sizes, that is, those perpendicular to the axis of development.

In order to be able to print larger objects, three-dimensional printing systems have been developed over time in which the printing head is mounted at the end of a robotic articulated arm, which allows a greater height of the objects, and also increased lateral sizes. However, even this type of three-dimensional printer is subject to limitations in the sizes of the objects. For example, they are not able to create structures of a size comparable to those of houses or larger buildings.

Alternatively, so-called mobile printing systems have also been developed, that is, they are not constrained inside a fixed support structure. These three-dimensional printers generally comprise an articulated arm mounted on a mobile base, for example equipped with wheels or belts. The printing head is mounted at the free end of the articulated arm.

This type of printer has made it possible to create three-dimensional objects in situ, that is, directly on a place of interest, for example a construction site.

However, even these printer models suffer from a limitation in the sizes of the objects that can be produced, in particular their height, which is in any case limited by the maximum extension of the robotic arm that carries the printing head.

Three-dimensional printing systems are also known for the on site construction of houses or buildings, which provide a modular support structure, in which each module has sizes of several meters, so as to be able to potentially print a building or part of it (such as for example one floor of the building). These printing systems have the limit that the support structure has to be assembled and disassembled every time a new building is to be built.

A more recent type of three-dimensional printing system is configured to rest and move directly on the object being printed. In this way it is possible to at least increase the vertical sizes of the objects that can be printed.

For example, <CIT> shows a mobile three-dimensional printing system mounted on a mobile support equipped with a pair of wheels that engage in corresponding racks made inside the object being printed. However, this solution entails a constraint in the internal section of the object, which must be such as to allow a correct interaction between each of the wheels of the support and the corresponding racks, and therefore constant to maintain this interaction along the whole object. In particular, the internal section of the object being printed must not exceed a predetermined value, which entails a limitation in the lateral sizes of the object. Another limitation of this system is that it is configured to deliver concrete only.

<CIT> describes a three-dimensional printing system equipped with a printer mounted on a movement mechanism that comprises three toothed wheels. The printer is configured to print an object equipped with racks to interact with the toothed wheels. The printer is contained in a closed structure with limited lateral sizes, which also limits the lateral sizes of the object to be printed. Furthermore, the system in this document is designed to function in space or in any case in environments with microgravity or in zero gravity, and in practice cannot function correctly in environments with earth pressure.

<CIT> describes a three-dimensional printing system comprising a printer mounted on a movement mechanism configured to be rested on the external surface of the object being printed. To this purpose, the system provides four wheels mounted on respective arms and pressed, during use, against the surface of the object by corresponding pressure means. However, this does not allow to guarantee at all times, and under all conditions, a perfect grip of the wheels on the object being printed.

<CIT> discloses a three-dimensional printing system comprising a printer and a three-dimensional object printed by the printer. The object is provided with a guide rail which is not printed together with the object, but is attached thereto. The guide rail is configured to house sliding a support slipper of the printer. Having the guide rail as a separate element entails the need of attaching it to the printed object while it is stamped, thereby requiring to stop the printing process.

There is therefore a need to perfect a three-dimensional printer and a method to produce a three-dimensional object that can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide a three-dimensional printer that is able to print three-dimensional objects of even greater sizes than those already obtainable, in particular along the axis of development of the object.

Another purpose of the present invention is to provide a three-dimensional printer that can function with any type of printing substance or material.

Yet another purpose is to provide a three-dimensional printer that can be adapted to any sector in the state of the art, and which is able to print any type of object.

Another purpose is to provide a three-dimensional printer that is connected in a stable and safe manner to the object being printed.

Another purpose is to perfect a method to produce a three-dimensional object, by means of three-dimensional printing, that allows to create three-dimensional objects without constraints of size, in particular along the longitudinal axis of development.

Yet another purpose is to perfect a method to produce a three-dimensional object, by means of three-dimensional printing, that allows to ensure a good interaction between the printer and the object being printed in any operating condition.

It is also a purpose of the present invention to obtain, by means of said method and using said printer, a three-dimensional object able to interact with the three-dimensional printer in order to obtain the purposes described above.

