| 摘要 |
PURPOSE:To accurately detect the position of a welded part, by allowing lights to alternately irradiate the surface of the welded part formed to the outer surface of a seam weld pipe from both left and right side light projectors and receiving left and right surface brightnesses due to the irradiated lights to compare both brightness signals. CONSTITUTION:Left and right side light projectors 3A, 3B are arranged to both sides of the light receiver 4 arranged directly above the welded part 2 of a seam weld pipe 1 and allow lights to irradiate the surfaces of the welded part 2 and the surfaces of matrix parts 1'A, 1'B in the vicinity of said welded part. The lights from both light projectors 3A, 3B cross the axial line of the electroforming pipe 1 at right angles and pass through the central part of the welded part 2 in the lateral direction thereof to be inclined by an angle theta to the straight line (l) extending to the diameter direction of the electroforming pipe 1 while these irradiated lights are regularly reflected from the surfaces of the matrix parts 1'A, 1'B in the vicinity of the welded part and only the lights regularly reflected from the surfaces of the matrix parts 1'A, 1'B among reflected lights are directly incident to the light receiver 4. Therefore, when lights are allowed to irradiate the surface of the welded part 2 of the seam weld pipe 1 and the surfaces of the matrix parts 1'A, 1'B in the vicinity of said welded part 2 from the left and right light projectors 3A, 3B, a brightness signal having a peak is obtained from the light receiver 4 to enable the positional detection of the welded part. |
