METHOD FOR DETECTING DISPLACEMENT OF LASER IRRADIATION POSITION IN LASER-WELDED STEEL PIPE, METHOD FOR MANUFACTURING STEEL PIPE, DEVICE FOR DETECTING DISPLACEMENT OF LASER IRRADIATION POSITION, DEVICE FOR LASER-WELDING STEEL PIPE, AND DEVICE FOR MANUFACTURING STEEL PIPE

摘要

A method for detecting displacement of a laser irradiation position in a laser-welded steel pipe, in which: a camera (11) simultaneously captures an image, in the same direction as the laser light (3) irradiation direction, of a region including a laser irradiation position (4) and a groove section (5) at which both edges of a steel strip (1) are set at least a prescribed distance from each other so as to not close; and an image processing device (12) detects the laser irradiation position (4) and an abutting position (2) from the captured image and calculates the positional relationship between the detected laser irradiation position (4) and abutting position (2). This makes it possible to prevent the laser irradiation position (4) from being displaced from the abutting position (2), and improve the yield of laser-welded steel pipes.