Abstract: The position of a workpiece delivered into a welding station by a feed mechanism is detected by CCD cameras of position detectors, and a positioning error of the workpiece with respect to a reference position is determined on the basis of the detected position. After training data for welding robots is corrected on the basis of the determined positioning error, scan heads on distal ends of the welding robots are inserted into the workpiece. After the scan heads have been inserted to predetermined positions in the workpiece, only the scan heads are actuated to weld the workpiece at a plurality of locations thereof with a laser beam.

Abstract: A laser beam welding apparatus has a first laser oscillator for applying a laser beam to a right-hand automobile door, a second laser oscillator for applying a laser beam to a left-hand automobile door, and first through fourth laser beam path changing mechanisms for changing the laser beam path of the laser beam from the first laser oscillator in the event of a failure of the second laser oscillator, and changing the laser beam path of the laser beam from the second laser oscillator in the event of a failure of the first laser oscillator. Even when one of the laser beam oscillators fails to operate due to a malfunction, an overall welding line combined with the laser beam welding apparatus does not need to be shut down, and the laser beam welding apparatus can smoothly and efficiently weld the workpieces.

Abstract: After a workpiece introduced into a welding station by a feed mechanism is positioned and fixed in the welding station, the workpiece is welded by laser beams guided by scan heads. Each laser beam is applied from one of the scan heads to a location on the workpiece through a beam path switching mirror of a beam path switcher to weld the location on the workpiece. Thereafter, the beam path switching mirror is retracted to guide the laser beam from another one of the scan heads to another location on the workpiece to weld the other location on the workpiece.