Abstract
In the previous report, the vibration screw tightening method using a D. C. motor was discussed. In the results it was clear that the vibration tightening torque coefficient decreased more than the ordinary tightening torque coefficient, and the amount of scatter of the vibration tightening torque coefficient also decreased and then the screw thread tightened by the vibrational method was hard to loosen. In this report the pneumatic method using an air motor is studied. It is a more compact and controllable device in comparison with the vibration tightening which uses the D. C. motor. Also, the low frequency torsional vibration from 0 to 4 Hz is added to the tightening tool. The basic characteristics of the screw tightening method by means of the pneumatic control vibration is compared with the results of the ordinary screw tightening method (i.e. a constant velocity tightening method using the air motor).
