Method and apparatus for monitoring laser weld quality via plasma size measurements
US5961859A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 23, 1997 |
| Grant date | Oct 5, 1999 |
| Priority date | — |
| Expiry date | Oct 23, 2017 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB23K26/032
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A method and apparatus for monitoring the quality of a laser process such as a welding process comprises monitoring the light emitted from the weld plasma above the surface of the workpiece being irradiated by the laser beam. The size of the plasma is determined from the light emission and compared to a predetermined value of the size as determined under process and workpiece conditions that produce welds of acceptable quality. Variations of the monitored plasma size greater than a preselected value can represent unacceptable welds. Such variations can be caused by changes in the laser beam power, the workpiece speed, laser focusing problems, insufficient shield gas flow, workpiece deformation and weld contamination. The process monitors the light emission from a selected range of wavelengths that correspond to the major emission peaks of the light spectrum. The process enables in-process control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.