Apparatus and method for forming a three-dimensional object

Abstract

Apparatus for forming a three-dimensional object by layer-by-layer additive manufacturing from a polymerizable liquid (3), comprising a tray (7) having first and second ports (25, 26), a source of a fluid (21) comprising a polymerization inhibitor inhibiting the polymerization of the polymerizable liquid (3), a circuit (22) for circulation of the fluid, between the first and second ports, a film (50) placed between the window (10) and the build support (8), the film being permeable to the inhibitor to allow a portion of the inhibitor to pass into the polymerizable liquid, and at least one separator element (70) located between the window (10) and a main surface (F1) of the film (50) and configured to create at least one gap (71) fluidly connecting the first port (25) to the second port (26), for circulation of the fluid (21) within the at least one gap (71).

Description

[0001] Apparatus and method for forming a three-dimensional object

[0002] TECHNICAL FIELD

[0003] The present invention relates to the formation of a three-dimensional object, in particular layer-by-layer additive manufacturing from a polymerizable liquid configured to form a polymerized layer, for example under the effect of irradiation with light radiation.

[0004] The present invention finds, for example, a particularly advantageous application in the additive manufacturing of orthodontic equipment such as gutters and parts of dental prostheses.

[0005] STATE OF THE ART

[0006] Currently, three-dimensional printers, called "3D", are used to manufacture three-dimensional objects. For example, 3D printers of the SLA type (Stereolithography Apparatus in English) are used, which are devices using polymerizable resins. Very often these resins are photo-polymerizable, that is to say they are configured to harden under the action of light, generally in a wavelength range of 360 to 410 nm, to manufacture objects additively layer by layer.

[0007] There are several types of 3D printers, some of which use a bottom-up printing technique. Such printers use a tray containing the photopolymerizable resin, a projector placed under the tray so as to project a pattern corresponding to the cut of the object through the tray and a construction support mounted on a movable arm in vertical translation perpendicular to the tray. In addition, the tray includes a bottom transparent to the projected light and the construction support corresponds to a plate intended to translate upwards, and step by step, to carry with it the freshly polymerized resin which adheres to this support (or to the upper layer for the following translations).For example, European patent application EP0484086 B1 discloses such a type of 3D printer, further using a semi-permeable and transparent film placed on a transparent plate and comprising first and second tubes for injecting a mixture comprising a dissolved inhibitor, such as oxygen, between the film and the plate. Such a printer uses the inhibition properties of oxygen to limit the adhesion effects of the resin being polymerized with the semi-permeable film by saturating the resin with oxygen. But the process is complex and requires a step of horizontal translation of the resin tank to facilitate detachment between the polymerized resin and the film, which slows down the printing process. Also cite US patent application US2019 / 099948 A1, which discloses a method for manufacturing a three-dimensional object.

[0008] SUMMARY

[0009] An object of the invention is to overcome these drawbacks, and more particularly to provide means for manufacturing a three-dimensional object which improve the manufacturing quality.

[0010] Another object is to provide manufacturing means that allow to reduce the manufacturing times of three-dimensional objects.

[0011] Other objects, features and advantages of the present invention will become apparent from the following description and accompanying drawings.

[0012] According to one aspect of the invention, there is provided an apparatus for forming a three-dimensional object by layer-by-layer additive manufacturing from a polymerizable liquid, the polymerizable liquid being configured to form a polymerized material under the effect of irradiation with light radiation, the apparatus comprising:

[0013] - a container configured to contain the polymerizable liquid, the container comprising first and second orifices and a window transparent to light radiation located between the first and second orifices;

[0014] - a building support on which a three-dimensional object is intended to be formed, the building support being movable so as to move a portion of the polymerized material in order to form the three-dimensional object;

[0015] - a source of a fluid comprising a polymerization inhibitor of the polymerizable liquid;

[0016] - a circuit for circulation of the fluid, comprising a first fluid line fluidly connecting the source to the first orifice and a second fluid line connecting the source to the second orifice; and

[0017] - a film located between the window and the construction support, and comprising a main surface intended to be in contact with the polymerizable liquid, the film being permeable to the inhibitor to allow a part of the inhibitor to pass into the polymerizable liquid.

[0018] The apparatus comprises at least one separator element located between the window and the main surface of the film and configured to create at least one gap fluidly connecting the first orifice to the second orifice, for circulation of the fluid within said at least one gap.

[0019] Thus, a simple-to-produce apparatus is provided that facilitates the detachment between the polymerized layer and the film. Such an apparatus saves considerable time for the manufacture of the three-dimensional object. In addition, the spacing makes it easier to inhibit the polymerization of the polymerizable liquid by the inhibitor to limit the adhesion effects of the liquid on the film in order to facilitate the detachment of the polymerized liquid. Such an apparatus provides a means for controlling, in volume, flow rate, etc., the circulation of the fluid comprising the inhibitor.

[0020] According to another aspect, there is provided a method for forming a three-dimensional object by layer-by-layer additive manufacturing from a polymerizable liquid, the polymerizable liquid being configured to form a polymerized material upon irradiation with light radiation, the method comprising providing an apparatus comprising:

[0021] - a container configured to contain the polymerizable liquid, the container comprising first and second orifices and a window transparent to light radiation located between the first and second orifices;

[0022] - a building support on which a three-dimensional object is intended to be formed, the building support being movable so as to move a portion of the polymerized material in order to form the three-dimensional object;

[0023] - a source of a fluid comprising a polymerization inhibitor of the polymerizable liquid;

[0024] - a circuit for circulation of the fluid, comprising a first fluid line fluidly connecting the source to the first orifice and a second fluid line connecting the source to the second orifice; and

[0025] - a film located between the window and the support, and comprising a main surface intended to be in contact with the polymerizable liquid, the film being permeable to the inhibitor to allow part of the inhibitor to pass into the polymerizable liquid.

