| 摘要 |
<p>In a method of flaw classification on and in welds of planar or accurate plate-shaped workpieces of uniform thickness by means of ultrasonics the expected flaw areas of the workpiece pre-examined manually are examine systematically by using the ultrasound echo image method in separate cross-sectional planes for generating a s-scan, changing the position of the transducer means on the workpiece and/or the transmitting direction, and for locating defects calculating the delay time of ultrasound waves in the go-and-return directions within the workpiece under consideration of possible reflections at the rear side of the workpiece. For defining the test conditions, part specific parameters are considered, such as weld type, weld shape, e.g. double-V-weld, bell seam, weld geometry, e.g. seam angle, part characteristics, e.g. wall thickness, where upon with the aid of a computer into which said parameters have been inputted, to a graphic representation corresponding to a s-scan is drafted. In said graphic representation at least one area, in which the density of obtained reflection points per unit of area exceeds a predetermined value, is surrounded by a closed curve of second order, generally an ellipse, and the angular direction of a privileged axis, particularly the major axis of the ellipse, in relation to a reference system, the axis ratio and/or the center location are calculated. Furthermore reflection points of a defect located oppositely to each other are detected and the ratio between length and thickness of the defect or the orientation tendency, respectively, is calculated, whereupon at least by logically linking orientation tendency and path difference a discrimination between volumetric-type defects, planar defects and combination defect is brought about.</p> |
