How Does the Shock Absorber Protect the Pendulum Shaft From Being Broken


Today, let’s talk about the basic knowledge of watch shock resistance that you should know.

First of all, let’s look at the structure and principle of the watch shock absorber. By installing a shock absorber on the swing shaft of the watch, it becomes a shock-resistance watch. In order to improve the vibration accuracy of the balance spring system, the use of a finer shaft diameter is one of the effective measures. The pinch fine energy reduces the frictional resistance of the balance wheel movement, but the thinner journal is easily broken, and the shock absorber is a reasonable device to overcome this disadvantage.

The shock absorber is composed of anti-vibration pedestal, shockproof bowl, spherical arc hole drill, support drill, anti-vibration spring and other main components. The shockproof bowl and the shockproof pedestal are matched by a cone surface, and the anti-vibration spring presses the shockproof bowl by the drill. When the shockproof bowl is off center, due to the elastic force of the anti-vibration spring, the shockproof bowl slides along the smooth cone of the shock pedestal to the original position, this is called the reset performance of the shock absorber and is an important indicator for checking the quality of the shock absorber. Each watch is equipped with two shock absorbers, a shock absorber is on the swing plate, and the other shock absorber is on the main plate. The upper shock absorber is fixed on the swinging plate with a U-shaped pin, and the lower shock absorber is directly pressed into the slot of the main clamping plate. Their structural principles are identical, but the thickness of the drill is different, and the upper anti-drill is 0.09 mm thicker than the lower anti-trailer.

Then, let’s take a look at how the shock absorber protects the pendulum shaft from being broken. It is divided into the following three cases. First, when the watch falls horizontally on the ground, the swing shaft has an axial impact force, causing the swing shaft to move in the axial direction, and the swing shaft moves the drill upwards until the end of the swing shaft contacts the shock mount. During this process, the drill moves upwards to deform the anti-vibration spring. The elastic force of the anti-vibration spring will hinder the rapid movement of the pendulum shaft, and the last remaining impact force will be borne by the end face of the pendulum shaft. Therefore, the force of the anti-vibration spring must be matched with the force that the pendulum journal can withstand. If the anti-vibration spring is too hard during the heat treatment, the pendulum shaft is easily broken when subjected to an external force in this direction.

In the second case, when the watch is dropped vertically on the ground, the pendulum shaft is subjected to a radial impact force, which causes the pendulum shaft to move in the radial direction, and drives the shockproof bowl to move upward along the anti-vibration pedestal cone until the pendulum shaft cylindrical surface contacts the anti-vibration pedestal, the movement stops. Due to the upward movement of the anti-vibration bowl, the anti-vibration spring is deformed, and the movement of the pendulum shaft is also buffered and weakened, and the remaining impact force is borne by the cylindrical surface. In the manufacturing process, if the smoothness of the contact surface between the shockproof bowl and the shockproof pedestal cannot meet the design requirements, the shockproof bowl cannot move upward along the anti-vibration pedestal cone, and the swing journal is easily broken.

In the third case, when the watch is tilted and dropped on the ground, the swing shaft is subjected to an axial and radial mixed impact force, and the above two buffers simultaneously act to weaken the swing shaft motion, and finally the end surface and the cylindrical surface simultaneously bear the remaining impact. Shock absorbers generally come into play when the components of the shock absorber are fully compliant with tolerances. However, the performance of the shock absorber is limited. When the impact force of the watch is large, beyond the effective range, the pendulum shaft, the shock absorber and other components may be damaged.

Then, I will introduce the automatic turning shockproof bowl, anti-vibration pedestal processing. The turning shockproof bowl and the shockproof pedestal are made of lead brass, and the main process is completed on a single-axis slitting automatic lathe. The processing of the anti-vibration spring and the U-shaped pin is based on the stamping of the mold on a precision punching machine, and then deburring, heat treatment, and electroplating. The anti-shock bowl and the anti-vibration seat must be equipped with the required cam according to the shape and dimensional accuracy of each surface, and the tasks of each tool are assigned to determine the processing sequence and adjustment method. Since both the drill and the shockproof bowl rely on the pressure of the anti-vibration spring and are positioned by the taper on the outside of the shockproof bowl and the taper inside the shock mount, the taper finish of both is required to be above 12, and the dimensional accuracy is also high. It is best to use a diamond knife to turn.

Introduction to milling slots. The groove shape of the upper and lower shock absorbers can be divided into the back groove and the surface groove, and can be processed on the horizontal milling machine. The horizontal slot milling machine is manual or automatic. The automatic slot milling machine is mainly equipped with automatic feeder and pusher. Through the clamping and cam action of the clamp, the watch automatically sends the workpiece to the milling driven by the motor. The required groove shape is milled out on the knife, and the milling cutter is made of cemented carbide according to the groove size. The machine tool has a simple structure, but only one or two processes can be completed during the machining process. Due to the continuous reform of machine tools and equipment by workers and technicians, a new multi-station milling machine has been successfully trial-produced. It can automatically process the back, groove and chamfer on the shock absorber and automatically check it, distinguishing between the qualified and unqualified parts of the finished product.

Finally, introduce the assembly of the shock absorber. The assembly of the shock absorber is manual. Before assembly, the shock absorber seat, bowl, spring, etc. are first tested by electroplating and finished products. Both the arc hole drill and the support drill should be treated with oil-proof diffusion and then flow into the assembly department. For the mass assembly of the shock absorber, some vibrating discharge tools should be used. Although it is still a manual operation, it is very efficient.