[0026] The apparatus comprises at least one separator element located between the window and the main surface of the film and configured to create at least one gap fluidly connecting the first orifice to the second orifice and the method comprises circulating the fluid within said at least one gap and irradiating the polymerizable liquid with light radiation.

[0027] According to another aspect, there is provided a computer program product, comprising instructions, which when carried out by at least one processor, cause said at least one processor to control the apparatus as defined above so that the apparatus executes at least the method as defined above.

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] Other advantages and characteristics will emerge more clearly from the following description of embodiments and implementations of the invention given as non-limiting examples and represented in the appended drawings, in which: Figure 1 schematically illustrates a view of an embodiment of an apparatus for forming a three-dimensional object according to the invention; Figures 2 to 5 schematically illustrate different embodiments of a film; Figure 6 schematically illustrates the main steps of a method for forming a three-dimensional object according to the invention; and

[0030] Figure 7 schematically illustrates a view of another embodiment of an apparatus for forming a three-dimensional object. DETAILED DESCRIPTION

[0031] Before commencing a detailed review of embodiments of the invention, optional features which may optionally be used in combination or alternatively are set out below.

[0032] For example, said at least one separating element is a rib extending longitudinally along an axis oriented parallel to the main surface of the film.

[0033] For example, said at least one separating element is a part extending longitudinally along an axis oriented perpendicular to the main surface of the film.

[0034] For example, the film has a secondary surface located opposite the window and said at least one separating element is fixed on the secondary surface of the film.

[0035] For example, at least one separating element is additionally attached to the window.

[0036] For example, the apparatus comprises at least two separating elements delimiting between them said at least one spacing, each separating element being formed within a thickness of the film, the thickness of the film being measured in a direction perpendicular to the main surface of the film.

[0037] For example, the fluid exerts a first pressure in the first fluid line and a second pressure in the second fluid line, the apparatus comprising a circulation device configured to circulate the fluid such that the first and second pressures are less than or equal to a sum of an external pressure exerted on the tank and a pressure exerted by a height of polymerizable liquid contained in the tank.

[0038] For example, the apparatus includes a projector configured to produce light radiation to irradiate the polymerizable liquid and the fluid exerts a first pressure in the first fluid line and a second pressure in the second fluid line, the apparatus including a circulation device configured to circulate the fluid such that the first and second pressures are less than or equal to a sum of an external pressure exerted on the tank and a pressure exerted by a height of polymerizable liquid contained in the tank during irradiation of the polymerizable liquid.

[0039] For example, the circulation device is configured to circulate the fluid such that the first pressure is strictly greater than the second pressure.

[0040] For example, the circulation device is configured to circulate the fluid such that the first and second pressures are less than or equal to the external pressure exerted on the tank.

[0041] For example, the circulation device is configured to circulate the fluid such that the first and second pressures are less than or equal to the external pressure exerted on the tank during irradiation of the polymerizable liquid.

[0042] For example, the circulation device includes an additional fluid line fluidly connected to the source, the additional fluid line including a pump configured to circulate the inhibitor in the fluid. For example, the pump is configured to inject the inhibitor into the fluid at a pressure greater than or equal to the external pressure. Thus, better saturation of the fluid with inhibitor can be achieved.

[0043] For example, the refractive index of the fluid is equal to that of said at least one separating element. For example, the film comprises a first portion fixed to the tank and a second portion free to move relative to the tank.

[0044] For example, the second portion of the film may move relative to the window. Preferably, the second portion of the film may move relative to the window in a direction parallel to a translation axis. More particularly, the translation axis is perpendicular to a build surface of the build support, the build surface being located opposite the window.

[0045] Preferably the second portion of the film can move relative to the window in a direction perpendicular to the main surface of the film.

[0046] For example, the apparatus comprises a separator support placed between the window and the film, the separator support having a first surface fixed to the window and a second surface on which said at least one separator element is located opposite the film. This improves the freedom of movement of the second part of the film relative to the window to promote detachment of the polymerized layer and prevent detachment of the object from the construction surface when the construction support is moved. Such a separator support is easy to manufacture.

[0047] For example, this second part can undergo a displacement, under the effect of traction in a direction parallel to the translation axis (therefore vertical upwards) exerted by the polymerized layer carried by the construction support.

[0048] For example, said at least one separating element is attached to the second surface.

[0049] For example, the separator support and said at least one separator element form a single piece, preferably said at least one separator element comes from the material of the second surface of the separator support. For example, said at least one separator element is formed by machining the separator support, by forming the gaps on the second surface of the separator support, for example by engraving.

[0050] For example, the fluid exerts a first pressure in the first fluid line and a second pressure in the second fluid line, and the circulation includes pressurizing the fluid such that the first and second pressures are less than or equal to a sum of an external pressure exerted on the tank and a pressure exerted by a height of polymerizable liquid contained in the tank.

[0051] For example, circulation involves pressurizing the fluid so that the first pressure is strictly greater than the second pressure.

[0052] For example, the circulation includes pressurizing the fluid such that the first and second pressures are less than or equal to the external pressure exerted on the tray. For example, the method includes, after irradiation, peeling off the polymerized layer from the film, the peeling including moving away from the build support so as to increase a distance between the build support and the window.

[0053] For example, the film comprises a first part fixed to the tray and a second part free to move relative to the tray, and the detachment comprises a displacement of the second part in translation along an axis perpendicular to the main surface of the film.

[0054] For example, the detachment comprises a measurement of a variation in a pressure difference between the first and second pressures and the distance comprises a displacement of the building support relative to the window based on the measured variation.

