| 摘要 |
PURPOSE:To ensure the detection of only harmful flaws, in the checking method using eddy current flaw detection, by processing the unavailable part of the detected flaw signals obtained by a rotary type probe, and combining them with the detected signals from a piercing type probe. CONSTITUTION:In the case a flaw F1 in the longitudinal direction is present, the four probes 101-104 sequentially detect the flaw at an interval in response to the rotating speed during the period they are rotated once. A judging device 7 nullifies the pulses which do not appear sequentially at said time interval as noises, with the input from a rotary encoder 105 as a reference. When the pulses, which appear at said time interval, are received (n) times as the signal for the flaw of the longitudinal direction, the signals are inputted to a shift register 61 in a flaw signal combining circuit 6. A probe 20 detects a flaw, which is elongated in the circumferential direction of the round rod steel 30, such as a scab flaw F2. The pulse shaped flaw signal outputted from a comparator 51 corresponds to the scab flaw. In this way, the rotary probe and the piercing type probe cooperate each other and the flaw extending in the longitudinal direction such as crack flaws and the flaws, which is short in size in the longitudinal direction and elongated in the circumferential direction such as scab flaws, can be both detected. |
