ULTRASONIC BOLT AXIAL FORCE MEASURING DEVICE

摘要

PURPOSE:To correctly measure the bolt axial force by detecting the maximum peak position in the range corresponding to the half-wavelength width of the resonance frequency of a probe after the bottom face echo exceeds the preset threshold. CONSTITUTION:A probe 4 is brought into contact with the head section of a measured bolt 1 inserted into fastening members 2, 3. A ultrasonic transceiver section 6 transmits a transmission pulse signal to the probe 4 and receives the reception signal of the ultrasonic echo from it. An A/D converting circuit 7 converts the reception signal into a digital value and sends it to a measurement data processor 16. A CPU 9 detects the first data position Q1 exceeding the threshold TH from the bottom face echo data and detects the maximum peak P in the range of the half-wavelength width W of the resonance frequency of the probe 4. When the axial force is applied to the bolt 1, the propagating time of the echo signal is increased in response to the generated axial force. When the increase quantity of the propagating time of the bottom face echo is measured, the applied axial force is calculated.