In accordance with the above purposes, Applicant has developed a three-dimensional printing system and perfected a method to produce three-dimensional objects, which overcome the limits of the state of the art and eliminate the defects present therein.

The inventive idea underlying the present invention is to make the printer move on the three-dimensional object itself, while it is produced, through a guide and retention system integrated in the three-dimensional object to be printed. With the term "integrated" we mean that the guide and retention system is made in a single piece with the three-dimensional object in question.

For this purpose, the printer, which is of the mobile type, is equipped with a movement system comprising one or more contact elements and one or more abutment elements configured to respectively come into contact with the guide element and the retention element which are integrated in the object being produced.

It is provided to produce one or more guide elements and one or more retention elements on the three-dimensional object, which are integrated in the object itself and are configured to interact respectively with the contact elements and the abutment elements of the printer in such a way as to allow it to move on the object being produced.

According to one aspect, there is provided a method to produce a three-dimensional object as in claim <NUM>, by means of three-dimensional printing. The three-dimensional object comprises one or more guide elements integrated in at least one external lateral surface of the printed object, each equipped with at least one retention element. Advantageously, the method provides that the printing is performed by means of a mobile three-dimensional printer comprising one or more support members each equipped with a respective contact element configured to come into contact with a guide element of the three-dimensional object, and provided with at least one abutment element configured to interact with the at least one retention element. This interaction allows to retain the support member in the vicinity of the lateral surface of the printed object.

Advantageously, the retention element comprises an abutment surface inclined with respect to the lateral surface of the printed object and oriented toward it. Conversely, the abutment member also comprises an abutment surface inclined with respect to the support member and oriented toward it. The abutment surface of each retention element is configured to come into contact with an abutment surface of each abutment member.

In accordance with some embodiments, the retention element comprises at least one fin that extends from the lateral surface of the object, preferably a pair of fins. Advantageously, the fin has an extremal portion inclined with respect to the lateral surface of the object.

The method provides to print, at the same time as the three-dimensional object, one or more guide elements integrated in the three-dimensional object. The guide elements are configured to interact with the contact element of the support member of the three-dimensional printer. The guide elements are provided with retention elements integrated in at least one external lateral surface of the three-dimensional object and configured to interact with at least one abutment member in such a way as to retain the onre or more support memners in the vicinity of the lateral surface of the three-dimensional object and maintain the contact elements inContact with the guide elements. In accordance with some embodiments, the three-dimensional object comprises a plurality of lateral surfaces, and a plurality of guide elements and retention elements integrated in the lateral surfaces.

By lateral surface we mean a surface that extends, at least partly, along a plane that is parallel, or substantially parallel, to a homologous plane passing through the longitudinal axis of development of the object.

At least one guide element and at least one retention element are integrated in the lateral surface of the three-dimensional object. In the event that the three-dimensional object is equipped with several lateral surfaces, it is advantageous to provide a guide element and a retention element integrated in each of them.

In a preferential way, the method provides at least one step of displacing the three-dimensional printer on the three-dimensional object during its formation, by means of printing. More preferentially, the displacement of the three-dimensional printer on the three-dimensional object occurs by means of the interaction between the contact elements and the guide elements.

In accordance with some embodiments, the guide elements are oriented in such a way as to be parallel to the axis along which the lateral surface develops, that is, substantially parallel to the axis of development of the three-dimensional object.

In accordance with some embodiments, the guide element is of the continuous type, that is, configured to allow a continuous displacement of the three-dimensional printer. A continuous guide element can comprise, for example, at least one rack. In these embodiments, the contact element can be configured as a toothed wheel.

According to alternative embodiments not covered by the invention, the guide element is of the discrete type. In this case, the object comprises a plurality of discrete guide elements. These are advantageously disposed along a predetermined path on the lateral surface of the object being formed.

In accordance with some embodiments, the guide element comprises two racks located parallel to each other made on as many lateral surfaces, which can be contiguous and adjacent, or opposite.

In a preferred embodiment, the object comprises a plurality of lateral surfaces, contiguous to each other in such a way as to form a closed perimeter profile; there being provided a guide element made on each lateral surface.

