Apparatus for 3D printing of bottom-up photo-curing type, with independent elastic membrane system and tilting reference and relative methods of use

Abstract

The present invention concerns an apparatus for 3D printing of bottom-up photo-curing type, comprising a light source (26) above which a tank (10) containing a photo-curing liquid material (24) is placed inside which it is immersed an extraction plate (25), which is equipped with moving means with alternating rectilinear motion, along a direction perpendicular to the bottom of said tank (10) from a position at a distance from the bottom of said tank (10) equal to the thickness of a layer obtainable by photo-curing of said photo-curing liquid material (24), the bottom (14) of said tank (10) being constituted by an elastic membrane (23) transparent to the radiation of said light source (26), said tank (10) being positioned in correspondence with a hole (13) of a support plate (12), said hole being provided with a rigid support (11), transparent to the radiation of said light source (26), wherein said rigid support (11) is provided with means for displacing with respect to said hole (13), from a position in which said rigid support (11) occupies said hole (13), and is in contact with elastic membrane (23), to a position in which said rigid support (11) deviates from said hole (13) and from said elastic membrane (23), characterised in that between said elastic membrane (23) and said rigid support (11) means are placed apt to increase adherence between said elastic membrane (23) and said rigid support (11). The invention additionally concerns a method of use of said apparatus for 3D printing.

Claims

1. Apparatus for 3D printing of bottom-up photo-curing type, comprising a light source (26) above which a tank (10) containing a photo-curing liquid material (24) is placed (24) inside which it is immersed an extraction plate (25), which is configured for alternating rectilinear motion, along a direction perpendicular to the bottom of said tank (10) from a position at a distance from the bottom of said tank (10) equal to the thickness of a layer (27) obtainable by photo-curing of said photo-curing liquid material (24), the bottom (14) of said tank (10) being constituted by an elastic membrane (23) transparent to the radiation of said light source (26), said tank (10) being positioned in correspondence with a hole (13) of a support plate (12), said hole being provided with a rigid support (11), transparent to the radiation of said light source (26), wherein said rigid support (11) is configured for displacing with respect to said hole (13), from a position in which said rigid support (11) occupies said hole (13), and is in contact with elastic membrane (23), to a position in which said rigid support (11) deviates from said hole (13) and from said elastic membrane (23), wherein an adhesive component comprising a layer of an adhesive is applied between said elastic membrane (23) and said rigid support (11) and configured to control a reversible movement of said elastic membrane (23) with respect to said tank (10) in response to said displacing of said rigid support (11), wherein the elastic membrane (23) being at least partly detachable from the rigid support (11), and the adhesive component being configured to control detachment of the elastic membrane (23) from the rigid support (11) to reduce mechanical stress the elastic membrane (23) is subjected to.

2. Apparatus for 3D printing according to claim 1, wherein said tank (10) is removable.

3. Apparatus for 3D printing according to claim 1, wherein the rigid support (11) comprises a glass plate (17).

4. Apparatus for 3D printing according to claim 1, wherein the glass plate (17) comprises a borosilicate glass plate.

5. Apparatus for 3D printing according to claim 3, wherein applying the adhesive component to the rigid support increases a suction effect between the glass plate (17) of the rigid support (11) and the elastic membrane (23).

6. Apparatus for 3D printing according to claim 1, wherein an adhesion force between the rigid support (11) and the elastic membrane (23) is greater than an adhesion force generated between the elastic membrane (23) and a newly cured layer (27).

7. Apparatus for 3D printing according to claim 1, wherein the elastic membrane (23) triggers a peeling phenomenon by gently detaching from the newly cured layer (27).

8. Method for 3D printing of bottom-up photo-curing type comprising the following steps: a) providing the apparatus of claim 1; b) forming a solid layer (27) on an extraction plate (25) by photo-curing a photo-curing liquid material (24) comprised inside a tank (10), in the space between an extraction plate (25) and an elastic membrane (23), wherein a rigid support (11) is in contact with the lower side of said elastic membrane (23); c) removing said rigid support (11) from said elastic membrane (23), said elastic membrane (23) remaining attached to said rigid support (11), with progressive detachment of said extraction plate (25); d) lifting of said extraction plate (25), up to a new position of forming a solid layer (27); e) returning of said rigid support (11) to its initial position, in contact with said elastic membrane (23).

