2006 年 2006 巻 51 号 p. 35-43
Coiled wave springs (CWS) are considered as multiple layered waved washers. They are light but powerful in limited spaces. In recent years, CWS have been applied to clutches of automobiles and expected to be applied to other uses. The formulas on the spring rates and stresses of CWS have been presented by an American spring maker of Smalley Steel Ring Company, Nishio, and Japan Spring Manufacturers Association (for short, JSMA). But none of them are practical, because the accuracy is not enough. Moreover the derivations of the formulas are not clear in the case of Smalley and JSMA. It has been observed that CWS show nonlinear spring characteristics in large deflection, however, the cause has not been made clear. In this research, spring rates and stresses for CWS are analyzed theoretically. A cause of the nonlinear spring characteristics is made clear, too. Then empirical formulas on the spring rates and stresses are derived by comparing the theoretical results with experiments and FEM analysis.