System and method for high power diode based additive manufacturing

• US 10,569,363 B2
• Filed: 05/03/2016
• Issued: 02/25/2020
• Est. Priority Date: 03/05/2013
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Inventors: El-Dasher, Bassem S., Bayramian, Andrew, Demuth, James A., Farmer, Joseph C., Torres, Sharon G.
• Primary Examiner(s): Sanders, James
• Application Number:
  US15/145,402
• Publication Number:
  US 20160243652A1
• Time in Patent Office: 1,393 Days
• CPC Class Codes: B22F 10/20 Direct sintering or melting
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/30 Process control
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 12/43 pulsed; frequency modulated
• CPC Class Codes: B22F 12/44 characterised by the configuration of the radiation means
• CPC Class Codes: B22F 12/55 Two or more means for feeding material
• CPC Class Codes: B23K 26/042 Automatically aligning the laser beam
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/0643 comprising mirrors
• CPC Class Codes: B23K 26/066 by using masks
• CPC Class Codes: B23K 26/144 the fluid stream containing particles, e.g. powder
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• 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: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: C22C 32/0026 Matrix based on Ni, Co, Cr or alloys thereof
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

A system is disclosed for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate. The system may make use of a diode array for generating an optical signal sufficient to melt a powdered material of the substrate. A mask may be used for preventing a first predetermined portion of the optical signal from reaching the substrate, while allowing a second predetermined portion to reach the substrate. At least one processor may be used for controlling an output of the diode array.

Claims

1. A system for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate, the system comprising:

a dynamically controllable, two dimensional mask having a two-dimensional array of addressable pixels;

an optical subsystem for generating an optical signal comprised of electromagnetic radiation sufficient to melt or sinter a powdered material of the substrate, the optical subsystem being controllable so as to generate a plurality of different power levels, with a specific one of said power levels being selectable based on a specific material being used to form a 3D part;

the optical subsystem being able to generate the electromagnetic radiation with an average power density of greater than 200 W/cm² over the duration of the signal, and producing a beam having an area sufficient to illuminate substantially a full area of the dynamically controllable two dimensional mask at one time, and the average power density being sufficient to melt a powdered material;

the dynamically controllable, two dimensional mask receiving the optical signal and controllably selecting portions of the optical signal passing therethrough such that a first selected portion of the optical signal passes through the mask, and a second selected portion of the optical signal also passes through the mask, the mask permitting one of the first and second selected second portions to reach the powdered material, and the mask causing the other one of the first and second selected portions to be prevented from reaching the powdered material, and the mask absorbing only a portion of the electromagnetic radiation;

at least one processor which dynamically controls both the mask and the optical subsystem, and is configured to adjust a power level of the optical signal taking into account a composition of the powdered material; and

a relay telescope arranged upstream of the powdered material, relative to a direction of travel of the optical signal, the relay telescope being configured to receive an array image and to provide control over tiles within the array image to help facilitate melting in a single operation performed on each new layer of powdered material, in a layer-by layer sequence of operations.

2. The system of claim 1, wherein the optical subsystem comprises a diode array.

3. The system of claim 2, wherein the diode array is configured to provide the power density of at least about 10 kW/cm² to about 100 kW/cm² at a two percent duty cycle.

4. The system of claim 1, wherein the mask comprises:

a liquid crystal module; and

a polarizing element, the polarizing element operating to alter a polarization of the second portion of the optical signal after the second portion has passed through the liquid crystal module.

5. The system of claim 4, wherein the liquid crystal module comprises a computer controllable liquid crystal module configured to be digitally controlled by the processor.

6. The system of claim 4, wherein the polarizing element comprises a polarizing mirror.

20. The system of claim 1, wherein the powdered material forming the substrate comprises a material that is substantially absorptive to the optical signal.

21. The system of claim 20, wherein the powdered material comprises at least one of Iron, Titanium, Aluminum, Tungsten and oxide dispersion strengthened (ODS) steel.

