DISCRIMINATION OF DEFECT IN ULTRASONIC FLAW DETECTION OF ROUND BAR

摘要

PURPOSE:To enable the discrimination of a flaw on the surface of a round bar such as round steel from one therebeneath depending on the shape of a flaw echo output in an ultrasonic flaw detection employing a skew probe. CONSTITUTION:After supplied sequentially to a line, round bars R are sent spirally thereon. A vertical probe 2 for detecting internal flaws is arranged toward the center thereof and skew probes 3 and 3' for detecting flaws on and beneath the surface thereof at an appropriate incidence angle (i) on the feed line, respectively. Signals from the probes 3 and 3' are inputted into a detection circuit 4 to detect, then, gated with a gate circuit 5 and passed through a flaw signal comparator circuit 6. Signals of flaws on and beneath the surface from the skew probes 3 and 3' are applied to a delay circuit 7 through a flaw discrimination circuit 8. The flaw discrimination circuit 8 discriminates a flaw on the surface when any flaw echo output has one peak with the passage of time (as shown by the upper drawing) and a flaw beneath the surface when it has more than one echoes (as shown by the lower drawing).