PURPOSE: To obtain the coil spring having high quantity of spontaneous shape change and excellent in memorizing properties by a relatively simple method by forming a shape memory alloy wire into a coil spring, subjecting the coil spring to shape memorizing heat treatment and thereafter reforming the spring in a direction in which its curvature is reversed.
CONSTITUTION: A coil spring 1 constituted of a shape memory alloy wire is, e.g. transformed into a stretched state and is subjected to prescribed shape memorizing heat treatment. After that, the spring is recoiled in a direction in which its curvature is reversed, and strains are applied thereto. For this purpose, the coil spring 1 in the stretched state is passes through a mandrel 3 as it is, its one end is fixed by a fixing terminal 4 and the other end is fixed to a fixing terminal 4' of a mandrel 3'. The mandrel 3' is rotated, and the spring 1 of the mandrel 3 is recoiled into a spring 1' in an adhered state to the mandrel 3'. At this time, when the recoiling is executed so that the coiling direction in the spring is changed, it is moreover effective. After that, the spring is subjected to two-way shape memorizing treatment of which severe working, aging treatment, training treatment, etc., are independently or compositely executed, by which the two-way shape memory alloy can be obtd.
HORIKAWA HIROSHI
MATSUBARA KAZUO
SUZUKI YUICHI
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