Abstract: The current use of the Internal Combustion Sleeper Bolt Wrench(ICSBW) without real-time tightening torque display is difficult to meet the accuracy and efficiency requirements when sleeper bolts fastening.Thus,the conventional ICSBW is digitized by increasing the torque measurement and display functions.In the added torque measuring device,the pressure of the compression spring in the safety clutch is measured using a resistance strain pressure sensor;the safety clutch model is simplified and analyzed to determine the linear relationship between the spring pressure and the tightening torque;the linear regression equation between the spring pressure and the tightening torque is established by analyzing the digitalized ICSBW experiment data with SPSS software.The correctness of theoretical analysis and the feasibility of the program are testified by comparing the ratio obtained between the theoretical and experimental analysis.The cost of the digitalization of ICSBW is low and the working efficiency and precision are greatly improved with the use of the digitalized ICSBW.

Key words: bolt wrench, digital display, spring pressure, tightening torque, linear relationship