Introduction of bearings

Bearings are components that fix, rotate and reduce the friction coefficient of loads during mechanical transmission. It can also be said that when other parts move relative to each other on the shaft, it is used to reduce the friction coefficient during the transmission of motion force and keep the center position of the rotating shaft fixed.

Bearings are an important part of modern mechanical equipment. Its main function is to support the mechanical rotating body to reduce the mechanical load friction coefficient of the equipment during the transmission process. Its accuracy, performance, life and reliability play a decisive role in the accuracy, performance, life and reliability of the main engine. . According to the different friction properties of moving parts, bearings can be divided into rolling bearings and sliding bearings.

Bearing parameters

life

Under a certain load, the number of revolutions or hours experienced by the bearing before pitting occurs is called the bearing life.

The life of rolling bearings is defined by the number of revolutions (or the number of hours of work at a certain speed): bearings within this life should have initial fatigue damage (flaking or defect) on any of their bearing rings or rolling elements. However, no matter in the laboratory test or in actual use, it can be clearly seen that the actual life of bearings with the same appearance under the same working conditions is quite different. In addition, there are several different definitions of bearing "life", one of which is the so-called "operating life", which indicates that the actual life a bearing can achieve before failure is caused by wear, damage is usually not caused by fatigue, but Caused by wear, corrosion, seal damage, etc.

In order to determine the standard of bearing life, the bearing life is related to the reliability.

Due to the difference in manufacturing precision and material uniformity, even the same batch of bearings of the same material and size are used under the same working conditions, and their service life is not the same. If the statistical life is 1 unit, the longest relative life is 4 units, the shortest is 0.1-0.2 units, and the ratio of the longest to the shortest life is 20-40 times. 90% of the bearings do not produce pitting, and the number of revolutions or hours experienced is called the bearing rating life.

Rated dynamic load

In order to compare the bearing capacity of the bearing against pitting corrosion, when the rated life of the bearing is specified as one million revolutions (106), the maximum load it can bear is the basic rated dynamic load, expressed in C.

That is to say, under the action of the rated dynamic load C, the reliability of this kind of bearing working for one million revolutions (106) without pitting failure is 90%, and the greater the C, the higher the carrying capacity.

For basic dynamic load rating

1. Radial bearing refers to pure radial load

2. Thrust ball bearings refer to pure axial load

3. Centripetal thrust bearing refers to the radial component that produces pure radial displacement

Detailed meaning of bearing model

1. Bearing type meaning, bearing type code, comparison table of commonly used type codes for imported bearings (referring to numbers or letters at the beginning of the model, such as deep groove ball bearings starting with 6200, 6, cylindrical roller bearings starting with NU, NJ) 3360 self-aligning Ball bearing-1; Self-aligning roller bearing-2; Tapered roller bearing-3; Thrust ball bearing-5 Deep groove ball bearing-6; Angular contact ball bearing-7; Cylindrical roller bearing-n; Needle roller bearing -North America.

2. The two digits on the right represent the nominal inner diameter of the bearing. When the inner diameter is in the range of 20~480MM, the inner diameter multiplied by 5 is the inner diameter of 10~17. Please refer to the bearing manual. The third digit on the right is the diameter series code: the diameter series codes are 7, 8, 9, 0, 1, 2, 3, 4, 5, etc. The fourth digit from the right is the width series code, use 8,0. Bearings of the same type have the same inner diameter, larger outer diameter (outer diameter, width), and stronger load-carrying capacity.

3. The fifth digit from the right indicates the type of bearing, which is a part used to reduce the friction coefficient and fix the center position of the shaft in mechanical movement. Can be divided into sliding bearings and rolling bearings. The meaning of bearer type includes basic code and supplementary code. The code basically represents the information of the bearing structure, size and type. Supplementary codes are mainly codes added when some information changes. In addition, the preamble is on the left side of the basic code, and the postamble is on the right side of the basic code. Therefore, in the query of the bearing model, you must first figure out the meaning of the bearing model represented by various letters.