All types of bearings have different characteristics and are suitable for different applications of various machines. When selecting a bearing type, the following factors should generally be considered. In general, thrust bearings and angular contact bearings are used for thrust loads. For high-speed applications, ball bearings are usually used. When subjected to heavy radial loads, roller bearings are used.https://www.bearingroller.com
Step 1
The space and position of the machine in the bearing In the mechanical design, the size of the shaft is generally determined first, and then the rolling bearing is selected according to the size of the shaft. Ball bearings are usually used for small shafts and roller bearings for large shafts. However,when the bearing is limited in the diameter direction of the machine, needle roller bearings, ultra-light and ultra-light series balls or roller bearings are used; when the bearing is limited in the axial position of the machine, narrow or special can be used. Narrow series of ball or roller bearings.
Step 2
The magnitude, direction and nature of the load on the bearing The load is the most important factor in the selection of the bearing. Roller bearings are used to withstand heavy loads. Ball bearings are used to withstand light or medium loads. Carburized steel or bainite quenched bearings can withstand shock and vibration loads. In the direction of the load, deep groove ball bearings, cylindrical roller bearings or needle bearings can be used when subjected to pure radial loads. Thrust ball bearings are available for small pure axial loads and thrust roller bearings for large pure axial loads. Angular contact ball bearings or tapered roller bearings are generally used when the bearings are subjected to combined radial and axial loads. For cantilever support structures, tapered roller bearings or angular contact ball bearings are often used and used in pairs.
Step 3
The centering performance of the bearing is different when the center line of the shaft is different from the center line of the bearing housing, or the shaft has a small spacing and the rigidity of the shaft is small, and it is easy to be bent or tilted. Self-aligning ball or spherical roller bearings for self-aligning performance, as well as outer ball bearings. These bearings remain functional when the shaft is slightly tilted or bent.
Step 4
Rigidity of the bearing The rigidity of the bearing is the amount of force required to produce a unit deformation of the bearing. The elastic deformation of rolling bearings is very small and can be ignored in most machines. However, in some machines, bearing rigidity is an important factor. Cylindrical and tapered roller bearings are generally used. Because these two types of bearings are subjected to load, their rolling elements and raceways are in point contact and have poor rigidity. In addition, various types of bearings can also be pre-tensioned to achieve the purpose of increasing the rigidity of the support. For example, angular contact ball bearings and tapered roller bearings, in order to prevent the vibration of the shaft and increase the rigidity of the support, a certain axial force is often applied at the time of installation to press them against each other.
Step 5
Bearing speed Each bearing type has its own limit speed, which is determined by physical characteristics such as size, type and structure. The limit speed is the maximum working speed of the bearing (usually r∕min). A limit can cause the bearing temperature to rise, the lubricant to dry out, and even the bearing to jam. The range of speeds required for the application will help determine which type of bearing to use. D is the bearing size, which usually refers to the pitch diameter of the bearing. When selecting the bearing, use the average value of the inner and outer diameter of the bearing in mm. Multiplying the pitch diameter D by the shaft rotation speed (in r/min) yields a limit speed factor (DN), which is important in selecting the bearing type and size. Most bearing manufacturers' catalogues provide limit values for their products. It has been proven that working at temperatures below 90% of the limit speed is better.
Step 6
Bearing travel and axial displacement Normally, a shaft is supported by a distance between two bearings. In order to adapt to the different degrees of thermal rise of the shaft and the outer casing, one bearing should be fixed in the axial direction during installation, and the other bearing can be moved on the shaft (ie, swimming support) to prevent the shaft from being elongated or contracted. The resulting jamming phenomenon. The floating support usually adopts cylindrical roller bearings (formerly 2000 and 32000) with inner or outer ring without ribs and needle bearings. This is mainly because the internal structure of such bearings allows proper axial displacement of the shaft and the outer casing. . At this time, the inner ring and the shaft, the outer ring and the outer casing hole can be tightly fitted. When using non-separable bearings for swimming support, such as deep groove ball bearings, spherical roller bearings, the outer ring and the outer casing hole must be allowed in the installation, or the inner ring and the shaft should be loosely fitted to make the axial direction Free to swim. Tapered roller bearings, spherical roller bearings and deep groove ball bearings are basically of the positioning type, and when used as non-positioning, they are loosely fitted. All thrust roller bearings are positional bearings.
Step 7
Convenient for bearing installation and disassembly When selecting the bearing type, it is convenient to install and disassemble the bearing. It must also be considered comprehensively, especially for the installation and disassembly of large and extra large bearings. The general outer ring separable angular contact ball bearing, tapered roller bearing, cylindrical roller bearing and needle roller bearing are convenient to install and disassemble, and their inner and outer rings can be respectively mounted on the shaft or the housing hole. In addition, spherical roller bearings with inner diameters with tapered bores, adapter sleeves with double sleeves, double row cylindrical roller bearings and self-aligning ball bearings are also easier to install and disassemble.
Step 8
Other requirements In addition to the above factors, the working environment temperature of the bearing, bearing seal and special requirements for friction torque, vibration, noise, etc. should also be considered.