METHOD FOR COMPUTATIONALLY DESIGNING RE-USABLE FLEXIBLE MOLDS FOR THE REPRODUCTION OF A AN OBJECT

Abstract

The invention relates to a method for computationally designing re-usable silicone molds for the reproduction of an object, wherein the silicone mold is fillable with casting material, for example, but not limited to, resin, to form the object.

Claims

1. Method for computationally designing at least one re-usable flexible mold for the reproduction of an object, wherein the flexible mold is at least two-pieced and fillable with casting material to form the object to be reproduced within the flexible mold, wherein the flexible mold is comprised of a flexible casting material, said method for computationally designing comprising the following steps: a) taking as an initial input (IN) a digital surface description (D) of the object to be reproduced, said input (IN) comprising a closed surface mesh (Mi) of the object to be reproduced, said initial closed surface mesh (Mi) being aligned with a surface of the object to be reproduced; b) calculating the flexible mold by executing the following steps: b1) separating the mesh into a number of connected surface patches (P1, P2), wherein each surface patch (P1, P2) is associated with a patch-individual parting direction and is selected either: b1_1) based on an heuristic estimation of the effort for removal of each patch (P1, P2) from the flexible mold and wherein a design and number of patches (P1, P2) is selected based on a minimization algorithm; or b1_2) based on a volume based calculation model, wherein a fictive volume enclosing the object to be reproduced is determined and wherein shortest paths from the surface of the mesh (Mi) to an outer boundary of the volume are determined for each point of the surface mesh (Mi), thus yielding potential extraction directions that are associated along the surface of the mesh (Mi), wherein the potential extraction directions are compared along the surface of mesh (Mi) and wherein the patches (P1, P2) are determined based on detected discontinuity of the potential extraction directions; b2) calculating the flexible mold based on the surfaces patches (P1, P2) yielded in step b1), wherein the number of pieces of the flexible mold corresponds with the number of patches (P1, P2); c) calculating a process of production of the flexible mold, wherein the calculation comprises a selection of either: c_1) calculating a corresponding rigid metamold for casting the flexible mold yielded in step b); or c_2) calculating a process for additively manufacturing the flexible mold; and d) yielding a design of the flexible mold of step b) and a result of the calculation of the process of production according to step c) as an output (OUT).

2. The according to claim 1, wherein the flexible mold includes a sealing dam or a sealing lip for closing the flexible mold.

3. The method according to claim 1, wherein an optimal orientation of the flexible mold with regard to Earth's gravitational field is calculated according to an optimization algorithm (OA).

4. The method according to claim 3, wherein the optimization algorithm (OA) is also configured to determine an optimal positioning of air vents within the flexible mold or of inlets for pouring in the flexible casting material.

5. The method according to claim 1, wherein the calculation of step c_1) determines if at least one membrane is to be included in the corresponding rigid metamold in order to insert a corresponding cut into the flexible mold, such that non-destructive removal of a cured object is possible from the flexible mold, and if so, also to determine a shape of the at least one membrane.

6. The method according to claim 1, wherein calculation of step c_2) determines if at least one cut is required in the flexible mold, such that non-destructive removal of the flexible mold from a cured object is possible, and if so, also to determine the shape of the at least one cut.

7. The method according to claim 5, wherein the calculation of the at least one membrane is computed by detecting tunnels loops in the digital surface description (D).

8. The method according to claim 5, wherein the calculation of the at least one membrane is computed by detecting discontinuities in the a direction of the shortest paths throughout the volume around the digital surface description (D).

9. The method according to claim 1, wherein the calculation of each surface patch according to step b1) is associated with the patch-individual parting direction and is selected according to step b1_1) of claim 1, wherein the mesh comprises faces, wherein a visibility of a face is evaluated from a number of different viewpoints determined by potential parting directions, wherein neighbouring faces having at least one similar potential parting direction are grouped into a potential patch, splitting the mesh into a number of potential patches, and wherein an optimal set of patches is determined by the following criterions: {minimizing number of patches within a set, while ensuring that the entirety of the patches cover the entire mesh; minimizing the effort of removal of the patches (P1, P2) within a set}.

