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Tapered roller bearings

January 16, 2020

Tapered roller bearings are separate bearings. Both the inner and outer rings of the bearing have tapered raceways. This type of bearing is divided into single, double and four-row tapered roller bearings according to the number of rollers installed. Single-row tapered roller bearings can support radial loads and axial loads in one direction. When the bearing is subjected to a radial load, an axial component will be generated, so when another bearing that can withstand the axial force in the opposite direction is needed to balance it.

Tapered roller bearings refer to radial thrust rolling bearings in which the rolling elements are tapered rollers. There are two kinds of small cone angle and large cone angle. The small cone angle mainly bears the combined radial and axial loads mainly with radial loads. It is often used in pairs and installed in reverse. The inner and outer races can be installed separately. The radial and axial clearance can be adjusted during installation and use; The large cone angle mainly bears the axial and radial combined loads, which are mainly axial loads. Generally, it is not used to bear pure axial loads alone. When configured in pairs (installed with the same name opposite), it can bear pure radial loads.
Definition edit
The single-row tapered roller bearing's ability to withstand axial load depends on the contact angle, that is, the outer ring raceway angle. The larger the angle, the greater the axial load capacity. The most used tapered roller bearings are single-row tapered roller bearings. In the front wheel hub of the car, a small double-row tapered roller bearing is used. Four-row tapered roller bearings are used in heavy machines such as large cold and hot rolling mills.
Structural Features
The type code of tapered roller bearings is 30,000, and tapered roller bearings are separate bearings. In general, especially in the dimensions covered by GB / T307.1-94 "Tolerances for rolling bearings, radial bearings", the outer ring and inner components of the tapered roller bearing are 100% interchangeable.
The angle of the outer ring and the diameter of the outer raceway have been standardized as the same as the outer dimensions. No changes are allowed during design and manufacture. As a result, the outer ring and inner components of tapered roller bearings can be universally interchanged worldwide.
Tapered roller bearings are mainly used to support the combined radial and axial loads, mainly radial loads. Compared with angular contact ball bearings, the bearing capacity is large and the limiting speed is low. Tapered roller bearings can withstand axial loads in one direction and can limit axial displacement of the shaft or housing in one direction. [2]
Category editor
The single-row tapered roller bearing has an outer ring, an inner ring and a set of tapered rollers, which is an inner ring component formed by a basket-shaped cage. The outer ring can be separated from the inner ring component. According to the ISO standard for external dimensions of tapered roller bearings, the outer ring or inner ring component of any standard tapered roller bearing should be able to achieve internationality with the outer ring or inner ring component of the same model. exchange. That is to say, in addition to the outer dimensions and tolerances of the same type of outer ring must comply with ISO492 (GB307) regulations, the cone angle and cone diameter of the inner ring components must also meet the relevant regulations for interchange.
Generally, the tapered angle of the outer ring raceway of a single-row tapered roller bearing is between 10 ° and 19 °, which can simultaneously bear the combined action of axial load and radial load. The larger the cone angle, the greater the ability to withstand axial loads. Bearings with a large tapered angle, with a post code plus B, with a tapered angle between 25 ° and 29 °, can bear large axial loads. In addition, single-row tapered roller bearings can adjust the amount of clearance during installation.
The outer ring (or inner ring) of a double-row tapered roller bearing is a whole. The two small inner end faces of the inner ring (or outer ring) are close to each other and there is a spacer in the middle. The clearance is adjusted by the thickness of the spacer. The thickness of the spacer can also be used to adjust the pre-interference of the double-row tapered roller bearing.
Four-row tapered roller bearings, the performance of this bearing is basically the same as double-row tapered roller bearings, but the radial load is greater than double-row tapered roller bearings, the limit speed is slightly lower, mainly used in heavy machinery.
Multi-sealed double and four-row tapered roller bearings, ZWZ provides long-life, multi-sealed double and four-row tapered roller bearings. The bearing is individually and completely new designed, and the traditional design method of fully sealed bearings is changed. A new type of sealing structure combining sealing and dustproof is adopted to improve the sealing effect and sealing performance. Compared with open structure bearings, multi-sealed double-row and four-row tapered roller bearings have a 20% to 40% longer life and a 80% reduction in lubricant consumption.
Purpose edit
Tapered roller bearings mainly bear radial and axial combined loads. Bearing capacity depends on the raceway angle of the outer ring, the larger the angle the bearing
