Difference and concept between shock absorber and vibration isolator
A shock absorber is the main means to prevent vibration hazards in engineering. The wire rope shock absorber can be divided into active shock absorber and passive shock absorber. The active vibration damper is designed to eliminate the vibration source or reduce the energy or frequency of the vibration source. It is widely used in precision instruments, aerospace equipment, large steam turbine generator units and high-speed rotating machinery, but it is expensive and less used in common construction machinery. Passive shock absorbers include vibration isolators and absorbers. The wire rope vibration isolators can be divided into active isolator and passive isolator.
In order to prevent or limit the harm and influence caused by vibration, various measures are adopted in modern engineering, which is summarized as follows:
- Reduce or eliminate the vibration source (active shock absorber)
This is a positive fundamental measure. If the vibration is caused by the eccentricity of the rotating parts, the unbalanced centrifugal inertia force can be reduced by improving the dynamic balance accuracy. For reciprocating machinery such as air compressor, attention should also be paid to the balance of inertia force.
- Keep away from a vibration source (passive vibration isolator)
This is a negative protective measure. For example, precision instruments or equipment should be as far away as possible from factories or workshops with large power machinery, pressure processing machinery and vibration machinery, as well as railways and highways with busy transportation.
- Improve the anti-vibration ability of the machine itself (active shock absorber)
The commonly used index to measure the anti-vibration ability of the machine structure is the dynamic stiffness, which is equal to the dynamic force required by the unit amplitude of the machine structure. The larger the dynamic stiffness, the smaller the vibration of the machine structure under the dynamic force.
- Avoid resonance area
Change the natural frequency of the system (active damper) or the working speed of the machine (passive damper) as much as possible according to the actual situation, so that the machine does not work in the resonance area.
- Increase damping appropriately (damping and vibration absorption)
Damping absorbs the vibration energy of the system and makes the amplitude of the free vibration attenuate rapidly. It can restrain the amplitude of the forced vibration, especially in the resonance region.
- Dynamic vibration absorption (passive vibration absorption)
For measuring or monitoring instruments on some equipment, the method of installing dynamic vibration absorber under the instrument can stabilize the pointer of the instrument and improve the measurement accuracy.
- Take wire rope vibration dampersmeasures
Using elastic vibration isolator to isolate the vibrating machine (vibration source) from the foundation, so as to reduce the vibration source to affect the surrounding equipment through the foundation, which is the active vibration isolator or active vibration isolator; or isolating the precision equipment to be protected from the impact of the surrounding vibration source, which is the passive vibration isolator.
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