Self-compensating spring for clockwork movement spring balance and method for treating the same

摘要

The spiral compensator for a mechanically oscillating balance spiral for a watch movement or other precision instrument is made from an paramagnetic alloy containing at least one of the elements Niobium (Nb), Vanadium (V), Ta, Titanium (Ti), Zirconium (Zr), Hafnium (Hf) and is covered with a sensibly uniform oxide layer with a thickness greater or equal to 20 nano meters formed by submitting the spiral to a anodizing treatment. The alloy is Niobium-Zirconium containing between 5 and 25 per cent of Zirconium. A voltage of 10 to 35 volts is applied to the anodization bath during a period between 10 to 200 seconds. The Youngs Modulus value of the spiral is increased and the couple lowered before anodization to compensate their consecutive values for the formation of the oxide layer.