| 摘要 |
PURPOSE:To make detection with high accuracy, by magnetically detecting the transition point of magnetism of a material to be detected made of hot rolled long sized magnetic substance and performing the ultrasonic wave detection at the point. CONSTITUTION:A stand 3 with rollers 3A and 3B is placed on raisl 2 close to the upper surface of a hot rolled long sized steel piece 1. The steel piece 1 is magnetized with the primary coil of a permeability detecting element 5 on the stand 3 moving on the rails 2 with an air cylinder 4, and the intensity of magnetism is detected with the secondary coil of the detection coil 5 through the change in the magnetic flux when the magnetic field is inverted. On the other hand, ultrasonic wave pulses are transmitted to the steel piece 1 from the transmitter of an ultrasonic wave crack finder element and the reflected wave from flaws is detected at the receiver and the result is displayed on a cathode ray tube 7. The maximum point of the intensity of magnetization is detected with a control circuit 8 by moving the stand 3 toward the arrow A and the air cylinder 4 is stopped via a driving circuit 9. Since the detection is made at high temperatures, the crack finding with high accuracy can be achieved. |
