APERTURE SYSTEM FOR PRECERAMIC POLYMER STEREOLITHOGRAPHY

• US 20180341184A1
• Filed: 05/26/2017
• Published: 11/29/2018
• Est. Priority Date: 05/26/2017
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Hundley, Jacob M., Eckel, Zak C., Schueller, Emily C., Biesboer, Scott M.
• Granted Patent: US 11,079,683 B2
• Time in Patent Office: Days
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 35/0888 using transparant moulds
• CPC Class Codes: B29C 37/0075 using release sheets
• CPC Class Codes: B29C 64/124 using layers of liquid which are selectively solidified
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/255 Enclosures for the building material, e.g. powder containers
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: G03F 7/70416 2.5D lithography

Abstract

An aperture system for a bottom-up stereolithography device including a reservoir having a lower opening, an aperture including a flexible membrane positioned within the reservoir and covering the lower opening, and a boundary seal positioned around a periphery of the flexible membrane, the boundary seal including one or more boundary seal components and immobilizing the periphery of the flexible membrane against the reservoir. The flexible membrane is formed of a material having a low affinity for a liquid resin used in the stereolithography device as well as cured photopolymer resin parts produced by the device. In addition, the flexible membrane is able to deform as the cured resin part is pulled away from the aperture, thus enabling lower energy mixed mode adhesive failure to occur at the interface between the cured resin and the aperture and reducing the chance of cohesive damage to the cured photopolymer part.

Claims

1. An aperture system for a bottom-up stereolithography device, the aperture system comprising:

a reservoir having a lower opening;

an aperture, the aperture comprising;

a flexible membrane positioned within the reservoir and covering the lower opening; and

a boundary seal positioned around a periphery of the flexible membrane, the boundary seal comprising one or more boundary seal components and immobilizing the periphery of the flexible membrane against the reservoir.

2. The aperture system of claim 1, the aperture further comprising:

a transparent window under the flexible membrane and in the lower opening of the reservoir, the transparent window covering the lower opening; and

a compliant release layer between the transparent window and the flexible membrane in the lower opening of the reservoir, the compliant release layer covering the lower opening and having a low affinity for the flexible membrane.

3. The aperture system of claim 1, wherein the flexible membrane is configured to have a contact angle greater than about 40°

with a resin used for stereolithography.

4. The aperture system of claim 1, wherein the flexible membrane is configured to have an interlayer peel strength of less than about 200 N/m with a cured photopolymer resin part.

5. The aperture system of claim 1, wherein the flexible membrane comprises polystyrene (PS), polymethylpentene (PMP), cyclic olefin copolymers (COC), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), or a mixture thereof.

6. The aperture system of claim 1, wherein the flexible membrane has a thickness of about 10 μ

m to about 750 μ

m.

7. The aperture system of claim 1, wherein the boundary seal components comprise a reversible mechanical attachment.

8. The aperture system of claim 7, wherein the reversible mechanical attachment comprises a magnet having a magnetic force of about 5 lbs. to about 60 lbs.

9. The aperture system of claim 1, wherein the boundary seal components comprise an epoxy adhesive, an acrylate adhesive, a silicone sealant, a urethane sealant, or a mixture thereof.

10. The aperture system of claim 1, wherein the boundary seal components comprise a vacuum chuck to maintain contact between the flexible membrane and the reservoir.

11. The aperture system of claim 1, wherein the boundary seal comprises a resin exchange feature.

12. The aperture system of claim 2, wherein the transparent window comprises glass, polyethylene terephthalate (PET), biaxially-oriented polyethylene terephthalate (BOPET), polymethylpentene (PMP), cyclic olefin copolymers (COC), polycarbonate, polymethylmethacrylate (PMMA), or a mixture thereof.

13. The aperture system of claim 2, wherein the transparent window has a thickness of about 0.1 mm to about 16 mm.

14. The aperture system of claim 2, wherein the compliant release layer comprises silicone, urethane, fluorinated polymers, or a mixture thereof.

15. The aperture system of claim 2, wherein the compliant release layer comprises a gas or fluid, the gas or fluid comprising nitrogen, argon, air, water, an alcohol, an oil, a resin without a photoinitiator component, or a mixture thereof.

16. The aperture system of claim 2, wherein the compliant release layer has a thickness of about 0.1 mm to about 13 mm.

17. The aperture system of claim 1, the aperture further comprising a transparent window under the flexible membrane, wherein the flexible membrane and the transparent window are integrated and included in the lower opening as a single body without a compliant release layer therebetween.

18. The aperture system of claim 1, wherein the flexible membrane is suspended above an exposure source under tension without a compliant release layer or a window under the flexible membrane.

19. The aperture system of claim 2, the aperture further comprising a volume of gas or liquid between the flexible membrane and the compliant release layer.

20. The aperture system of claim 2, wherein the compliant release layer and transparent window are integrated and included in the lower opening as a single body.

21. A stereolithography device comprising:

a build platform;

a reservoir positioned below the build platform so that the build platform can be lowered into or raised out of the reservoir;

an aperture positioned within and covering a lower opening in a bottom floor of the reservoir;

and

an exposure source positioned below the reservoir and configured to emit a light that passes through the aperture;

wherein the aperture comprises;

a flexible membrane; and

a boundary seal positioned around a periphery of the flexible membrane, the boundary seal comprising one or more boundary seal components and immobilizing the periphery of the flexible membrane against the reservoir.