High Power YAG Laser Application for Heavy Component Welding and Cutting.

Abstract

We initially applied the 6kW to 10kW YAG lasers in order to weld and cut heavy components. We used optical fiber beam guide systems whose core diameters are 0.6mm to 0.8mm in length and having a standard length of 200m. Using the above systems we can realize a penetration depth of 15mm to 20mm per pass. Multi-pass welding is utilized for thicker plates. Data is also given for nuclear power plant dismantling in which 100mm thick plates are cut. These systems were used in conjunction with CCD camera image processing which monitored the systems in process. Monitoring fibers were placed co-axial to the YAG optical lens system during the in-process monitoring by means of a monitoring fiber. Light intensity emanating from the cutting or welding area was measured during the monitoring. Furthermore, we have developed a new hybrid welding system using TIG electrode located in the center of the lens. This ensures that high power can be maintained. This hybrid welding system (TIG-YAG) aims to decrease welding groove allowances and improve the quality of welding. It also enables arc and laser welding to be carried out simultaneouslyby positioning the TIG electrode in the center of the YAG optical lens. Through these techniques we have applied a 7kW class YAG laser to weld nuclear power plant components.