A wrist watch with a flat or a breguet - the coil spring.

摘要

Flat spring or Briguet sprial for a wrist watch, having a rectangular cross-section, has a length of 20-33 cm (pref. 23-27 cm.) and pref. a pitch 2-3 times the spring thickness. The spring is pref. made from an alloy contg. (in %): Ni 37-40, Cr 7-9, Ti 0.5-1.5, Be 0.5-0.9, Mn 2, the balance being Fe. This alloy is known as "Nivarox" (RTM). The springs have minimal anisochronism, i.e. theri oscillation frequency depends only very little on the oscillation amplitude. The modulus of elasticity of "Nivarox" is practically independent of temp fluctuations.