Patent ID: 6705601
Filing Date: 2004-03-16
Classification: C22C,G04B

Abstract:
A self-compensating spiral spring for a mechanical balance-spiral spring oscillator for a watch or clock movement or other precision instrument, made of an Nbâ€”Hf paramagnetic alloy possessing a thermal coefficient of Young's modulus (TCE), such that it enables the following expression 1E&it;&dd;E&dd;T+3&it;Î±s-2&it;Î±bto be substantially equal to zero,where: E: Young's modulus of the spiral spring of the oscillator; 1E&it;&dd;E&dd;T=T&it;â€ƒ&it;C&it;â€ƒ&it;E=thermal&it;â€ƒ&it;coefficient&it;â€ƒ&it;of&it;â€ƒ&it;Young'&it;s&it;â€ƒâ€ƒ&it;modulus&it;â€ƒ&it;of&it;â€ƒ&it;the&it;â€ƒ&it;spiral&it;â€ƒ&it;spring&it;â€ƒâ€ƒ&it;of&it;â€ƒ&it;the&it;â€ƒ&it;oscillator;&agr;s: thermal expansion coefficient of the spiral spring of the oscillator; &agr;b: thermal expansion coefficient of the balance the oscillator; which contains between 2 mol % and 30 mol % Hf, a proportion below the limit above which Hf precipitates.