The spherical roller bearing consists of a drum-shaped roller that is positioned between an inner ring with two raceways and an outer ring with a spherical race.
Spherical roller bearings are designed to handle both radial and axial loads, with a higher capacity for radial loads. They are particularly suitable for heavy loads or those subjected to vibration, but not for pure axial loads.
The outer ring of the spherical roller bearing has a spherical raceway, providing excellent self-aligning performance and the ability to compensate for coaxiality errors. The bearing features two rows of symmetrical spherical rollers, with an outer ring that has a common spherical raceway and an inner ring that has two raceways inclined at an angle to the bearing axis. This design provides good alignment performance.
Even if the shaft is bent or installed with different cores, the spherical roller bearing can still function properly. The allowable centering angle varies depending on the bearing size series, with a typical range of 1 to 2.5 degrees.
Overall, this type of bearing has a large load capacity, making it a popular choice for various applications.
In addition to radial load capacity, spherical roller bearings are also capable of withstanding axial loads in both directions and have good impact resistance. They also typically have lower operating speeds compared to other bearings.
The spherical roller bearing is divided into two structures: symmetrical and asymmetrical, based on the shape of the roller section. Asymmetrical spherical roller bearings were developed earlier and were mainly used for maintenance purposes, while symmetrical spherical roller bearings are less commonly used in new equipment design.
The design and parameters of the symmetrical spherical roller bearing have been improved, allowing for greater axial load capacity compared to earlier versions. This type of bearing also has a lower operating temperature and can accommodate higher speed requirements.
In terms of inner ring design, spherical roller bearings can be divided into two types: C and CA. The C-type bearing has an inner ring without a rim and uses a stamped steel plate holder, while the CA-type bearing has a rib on both sides of the inner ring and a solid body cage.
To improve the lubrication of the spherical roller bearing, an annular oil groove and three oil holes in the outer ring can be provided, which is indicated by the code /W33. Bearings with inner ring oil holes are also available upon request.
For easy installation and replacement, tapered roller bearings with an inner bore are also available. The taper is 1:12 and is indicated by the code K. A taper of 1:30 is also available for special user requirements, indicated by the code K30.
The tapered inner bore bearing can be mounted directly onto a tapered journal with a lock nut, or it can be mounted onto a cylindrical journal with the use of an adapter sleeve or withdrawal sleeve.
It is important to note that to prevent harmful slippage between the raceway and roller due to high-speed centrifugal action, the bearing must withstand a minimum radial load. The size of the minimum radial load can be estimated as follows:
Fr = 0.02C
In the formula:
Fr — minimum radial load N
C—the basic dynamic load rating of the bearing N
Equivalent dynamic load
P=Fr+Y1Fa when Fa/Fr e
P=0.67Fr+Y2Fa when Fa/Fr e
In the formula:
P-equivalent dynamic load N
Y1 Y2—Axial dynamic load factor
Equivalent static load
P0=Fr+Y0Fa
In the formula:
P0 – equivalent static load N
Y0—axial static load factor
Applications
Mainly applicable cages:
- Stamped steel plate reinforced cage (suffix E)
- Stamped steel plate cage (suffix CC)
- Glass fiber reinforced polyamide 66 cage (suffix TVPB)
- Machined brass two-piece cage (suffix MB)
- Machined brass integral cage (suffix CA)
- Stamped steel plate cage for vibration occasions (suffix JPA)
- Brass cage for vibration applications (suffix EMA)
Even for the same structure, the code on the bearing may be different.
The main application:
- Paper machine
- Speed reducer
- Railway vehicle axle
- Rolling mill gearbox housing
- Rolling mill roller
- Crusher
- Vibrating screen
- Printing machines
- Woodworking machinery
- Various industrial speed reducers
- Vertical belt bearing
Installation
The spherical roller bearing consists of a drum-shaped roller positioned between an inner ring with two raceways and an outer ring with a spherical race.
The center of curvature of the outer raceway surface is aligned with the center of the bearing, allowing for the same self-aligning capabilities as a self-aligning ball bearing. When the shaft and outer casing experience deflection, the bearing is able to automatically adjust for axial loads in both directions.
This type of bearing has a large radial load capacity, making it suitable for heavy loads and impact loads. The inner diameter of the inner ring is a tapered bore, which allows for direct mounting or mounting using an adapter sleeve or removal cylinder on a cylindrical shaft.
The cage of the spherical roller bearing can be made from steel stamping, polyamide, or copper alloy. In addition, for self-aligning bearings, an intermediate mounting ring helps to prevent the outer ring from tilting and rotating when the bearing is inserted into a housing shaft hole.
It is important to note that some sizes of self-aligning ball bearings have balls that protrude from the sides of the bearing. In this case, the intermediate mounting ring should be recessed to protect the balls from damage.
Many bearings are typically installed using mechanical or hydraulic methods. For detachable bearings, the inner and outer rings can be installed separately, which simplifies the installation process, especially when an interference fit is required between the inner and outer rings.
When inserting a shaft with the inner ring already in place into a bearing housing that contains the outer ring, it is important to carefully ensure that the inner and outer rings are properly centered to avoid damaging the raceways and rolling elements.
For cylindrical and needle bearings fitted with an inner ring without flange ribs or with flanged sides on one side, it is recommended to use a mounting sleeve. The outer diameter of the sleeve should match the inner ring raceway diameter F and have a tolerance for machining of d10.
Drawn cup needle roller bearings are best mounted using a mandrel.
Clearance
The axial clearance of the spherical roller bearing can be adjusted using an adjusting nut on the journal, adjusting washer and thread in the bearing housing hole, or by using a pre-tightening spring. The size of the axial clearance depends on factors such as the arrangement of the bearing when installed, the distance between bearings, and the material of the shaft and bearing housing, and can be determined based on the operating conditions.
For high-load, high-speed spherical roller bearings, the impact of temperature rise on the axial clearance must be considered when adjusting the clearance. The amount of clearance reduction caused by temperature rise should be estimated and the axial clearance should be adjusted to be slightly larger.
For bearings operating at low speeds and with low vibration, no clearance or preload installation is required. This ensures good contact between the roller and raceway and evenly distributes the load, preventing damage to the roller and raceway due to vibration.
After adjusting, the size of the axial clearance can be checked using a dial gauge. The dial gauge is first fixed to the body or bearing seat, so that it contacts the smooth surface of the shaft. The shaft is then pushed along the axial direction, and the maximum swing of the hands on the dial gauge is the axial clearance value.
