What are the factors affecting the timing accuracy of mechanical meters?

- May 17, 2019-

1. Friction

Friction usually has both positive and negative effects. On the one hand, it has positive effects, such as friction wheel splitting, friction between automatic spreader and bar box, screw self-locking, etc. On the other hand, friction will lead to the reduction of transmission efficiency and friction loss of parts, thus affecting the timing. Commonly used solutions: improve lubrication conditions, according to different requirements, choose different lubricants; use gemstone bearings or gaskets; improve gear tooth surface conditions, including the use of scientific conjugate tooth shape and improve surface finish, but generally no lubrication (in this case, the resistance of lubricant viscous may be higher than friction).

2. Temperature effect

The influence of temperature is mainly manifested in two aspects: firstly, the change of temperature will affect the working length of the hairspring and the inertia of the pendulum wheel, which can directly affect the timing accuracy; secondly, the change of temperature will affect the viscosity of lubricating oil and transmission efficiency, thus affecting the timing. The following methods can be adopted: open bimetallic temperature compensation pendulum spindle system; special alloy material is used to make the pendulum spindle and the pendulum spindle, so that they have a certain temperature compensation in the working temperature range (8 -38); and moving fast and slow needle temperature compensation. Standard lubricants are used for extreme temperature conditions, such as the Lunar Landing Surface of Omega, a world-renowned watch, with no lubrication or solid lubrication.