SIGNAL TRANSMISSION MECHANISM OF ULTRASONIC FLAW DETECTOR

PURPOSE:To transmit an ultrasonic wave signal stably by arranging a rotation-side electrode and a flaw detecting device side electrode on the outer peripheral surface of a rotating shaft, and forming a gap of an air layer between both electrodes by the fast rotation of the rotating shaft and obtaining a capacitor. CONSTITUTION:A probe is provided outside the rotating shaft 13, a body to be detected is inserted into the rotating shaft 13, and the probe is rotated together with the rotating shaft 13 to perform flaw detection. The flaw detection signal is transmitted by a transmission mechanism 20. This mechanism 20 has rotation side electrodes 30a and 30b on the rotating shaft 13 and flaw detecting device side electrodes 40a and 40b are wound around the electrodes 40a and 40b as a hot-side and a ground-side electrode. Further, the eletrodes 40a and 40b are formed of thin metallic plates 41, whose tension is adjusted by a spring 43. Then when the rotating shaft 13 is rotated at a high speed, the electrodes 30a and 30b, and 40a and 40b also rotate at a high speed and air layers are wound in between both electrodes 30a and 30b, and 40a and 40b to float the electrode 40 and form a gap, so that the electrostatic capacity formed therein transmits an exciting signal to a coaxial cable 21. Therefore, even if the rotating shaft rotates at a high speed, the temperature does not rise because of the air layers between both electrodes and the signal is transmitted stably.