PURPOSE: To provide a joint line detector which is capable of surely identifying the joint line of objects to be welded from the dust and flaws existing on the work surfaces of the objects to be welded and has high reliability.
CONSTITUTION: Illumination devices 6, 7 respectively emit scattered light beams and the joint line 4 of the objects 2, 3 to be welded are respectively illuminated with these beams from different directions. The image of an observation region 11 of the objects 2, 3 to be welded is picked up by an image pickup device 5 and the image information of the common part of the observation region 11 illuminated by the illumination devices 6, 7 is subjected to image processing, by which the joint line 4 is detected. A change in the bright and dark parts of the dust and flaws existing near the joint line 4 generated by a change in the illumination direction varies from the change in the bright and dark parts of the joint line. The information to identify the joint line existing in the common part of the region of the objects 2, 3 to be welded illuminated by the different illumination devices 6, 7 and the dust and flaws increases. As a result, the joint line and the dust and flaws are easily and surely identified.
SUMII YASUHIRO
NAKAOKA SADAAKI
HAMADA YOICHI
