Control system for depositing powder to a molten puddle

• US 6,605,795 B1
• Filed: 11/06/2000
• Issued: 08/12/2003
• Est. Priority Date: 11/04/1999
• Status: Expired due to Term

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Inventors: Cleveland, Bradley A., Fullen, Mark S., Arcella, Frank G.
• Primary Examiner(s): ELVE, MARIA ALEXANDRA
• Application Number:
  US09/707,186
• Time in Patent Office: 1,009 Days
• Field of Search: 219/121.63, 219/121.64, 219/121, 219/65, 219/121.66, 219/121.85
• US Class Current: 219/121.63
• CPC Class Codes: B22F 10/25 Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
• CPC Class Codes: B22F 10/30 Process control
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 12/33 translatory in the deposition plane
• CPC Class Codes: B22F 12/46 with translatory movement
• CPC Class Codes: B22F 12/53 Nozzles
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• 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 26/0884 in at least in three axial directions, e.g. manipulators, robots
• CPC Class Codes: B23K 26/144 the fluid stream containing particles, e.g. powder
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B23K 35/0244 Powders, particles or spheres; Preforms made therefrom
• CPC Class Codes: B23K 35/0255 for use in welding B23K35/0205 takes precedence
• CPC Class Codes: B29C 64/153 using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: Y02P 10/25 Process efficiency

Abstract

An imaging system for controlling powder aiming in a molten puddle. In the imaging system of the present invention, an image processor extracts a first image of the molten puddle and a second image of a powder envelope from a composite image of the weld area. The first and second processed images provide feedback for process control.

Claims

1. A material deposition system comprising:

an energy source orientated to form a molten puddle on a workpiece;

a nozzle coupleable to a source of flowable weld material and having a discharge opening orientated to deposit the flowable weld material to the molten puddle;

an imager orientated to capture an image of a weld area including the molten puddle and the deposited flowable weld material; and

an image processor coupled to the imager including;

first image processing to extract a profile of the molten puddle from the image of the weld area; and

second image processing to extract a profile of the deposited weld material from the image of the weld area.

2. The material deposition system of claim 1 wherein the first image processing calculates profile coordinates for the molten puddle.

3. The material deposition system of claim 2 wherein the second image processing calculates profile coordinates for the deposited weld material.

4. The material deposition system of claim 3 wherein the image processor calculates a bias based upon the profile of the weld material relative to the profile of the molten puddle.

5. The material deposition system of claim 4 and further comprising a control processor configured to calculate a control command based upon the calculated bias.

6. The material deposition system of claim 5 wherein the control command adjusts a standoff operating parameter of the energy source or the nozzle relative to the workpiece.

7. The material deposition system of claim 5 wherein the control command adjusts feed rate or dispersement parameters of the weld material.

8. The material deposition system of claim 1 wherein the energy source is a laser.

9. A material deposition system comprising:

a laser to form a molten puddle on a weld area of a workpiece;

an imager orientated to capture an image of the weld area on the workpiece; and

a processor coupled to the imager and configured to process the image of the weld area to isolate a profile of the molten puddle and calculate a scaled position of the molten puddle relative to a datum.

10. The material deposition system of claim 9 wherein the scaled position of the molten puddle relative to the datum is used for standoff control.

11. The material deposition system of claim 9 wherein the processor calculates a scaled orientation of the molten puddle relative to the datum to control orientation of the laser.

12. The material deposition system of claim 9 wherein the processor calculates a stand-off bias between the scaled position of the molten puddle and the datum.

13. The material deposition system of claim 12 wherein an offset command is calculated based upon the calculated standoff bias to adjust standoff.

14. The material deposition system of claim 9 wherein the processor calculates a scaled standoff and orientation of the molten puddle relative to the datum.

15. The material deposition system of claim 11 wherein the processor calculates a bias based the scaled orientation of the molten puddle relative to the datum.

16. The material deposition system of claim 15 wherein an offset command is calculated based upon the calculated bias to adjust alignment of the laser.

17. A method for welding control comprising steps of:

heating a workpiece to form a molten puddle in a welding area;

depositing a weld material to the molten puddle in the welding area;

imaging the welding area; and

processing an image of the welding area to extract a profile of the molten puddle and a profile of the deposited weld material.

25. The method of claim 17 and further comprising the step of:

calculating a bias between the profile of the deposited weld material relative to the profile of the molten puddle.

26. An article formed using the method of claim 17.

18. A method of welding control comprising steps of:

heating a workpiece to form a molten puddle in a welding area;

depositing a weld material to the molten puddle;

imaging the welding area;

processing an image of the welding area to extract a profile of the molten puddle; and

calculating a bias of a position of the molten puddle relative to a reference datum.

19. The method of claim 18 and further comprising a step of:

adjusting operating parameters relative to the calculated bias to adjust the position of the molten puddle relative to the reference datum.

20. The method of claim 19 wherein the step of adjusting the operating parameters includes adjusting at least one of a laser position for heating the workpiece, nozzle position for depositing the weld material, or feed parameters of the weld material.

27. An article formed using the method of claim 18.

21. An imaging system for welding applications comprising:

an imager;

an image processor to extract a molten profile from an image and calculate a scaled position of the molten profile relative to a datum.

22. The imager of claim 21 wherein the image processor calculates a bias between the scaled position of the molten profile and the datum.

23. The image of claim 21 wherein the processor calculates a standoff bias and an orientation bias relative to the datum.

24. An imaging system for welding applications comprising:

an imager and an image processor configured to extract a profile of a molten puddle from an image and a profile of deposited weld material from the image and calculate a bias between the profile of the deposited weld material and the profile of the molten puddle.