GB1323079A - Ultrasonic measuring apparatus - Google Patents

Abstract

1323079 Ultrasonic length measurement BRITISH STEEL CORP 19 April 1971 [9 Feb 1970] 6026/70 Heading H4D The length of a metal billet or other elongated section is measured by transmitting an ultrasonic pulse into the section and measuring the time for the pulse to be reflected back from the far end by a counter which gives a direct reading of the length, the counter only being stoppable during a selected period in which the reflection is expected. The section, which may be in a stack and accessible only at one end, is coupled to transducer 2 by a film of grease. Ultrasonic generator 6 is pulsed by low frequency source 8 e.g. at 2 c./s. The reflected pulse is received by 2 and the resulting signal is passed to amplifier 10, rectified by 12 and passed to further amplifier 14. The signal from source 8 is delayed by monostables 18, 20 and fed to gate 16, the delay being adjusted so that gate 16 is only operable during a period when the reflected pulse is expected, amplifier 14 also feeding gate 16. Source 8 also controls monostable 26 which opens gate 22, the gate controlling gate 30 via inverter 28. Gate 22, when open, opens gate 30 allowing access to counter 34, supplied with pulses from clock 32. The clock frequency is adjusted so that for a given material the count indicated on readout tubes 40 is a direct indication of the length. Reception of the reflected pulse fires monostable 24 and closes gate 22 stopping the count. Further monostables 42, 44 fed by source 8 reset the counter after a time sufficient for the count to be read.