FABRICATION METHOD OF UNIQUE TWO WAY SHAPE MEMORY COIL SPRING AND UNIQUE TWO WAY SHAPE MEMORY COIL SPRING FABRICATED BY USING THE SAME

摘要

PURPOSE: A method for manufacturing a multi-stepped contractible shape memory coil spring in which a multi-stepped contractible behavior is possible and a multi-stepped contractible shape memory coil spring manufactured by the same are provided to adjust a contraction behavior in multiple stages because a shape memory coil spring is applied to the actuator so that the actuator is applied to various machine components and driving devices. CONSTITUTION: A method for manufacturing a multi-stepped contractible shape memory coil spring is as follows. An alloy wire rod of the NixTi100- x (49=x=50.5) composition is manufactured. The alloy wire rod is processed as a contact-type coil spring having a spring index more than 5. The coil spring is heat treated at a temperature of 400C to 800C. A stress is added on the spring at room temperature and the spring is expanded and the expanded coil spring is cooled at below martensitic transformation temperature after the expanded coil spring is contracted by a current. Expanding and cooling processes are repeated.