WO2012150497A1

WO2012150497A1 - Perfected method for manufacturing three-dimensional objects in layers and perfected stereolithography machine using said method

Info

Publication number: WO2012150497A1
Application number: PCT/IB2012/000873
Authority: WO
Inventors: Sergio Zenere
Original assignee: Dws S.R.L.
Priority date: 2011-05-03
Filing date: 2012-05-03
Publication date: 2012-11-08
Also published as: ITVI20110115A1

Abstract

The invention is a method for making three-dimensional objects (O) formed by a plurality of superimposed layers (L) of a fluid photopolymer (R) suited to solidify through polymerization following a stimulating action, comprising the following operations: - making the fluid photopolymer (R) flow on a supporting surface exposed to stimulation in such a way as to define a layer (L) adjacent to the previous layer (L); - selectively exposing the layer (L) to stimulation in one or more predefined areas (K); - repeating the step regarding flow and exposure for each successive layer (L) of the three-dimensional object (O). The method also includes an operation intended to reduce pressure in the environment where the three-dimensional object (O) is manufactured compared to the external atmospheric pressure, prior to said operations regarding flow and exposure.

Description

PERFECTED METHOD FOR MANUFACTURING THREE-DIMENSIONAL OBJECTS IN LAYERS AND PERFECTED STEREOLITHOGRAPHY MACHINE USING SAID METHOD.

DESCRIPTION

The present invention concerns a perfected method for manufacturing three-dimensional objects in layers, which in technical jargon is known as "stereolithography".

The present invention also concerns a stereolithography machine employing said method.

As is known, stereolithography is extensively used for rapidly prototyping three-dimensional, even complex objects, as it allows said objects to be manufactured in a very short time and practically with no need to use special equipment.

In general, the stereolithography technique includes a first virtual division of the geometry of the object to be reproduced in layers having a predefined thickness, which are then actually produced by a stereolithography machine that places them one on top of the other in order to create the object.

The layers are made of a fluid substance that can solidify under the effect of suitable stimulation.

Said fluid substance is preferably but not necessarily a resin in the liquid state. It is also known that there are two macro types of stereolithography machines M available on the market, schematically represented in Figure 1 and in Figure 2, respectively, for the rapid prototyping of three-dimensional objects using fluid substances R.

Both types comprise a tank V that contains the fluid substance R to be subjected to stimulation, a modelling head T that can move along a direction substantially orthogonal to the bottom F of the tank V and is provided with a plate P having the function of supporting the object being made.

Furthermore, both the stereolithography machines M are provided with an emitter device E, typically a laser source, facing said plate P in such a way as to stimulate the layer of the fluid substance R that is closest to it in order to activate its polymerization and solidification process.

In a first macro type of stereolithography machines of the known art, shown in Figure 1 , the emitter device E is placed above the tank V, which must contain a quantity of fluid substance R at least equal to the height of the object to be made.

In this type of machine the plate P is initially positioned so that its upper surface is covered by a layer of the fluid substance R whose thickness is equal to the thickness of the base layer of the object to be made.

Thus, said layer of fluid substance R is subjected to stimulation in the areas corresponding to the volume of the object to be produced, so as to solidify them and make them adhere to the plate P.

The plate P is then lowered until the just stimulated layer of the object is submerged by a layer of the fluid substance R whose thickness is equal to the thickness required for the successive layer, which again is subjected to stimulation, always in the areas corresponding to the volume of the object to be produced.

The process for manufacturing the three-dimensional object proceeds analogously for the successive layers, with the plate P being progressively lowered.

In the second macro type of stereolithography machines shown in Figure 2, instead, the emitter device E is positioned under the tank V and furthermore the bottom F of the same tank V is made of a transparent material, so that the layer of the fluid substance R that is closest to the bottom F is stimulated.

For this reason, the plate P is initially placed in proximity to the bottom F and spaced from the latter of a distance equal to the thickness of one layer of the object to be made.

At this point, the fluid substance R, which is positioned between the lower surface of the plate P and the bottom F, is selectively exposed to the stimulation generated by the emitter device E that determines the polymerization of the same fluid substance R in the areas corresponding to the volume of the object to be made, which solidify and adhere to the plate P.

