ELECTROPHOTOGRAPHY-BASED ADDITIVE MANUFACTURING WITH OVERLAY CONTROL

• US 20150273767A1
• Filed: 04/01/2014
• Published: 10/01/2015
• Est. Priority Date: 04/01/2014
• Status: Active Grant

• Current Assignee: Evolve Additive Solutions, Inc.
• Original Assignee: Stratasys Incorporated
• Inventors: Batchelder, J. Samuel, Farah, Zeiter
• Granted Patent: US 9,688,027 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B29C 64/393 for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G03G 15/1625 on a base other than paper
• CPC Class Codes: G03G 15/224 Machines for forming tactile or three dimensional images by electrographic means, e.g. braille, 3d printing
• CPC Class Codes: G03G 15/24 whereby at least two steps are performed simultaneously
• CPC Class Codes: G03G 2215/1695 at the second or higher order transfer point

Abstract

A method and system for printing a three-dimensional part, which includes rotating a transfer belt with a developed layer, scanning the developed layer on the rotating transfer belt, pressing the developed layer into contact with an intermediate build surface of the three-dimensional part retained on a moveable build platform, scanning the pressed layer on the three-dimensional part, comparing the scanned layers to detect an overlay error, and adjusting a position of the moveable build platform relative to the transfer belt to reduce the overlay error for a subsequent developed layer.

Claims

1. An additive manufacturing system for printing a three-dimensional part, the additive manufacturing system comprising:

one or more imaging engines configured to develop layers of the three-dimensional part;

a build platform;

one or more gantry mechanisms configured to move the build platform;

a rotatable transfer medium configured to receive the developed layers from the one or more imaging engines, and to transfer the developed layers onto intermediate build surfaces of the three-dimensional part on the build platform in a layer-by-layer manner;

one or more imaging sensors configured to scan the developed layers on the rotatable transfer medium and on the three-dimensional part, and to transmit data relating to the scans; and

a controller assembly configured to receive the transmitted data from the one or more imaging sensors, to detect overlay errors from the scans, and to adjust the one or more gantry mechanisms to reduce the overlay errors.

2. The additive manufacturing system of claim 1, wherein at least one of the imaging sensors is located upstream along the rotatable transfer belt relative to a transfer location of the developed layers onto the intermediate build surfaces.

3. The additive manufacturing system of claim 2, wherein at least a second of the imaging sensors is located downstream from the transfer location along a direction of movement of the build platform.

4. The additive manufacturing system of claim 2, wherein at least a second of the imaging sensors is located downstream from the transfer location along the rotatable transfer medium.

5. The additive manufacturing system of claim 1, wherein the one or more imaging sensors comprise at least one line scan camera.

6. The additive manufacturing system of claim 1, wherein the rotatable transfer medium comprises a rotatable transfer belt, wherein the additive manufacturing system further comprises a nip roller engaged with the rotatable transfer belt, and wherein the one or more imaging sensors configured to scan the developed layers on the rotatable transfer belt at an engagement location of the nip roller and the rotatable transfer belt.

7. The additive manufacturing system of claim 1, wherein the one or more gantry mechanisms comprise:

a first gantry mechanism configured to move the build platform in a process direction; and

a second gantry mechanism configured to move the build platform in a second direction that is perpendicular to the process direction.

8. A method for printing a three-dimensional part with an additive manufacturing system, the method comprising:

producing a developed layer of a part material with an imaging engine of the additive manufacturing system;

transferring the developed layer from the imaging engine to a transfer medium of the additive manufacturing system;

rotating the transfer medium with the developed layer;

scanning the developed layer on the rotating transfer medium;

transferring the developed layer from the rotating transfer medium onto an intermediate build surface of the three-dimensional part retained on a moveable build platform;

scanning the pressed layer on the three-dimensional part;

comparing the scanned layers to detect an overlay error; and

adjusting a position of the moveable build platform relative to the transfer belt to reduce the overlay error for a subsequent developed layer.

9. The method of claim 8, wherein scanning the developed layer and scanning the transferred layer comprise imaging the developed layer and the transferred layer with at least one line scan camera.

10. The method of claim 8, wherein the overlay error comprises a first-axis overlay error in a process direction of the moveable build platform.

11. The method of claim 10, wherein the overlay error further comprises a second-axis overlay error in second direction that is perpendicular to the process direction of the moveable build platform.

13. The method of claim 8, and further comprising scanning the transfer belt after transferring the developed layer into contact with the intermediate build surface of the three-dimensional part.

14. The method of claim 8, wherein comparing the scanned layers to detect the overlay error comprises computationally comparing the scanned layers with a controller assembly of the additive manufacturing system.

15. A method for reducing an overlay error in an additive manufacturing system, the method comprising:

rotating a transfer medium of the additive manufacturing system having a developed layer;

scanning the developed layer on the rotating transfer medium;

transferring the developed layer from the rotating transfer medium onto an intermediate build surface of a three-dimensional part retained on a build platform of the additive manufacturing system;

moving the build platform with the pressed layer in a process direction;

scanning the pressed layer on the three-dimensional part;

comparing the scanned layers to detect the overlay error; and

adjusting a position of the build platform in a direction that is perpendicular to the process direction, based on the detected overlay error.

16. The method of claim 15, wherein transferring the developed layer from the rotating transfer medium onto the intermediate build surface of the three-dimensional part comprises pressing the developed layer between a nip roller and the intermediate build surface of the three-dimensional part.

17. The method of claim 15, wherein scanning the pressed layer on the three-dimensional part comprises imaging the pressed layer with a line scan camera.

18. The method of claim 15, and further comprising adjusting an operation of a gantry mechanism that moves the build platform in the process direction, based on the detected overlay error.

19. The method of claim 15, and further comprising scanning the transfer medium after transferring the developed layer from the rotating transfer medium onto the intermediate build surface of the three-dimensional part.

20. The method of claim 15, wherein comparing the scanned layers to detect the overlay error comprises computationally comparing the scanned layers with a controller assembly of the additive manufacturing system.