| 摘要 |
A method of welding using a high energy density radiation beam such as an electron beam or preferably a laser beam to weld a pair of sheets using an oblong focused beam spot for reducing the power density of the oblong beam spot to maximize welding speed while minimizing welding defects. The high energy density radiation beam source has a power of at least one kilowatt for achieving Keyhole welding, and a beam delivery system capable of focusing the beam into an oblong spot shape, such as a generally rectangular focused beam spot shape, and directing the beam spot onto at least one of the sheets to weld the sheets. During welding, the beam is focused into an oblong focused beam spot and trained on at least one of the sheets to weld them with the longitudinal axis of the beam spot preferably oriented generally tangent to the weld line, generally parallel to the weld direction, or acutely angled relative to the tangent to the welding direction. Preferably, if a laser is used, it is a laser emitting a continuous wave beam, a pulsed laser operating at a duty cycle of at least 50% such that it substantially performs as a laser emitting a continuous wave beam, or a laser in rippled or modulated mode having a continuous beam component with an average output power of at least 80% of the peak power of the laser so that it substantially performs as a continuous wave laser beam. |
