Patent ID: 7954822
Filing Date: 2011-06-07
Classification: F16J

Abstract:
1. A wire material, wherein a cross-sectional shape of the wire material is a generally rectangular shape comprising two flat surfaces at the shorter sides, a convex curved surface at one longer side and a concave curved surface at another longer side, when the coil expander is formed by coiling the wire material, the convex curved surface of the wire material is deformed to be a flat surface constituting an outer peripheral surface of the coil expander, when the coil expander is formed by coiling the wire material, the concave curved surface of the wire material is deformed to be a flat surface constituting an inner peripheral surface of the coil expander, a height “a” of the convex curved surface, which is a distance between a straight line connecting outer edges of the two flat surfaces and an apex of the convex curved surface, a height “b” of the concave curved surface, which is a distance between a straight line connecting outer edges of the two flat surfaces and an apex of the concave curved surface, when the height, in the surface of the wire material, of the convex curved surface is “a” and the height, in the surface of the wire material, of the concave curved surface is “b”, a≧b+0.005 mm, the height “a” of the convex curved surface is in the range of 0.03 to 0.1 mm, and the wire material is formed of a shaped memory alloy.