Method for manufacturing a balance-spring obtained according to said method
AssigneeETA SA Fabriques d'Ebauches
InventorsPhilippe Marmy, Eric Favre, Christoph Schlencker
Life of this patent
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Abstract
A method for manufacturing a balance-spring for a clockwork movement wherein a spring is formed by winding, from a wire or metal strip, said spring including an inner end intended to be fixed to a balance and a outer end zone intended to be fixed to the balance-spring stud and wherein the whole spring is subjected to a first heat treatment subsequent to the winding step of said wire. The method of the invention is characterized in that it further includes an additional step consisting in subjecting at least said outer end zone to a second heat treatment. This method improves in particular the shock resistance of the balance-spring.
Claims9
A method for manufacturing a balance-spring for a clockwork movement wherein a spring is formed by winding, from a wire or metal strip, said spring including an inner end intended to be fixed to a balance and a outer end zone intended to be fixed to a balance-spring stud and wherein the whole spring is subjected to a first heat treatment subsequent to the winding step of said wire, the method further including an additional step of subjecting at least said outer end zone to a second heat treatment.
A balance-spring for a clockwork movement formed of a wire or a strip wound in a spiral including an inner end intended to be fixed to a balance and an outer end zone intended to be fixed to a stud, wherein at least said zone has a hardness less than that of the rest of the balance-spring.
Dependencies are inferred from the claim text.