抄録
The bolted joint has the optimum tightening force to show its sufficient function. Even if the target value of tightening force is obtained, it is a problem to control it in the practical field. Control of tightening force is very difficult though tightening is important in a small screw. Therefore, it is necessary to improve the accuracy of the tightening force in a small screw. The device that simply measured coefficient of friction was produced. Coefficient of friction of a small claimed were requested by the simplified assay. And, the torque factor were able to be led easily. Coefficient of friction of thread surface and bearing surface show the decrease tendency to an increase in the load.
