Tapered roller bearing is a separate type bearing, the inner and outer rings of the bearing have tapered raceway. This kind of bearing can be divided into single row tapered roller bearing, double row tapered roller bearing and four row tapered roller bearing. Single row tapered roller bearing can bear radial load and single direction axial load. When the bearing bears the radial load, it will produce an axial force component, so when it needs another bearing which can bear the opposite axial force to balance.
brief introduction
Tapered roller bearing is a kind of radial thrust rolling bearing whose rolling element is tapered roller. There are small cone angle and large cone angle. The small cone angle mainly bears the radial and axial combined load dominated by the radial load, which is often used in pairs and installed in reverse direction. The inner and outer seat rings can be installed separately, and the radial and axial clearance can be adjusted during the installation and use; the large cone angle mainly bears the axial and radial combined load dominated by the axial load, which is generally not used to bear the pure axial load alone, but as a pair configuration (the same name end is opposite) It can be used to bear pure radial load.
definition
The axial load bearing capacity of single row tapered roller bearing depends on the contact angle, that is, the outer ring raceway angle. The larger the angle is, the greater the axial load capacity is. Single row tapered roller bearing is the most widely used tapered roller bearing. In the front wheel hub of a car, a small size double row tapered roller bearing is used. Four row tapered roller bearings are used in large cold and hot rolling mills and other heavy machines.
Structural features
The type code of tapered roller bearing is 30000, and the tapered roller bearing is a separate type bearing. In general, especially in GB / t307.1-94 "rolling bearings radial bearing tolerances" involved in the size range of tapered roller bearing outer ring and inner components are 100% interchangeable.
The angle of the outer ring and the diameter of the outer raceway have been standardized as the overall dimensions. It is not allowed to change during design and manufacture. So that the outer ring and inner assembly of tapered roller bearing can be interchanged in the world.
Tapered roller bearing is mainly used to bear radial and axial combined load which is mainly radial load. Compared with angular contact ball bearing, the bearing capacity is large and the limit speed is low. Tapered roller bearing can bear axial load in one direction and limit axial displacement of shaft or shell in one direction.
classification
The single row tapered roller bearing has an outer ring, and its inner ring and a set of tapered rollers are an inner ring assembly enclosed by a basket cage. The outer ring can be separated from the inner ring assembly. According to the requirements of ISO tapered roller bearing dimension standard, the outer ring or inner ring assembly of any standard model of tapered roller bearing should be internationally interchangeable with the outer ring or inner ring assembly of the same model. That is to say, the external dimension and tolerance of the outer ring of the same model shall comply with the provisions of iso492 (gb307), and the cone angle and cone diameter of the inner ring assembly shall also comply with the relevant provisions of interchangeability.
Generally, the taper angle of outer ring raceway of single row tapered roller bearing is between 10 ° and 19 ° and can bear the combined action of axial load and radial load at the same time. The larger the cone angle, the greater the ability to bear the axial load. The bearing with large taper angle, with rear code and B, has a taper angle between 25 ° and 29 ° and can bear large axial load. In addition, the single row tapered roller bearings can adjust the clearance size during the installation process.
The outer ring (or inner ring) of double row tapered roller bearing is a whole. The small end faces of two inner rings (or outer rings) are close, and there is a spacer in the middle. The clearance is adjusted by the thickness of the spacer, and the thickness of the spacer can also be used to adjust the pre interference of double row tapered roller bearings.
Four row tapered roller bearing, the performance of this kind of bearing is basically the same as that of double row tapered roller bearing, but it bears greater radial load than double row tapered roller bearing, and its limit speed is slightly lower, so it is mainly used in heavy machinery.
ZWZ provides long life, multi seal double and four row tapered roller bearings. In order to improve the sealing effect and improve the sealing performance, a new type of sealing structure combining sealing with dust prevention is adopted. Compared with the open structure bearing, the service life of multi seal double row and four row tapered roller bearing is increased by 20% ～ 40%, and the lubricant consumption is reduced by 80%.
purpose
Tapered roller bearings mainly bear the radial and axial combined load. The bearing capacity depends on the raceway angle of the outer ring, and the larger the angle is, the better the bearing capacity is
The greater the load carrying capacity. According to the number of rolling elements in the bearing, it can be divided into single row, double row and four row tapered roller bearings. The clearance of single row tapered roller bearing needs to be adjusted by the user during installation; the clearance of double row and four row tapered roller bearing has been given according to the user's requirements when the product leaves the factory, so it does not need to be adjusted by the user.
Tapered roller bearings have tapered inner ring and outer ring raceways, and tapered rollers are arranged between them. The projection lines of all conical surfaces converge at the same point of the bearing axis. This design makes tapered roller bearings particularly suitable for compound (radial and axial) loads. The axial load capacity of the bearing is mostly determined by the contact angle α; the larger the angle α is, the higher the axial load capacity will be. The angle is expressed by the calculation coefficient E; the larger the value of E is, the larger the contact angle is, and the greater the applicability of bearing under axial load is.
