| 摘要 |
<p>Both a system (1) and method for laser welding the inner surface (20) of a metallic tube (22), which may be a sleeve (19) inside a heat exchanger tube (22) of a nuclear steam generator (23), is disclosed. The system (1) comprises an elongated tubular housing (57) that is insertable within a reinforcing sleeve (19) disposed within a heat exchanger tube (22), a laser unit (11) for generating a beam of light, a fiber optical conduit (10) for conducting light from the laser unit (11) through the interior of the tubular housing (57), a beam deflection assembly (5) including a mirror (71) canted at an angle of 45 DEG that is rotatably mounted on the distal end (59) of the housing (57) and optically connected to the fiber optical cable (10), and a remotely powered rotary drive assembly (5) for rotating the beam deflection assembly (5) to direct laser light around the inner surface (20) of the tube (22) that includes a motion transducer (77, 89) for converting linear to rotary motion. The motion transducer (77, 89) includes a tubular driven member (77) concentrically disposed within said housing (57) and connected to the beam deflection assembly (5), and a tubular drive member (89) concentrically disposed within the driven member (77) and having a spiral groove (93) around its outer diameter that meshes with a follower ball (87) connected to the inner diameter of the driven tube (77), such that the driven member (77) rotates whenever the drive member (89) is slidably pulled along the longitudinal axis of the housing (57). The linear-to-rotational motion transducer (77, 89) obviates the need for miniaturized electrical or pneumatic motors, which in turn allows the outer diameter of the housing (57) of the system (1) to be made small enough to service small-diametered heat exchanger tubes (22). <IMAGE></p> |
