What factors should be considered in selecting the bearing type?
In the mechanism design, it is also troublesome to select the type and specific structure of the bearing. However, if the following factors can be considered clearly and combined with the data in the sample of the bearing manufacturer, the products that meet the use requirements can be selected finally. Common main factors are as follows:
1. Size limit
Generally, the space where bearings can be installed is limited. In most cases, the shaft diameter (or bearing inner diameter) is determined according to mechanical design or other design. Therefore, the selection of bearing type and size is determined according to the inner diameter of the bearing. The main dimension table of standard bearing is compiled according to the international standard inner diameter. There are many dimensions and forms of standard bearing. The use of standard bearing in mechanism design is the most beneficial to the whole equipment.
2. Bearing load
The nature, size and direction of the load applied to the bearing are changeable. In general, the rated base load is shown on the bearing size table. However, radial load and axial load are also important factors in selecting appropriate bearings. For example, when the overall dimensions of ball bearing and roller bearing are equal, roller bearing usually has high bearing capacity and can withstand large vibration and impact load.
3. Rotational speed
The allowable speed is determined according to the type, size, accuracy, cage type, load, lubrication mode, cooling mode and other factors of the bearing. Bearing dimension table The allowable speed of standard precision bearing under oil lubrication and grease lubrication is listed above. Generally, deep groove ball bearings, angular contact ball bearings, self-aligning ball bearings and cylindrical roller bearings are suitable for high-speed operation.
4. Bearing tolerance
Bearing dimensional accuracy and rotation accuracy are based on IS0, GB and JB standards. For machines requiring high precision and high-speed operation, it is recommended to use bearings with accuracy of grade 5 or above (grade 4, grade 2, etc.). Deep groove ball bearings, angular contact ball bearings and cylindrical roller bearings are suitable for occasions with high operation accuracy.
5. Rigidity
When the contact surface of the rolling element and raceway of the bearing is pressed, elastic deformation will occur. Some machines need to minimize elastic deformation. Roller bearings produce less elastic deformation than ball bearings. In addition, in some cases, preloading should be applied to the bearing to increase rigidity. The types of preloading are usually deep groove ball bearings, angular contact ball bearings and tapered roller bearings.
6. The inner and outer rings are not concentric
Shaft bending, change of dimensional tolerance of shaft or bearing housing and improper fit will lead to non concentricity of inner and outer rings. In order to prevent excessive eccentric angle, self-aligning ball bearing, self-aligning roller bearing, self-aligning bearing seat and outer spherical bearing are good choices.
7. Noise and torque
Rolling bearings are manufactured according to high-precision standards, so the noise and torque are small. Deep groove ball bearings and cylindrical roller bearings are suitable for occasions with special requirements for low noise and low torque.
8. Installation and disassembly
Some applications require frequent installation and disassembly to ensure regular inspection and maintenance. The bearings that can be installed separately on the inner and outer rings, such as cylindrical roller bearing, needle roller bearing, tapered roller bearing, etc., are very suitable for this occasion. With the help of shaft sleeve, the installation and disassembly procedures of tapered hole self-aligning ball bearing and self-aligning roller bearing are also simplified.