Successively, the head T is lifted together with the first solidified layer of the object, until it emerges from the fluid substance R, so as to allow complete levelling of the latter inside the tank V.

After that the plate P is immersed in the fluid substance R again, so that between the previously solidified layer and the bottom F there is a quantity of fluid substance R equal to the thickness of the successive layer to be solidified through a further selective exposure. Said operations just described above are repeated for each layer of the object to be made, until its completion. The methods for making three-dimensional objects implemented with both types of stereolithography machine M of the known art described above pose some common drawbacks, determined by the fact that said operations are carried out in an environment at atmospheric pressure.

More precisely, for both types of stereolithography machine M and the relevant methods for making three-dimensional objects, a first drawback, due to the presence of air at atmospheric pressure in the operating environment, lies in the risk that air bubbles may get entrapped between the layers of the fluid substance R, when the head T and the plate P are moved along their direction of movement.

In fact, during the production of the three-dimensional objects, independently of whether the head T is lowered, as in the case of the first type of stereolithography machine M described above, or the head T is lifted, as in the case of the second type of stereolithography machine M of Figure 2, the flow of the fluid substance R over or under the plate P may cause air bubbles to be entrapped within the layers of the same fluid substance R that must successively be stimulated by means of the emitter device E.

Consequently, there may be the drawback that one or more layers of the three- dimensional object have in their inner volume some empty spaces that negatively affect the quality of the objects made and their stability over time. This disadvantageous effect is known in technical jargon as "foam effect".

A further drawback, common to both types of stereolithography machine M described above, lies in that, proceeding with the production of said objects in an environment at atmospheric pressure, there is a high heat exchange coefficient. Said effect may disadvantageously generate a high thermal gradient between the various superimposed layers of the fluid substance R and/or between the various areas belonging to the same layer, for example between the centre areas and the peripheral areas of each individual layer. This high thermal gradient in turn leads to different results of the polymerization process in the different areas of one same layer of the fluid substance R, like non-homogeneous solidification and instability of the three- dimensional model over time.

A further drawback, common to both types of stereolithography machine described above and to the relevant methods, lies in that the presence of air, of oxygen in particular, at atmospheric pressure in direct contact with the fluid substance R determines a slowdown in its solidification process, consequently prolonging the time necessary to make the three-dimensional object.

It is also known that a second type of drawbacks, always determined by the production of three-dimensional objects in an atmospheric environment, concerns exclusively the stereolithography machines belonging to the second macro type, described above and shown in Figure 2, and the respective method.

In fact, a first specific drawback of this last type of stereolithography machine may take place when objects are made that have one or more cavities in their inner part, as in the case of a tight empty sphere. In this case, when the head

T is lifted from the fluid substance R following the solidification of one or more layers, the air present in the tank V tends to flow under the plate P and get in the above mentioned cavities in the object being made.

Proceeding, successively, to lower the head inside the tank V, that is, when the plate P is immersed again in the fluid substance R, the air present in said cavities is compressed between the same already solidified layers and the bottom F of said tank V.

Disadvantageous^, in turn, the compressed air exerts a thrusting action on the underlying fluid substance R, causing it to be displaced towards the side walls of the plate P.

In this way, to disadvantage, there may be a lack of fluid substance R at the level of the areas of the layer to be solidified, thus causing a lack of material in the final object.

At present in the known art, in order to overcome this drawback, the object being made is provided with holes, properly located on its surface, in order to release said excessive pressures.

However, said solution disadvantageous^ requires more time, both because it is necessary to modify the file of the object to be made and because when the production of the object has been completed it is necessary to close the holes previously made.

Furthermore, it is known that another drawback occurs when the head T is lifted together with the other solidified layers that have adhered to one another and to the plate P. This drawback is the so-called "suction effect", well known to the experts in this field, which consists of a traction force that opposes the lifting of the head T and the detachment of the already solidified layers of the object from the fluid substance R in which they are immersed.

It is known that in order to be able to avoid the negative consequences related to said suction effect, among which there are the breakage of the three- dimensional object and its detachment from the plate P, in the known art the manufacturing step includes an increase in the number and thickness of the special supports of the object that are normally used in stereolithography.