10. The method according to claim 1, wherein the object or a corresponding cavity and the flexible mold is separated by at least one parting line (PL), wherein the at least one parting line (PL) is defined as at least one closed curve (C) in 3D space that is shaped when the two pieces (U, L) of the flexible mold and the corresponding cavity or the object within the flexible mold meet one another, wherein the parting line (PL) is a curve that does not lie entirely within a single plane.

11. A method for reproduction of the object by using the flexible mold designed in accordance with claim 1, comprising steps of: e) filling the flexible mold with the flexible casting material, and f) non-destructive removal of a cured object from the flexible mold.

12. The method according to claim 11, wherein the flexible mold is produced by 3D-printing.

13. The method according to claim 11, wherein the flexible mold is produced by casting the flexible curable material into a corresponding metamold.

14. A re-usable flexible mold designed by the method of claim 1.

15. An object reproduced by the method according to claim 13.

16. The method according to claim 1 for computationally designing the at least one re-usable flexible mold for the reproduction of the object, wherein the flexible mold is fillable with a resin casting material.

17. The method according to claim 1 wherein step c_2) includes calculating a process for 3D printing the flexible mold.

18. The method according to claim 6, wherein the calculation of the at least one cut is computed by detecting tunnels loops in the digital surface description (D).

19. The method according to claim 6, wherein the calculation of the at least one cut is computed by detecting discontinuities in a direction of the shortest paths throughout the volume around the digital surface description (D).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In the following, in order to further demonstrate the present invention, illustrative and non-restrictive embodiments are discussed, as shown in the drawings, which show:

[0045] FIG. 1 a schematic diagram showing the relevant steps of the method according to the invention,

[0046] FIGS. 2 and 3 views of a mythical creature as an example for an object to be reproduced,

[0047] FIG. 4 a digital representation of the creature according to FIGS. 2 and 3,

[0048] FIG. 5 an exemplary split of the mesh of FIG. 4 into two patches,

[0049] FIGS. 6 and 7 exemplary metamolds,

[0050] FIGS. 8 and 9 exemplary re-usable flexible molds, and

[0051] FIG. 10 a perspective view of a cup as an example for an object to be reproduced.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0052] In the following, identical reference signs used in the figures depict identical features if not stated otherwise. Reference is also made to the drawings and description disclosed in the attached documents “Metamolds: Computational Design of Silicone Molds”, and “Volume-Aware Design of Composite Molds”, said documents being hereby incorporated by reference.

[0053] FIG. 1 shows schematic diagram showing the relevant steps of the method according to the invention.

[0054] FIG. 2 shows perspective view of a mythical creature as an example for an object 2 to be reproduced. FIG. 3 shows yet another view of the creature of FIG. 2.

[0055] FIG. 4 shows a digital surface description D, in particular a digital representation, of the creature according to FIGS. 2 and 3. Therein, the representation comprises an initial mesh Mi, that is—based on an algorithm according to the invention, rearranged into a minimized number of patches, wherein in the following example the algorithm is able to reduce the number of patches down to two, namely P1 and P2 (see FIG. 5). Consequently, the flexible mold resulting from this calculation will have two pieces, namely one piece corresponding to P1 and one piece corresponding to P2. The line referenced as “PL” shown in FIG. 5 represents the parting line between the patches P1 and P2 and the respective pieces of the mold.

[0056] The invention discloses two different algorithms two calculate these patches, namely either [0057] b1_1) based on an heuristic estimation of the effort for removal of each patch from the flexible mold and wherein the design and number of patches is selected based on an minimization algorithm (see paper “Metamolds: Computational Design of Silicone Molds”), or [0058] b1_2) based on a volume based calculation model, wherein a fictive volume enclosing the object to be reproduced is determined and wherein shortest paths from the surface of the mesh to the outer boundary of the volume are determined for each point of the surface mesh, thus yielding potential extraction directions that are associated along the surface of the mesh, wherein the potential extraction directions are compared along the surface of mesh and wherein the patches are determined based on detected discontinuity of the potential extraction directions (see paper “Volume-Aware Design of Composite Molds”).

