System and method for performing laser powder bed fusion using controlled, supplemental in situ surface heating to control microstructure and residual stresses in formed part

Patent metadata

Field	Value
Publication number	US-11858202-B2
Application number	US-201916365029-A
Country	US
Kind code	B2
Filing date	Mar 26, 2019
Priority date	Mar 26, 2019
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

The present disclosure relates to an additive manufacturing system for forming a part using a powder material. In one embodiment the system makes use of a primary heat generating subsystem to generate a fusing beam for heating and fusing at least one of select portions of a powder layer, or an entire area of a powder layer, deposited on a build plate. The system also incorporates a beam steering subsystem for steering the fusing beam over the powder layer. A supplemental heating subsystem is used to generate a wide area beam to heat a portion of the powder layer either prior to fusing, along with the fusing operation, or subsequent to fusing of the powder with the fusing beam. The wide area beam has an intensity which is insufficient to fuse the powder, and alters a microstructure of the powder layer as the powder layer is at least one of fused or as it cools, to thus relieve stress in the part.

First claim

What is claimed is:

1. An additive manufacturing system for forming a part using a powder material, the system comprising:
a computer configured to generate an electronic mask sizing control signal;
a primary heat generating subsystem responsive to the computer for generating a fusing beam for heating and fusing at least one of a plurality of select portions of a powder layer, or an entire area of a powder layer, deposited on a build plate;
a beam steering subsystem responsive to the computer, and including a first mask, for steering the fusing beam over the powder layer deposited on the build plate;
a supplemental heating subsystem for generating a wide area beam to heat a portion of the powder layer;
the supplemental heating subsystem including a second mask forming a portion of a computer controllable mask subsystem, the computer controllable mask subsystem being responsive to the electronic mask sizing control signal from the computer and configured to control a dimension and a shape of the wide area beam independently of the fusing beam, to enable illuminating two selected areas of the powder layer on the build plate with differing selected intensities and different beam coverage areas, through use of the wide area beam and the fusing beam;
the computer controlling the supplemental heating subsystem while simultaneously controlling the primary heat generating subsystem, and further such that the supplemental heating subsystem heats the portion of the powder layer at least one of:
prior to fusing of powder of the powder layer with the fusing beam;
simultaneously with fusing of the powder of the powder layer with the fusing beam; or
subsequent to fusing of the powder of the powder layer with the fusing beam;

the wide area beam being of an intensity which is insufficient to fuse the powder layer; and
the wide area beam operating to alter a microstructure of the powder layer as the powder layer is at least one of:
fused by the fusing beam, or
as the powder layer cools after being fused by the fusing beam,
to relieve stress in the part produced by thermal gradients created during operation of the fusing beam fusing the powder layer, and to control an overall thermal history of the powder layer while being acted on by the fusing beam and the wide area beam.

2. The system of claim 1 , wherein the supplemental heating subsystem is controlled by the computer to generate the wide area beam at selected times.

3. The system of claim 1 , wherein the supplemental heating subsystem comprises a diode laser.

4. The system of claim 1 , wherein the supplemental heating subsystem comprises a plurality of diode lasers.

5. The system of claim 1 , wherein the supplemental heating subsystem is controlled to generate the wide area beam and the fusing beam both prior to, and concurrently with, application of the fusing beam to the powder layer.

6. The system of claim 1 , wherein the supplemental heating subsystem is controlled to generate the wide area beam and the fusing beam simultaneously, and to maintain illumination of the wide area beam on a select area of the powder layer after the fusing beam has fused the select area and been turned off.

7. The system of claim 1 , wherein the supplemental heating subsystem is controlled to generate and apply the wide area beam to at least a select area of the powder layer prior to the fusing beam being used to begin fusing the select area, and during fusing of the select area, and after fusing of the select area is completed.

8. The system of claim 1 , further comprising a beam homogenizer configured to receive an output from the supplemental heating subsystem and to impart a uniform intensity to the wide area beam.

9. An additive manufacturing system for forming a part using a laser powder bed fusion manufacturing process, the system comprising:
a computer configured to generate a mask sizing control signal;
a primary heat generating subsystem including a diode laser responsive to the computer for generating a fusing beam having a first power level for heating and fusing at least one of a plurality of select portions of a powder laid down to form a powder layer on a build plate, or an entire area of the powder layer deposited on the build plate;
a beam steering subsystem including a first electronically controllable mask, and being responsive to the computer, for steering the fusing beam over the powder layer deposited on the build plate;
a supplemental heating subsystem for generating a wide area beam having a second power level lower than the first power level, to heat a desired portion of the powder layer;
the supplemental heating subsystem including a second electronically controllable mask, controlled by the computer independently of the first digitally controllable mask through the mask sizing control signal supplied from the computer, the mask sizing control signal configured to control a size and a pattern of the wide area beam independently of generation and control of the fusing beam, and the computer further configured to supply a power control signal to the supplemental heating subsystem to provide control over the second power level, to enable simultaneously illuminating two independent areas of the powder layer on the build plate with differing selected intensities created by the first and second power levels associated with the fusing beam and the wide area beam, respectively;
the computer controlling the supplemental heating subsystem simultaneously while controlling operation of the primary heat generation subsystem and the beam steering subsystem, and the supplemental heating subsystem further being configured to heat the desired portion of the powder layer at least one of:
prior to fusing of the powder with the fusing beam;
simultaneously with fusing of the powder with the fusing beam; or
subsequent to fusing of the powder with the fusing beam;

the wide area beam being of an intensity which is insufficient to fuse the powder; and
the wide area beam having an intensity controlled by the computer through the power control signal applied to the supplemental heating subsystem, and operating to alter a microstructure of the powder layer as the powder layer is at least one of fused, or as the powder layer cools, to relieve stress in the part caused by heating created by the fusing beam, and to control an overall thermal history of the powder layer while being acted on by the fusing beam and the wide area beam.

10. The system of claim 9 , wherein the supplemental heating subsystem is controlled by the computer to generate the wide area beam to illuminate at least one of the select portions of the powder layer while the fusing beam is fusing the at least one of the select portions.

11. The system of claim 9 , wherein the supplemental heating subsystem is controlled by the computer to generate the wide area beam and begin illuminating at least one of the select portions of the powder layer prior to using the fusing beam to begin fusing the at least one of the select portions.

12. The system of claim 9 , wherein the supplemental heating subsystem is controlled by the computer to generate the wide area beam and begin illuminating at least one of the select portions of the powder layer prior to using the fusing beam to begin fusing the at least one of the select portions, and to maintain the wide area beam in operation heating the at least one of the select portions while the fusing beam is applied to the at least one of the select portions.

13. The system of claim 9 , wherein the supplemental heating subsystem is controlled by the computer to generate the wide area beam and begin illuminating at least on

Assignees

• L Livermore Nat Security Llc

Inventors

• Smith William
• Guss Gabriel M
• Matthews Manyalibo Joseph
• Mckeown Joseph T
• Roehling John

Classifications

• B29C64/153 Primary

  using layers of powder being selectively joined, e.g. by selective laser sintering or melting · CPC title

• B22F10/28

  Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM] · CPC title

• B22F10/38

  to achieve specific product aspects, e.g. surface smoothness, density, porosity or hollow structures · CPC title

• B22F12/10

  Auxiliary heating means · CPC title

• B22F12/41

  characterised by the type, e.g. laser or electron beam · CPC title