Angular contact ball bearings

Angular contact ball bearing have high limit rotational speed, they can carry radial load and axial

load simultaneously, they cal also withstand purely radial load. The axial load carrying capacity depends

on the magnitude of contact angle and increases with increasing contact angle.

Structures

1. Separable angular contact ball bearings

The inner ring and outer ring of this type of bearings cannot be separated and comprises

following structures:

Contact angle *=15°, counter bore on outer ring, 7000C type

Contact angle *=25°, counter bore on outer ring, 7000AC type

Contact angle *=40°, counter bore on outer ring, 7000B type

2. Four-point contact ball bearings

This type of bearings is separable bearings. Whereof, QJ000 type has two-piece inner ring and QJF000 type has two-piece outer ring. Their contact angles are same as 35°. When received no load or pure radial load, the steel balls of the ball bearing contact with the four points of the rings. Besides the steel balls perform a two-point contact with the ring when it is received a pure axial load. In addition, besides the axial load from both directions, this kind of bearing can take torque-load as well.

3. Double row angular contact ball bearings

This kind of bearings can accommodate radial loads as well as axial loads acting in both directions; they can also take torque-load. They can restrain the axial displacement from both directions of the shaft or housing; the contact angle is 30° (or 40°).

Cage material

Angular contact ball bearings generally adopt pressed steel cages or copper solid cages. Double-row angular contact ball bearings generally adopt copper solid cages.

Permissible tilt angle

There is only a little inclination between the inner ring and outer ring of angular contact bearings, the permissible tilt angle varies according to the internal clearance when the bearings are operating, the bearing dimensions, internal design and the force and torque-load received by the bearings. The value of the maximum permissible tilt angle should be able to ensure that no much extra stress to be generated inside the bearings. The tilt angle existing between the inner ring and outer ring will influence the bearing service life. Meanwhile, the running accuracy is decreased down and noise increased.

Dynamic equivalent radial load

1)    Single bearing or tandem arrangement of single-row angular contact ball bearings with a contact angle of 15°.

2)    Single bearing or in tandem arrangement*7000C*7000C/DT*

Pr=Fr When Fa/Fr * e

Pr=0.44Fr+YFa When Fa/Fr *e

Back-to-back and face-to-face arrangements*7000C/DB*7000C/DF*

Pr=Fr +Y1Fa When Fa/Fr *e

Pr=0.72Fr+Y2Fa When Fa/Fr *e

                 See Table 2-2 for the values of e, Y, Yl and Y2. 2)

Single-row angular contact ball bearings with a contact angle of 25°. Single bearing or tandem arrangement*7000AC*7000AC/DT* Pr=Fr When Fa/Fr*0.68 Pr=0.41Fr+0.87Fa When Fa/Fr*0.68 Back-to-back and face-to-face arrangements*7000AC/DB*7000AC/DF* Pr=Fr+0.92Fa When Fa/Fr*0.68 Pr=0.67Fr+1.41Fa When Fa/Fr*0.68

3) Single-row angular contact ball bearings with a contact angle of 40°. Single bearing or tandem arrangement*7000B*7000B/DT* Pr=Fr When Fa/Fr*1.14 Pr=0.35Fr+0.57Fa When Fa/Fr*1.14 Back-to-back and face-to-face arrangements*7000B/DB*7000B/DF* Pr=Fr+0.55Fa When Fa/Fr*1.14 Pr=0.57Fr+0.93Fa When Fa/Fr*1.14

4) Four point contact ball bearings with a contact angle of 35° Pr=Fr+0.66Fa When Fa/Fr*0.95 Pr=0.6Fr+1.07Fa When Fa/Fr*0.95

5) Double-row angular contact ball bearings with a contact angle of 45°. Pr=Fr+0.47Fa When Fa/Fr*1.34 Pr=0.54Fr+0.81Fa When Fa/Fr*1.34 In the formula: Pr Dynamic equivalent radial load (N) Fr Actual radial load of the bearing (N)

Static equivalent radial load

1) Single bearing or tandem arrangement of single-row angular contact ball bearings with a contact angle of 15°.*7000C*7000C/DT* Por=0.5Fr+0.46Fa

Por=Fr When Por*Fr Back-to-back and face-to-face arrangements*7000C/DB*7000C/DF* Por=Fr+0.92Fa

2) Single-row angular contact ball bearings with a contact angle of 25°. Single bearing or tandem arrangement*7000AC*7000AC/DT* Por=0.5Fr+0.38Fa Por=Fr When Por*Fr Back-to-back and face-to-face arrangements*7000AC/DB*7000AC/DF* Por=Fr+0.76Fa

3) Single-row angular contact ball bearings with a contact angle of 40°.

Single bearing or tandem arrangement*7000B*7000B/DT* Por=0.5Fr+0.26Fa Por=Fr When Por*Fr

Back-to-back and face-to-face arrangements*7000B/DB*7000B/DF* Por=Fr+0.52Fa

4) Four point contact ball bearings with a contact angle of 35° Por=Fr+0.58Fa

5) Double-row angular contact ball bearings with a contact angle of 45°.