According to the production techniques of three-dimensional objects, in fact, supports are applied to the same object in order to support its projecting parts and to counteract said traction force during the lifting of the head T. It is also known that the size and number of the supports depend on the effort (traction force) exerted by the plate P during the lifting step.

However, disadvantageous^, the higher the number of supports applied to the object, the more complicated the design of the latter, which consequently increases costs and production time.

Furthermore, the supports cannot be reused for the production of other objects and therefore are wasted, thus further increasing the cost of the object.

Furthermore, when the object to be manufactured is particularly complicated, it is not possible to produce the supports, which actually limits the applicability of the stereolithography method.

According to a known technique, the supports are produced by the stereolithography machine at the same time as the three-dimensional object, thus making up an integral part of the latter.

Obviously, in addition to the drawbacks already described, the above mentioned technique poses a further drawback, represented by the fact that it is necessary to remove the supports mechanically, with a consequent further increase in the cost of the object.

Furthermore, the removal of the supports involves the risk of breaking the object, which is another drawback.

In addition to the above, there is a further drawback represented by the slowing down in the manufacture of the object, as the stimulation of the base material must be carried out also in the areas corresponding to the supports. It is also known that, in the attempt to limit the negative consequences of the suction effect, in a further solution adopted in the known art tanks V are used whose bottom F is covered with a non-stick covering material.

This solution, in fact, favours the detachment of the model from the bottom F thus reducing the risk of breakage of the three-dimensional object.

However, disadvantageously, the use of the non-stick covering on the bottom F of the tank V determines increased wear of the stereolithography machine M, which makes it necessary to perform maintenance more frequently.

Furthermore said drawbacks, due to the suction effect, are enhanced by the fact that in the last few years there is a tendency to use fluid substances with a high degree of viscosity that is due to the fact that they contain ceramic particles.

In fact, as is known, disadvantageously, the higher the degree of viscosity, the higher the suction effect, which consequently leads to an enhancement of all the negative aspects described above.

The present invention intends to overcome all the drawbacks of the known art outlined above.

In particular, it is a first object of the invention to implement a method and to develop a stereolithography machine for manufacturing three-dimensional objects formed by a plurality of superimposed layers, which exclude the risk of air bubbles being present between the solidified layers of the object.

It is another object of the invention to provide a method and a stereolithography machine that make it possible to produce a three- dimensional object in an environment that is thermally insulated from the outside, so as to reduce its heat exchange and thus reduce the thermal gradient between the various layers and/or between the various areas of one same layer of the fluid substance.

Furthermore, it is the object of the invention to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to obtain a faster polymerization process of the fluid substance compared to the techniques of the known art.

Again, it is the object of the invention to provide a method and a stereolithography machine for the production of three-dimensional objects that reduce, if not eliminate, the suction effect that is generated during the production of said three-dimensional objects compared to the stereolithography machines of the known art.

Consequently, it is the object of the invention to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to reduce the number and the size of the supports of the object being made.

It is a further object of the invention to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to use types of tanks that are more rigid and do not require the application of non-stick covering materials, thus reducing the degree of wear of the machine and the need for maintenance operations.

It is another, yet not the least object of the invention to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to use fluid substances with a high degree of viscosity, with no risk of increasing the suction effect.

The above mentioned objects are achieved by a method for the production of three-dimensional objects implemented according to claim 1.

The above mentioned objects are also achieved by a stereolithography machine constructed according to claim five. Further characteristics and details of the invention are described in the dependent claims.

Advantageously, the implementation of the method of the invention makes it possible to reduce the production time of a three-dimensional object compared to the methods of the known art.

Still advantageously, the use of the method and of the stereolithography machine of the invention makes it possible to obtain three-dimensional objects featuring higher quality and more stability over time.

Furthermore, the reduction or elimination of the suction effect advantageously makes it possible to produce bigger three-dimensional objects than those obtainable with stereolithography machines of the known art having the same size.

