Patent ID: 8487211
Filing Date: 2013-07-16
Classification: B23K

Abstract:
1. A fusion welding method for butt-welding a first member and a second member, comprising the steps of: measuring a width of a gap between the first member and the second member along an extending direction of the gap; and generating a hybrid laser beam by mixing a low-intensity laser beam with a first high-intensity laser beam and a second high-intensity laser beam, the first high-intensity laser beam and the second high-intensity laser beam each having a smaller application area and a higher intensity peak than the low-intensity laser beam, and moving the hybrid laser beam along the gap to apply the low-intensity laser beam, the first high-intensity laser beam and the second high-intensity laser beam to the gap and a periphery of the gap, an area of the first member to which the low-intensity laser beam is applied, and an area of the second member to which the low-intensity laser beam is applied, respectively, in the step of moving the hybrid laser beam along the gap, the fusion welding method comprising the steps of: adjusting an intensity of the low-intensity laser beam to be within a range where a keyhole is not formed in the first member and the second member in the periphery of the gap, depending on a change in the width of the gap; forming a first keyhole in the first member in the periphery of the gap with the first high-intensity laser beam and the low-intensity laser beam to melt a portion facing the gap of the first member via the first keyhole, and forming a second keyhole in the second member in the periphery of the gap with the second high-intensity laser beam and the low-intensity laser beam to melt a portion facing the gap of the second member via the second keyhole; filling the gap with melt obtained by melting the portion facing the gap of the first member and melt obtained by melting the portion facing the gap of the second member, and cooling down a welded part between the first member and the second member with the low-intensity laser beam.