plaquette MACHLINE - Ntn-snr.com

Rigidity
and axial deflection
Rigidity as a function of preload
Example: a 7012 bearing assembled in DB
Comparison of rigidity by series
80
80
70
Radial 7012CV
70
Rigidity (daN/µm)
60
50
40
30
Radial 7012HV
Axial 7012HV
Axial 7012CV
Rigidity (daN/µm)
60
50
40
30
CH71912HV
71912HV
CH7012HV
7012HV
CH7212HG1
7212HG1
20
20
10
10
0
0 200 400 600 800 1000 1200 1400 1600
Preload (daN)
The rigidity is given by the preload. As preload
increases, rigidity also increases in a non-linear
manner.
0
0 200 400 600 800 1000 1200 1400 1600
Preload (daN)
Axial deflection of an angular contact ball bearing
When a bearing is subject to an axial load Fa in daN,
one of the rings undergoes axial displacement with
respect to the other, with a value δa: δa = K( Fa) 2/3
K is the axial deflection constant for each bearing and
its value is given in the preload table (see page 44).
25
3
2
2δ
Axial displacement (µm)
20
15
10
5
Displacement
of bearing
3 inner ring
Displacement
of bearings
1 and 2 inner rings
Preload application:
For instance, let us take an assembly, Q16,
with preload Pr on its bearings. There is a
gap of 2δ between the inner rings of bearings
2 and 3 prior to preloading.
2δ = 2K(Pr) 2/3
If the inner rings are abutted such as to
close the gap 2δ, the displacement is
shown in the diagram opposite. The equilibrium
preload for the assembly equals
PE when clearance 2δ is eliminated.
1
0 500 1000 1500 2000 2500 3000
PE
Preload (N)
15