The Design Of Bolt Connection Condition Monitoring System Based On Vibration Phase Difference Of Workpieces

Bolt connection is a very common connection method for workpieces.It is not limited to most mechanical,bridge,and railway track projects.The tightness of the bolt connection is easily affected by the vibration of the workpiece,fatigue corrosion and other factors,resulting in loosening,fracture,loss and other failures,which in turn cause further losses.Major accidents caused by bolt looseness in various projects are also common.It shows that the detection and evaluation of the bolt connection status is of great importance.Traditionally,people determine whether there is a problem with the connection or not by manually judging the tightness of bolts.There are shortcomings that are restricted by the work requirements of the device,the inability to detect for a long time in real time artificially,and certain work environments which are harmful to the test personnel,making people more willing to choose the intelligent system for monitoring,achieving the purpose of high real-time performance and personnel safety.According to the requirements of the bolt connection condition monitoring system based on vibration phase difference and related technical principles,the system consists of four parts: vibration information acquisition module,FPGA system module,CAN bus transceiver module and host computer module.Among them,the vibration information acquisition module consists of a piezoelectric ceramic sensor,an analog operational amplifier circuit,and a high-speed AD converter.The design add in a function that can adjust the circuit amplification factor to make the system suitable for more applications;the FPGA system module contains High-speed AD driver,FIR filter,CAN module driver module and data flow filled function module.Through the design of the AD drive,a single AD sampler on the two signals at low intervals quasi-synchronous sampling can be achieved,through FIR filtering the structural optimization design of the device,the improvement of the performance of the digital filter can be achieved.The CAN bus transceiver module consists of a CAN controller,a CAN transceiver,and a transmission bus.By adding a split terminal,it improves the anti-interference of the transmission circuit and achieves high-reliability transmission of signals.The host computer module includes functions such as data processing and archiving,waveform display,data analysis and calculation,and can implement corresponding processing,calculation,storage and historical data query of the collected data.In view of the lack of real-time performance of the quasi-synchronous DFT non-integer correction algorithm for calculating the phase difference,combined with the data preprocessing mode of the system,a new iteration method is proposed based on the algorithm to adapt to the require of real-time and accuracy of the system.After relevant analysis and test of the improved algorithm,it is concluded that the improved quasi-synchronous DFT non-integer correction algorithm has less computational complexity and higher real-time performance.After completing the construction of a simulation test device and experimental verification,the feasibility and reliability of the system were examined.The system can effectively and clearly reflect the current status of the tested bolt connection,and achieves the purpose of monitoring the bolt connection status.Compared with the previous monitoring technology,the system has the characteristics of high real-time performance,simple operation,and easy application.Judgment of the looseness of bolts by the phases difference can also be used as a new monitoring method.