| 摘要 |
PROBLEM TO BE SOLVED: To perform the measurement of a load applied to a part without depending on a coupling material by using an electromagnetic to acoustic transducer (EMAT) for generating and receiving an ultrasonic wave without requiring the contact with a part such as bolt, and measuring the change of transfer time of an ultrasonic signal traveling within the bolt. SOLUTION: An EMAT assembly 20 is arranged on a bolt 2 side within the internal space 17 of a socket 15. The assembly 20 is formed of a housing 22, and a permanent magnet 28 for generating magnetic field and an EMAT coil 26 for generating current, which are arranged on the inside of an abrasion plate 24. The assembly 20 is connected to a socket driving assembly 10 by a mounting bolt 21 and a spring 23. An ultrasonic wave is directly generated on the surface of the bolt 2 by the current of the coil 26, and the time from the current pulse to the first reflection is measured to provided a precise transmission time of ultrasonic wave. This device is of contactless type with high reproducing precision for generating and detecting ultrasonic wave. Thus, interposition of a liquid coupling between a transducer and a non-inspecting material is eliminated. |
