| 摘要 |
PURPOSE:To improve the discrimination accuracy for the generation of a crack by discriminating whether a point shown by a natural frequency and an output level of a wave type of its natural frequency is within a prescribed area of a two-dimensional plane consisting of the frequency and the output level or not. CONSTITUTION:A percussion is given to an article to be inspected 1 by a steel ball 3, and its vibration is detected by an electromagnetic pick 5, amplified by an amplifier 7 and outputted to a frequency analyzer 9. The frequency analyzer 9 inputs a vibration waveform, based on a timing signal outputted from a delay device, and analyzes a frequency component of a frequency waveform and its output level. Subsequently, whether a point shown by a natural frequency of the frequency waveform and its output level is in a prescribed closed area which is set at every natural oscillation by a setting device 11, of a two-dimensional plane in which the frequency and the output level are parameters or not is discriminated by a discriminator 10. In such a way, the discrimination accuracy for the generation of a crack can be improved. |