The said objects and advantages, together with others which will be specified below, are illustrated in the description of a preferred embodiment of the invention which is provided by way of non-limiting example with reference to the attached drawings, wherein:

- Figure 1 shows a schematic view of the first macro type of stereolithography machines belonging to the known art;

- Figure 2 shows a schematic view of the second macro type of stereolithography machines belonging to the known art;

- Figure 3 shows a schematic view of the preferred embodiment of the stereolithography machine of the invention, using the method of the invention;

- Figure 4 shows a schematic view of a second embodiment of the stereolithography machine of the invention, using the method of the invention;

- Figure 5 shows a schematic view of a variant of the first embodiment of the stereolithography machine of the invention shown in Figure 3 and using the method of the invention;

- Figure 6 shows a schematic view of a variant of the second embodiment of the stereolithography machine of the invention shown in Figure 4 and using the method of the invention.

The method of the invention, known as "stereolithography" in technical jargon, is particularly suitable for rapidly prototyping three-dimensional objects O.

As already explained, the method consists in making the three-dimensional object O by superimposing a plurality of layers L of a fluid substance R.

The above mentioned substance R, as explained in detail above, is fluid at ambient temperature but, following suitable stimulation, can alter its molecular structure in such a way as to solidify.

Preferably but not necessarily said fluid substance R is a liquid resin.

It cannot be excluded, however, that said fluid substance can be of any other type, provided that it is able to solidify when exposed to stimulation.

Furthermore, the above mentioned fluid substance R is preferably but not necessarily a fluid photopolymer that solidifies through polymerization when it is exposed to a predefined source of radiations, like for example a laser beam.

Materials of the type described above are well known and largely used in the field of stereolithography, and therefore will not be described in greater detail herein.

It is also evident that, in construction variants of the method of the invention, it is possible to choose a fluid substance that is sensitive to a kind of stimulation different from a laser beam, provided that it is capable of causing the solidification of the same in the stimulated areas.

The method that is the subject of the invention is described with particular reference to the stereolithography machine schematically shown in Figure 3 and indicated as a whole by 1 therein, which is also part of the invention.

However, the method of the invention is suited to be applied also to the different type of stereolithography machine 1 of Figure 4, also an integral part of the invention.

Regarding both stereolithography machines 1 of the invention shown in Figures 3 and 4, they comprise a tank 2 for containing said fluid substance R. Furthermore, both stereolithography machines 1 comprise a modelling head 3 provided with a plate 4, a surface 5 of which, called supporting surface, is suited to support the object O to be made.

In particular, regarding the preferred embodiment of the stereolithography machine 1 of the invention, as shown in Figure 3, the supporting surface 5 faces towards the bottom 21 of the tank 2.

On the contrary, in the alternative embodiment of the stereolithography machine 1 of the invention shown in Figure 4, said supporting surface 5 faces towards the top of the tank 2.

In order to be able to move the head 3 and the plate 4 inside the tank 2 according to a direction of movement substantially orthogonal to the bottom 21 of the same tank 2 and thus progressively obtain the solidification of the various layers L of the fluid substance R, the stereolithography machine 1 of the invention comprises actuator means 6 operatively connected to said head 3.

Furthermore, for both types of stereolithography machine 1 of Figures 3 and 4, the supporting surface 5 is arranged so that it faces an emitter device 7 suited to emit the stimulation that, as already explained, is suited to selectively solidify predefined areas K of each layer L corresponding to the volume of the three- dimensional object O to be obtained.

The emitter device 7 preferably comprises a laser generator 71.

According to the preferred embodiment of the stereolithography machine 1 of the invention of Figure 3, the emitter device 7 is positioned on the underside of the bottom 21 of the tank 2 and, furthermore, the same bottom 21 is made of a transparent material in order to allow the stimulation of the lower layer L of the fluid substance R that is more adjacent to the above mentioned bottom 21. On the contrary, in the embodiment of the machine of the invention 1 of Figure 4, the emitter device 7 is located at the level of the top of the tank 2 to perform the stimulation of the surface layer L of the fluid substance R.

According to the invention, in the stereolithography machine 1 , as shown in Figures 3 and 4, the tank 2 is tight and insulated, meaning that it prevents any exchange of fluids between its inside and the external environment. In particular, the preferred embodiment of the invention comprises a containment chamber 8 made up of walls 81 firmly connected to one another so as to prevent the exchange of fluids between its inside and the external environment.

As shown in Figure 3, said containment chamber 8 contains the tank 2 that in turn contains the fluid substance R, the head 3 with the relevant plate 4, the actuator means 6 for moving the same head 3 and the stimulation emitter device 7.