[0055] In Figures 1 and 6, an apparatus 1 is shown for forming a three-dimensional object 2. In particular, the apparatus 1 is adapted to manufacture the three-dimensional object 2 using a layer-by-layer additive technique from a polymerizable liquid 3. This apparatus 1 is also called a three-dimensional printer, or 3D printer. Layer-by-layer additive manufacturing consists of forming the three-dimensional object 2 one layer 4 after the other in successive steps, each layer 4 extending added to the previous one at each new printing step. More particularly, the polymerizable liquid 3 is configured to form a polymerized layer 4 under the effect of irradiation with light radiation 5. In other words, the polymerizable liquid 3 is configured to form a polymerized material whose parts correspond to the polymerized layers 4. Preferably, the polymerizable liquid 3 is a photopolymerizable resin.The light radiation is produced by a projector 6, for example a DLP type projector (Digital Light Processing, which corresponds to screens using orientable mirrors). The projector 6 can also emit light radiation 5 of the laser type. Preferably, the light radiation 5 corresponds to ultraviolet radiation.

[0056] The apparatus 1 further comprises a tank 7 and a construction support 8. The tank 7 corresponds to a container configured to contain the polymerizable liquid 3. The tank 7 comprises a wall 100 configured to contain the polymerizable liquid 3 and within which a window 10 transparent to the light radiation 5 is formed. The tank 7 further comprises a source 11 of liquid containing a reserve of polymerizable liquid 3. The source 11 is configured to supply the tank 7 with polymerizable liquid 3 in a controlled manner for each step of creating a layer of the three-dimensional object 2. By transparent to the light radiation 5 is meant the fact that the window 10 lets through at least 80% of the light radiation 5 and preferably at least 90% of the light radiation 5, preferably 100% of the light radiation 5.

[0057] The construction support 8 provides a support on which the three-dimensional object 2 is intended to be formed. The construction support 8 has a general shape of a plate. In particular, the construction support 8 is provided with a construction surface 12 located opposite the window 10. Furthermore, the construction support 8 is movable so as to move a portion of the polymerized material 4 in order to form the three-dimensional object 2. For example, the apparatus 1 comprises an arm 9 mechanically coupled to the construction support 8. The arm 9 is mounted movably on a support 40. More particularly, the arm 9 is movable in translation along a translation axis A perpendicular to the construction surface 12 of the construction support 8. The mobility of the arm 9 makes it possible to move the construction support 8, to move the polymerized layer 4 in order to form the three-dimensional object 2.

[0058] Printing a layer of the three-dimensional object 2 consists of projecting a pattern corresponding to the section of the object 2, by means of the projector 6, through the transparent window 10. Thus, a liquid zone 13 polymerizes 3 under the effect of the light radiation 5 to form the polymerized layer 4. In other words, the liquid zone 13 hardens under the effect of the light radiation 5. When the zone 13 hardens, it adheres either to the construction support 8 for the first layer of the object 2, or to a previously formed layer corresponding to a polymerized layer of the object 2.

[0059] The apparatus 1 further comprises a source 20 of a fluid 21 comprising a polymerization inhibitor of the polymerizable liquid 3, and a circuit 22 for circulation of the fluid 21. Furthermore, the circuit 22 comprises a first fluid line 23 and a second fluid line 24. Furthermore, the tank 7 comprises first and second orifices 25, 26. The window 10 is located between the first and second orifices 25, 26. For example, the first and second orifices 25, 26 are formed within the wall 100 of the tank 7. The first fluid line 23 fluidically connects the source 20 to the first orifice 25. Furthermore, the second fluid line 24 connects the source 20 to the second orifice 26. Generally, the fluid 21 exerts a first pressure P1 within the first fluid line 23 and a second pressure P2 within the second fluid line 24.

[0060] Preferably, the fluid 21 is a liquid and the inhibitor is oxygen.

[0061] Furthermore, the apparatus 1 comprises a film 50 located between the window 10 and the construction support 8. The film 50 is placed on the wall 100 of the tank 7. In particular, the film 50 is placed on the window 10. In particular, the film 50 comprises a main surface F1 intended to be in contact with the polymerizable liquid 3. The film 50 is permeable to the inhibitor to allow a portion of the inhibitor to pass into the polymerizable liquid 3. That is to say, the inhibitor can pass through the main surface F1 to the polymerizable liquid 3. A problem for printing the object 2 consists in the fact that the polymerized layer 4 must adhere more to the construction support 8 than to the film 50, otherwise it cannot be moved upwards to make room for the following layers.The adhesion between the film 50 and the polymerizable liquid 3 is due to the microstructure of the materials, the chemical affinity between the materials and a suction effect between the polymerizable liquid 3 and the film 50 when the liquid 3 polymerizes. Thus, to limit the suction effect, the permeable film 50 allows the inhibitor to pass through the film 50 into the polymerizable liquid 3. The inhibitor inhibits the polymerization reaction. For example, the inhibitor comprises oxygen. In particular, oxygen inhibits the polymerization reaction because it is an absorber of free radicals which are elements allowing the polymerization reaction. The inhibition allows the creation of a liquid interface of the unpolymerized liquid 3 which allows a further reduction of the suction effects. The circuit 22 is configured to circulate the liquid 21 comprising the inhibitor between the main surface F1 of the film 50 and the transparent window 10.

[0062] More particularly, the apparatus 1 comprises at least one separating element 70 located between the window 10 and the main surface F1 of the film 50. A separating element 70 is configured to create at least one spacing 71 fluidly connecting the first orifice 25 to the second orifice 26, for circulation of the fluid 21 within the spacing 71.

[0063] Such a separating element 70 makes it possible to keep the main surface F1 of the film at a distance from the window 10 while creating a spacing 71 for circulating the fluid 21 between the main surface F1 and the window 10. It is thus possible to guarantee a spacing 71 for the circulation of the fluid 21 during the manufacture of the object 2. This makes it easier to control the volume and the speed of movement of the fluid 21 during the manufacture of the object 2.

