PURPOSE: To detect abnormality at an early stage, by simultaneously performing flaw detection when the target arranged in the visual field of an image pick-up apparatus is subjected to actual flaw detection and performing flaw detection on the basis of the flaw signal from a laser disc regeneration apparatus when the flaw rank of the target was changed.
CONSTITUTION: A predetermined target 26 is arranged in the visual field of an image pick-up apparatus 4 and, at the time of the actual flaw detection of a billet 1, the image of said target 26 is simultaneously picked up to be inputted to a signal processor 5 through a switch 27. Next, a flaw level is always monitored by the flaw detection of the target 26 and the preceding flaw level of the billet 1 is successively stored to judge a flaw on the basis of the difference thereof while the switch 27 is changed over to input the reference flaw signal from a laser disc regeneration apparatus 28 to the processor 5 to perform the inspection adjustment of the processor 5. By this method, the processor 5 is always monitored to prevent the lowering in inspection function and the detection and adjustment of an abnormality generation source at the time of the lowering in detection capacity can be performed rapidly.
TADA TAKAYOSHI
IWANAGA TAKASHI
HIRATA MUNEOKI
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