Double Row Angular Contact Ball Bearings

Detail Introduction :

Double row angular contact ball bearings is a kind of radial and axial combined load and moment load that can bear a large radial load mainly used to limit the shaft and shell two-way axial displacement in the parts. Now it has spread all over the world, with business in 130 countries around the world, producing more than 500 million bearings per year, with sales network all over the world.

Double row angular contact ball bearing as high quality double row angular contact ball bearing, compared with single row bearing double row angular contact ball bearing has better rigidity, can withstand the tilting moment, is the current machinery and equipment preferred bearing.

In all skf bearings, double row angular contact ball bearings in the design with two single row angular contact ball bearings correspond, and occupy less axial space, can withstand radial load as well as the role of the axial load in two directions. The auxiliary equipment is fully utilized for maximum performance.

Because of this, Double Row Angular Contact Ball Bearing has a wide range of applications.

Mainly used to limit the axial displacement of the shaft and shell in both directions in the components, the bearing is non-separable, so it is particularly suitable for applications with high rigidity requirements, widely used in the front wheel hub of small cars, as well as oil pumps, Roots blowers, air compressors, all kinds of transmissions, fuel injection pumps and printing machinery.

In recent years, Double row angular contact ball bearings have been a world-renowned bearings, with excellent quality, excellent design, simple structure, reliable quality, wear resistance, long service life, low failure rate, no special maintenance and other advantages to harvest a lot of consumer recognition, and has become the industry's development of the wind vane.

In addition, more than 80% of the steel used in the production of double row angular contact ball bearings is provided by skf steel mills, which can fully guarantee the quality of raw materials, and all important equipment are designed and combined by skf, only to enable all skf factories around the world to achieve the most advanced production level. The Double row angular contact ball

Double row angular contact ball bearings are specially machined so that when the bearings are mounted close to each other, any combination can achieve the established internal clearance or preload and even load distribution without the use of shims or similar devices, helping you get the job done more easily.

About Double row angular contact ball bearing Main features.

Double row angular contact ball bearing has limited tiltability between inner and outer ring, the allowable tilt angle depends on the internal clearance of the bearing, bearing size, internal design and the force and moment acting on the bearing, and the maximum allowable tilt angle should ensure that no excessive additional stress will be generated inside the bearing.

If there is a tilting angle between the inner and outer ring of the bearing, it will affect the life of the bearing, and at the same time cause the bearing running accuracy to decrease and the running noise to increase. Double row angular contact ball bearings generally use nylon cage or brass solid cage. Double angular contact ball bearing installation should be noted, although the bearing can bear two-way axial load, but if there is a ball loading gap on one side, it should be careful not to let the main axial load through the notched side of the groove edge. In the use of bearings should pay attention to make the side of the raceway without the ball loading notch to bear the main load.

In order to meet the different needs of customers to install double row angular contact ball bearing, Double row angular contact ball bearing has three installation methods: back-to-back, face-to-face, tandem arrangement.
When back-to-back installation, the contact angle line of the bearing spreads along the rotary axis direction; when face-to-face installation, the contact angle line of the bearing converges towards the rotary axis direction, the ground bearing angle is less rigid, because the inner ring of the bearing extends out of the outer ring, when the outer ring of the two bearings are pressed together, the original clearance of the outer ring is eliminated, which can increase the preload of the bearing; when tandem arrangement is installed, the contact angle line of the bearing is in the same direction and parallel. It can make the two bearings share the working load in the same direction.

In addition, the most basic advantage of double row angular contact ball bearing is that it can play a very good support role, can bear radial load, and can also be used to fix the shaft, if there is no bearing on the motor, then it will not be able to work, SKF bearings are the basic existence to ensure the operation of the motor.

Skf bearings come from all over the world, but they all have a very high quality standard, now skf in the global bearing industry to maintain a leading position, over the years always persist in technological research and development, improve the quality of products and services, has developed into a real supply solution-oriented bearing companies, for the majority of manufacturers to create a very large value.

Detailed description of Double row angular contact ball bearings are available through the following content.

1. Double row angular contact ball bearing Designs and variants
The SKF standard assortment of double row angular contact ball bearings (fig. 1) includes:

fig. 1

1.bearings in the 32 A and 33 A series
2.bearings in the 33 D series
3.capped bearings
4.open bearings (that are also available capped) that may have recesses in the ring side faces
Bearings in the 52 and 53 series are no longer available and have been replaced with 32 A and 33 A series bearings, which are dimensionally interchangeable. Only size 3200 A is different, and has a width of 14 mm instead of 14,3 mm.

