Energy beam position verification

• US 9,664,505 B2
• Filed: 03/22/2016
• Issued: 05/30/2017
• Est. Priority Date: 08/20/2014
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Snis, Anders
• Primary Examiner(s): Kim, Kiho
• Application Number:
  US15/077,200
• Publication Number:
  US 20160202043A1
• Time in Patent Office: 434 Days
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/31 Calibration of process steps or apparatus settings, e.g. before or during manufacturing
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• CPC Class Codes: B23K 15/0013 Positioning or observing workpieces, e.g. with respect to the impact; Aligning, aiming or focusing electronbeams
• CPC Class Codes: B23K 15/0086 welding for purposes other than joining, e.g. built-up welding
• CPC Class Codes: B23K 15/02 Control circuits therefor
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/046 Automatically focusing the laser beam
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B23K 26/70 Auxiliary operations or equipment
• 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 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 15/00 Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons characterised by the use of optical techniques G01B9/00, G01B11/00
• CPC Class Codes: G01M 11/02 : Testing optical properties
• CPC Class Codes: G01P 21/00 : Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: G01P 3/36 : Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: H01J 37/244 : Detectors; Associated components or circuits therefor
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method for verifying a position of an energy beam spot, said method comprising the steps of: providing a calibrated energy beam having a first focus in a at least two positions at a work table, detecting said at least two positions of said energy beam spot on said work table created with said energy beam having said first focus, providing said calibrated energy beam having a second focus in said at least two positions at a work table, detecting said at least two positions of said energy beam spot on said work table created with said energy beam having said second focus, comparing said at least two positions created with said first and second focus, wherein said position of the energy beam is verified if said positions created with said first focus are deviating less than a predetermined distance from said positions created with said second focus.

Claims

1. A computer-implemented method for verifying a position of an energy beam spot, said method comprising the steps of:

providing, via at least one control unit containing a processor, an energy beam spot having a first focus directed toward at least two locations on a work table,

detecting at least two positions of said energy beam spot on said work table created with said energy beam having said first focus,

providing, via said at least one control unit, said energy beam spot having a second focus directed toward said at least two locations on said work table,

detecting at least two corresponding positions of said energy beam spot on said work table created with said energy beam having said second focus, and

comparing, via said at least one control unit, said at least two positions created with said first focus and said at least two corresponding positions created with said second focus, and verifying said position of the energy beam spot by verifying that said at least two positions created with said first focus deviate less than a predetermined distance from said corresponding at least two positions created with said second focus,

wherein said positions are detected by at least one of an IR-camera, a CCD-camera, a digital camera, a CMOS camera or a NIR-camera.

2. The computer-implemented method according to claim 1, wherein said at least two positions created with said first focus are a regularly 2-dimensional pattern.

3. The computer implemented method according to claim 1, wherein said at least two positions created with said first focus and said at least two corresponding positions created with said second focus are provided at identical positions as in a calibration process.

4. The computer-implemented method according to claim 1, wherein said at least two positions created with said first focus and said at least two corresponding positions created with said second focus are provided at different positions as in a calibration process.

5. The computer-implemented method according to claim 1, wherein said energy beam spot is an electron beam spot.

6. The computer-implemented method according to claim 1, wherein said work table is provided with a reference pattern.

7. The computer-implemented method according to claim 1, wherein said at least two locations are provided on said work table having a surface temperature above 500°

C.

8. The computer-implemented method according to claim 1, wherein said predetermined distance is less than 20 μ

m.

9. The computer-implemented method according to claim 1, further comprising a step of sending a warning signal when any one of said at least two positions provided with said first focus deviate more than said predetermined distance from said at least two corresponding positions provided with said second focus.

10. The computer-implemented method according to claim 1, wherein said energy beam spot with said first focus and said energy beam spot with said second focus are provided on the same work table.

11. The computer-implemented method according to claim 1, wherein a deviation between the at least two positions created with said first focus and the at least two corresponding positions created with said second focus is compensated for by altering a setting of a deflection coil.

12. The computer-implemented method according to claim 1, wherein:

the method further comprises the step of receiving and storing, within one or more memory storage areas, a model of at least one three-dimensional article; and

at least one of the varying, comparing, or repeating steps is performed via execution of one or more computer processors.

13. The computer-implemented method according to claim 1, wherein:

the method is further configured for verifying a deflection speed of the energy beam spot; and

the method further comprises the steps of, via said at least one control unit;

generating a predetermined pattern on the work table with said energy beam spot while deflecting said energy beam spot with a first deflection speed;

detecting first positions of said energy beam spot on said work table created with said first deflection speed;

generating said predetermined pattern on the work table with said energy beam spot while deflecting said energy beam spot with a second deflection speed;

detecting second positions of said energy beam spot on said work table created with said second deflection speed; and

comparing said first and second positions, verifying that each one of said first positions deviate less than a predetermined distance from corresponding ones of said second positions.

14. The computer-implemented method according to claim 13, wherein:

the method is further configured for verifying a size of the at least one energy beam spot; and

the method further comprises the steps of, via said at least one control unit;

(a) generating a first energy beam spot from a first energy beam source, the first energy beam spot having a predetermined size and power at a first position on a work piece,

(b) varying at least one of a focus lens setting or an astigmatism lens setting for said first energy beam spot until a maximum intensity of the first energy beam spot is detected,

(c) comparing at least one setting of said focus lens and/or astigmatism lens associated with said detected maximum intensity of the first energy beam spot with corresponding stored settings of said focus lens and/or astigmatism lens associated with said predetermined size and power of the first energy beam spot,

(d) repeating steps a-c for different predetermined beam powers, and

(e) repeating steps a-d for different positions on said work piece, and verifying said first energy beam spot size by verifying that each of said focus lens and/or astigmatism lens settings associated with the detected maximum intensity deviate less than a predetermined value from corresponding stored settings of said focus lens and/or astigmatism lens.

15. The computer-implemented method according to claim 1, wherein:

the method is further configured for verifying a size of the at least one energy beam spot; and

the method further comprises the steps of, via said at least one control unit;

(a) generating a first energy beam spot from a first energy beam source, the first energy beam spot having a predetermined size and power at a first position on a work piece,

(b) varying at least one of a focus lens setting or an astigmatism lens setting for said first energy beam spot until a maximum intensity of the first energy beam spot is detected,

(c) comparing at least one setting of said focus lens and/or astigmatism lens associated with said detected maximum intensity of the first energy beam spot with corresponding stored settings of said focus lens and/or astigmatism lens associated with said predetermined size and power of the first energy beam spot,

(d) repeating step a-c for different predetermined beam powers, and

(e) repeating step a-d for different positions on said work piece, and verifying said first energy beam spot size by verifying that each of said focus lens and/or astigmatism lens settings associated with the maximum intensity deviate less than a predetermined value from corresponding stored settings of said focus lens and/or astigmatism lens.