Preferably, all the guide elements are the same and parallel to each other.

In accordance with other embodiments, the three-dimensional object comprises at least one guide element of the continuous type and at least one guide element of the discrete type.

According to another aspect, there is provided a three-dimensional printing system as in claim <NUM>, comprising a three-dimensional printer provided with at least one mobile support device, and a three-dimensional object provided with one or more guide elements that each comprise at least one retention element integrated in at least one external lateral surface thereof, and produced by means of the three-dimensional printer.

The three-dimensional printer is configured to move on the three-dimensional object during its production.

More precisely, the mobile support device is configured to interact with one or more guide elements of the object to allow the displacement of the three-dimensional printer on the three-dimensional object.

The mobile support device comprises one or more support members, each provided with one or more contact elements and at least one abutment member. The guide and retention systems, in turn, are configured to interact with the contact elements and each comprise at least one retention element configured to interact with the abutment members, in such a way as to retain the one or more support members in the vicinity of the lateral surface of the three-dimensional object and maintain the contact elements in contact with the guide elements. The guide elements are made in a single piece with the three-dimensional object.

It is understood that elements and characteristics of one embodiment can conveniently be combined or incorporated into other embodiments without further clarifications.

<FIG> shows a printing system, comprising a three-dimensional printer indicated as a whole with reference number <NUM>. The three-dimensional printer <NUM> is of the mobile type, that is, it does not have a fixed support structure. Generally, the three-dimensional printer <NUM>, or 3D printer, is configured to produce a three-dimensional object <NUM> by means of additive manufacturing techniques. The three-dimensional printer <NUM> comprises a bearing structure <NUM> on which a printing head <NUM> is mounted mobile.

The three-dimensional object <NUM> is provided with at least one integrated guide and retention system, which is produced at the same time as the three-dimensional object <NUM> itself, during printing. The guide and retention system comprises at least one guide element <NUM> and at least one retention element <NUM>. Vice versa, the three-dimensional printer <NUM> is provided with a movement system configured to interact with the guide and retention system of the printed object. This movement system comprises one or more contact elements <NUM> and one or more abutment members 46A.

The three-dimensional printer <NUM> provides a mobile support device <NUM> (<FIG>) configured to interact with the guide element <NUM> of the three-dimensional object <NUM> and with the retention element <NUM>.

More precisely, the mobile support device <NUM> comprises a support member <NUM>, connected to the bearing structure <NUM> of the 3D printer <NUM>, and a contact element <NUM> attached to the support member <NUM>. The interaction between the 3D printer <NUM> and the three-dimensional object <NUM> occurs by means of the contact element <NUM> and the guide element <NUM> (<FIG>).

In particular, the 3D printer <NUM> is able to form the object <NUM> by depositing successive layers of the printing material through the printing head <NUM>, according to modes known in the state of the art.

The 3D printer <NUM> deposits the printing substance or material on a plane, which identifies a base plane, indicated by the letter P in <FIG>, delivering the printing material along a predetermined path that defines a layer of the object <NUM>.

The object <NUM> is produced by placing a plurality of successive layers, thus defining an axis of development A of the object <NUM>, typically perpendicular to the base plane P (<FIG> and <FIG>).

In the embodiments shown in the attached drawings, the base plane P is a substantially horizontal plane X-Y, while the axis of development A is substantially vertical and parallel to the vertical direction Z.

The printing head <NUM> is suitably connected to a source of printing substance or material, not shown in the drawings. The printing substance can be of any type whatsoever, for example a heated polymer, building material, metal powders, concrete, a mixture thereof, or others.

The bearing structure <NUM> can comprise a frame <NUM> suitably shaped in such a way as, for example, to define a printing zone within which the printing head <NUM> can move. In the example shown, the frame <NUM> has a rectangular shape; however, other shapes can be provided. More generally, the shaped frame <NUM> has a shape such as to have a geometric center, which advantageously is comprised on the axis of development A of the object <NUM>.

