Siemens SINAMICS S 1PH7, Configuration Manual

Page: 73 / 244

Mechanical properties of the motors
3.4 Radial and axial forces
1PH7 induction motors (Machine tools)
Configuration Manual, (APH7W), 04/2009, 6SN1197-0AD72-0BP0
73
3.4.3 Axial force
The axial force acting on the bearings comprises an external axial force (e.g. gearbox with
helical gearing, machining forces through the tool), a bearing pre-load force and possibly the
force due to the weight of the rotor when the motor is vertically mounted. This results in a
maximum axial force that is a function of the direction.
When using, for example, helical toothed wheels as drive element, in addition to the radial
force, there is also an axial force on the motor bearings. For axial forces in the direction of
the motor, the spring-loading of the bearings can be overcome, which under circumstances,
can result in an axial shift of the rotor. This must be prevented as otherwise it could reduce
the bearing and encoder lifetime.
Calculating the permissible axial force F
AZ
The permissible axial force F
AZ
in operation depends on the motor mounting position.
Table 3- 12 Calculating the permissible axial force
Horizontal arrangement
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Shaft end facing downwards
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Shaft end facing upwards
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F
AZ
Permissible axial force in operation
F
A
Permissible axial force as a function of the average speed
F
C
Pre-loading force
F
L
Force due to weight of rotor