Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1998-04-08
2001-09-18
Couso, Jose L. (Department: 2621)
Image analysis
Applications
Manufacturing or product inspection
C219S121850
Reexamination Certificate
active
06292584
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the use of coherent energy processes for high powered pulse lasers, in the shock processing of solid materials, and more particularly, to methods and apparatuses to accurately control the laser peening process in a production environment.
2. Description of the Related Art
Known methods of shock processing solid materials and particularly laser shock processing solid materials using coherent energy, as from a laser, orient the laser beam normal, i.e., perpendicular, to the workpiece.
Particular constraints of laser processing are formed based on the shape of material or other geometric factors such as, attempting to laser shock harden integrally bladed rotors (IBRs), blind bores, slots, or dove-tailed sections. The laser beam utilized may not have a direct line-on-sight access to the area to be shock processed. Laser shock processing techniques and equipment can be found in U.S. Pat. No. 5,131,957 to Epstein.
Production problems occur with the placement and location of the workpiece to be processed. Particular pieces of information such as knowing the present and actual location of the workpiece, along with determining whether the laser peening system has hit the workpiece where the control program has instructed the laser to do so are important to part quality and reproducibility of results.
What is needed in the art is an automatic system for determining and controlling laser peening process variables.
SUMMARY OF THE INVENTION
According to the present invention, the laser peening system utilizes a computerized system for identifying that a workpiece is in a correct placement attitude, and that the laser peening operation was conducted at a correct location on the workpiece.
The invention, in one form thereof, is that of a tool fixture, to hold the workpiece to be worked (i.e., laser peened). Based upon particular physical characteristics of the tool fixture, the present invention and system can readily identify the location of the fixture based upon reference or locator spots thereon.
A laser processing environment may contain conditions where visibility, at least to the visible light spectrum, may be diminished. The system can also utilize and target areas on the fixture by reference spots, reflectors, LEDs, or other types of indicators, for location within the process environment.
Additionally, positioning encoders may be affixed with the fixture movement means to identify the location of the fixture and workpiece at all times. Such position encoders would actually be just initial or absolute reference markers, since there would still be a need for measuring a reference mark for error trapping and system feedback control.
Another feature of the present invention is that the system can identify, via a number of different means, the focus or angle of the beam shot, and triangulate same from distance calculation based upon the tool fixture reference spots. Such identification can determine whether or not the laser beam moves out of a particular range, thereby causing the laser peening system to stop processing and alert the operator, or to utilize such data to automatically re-align the workpiece on the laser beam. In the most preferred case, the absolute location of the laser spot shall stay substantially immovable, while the tool fixture and workpiece are moved to reposition the laser spot on the workpiece.
Yet another feature of the present invention is that of using a video camera to capture the location of the workpiece and fixture. Utilizing image-grabbing software, along with filters to prevent burn out of the video camera, the system may measure the location of the tool fixture at one or more different frequencies to store and analyze data regarding the laser peened spot or beam reflection. Additionally, the imaging system of the present invention utilizing a video camera, may be able to detect whether or not a sufficient plasma has formed during the laser peening operation to sufficiently work the workpiece. Additionally, the video camera can be used to detect whether or not the transparent overlay utilized in laser peening operations system has been properly created.
Other variables of the laser peening system may be determined by the inventional imaging system such as, whether or not there is any transparent or opaque overlay applied to the workpiece, and determining whether or not the proper laser spot size was applied to the workpiece. Of course, other variables may be detected and utilized such as, whether or not the opaque overlay was correctly placed and are of the correct thickness.
The video imaging aspect of the present invention, utilizes elements to ensure capture of the laser beam to prevent ghosts and other spurious signals in the digitized data stream. In one aspect of the invention, the digital camera is synchronized to the frame rate and/or the speed of the laser beam. If the camera frame rate is not synchronized to the laser, the camera may observe a portion of the laser spot on more than one frame.
The invention, in one form thereof, is an image processing system for monitoring a laser peening process. The processing system includes a laser peening system having a workpiece positioner and a system controller, a video camera for forming an electronic image of at least a portion of the workpiece, and an image processing computer connected to the video camera and the laser peening controller, the image processing computer including a program to determine a position of the workpiece.
The invention, in another form thereof, is an image processing system comprising a laser peening system for creating a laser spot on the workpiece. The laser peening system has both a workpiece positioner and a system controller. A video camera is included for forming an electronic image of at least a portion of the workpiece. An image processing computer is connected to the video camera and the laser peening controller, image processing computer including a program to determine the laser spot size on the workpiece during laser peening.
The invention, in yet another form thereof, comprises a laser peening system having both a workpiece positioner and a system controller, a video camera for forming an electronic image of at least a portion of the workpiece, and an image processing computer connected to the video camera and the laser peening controller, the image processing computer including a program to determine the position of the laser spot on the workpiece during laser peening.
The invention, in still another form thereof, is an image processing system for monitoring a laser peening process utilizing overlays. The image processing system includes a laser peening system having both a workpiece positioner and a system controller, along with a video camera for forming an electronic image of at least a portion of the workpiece. An image processing computer connected to the video camera and the laser peening controller includes a program to determine if one of the laser peening process overlays is applied correctly to the workpiece during laser peening.
The invention, in another form thereof, is a method of controlling a laser peening system utilizing dual-sided processing. The method comprises the steps of applying a laser beam to opposite sides of a workpiece, determining the size of the laser spots on each side of the workpiece via an image processing system, and adjusting at least one of the laser spot sizes to then create a substantially equal sized laser spot on each side of the workpiece.
In still another form, the invention includes a method of controlling laser peening system utilizing dual-sided processing. The method comprises the steps of applying a laser beam to opposite sides of a workpiece, determining the position of the laser spots on each side of the workpiece via an image processing system, and adjusting at least one of the laser spot positions to is provide laser spots on opposite sides of the workpiece which are substantially concentric with each other along a line th
Clauer Allan H.
Dulaney Jeffrey L.
O'Loughlin Mark E.
Couso Jose L.
Dang Duy M.
Knuth Randall J.
LSP Technologies Inc.
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