7. A system for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate, the system comprising:

a dynamically controllable mask having an addressable two dimensional array of pixels;

an optical subsystem configured to generate a pulsed optical signal forming electromagnetic radiation sufficient in optical intensity to melt a powdered material of the substrate, the optical subsystem being controllable so as to generate a plurality of different power levels, with a specific one of said power levels being selectable based on a specific material being used to form a 3D part;

the electromagnetic radiation able to produce a power density of greater than at least about 10 kW/cm² and the pulsed optical signal forming a beam having dimensions sufficient to span substantially an entire two-dimensional area of the mask at once, and to be applied for a time duration sufficient to melt a powdered material forming a powder bed, where the powder bed forms the substrate;

the mask configured to pass first and second portions of the optical signal through the mask, but to selectively control polarizations of the first or second portions to permit one of the first or second portions to reach the powdered material to form an array image, and thus to melt the powdered material, while preventing the other one of the first or second portions from reaching the powdered material;

a processor for determining which one or more pixels of the mask need to be controlled in a manner such that only the one of the first or second portions of the optical signal reach the powdered material, and controlling on and off operation of the optical subsystem to enable the beam of the optical subsystem to be applied to the powdered material after the mask has been controlled to define the first and second portions, and where the processor is used to control the optical subsystem and the mask to selectively define and fuse select subportions of each layer of the part in a layer-by-layer sequence of operations; and

a relay telescope arranged upstream of the powder bed, relative to a direction of travel of the pulsed optical signal, the relay telescope being configured to receive the array image and to provide control over tiles within the array image to help facilitate melting in a single operation performed on each new layer of powdered material, in the layer-by-layer sequence of operations.

8. The system of claim 7, wherein the mask forms a liquid crystal polarization rotator having a liquid crystal module and a polarizer interposed between the optical subsystem and the substrate, the liquid crystal polarization rotator operating to rotate a polarization of one or the other of the first or second portions of the pulsed optical signal passing therethrough while allowing the other to pass therethrough without being rotated, and the polarizer operating to reject the one of the first or second portions that has been rotated.

9. The system of claim 8, wherein the liquid crystal module of the mask includes a plurality of pixels arranged in a two dimensional pattern that are individually controlled.

10. The system of claim 7, wherein:

the optical subsystem comprises a diode array which is configured to be electronically controlled; and

wherein the processor is configured to electronically control the diode array to control on and off operation of the diode array.

11. The system of claim 7, wherein the mask is configured to be digitally controlled by the processor.

12. The system of claim 7, wherein the mask is electronically addressable by the processor to prevent selected areas of the substrate from being exposed to the pulsed optical signal from the optical subsystem.

13. The system of claim 7, wherein the mask comprises a polarizing element.

14. The system of claim 8, wherein the polarizing element comprises a polarizing mirror disposed at a 45 degree angle from a plane that the pulsed optical signal from the optical subsystem travels in.

15. The system of claim 7, wherein the optical subsystem comprises a diode array configured to generate a power output of at least about 10 kW/cm² at a duty cycle of about two percent.

16. A system for performing an Additive Manufacturing (AM) fabrication process on a powdered material forming a substrate, the system comprising:

a dynamically controllable mask having an addressable two dimensional array of pixels;

an optical subsystem for generating a pulsed optical signal sufficient in optical intensity to melt a powdered material of the substrate, the optical subsystem being controllable so as to generate a plurality of different power levels, with a specific one of said power levels being selectable based on a specific material being used to form a 3D part, and further creating the optical signal as a beam having an area which illuminates substantially an entire area of the mask at one time;

the optical subsystem able to generate the optical signal with an average power density of greater than 200 W/cm² over the duration of the signal;

the mask including a liquid crystal module having a plurality of addressable regions of pixels, with the pixels being independently controllable, and a polarizer disposed downstream of the liquid crystal module, the mask being controllable to pass a first portion of the optical signal through the mask without causing any polarization rotation of the first portion, and to pass a second portion of the optical signal through the mask but to cause a predetermined degree of polarization rotation of the second portion;

one of the first and second portions being used to melt the powdered material, and the other of the first and second portions not being used to melt the powdered material; and

a processor for dynamically controlling specific pixels of the mask, and operation of the optical subsystem, so that the optical signal is generated at select times, and with a selected power level, to melt only select portions of the powdered material in each new layer of powdered material, in a layer-by-layer sequence of operations; and

a relay telescope arranged upstream of the powdered material, relative to a direction of travel of the pulsed optical signal, the relay telescope being configured to receive an array image and to provide control over tiles within the array image to help facilitate melting in a single operation performed on each new layer of powdered material;

in the layer-by-layer sequence of operations.

17. The system of claim 16, wherein the liquid crystal module comprises a computer controllable liquid crystal module configured to be digitally controlled by the processor.

18. The system of claim 16, wherein the optical subsystem comprises a diode array which is comprised of a plurality of diode emitters.

19. The system of claim 16, wherein:

the optical subsystem is configured to be electronically controlled by the processor; and

wherein the processor is configured to electronically control the optical subsystem to control on and off operation of a diode array.