[0064] In Figures 2 to 5, different embodiments of a separator element 70 are shown. Generally, the film 50 extends along a secondary axis B perpendicular to the translation axis A. Furthermore, the fluid 21 circulates within the circuit 22 according to circulation directions referenced S1, S2, S3. When the fluid 21 circulates between the window 10 and the main surface F1 of the film 50, the fluid 21 circulates in the direction S2, that is to say in the secondary axis B. In general, the separating elements 70 can be formed on the film 50 or on the window 10. In particular, the separating elements 70 can be fixed on a secondary surface F2, opposite the main surface F1, located opposite the window 10. The separating elements 70 can be fixed on a surface of the window 10 located opposite the polymerizable liquid 3. Preferably, the separating elements 70 are formed on the secondary surface F2 of the film 50.For example, the separating elements can be made of silicone. For example, the separating elements can be printed on the film 50 by stamping, that is to say by pressing a die onto the film 50. Alternatively, the separating elements 70 can be made by molding onto the film 50. According to yet another variant, the separating elements 70 can be made by machining or by molding onto the window 10. According to another example, the separating elements 70 are formed on the secondary surface F2 of the film 50 or on the window 10 by molding from liquid silicone. The silicone material can be molded directly to allow optical coupling with the window or the film 50. Advantageously, the refractive index of the fluid 21 is equal to that of the separating elements 70. Thus, the pattern projected by the projector 6 is not distorted. Sufficient contrast is also guaranteed to produce the object 2.The accuracy and / or surface condition of the printed object is little affected. To obtain an equal refractive index for the separating elements 70 and the fluid 21, several liquids miscible with each other and having different refractive indices can be mixed. For example, monopropylene glycol and pure water can be mixed. In Figures 2 and 3, a separating element 70 is a part extending longitudinally along an axis A oriented perpendicular to the main surface F1 of the film 50. Preferably, the apparatus 1 comprises several separating elements 70. A separating element 70 can have a cylindrical or conical shape. The cylindrical shape is preferred because it facilitates the flow of the fluid 21. A separating element 70 has a height H which can be between 50 and 300 micrometers. Thus, the separating elements 70 do not prevent the circulation of the fluid 21.The height H is measured along an axis perpendicular to the main surface F1. For example, the separating elements 70 may have a width L1 equal to 1 mm. A distance L2 between the separating elements may be between 0.1 and 2 mm. Thus, the separating elements 70 allow circulation of the fluid 21 while preventing bending of the film 50 between the separating elements 70. For example, the centers of the separating elements 70 may be separated by a distance L3 of between 1.1 and 1.2 mm. The width L1 and the distances L2, L3 are measured along an axis parallel to the secondary axis B.

[0065] In Figure 4, the apparatus 1 comprises at least two separating elements 70 delimiting between them a spacing 71. Each separating element 70 is formed within a thickness Ef of the film 50. The thickness Ef of the film 50 is measured in a direction perpendicular to the main surface F1 of the film 50. For example, the separating elements 70 are formed in a thickness Ef of the film 50. In other words, the film 50 comprises channels passing through 71 from one edge to the other of the film 50 formed within the thickness Ef of the film 50.

[0066] In Figure 5, a separating element 70 is a rib extending longitudinally along an axis oriented parallel to the main surface F1 of the film 50. In other words, the separating elements 70 form lips projecting from the secondary surface F2 and extend along the secondary axis B. The ribs delimit, between them, channels 71 for the circulation of the fluid 21.

[0067] Furthermore, the apparatus 1 may comprise a circulation device 30 configured to circulate the fluid 21 within the space 71. The circulation device 30 comprises a main pump 81, located for example, in the first fluid line 23 or the second fluid line 24, to circulate the fluid 21 in the closed circuit 22. In this case, the source 20 of fluid 21 comprises an opening to the outside in order to mix the fluid 21 with, for example, air, to inject the inhibitor, such as for example oxygen, into the fluid 21. Advantageously, the device 30 may comprise a secondary pump 80, optional, fluidically connected to the source 20 of the fluid 21, by an additional fluid line 91. The secondary pump 80 is configured to suck in the reaction inhibitor (for example air containing oxygen) 90 to inject it into the fluid 21 in order to circulate it in the closed circuit 22.A pressure P3 is exerted by the fluid 21 within the source 20. The circulation device 30 can be configured so that the first and second pressures P1, P2 are less than or equal to a sum of an external pressure PO exerted on the tank 7 and a pressure exerted by a height of polymerizable liquid 3 contained in the tank 7. Thus, detachment of the film 50 relative to the window 10 is avoided. Detachment of the film 50 is understood to mean the fact that the film 50 is no longer in contact with the window 10.

[0068] Preferably, the film 50 comprises a first part fixed to the tray 7 and a second part free to move relative to the tray 7. That is to say, the film 50 can be partly fixed to the tray 7. For example, the apparatus 1 comprises fixing means configured to keep the film 50 partly in contact with the tray 7. In other words, the fixing means make it possible to keep the first part of the film 50 in contact with the tray 7, while allowing a movement of the second part of the film 50 relative to the window 10. The movement of the second part of the film 50 corresponds to a translational movement along the translation axis A. For example, as illustrated in FIG. 3, the fixing means can comprise zones 60, 61 present on separator elements 70 fixed to the film 50. The zones 60, 61 are intended to be fixed, for example by gluing, on the window 10.Preferably, the fixing means are configured to fix a portion of the film 50 to the wall 100 of the tank 7. Thus, the fixing means allow a displacement of the second portion of the film 50 along the translation axis A relative to the window 10 without detachment of the film 50 relative to the window 10. Thus, a certain mobility of the second portion of the film 50 is obtained relative to the window 10 to facilitate the detachment of the polymerized layer 4 relative to the film 50, that is to say a detachment of the polymerized layer 4 relative to the main surface F1 of the film 50. By detachment of the polymerized layer 4 is meant a displacement of the polymerized layer 4 relative to the film 50 so that the polymerized layer 4 is no longer in contact with the film 50.