A first alternative embodiment of the invention may not be provided with said containment chamber 8 and said tight insulation of the tank 2 may be obtained by making the same tank 2 completely closed with walls firmly connected to one another.

It cannot be excluded that in further different embodiments of the stereolithography machine 1 of the invention the actuator means 6 may be positioned outside said containment chamber 8, provided that they are operatively connected to the head 3, in such a way as to maintain the inside of the same containment chamber 8 completely insulated from the external environment.

In further alternative embodiments of the stereolithography machine 1 of the invention also the emitter device 7 may be placed outside the containment chamber 8, as shown in Figure 5 and in Figure 6, provided that it is positioned in proximity to a wall 81 of the same chamber 8 made of a transparent material.

In this way the stimulation, in particular the laser beam, can pass through said wall 81 without any deviations from its angle of incidence, and thus in such a way as to correctly stimulate the layer L of the fluid substance R that is adjacent to it.

Furthermore, in the stereolithography machine 1 of the invention the containment chamber 8 is operatively connected to a vacuum generator unit 9, so as to allow the implementation of the method of the invention.

Finally, in a variant embodiment of the stereolithography machine 1 of the invention there may be also a unit for controlling the temperature inside the tank 2, which would make it possible to adjust humidity inside the same tank 2 by using said temperature control together with the pressure control provided by the vacuum generator 9. Regarding the method of the invention for making three-dimensional objects O, it includes an operation in which a fluid photopolymer R is made flow on a supporting surface exposed to a stimulation source, in such a way as to define a layer L adjacent to the previous layer L. In the case of the implementation of the above mentioned method of the invention by means of the preferred embodiment of the stereolithography machine 1 of Figure 3, this operation is performed by lowering the head 3 and the respective plate 4 towards the bottom 21 of the tank 2, until between the previously solidified layer L and the bottom 21 there is a quantity of the fluid photopolymer R whose thickness is equal to the thickness of the successive layer L to solidify.

According to the method of the invention, the layer L adjacent to the bottom 21 is then selectively subjected to stimulation through the emitter device 7 in the areas K corresponding to the volume of the object O to be made.

Once the predefined areas K of said layer L have solidified, the head 3 and the plate 4 are lifted so as to allow complete levelling of the fluid photopolymer R inside the tank 2.

These operations are repeated in sequence for all the layers L necessary for making the three-dimensional object O.

According to the method of the invention, before starting the execution of and then sequentially repeating said steps regarding the flow and exposure of the fluid photopolymer R for each layer L of the object O to be made, there is a step of reducing the pressure inside said containment chamber 8 with respect to the external atmospheric pressure.

Said pressure reduction is made possible by the vacuum generation means 9 operatively connected to the containment chamber 8.

Preferably but not necessarily, said pressure value is maintained for the period of time from the beginning of said steps regarding the flow and exposure of the fluid photopolymer R until the completion of the three-dimensional object O. Advantageously, the pressure decrease inside the containment chamber 8 makes it possible to reduce, if not to eliminate, the so-called suction effect that takes place in the stereolithography machines of the known art at the moment when the head 3 is lifted together with the plate 4, as widely explained in the description of the known art.

According to the preferred embodiment of the method of the invention, said pressure in the environment where the three-dimensional object O is produced, that is, inside the containment chamber 8, is reduced until reaching absolute vacuum.

However, it cannot be excluded that said pressure may be reduced to a value included between atmospheric pressure and absolute vacuum.

The above clearly shows that the method of the invention and the stereolithography machine of the invention achieve all the set objects.

In particular, the invention achieves the object to implement a method and to develop a stereolithography machine for manufacturing three-dimensional objects formed by a plurality of superimposed layers, which exclude the risk of air bubbles being present between the solidified layers of the object.

The invention also achieves the object to provide a method and a stereolithography machine that make it possible to produce a three- dimensional object in an environment that is thermally insulated from the outside, so as to reduce its heat exchange and thus reduce the thermal gradient between the various layers and/or between the various areas of one same layer of the fluid substance.

Furthermore, the invention also achieves the object to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to obtain a more rapid polymerization process of the fluid substance compared to the techniques of the known art.

Again, the invention achieves the object to provide a method and a stereolithography machine for the production of three-dimensional objects that reduce, if not eliminate, the suction effect that is generated during the production of said three-dimensional objects compared to the stereolithography machines of the known art.