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The present invention will now be described, for illustrative but not limitative purposes, according to a preferred embodiment thereof, with particular reference to the figures of the enclosed drawings, in which:

(2) FIG. 1 shows a perspective view from above of the characteristic elements of an apparatus for 3D printing of bottom-up photo-curing type, with independent elastic membrane system and pivoting reference according to the present invention, exploded in its main components,

(3) FIG. 2 shows a perspective view from above of the elements of the apparatus of FIG. 1, exploded in all its components,

(4) FIG. 3 shows a perspective view from below of the elements of the apparatus of FIG. 1, exploded in all its components,

(5) FIG. 4 shows a perspective view from below of the elements of the apparatus of FIG. 1, assembled, in a first phase of use,

(6) FIG. 5 shows a perspective view from above of the elements of the apparatus of FIG. 1, assembled, in a second phase of use,

(7) FIGS. 6A, 6B, 6C, 6D, 6E, 6F and 6G show a schematic representation of the elements of the apparatus of FIG. 1, assembled, in the steps of a printing method which does not form the subject of the present invention, and

(8) FIGS. 7A, 7B, 7C and 7D show a schematic representation of the elements of the apparatus of FIG. 1, assembled, in the steps of a printing method according to the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

(9) Making preliminary reference to FIGS. 1-5, the characterising elements of an apparatus for 3D printing of bottom-up photo-curing type, with independent elastic membrane system and tilting reference according to the present invention essentially comprise a tank 10 (which can be considered as a consumable), a rigid support 11, transparent to the radiation of a light source, arranged on the side of said rigid support 11 opposite with respect to said tank 10, and a movement system 20. The tank 10 and the rigid support 11 are coupled to the rest of the apparatus (not shown) through a support plate 12, which has a hole 13, for the passage of the radiation coming from the light source.

(10) In particular, the bottom 14 of the tank 10 consists of an elastic type membrane (free field elastic membrane), inserted with pre-tension (that is with a certain degree of tension) between the walls 15 of the tank 10 and a locking mask 16 of the pre-tensioned elastic membrane.

(11) The rigid support 11 consists of a glass plate 17, in particular borosilicate glass, housed on a drum 18. A first side of the drum 18 is coupled with possibility of rotation around a hinge axis to the support plate 12, while on a second side of the drum 18, opposite to said first side, there is an element 19 for coupling with a handling system 20, which in the embodiment shown in FIGS. 3 and 4 is constituted by a rod-crank mechanism 21, mounted on a rotary motor 22. The rotation of the rotary motor 22, transmitted to the drum 18 as a reciprocating rectilinear movement by means of the connecting rod-crank mechanism 21 and coupling element 19, rotates the rigid support 11 around the hinging axis, moving it away and subsequently bringing it closer to the bottom of the tank 10, which supports the elastic membrane, which instead remain fixed.

(12) With reference to FIGS. 6A-6G, in which in addition to the elements already described with reference to the previous figures, the elastic membrane 23, a liquid resin 24 (contained in the tank 10), an extraction plate 25 and a light source 26 are also shown, the steps of a printing method which does not form the subject of the present invention are shown.

(13) In a first step, shown in FIG. 6A, the rigid support 11, transparent to the radiation emitted by the light source 26, is in plane, in contact with the elastic membrane 23, which therefore rests on the rigid support 11 and more precisely on the glass plate 17. The extraction plate 25 is in the position closest to the elastic membrane 23, or at the distance of a layer from the elastic membrane 23, the space between the extraction plate 25 and the elastic membrane 23 being occupied by the liquid resin 24. In this first phase the light source 26 is on and begins to polymerize the liquid resin 26.

(14) In the next step, shown in FIG. 6B, the formation of the first layer is completed and the light source 26 is then turned off. In this step, the glass plate 17 of the rigid support 11 is rigidly attached to the bottom of the elastic membrane 23. The system therefore behaves like a 3D printing machine of classic bottom-up photo-curing type, and the forming layer is compressed between two rigid bodies.

(15) The result is the advantage of a high compression and precision of the layer (there is not the problem of the rope that would be generated by an elastic membrane without reference), but at the same time, the suction effect would be generated.

(16) To counteract the onset of the suction effect, in the subsequent phase, shown in FIG. 6C, the rigid support 11 is made to rotate around the hinging axis, detaching itself from the elastic membrane 23, which instead remains attached by suction effect to the just cured layer 27. In this step, a linear support, rather than a rotary movement around an axis, of the rigid support 11 under the elastic membrane 23 would create a greater mechanical stress, which for applications where greater precision is required would be detrimental.

(17) In the phase shown in FIG. 6D, the extraction plate 25 is made to rise to detach the layer 27 from the elastic membrane 23. The elastic membrane 23 triggers the peeling phenomenon by gently detaching from the newly formed layer 27. Therefore, the removal of the rigid support 11 from the base of the elastic membrane 23 allows the layer 27 to be detached, reducing/eliminating the previously described suction effect.

(18) In the following step, shown in FIG. 6E, the elastic membrane 23, detaching itself from the layer 27, returns to the rest position. Under the load of the resin 24 and by its own weight the elastic membrane 23 could generate a buckling due to the phenomenon of the rope, which however in this case does not affect the shape of the layer 27.

(19) Subsequently, as shown in FIG. 6F, the extraction plate 25 descends towards the bottom of the tank 10, returning to the printing position of the next layer.

(20) Finally, in the last step, shown with reference to FIG. 6G, the rigid support 11 is made to rotate around the hinging axis to return to the starting position, to then proceed with the formation of a subsequent layer.