Tapered roller bearings are usually separated, that is, the tapered inner ring assembly composed of roller and cage assembly can be installed separately from the tapered outer ring (outer ring).
Tapered roller bearings are widely used in automobile, rolling mill, mining, metallurgy, plastic machinery and other industries.
install
The following information is provided by the complete selection of fast easy automation.
Adjust the axial clearance. For the installation of tapered roller bearings, the axial clearance can be adjusted by adjusting the nut on the journal, adjusting the gasket and the thread in the bearing seat hole, or by preloading the spring. The size of the axial clearance is related to the arrangement of the bearings, the distance between the bearings and the material of the shaft and the bearing seat, which can be determined according to the working conditions.
For tapered roller bearings with high load and high speed, the influence of temperature rise on the axial clearance must be considered when adjusting the clearance, and the clearance reduction caused by temperature rise must be estimated, that is to say, the axial clearance should be adjusted a little larger.
For the bearing with low speed and bearing vibration, it should be installed without clearance or with preload. Its purpose is to make the roller and raceway of tapered roller bearing have a good contact, the load is evenly distributed, and prevent the roller and raceway from being damaged by vibration and impact. After adjustment, check the axial clearance with a dial indicator.
Installation of four row tapered roller bearings (installation of roller bearings)
1、 The inner ring of the four row tapered roller bearing is generally fitted with the roller neck with clearance. During the installation, the bearing is first installed into the bearing box, and then the bearing box is installed into the journal.
2、 The outer ring of the four row tapered roller bearing and the bearing housing hole also adopt dynamic fit. First, install the outer ring a into the bearing housing. The word {hottag} is printed on the outer ring, inner ring and inner and outer spacer rings when they are delivered from the factory. When they are installed, they must be installed into the bearing box in the order of the character symbols. It can not be interchanged to prevent the change of bearing clearance.
3、 After all the parts are installed in the bearing box, the inner ring and the inner ring, the outer ring and the outer ring are axially close.
4、 Measure the gap width between the outer ring end face and the bearing housing cover plate to determine the thickness of the corresponding sealing gasket.
Multi seal bearings are marked with XRS code.
parameter
Size range
The basic dimensions of ZWZ tapered roller bearing are listed in the dimension data sheet,
Single row tapered roller bearings:
Inner diameter range: 20 mm ~ 1270 mm
Outer diameter range: 40mm ~ 1465mm
Width range: 15mm ~ 240mm
Double row tapered roller bearing:
Inner diameter range: 38mm ~ 1560mm
Outer diameter range: 70mm ~ 1800mm
Width range: 50mm ~ 460mm
Four row tapered roller bearings:
Inner diameter range: 130mm ~ 1600mm
Outer diameter range: 200 mm ~ 2000 mm
Width range: 150 mm ~ 1150 mm
tolerance
ZWZ Metric tapered roller bearing has common tolerance, and also provides p6x, P6, P5, P4, P2 tolerance products, all in line with gb307.1.
ZWZ Inch Tapered roller bearing has common tolerance, and can also provide Cl2, CL3, CL0, cl00 tolerance products according to the needs.
Radial clearance
ZWZ single row tapered roller bearing has clearance only after installation, and can be determined only after another bearing located in the opposite direction is adjusted.
Cage
Tapered roller bearings generally use steel plate stamping, basket cage, but when the size is large, also use car made solid pillar cage.
1. When the outer diameter of the bearing D ≤ 650mm, the steel plate is used to punch the cage, and the rear code of the cage is not marked
2. When the outer diameter of bearing d > 650mm, the steel solid support cage shall be used, and the cage rear code shall not be marked
Permissible error
equivalent dynamic load
P = fr, kn] when fa / FR ≤ e
P = 0.4fr + yfa [kn] when fa / FR > e
When single row tapered roller bearings are used in pairs (the basic dimensions may be different), the additional axial force caused by radial load must be taken into account when calculating the equivalent dynamic load of bearings. The additional axial force s of single row tapered roller bearing can be approximately calculated as follows: S = FR / 2Y
Equivalent static load
Single row tapered roller bearing
P0=0.5Fr +Y0Fa KN]
If P 0 < fr, then p 0 = fr
Double row and four row tapered roller bearings
P = 0fr + y1fa [kn] when fa / FR ≤ e
P = 0.67fr + y2fa [kn] when fa / FR > e
Suffix definition
A: Change of internal structure
B: Increased contact angle
10: International standards are adopted for overall dimensions
CD: double outer ring with oil hole or oil groove.
TD: double inner ring with taper hole.
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