Siemens SINUMERIK 840DiE sl Manual page 338

11 NCK Commissioning with HMI Advanced
11.5 Axes and spindles
Checking the
loop gain
n
set
[V]
"Badly"
selected KV factor
Fig. 11-17 Speed setpoint characteristic
Overshoot in the
control loop
Acceleration
Default values
11-338
If a K factor is already known for a machine type in question, this can be set
V
and checked. For checking, reduce the acceleration of the axis in
S
MD32300: MAX_AX_ACCEL (axis acceleration)
to make sure that the drive does not reach its current limit when accelerating
and decelerating.
The K factor must also be checked for high speeds of the rotary axis and
V
spindle (e.g. for spindle positioning, tapping).
The approach behavior at various speeds can be checked by means of a stor-
age oscilloscope or the HMI Advanced servo trace software. The speed set-
point is recorded for this purpose.
n
set
[V]
t [ms]
No overshoots may occur while the drive is approaching the static states; this
applies to all speed ranges.
The reasons for an overshoot in the control loop can be:
S
Acceleration too high (current limit is reached)
S
Rise time too long (re–optimization necessary)
S
Mechanical backlash
S
Mechanical components canted
For safety reasons, set the K
value.
The real K factor must precisely match that set because monitoring functions
V
are derived from the K factor that would otherwise respond (e.g. contour moni-
V
toring).
The machine axes are accelerated and decelerated with the acceleration en-
tered in
S
MD32300: MAX_AX_ACCEL (axis acceleration)
This value should allow the axes to be accelerated and positioned rapidly and
accurately while ensuring that the machine is not unduly loaded.
The default values of the acceleration are in the range from 0.5 m/s
"Well"
selected KV factor
factor to a little less than the maximum possible
V
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
01/2007
t [ms]
2 2
to 2 m/s