SIEMENS
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Siemens NC 62 · 2016
Main spindle motors
Gearbox
Two-speed gearbox for SIMOTICS M-1PH8 asynchronous motors
6
■
Application
Gearboxes increase the drive torque at low motor speeds and
extend the range of constant power that the main spindle motor
can deliver. The full cutting capacity of modern machine tools
can therefore be utilized throughout the entire speed range.
■
Benefits
The performance features of the two-speed gearbox for
SIMOTICS M-1PH8 asynchronous motors are as follows:
7
Drive power up to 100 kW (134 HP)
7
Constant power range at drive shaft up to 1:24
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Suitable for both directions of rotation
7
Motor shaft heights SH 100 to SH 225
7
Types of construction IM B35 and IM V15
(IM V35 available on request)
The advantages listed below are gained by mounting the
gearbox outside the spindle box:
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Easy adaptation to the machine tool
7
Low noise and no temperature fluctuations due to gearing
inside the headstock
7
Separate lubrication systems for the main spindle (grease)
and the change-speed gearbox (oil)
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Gear efficiency > 95 %
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The drive power can also be transferred from the gearbox
output via a gear wheel (on request) or coaxially via a flexible
coupling rather than by a V-belt.
■
Design
The two-speed gearboxes have a planetary design. The power is
distributed among several planet wheels from the central sun
gear. Thanks to this gearing design, the gearboxes are extremely
compact. The gear-changing device, a splined sleeve that moves
axially, is of form-fit design.
Position 1: Gear ratio
i
1
= 4
Position 2: Gear ratio
i
2
= 1
The motor is flanged onto the gearbox by an adapter plate. The
three-phase motor must be suitably prepared for gearbox
mounting.
With shaft height AH 160 and above, motors in frame sizes
IM B35 and IM V15 must be supported at the NDE to eliminate
any mechanical stress.
Any transverse force imported into the gearbox has to be borne
by the gearbox and transmitted to the machine base.
The motors for all 2K gearboxes must be full-key balanced with
a feather key. The 2K 120, 2K 250, 2K 300, 2K 450 gearboxes
are sealed so that the motor flange is also adequately sealed in
the standard version.
Vertical mounting positions IM V15 and IM V35 require circulating
lubrication of the gearboxes.
The standard version of the change-speed gearboxes up to and
including the 2K 300 has a maximum circumferential backlash of
30 angular minutes (measured at the gear output). Several
special versions suitable for milling or machining with cut inter-
ruption can be supplied on request:
•
Reduced backlash with special features: max. 20'
•
Reduced backlash for high performance: max. 15'
1)
Not included in scope of delivery.
■
Design
(continued)
Profile of a planetary gearbox
The power unit (motor and gearbox) is supplied with vibration
severity grade R in accordance with EN 60034-14 (IEC 60034-14).
This is also the case when the motor is ordered with vibration
severity grade S.
The belt pulley
1)
must be a cup wheel type pulley. For mounting
the belt pulley, the output shaft on the gearbox has a flange with
an external centering spigot and tapped holes for easy fitting
and removal of the pulley.
■
Characteristic curves
The use of a change-speed gearbox permits the constant power
range to be greatly increased.
Power-speed graph
Legend:
n
rated
Rated speed
n
rated'
Rated speed with two-stage gearbox
n
max
Max. permissible speed
P
rated
Rated power and constant power of motor
in the speed range from
n
rated
to
n
max
or
n
rated'
to
n
max
M
Torque
n
P
P
= constant
P
= constant
with gearbox
without gearbox
n
rated'
n
rated
M
= constant
M
= constant
Logarithmic scale
G_NC01_EN_00017a
n
max
P
rated
1
1
1
1
2
2
2
2
© Siemens AG 2016