(21) It is evident that the described printing process allows to reduce/remove the suction effect, allowing a delicate removal of the elastic membrane 23 from the newly formed layer 27, thanks to the peeling effect consequent to the progressive removal of the extraction plate 25 from the elastic membrane 23. At the same time, during the formation of the layer 27, the position of the rigid support 11 allows to realize a layer 27 with a high compression and precision.

(22) In a variant of the apparatus and of the 3D printing method according to the present invention, shown with reference to FIGS. 7A-7D, on the interface between the rigid support 11 and the elastic membrane 23 a device is applied which involves an adherence between the rigid support 11 and the elastic membrane 23 higher than that which is established between the same elastic membrane 23 and the newly formed layer 27, inducing a peeling phenomenon between the rigid support 11 and the elastic membrane 23. This arrangement could, by way of example, comprise a pressure/decompression system, or the presence of a layer 28 of adhesive component disposed between the rigid support 11 and the elastic membrane 23.

(23) In particular, in the variant shown with reference to FIGS. 7A-7D, on the interface between the rigid support 11 and the elastic membrane 23 a layer 28 of adhesive component is applied, with the consequence of increasing the suction effect between the glass plate 17 of the rigid support 11 and the elastic membrane 23. It follows a different 3D printing process than the one described with reference to FIGS. 6A-6G.

(24) In particular, according to this different embodiment of the apparatus for 3D printing according to the present invention, the corresponding printing method comprises the following steps.

(25) In a first step, illustrated with reference to FIG. 7A, the rigid support 11, transparent to the radiation emitted by the light source 26, is in plane, in contact with the layer 28 of adhesive component applied to the lower surface of the elastic membrane 23, which then rests on the rigid support 11 and more precisely on the glass plate 17, with the intermediation of only the layer 28 of adhesive component. The extraction plate 25 is in the position closest to the elastic membrane 23, or at the distance of a layer from the elastic membrane 23, the space between the extraction plate 25 and the elastic membrane 23 being occupied by the liquid resin 24. In this first phase the light source 26 is on and begins to polymerize the liquid resin 26.

(26) In the following step, shown in FIG. 7B, the formation of the first layer is completed and the light source 26 is then turned off. In this step, the glass plate 17 of the rigid support 11 is rigidly attached to the bottom of the elastic membrane 23, with the interposition of the layer 28 of adhesive component. In this case too, therefore, the system behaves like a classic 3D printing machine of bottom-up photo-curing type, and the layer under formation is compressed between two rigid bodies, with the consequent advantage of a high compression and precision of the layer (there is not the problem of the rope that would be generated by an elastic membranes without reference), but at the same time, the suction effect would be generated.

(27) To counteract the onset of the suction effect, in the subsequent phase, shown in FIG. 7C, the rigid support 11 is made to rotate around the hinging axis, but in this case, thanks to the presence of the layer 28 of adhesive component, the adhesion force between the rigid support 11 and the elastic membrane 23 is greater than the adhesion force generated between the elastic membrane 23 and the newly cured layer 27, so that the same rigid support 11 tends to carry with it the elastic membrane 23, allowing a controlled detachment (inverse peeling) of the elastic membrane 23 from the rigid support 11, with a consequent reduction of the mechanical stress to which the elastic membrane is subjected 23.

(28) Moreover, the removal of the elastic membrane 23 from the newly formed layer 27, which follows from the fact that the elastic membrane 23 tends to follow the rigid support 11 in its movement, generates a volume underlying the layer 27, which is filled by the liquid resin 24, thus increasing the filling speed of the space between the newly formed layer 27 and the elastic membrane 23 (refresh).

(29) This step, therefore, makes the need to remove the extraction plate 25 from the elastic membrane 23 and then move it closer again to proceed with the formation of a new layer unnecessary.

(30) In fact, as shown in FIG. 7D, in the subsequent step it is sufficient to slightly remove the extraction plate 25 and at the same time return the rigid support 11 to the starting position, so that the extraction plate 25 and the rigid support 11 are in the position for the generation of a new layer, and then the light source 26 can be switched back on.

(31) In FIG. 7C, the layer 28 of adhesive component is always shown adherent to the elastic membrane 23, but according to the present invention it is indifferent whether the layer 28 of adhesive component remains adherent to the elastic membrane 23, to the support 11 or partly to the elastic membrane 23 and partly to the support 11. Furthermore, the printing method according to the present invention may also occur without the need to add a layer 28 of adhesive component between the rigid support 11 and the elastic membrane 23, if the adhesion force generated by the suction effect between the glass plate 17 and the elastic membrane 23 is greater than the adhesion force generated between the same elastic membrane 23 and the newly cured layer 27

(32) The method of use of the apparatus for 3D printing according to the present invention therefore allows to reduce the mechanical stress of the object, saving three steps for the printing routines with respect to the method previously illustrated with reference to FIGS. 6A-6F, with a significant reduction of printing times and with a better surface quality of the object to be produced.

(33) The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that variations and/or modifications may be made by those skilled in the art without departing from the relative scope of protection, as defined by the attached claims.