CNC Motion Setup/Testing Utility
P/N 70000635C
All rights reserved. Subject to change without notice.
November 2009
30
. Line 5 indicates:
nodes.
6 icate the I/O status of any additional nodes.
Rigid Tapping Test
This test displays the lag between the spindle and the Z-axis velocity as a
measurement of synchronization between the mentioned axes. The
display units are microns per position loop sample. After the test is
selected, a Rigid Tapping Cycle must be programmed using Manual Data
In
The lag display has 3 main sections:
a) Going in
b) Reversing direction (retract)
c) Going out the thread
If the controller is optimally tuned, the sections [a] and [c] should present
ns that either the spindle
l speeds. The most critical
en reversing direction. This
lag will increase proportionally to the spindle rpm and it may be
diminished by fine-tuning the rigid tapping gains of the Proportional
Integral Derivative (PID) controller in the Z-axis (proportional gain [Kp]
and feedforward gain [Kf]). As a point of reference, the threading
(sections [a] and [c]), the retract lag (section [b]), and the Z-axis lag are
displayed on the screen after each rigid tapping cycle. Also, gains Kp
and Kf for the Z-axis can also be changed in the test before the cycle is
c ed.
s
this is d e.
5
• The status of the ten inputs of each node.
• The status of the six outputs of each node.
• Subsequent lines indicate the I/O status of any additional
. Subsequent lines ind
put (MDI).
near zero lag. Any peak on these sections mea
or Z-axis motors are not reaching their fina
section is [b] since some lag will appear wh
ommand
The best approach to fine-tune these gains is to auto-tune the PID filter
for the Z-axis with only derivative gain (Kd). After the test is done, save
these values in the rigid tapping gain table. With the help of the rigid
tapping test, start increasing Kf and/or Kp in the test until the Z-axis lag i
zero or very close to zero. Save the results with the “save” soft key after
on
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