SHAPE DETECTION METHOD OF ABUTTING PART OF WELDED STEEL PIPE, QUALITY MANAGEMENT METHOD OF WELDED STEEL PIPE USING THE SAME AND DEVICE THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a shape detection method of an abutting part of a welded steel pipe capable of accurately detecting a difference of the abutting part of the welded steel pipe without requiring a high speed data processor and a composite mechanism.SOLUTION: In a shape detection method, a shape coordinate data L of a specific detection range containing an abutting part 12 which is developed in a two dimensional plane is provided by scanning a non-contact means onto the abutting part 12 of the welded steel pipe, with respect to the shape coordinate data L, a starting point A and an ending point D of the specific detection range, a coordinate of a first selection point B located between the starting point A and the abutting part 12, and a second selection point C located between the abutting part 12 and the ending point D is selected, a first approximate circle α1 containing the starting point A, the ending point D and the first selection point B and a second approximate circle α2 containing the starting point A, the ending point D and the second selection point C are calculated and a deviation between the obtained first approximate circle α1 and second approximate circle α2 is used as an index for expressing the shape of the abutting part 12.SELECTED DRAWING: Figure 5