What are the methods to reduce the noise of imported bearings

(1) Methods of using chemical additives

Adding certain chemical additives to the lubricant of imported bearings can reduce the noise of imported bearings. For example, a low-noise grease containing noise reducing additives produced by a factory in Tianjin can reduce the noise of imported bearings by 3.9-9.2dB from the original level, making it suitable for use in micro or small imported bearings.

(2) Use vibration absorption or isolation devices

The use of vibration absorption or isolation devices to reduce or isolate the noise of imported bearings can achieve good results, but this often comes at a great economic cost, sometimes causing the mechanism to become larger, the heat dissipation conditions to deteriorate, or it is easy to rust. Therefore, comprehensive consideration should be given when using this method, and it should only be used after other measures have been taken but still cannot achieve the low noise index.

A simple example is the radial ball inlet bearing that replaces the thrust inlet bearing and bears thrust at high speeds. A plastic jacket filled with rust proof lubricating oil can be placed on its outer ring. The thrust inlet bearing with a cover or a general thrust inlet bearing can be fitted with the same plastic jacket in its inner hole or outer circle if allowed, but it should not rub or interfere with adjacent components during rotation. This method has a certain soundproofing effect.

Another example is to add an intermediate sleeve between the imported bearing and the seat hole, which can attenuate the vibration force transmitted by the rotating system to the imported bearing seat. However, this requires proper adjustment, otherwise the opposite effect may occur.

Another example is to use a sound-absorbing and soundproof enclosure to completely or as tightly seal the inlet bearing system that generates noise as possible. The interior of the noise reduction hood is glass fiber or polyurethane foam plastic. The inner surface is a steel plate with a thickness of 0.6-lmm. The surface is evenly distributed with φ 1.2-1.5mm small through holes. The total area of the holes accounts for about 25%~30% of the entire inner surface. The outer surface is a steel plate with a thickness of 2mm. Here, glass fiber or foam plastic is used to eliminate noise at higher frequencies, the inner surface with holes is used to eliminate noise at lower frequencies, and the thick steel plate on the outer surface is used to isolate the external transmission of noise.

(3) Method of changing the rotational speed of the corresponding part of the host

The noise of imported rolling bearings is not very sensitive to the load, but it is very sensitive to the speed. If conditions permit, the method of reducing the speed and increasing the torque can achieve the same working purpose, but it reduces the noise.