Torque Characteristics of Spiral Spring Made of Ti-Ni Superelastic Alloy Wires

The objective of this study is to develop a new spiral spring that exhibits unique deformation behavior. The properties of the spiral spring make it suitable for use not only as an energy storage element but also as an actuator or similar device. In the present study, a process for manufacturing a spiral spring made of Ti-Ni superelastic alloy wires was proposed. In addition, torque characteristics of the manufactured spiral spring were investigated by torque measurement tests. Rotational torque during wind and rewind processes at a constant rotational speed was monitored. In addition, torque measurement tests were repeated to investigate the effect of the number of wind and rewind processes on the torque characteristics. Two main results were obtained. First, the torque characteristics of the spiral spring show torque plateau behaviors, which are expected to produce a constant energy output. Second, the torque characteristic depends on the number of torque measurement tests. Torque values decrease with increasing number of repeated tests. These results for the spiral spring correspond to the superelastic behavior of the Ti-Ni alloy.