Development Of A High-voltage Tower Bolt Fastening And Torque Testing System Controller

The safety requirements for transmission towers in power industry are very strict.Many accidents are caused by loose bolts.In the construction of power transmission towers,numerical control torque wrench is often used to tighten the bolts,so as to ensure the reliability of the transmission towers.The appearance of electric wrench has filled the gap of high-strength bolt tightening automation.It has not only solved the problem of aerial work by lowering the difficulty of working in the small operation space with large torque but has also improved the efficiency of bolt tightening.In the steel structure installation industry,electric wrench is widely used for the fastening of high-strength bolt thanks to its convenient operation,time-saving and labor-saving.With the increasingly sophisticated industrial production of mechanical automation,various mechanical automation equipments also develop rapidly.In the assembly process of the device connection,each bolt requires corresponding tightening torque.Therefore,in order to maintain the normal function of mechanical equipment,different types of bolts need to be pre-tightened correspondingly so as to ensure the reliability and stability of their connections.Especially in the power industry,where high-strength bolt connection widely used,its construction quality directly affects its transmission quality and safety.Hence,it is necessary to effectively control and monitor the state of each bolt's pre-tightening force.However,at present,most existing electric wrenches in the market are single-functioned,meaning that they can only realize the fastening of bolts.Moreover,most CNC torque wrenches only have several gear positions for the tightening of different types of bolts,thereby unable to control the bolt torque accurately.Moreover,considering the poor working environment,it is impossible to detect the torque of bolt fastening.Currently,the electric tools which combine the functions of NC electric wrench and torque detector are still desired.Under this circumstance,Shanxi Power Transmission and Transformation Engineering Company proposes to develop a controller that can not only tighten the bolts of high voltage tower,but also realize torque detection,so as to fill the gap in the domestic power tool market.Aiming at the resolving the defects of existing CNC torque wrench and torque detector,this project develops a controller for the fastening and torque testing of high-pressure tower bolts as required by the manufacturer.The main task of the paper is fourfold:(1)briefly introduces the significance of electric torque wrench in industrial production,and the current situation of domestic electric wrench industry.(2)further explains the role of torque detection in the manufacturing industry as well as the defects of existing torque detection instruments,and different methods of torque detection.Also,this paper proposes a new method of measuring torque which require no torque sensor.(3)based on the introducing of the mathematical model of bolt pre-tightening force,the relationship between load torque,current and motor speed is deduced according to the working principle and working characteristics of the motor and its dynamic equation,which provides a theoretical basis for the development of the high pressure tower bolt fastening and torque testing system controller in this paper.(4)microcontroller as the core,adopts the modular design,control the system hardware circuit design and development,hardware to enhance the durability of the bolt torque tester for each circuit protection module is designed,the software of data acquisition program,at the same time in visual studio for development platform,human interface design,the data is input the query.A reasonable mathematical model is established for the measurement data,so that the measurement accuracy is improved.Through constant debugging and system optimization,the controller design of high voltage tower bolt fastening and torque detection system with large torque in the range of 800-3000N·m is finally completed.Actually used by users,the field test shows that the controller has high precision,simple operation,diversified functions,and is easy to carry.It is especially suitable for on-the-spot testing of bolt torque in aerial work,and has a good market application prospect.At the same time,it provides a new control and testing method for bolt tightening and torque testing of high pressure tower.