[0059] FIGS. 6 and 7 show exemplary metamolds 3′ and 3″, i.e. molds calculated and produced in order to manufacture the corresponding flexible molds 1′ and 1″ (see FIGS. 8 and 9). In detail, the flexible molds 1′ and 1″ are casted by covering the rigid metamolds 3′ and 3″ with the elastic material, or with a coverage that is filled with liquified elastic material, that can be cured later on like silicone. By alternative, the flexible molds 1′ and 1″ could also be manufactured by 3D-printing or another suitable method. Currently, 3D-printers printing silicone are under development and already commercially available.

[0060] In other words, the present invention relates to a method for computationally designing at least one re-usable flexible mold 1′ and 1″ for the reproduction of an object 2, wherein the flexible mold 1′, 1″ is at least two-pieced and fillable with casting material, for example, but not limited to, resin, to form the object 2 to be reproduced within the mold 1, wherein the mold 1 consists of flexible material, comprising the following steps:

[0061] a) taking as an initial input IN a digital surface description D of the object 2 to be reproduced, said input IN comprising a closed surface mesh Mi of the object 2 to be reproduced, said initial closed surface mesh Mi being aligned with surface of the object 2 to be reproduced,

[0062] b) calculating an at least two-pieced flexible mold 1′, 1″ by executing the following steps

[0063] b1) separating the mesh Mi into a number of connected surface patches P1, P2, wherein each surface patch P1, P2 is associated with an patch-individual parting direction and is selected either

[0064] b1_1) based on an heuristic estimation of the effort for removal of each patch P1, P2 from the flexible mold 1′, 1″ and wherein the design and number of patches P1, P2 is selected based on an minimization algorithm, or

[0065] b1_2) based on a volume based calculation model, wherein a fictive volume enclosing the object to be reproduced is determined and wherein shortest paths from the surface of the mesh Mi to the outer boundary of the volume (see for instance section 4.1 of the paper “Volume-Aware Design of Composite Molds”) are determined for each point of the surface mesh Mi, thus yielding potential extraction directions that are associated along the surface of the mesh Mi, wherein the potential extraction directions are compared along the surface of mesh Mi and wherein the patches are determined based on detected discontinuity of the potential extraction directions,

[0066] b2) calculating the at least two-pieced flexible mold 1′, 1″ based on the surfaces patches P1, P2 yielded in step b1), wherein the number of pieces of the mold 1′, 1″ corresponds, namely equals, with the number of patches P1, P2,

[0067] c) calculating the process of production of the at least two-pieced flexible mold 1′, 1″, wherein the calculation comprises a selection of either

[0068] c_1) calculating a corresponding rigid metamold 3′, 3″ for casting the flexible mold 1′, 1″ yielded in step b), or

[0069] c_2) calculating a process for additively manufacturing, in particular 3D printing, the flexible mold 1′, 1″,

[0070] d) yielding the design of the at least two-pieced flexible mold 1′, 1″ of step b) and the result of the calculation of the process of production according to of step c) as an output OUT.

[0071] As can be seen FIGS. 8 and 9 the flexible mold 1′, 1″ comprises a sealing dam 4 for closing the two-pieced mold.

[0072] FIG. 10 shows a perspective view of a cup as an example for an object 2 to be reproduced. The line references as “PL” shows the parting line between the respective two pieces of an exemplary mold for reproducing this object. Furthermore, one additional cut location is shown, which can be realized as a membrane 5 that is included in the rigid metamold in order to insert a corresponding cut into the flexible mold, such that the non-destructive removal of the cured object is possible from the flexible mold.

[0073] Exemplary drawings showing the process of reproducing an object by filling flexible molds with casting material can also be seen in FIG. 9 of the paper “Volume-Aware Design of Composite Molds”, which are explained correspondingly in said paper.