Stereovision guided laser drilling system

• US 6,977,356 B2
• Filed: 09/30/2003
• Issued: 12/20/2005
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Vaidyanathan, Janakiraman, Pietrzak, Kenneth
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US10/674,997
• Publication Number:
  US 20050067394A1
• Time in Patent Office: 812 Days
• Field of Search: 219/121.7, 219/121.71, 219/121.83, 348/187, 382/141, 382/106, 700/166, 356/3.13, 356/12
• US Class Current: 219/121.71
• 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 26/382 by boring
• CPC Class Codes: B23K 26/389 of fluid openings, e.g. nozzles, jets laser machining of inkjet nozzles B41J2/1634
• CPC Class Codes: G05B 2219/37555 Camera detects orientation, position workpiece, points of workpiece
• CPC Class Codes: G05B 2219/45139 Laser drilling
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration

Abstract

A method for assisting the laser drilling of a hole in a part comprises the steps of providing a camera mounted to the laser, providing a target hole at a first position, capturing a first image of the target hole at the first position with the camera, moving the target hole to a second position and capturing a second image of the target hole, and computing a drilling location of the target hole from the first image and the second image, said computed drilling location used to laser drill the target hole.

Claims

1. A method for assisting the laser drilling of a hole in a part, comprising the steps of:

providing a camera;

providing a target hole at a first position;

capturing a first image of said target hole at said first position with said camera;

moving said target hole to a second position and capturing a second image of said target hole;

computing a drilling location of said target hole from said first image and said second image, said computed drilling location used to drill said target hole; and

wherein computing said drilling location of said target hole comprises using image processing software to locate an actual target hole location, and computing an offset between said actual target hole location and a nominal position.

2. The method of claim 1 comprising the additional step of calibrating said laser.

3. The method of claim 2 comprising the additional step of calibrating said camera.

4. The method of claim 1 wherein providing said target hole comprises providing a part having at least one said target hole.

5. The method of claim 4 wherein providing said target hole comprises providing a turbine blade having at least one said target hole.

6. A method for assisting the laser drilling of a hole in a part, comprising the steps of:

providing a camera;

providing a target hole at a first position;

capturing a first image of said target hole at said first position with said camera;

moving said target hole to a second position and capturing a second image of said target hole;

computing a drilling location of said target hole from said first image and said second image, said computed drilling location used to laser drill said target hole;

calibrating said laser; and

wherein calibrating said laser comprises the steps of;

providing a calibration block having a pinhole;

aligning a laser beam with said pinhole; and

setting a home position of said laser.

7. A method for assisting the laser drilling of a hole in a part, comprising the steps of:

providing a camera;

providing a target hole at a first position;

capturing a first image of said target hole at said first position with said camera;

moving said target hole to a second position and capturing a second image of said target hole;

computing a drilling location of said target hole from said first image and said second image, said computed drilling location used to laser drill said target hole;

calibrating said laser;

calibrating said camera; and

wherein calibrating said camera comprising the steps of;

providing a calibration block;

mounting a calibration target on said calibration block;

imaging said calibration target at a plurality of positions along a z-axis with said camera from said first position and said second position;

computing a 3D-to-2D mapping from said imaged calibration target; and

storing said 3D-to-2D mapping on a storage medium.

8. A method for assisting the laser drilling of a hole in a part, comprising the steps of:

providing a camera;

providing a target hole at a first position;

capturing a first image of said target hole at said first position with said camera;

moving said target hole to a second position and capturing a second image of said target hole;

computing a drilling location of said target hole from said first image and said second image, said computed drilling location used to laser drill said target hole; and

further comprising the additional step of retrieving a nominal position of said target hole from a storage medium, and moving said target hole to said nominal position.

9. An apparatus for laser drilling a hole in a part, comprising:

a laser;

a camera mounted to said laser for capturing a first image of a target hole on a part at a first position and a second image of said target hole at a second position;

means for computing a drilling location of said target hole from said first image and said second image; and

a means for identifying and extracting a nominal position of said target hole.

10. An apparatus for laser drilling a hole in a part, comprising:

a laser;

a camera mounted to said laser for capturing a first image of a target hole on a part at a first position and a second image of said target hole at a second position;

means for computing a drilling location of said target hole from said first image and said second image; and

a calibration block having a pinhole for determining a home position of said laser.

11. The apparatus of claim 10 wherein said target hole is located in a turbine blade.