Device and method for securing a pallet-stone to an escapement pallet of a timepiece movement
The invention concerns a device for securing a pallet stone to an escapement pallet including at least one housing for receiving said pallet stone, characterized in that the portion of the pallet including said housing is made of a shape memory alloy able to undergo a reversible transformation from an austenitic crystallographic phase to a martensitic crystallographic phase.
1. A device for fixing a pallet-stone on an escapement anchor comprising:
at least one seat provided to receive the pallet-stone, said seat having a longitudinal axis, wherein a portion of the anchor comprising the seat comprises a shape memory alloy adapted to undergo a reversible transformation from an austenitic crystallographic phase into a martensitic crystallographic phase, wherein the seat is bounded by jaws configured to re-close in a direction of the seat, wherein a first jaw is fixed and a second jaw is movable between a first unclamped position in which the pallet-stone may be introduced into the seat and be shifted therein along said longitudinal axis, and a second clamped position in which the jaws clamp the pallet-stone fixedly and immobilize the pallet-stone in the seat and wherein the first jaw has two flat clamping surfaces in alignment and separated by a recess, and wherein the second jaw has a clamping surface disposed essentially parallel to facing the two clamping surfaces of the first jaw in the clamped position.
2. The fixing device according to claim 1 , wherein the portion of the anchor comprising said seat does not clamp the pallet-stone substantially when the portion of the anchor is in the martensitic crystallographic phase so that the pallet-stone may be shifted in said seat and wherein the portion of the anchor comprising said seat clamps the pallet-stone fixedly when the portion of the anchor is in the austenitic crystallographic phase while the portion of the anchor is at ambient temperature.
3. The fixing device according to claim 1 , wherein the portion of the anchor comprising said seat does not clamp the pallet-stone substantially when the portion of the anchor is in the austenitic crystallographic phase so that the pallet-stone can be shifted in said seat and wherein the portion of the anchor comprising said seat clamps the pallet-stone fixedly when the portion of the anchor is in the martensitic crystallographic phase while the portion of the anchor is at ambient temperature.
4. The fixing device according to claim 1 , wherein said shape memory alloy is a nickel and titanium alloy.
5. The fixing device according to claim 1 , further comprising a spot of adhesive extending on to the pallet-stone and the anchor in order to stabilize fixation of the pallet-stone on the anchor.