Double row angular contact ball bearing Basic design bearing concepts：have different tolerances and performance capabilities compared with SKF Explorer bearings

Double row angular contact ball bearings Basic design bearing concept：have different tolerances and performance capabilities compared with SKF Explorer bearings

Double row angular contact ball bearing is a bearing with two-piece inner ring：

1.incorporate a larger number of balls, and have a larger contact angle, giving the bearing its high load carrying capacity, especially in the axial direction
2.are separable in the 33 D series (fig. 2), i.e. the outer ring with ball and cage assemblies can be mounted independently of the inner ring halves

fig. 2

are non-separable in the 33 DNRCBM series (fig. 3)

fig. 3

have a snap ring groove with a snap ring in the outer ring, enabling simple and space-saving axial location in the housing
have been designed specifically for centrifugal pumps, but can also be used in other applications

The main reason why skf is recognized and so popular in the global machinery industry is because of their wide range of bearings. Among them SKF offers the most common basic designs and SKF Explorer bearings with contact seals or shields on both sides.

Double row angular contact ball bearing Bearings with caps：
Shields
1.are identified by designation suffix 2Z (fig. 4)
2.are made of sheet steel
3.extend into a recess on the inner ring

Contact seals
1.are identified by designation suffix 2RS1 (fig. 5)
2.are made of NBR
3.are reinforced with a sheet steel insert
4.are fitted in a recess on the outer ring and make good, positive contact with the recess
5.have a lip that exerts light pressure against the recess on the inner ring to provide an effective seal

When capped bearings must operate under certain conditions, such as very high speeds or high temperatures, grease may appear between the inner ring and capping device. For bearing arrangements where this would be detrimental, appropriate actions should be taken.

Greases for capped bearings

Bearings capped on both sides are lubricated for the life of the bearing and are virtually maintenance-free. They are filled with one of the following greases (table 1):

table 1

1.as standard → GJN
2.in Europe → MT33 (commonly used and widely available)
3.low-friction grease → GE2
4.other greases (table 1) can be supplied on request
The standard grease is not identified in the bearing designation (no designation suffix). Other greases are indicated by the corresponding grease suffix.

Grease life for capped bearings

1.is presented as L10, i.e. the time period at the end of which 90% of the bearings are still reliably lubricated (diagram 1)
2.depends on: the operating temperature、the ndm value、grease performance factor (GPF) (table 1)

diagram 1

The indicated grease life is valid under this combination of operating conditions:
1.horizontal shaft
2.inner ring rotation
3.light load (P ≤ 0,05 C)
4.operating temperature within the green temperature zone of the grease (table 1)
5.stationary machine
6.low vibration levels

Where the operating conditions differ as described below, the grease life obtained from the diagrams should be adjusted:
1.vertical shafts → 50% of the obtained value
2.heavier loads (P > 0,05 C) → apply reduction factor (table 2)

table 2

Cages：
Double row angular contact ball bearings are as standard equipped with either a cage made of PA66 or of stamped steel, among others, as shown in table 3.

When used at high temperatures, some lubricants can have a detrimental effect on polyamide cages.

Each of Skf's bearings has been reasonably designed and researched to ensure reliable quality, wear resistance, long service life, low failure rate, no special maintenance, etc. In addition to this, attention should also be paid to temperature limits during the work with Double row angular contact ball bearings.

2.Temperature limits

The permissible operating temperature for angular contact ball bearings can be limited by:
1.the dimensional stability of the bearing rings and balls
2.the cage
3.the seals
4.the lubricant

Where temperatures outside the permissible range are expected, contact SKF.

Bearing rings and balls
The bearings are heat stabilized up to at least 150 °C (300 °F).

Cages
Steel or brass cages can be used at the same operating temperatures as the bearing rings and balls. For temperature limits of cages made of other polymer materials, refer to Polymer cages.

Seals
The permissible operating temperature for NBR seals is –40 to +100 °C (–40 to +210 °F). Temperatures up to 120 °C (250 °F) can be tolerated for brief periods.
Typically, temperature peaks are at the seal lip.

Lubricants
Temperature limits for greases used in sealed SKF angular contact ball bearings are provided in table 1. For temperature limits of other SKF greases, refer to Selecting a suitable SKF grease.
When using lubricants not supplied by SKF, temperature limits should be evaluated according to the SKF traffic light concept.

diagram 1

3.Permissible speed

The speed ratings in the product table indicate:

1.the reference speed, which enables a quick assessment of the speed capabilities from a thermal frame of reference
2.the limiting speed, which is a mechanical limit that should not be exceeded unless the bearing design and the application are adapted for higher speeds

4.Bearing data

Bearings	Aspects					Snap ring
						Name
Name	C	乙	F	D 3	d 4
–	毫米					–
Chapter 3308	3,28	2,7	2,46	86,8	96,5	SP 90
Chapter 3309	3,28	2,7	2,46	96,8	106,5	SP 100
Chapter 3310	3,28	2,7	2,46	106,8	116,6	SP 110
Chapter 3311	4,06	3,1	2,82	115,2	129,7	SP 120
Chapter 3313	4,9	3,1	2,82	135,2	149,7	SP 140

A complete guide to double row angular contact ball bearings.