[0069] The pressure P3 within the source 20 of the fluid 21 may be greater than or equal to the external pressure PO. When the pressure P3 is strictly greater than the external pressure PO, it is possible to obtain better saturation of the fluid 21 with inhibitor and improve the manufacture of the object 2. The secondary pump 80 makes it possible to regulate the pressure difference between the pressure P3 and the external pressure PO. The secondary pump 80 advantageously allows the renewal of the inhibitor (for example oxygen) in the fluid 21 by circulating it (pure or in the form of a mixture, for example air in the case of oxygen) in the fluid 21.

[0070] Advantageously, the circulation device 30 is configured to circulate the fluid 21 so that the first pressure P1 is strictly greater than the second pressure P2.

[0071] Advantageously, the circulation device 30 is configured to circulate the fluid 21 so that the first and second pressures P1, P2 are less than or equal to the external pressure PO exerted on the tank 7. For example, the circulation device 30 is configured to regulate the pressures P1 to P3, so that the first pressure P1 is equal to -10 kPa, the second pressure P2 is equal to -15 kPa and P3 is equal to +10 kPa.

[0072] For example, the circulation device 30 is configured to circulate the fluid 21 at a circulation speed which may be between 10 and 100 mL / min. The apparatus 1 may further comprise pressure sensors 95, 96 configured to measure the first and second pressures P1, P2 respectively.

[0073] The circulation device 30 can regulate the pressures P1 and P2 using the pressure sensors 95, 96. This can make it possible to determine when a layer 4 is peeling off, since this causes a further drop in the pressures P1 and P2. It is also possible to use the measurements of the pressures P1, P2 to determine when the layer 4 is completely peeled off, i.e. separated from the film 50 so that the polymerized layer 4 is no longer in contact with the film 50. This can minimize the rise heights of the construction support 8 during the peeling phases and thus allow faster and safer printing. It is also possible to control the pressures P1 and P2. For example, by pumping, using the main pump 81, more or less strongly, or not at all, or even by pumping in the opposite direction, to allow a movement of the film 50 relative to the window 10.The circulation device 30 could also move the film 50 in translation along the translation axis A, in the case where P1 and P2 exceed the sum of the external pressure PO and the pressure exerted by the height of polymerizable fluid 3 contained in the tank 7. This could facilitate the detachment of the layer 4 with the film 50.

[0074] Furthermore, the circulation device 30 is configured to regulate the first and second pressures P1, P2 to variable values. By way of example, the arrows referenced S1, S2, S3 represent a direction of circulation of the fluid 21.

[0075] Furthermore, during irradiation of the polymerizable liquid 3 by the light radiation 5, the circulation device 30 is configured to regulate the first and second pressures P1, P2 to values ​​less than or equal to the external pressure PO exerted on the tank 7. The external pressure PO corresponds to the atmospheric pressure exerted on the polymerizable liquid 3. The spacing 71 promotes the circulation of the fluid 21 along the film 50 to promote the diffusion of the inhibitor within the polymerizable liquid 3.

[0076] In Figure 6, the main steps of a method for forming the three-dimensional object 2 are shown. The method comprises providing the apparatus 1, as defined above. The method further comprises irradiating the polymerizable liquid 3 with the light radiation 5. The irradiation may comprise regulating the first and second pressures P1, P2 so that the first and second pressures P1, P2 are less than or equal to a sum of the external pressure PO exerted on the tank 7 and a pressure exerted by a height of polymerizable liquid 3 contained in the tank 7.

[0077] Preferably, the film 50 is partly fixed to the tank 7. For example, the first part of the film 50 is fixed to the wall 100 of the tank 7. Advantageously, the second part of the film 50 extends along the window 10. The second part of the film 50 can partially or completely cover the main surface of the window 10 located opposite the polymerizable liquid 3.

[0078] During irradiation, the film 50 is stationary relative to the tank 7. Furthermore, it is possible to measure, using the sensors 95, 96, the pressure difference between the first and second pressures P1, P2. During irradiation, the pressure difference has an initial value, because the film 50 is stationary. In order to facilitate the detachment between the film 50 and the polymerized layer 4, the method may comprise, after irradiation, a detachment of the polymerized layer 4 relative to the film 50. The detachment of the polymerized layer 4 comprises a moving away from the construction support 8, in order to move the polymerized layer 4 away by a certain distance to detach the polymerized layer 4 from the film 50. Then, the method comprises a moving closer to the construction support 8 in order to replace the support 8 for the production of a following layer of the object 2.The moving away of the construction support 8 comprises an increase in a distance between the construction support 8 and the window 10. The moving away comprises an initial displacement of the construction support 8 from an initial distance to a maximum distance Dmax. Preferably, the maximum distance Dmax is greater than or equal to a thickness Ec of the polymerized layer 4. The thickness Ec of the polymerized layer is measured along the translation axis A. The maximum distance Dmax is for example equal to 0.5 mm, or for example equal to 5 mm.

[0079] For example, the initial movement is carried out simultaneously with regulation of the first and second pressures P1, P2 to constant values.

