Plastic-Region Tightening of Bolts Controlled by Acoustic Emission Method (Report‪)‬

Introduction A plastic-region tightening method used in the automotive industries is known as a good method for preventing fatigue of bolts. However, the most common tightening-control method by using a torque wrench (called torque-control bolt tightening method) cannot apply to a plastic-region tightening [1]. Both an angle control method and a torque-gradient control method are regulated in JIS (Japanese Industrial Standards) [2] for a plastic-region tightening control, although the method requires a special torque wrench and complicated procedures. We have proposed a new control scheme using AE method, but the accuracy and validity were not examined. In this paper, in order to investigate the accuracy and validity of the tightening-control in field, the tightening test was conducted. The tightening-accuracy and variation by AE method were found superior to those controlled by conventional methods.