| 摘要 |
PURPOSE:To prevent a wrong judgement to a possible extent and improve reliability of crack detection, by dividing a crack detecting range basing upon a generation time of an AE wave caused by a crack in a work and allowing a counting circuit per each individual division to operate. CONSTITUTION:When a work 4 is without a crack, even if a sensing signal is delivered to a pulse-forming circuit 9 from an AE sensor 6, no pulse is formed and consequently, no counting is performed either on a counter 12 or a counter 13. A crack in the work 4 causes an excess of wave element over a set level 1, forming of a pulse by the pulse-forming circuit 7 and input of a high-level pulse signal into accounting circuits 17, 18. When a counter counts on input of timing circuit 16, this count value and set count value become equivalent and thus, a judgement signal of crack on the work 4 is delivered to a judgement display unit 1 as an output. For reopening, the operation is followed by resetting. |