[0080] Advantageously, the detachment comprises a displacement of the second part of the film 50 in translation along an axis perpendicular to the main surface F1 of the film 50. During the detachment of the polymerized layer 4, the film 50 is kept partly in contact with the tank 7, while the other part (i.e. the second part free to move) can be displaced relative to the tank 7. In particular, the second part can be displaced in translation along the translation axis A. The displacement of the second part of the film 50 is due to the adhesion of the polymerized layer 4 to the main surface F1 of the film 50, by suction effect. The displacement of the second part of the film 50 also causes a depression in the spacing 71. That is to say a variation in the pressure difference between the first and second pressures P1, P2. The displacement of the second part of the film 50 makes it easier to detach the polymerized layer 4.This movement makes it possible to prevent the object 2 from detaching from the construction support 8. This movement also makes it possible to prevent the first polymerized layers of the object 2 from detaching with the last polymerized layer 4 in contact with the film 50. Indeed, the detachment of the first polymerized layers could occur if the last polymerized layer 4 remained adhered to the film 50. Thus, when the film 50 is partly fixed to the tray 7, the second part of the film 50 can be free to move and can be moved in translation with the last polymerized layer 4. The fixing of the first part of the film 50 also allows the second part of the film 50 to return to the initial position, after the detachment of the last polymerized layer 4, for a subsequent print.

[0081] After the polymerized layer 4 has been detached from the film 50, the method comprises bringing the construction support 8 closer together so as to bring the construction support 8 to a minimum distance Dmin, in order to manufacture the next polymerization layer 4, the bringing closer together comprising an additional movement of the construction support 8 from the maximum distance Dmax to the minimum distance Dmin. The minimum distance Dmin is equal to the sum of the initial distance Dinit and the thickness of a polymerized layer 4. The regulation of the first and second pressures P1, P2 can be carried out so that the first pressure P1 is strictly greater than the second pressure P2. Thus, a constant flow of the fluid 20 can be maintained between the film 50 and the window 10.

[0082] Furthermore, the detachment may comprise a measurement, using the pressure sensors 95, 96, of the variation in the pressure difference between the first and second pressures P1, P2. Thus, when the construction support 8 is moved away, the method may comprise a movement of the construction support 8 relative to the window 10 as a function of the measured variation. For example, when a pressure variation is detected, relative to the initial value, it is determined that the detachment of the polymerized layer has begun. It is therefore possible to continue to move the construction support 8. Advantageously, the speed of movement of the construction support can be controlled. When the pressure difference returns to its initial value, the second part of the film 50 has returned to its initial position, and it is determined that the detachment of the polymerized layer is complete.

[0083] In Figure 7, another embodiment of an apparatus 1 for forming a three-dimensional object 2 is shown. According to this other embodiment, the film 50 comprises a first part 200 fixed to the tank 7 and a second part 201 free to move relative to the tank 7. For example, the apparatus 1 comprises fixing means 202 configured to keep the film 50 partly in contact with the tank 7. In other words, the fixing means 202 make it possible to keep the first part 200 of the film 50 in contact with the tank 7, while allowing a displacement, in translation along the translation axis A, of the second part 201 of the film 50 relative to the window 10. For example, this second part 201 can be deformed to undergo a displacement, under the effect of a vertical upward traction of the polymerized layer 4 which drives by suction this second part 201 of the film 50.For example, as illustrated in FIG. 7, the fixing means 202 comprise a housing formed within the wall 100 and configured to receive the first part 200 of the film 50. For example, the first part 200 may be glued to the wall 100 within the housing. The film 50 may have a parallelepiped shape. Furthermore, the apparatus 1 comprises a support 203 of at least one separator element 70, denoted separator support 203. Generally, the separator support 203 extends along a tertiary axis C perpendicular to the translation axis A. The separator support 203 is placed between the window 10 and the film 50. In particular, the separator support 203 is placed on the window 10.More particularly, the separator support 203 comprises a first surface G1 intended to be in contact with the window 10, and a second surface G2, opposite the first surface G1, the second surface G2 being located opposite the film 50, and more particularly opposite the secondary face F2 of the film 50. For example, the separator support 203 can be fixed, for example by gluing, on the window 10. The separator support 203 can be permeable to the fluid 21 comprising the inhibitor. For example, the separator support 203 can be impermeable to the fluid and permeable to the inhibitor. According to another example, the separator support 203 is impermeable to the fluid 21 and to the inhibitor. For example, the separator support 203 can be made from silicone. The separator support 203 is configured to support the separator elements 70.More particularly, the separator support 203 is configured to hold the separator elements 70 between the window 10 and the film 50, and preferably between the second surface G2 of the separator support 203 and the secondary surface F2 of the film 50. In other words, the separator support 203 is configured to maintain the spacings 71 between the second surface G2 of the separator support 203 and the secondary surface F2 of the film 50. Thus, the spacings 71 between the separator elements 70 allow the fluid 21 to pass towards the film 50, and in particular towards the secondary surface F2 of the film 50. Thus, a portion of the inhibitor can pass through the secondary and main surfaces F2, F1 of the film 50 to reach the polymerizable liquid 3. That is to say, the fluid 21 comprising the inhibitor can circulate within the spacings 71 between the second surface G2 of the separator support 203 and the secondary surface F2 of the film 50. 203 and the secondary surface F2 of film 50.For example, the separator support is placed between the window 10 and the second part 201 of the film 50. Thus, the separator elements 70 are located opposite the second part 201 of the film 50. In particular, at the level of the first orifice 25, the fluid 21 passes within the spaces 71, in the direction of the film 50, in the direction referenced S2', and in the direction of the second orifice 26, in the direction referenced S2. The circuit 22 is configured to circulate the fluid 21 comprising the inhibitor between the second surface G2 of the separator support 203 and the secondary surface F2 of the film 50. Furthermore, when the fluid 21 comprising the inhibitor is found within the spaces 71, the inhibitor can pass through the secondary and main surfaces F2, F1 of the film to reach the polymerizable liquid 3. Furthermore, the fluid 21 circulates within the circuit 22 according to the four circulation directions referenced S1, S2, S2' S3.The second direction S2 corresponds to the circulation of the fluid 21 within the spaces 71 between the separator elements 70. The third direction S2' corresponds to the circulation of the fluid 21 towards the film 50. According to this other embodiment, the separator elements 70 are formed on the separator support 203. In particular, the separator elements 70 can be fixed on the second surface G2 of the separator support 203. Preferably, the separator elements 70 are formed on the second surface G2 of the separator support 203. For example, the separator elements 70 can be made of silicone. For example, the separator elements 70 can be printed on the separator support 203 by stamping, that is to say by pressing a die onto the separator support 203. Alternatively, the separator elements 70 can be made by molding onto the separator support 203.According to yet another variant, the separating elements 70 can be produced by machining on the separator support 203. According to another example, the separating elements 70 are formed on the second surface G2 of the separator support 203 by molding from liquid silicone. The silicone material can be molded directly to allow optical coupling with the separator support 203. Advantageously, the refractive index of the fluid 21 is equal to that of the separating elements 70 and the separator support 203. Thus, the pattern projected by the projector 6 is not deformed. Sufficient contrast is also guaranteed to produce the object 2. The precision and / or surface condition of the printed object is hardly affected. To obtain an equal refractive index for the separating elements 70, the separator support 203 and the fluid 21, several liquids miscible with each other and having different refractive indices can be mixed.For example, you can mix monopropylene glycol and pure water.

