Determination of Appropriate Tightening Torque for Bolted Joint in Railway Coaches

摘要

Bolted Joints are used in machine element, as they are cheap and can be easily assembled and dissembled for the efficient maintenance. In Railway also use of bolted joint is common. However, many troubles such as loosening of bolted joints or fatigue failure of bolt were often experienced. Loosening of bolted joints under a vibratory environment has been an ongoing problem associated with many engineering applications. Bolted Joint becomes loose under vibration, which leads to decreasing of clamping force and finally failure of the system. The object of present study is to determine the appropriate tightening torque for bolted joint in Railway ICF coaches. Five types of bolted joints with hex head nut bolt on different locations in many coaches have been selected in a train rake for the study. The bolted joints were tightened with particular tightening torque by torque wrench. The torque wrench is used for tightening the bolted joints with a torque and marked bolted joints with paint, then loosening angle observed after every trip. The loss of tightening force has been measured at regular intervals by measuring loosened angle to adjudge the loosening of threaded fastener. Then bolted joint tightened with increased tightening torque and loosened angle observed. This process repeated again to find out finally appropriate tightening torque. With the use of this study, the material, man power and maintenance time can be saved and the reliability of the system can be increased.