Abstract
Various expressions with reference to torque of spiral spring had been studied. But its effective number of turn was unknown or the graphical method to compute it was subtle for industrial spring design.
Author developed the method to draw torque curve by numerical calculations only, basing on Nishihara's plastic formula, and refered these results to experimental ones (Fig.2). From the calculation, also, the relations of torquel, or effective number of turn to spring length and thickness or arbor diameter are cleared up. (Fig. 3.4.5.6).
