| 摘要 |
PROBLEM TO BE SOLVED: To provide a crack-detecting device for detecting the presence or absence of the crack of a welded part on an entire surface regardless of the shape of the welded part. SOLUTION: A sound-collecting microphone 36 is mounted to a closed space that is subdivided and formed by the inner wall of a recessed part including welded parts 23a, 23b, and 23c of a panel and a rubber pad 40, and an ultrasonic wave with a prescribed frequency is discharged from a tweeter 32 being mounted to the upper portion of the inner wall 20 that is positioned at the left and right of the rubber pad 40 to the entire surface of a panel 22 with the welded parts 23a, 23b, and 23c of the panel 22 as a center. As a result, if either of the welded parts 23a, 23b, and 23c has a crack 23x, an ultrasonic wave with a specific frequency being propagated into a closed space that is connected via the crack 23x is captured by the sound-collecting microphone 36, thus judging an electrical signal with a sound pressure level exceeding a detection judgment threshold using a judging device 38 and detecting the presence of the crack 23x. |
