Rolling bearing

Rolling bearing

Compared with sliding bearing, rolling bearing has larger radial size, poor damping capacity, low service life and large sound at high speed. The radial bearing (mainly bearing radial force) in rolling bearing is usually composed of inner ring, outer ring, rolling element and rolling element cage. The inner ring is tightly sleeved on the journal and rotates with the shaft, and the outer ring is installed in the bearing seat hole. A raceway is arranged on the outer circumference of the inner ring and the inner circumference of the outer ring. When the inner and outer rings rotate relative to each other, the rolling elements roll on the raceway of the inner and outer rings. They are separated by a cage to avoid mutual friction. The thrust bearing is divided into two parts: tight ring and movable ring. The tightening ring is tight with the shaft sleeve, and the movable ring is supported on the bearing seat. The ring and rolling element are usually made of rolling bearing steel with high strength and good wear resistance. The surface hardness after quenching shall reach HRC60 ~ 65. The cage is mostly made of mild steel, or copper alloy cloth, bakelite or plastic.

There are many kinds of rolling bearings, as follows:

According to the bearing direction, it can be divided into radial bearing (bearing radial force and small axial force), thrust bearing (only bearing axial force) and radial thrust bearing (bearing radial force and axial force at the same time).

According to the shape of rolling element, it can be divided into ball bearing, roller bearing and needle roller bearing.

According to the working conditions, it can be divided into ordinary bearing, high-speed bearing, high-temperature bearing, low-temperature bearing, vacuum bearing, antimagnetic bearing, corrosion-resistant bearing, precision micro bearing and super large bearing. In China, various types of rolling bearings are divided into five accuracy levels: B, C, D, e and g. B is the high accuracy level and G is the ordinary accuracy level, which is widely used.

Rolling bearings are standard parts, which are produced in batches by special bearing factories. Factors to be considered in design selection include service life, load, accuracy, clearance (radial and axial), speed, friction torque, centering performance, preload and rigidity, vibration and noise, etc.

Compared with sliding bearing, rolling bearing has many advantages

Under normal conditions, the efficiency of rolling bearing is equivalent to that of hydrodynamic bearing, but higher than that of hybrid bearing;

The radial clearance is relatively small, and the centripetal angular contact bearing can be preloaded, and the clearance can be eliminated by preload, with high operation accuracy;

The radial clearance is relatively small, and the centripetal angular contact bearing can be preloaded, and the clearance can be eliminated by preload, with high operation accuracy;

Most rolling bearings can be subjected to radial and axial loads at the same time, so the bearing combination structure is simple;

Low lubricant consumption, easy sealing and maintenance;

There is no need for useful non-ferrous metals;

High degree of standardization, batch production and low cost.

Compared with plain bearings, rolling bearings have the following disadvantages:

Poor ability to bear impact load;

Bearing life is low under high speed and heavy load;

Large vibration and noise;

Radial dimension ratio plain bearing.