The greater the carrying capacity. This type of bearing is a separate bearing, which is divided into single row, double row and four row tapered roller bearings according to the number of rows of rolling elements in the bearing. The clearance of the single-row tapered roller bearing needs to be adjusted by the user during installation; the clearance of the double-row and four-row tapered roller bearings has been given according to the user's requirements when the product leaves the factory, and does not require the user to adjust.
Tapered roller bearings have tapered inner and outer ring raceways with tapered rollers arranged between them. The projection lines of all conical surfaces converge at the same point on the bearing axis. This design makes tapered roller bearings particularly suitable for bearing combined (radial and axial) loads. The axial load capacity of a bearing is mostly determined by the contact angle α; the larger the angle α, the higher the axial load capacity. The angle is expressed by the calculation coefficient e; the larger the value of e, the larger the contact angle, and the greater the applicability of the bearing to the axial load.
Tapered roller bearings are usually separated, that is, a tapered inner ring assembly composed of an inner ring with a roller and a cage assembly can be installed separately from the tapered outer ring (outer ring).
Tapered roller bearings are widely used in automobiles, rolling mills, mining, metallurgy, plastic machinery and other industries.
Installation edit
The following information is provided by Kuaiyiyou Automation Selection.
Adjusting the axial clearance For the installation of tapered roller bearings, the axial clearance can be adjusted by adjusting nuts on the journal, adjusting washers and the threads in the bearing housing holes, or by pre-tensioning the spring. The size of the axial clearance is related to the arrangement of the bearing, 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, when adjusting the clearance, the effect of temperature rise on the axial clearance must be considered, and the amount of clearance reduction caused by temperature rise must be taken into account, that is, axial clearance Make it bigger.
For bearings with low speed and vibration, it should be installed without clearance or installed with preload. The purpose is to make the rollers and raceways of tapered roller bearings have good contact, and the load is evenly distributed to prevent the rollers and raceways from being damaged by vibration and shock. After adjustment, the amount of axial clearance is checked with a dial indicator.
Installation of four-row tapered roller bearings (installing roller bearings):
The fit between the inner ring of the four-row tapered roller bearing and the roll neck is generally with clearance. When installing, first place the bearing in the bearing housing, and then install the bearing housing into the journal.
The outer ring of the two or four-row tapered roller bearing and the bearing box hole also adopt a dynamic fit, and the outer ring A is first installed into the bearing box. The {HotTag} symbol is printed on the outer ring, the inner ring and the inner and outer spacers when leaving the factory. During installation, the bearing box must be installed in the order of the character symbols. Not interchangeable to prevent changes in bearing clearance.
3. After all the parts are installed in the bearing box, the inner ring and the inner spacer ring, the outer ring and the outer spacer ring are axially tight.
4. Measure the width of the gap between the end face of the outer ring and the cover of the bearing box to determine the thickness of the corresponding gasket.
Multi-seal bearings are marked with the rear designation XRS. [3]
Parameter editing
Size range
The basic dimensions of ZWZ tapered roller bearings are listed in the dimension data table.
Single-row tapered roller bearings:
Inner diameter size range: 20mm ~ 1270mm
Outer diameter range: 40mm ~ 1465mm
Width size range: 15mm ~ 240mm
Double-row tapered roller bearings:
Inner diameter size range: 38mm ~ 1560mm
Outer diameter range: 70mm ~ 1800mm
Width size range: 50mm ~ 460mm
Four-row tapered roller bearings:
Inner diameter size range: 130mm ~ 1600mm
Outer diameter range: 200mm ~ 2000mm
Width size range: 150mm ~ 1150mm
tolerance
ZWZ metric tapered roller bearings have ordinary tolerances. P6X, P6, P5, P4, and P2 tolerance products are also available, all in accordance with GB307.1.
ZWZ inch tapered roller bearings have common tolerances, and CL2, CL3, CL0, CL00 tolerance products are also available on request.
Radial clearance
ZWZ single-row tapered roller bearings have clearance only after installation, and can only be determined after adjusting with another bearing positioned in the opposite direction.
Cage
Tapered roller bearings generally use steel stamping and basket-shaped cages, but when the size is larger, they also use car solid pillar cages.
1. When the bearing outer diameter D≤650mm, a steel stamped cage is used, and the code behind the cage is not marked.
2. When the bearing outer diameter D> 650mm, the steel solid pillar cage is used, and the code behind the cage is not marked
Allowable 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 external dimensions can be different), when calculating the equivalent dynamic load of the bearing, the additional axial force caused by the radial load must be taken into account. The additional axial force S of a single-row tapered roller bearing can be approximated by the following formula: S = Fr / 2Y
Equivalent static load
Single row tapered roller bearing
P0 = 0.5Fr + Y0Fa KN]
If P0 Double 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: Internal structure change
B: increased contact angle
X: External dimensions adopt international standards
CD: Double outer ring with oil hole or oil groove.
TD: Double inner ring with tapered hole.