Detecting an incomplete cutting action

Patent metadata

Field	Value
Publication number	US-9457427-B2
Application number	US-201414286014-A
Country	US
Kind code	B2
Filing date	May 23, 2014
Priority date	May 23, 2013
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

Methods, devices and systems for detecting an incomplete cutting action when cutting a workpiece with a high-energy beam are disclosed. In one aspect, a method includes taking an image of a region of the workpiece to be monitored, the region including an interaction region of the high-energy beam with the workpiece, evaluating the image taken in order to detect pooled slag at an end of the interaction region opposite a cutting front, and detecting whether a related cutting action is incomplete based on an occurrence of detection of pooled slag.

First claim

What is claimed is:

1. A method of detecting an incomplete cutting action when cutting a workpiece with a high-energy beam, the method comprising:
obtaining an image of a region of the workpiece as the high-energy beam cuts the workpiece, the region including an interaction region of the high-energy beam with the workpiece;
evaluating the image to detect a presence of slag at a receding end of the interaction region that is opposite to an advancing front of the interaction region, wherein the slag is discharged in an upward direction from a cutting gap in the workpiece towards an upper side of the workpiece on which the high-energy beam is incident; and
determining that the high-energy beam has not completely cut through the workpiece from the upper side to a lower side of the workpiece based on the detection of the presence of the slag.

2. The method of claim 1 , wherein obtaining the image comprises obtaining a thermal image of the interaction region.

3. The method of claim 1 , wherein obtaining the image comprises obtaining an externally illuminated image of the interaction region.

4. The method of claim 1 , wherein obtaining the image comprises obtaining the image of the interaction region coaxially relative to a beam axis of the high-energy beam.

5. The method of claim 4 , wherein obtaining the image comprises detecting process radiation that has been reflected from the workpiece and that has passed through a nozzle opening of a processing nozzle through which the high-energy beam also passes.

6. The method of claim 5 , wherein evaluating the image comprises evaluating a portion of the image that is adjacent to an edge of an inner contour of the nozzle opening.

7. The method of claim 1 , wherein evaluating the image comprises detecting the presence of the slag based on a local intensity minimum occurring in the image at the receding end of the interaction region that is opposite to the advancing front of the interaction region.

8. The method of claim 1 , wherein evaluating the image comprises detecting the presence of the slag based on a change of a geometry of the interaction region at the receding end thereof opposite the cutting front.

9. The method of claim 1 , further comprising: in response to determining that the high-energy beam has not completely cut through the workpiece, modifying a power of the high-energy beam, altering a focal point of a laser processing head, or altering a spacing between the laser processing head and the workpiece so that the high-energy beam cuts through the workpiece.

10. The method of claim 1 , further comprising: in response to determining that the high-energy beam has not completely cut through the workpiece, interrupting cutting of the workpiece.

11. A device for detecting an incomplete cutting action when cutting a workpiece with a high-energy beam, the device comprising:
an image detector configured to obtain an image of a region of the workpiece as the high-energy beam cuts the workpiece, the region including an interaction region of the high-energy beam with the workpiece during the cutting of the workpiece; and
an image processor configured to evaluate the image to detect a presence of slag at a receding end of the interaction region that is opposite to an advancing front of the interaction region, wherein the slag is discharged in an upward direction from a cutting gap in the workpiece towards an upper side of the workpiece on which the high-energy beam is incident, and
to determine, based on detecting the presence of slag, that the high-energy beam has not completely cut through the workpiece from the upper side of the workpiece to a lower side of the workpiece.

12. The device of claim 11 , wherein the image detector is configured to obtain a thermal image of the interaction region.

13. The device of claim 11 , wherein the image detector is configured to obtain an externally illuminated image of the interaction region.

14. The device of claim 11 , wherein the image detector is configured to obtain the image of the region coaxially relative to a beam axis of the high-energy beam.

15. The device of claim 14 , wherein the image detector is configured to obtain the image of the interaction region from process radiation that has been reflected from the workpiece through a nozzle opening of a processing nozzle through which the high-energy beam also passes.

16. The device of claim 15 , wherein the image processor is configured to evaluate a portion of the image that is adjacent to an edge of an inner contour of the nozzle opening.

17. The device of claim 11 , wherein the image processor is configured to detect the presence of the slag based on a local intensity minimum occurring in the image at the receding end of the interaction region that is opposite to the advancing front of the interaction region.

18. The device of claim 11 , wherein the image processor is configured to detect the presence of the slag based on a change of a geometry of the interaction region at the receding end thereof opposite the cutting front.

19. A cutting system comprising:
a beam source configured to generate a high-energy beam;
a processing head arranged to guide the high-energy beam onto a workpiece; and
a cut quality evaluator for detecting that the high-energy beam has not completely cut through the workpiece from an upper side of the workpiece on which the high-energy beam is incident to a lower side of the workpiece, the evaluator comprising:
an image detector configured to obtain an image of an interaction region of the high-energy beam with the workpiece during cutting of the workpiece with the high-energy beam; and
an image processor configured to evaluate the image to thereby detect a presence of slag at a receding end of the interaction region that is opposite an advancing front of the interaction region, wherein the slag is discharged in an upward direction from a cutting gap in the workpiece towards the upper side of the workpiece, and to determine, based on detecting the presence of the slag, that the high-energy beam has not completely cut through the workpiece from the upper side of the workpiece to the lower side of the workpiece.

20. The cutting system of claim 19 , further comprising a cutting controller coupled to the cut quality evaluator, wherein the cutting controller is configured to, in response to receiving an indication from the cut quality evaluator that the high-energy beam is not completely cutting through the workpiece, modifying a power of the high-energy beam, altering a focal point of a laser processing head, or altering a spacing between the laser processing head and the workpiece so that the high-energy beam cuts through the workpiece.

Assignees

• Trumpf Werkzeugmaschinen Gmbh Co Kg

Inventors

• Hesse Tim
• Schindhelm David
• Regaard Boris

Classifications

• B23K10/006

  Control circuits therefor · CPC title

• B23K10/00

  Welding or cutting by means of a plasma · CPC title

• B23K26/38

  by boring or cutting · CPC title

• B23K31/125

  Weld quality monitoring · CPC title

• B23K26/702

  Auxiliary equipment · CPC title