On line monitoring device of bolt pressing force

Aiming at the problem of loose bolt connection in engineering, an on-line monitoring device of bolt tightening force based on piezoelectric effect is designed. The device uses two piezoelectric ceramics as the core of the sensor, one as the active chip to generate ultrasonic wave, and the other as the receiving chip to receive the ultrasonic output electrical signal. The device analyzes the electrical signal related to the connection state output from the receiving chip on the built-in circuit board, and then sends the data which can represent the bolt connection state after analysis to the remote receiver in a wireless way, and gives an alarm at the receiving end for the data exceeding the threshold value. In addition, the device can automatically switch between working mode and sleep mode, greatly reducing power consumption, and can work for a long time with solar power supply system, without frequent battery replacement. The experimental results show that the device can evaluate the current connection state of bolts and work stably for a long time. It has a good prospect in the field of bolt connection condition monitoring.