Laser processing machine, in particular laser cutting machine, and method for centering a laser beam, in particular a focused laser beam

• US 9,296,067 B2
• Filed: 07/26/2013
• Issued: 03/29/2016
• Est. Priority Date: 01/27/2011
• Status: Active Grant

• Current Assignee: Bystronic Laser AG (Invico Asset Management AG)
• Original Assignee: Bystronic Laser AG (Invico Asset Management AG)
• Inventors: Cathry, Daniel, Beutler, Beat, Rauschenbach, Sven
• Primary Examiner(s): Heinrich, Samuel M
• Application Number:
  US13/952,571
• Publication Number:
  US 20140014632A1
• Time in Patent Office: 977 Days
• Field of Search: 219/121.6, 219/121.62, 219/121.67, 219/121.72, 219/121.78, 21912183-12185
• US Class Current: 1/1
• 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 26/042 Automatically aligning the laser beam
• CPC Class Codes: B23K 26/043 along the beam path, i.e. alignment of laser beam axis relative to laser beam apparatus
• CPC Class Codes: B23K 26/14 using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor B23K26/12 takes precedence
• CPC Class Codes: B23K 26/38 by boring or cutting

Abstract

Laser processing machines (LM), in particular laser cutting machines with long-wave laser radiation (in particular CO₂ laser), including at least one laser processing head (1), having interior (2) and nozzle (3) with nozzle orifice (4) for allowing a primary beam (5), in particular a focused laser working beam, to pass through and onto a work piece (6) and to align a gas current enveloping the beam, and an alignment device (15) with several sensors (13) for centering the primary beam (5), in particular a focused laser working beam, and the nozzle orifice (4) relative to each other. At least one conversion unit (9), in particular a conversion edge, is provided in the area of the nozzle orifice (4) for converting the primary beam (5) contacting it or impacting on it into one or more secondary electromagnetic heat beams (10) along at least one propagation direction (10A) in direction of the sensors (13). The sensors (13) are configured as radiation sensors and arranged in the interior (2) of the laser processing head (1) or the nozzle (3).

Claims

1. A laser processing machine comprising:

a laser processing head, said laser processing head having an interior, said interior having an interior wall, said interior wall being disposed about a central axis;

a nozzle associated with said laser processing head, said nozzle having a nozzle orifice for a primary focused laser beam;

a beam centering arrangement including a plurality of sensors;

a conversion edge provided in the area of said nozzle orifice to convert at incidence the primary laser beam into at least one secondary electromagnetic heat beam respectively directed along at least one propagation direction towards said plurality of sensors; and

,

said plurality of sensors each having at least one respective glass pane provided with a reflective coating reflective relative to the primary laser beam, each said respective glass pane converting long-wave IR of the primary laser beam into short-wave IR of the secondary electromagnetic heat beam, said plurality of sensors being NIR heat radiation sensors including InGaAs diodes and being arranged to view through respective openings in said interior wall of said laser processing head.

2. A laser processing machine as claimed in claim 1, further comprising:

said plurality of sensors being evenly distributed around a circumference of said interior wall; and

,

each of said respective view openings has a respective center, said plurality of respective view opening centers being arranged in a plane normal to said central axis.

3. A laser processing machine as claimed in claim 1, further comprising:

at least one heat beam reflector arranged between said plurality of sensors and said conversion edge, said heat beam reflector redirecting the at least one secondary electromagnetic heat beam from its at least one propagation direction towards at least one of said plurality of sensors.

4. A laser processing machine as claimed in claim 1, further comprising:

said conversion edge in cross-section forms an angle of inclination in the range of 4°

to 7°

relative to a plane normal to said central axis.

5. A laser processing machine as claimed in claim 1, further comprising:

said conversion edge is located on an inner shell surface of said nozzle.

6. A laser processing machine as claimed in claim 1, further comprising:

said conversion edge includes plural non-contiguous conversion segments.

7. A laser processing machine as claimed in claim 1, further comprising:

said conversion edge has at least one of a (1) wear resistant coating, or, (2) a conversion-accelerating coating.

8. A laser processing machine as claimed in claim 1, further comprising:

each of said plurality of NIR heat radiation sensors has a respective holder that holds it and its at least one respective glass pane, each of said plurality of holders being fixed in a respective recess in said laser processing head.

