Vibration Isolator: Types and Applications

Catalog

I. Types

1. Metal Rubber Vibration Isolator

Metal rubber is a simulation product of natural rubber. The metal rubber component is made of metal wire and does not contain any natural rubber, but it has the same elasticity and porosity as natural rubber. It is especially suitable for solving high and low temperature, large temperature differences, high pressure, and high vacuum. The inside is a network, similar to the macromolecular structure of natural rubber. Under the action of alternating stress and strain, a large amount of vibration energy is dissipated. The damping in the resonance zone is significantly increased, which can effectively suppress the resonance peak. In the vibration isolation zone, the internal damping decreases rapidly, so it has excellent damping characteristics, with a damping ratio of 0.2 to 0.3.

Its stiffness characteristic also presents a linear-soft characteristic-hard characteristic non-linear characteristic with increasing amplitude. That is, the effect of gradually softening stiffness appears, which will reduce the "natural frequency" of the system's spatial direction. As the magnitude of the external excitation increases, the "natural frequency" of this product decreases, so it has a good vibration isolation effect; it can be said that metal rubber is a loose structure material with high elasticity and good damping characteristics, and its density is only metal About 0.3.

Because the metal rubber material can withstand high temperature, high pressure, high vacuum, and ultra-low temperature, it does not evaporate in the space environment and is not afraid of space radiation and particle impact. The metal rubber component has the characteristics of long storage and long service life, and no aging phenomenon. For example, because the damping material of the bridge damping bearing is made of natural rubber, it is conceivable that the replacement engineering amount and economic loss caused by the failure of aging can be imagined. And the working temperature of natural rubber is -40°C～60°C and the working temperature of metal rubber is -150°C～+360°C, its advantages are obvious.

Therefore, various components made of it can not only work in the above-mentioned harsh environment, but also maintain very good properties in this environment, and can meet the special needs of spacecraft for national defense and some special working environments. Special requirements for component materials.

Vibration damping and vibration isolation components made of metal rubber are characterized by small size and lightweight. They can be made into a variety of vibration isolators and are suitable for vibration damping and isolation of various electronic instruments, power equipment, and pipelines. It is especially suitable for hostile environments such as aviation, aerospace, navigation, and the chemical industry.

2. Steel Spring Vibration Isolator

From equipment weighing hundreds of tons to lightweight precision instruments, steel spring isolators can be applied. They are usually used where static compression is greater than 5 cm or where temperature and other environmental conditions do not allow the use of rubber and other materials.

The advantages of this type of vibration isolator are 1. Large static compression, low natural frequency, and good low-frequency vibration isolation; 2. Resistance to corrosion by oil, water, and solvents, and not affected by temperature changes; 3. No aging or creep; 4. The characteristics change little when mass production.

Its disadvantages are 1. The damping is very small (the damping ratio is about 0.005), so that the transmission rate is very large at resonance; 2. It is easy to transmit vibration along the steel wire at high frequency; 3. It is easy to produce rocking motion, so external damping (such as metal Silk, rubber, felt, etc.) and inert blocks. Steel springs have spiral, disc, ring, and plate shapes, and spiral springs are the most widely used. After the natural frequency is given, the vertical stiffness K of a single spring is calculated (N/m is Newton per meter). The TJ1 spiral steel spring vibration isolator made in China has a load of 17～1020 kg, a natural frequency of 3.5～2.2 Hz, and a static compression of 20～52 mm.

3. Rubber Vibration Isolator

The main design parameters of rubber vibration isolators are used as the rubber of vibration isolators. They require good vibration isolation, buffering and noise reduction capabilities, stable performance, long service life, easy to form the required shape, and strong adhesion to metal. The area bearing capacity is large. It can be used for cutting, compressing, or cutting pressure, and it is rarely used for tension. Its advantage is: it can be made into various shapes and different stiffness. Its internal damping effect is greater than that of steel springs, and it can isolate the excitation frequency as low as about 10 Hz. The disadvantage is that it will age after a long time of use, and there will be greater creep under heavy load (especially at high temperatures), so it should not be subjected to more than 10-15% (compression) or 25-50% (shear) Continuous deformation.

The natural frequency of natural rubber is slightly lower than that of synthetic rubber. Its mechanical properties are small change, large tensile force, long elongation when damaged, and low price, but it cannot be used in contact with oils, hydrocarbons, and ozone. Places with high equipment and ambient temperature. Neoprene and nitrile rubber isolators have good resistance to hydrocarbons and ozone, and nitrile rubber isolators can also adapt to high temperatures. Silicone rubber vibration isolator can be used in low temperature or high temperature (-75℃ to +200℃) environment where other materials cannot handle.

II. Applications

1. Vibration Isolator Pad

Vibration isolator pads include cork, felt, rubber pads, and glass fiberboards. The advantages are: low price, easy installation, and can be cut to the required size and overlapped for use to obtain different degrees of vibration isolation effects.

Metal rubber vibration isolator pads use metal wire as raw material, do not contain any ordinary rubber, but have the same elasticity and porosity as rubber. It is especially suitable for solving high and low temperature, large temperature difference, high pressure, high vacuum, strong radiation, severe vibration and Difficult problems such as damping and vibration reduction, filtration, sealing, throttling, sound absorption and noise reduction in corrosion and other environments can be prepared in various structural shapes according to different working conditions. Moreover, it has the characteristics of long storage, long service life, and no aging phenomenon. It is the best substitute for ordinary rubber under special working conditions of aerospace, national defense weapon equipment, and civilian products.

The advantages of metal rubber vibration isolator pads:

①Using metal wire as raw material, it does not contain any ordinary rubber, but it has the same elasticity and porosity as rubber.

②Resistance to high and low temperature, large temperature difference, high vacuum, strong radiation, and corrosive environment.

③High carrying capacity, fatigue resistance, no aging phenomenon, long service life, and storage time.

④It can meet the needs of damping, vibration reduction, sealing, filtering, throttling and sound absorption, and noise reduction. It is the best substitute for ordinary rubber products and other porous material products under special industrial and mining.

⑤Its performance indicators can be designed, and by changing different process parameters and methods, metal rubber products with different structural sizes and performance characteristics can be prepared.

⑥It is suitable for various fields such as aerospace, missile ship, starship, national defense weapons and equipment, petrochemical industry, and automobile industry, with distinctive features of both military and civilian use.

2. Steel Vibration Isolation Base

The machine is sometimes installed on a vibration isolation base, which is usually made of concrete or steel. The use of heavy and rigid concrete inert blocks can increase the effective weight of the load-bearing machine, and its functions are:

①Reduce vibration and reduce the effect of machine unbalanced force;

②Improve the force resistance and make the machine installation firm;

③Reduce the center of gravity and increase stability;

④ Reduce the natural frequency.

The weight of the inert block should be at least equal to the weight of the machine, preferably twice the weight of the machine. Reciprocating engines and compressors usually require a base of 3 to 5 times the weight, while light machines sometimes require a base that is 10 times the weight of the machine.