ENERGY BEAM POSITION VERIFICATION

• US 20160202043A1
• Filed: 03/22/2016
• Published: 07/14/2016
• Est. Priority Date: 08/20/2014
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Snis, Anders
• Granted Patent: US 9,664,505 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 method for verifying a position of an energy beam spot, said method comprising the steps of:

providing, via at least one control unit, an energy beam having a first focus in at least two positions on 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, via said at least one control unit, said energy beam having a second focus in said at least two positions on 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, and

comparing, via said at least one control unit, said at least two positions created with said first and second focuses, wherein said position of the energy beam is verified if said at least two positions created with said first focus are deviating less than a predetermined distance from said 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 method according to claim 1, wherein said at least two positions is a regularly 2-dimensional pattern.

3. The method according to claim 1, wherein said at least two positions are provided at identical positions as in a calibration process.

4. The method according to claim 3, wherein said at least two positions are provided at different positions as in a calibration process.

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

6. The method according to claim 1, wherein said worktable is provided with a reference pattern.

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

C.

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

m.

9. The method according to claim 1, further comprising a step of sending out a warning signal if any one of said at least two positions provided with said first focus is deviating more than said predetermined distance from said at least two positions provided with said second focus.

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

11. The method according to claim 4, wherein said deviation in position of said first and second focus is compensated for by altering a setting of a deflection coil.

12. The 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 method according to claim 1, wherein:

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

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

generating a predetermined pattern on a 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 a 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, wherein said deflection speed is verified if each one of said first positions are deviating less than a predetermined distance from corresponding ones of said second positions.

14. The 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 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 max intensity for the first beam spot is detected,

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

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

(e) repeating steps a-d for different positions on said work piece, wherein said first energy beam spot size is verified if each detected settings of said focus lens and/or astigmatism lens are deviating less than a predetermined value from corresponding stored settings of said focus lens and/or astigmatism lens.

15. The 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 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 max intensity for the first beam spot is detected,

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

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

(e) repeating step a-d for different positions on said work piece, wherein said first energy beam spot size is verified if each detected settings of said focus lens and/or astigmatism lens are deviating less than a predetermined value from corresponding stored settings of said focus lens and/or astigmatism lens.

16. A non-transitory computer readable medium having stored thereon a program element configured and arranged when executed on a computer to implement a method for verifying a position of an energy beam spot, said method comprising the steps of:

providing said energy beam having a first focus in at least two positions on said 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 energy beam having a second focus in said at least two positions on said 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, and

comparing, via an executable portion of the program element, said at least two positions created with said first and second focuses, wherein said position of the energy beam is verified if said at least two positions created with said first focus are deviating less than a predetermined distance from said at least two positions created with said second focus.