Skf bearings can be said to be the basis for the development of the machinery industry, and Skf bearings are very versatile, in fact, different types of bearings are used for different purposes, but in general is to play a supporting role.
The following are some frequently asked questions and answers for Double row angular contact ball bearing.

1.Are double row angular contact bearings preloaded?

Double row angular contact bearings have appropriate internal clearance in its operating condition, but according to the different uses, in the installation need to pre-apply axial load to the bearing, so that it has a negative internal clearance, this practice is preloaded, mostly applicable to angular contact ball bearings or tapered roller bearings.

Generally speaking, the preload of double row angular contact bearings is mandatory, mainly through positioning preload as well as fixed pressure preload two methods to double row angular contact bearings preload, mainly through static bolts, gland, etc. to double row angular contact bearings in advance to apply a force. The purpose of preload is to improve the axial and radial positioning accuracy, and to reduce the runout of the shaft and improve the rotational accuracy. Improve the rigidity of the bearing and improve the gear meshing accuracy; inhibit the rolling body rotational sliding, rotational sliding and rotational sliding, reduce abrasion; prevent the vibration and resonance caused by bearing noise; ensure the correct position of the rolling body and the relative position of the collar.

The size of the preload force must be determined according to the different purposes of preload, in the range of bearing life, temperature rise, friction torque, etc. without adverse effects. In addition, when determining the preload force, the reduction of the preload force, the accuracy of the shaft and housing, the installation and lubrication conditions should be fully considered.

2.What is double row angular contact ball bearing?

Angular contact ball bearing is the radial thrust ball bearing, its allowable working speed is similar to deep groove ball bearing, but the support rigidity is stronger than deep groove ball bearing, mainly because the angular contact bearing can be loaded with more steel balls, the radial bearing capacity is greater than ordinary ball bearing, but also can withstand a large axial load and pure axial load, angular contact ball bearing is generally used in pairs, suitable for small span rigid double-supported Shaft or precision spindle, can further improve the rigidity of the bearing system.

The double row angular contact bearing is two single row angular contact ball bearing outer ring back to coincide, inner ring, outer ring are one structure, simply put is the two single row of bearings at the same time in a bearing, angular contact refers to the edge of the bearing has an angle, therefore, double row angular contact bearing has two directions of thrust load capacity.

Double-row angular contact bearings are more rigid and can withstand overturning moments, so they are especially suitable for some applications with high rigidity requirements.

3.Are angular contact bearings directional?

Angular contact bearings are designed to carry axial load in one direction only. Angular contact bearing front is the thin side of the outer ring, the opposite side is the thick side of the outer ring, if the bearing has "＜" symbol, then the direction of the sharp angle is the opposite, the opening direction is the front. The difference between the positive and negative mounting of angular contact bearing is the different mounting methods, and the looseness of the positive and negative fit directly affects the size of the bearing clearance, which is related to the running accuracy and service life of the bearing.

1.Positive mounting: also called face-to-face mounting, that is, the wide edge is outside, the narrow edge is inside, the other narrow edge is inside and the wide edge is outside, when installed, the contact angle line of the bearing converges towards the direction of the rotation axis, and its support angle is less rigid. As the inner ring of the bearing extends out of the outer ring, when the outer ring of the two bearings are pressed together, the original clearance of the outer ring is eliminated, which can increase the preload of the bearing.
2. Inward mounting: narrow edge outside, wide edge inside, another wide edge inside narrow edge outside, when mounted, the contact angle line of the bearing spreads along the direction of the rotary axis, which can increase its radial and axial support angle rigidity, providing a relatively rigid bearing configuration, and can withstand overturning moment.

4.How do angular contact ball bearings work?

In simple terms, angular contact ball bearings are the support body for rotating shafts, ensuring support force and minimizing friction.
The ball itself carries the weight of the load, and this weight is also the force that drives the rotation of the bearing, but not all loads exert force on the bearing in the same way, there are two main different loads, namely radial and thrust.

Radial loads make the bearings roll or rotate due to tension, while thrust bearings exert pressure on the bearings in a completely different way, angular contact ball bearings are easily subjected to radial loads and axial loads.