[0084] Thus, in this other embodiment, the second part 201 of the film 50 is free to move relative to the separator support 203, and more particularly relative to the separator elements 70. That is to say that the second part 201 of the film 50 is not fixed to the separator elements. Thus, when the first and second pressures P1, P2 are less than or equal to the sum of the external pressure exerted on the tank 7 and the pressure exerted by a height of polymerizable liquid contained in the tank 7, the secondary surface F2 of the second part 201 of the film 50 is in contact with the separating elements 70. In this case, the film 50 is prevented from detaching from the separating elements 70. Furthermore, the fixing means 202 allow the second part 201 of the film 50 to move along the translation axis A relative to the separating elements 70 without the film 50 detaching from the tank 7.Thus, a certain mobility of the second part of the film 50 is obtained relative to the separating elements 70 to facilitate the detachment of the polymerized layer 4 relative to the film 50, that is to say the detachment of the polymerized layer 4 relative to the main surface F1 of the film 50. To facilitate the detachment of the polymerized layer 4 relative to the film 50, the first and second pressures P1, P2 may be strictly greater than the sum of the external pressure exerted on the tank 7 and the pressure exerted by a height of polymerizable liquid contained in the tank 7. In this case, the secondary surface F2 of the second part 201 of the film 50 moves away from the separating elements 70, as illustrated in FIG. 7. In this case, the second part 201 of the film 50 is no longer in contact with the separating elements 70. According to another embodiment, the separating elements 70 and the window 10 form a single piece.Preferably the separating elements 70 come from the material of the window 10, for example by machining by forming the spaces 71 on the surface of the window, for example by engraving.

[0085] The process just described allows for precise control of the manufacturing steps of object 2. This reduces manufacturing times. Manufacturing precision is also improved by limiting printing defects.

[0086] Advantageously, the apparatus 1 comprises an electronic control unit, not shown for the sake of simplification, configured to control the movements of the arm 9, the supply of the tank 7 with polymerizable liquid 3 and the main and secondary pumps 81, 80. The electronic control unit may comprise a computer program comprising instructions for controlling the arm 9, in particular a stepper motor which drives the arm 9 in translation along the translation axis A, and the supply of the tank 7. The electronic control unit comprises a processor, or a microprocessor, for executing the instructions of the program. The electronic control unit also comprises means for controlling the stepper motor and the supply of the tank 7 in response to the execution of the instructions of the program.

[0087] The invention is not limited to the embodiments and implementations previously described. The invention as described allows for rapid 3D printing that is easy to implement.

Claims

Claims 1. Apparatus for forming a three-dimensional object by layer-by-layer additive manufacturing from a polymerizable liquid (3), the polymerizable liquid (3) being configured to form a polymerized material under the effect of irradiation with light radiation (5), the apparatus comprising: - a tank (7) configured to contain the polymerizable liquid (3), the tank (7) comprising first and second orifices (25, 26) and a window (10) transparent to light radiation (5) located between the first and second orifices (25, 26); - a construction support (8) on which a three-dimensional object (2) is intended to be formed, the construction support (8) being movable so as to move a portion of the polymerized material (4) in order to form the three-dimensional object (2); - a source (20) of a fluid (21) comprising a polymerization inhibitor of the polymerizable liquid (3); - a circuit (22) for circulation of the fluid (21), comprising a first fluid line (23) fluidly connecting the source (20) to the first orifice (25) and a second fluid line (24) connecting the source (20) to the second orifice (26); and - a film (50) located between the window (10) and the construction support (8), and comprising a main surface (F1) intended to be in contact with the polymerizable liquid (3), the film (50) being permeable to the inhibitor to allow a part of the inhibitor to pass into the polymerizable liquid (3); and - at least one separating element (70) located between the window (10) and the main surface (F1) of the film (50) and configured to create at least one gap (71) fluidly connecting the first orifice (25) to the second orifice (26), for circulation of the fluid (21) within said at least one gap (71); characterized in that the film (50) comprises a first part fixed to the tank (7) and a second part free to move relative to the tank (7) so that the second part of the film (50) can move relative to the window (10).

2. Apparatus according to the preceding claim, wherein said at least one separating element (70) is a rib extending longitudinally along an axis oriented parallel to the main surface (F1) of the film (50).

3. Apparatus according to claim 1, wherein said at least one separating element (70) is a part extending longitudinally along an axis oriented perpendicular to the main surface (F1) of the film (50).

4. Apparatus according to any one of the preceding claims, wherein the film (50) has a secondary surface (F2) located opposite the window (10) and said at least one separating element (70) is fixed on the secondary surface (F2) of the film (50).

5. Apparatus according to the preceding claim, wherein at least one separating element (70) is further fixed to the window (10).

6. Apparatus according to claim 1, comprising at least two separating elements (70) delimiting between them said at least one spacing (71), each separating element (70) being formed within a thickness of the film (50), the thickness of the film (50) being measured in a direction perpendicular to the main surface (F1) of the film (50).

7. Apparatus according to any one of the preceding claims, comprising a projector (6) configured to produce light radiation for irradiating the polymerizable liquid (3), and wherein the fluid (21) exerts a first pressure (P1) in the first fluid line (23) and a second pressure (P2) in the second fluid line (24), the apparatus comprising a circulation device (30) configured to circulate the fluid (21) such that the first and second pressures (P1, P2) are less than or equal to a sum of an external pressure exerted on the tank (7) and a pressure exerted by a height of polymerizable liquid (3) contained in the tank (7) during the irradiation of the polymerizable liquid (3).

8. Apparatus according to the preceding claim, wherein the circulation device (30) is configured to circulate the fluid (21) so that the first pressure is strictly greater than the second pressure.

9. Apparatus according to any one of claims 7 and 8, wherein the circulation device (30) is configured to circulate the fluid (21) so that the first and second pressures (P1, P2) are less than or equal to the external pressure exerted on the tank (7) during the irradiation of the polymerizable liquid (3).

10. Apparatus according to any one of claims 7 to 9, wherein the circulation device (30) comprises an additional fluid line (91) fluidically connected to the source (20), the additional fluid line (91) comprising a pump (80) configured to circulate the inhibitor in the fluid (21).

11. Apparatus according to claim 10, wherein the pump (80) is configured to inject the inhibitor into the fluid (21) under a pressure greater than or equal to the external pressure.

12. Apparatus according to any one of the preceding claims, wherein the refractive index of the fluid is equal to that of said at least one separating element (70).

13. Apparatus according to any one of the preceding claims, comprising a separator support (203) placed between the window (10) and the film (50), the separator support (203) having a first surface (G1) fixed to the window (10) and a second surface (G2) on which said at least one separator element (70) is located opposite the film (50).

14. Apparatus according to the preceding claim, wherein said at least one separating element (70) is attached to the second surface (G2).

15. Apparatus according to claim 13, wherein the separator support (203) and said at least one separator element (70) form a single piece, preferably said at least one separator element (70) comes from the material of the second surface (G2) of the separator support (203).

16. Method for forming a three-dimensional object by layer-by-layer additive manufacturing from a polymerizable liquid (3), the polymerizable liquid (3) being configured to form a polymerized material (4) under the effect of irradiation with light radiation (5), the method comprising providing an apparatus comprising: - a tank (7) configured to contain the polymerizable liquid (3), the tank (7) comprising first and second orifices (25, 26) and a window (10) transparent to light radiation (5) located between the first and second orifices (25, 26); - a construction support (8) on which a three-dimensional object (2) is intended to be formed, the construction support (8) being movable so as to move a portion of the polymerized material (4) in order to form the three-dimensional object (2); - a source (20) of a fluid (21) comprising a polymerization inhibitor of the polymerizable liquid (3); - a circuit (22) for circulation of the fluid (21), comprising a first fluid line (23) fluidly connecting the source (20) to the first orifice (25) and a second fluid line (24) connecting the source (20) to the second orifice (26); and - a film (50) located between the window (10) and the support (8), and comprising a main surface (F1) intended to be in contact with the polymerizable liquid (3), the film (50) being permeable to the inhibitor to allow part of the inhibitor to pass into the polymerizable liquid (3); and - the apparatus comprises at least one separating element (70) located between the window (10) and the main surface (F1) of the film (50) and configured to create at least one spacing (71) fluidically connecting the first orifice (25) to the second orifice (26), characterized in that the film (50) comprises a first part fixed to the tank (7) and a second part free to move relative to the tank (7) so that the second part of the film (50) can move relative to the window (10), and in that the method comprises a circulation of the fluid (21) within said at least one spacing (71) and an irradiation of the polymerizable liquid (3) by the light radiation (5).

17. Method according to the preceding claim, in which the fluid (21) exerts a first pressure (P1) in the first fluid line (23) and a second pressure (P2) in the second fluid line (24), and the circulation comprises pressurizing the fluid (21) so that the first and second pressures (P1, P2) are less than or equal to a sum of an external pressure exerted on the tank (7) and a pressure exerted by a height of polymerizable liquid (3) contained in the tank (7), during the irradiation of the polymerizable liquid (3) by the light radiation.

18. Method according to claim 17, in which the circulation comprises pressurizing the fluid (21) so that the first pressure is strictly greater than the second pressure.

19. A method according to any one of claims 17 and 18, wherein the circulation comprises pressurizing the fluid (21) so that the first and second pressures (P1, P2) are less than or equal to the external pressure exerted on the tank (7), during the irradiation of the polymerizable liquid (3) by the light radiation.

20. A method according to any one of claims 17 to 19, comprising, after irradiation, detaching the polymerized layer (4) from the film (50), the detaching comprising moving away from the construction support (8) so as to increase a distance between the construction support (8) and the window (10).

21. Method according to the preceding claim, in which the detachment comprises a displacement of the second part in translation along an axis perpendicular to the main surface (F1) of the film (50).

22. Method according to the preceding claim, the apparatus comprising a separator support (203) placed between the window (10) and the film (50), the separator support (203) having a first surface (G1) fixed to the window (10) and a second surface (G2) on which said at least one separator element (70) is located opposite the film (50).

23. Method according to any one of claims 17 to 22, in which the detachment comprises a measurement of a variation of a pressure difference between the first and second pressures (P1, P2) and the distancing comprises a displacement of the construction support (8) relative to the window (10) as a function of the measured variation.

24. Computer program product, comprising instructions, which when carried out by at least one processor, cause said at least one processor to control the apparatus according to any one of claims 1 to 15 so that the apparatus executes at least the method according to any one of claims 16 to 23.

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