Abstract
A testing apparatus to measure coefficient of sliding friction between bolt and nut is producted. The axial compressive force is measured by three compressive helical coiled springs as shown in Fig. 1 and 2. A, B is the first set of bolt and nut, and A', B' the second. The spindle C fixed to A and A' by means of serration of C is turned slowly, and the torque to resist sliding friction between A and B, A' and B', is measured by F which is attached to the center of pendulum-shaft of torsion testing machine. The value of coefficient of friction is calculated by this torque and axial compressive force of springs, using equation (2). The value of coefficient of friction is about 0.2 between slightly lubricated mild pieces, and the value decreases with the increase of compressive force, as shown in Fig. 11-17. The typical diagrams of torque and twisted angle are shown in Fig. 5-10.
