Research And Design Of High Strength Bolt Tightening And Inspection System

High strength bolts are made of high strength steel and need to be applied with large preload.Electric tightening tools are increasingly playing a more important role in railway construction.Using electric tightening tools to tighten high-strength bolts solves the accuracy problem of torque control in the process of tightening,and reduces the labor intensity of workers.The quality of bolts often affects the safety of facilities.In the construction process,a large number of bolts are used.Due to improper operation of workers or improper use of electric tightening tools,over tightening and under tightening of bolts will be caused.Bolts exposed to the external environment for a long time will also be loose or even fall off.The existing electric tightening tools on the market have single function,which only realize the tightening of bolts,but can not realize the detection of over tightening,under tightening and missing tightening of bolts.The traditional detection scheme often requires the use of human torque wrench or professional preload detection equipment,the torque wrench has high requirements for operators and the use range is limited;the professional preload detection equipment is expensive and bulky.How to develop an electric tightening tool which can be used for both high-strength bolt tightening and in-service bolt state detection has become the research content of this paper.According to the actual needs of the subject,aiming at the defects of the existing electric tightening tools and preload detection equipment,this paper designs a system composed of electric tightening tools and Android mobile terminal,including bolt tightening control and tightening torque detection.Among them,the electric tightening tool mainly collects the value of torque sensor through a/D module,and uses STM32 chip to realize the precise control of torque.The detection of over tightening and under tightening of bolts is based on the advantage of small inertia impact of DC motor,and the tightness state is detected by torque value.Android mobile terminal and tightening tool interact with each other through Bluetooth connection.Around the function of electric tightening tool,the hardware circuit design,component layout and main control chip program design are carried out.According to the function of Android mobile terminal,the interface layout and program design are carried out.Finally,through the field function debugging and experimental verification,the overall tightening control and tightening torque measurement functions are verified to ensure the integrity and reliability of the system function,and the overall function of the system meets the design requirements.