To automatically calculate the off-seam quantity of a two side butt welding part by removing by grinding the reinforcement of the weld bead from an end part by the prescribed length, and extracting the toe line of the weld bead from the radiographic image including the reinforcement ground part.
The reinforcement of a bead 3 on the inner surface side of a tubular end part of a welded tube 1p is removed by grinding from a tube end by the prescribed length. The radiographic image of a part 9 to be inspected is taken into an image processing computer 15 as the digital image through an image processor 11 and an analog-digital converter 14, and formed as an original image. The lightness of the original image is normalized by the image processor 15, and the noise is removed to perform the binarized image processing. Presence/absence of a boundary part between a reinforcement ground part and a non-ground part is detected, and the center line of the reinforcement of the weld bead which is not ground yet is extracted. After the positional relationship of the toe line is determined, the off-seam quantity is calculated, and compared with the off-seam quantity which is statistically processed in advance to judge acceptance/rejection of the welding quality.
KAWANO SEISHIROU
SUGIMOTO KOJI
INAI SADAO
MORII TAKASHI
KUSUNOKI MITSUHIRO
KAWASAKI STEEL CO