9. A process for centering a primary focused laser beam comprising the steps of:

defining a X-Y coordinate plane normal to a nozzle axis;

providing a conversion edge in the interior of a nozzle;

converting long-wave IR of a primary focused laser beam to generate short-wave NIR of a secondary heat beam;

displacing the primary focused laser beam on the X-Y coordinate plane and transversely relative to a nozzle orifice, until the primary focused laser beam establishes incidence on the conversion edge;

radiating from the conversion edge, along at least one propagation direction, secondary heat radiation in the NIR range;

measuring values of the propagated heat radiation in the NIR range with heat radiation sensors;

assigning each measured value of heat radiation to associated X-Y coordinates of the nozzle axis and the primary focused laser beam;

calculating a position of a center of the nozzle orifice relative to the position of the primary focused laser beam by employing corresponding measured values obtained after plural repetitions of said step of displacing the primary focused laser beam; and

,

based on said step of calculating, effecting an adjusting of the center of the nozzle orifice relative to the primary focused laser beam to center the laser beam.

10. The process for centering a primary focused laser beam as claimed in claim 9, wherein:

said step of displacing the primary focused laser beam on the X-Y coordinate plane and transversely relative to a nozzle orifice until the primary focused laser beam establishes incidence on the conversion edge, is performed in three or more directions on the X-Y coordinate plane.

11. A process for centering a primary focused laser beam as claimed in claim 9, further comprising the steps of:

determining heat beam maxima and an intermediate minimum for the heat beam by performing said step of displacing the primary focused laser beam on the X-Y coordinate plane and transversely relative to a nozzle orifice, until the primary focused laser beam establishes incidence on the conversion edge, from X_min to X_max and also from Y_min to Y_max; and

,

centering by adjusting the X and Y coordinates of the center of the nozzle orifice to the X and Y coordinates of the heat beam minimum.

12. A process for centering a primary focused laser beam as claimed in claim 9, further comprising the step of:

substituting the primary focused laser beam with a low-power directional beam.

13. The process for centering a primary focused laser beam as claimed in claim 9, wherein:

said step of converting long-wave IR of a primary focused laser beam to generate short-wave NIR of a secondary heat beam includes converting CO₂ laser working beam containing wavelength of 10.6 μ

m, into secondary heat beam containing wavelengths of 1.0-2.2 μ

m and visible to InGaAs diode heat radiation sensors.

14. The process for centering a primary focused laser beam as claimed in claim 9, wherein:

said step of converting long-wave IR of a primary focused laser beam to generate short-wave NIR of a secondary heat beam is effected at least in part by providing a coated glass pane in a line-of-sight of a heat radiation sensor.

15. A laser processing machine comprising:

a laser processing head, said laser processing head having an interior, said interior having an interior wall, said interior wall being disposed about a central axis;

a nozzle associated with said laser processing head, said nozzle having a nozzle orifice for a primary focused laser beam;

a beam centering arrangement including a plurality of radiation sensors;

a conversion edge provided in the area of said nozzle orifice to convert at incidence the primary laser beam into at least one secondary electromagnetic heat beam respectively directed along at least one propagation direction towards said plurality of sensors; and

,

said plurality of sensors being arranged to view through respective openings in said interior wall of said laser processing head.

16. A laser processing machine as claimed in claim 15, further comprising:

said plurality of sensors being evenly distributed around a circumference of said interior wall; and

,

each of said respective view openings has a respective center, said plurality of respective view opening centers being arranged in a plane normal to said central axis.

17. A laser processing machine as claimed in claim 15, further comprising:

at least one heat beam reflector arranged between said plurality of sensors and said conversion edge, said heat beam reflector redirecting the at least one secondary electromagnetic heat beam from its at least one propagation direction towards at least one of said plurality of sensors.

18. A laser processing machine as claimed in claim 15, further comprising:

said conversion edge is located on an inner shell surface of said nozzle; and

,

said conversion edge in cross-section forms an angle of inclination in the range of 4°

to 7°

relative to a plane normal to said central axis.

19. A laser processing machine as claimed in claim 15, further comprising:

said conversion edge includes plural non-contiguous conversion segments.

20. A laser processing machine as claimed in claim 15, further comprising:

said conversion edge has at least one of a (1) wear resistant coating, or, (2) a conversion-accelerating coating.