| 摘要 |
PURPOSE:To enable a threshold corresponding to each unit member of an object to be inspected for a long distance to be set accurately by automatically setting the threshold value based on recognition of a connection part from difference of selected average value of a plurality of measurement positions near front and rear in running direction of an abnormal part. CONSTITUTION:A data processing part 4 measures propagation time for each measurement position 7 after ultrasonic waves are transmitted to an object to be inspected until reflection signal is received by transducers of transmitters and receivers 1a - 1n. Then, it compares it 9 with a threshold which is set previously by a threshold-setting means 10 for specifying an abnormal part. Propagation time at a plurality of measurement positions near the rear and front in running direction of this abnormal part is selected 11, each average value is calculated and compared 9, and then connection part is recognized 12. Thus, an average value of propagation time of front in running direction of the recognized connection part is sent to the means 10, where the threshold value is updated based on it. Therefore, even if dimensions of the object to be inspected is changed, a threshold corresponding to it is automatically set, thus enabling inspection to be performed accurately. |
