2016 年 2016 巻 61 号 p. 25-32
In general, springs are flexible machine elements used for controlled application of force (or torque) or for storing and release of mechanical energy. A coiled wave spring (CWS), also known as a scrowave spring is a compression spring made of coiled wire or thin plate with waves giving a spring effect and offers the unique advantage of space savings when used to replace conventional coil springs. By reducing spring operating height, the coiled wave springs also offers a decreased spring cavity. A production cost savings is realized with a smaller assembly size and less material used in the manufacturing process. CWS makes it possible to accommodate higher thrust load within the limited axial space depending on the size of the wire (or plate), the number of waves, the height of waves, and the number of turns. In recent years, CWS with very high performance are widely applied to “Slip Clutch” and “Multi-Tooth Cutter”, “Retaining Ring”, “Face Seal”, and so on. However, nonlinear characteristics observed in large deformation of CWS has not been made clear yet. The large deformation analysis has been eagerly looking forward to as calculation formula. As it is, there exists no persuasive analysis. In this research, these nonlinear characteristics and spring constant for CWS are analyzed theoretically. A nonlinear large deformation theory is applied and exact analytical solutions are derived in terms of elliptic integrals, and then put into a nondimensional formula to facilitate the common understanding of large deformation phenomenon. Moreover, three concepts for the spring constant are newly proposed. In this study, some experiments were presented and the experimental results were compared with the theoretical formulas. As a results, the relation between the applied axial compression force and the nonlinear deflection obtained from the experiments is in good agreement with the relation predicted by the analytical theory.