The frame <NUM> supports a movement mechanism <NUM> to which the printing head <NUM> is connected in order to move the latter. It should be noted that, preferably, the movement mechanism <NUM> is configured in such a way as to give the printing head <NUM> at least two degrees of freedom in space, more preferably three degrees of freedom. In this way, the printing head <NUM> is able to move in the directions X-Y in such a way as to be able to cover the entire base plane P, and in the direction Z. In this way, after finishing depositing one layer, the movement mechanism <NUM> is driven in order to move the printing head <NUM> along the axis Z in such a way as to modify the vertical height of the printing head <NUM>, for example raising it by the appropriate amount to allow it to deposit the next layer on top of the layer just formed.

According to the embodiment shown in the attached drawings, the movement mechanism <NUM> can comprise, for example, a pair of first guides <NUM> parallel to each other, and at least one second guide <NUM> perpendicular to the first guides <NUM>. The second guide <NUM> is advantageously mounted sliding on the first guides <NUM>, and is equipped with a motor member <NUM> so that it can be displaced along the first guides <NUM> (<FIG>).

The printing head <NUM> is conveniently mounted sliding on the second guides <NUM> and is provided with its own motor member <NUM> so that it can be displaced along the same second guides <NUM>.

It can be surmised from the structure of the movement mechanism <NUM> that the movement of the printing head <NUM> is mainly contained in a movement plane which, during use, is advantageously parallel to the base plane P and therefore perpendicular to the axis of development A of the object <NUM>.

Preferably, the 3D printer <NUM> comprises a control unit <NUM> to which the motor members <NUM>, <NUM> are connected and which allows the individual and/or coordinated drive thereof. The control unit <NUM> can also be configured to command the delivery of the printing material.

The bearing structure <NUM> comprises one or more mobile support devices <NUM>. In the example of <FIG>, four mobile support devices <NUM> are provided, each comprising a support member <NUM> configured to rest on a lateral surface <NUM> of the object <NUM> and each connected to a respective side of the shaped frame <NUM> (<FIG> and <FIG>). Obviously, there can be any number whatsoever of mobile support devices <NUM> according to the geometry of the frame <NUM> and/or the three-dimensional object <NUM> to be produced. It is preferable that the mobile support devices <NUM> are in a number and disposition such as to ensure a stable balance for the 3D printer <NUM> when it moves along the object <NUM>.

For example, in the embodiment shown in the drawings, the object <NUM> has a substantially rectangular plan and comprises four lateral surfaces <NUM>. The 3D printer <NUM> is equipped with four mobile support devices <NUM>, each of which comprises a support member <NUM> provided to rest against a respective lateral surface <NUM> of the object <NUM>. A smaller number of mobile support devices <NUM>, for example two or three, can also be provided, provided that they are such as to ensure the stability of the 3D printer <NUM> while it rests on the object <NUM>.

In accordance with some embodiments, the support members <NUM> are connected to the frame <NUM> by means of a fixed support <NUM> connected directly to the frame <NUM> and, preferably, with an elongated shape. In a preferential way, the fixed support <NUM> projects outside the frame <NUM> and is oriented perpendicularly with respect to the side of the frame <NUM> from which it departs.

The support members <NUM> are preferably mounted sliding on their fixed supports <NUM>, for example they are each mounted on a respective slider <NUM> sliding along its own fixed support <NUM> (<FIG>) and moved by means of a corresponding motor member 44A advantageously connected to the control unit <NUM>.

The slider <NUM> is favorably equipped with at least one guide rod <NUM> (in the example shown in <FIG>, each slider <NUM> comprises two guide rods <NUM>) on which a respective support member <NUM> is mounted sliding. Advantageously, the guide rods <NUM> are oriented substantially parallel to the axis of development A, in such a way as to allow the displacement of the support members <NUM>, relative to the bearing structure <NUM>, in the same direction.

This allows to displace the bearing structure <NUM> with respect to the support members <NUM>, thus displacing the printing head <NUM> along the axis Z, in addition to the movement in the plane X-Y.

The support members <NUM> are preferentially disposed below the bearing structure <NUM>, more preferentially below the printing head <NUM>.

