What are the factors leading to the inaccuracy of watches?

- Apr 17, 2019-

The factors leading to the inaccuracy of watches


Watches with good minutes and seconds do not exist, either mechanical or quartz watches will have errors. The error of quartz meter is smaller than that of mechanical meter, but this does not mean that the timing accuracy of mechanical meter is not good. There are many reasons that can affect mechanical meter in life. Below is Tianjin Watch after-sales service center to introduce to you the eight major factors that affect the timing accuracy of mechanical watches.


The first reason: external reasons


External cause refers to the external factors of the mechanical watch case. These effects mainly lie in the operating environment of the mechanical meter. The commonly used defensive measures are shock absorber, waterproof device, anti-magnetic device, additional protection, etc. But these can not be completely eliminated, but also depend on their usual care.


The second reason: friction


Friction has both positive and negative effects on mechanical meters. On the positive side, friction has a positive effect on the escaping system. Because of the existence of friction, the escaping system can operate normally, and so can the winding box, so that the kinetic energy of the winding can be accurately stored and released. On the one hand, it is negative, because the existence of friction will produce wear, because the transmission system rubs. Friction reduces transmission efficiency. Only lubricating oil can be used to reduce friction. Ruby should be used to replace the worn parts, such as bearings, because other materials are not hard enough and the machine core is easy to damage. Improve gear surface conditions, including the use of scientific conjugate tooth profile and improve surface finish, but generally no lubrication of the tooth surface (in this case, the resistance of lubricant viscous may be higher than friction).


The third reason: fast and slow needles


Fast and slow needle is an economic structure which is convenient for school hours, but theory and practice have proved that it will affect the isochronism of the system, and may also produce potential differences. These timing errors are random and can not be compensated or offset. Solutions are as follows: to minimize the distance between internal and external fast and slow needles; but the best way is to adjust the speed by adjusting the inertia of the pendulum wheel without fast and slow needles!


The fourth reason: the arrest system


The main influence of escaping mechanism is the influence of energy transfer on the pendulum-wheel yarn system. The pendulum-wheel yarn system can maintain a fixed oscillation frequency only under the condition of free oscillation. Obviously, the energy transfer process of escaping mechanism will affect the oscillation frequency. The theory shows that when the transfer process is close to the balance point of the pendulum, the influence will be reduced. Solutions include: using precision escapement mechanism, such as claw escapement mechanism, its energy transfer process occurs near the equilibrium point, the angle of impulse transmission is very small, and the impact is relatively small. Moreover, its one-way impulse transmission makes the pendulum wheel and the yarn system have more free oscillation space (on this point, its relative error can be reduced by half!). Of course, Swiss leveraged escapement mechanism has the advantages of good workmanship and easy adjustment. It is the mainstream escapement mechanism of the international mechanical meter at present, but in the design, the angle of impulse transmission should be reduced as much as possible. A Swiss company has introduced a coaxial escapement mechanism to reduce the impact of escapement on timing benchmarks. It was invented by a British doctor. But in terms of working principle, it is a mixture of lever escapement mechanism and claw escapement mechanism.


The Fifth Cause: 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 Omega lunar landing surface, with no lubrication or solid lubrication.


Sixth reason: magnetic field


The filament with the greatest influence of magnetic field can change its modulus of elasticity and deformation under the action of magnetic field, resulting in additional stress. In severe cases, magnetic field can cause filament adhesion and seriously affect travel time. The solution is to use antimagnetic materials.


The seventh major reason: hairspring balance


Generally, the center of gravity of framed hairspring varies with the swing angle of the pendulum wheel. Under the action of gravity, it will produce position error. Solutions are as follows: Baoji hairspring is used with center shrinkage and center of gravity not changing with swing angle; Philip's cylindrical hairspring with end curve is used symmetrically up and down; linear hairspring is used; some people have used spherical hairspring in history, which has superior performance, but poor workmanship and little practical application.


The eighth reason: balance of pendulum


The balance problem of the pendulum element directly affects the position difference. The static balance of the pendulum element is a basic requirement. If the above factors are ideal, the running time of the watch is relatively stable. Through the dynamic balance of the watch, the running time performance can be comprehensively improved. There is a very special method: the principle is that when the swing of the pendulum wheel reaches 220 degrees, all kinds of impulses transmitted to the pendulum wheel have no effect on the frequency. Some people used the weighing mechanism installed on the escaping longitudinal wheel to control the swing around 220 degrees, which is also a method.


These are the factors that lead to the inaccuracy of watches.