| 摘要 |
<p>A parameter representative of a physical property of a continuously moving metal strip is determined by repetitively generating acoustical shock waves, containing ultrasonic frequencies, and adjacent the strip and measuring the speed of transmission in the strip. In one embodiment, an electric spark generator 11 with a collimator 14 feeds the acoustic energy to the strip 10 and four microphones arranged as a first pair 20, 21 on opposite sides of the strip spaced a known distance from a second pair 22, 23 also on opposite sides of the strip pick up the signal transmitted through the strip. The difference between the mean time of arrival at 20, 21 and the mean time of arrival at 22, 23 enables the velocity of propagation in the strip to be determined despite movements of the strip verse to its plane. The velocity of propagation in particular may be used as a measure of Young's modulus and hence, in the case of a material such as aluminium, as a measure of the temperature of heat treatment.</p> |
