certific at e - NOC international

Friction
for symmetrical bearings
foil factor for the bearing diameter
D
25 für — ≤ 1,5
d
External heating/external cooling
If the roller bearing in operation is affected by temperatures which are not caused by its friction alone, but by its environment,
e. g. inside a transmission or inside equipment using process heat, you should estimate the amount of
heat to be transferred from the roller bearing. Determine the power in kW.
These technical conditions are in part included in the best of practice operating temperatures specified, but if you
need to calculate the operating viscosity, you should consider the bearing specifics of your application.
Technologically caused external heating
Bearing with technologically
caused external heating Operating temperature [°C]
Electric drive motors 80 ... 90
Drying chamber on paper machines 120 ...130
Hot gas ventilators 120
Water pumps on car 20
Engine crankshafts 120
Calender rollers for plastic moulds 180
Wheel bearings of rotary kilns 200 ... 300
The same applies to the influence of the bearing cooling system, e. g. in a rolling mill, where the lubricating film has
not only to remove the friction heat calculated, but also the process heat of the environment.
The following applies:
N R = Q [W]
N R = M R · n · 1,047 · 10 -4
[W]
N R Total friction heat [W]
M R Total moment of friction [Nmm]
n Operating speed [rpm]
Q = Q L + Q oil + Q A - Q F [W]
Q Heat removal capacity (total) [W]
Q L Heat removal through convection [W]
Q oil Cooling through lubrication oil [W]
QA External cooling [W]
A
D
40 für — > 1,5
d
for asymmetrical bearings
f oil
factor for the bearing diameter
D
200 für — ≤ 1,5
d
D
250 für — > 1,5
d
Q F External heat (proportionate process heat) [W]
Use of the equations should nevertheless not ignore friction torques, friction losses, and heat removal.
KRW 123