| 摘要 |
A key 100 comprising bow 110, shank 120, and a joining portion 140 connecting bow to shank; wherein the joining portion 140 comprises a shape memory material (SMA), e.g. a shape memory metal alloy such as nickel-titanium (Ni-Ti, Nitinol) or copper-iron (Cu-Al-Ni, Cu-Zn-Al, Fe-Mn-Si) alloys, the joining portion 140 reversibly deforming when a first torque, i.e. turning force, is exceeded, and the key 100 breaking, e.g. at a weaker part of the shank 120, only when a second and larger torque is exceeded. The SMA may exhibit super-elasticity, i.e. the shape reverts on removing the applied torque, or a shape memory effect, i.e. heating restores the original shape. The bow 110 and/or shank 120 may also comprise a SMA. The joining portion 140 may comprise a cross-section hollow for at least part of its length. The shank 120 may comprise a hollow chamber, e.g. containing an air-setting adhesive, which is exposed when the shank 120 is broken. Also a method of making such key 100 is claimed. |
