Design Of Measurement And Control System For Electric Fixed Torque Tightening Wrench Of High Strength Bolt

With the rapid development of high-speed railway construction in China and the improvement of the quality requirements for the overall construction,the state has put forward more strict requirements for all kinds of railway construction equipment tools.In recent years,after monitoring the safety of bolts in steel bridges along some railways,it is found that some bolts are overtwisted or undertwisted or even broken due to the low control accuracy and poor reliability of bolt tightening tools.It greatly affects the quality of the whole railway construction and the safety of the trains.Therefore,the development of a new embedded high strength bolt tightening torque wrench has become a very urgent need of railway bridge construction in China.This thesis introduces the bolt tightening method and the development and present situation of the electric fixed torque tightening wrench at home and abroad and the significance of this research is expounded by analyzing the deficiency of the function and performance of the existing wrench.In view of the deficiency of the existing bridge electric tightening wrench and on the basis of deeply analyzing the function requirement of the new type torque wrench,this paper puts forward the overall scheme of the new type steel bridge high strength bolt electric fixed torque tightening measurement and control system.Through the analysis of the new torque measurement and control system,the author select the STM32F103RET6 as the hardware control core and finish the selection and analysis of each hardware control module,and finally complete hardware and software design of the whole measurement and control system.After the overall scheme is determined,the humanized display and guide interface,the real-time torque display mode and the peak torque control mode are completed by hardware circuit design,and function programming.The functions of parameter setting,static calibration and fast calibration,collecting and storing time information and two-dimensional code information,and the functions of GPRS wireless data transmission and local bolt tightening data storage are also added to the actual requirements of the project function.In this thesis,the precision of torque control is improved by compensating the error coefficient of bolt torque control.At the same time,the fast output torque setting of different bolts torque control and the function of high precision constant torque control are realized by establishing the control error compensation coefficient library for different models.In addition,through the analysis and research of the working mechanism of the standard torque instrument,the fast calibration function of the torque sensor is put forward,which greatly reduces the time and difficulty of the calibration of the torque sensor.Finally,in order to ensure the reliability and safety of the whole function of torque wrench,fault self-diagnosis design and fault tolerant design are carried out to ensure the reliability of torque wrench.The high strength bolt electric tightening wrench has been tested well in actual engineering.Its perfect function and reliable torque control make the torque wrench have certain use value and reference significance.