SLEEVE WELDING METHOD AND DEVICE INTO STEAM GENERATOR TUBE

摘要

A laser welding head for welding a sleeve within a tube by fusing the interface between the sleeve and tube with a laser beam. The laser welding head has a cylindrical housing adapted to be inserted inside of the sleeve, a focusing lens for focusing a laser beam transmitted through the housing, and a welding mirror for directing the focused beam out of the housing and into contact with the sleeve. The welding mirror is maintained a predetermined distance from the inside surface of the sleeve and a motor and drive assembly are used to rotate the welding head within the sleeve. Shield gas is supplied to the welding head and passes about the periphery of the focusing lens for cooling the focusing lens and the welding mirror before being discharged into contact with the weld area. A recessed aperture is provided within the discharge outlet to prevent molten material from the weld site from splattering into the housing and onto the mirror or lens. Multiple pass welds are preferred for attaching each end of the sleeve to the tube with the preferred weld paths being either multiple discrete weld paths or continuous overlapping helical weld paths at each end of the sleeve.