| 摘要 |
PURPOSE:To enhance the directionality of ultrasonic beam and the intensity level of a receiving signal, by constituting a magnetic pole applying a magnetic field to a material to be inspected of two magnetic poles having magnetic fields reversed to each other. CONSTITUTION:Permanent magnets 10 made of plastic generating static magnetic fields reversed to each other have high electric resistance and the eddy currents in the magnets are not almost generated. The magnets 10 are sealed by a sealant 18 in order to block the electromagnetic wave of the outside and shielded by an earth wire 19. A control panel 17 has a pulse generator and has function for amplifying and analyzing receiving voltage. The pulse current transmitted by the control panel 17 passes through a signal transmitting wire 20 to flow through a transmitting-receiving coil 7. At this time, an eddy current 11 is generated in a material 1 to be inspected by a mutual induction phenomena and acts on the static magnetic fields reversed to each other to generate Lorentz forces 13 the same in a phase and said Lorents forces 13 become ultrasonic waves 16 the same in a phase to propagate through the material 1 to be inspected and return while reflecting therefrom to generate induced electricity. This electricity is received by the coil 5 through mutual induction and amplified and analyzed by the control panel 17 to make it possible to perform ultrasonic measurement. |
