| 摘要 |
PURPOSE:To enable measurements of high accuracy by eliminating the necessity of performing the work of setting the amplification degree of a wideband amplifier and a voltage for comparison. CONSTITUTION:An ultrasonic measuring device includes a wideband amplifier 55 for amplifying ultrasonic signals received, a comparator 57 which compares the voltage of each of the amplified received signals with a predetermined voltage for comparison and outputs a logic signal to a time measuring portion 52, and a computer which measures bolt axial forces according to the time required for ultrasonic waves output from the time measuring portion 52 to be transmitted through a bolt and sets such receiving conditions as the amplification degree and the voltage for comparison, so that dispersion of measured values of the bolt axial forces is within a predetermined permissible value. In setting the conditions, the computer employs the permissible value of dispersion of the measured values, the voltage for comparison and the amplification degree as three parameters and first changes only the amplification degree and, when unable to attain optimum setting, also changes the voltage for comparison, so that when optimum setting is disabled all of the three parameters are changed. |
