Additive manufacturing in metals with a fiber array laser source and adaptive multi-beam shaping

Patent metadata

Field	Value
Publication number	US-10589377-B2
Application number	US-201715642884-A
Country	US
Kind code	B2
Filing date	Jul 6, 2017
Priority date	Jul 6, 2017
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A system for LAM that uses a scalable array of individually controllable laser beams that are generated by a fiber array system to process materials into an object using a powder bed, wire feed, or direct deposition. The adaptive control of individual beams may include beam power, focal spot width, centroid position, scanning orientation, amplitude and frequency, piston phase and polarization states of individual beams. These characteristics can be independently adjusted to control LAM characteristics including microstructure, mechanical and surface quality characteristics. The system may also have a set of material sensors that gather information on a material and environment immediately before, during, and immediately after processing. This information can be used to adapt the material processing routine to improve LAM productivity and parts quality. The system also supports a variety of beam shaping methods that improve the quality of produced objects or mitigate processing issues.

First claim

The invention claimed is:

1. An additive manufacturing system comprising:
a manufacturing surface comprising a material and a target object;
a laser transmitter module operable to produce a set of laser beams to heat the material, comprising:
a fiber array laser head comprising a set of fiber-based laser transmitters, and
a multi-channel optical power amplifier system comprising one or more controllers, the multi-channel optical power amplifier system operable to provide laser power to each of the set of fiber-based laser transmitters, and to provide control signals to generate and modify spatiotemporal laser power distribution formed by the set of laser beams at the material;

a beam rastering system operable to position the set of laser beams relative to the target object;
a beam rastering controller, wherein the beam rastering controller is communicatively coupled with the laser transmitter module and the beam rastering system;
wherein the beam rastering controller is configured to:
receive a target object definition, the target object definition comprising a set of coordinates defining the target object, wherein a beam shaping method selected from a set of beam shaping methods is associated with each coordinate of the set of coordinates;
determine a preconfigured instruction set based upon the target object definition and provide a first portion of the preconfigured instruction set to the laser transmitter module and a second portion of the preconfigured instruction set to the beam rastering system; and
based on the preconfigured instruction set and for at least one coordinate of the set of coordinates, cause the beam rastering system to position the set of laser beams and cause the laser transmitter module to perform the beam shaping method.

2. The additive manufacturing system of claim 1 , wherein the laser transmitter module further comprises:
a set of sensors comprising one or more of:
a set of beam sensing modules, and
a set of material sensing modules; and

a set of beam forming optics operable to modify one or more of the set of laser beams, characterization of the material, and control of an additive manufacturing process based upon the output of the set of sensors;
wherein the one or more controllers are configured to:
receive a set of sensor data from the set of sensors;
determine a dynamic instruction set based upon the target object definition and the set of sensor data, the dynamic instruction set comprising a dynamic instruction set for a beam shaping method that is selected to improve the manufacturing process and quality of the target object; and
provide a first portion of the dynamic instruction set to the beam rastering controller;
wherein the dynamic instruction set is configured, for at least one coordinate of the set of coordinates, to guide the beam rastering system to position the set of laser beams and cause a dynamic beam shaping method to be performed based upon the dynamic instructions set for a beam shaping method.

3. The additive manufacturing system of claim 2 , wherein the set of material sensing modules comprises one or more of:
a manufacturing surface sensor comprising a first probe beam laser illuminator and a first optical receiver, configured to provide a first probe beam oriented and focused to precede a path of the set of beams and operable to determine characteristics of a powder material prior to a molten pool stage along a processing track;
a molten pool sensor comprising a second probe beam laser illuminator and a second optical receiver, configured to provide a second probe beam oriented and focused at the molten pool area and operable to determine characteristics of a molten pool; and
a processed track sensor comprising a third probe beam laser illuminator and a third optical receiver, configured to provide a third probe beam oriented and focused to follow a path of the set of laser beams behind of the molten pool and operable to determine characteristics of a processed track.

4. The additive manufacturing system of claim 1 , wherein the manufacturing surface is selected from the group consisting of:
a powder bed table;
a wire feed table; and
a direct energy deposition table.

5. The additive manufacturing system of claim 1 , wherein the one or more controllers are operable to control the characteristics of a set of laser beam focal spots, at the material surface, of the set of laser beams produced by the laser transmitter module, the characteristics comprising one or more of:
laser power of focal spot;
focal spot width;
focal spot centroid location;
focal spot steering frequency;
focal spot steering amplitude;
focal spot steering angle; and
focal spot polarization.

6. The additive manufacturing system of claim 1 , further comprising a beam splitter that redirects a portion of the set of laser beams to an optical imaging module, the optical imaging module comprising:
a conjugate image forming optic,
one or more beam splitters, and
a photo sensor comprising one or more of a photo-array sensor and a pinhole photo-detector,
wherein the optical imaging module is configured to produce a conjugate image of a set of focal spots of the set of laser beams, and determine a set of focal spot characteristics of the set of focal spots to be used for beam shaping,
wherein the photo sensor is located in the plane that is conjugated in respect to the plane of the set of focal spots at the material, and
wherein the one or more controllers are configured to control the set of focal spot characteristics during the performance of each beam shaping method.

7. The additive manufacturing system of claim 1 , wherein the set of beam shaping methods comprises one or more of:
coherent combining of a set of focal spots of the transmitted beams at the material;
incoherent combining of a set of focal spots of the transmitted beams at the material;
positioning of individual focal spot centroids;
controllable randomization of piston phases of a set of transmitted beams;
setting polarization states of the set of transmitted beams;
stair-mode scanning of coherently combined set of focal spots of the transmitted beams;
scanning of all or a set of beam focal spots; and
time-multiplexing of sets of the above beam shaping methods.

8. The additive manufacturing system of claim 7 , wherein the beam shaping method comprises a set of laser power spatial distribution configurations selected to improve the manufacturing process and quality of the target object, the set of laser power spatial distribution configurations comprising one or more of:
focal spots of multiple beams positioned in a line with a pre-selected power level for each beam along the line;
focal spots of multiple beams positioned in a two-dimensional pattern;
a one dimensional or two-dimensional pattern of laser power distribution produced by scanned focal spots of a single or a set or all multiple beams; and
a one-dimensional or two-dimensional pattern of laser power distribution produced by time-multiplexing of two or more of the set of beam shaping methods.

9. The additive manufacturing system of claim 1 , wherein the laser transmitter module further comprises one or more laser receivers, and wherein the laser transmitter module is operable as one or more laser transceivers.

10. The additive manufacturing system of claim 1 , wherein the laser transmitter module further comprises a set of beam forming optics comprising a virtual lens assembly, the virtual lens assembly comprising a set of beam forming optical systems, wherein each beam forming optical system is configured to independently focus a beam at a focal spot at the material, wherein the set of beam forming optic

Assignees

• Ii Vi Delaware Inc

Inventors

• Vorontsov Mikhail A

Classifications

• H01S3/0071

  Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction · CPC title

• H01S3/067

  Fibre lasers · CPC title

• B23K26/342

  Build-up welding · CPC title

• B23K26/0626

  Energy control of the laser beam (B23K26/0622 takes precedence) · CPC title

• B23K26/082

  Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head · CPC title