In the example shown in the attached drawings, the object <NUM> is equipped with guide elements <NUM> of the continuous type. Each guide element comprises a pair of racks <NUM> disposed parallel to each other (<FIG>). In an advantageous way, the racks <NUM> are reciprocally distanced and a retention element is provided between them consisting of a pair of fins <NUM> which extend transversely from the lateral surface <NUM> of the object <NUM>. Each pair of fins <NUM> defines a respective guide groove <NUM>.

The fins <NUM> can be perpendicular with respect to the lateral surface <NUM> of the object <NUM>, or, as shown in the drawings, have at least one portion inclined toward the guide groove <NUM>. In this way, the surface 32A of the fins <NUM> facing toward the inside of the guide groove <NUM> acts as an abutment for a possible abutment member 46A to be inserted inside the guide groove <NUM>, allowing a more stable and secure connection of the support member <NUM> to the guide element <NUM>. The surface 32A therefore acts as an abutment surface.

It should be noted that, in correspondence with the guide elements <NUM>, the thickness of the lateral surfaces <NUM> of the object <NUM> can be increased with respect to the rest of the object <NUM>, in order to strengthen the guide elements <NUM> (<FIG>).

Each support member <NUM> comprises at least one contact element <NUM>, preferably facing toward the object <NUM> during use. In particular, in the example shown, the support member <NUM> comprises a body with an elongated shape oriented perpendicularly, or substantially perpendicularly, to the corresponding lateral surface <NUM> of the object <NUM>. The contact element <NUM> is located in correspondence with the free end of the body that faces toward the object <NUM>.

As can be surmised from <FIG>, each support member <NUM> comprises a pair of contact elements <NUM>, which in this example are toothed wheels, each configured to cooperate with a respective rack <NUM> (<FIG>). The toothed wheels <NUM> are rotatably mounted on their respective support member <NUM>.

The toothed wheels <NUM> can each be equipped with a respective motor member 42A (<FIG> and <FIG>) for their movement. The motor members 42A can be connected to the control unit <NUM>, in order to synchronize their movement and thus keep the 3D printer <NUM> oriented in the plane X-Y.

In the example shown, the support members <NUM> each comprise an extremal element <NUM> (<FIG> and <FIG>) which protrudes from the end of the body where the contact element <NUM> is located, and is configured to be inserted in the guide groove <NUM> determined by the fins <NUM>. In particular, the extremal element <NUM> can comprise at least one, preferably at least two, abutment members 46A configured to come into contact with the internal surfaces 32A of the fins <NUM>, as explained above. In particular, the extremal element <NUM> is configured substantially in the shape of a V, with two abutment members 46A that extend away from each other (<FIG>). Each abutment member 46A has its own abutment surface 46B oriented toward the respective support member <NUM>, and preferably inclined with respect thereto.

In particular, the abutment surface 46B can be inclined with respect to the external surface 41A of the support member <NUM> by an angle comprised between <NUM>° and <NUM>°. It can also be provided that the abutment surface 46B is parallel to the external surface 41A of the support member <NUM>, in particular the surface of its free end facing the lateral surface <NUM> of the printed object <NUM>. In this case, the abutment member 46A is advantageously configured in the shape of an L. Likewise, the surface 32A of the fins <NUM> is also preferably made parallel to the external surface <NUM> of the printed object <NUM>, for example by means of an L-shaped configuration.

As can be seen in <FIG>, the interaction between the surface 32A of each of the fins <NUM> and the abutment surfaces 46B of the abutment members 46A allows to retain the support member <NUM>, and therefore also the toothed wheels <NUM>, in the proximity of the lateral surface <NUM> of the printed object <NUM>, and therefore also of the respective guide element <NUM>. This guarantees that each toothed wheel <NUM> remains engaged with its respective rack <NUM>, thus ensuring an optimized displacement of the printer <NUM> on the printed object.

The guide elements <NUM> are disposed externally on the lateral surfaces <NUM> of the object <NUM>, and the contact elements <NUM> are oriented in such a way as to face the guide elements <NUM> in order to be able to correctly cooperate with the latter.