Angular contact ball bearings are usually used in pairs, this is because a single row of angular contact ball bearings can only withstand a direction of axial load, in the radial load will cause additional axial force, and can only limit the axial displacement of the shaft or shell in one direction, if the pair of duplex installation, so that a pair of bearing outer ring opposite, that is, the wide end face wide end face, narrow end face narrow end face, so that can avoid causing additional axial force, and Can be in two directions so that the shaft or shell limit in the axial clearance range.

5.Are angular contact ball bearing self aligning?

Angular contact ball bearing can not be self-aligning, angular contact ball bearing can simultaneously withstand radial load and axial load, can work at a higher speed, the larger the contact angle, the higher the axial load carrying capacity. Because of the angular contact ball bearing inner and outer ring raceway can have relative displacement in the horizontal axis, so it can bear radial load and axial load at the same time.

Spherical ball bearing has cylindrical hole and tapered hole two kinds of structure, keep frame material has steel plate, synthetic resin, etc., its point is the outer ring raceway is spherical, has automatic adjusting heart, so can automatically adjust the shaft or shell deflection or different heart caused by the axis is not correct, tapered hole bearing through the use of fasteners can be easily installed in the shaft steel plate stamping keep frame, the inner wheel and steel ball can be freely tilted to the outer wheel, can work at a higher The inner wheel and the steel ball can be freely tilted to the outer wheel and can work under higher speed.

Angular contact ball bearings and spherical ball bearings are two different bearings, if you need automatic centering function, you need to use spherical ball bearings, as to whether the two can be interchanged, you need to consider the specific speed, load, contact angle and other aspects.

6.What is the contact angle on angular contact ball bearing?

Angular contact ball bearing can simultaneously withstand a direction of axial force and radial force, rolling body force point up and down the two points of the line, and the radial direction has a certain angle, such bearings for angular contact bearings. And the contact angle is defined as an imaginary angle between the rolling contact point, join the straight line element, spherical and a straight line perpendicular to the rotation axis, that is, the rolling body and raceway contact of the imaginary line and the rotation axis of the vertical line of the angle.

Angular contact ball bearing contact angle is usually 15 °, 30 °, 40 °, respectively, with the letter C, A, B, angular contact ball bearing mainly bear larger one-way axial load, the larger the contact angle, the greater the load bearing capacity. The cage material has steel plate, brass or engineering plastic, molding method has stamping or turning, depending on the bearing form or use conditions and selection. Angular contact ball bearings can simultaneously withstand radial load and axial load. Can work at a higher speed. The larger the contact angle, the higher the axial load carrying capacity. High precision and high speed bearings usually take 15 degrees contact angle.

7.Is an angular contact bearing a thrust bearing?

Angular contact bearing and thrust bearing are two different bearings, the main differences between the two are as follows.
1. Precision is different: the precision of angular contact bearing is higher than that of thrust bearing, which can withstand higher speed and is usually used as spindle bearing.
2.Different bearing force: thrust bearing can not bear radial force, but angular contact bearing can bear both radial force and axial force, but the ability of thrust bearing to bear axial force is much larger than angular contact bearing, about 2 times.
3.Different mounting forms: Angular contact bearings mainly have back-to-back mounting, face-to-face mounting and tandem bearing arrangement, while thrust bearings only have back-to-back and face-to-face mounting forms.
4. Different uses: thrust bearings are only suitable for bearing one side of the axial load, low speed machine parts, such as crane hooks, vertical pumps, vertical centrifuges, jacks, etc., while angular contact bearings can withstand radial load, larger one-way axial load, dual pairs can withstand two-way axial load and moment load, so usually used in machine tool spindles, high-frequency motors, small car front wheel, etc..

8.how to use angular contact ball bearing double row?

Double row angular contact ball bearing and single row angular contact ball bearing is basically the same, but can occupy less axial space, can withstand larger radial load-based radial and axial combined load and moment load, to limit the axial displacement of both sides of the shaft, mainly used to limit the shaft and shell two-way axial displacement of the components, and single row angular contact ball bearing compared to double row angular contact ball bearing has better rigidity, can withstand Tilting moment, ideal for high rigidity processing and production, suitable for the front wheel hub of small cars.
In use, double row angular contact ball bearing mounting method is complex, mostly for pair mounting, there are three main mounting methods: back-to-back, face-to-face and tandem arrangement.

Back-to-back: the contact angle line of the bearing spreads along the direction of the rotation axis, which can increase its radial and axial support angle rigidity and the greatest resistance to deformation.
Face to face: As the inner ring of the bearing extends out of the outer ring, when the outer rings of the two bearings are pressed together, the original clearance of the outer ring is eliminated, which can increase the preload of the bearing.
Tandem arrangement: The contact angle lines of the bearings are in the same direction and parallel, which can make the two bearings share the working load in the same direction.

Bearings Model: