Siemens SINUMERIK 840C - Manual (Page 714)

10 Axis and Spindle Installation 12.93
10.4.1 Drive optimization
10.4.1.3 Servo gain factor K
V
NC MD 252*
To achieve only negligible contour deviations with continuous path control, a high K
V
(servo
gain) factor (NC MD 252*) is required.
If the K
V
factor is too high, however, instability, overshoots and possibly excessive machine
loads result.
The maximum permissible K
V
factor depends on:
• the drive configuration
(rise time, acceleration and braking ability).
• the quality of the machine
The K
V
factor is defined as
K
V
=
Speed
Following error
[m/min]
[mm]
m/min
mm
is the unit of the K
V
factor according to VDI standard
If an empirical value for the K
V
factor is known for the machine, set this value and check for
overshooting or instability.
Good speed controller optimization is a precondition for
a correct K
V
factor setting.
K
V
factor adjustment
Reduce the acceleration (NC MD 276*). The overshoot behaviour is decisive for evaluating the
maximum K
V
factor. The acceleration must therefore be set at an accordingly low level to
ensure that the drive remains below its current threshold.
If the drive is intended to have acceleration of 1 m/s 2 , adopt a cautious approach and reduce
to one-half of the value
0.5 m/s 2 ˆ = input 50
10–24 © Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)