To provide a weld crack detection method and its device, capable of easily and certainly detecting weld cracks that occur in a welded bead.
In this method, the object being a weld bead 4 that is formed by laser welding of overlapping parts of flanges 1a and 2a of sheet steels 1 and 2, the surrounding heat affected zone 5 is focused and imaged by a CCD camera 11, and the image data is sent to an image data processing unit 12. The image data processing unit 12 determines the width of the heat affected zone 5 from the boundary position between the heat affected zone 5 and the surface of a parent material and sends the result to a quality determination unit 13. Since the width of the heat affected zone 5 is smaller when a weld crack occurs in the weld bead 5, the quality determining unit 13 compares it with a predetermined threshold, based on the width of a heat-affected zone when there is no crack, and determines the presence or the absence of weld cracks, and displays the result on a display unit 14.
FURUKAWA MASASHI
KOYAKE KOJI
Miyazaki Yoshio
Kaoru Onozuka
Akio Tagami
High Masahiro
Toshio Nakamura