Spring Characteristic and Stress of Coiled Wave Spring

Abstract

The coiled wave spring is considered as a multiple layered waved washer, which shows powerful spring force in a limited space. In recent years, some automobile makers adopted them for clutch springs. The application of the spring to other fields has been expanding more and more. But the industrial standard has not been established, yet. In this research, the spring characteristics and the stress of coiled wave springs are analyzed. And the formulae on the spring constant and the stress are derived. Furthermore the formula on the nonlinear spring characteristics is derived. Moreover, some experiments and the Finite Element Analysis are conducted to confirm the validity of the analytical results. As a result, it is confirmed that the analytical results on the spring characteristic agree with the experimental ones. The formula on the spring constant in linear analysis gave the almost average slope of the spring characteristic curve, which means that the formula is useful practically. But the ones on the stress only agree qualitatively. Therefore the theoretical results on the stress must be multiplied by a correction factor of 0.8.