| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2004: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Constant- force springs and coiled-wave springs with a high-performance are often used in various engineering applications that require constant force characteristics such as lift cord mechanisms for window blinds, sliding shelf mechanisms and the mechanisms for raising/lowering commercial camera stands. These springs do not demonstrate a proportional relationship between load and deformation. There are very few theoretical studies about constant- force springs. Considering the strain energy necessary for flattening a coil spring, Votta proposed an analytical theory of a spring. This theory, however, could not be applicable for all stages of displacement, especially for small displacements, because the uncoiled length of the spring can not be flattened. The load, according to Votta's theory, is unable to accurately represent all the stages of the spring's actual deformation, particularly the transient rapid increase of the load. On the other hand, there exists an experimental analysis about coiled-wave springs.
In this research, we reconsider the deformation of constant-force springs and coiled-wave springs as a "problem of large elastic deformation" and perform a new theoretical analysis spring based on the nonlinear theory. Then, we clarify not only the accurate load characteristics of the springs, but also the entire state of spring deformation in the loading process. Furthermore, the experimental verification is carried out using commercially available constant-force spring and coiled-wave springs. The theoretical values are in good agreement with the experimental ones. Consequently, the new theory proves to be useful for evaluation of spring characteristics with a high-performance.
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