It should be noted that, in the example shown, in the guide elements <NUM> the racks <NUM> are disposed externally to the fins <NUM> that form the guide groove <NUM>. The surfaces 32A of the two fins <NUM> face toward the guide groove <NUM> so as not to interfere with the toothed wheels <NUM>.

It is possible to provide a configuration in which, for example, the fins are inclined toward the outside with respect to the groove <NUM>, and that a single rack <NUM> is provided located between the two fins <NUM>, that is, precisely in the groove <NUM>. Obviously, in this case the corresponding support member <NUM> has a single toothed wheel <NUM> in a substantially centered position and two abutment members 46A positioned on each side of the toothed wheel <NUM> and inclined toward it, in such a way that the abutment surfaces 46B are parallel to the surfaces 32A of the fins <NUM>.

Furthermore, it should be noted that, in the example shown, the guide elements <NUM> are rectilinear and oriented longitudinally to the axis of development A. However, it is possible to provide that the guide elements <NUM> are oriented transversely, perpendicularly or inclined with respect to the axis of development A, or that they have at least one longitudinal segment and at least one transverse segment.

It should also be noted that the guide elements can differ from each other, for example one can be of the continuous type and another of the discrete type, or that each guide element can have a continuous part and a discrete part.

The functioning of the 3D printer <NUM> provides to print the object <NUM> already provided with the guide elements <NUM> integrated.

The printing occurs in a known way, for example by means of additive manufacturing techniques. The guide elements <NUM> are created progressively, layer by layer, together with the object <NUM> itself.

For this purpose, the printing head <NUM> is moved in the movement plane until one layer of the object <NUM> is completed, then it is displaced along the axis Z by a distance such as to be able to print the next layer. For example, the distance of the displacement along the axis Z can correspond to the thickness of one layer.

In an initial phase of the formation of the object <NUM>, during which the guide elements <NUM> are not yet sufficient to allow the 3D printer <NUM> to move on the object <NUM>, the displacement of the printing head <NUM> in the direction Z is performed by displacing the bearing structure <NUM> with respect to the support members <NUM>, which rest on the base plane P.

Once the guide elements <NUM> have been formed sufficiently to allow the contact elements <NUM> to interact with them, the 3D printer <NUM> can move on the object <NUM>, as shown in <FIG> and <FIG>.

In the case of guide elements <NUM> of the continuous type, as in the example shown in the drawings, the displacement of the 3D printer <NUM> along the object <NUM> occurs by moving the toothed wheels <NUM> that cooperate with the racks <NUM>.

In the case of guide elements <NUM> of the discrete type, not covered by the claims, the displacement of the 3D printer <NUM> along the object <NUM> occurs by displacing the support members <NUM> with respect to the bearing structure <NUM>, in such a way that they reach a respective discrete guide element. The support members <NUM> are advantageously displaced one at a time, or in any case in such a way that at least two of them remain in contact with the object <NUM>, in order to ensure a correct balance of the 3D printer <NUM> during its displacement.

Variations in the lateral sizes of the object <NUM> can be compensated for by displacing one or more of the sliders <NUM> along its fixed support <NUM>.

Claim 1:
Method to produce a three-dimensional object (<NUM>), by means of a mobile three-dimensional printer (<NUM>) comprising one or more support members (<NUM>) each equipped with a respective contact element (<NUM>) configured to come into contact with the three-dimensional object (<NUM>) and each equipped with at least one abutment member (46A), comprising the step of printing said three-dimensional object (<NUM>), characterized in that it comprises the step of printing said three-dimensional object (<NUM>) and simultaneously of printing one or more guide elements (<NUM>), integrated in at least one external lateral surface (<NUM>) of said three-dimensional object (<NUM>), configured to interact with said contact elements (<NUM>) and provided with retention elements (<NUM>) integrated in the at least one external lateral surface (<NUM>) of said three-dimensional object (<NUM>), characterized in that the retention elements (<NUM>) are configured to interact with said at least one abutment member (46A) in such a way as to retain said one or more support members (<NUM>) in the vicinity of said lateral surface (<NUM>) of the three-dimensional object (<NUM>) and maintain said contact elements (<NUM>) in contact with said guide elements (<NUM>).