A New Tightening Method of Bolt/Nut Assembly to Control the Clamping Force

The clamping force of a bolt/nut assembly greatly influences its strength. However it is well-known that the clamping force of a bolt/nut assembly tightened by the torque control method varies widely. In this study, a new tightening method of a bolt/nut assembly that controls the clamping force more accurately has been proposed. In the proposed method, a bolt/nut assembly is tightened by pulling the bolt thread portion protruding through the nut with a force corresponding to the target clamping force. Experiments to verify the usefulness of the proposed method have been performed. The results show that the proposed method can accurately tighten a bolt/nut assembly with an error of approximately ±10% in relation to the target.