| 摘要 |
PROBLEM TO BE SOLVED: To provide a coil spring having shape memory effect reversible in a radial direction with respect to a temperature cycle such that a spontaneous shape when heated is elongated in the radial direction, and a spontaneous shape when cooled is shrinked in the radial direction. SOLUTION: A wire rod obtained by subjecting a TiNi based alloy having a main composition containing Ni in the range of 50.3 to 53.0 atomic %, and the balance Ti to the treatment of hot working and cold working is wound around a columnar first bar-shaped member 11 so as to tightly be adhered and is subjected to the heat treatment of single phase transforming treatment to obtain a coil spring of a TiNi single phase, and, thereafter, the coil spring is wound around a second bar-shaped member having a radius larger than that of the columnar bar-shaped member so as to tightly be adhered, is formed and is subjected to aging treatment to form a coil spring having shape memory effect in which, spontaneously, the shape changes so as to be elongated in the radius direction when heated, and be shrinked in the radius direction when cooled. |
