| 摘要 |
PURPOSE: To surely detect the integrity of a tightening bolt with a hexagon socket and improve reliability. CONSTITUTION: A liquid such as water 4 is sealed in a gap between the head part of a bolt 1 and a tightening body 2. Propagation loss and refraction of an ultrasonic wave are produced therebetween according to the differences of sound speed and density of both the members 1, 2 and water 4, and since the propagation of the ultrasonic wave is possible between both the members 1, 2, which are an acoustically integral structure, the restriction of the incident condition of the ultrasonic wave restricted by the shape of the bolt 1 is eliminated. A supersonic beam 6 is made incident to be at right angles to a cracking face produced on the neck lower part of the bolt 1. |
