2022 November the Four Week GQZ Technical Knowledge: Several factors to be considered in the selection of rolling bearings
Hot tags: gqz deep groove ball bearing(1)
"Various types of bearings have different characteristics due to their different designs. Due to the variability and complexity of the specific installation positions and applications of the bearings, there is no fixed mode to choose the bearing type. In order to adapt to the specific installation positions and application conditions of a certain host, it is recommended to comprehensively consider the following main factors when selecting the bearing type."
In mechanical design, the size of the shaft is generally determined first, and then the bearing is selected according to the size of the shaft. Generally, ball bearings are used for small shafts; Cylindrical roller bearing, self-aligning roller bearing and tapered roller bearing (sometimes ball bearing can also be used) are selected for the main shaft. If the radial space of the bearing installation position is limited, the bearing with smaller radial section height shall be used. Such as needle roller bearings, some series of deep groove ball bearings, angular contact ball bearings, cylindrical roller or self-aligning roller bearings and thin-walled bearings. If the axial space of the bearing installation position is limited, the bearing with smaller width can be used.
The size of the load is usually the determining factor in selecting the bearing size. The bearing capacity of roller bearing is greater than that of ball bearing with the same overall dimension. Generally, ball bearings are suitable for light or medium loads, and roller bearings are suitable for heavy loads.
In terms of load mode, deep groove ball bearing and cylindrical roller bearing can be selected for pure radial load; Thrust ball bearing and thrust cylindrical roller bearing can be selected for pure axial load; When there is radial load and axial load (combined load), angular contact ball bearings or tapered roller bearings are generally selected. If the radial load is large and the axial load is small, deep groove ball bearing and cylindrical roller bearing with rib in inner and outer rings can be selected. In the same case, the shaft or housing is deformed greatly and the installation alignment is poor, so the self-aligning ball bearing and self-aligning roller bearing can be selected. If the axial load is large and the radial load is small, thrust angular contact ball bearing and four point contact ball bearing can be selected; If self-aligning performance is also required, thrust self-aligning roller bearing can be selected.
The working speed of rolling bearing mainly depends on its allowable operating temperature. Bearings with low friction resistance and less internal heat are suitable for high-speed operation. When only bearing radial load, deep groove ball bearing and cylindrical roller bearing can achieve higher speed. If bearing combined load, angular contact ball bearing should be selected. High precision angular contact ball bearing with special design can achieve extremely high speed. The speed of all thrust bearings is lower than that of radial bearings.
For most machines, the use of bearings with Class 0 tolerance is sufficient to meet the requirements of the host machine, but when there are strict requirements on the rotation accuracy of the shaft, such as machine tool spindles, precision machinery and instruments, the use of deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings and thrust angular contact ball bearings with higher tolerance levels should be selected.
The rigidity of a rolling bearing is determined by the elastic deformation that occurs when it bears a load. Generally, this deformation is small and can be ignored. However, in some machines, such as machine tool spindle systems, the static and dynamic stiffness of the bearing has a great impact on the characteristics of the system. Generally speaking, roller bearings have higher stiffness than ball bearings. All kinds of bearings can also improve the rigidity to varying degrees through proper "pre tightening".
Vibration and noise
The noise and vibration of the bearing itself are generally very low. However, for small and medium-sized motors, office machinery, household appliances and instruments that have special requirements on noise and running stability, low-noise bearings are usually selected.
The most common configuration of bearings is to install a set of axially positioned "fixed bearings" at one end of the shaft and a set of axially movable "floating bearings" at the other end to prevent the shaft from being stuck due to thermal expansion and cold contraction. The frequently used "floating bearing" is a cylindrical roller bearing with no rib on the inner or outer ring. At this time, the interference fit can be used for the fit between the inner ring and the shaft or the fit between the outer ring and the shell hole. Sometimes, non separable deep groove ball bearings or self-aligning roller bearings can also be selected as floating bearings. However, clearance fit shall be selected for the fit between the inner ring and the shaft or the outer ring and the housing hole during installation to ensure that the inner ring or outer ring has enough freedom of axial movement.
The friction resistance of ball bearing is smaller than that of roller bearing, and the friction resistance of radial contact bearing is smaller under pure radial load; Under pure axial load, the friction resistance of axial contact bearing is small; When the combined load is applied, the friction resistance of angular contact bearing with the bearing contact angle close to the load angle is the minimum. In the instruments and machinery that need low friction torque, ball bearings or cylindrical roller bearings are more appropriate. In addition, contact seals should be avoided for low friction torque bearings. At the same time, drip lubrication, oil air lubrication or other lubrication methods conducive to wear reduction are recommended.
Installation and removal
Bearings with cylindrical inner holes are used in machinery with frequent installation and disassembly. Separate angular contact ball bearings, tapered roller bearings, separable cylindrical roller bearings, needle roller bearings, thrust bearings, etc. shall be preferred. The bearing with conical bore can be installed on the journal, or it can be installed on the cylindrical journal with the help of a set sleeve or a withdrawal sleeve, which is more convenient for installation and removal.
More about GQZ Deep Groove Ball Bearing:
Deep groove ball bearing is one of the most widely used rolling bearings. It is characterized by low friction resistance and high speed. It can be used for parts bearing radial load or combined load of radial and axial at the same time. It can also be used for parts bearing axial load, such as small power motor, automobile and tractor gearbox, machine tool gearbox, general machines, tools, etc.
Features of deep groove ball bearing:
1.Each groove of the bearing has a circumference of about 1/3 of the continuous groove. It is mainly used to bear radial load and certain axial load.
2. when the radial clearance of the bearing increases, it has the property of angular contact ball bearing and can bear the alternating axial load in two directions.
3. low friction and high speed.
4. simple structure, low manufacturing cost and easy to achieve high manufacturing accuracy.
5. generally, stamping wave cage is adopted. For bearings with inner diameter greater than 200mm or high-speed operation, turning solid cage is adopted.
There are more than 60 variant structures of deep groove ball bearings.
Founded in 1999, Wuxi Guangqiang Bearing Trade Co.,LTD, deals with precision bearings and bearing related products across a large spectrum of customers. Since the founding the company, we keep standing by the principle of "Quality First, Credit First, Independent Innovation" and our company has won a great reputation from home and abroad.