What Is an Anti-Vibration Mount?
Anti-vibration mounts are designed to suppress the transmission of vibrations from equipment that generates vibrations to the outside, such as at manufacturing sites where fine processing is required or in situations where precision optical experiments are conducted.
Conversely, a vibration isolator suppresses vibration transmitted externally.
The performance of an anti-vibration mount is determined by the natural frequency of the mount itself. The lower the natural frequency, the less the anti-vibration mount can follow the vibration from the surroundings, and thus the higher the anti-vibration mount’s performance.
Air springs are often used to realize such a mount, which can provide anti-vibration mounts not only in the horizontal direction but also in three dimensions.
The viscous resistance of air damps vibrations quickly.
Uses of Anti-Vibration Mounts
Anti-vibration mounts are often used in the manufacture of precision equipment, such as semiconductors and liquid crystal displays, which are vibration sensitive, by means of vibration reduction using air springs.
Anti-vibration mounts are particularly useful when pumps, machine tools, and other equipment that generate vibration are used on a stand to suppress the transmission of vibration to the outside.
In the case of measurement using a precision instrument, the vibration of the tabletop during work or from external sources can be quickly suppressed, thereby improving the efficiency of the measurement time.
Most anti-vibration mounts can be used for both anti-vibration and anti-shock (elimination of external vibrations).
Principle of Anti-Vibration Mounts
Vibration isolation is the process of suppressing as much as possible the vibration transmitted from a vibrating machine or other vibrating object.
Vibrations transmitted through gases are greatly attenuated by obstacles along the way, so they are not transmitted very far.
In the case of solids, however, the solid acts as a medium and propagates the vibration, making control of the vibration very important.
To suppress the propagation of vibrations in a solid, the frequency at which the solid is inherent (natural frequency) must be controlled. If a solid has a natural frequency that is the same as the frequency of the propagating vibration, it will vibrate violently.
Therefore, the propagation of vibration can be reduced by making the frequency of propagation and the natural frequency as far apart as possible.
In particular, the smaller the natural frequency, the lower the rate of vibration transmission, which is why anti-vibration mounts are equipped with air springs or coil springs. The natural frequency is as low as 10 Hz or less.
In the air spring method, compressed air is filled into an air spring consisting of metal fittings and a rubber membrane. The air supply is used to maintain the level of the platform.
On the other hand, the coil spring method has the advantage of not requiring air, but has the disadvantage that the spring deflects and tilts when the center of gravity of the mounted object moves.