    Por=Fr+0.44Fa

In the formula:    

   Por    Dynamic equivalent radial load (N)

   Fr Actual radial load of the bearing  (N)

A damaging sliding will be generated between the balls and the raceway by inertia force when preventing the bearings from high speed rotating, so the bearing must carry certain load. The minimum load can be estimated with the equation below:

1. Single-row angular contact ball bearings

1) The minimum axial preload of a single bearing or a tandem arrangement Famin=Ka(Cor/1000)(ndm/100000) 2 2)The minimum axial preload of back-back or face-to-face arrangement Frmin=Kr(vn/1000) 2/3(dm/100) 2

In the formula: Famin The minimum axial preload (N) Frmin The minimum radial preload (N)

Cor Basic static load rating (N) n Bearing rotation speed                           (r/min) dm Bearing mean diameter dm = (d+D)/2 (mm)

V Lubricating oil viscosity under operating temperature *mm /s2*

Ka Minimum axial load factor Ka=1.4 72series Ka=1.6 73series

Kr Minimum radial load factor Kr=95 72series Kr=100 73series

2. Double-row angular contact ball bearings

Minimum radial preload

Frmin=Kr(Vn/1000)2/3(dm/100) 2

In the equation:   Frmin  Minimum radial preload (N)

   n  Bearing rotation speed (r/min)

    dm    Bearing mean diameter m=(d+D)/2    (mm)

   V  Lubricating oil viscosity under operating temperature 2(mm /s)

   Kr Minimum radial load factor

        Kr=80 32series   

        Kr=60 32Aseries  

        Kr=95 33series   

3. Four point angular contact ball bearings

Minimum axial preload Famin=Ka(Cor/1000)(ndm/100000) 2

In the equation:   Famin Minimum axial preload (N) Cor Basic static axial load rating (N) n Bearing rotation speed (r/min) dm Bearing mean diameter m=(d+D)/2 (mm) Ka Minimum axial load factor

Ka=1.0 QJ2series Ka=1.1 QJ3series

When the actual load acted on the bearing is less than the minimum load computed, a spring and other measures must be used to preload the bearing.

Operating temperature

-20*+120* When the operating temperature exceeds +120*, please contact with Technical Department.

Safety coefficient

The allowable equivalent static load of a bearing depends on the basic static load rating of the bearing. While permanent deformation quantity said above (local depressed quantity) decides bearing performance and service conditions.

So, safety coefficient is made out for analyzing the safety degree of the basic static load rating. So=Cor/Pormax

In the equation: Pormax The maximum static equivalent load allowed to be acted on the bearing (N) Cor Basic static load rating (N)

So See Annexed Table 1 for the operational safety coefficient

Basic rating life

The simplest method to calculate the life of cylindrical roller bearings is to use ISO Basic rating life formula: L10=(Cr/Pr)3

In the formula:    L10    Basic rating life  (10 revolutions)

    Cr    Basic dynamic radial load rating   (N)

    Pr    Dynamic equivalent radial load (N)

1. The largest single round angle radius of the shaft and bore, rasmax is seen in Annexed Table 3

2. The minimum height of abutment hmin is seen in Annexed Table 3.

3. Calculation of mounting dimensions.

The height of shaft or the abutment of the bore is larger than the largest permissible size of bearing chamfer, and the shasft or bore abutment contacts the plain part of bearing end face; the corner radium of the shaft and the bore, rasmin, is smaller than the smallest permissible size of bearing chamfer, so not to affect mounting. Generally the values of abutments and corner radium in Appendix 3 are adopted.    In order to reduce stress concentration and increase shaft intensity, when it is required that the corner radium of the abutment size of the shaft and bore is larger than the size of bearing chamfer which results in insufficient contact area, then a spacer can be put between the abutment of the shaft or bore with the bearing. The mounting dimensions of rolling bearings are the connecting sizes in connection with the internal design of the bearings. For angular contact ball beatings, the mounting dimensions are mainly depend on the actual end face width of inner ring and outer rings. The minimum value of abutment hmin is given in the standard; the main unit designers can follow the formula below to calculate mounting dimensions:

dbmin=d+2hmin Dbmax=D-2hmin In the formula: dbmin Minimum diameter of shaft abutment (mm) Dbmax Maximum diameter of seat bore abutment (mm)

In order to get the optimum design for the bearing parts, the main designer should contact with Technical Department.

Customer services

According to customers needs to design all kinds of standard and nonstandard angular contact ball bearings, please contact with Technical Department for related information.

Table l Operational safety coefficient     So

In the formula:

1. The largest single round angle radius of the shaft and bore, rasmax is seen in Annexed Table 3.

3. Calculation of mounting dimensions.

The height of shaft or the abutment of the bore is larger than the largest permissible size of bearing chamfer, and the shasft or bore abutment contacts the plain part of bearing end face; the corner radium of the shaft and the bore, rasmin, is smaller than the smallest permissible size of bearing chamfer, so not to affect mounting. Generally the values of abutments and corner radium in Appendix 3 are adopted.    In order to reduce stress concentration and increase shaft intensity, when it is required that the corner radium of the abutment size of the shaft and bore is larger than the size of bearing chamfer which results in insufficient contact area, then a spacer can be put between the abutment of the shaft or bore with the bearing. The mounting dimensions of rolling bearings are the connecting sizes in connection with the internal design of the bearings. For angular contact ball beatings, the mounting dimensions are mainly depend on the actual end face width of inner ring and outer rings. The minimum value of abutment hmin is given in the standard; the main unit designers can follow the formula below to calculate mounting dimensions:

dbmin=d+2hmin Dbmax=D-2hmin In the formula: dbmin Minimum diameter of shaft abutment (mm) Dbmax Maximum diameter of seat bore abutment (mm)

In order to get the optimum design for the bearing parts, the main designer should contact with Technical Department.

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Angular contact ball bearings

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