Consequently, the invention also achieves the object to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to reduce the number and the size of the supports of the object being made.

The invention furthermore achieves the object to provide a method and a stereolithography machine for manufacturing three-dimensional objects that make it possible to use types of tank that are more rigid and do not require the application of layers of non-stick covering material, thus reducing the degree of wear of the same machine and the need for maintenance operations.

Finally, the invention also achieves the object to provide a method and a stereolithography machine for the production of three-dimensional objects that make it possible to use fluid substances with a high degree of viscosity, with no risk of increasing the suction effect.

On implementation, the method and the stereolithography machine that are the subjects of the invention may undergo changes that, though not illustrated or described herein, shall nonetheless be covered by the present patent, provided that they come within the scope of the claims that follow.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the protection of each element identified by way of example by such reference signs.

Claims

1) Method for manufacturing three-dimensional objects (O) consisting of a plurality of superimposed layers (L) of a fluid photopolymer (R) capable of solidifying through polymerization following a stimulating action, comprising the operations described below:

- making said fluid photopolymer (R) flow on a supporting surface exposed to said stimulation so as to define a layer (L) adjacent to the previous layer (L);

- selectively exposing said layer (L) to said stimulation in one or more predefined areas (K);

- repeating said step regarding the flow and the exposure for each successive layer (L) of said three-dimensional object (O);

characterized in that it includes an operation intended to reduce pressure in the environment where said three-dimensional object (O) is manufactured compared to the external atmospheric pressure, prior to said operations regarding flow and exposure.

2) Method according to claim 1), characterized in that said pressure reducing operation brings said pressure of said manufacturing environment to a predefined value included between the atmospheric pressure and absolute vacuum.

3) Method according to claim 2), characterized in that said predefined pressure value corresponds to absolute vacuum.

4) Method according to claim 2) or 3), characterized in that said predefined pressure value is maintained for the whole duration of said operations regarding the flow and the exposure of said layers (L).

5) Stereolithography machine (1) for manufacturing three-dimensional objects (O) with a fluid photopolymer (R) suited to solidify through polymerization following a predefined stimulating action, comprising:

- a tank (2) suited to contain said fluid photopolymer (R);

- an emitter device (7) suited to emit said stimulation;

- a modelling head (3) comprising a plate (4) provided with a supporting surface (5) for said three-dimensional object (O) to be manufactured, facing said emitter device (7);

- actuator means (6) suited to move said head (3) inside said tank (2) according to a direction of movement that is substantially orthogonal to the bottom (21) of said tank (2),

characterized in that said tank (2) is tightly insulated from the external environment and operatively connected to a vacuum generation unit (9) suited to provide for reducing the pressure inside said tank (2) compared to the external atmospheric pressure.

6) Stereolithography machine (1) according to claim 5), characterized in that said tank (2) is arranged inside a containment chamber (8) to obtain said tight insulation of at least said tank (2).

7) Stereolithography machine (1) according to claim 5), characterized in that said tank (2) is defined by a plurality of walls firmly connected to one another in such a way as to allow the tight insulation of said tank (2) from the external environment.

8) Stereolithography machine (1) according to any of the claims from 5) to 7), characterized in that also said head (3) and said actuator means (6) are tightly insulated from the external environment.

9) Stereolithography machine (1) according to any of the claims from 5) to 8), characterized in that said emitter device (7) is tightly insulated from the external environment.

10) Stereolithography machine (1) according to any of the claims from 5) to 9), characterized in that said bottom (21) is made of a transparent material and said emitter device (7) is arranged on the underside of said bottom (21) so as to allow the stimulation of the lower layer (L) of said fluid photopolymer (R) placed inside said tank (2).

11) Stereolithography machine (1) according to any of the claims from 5) to 9), characterized in that said emitter device (7) is arranged at the level of the upper part of said tank (2) in order to stimulate the upper surface of said fluid photopolymer (R) placed inside said tank (2).

12) Stereolithography machine (1) according to any of the claims from 5) to 11), characterized in that it comprises a unit for controlling the temperature inside said tank (2) in order to adjust, together with said vacuum generation unit (9), the humidity level inside said tank (2).