
4. SERVO FUNCTION DETAILS B-65150E/04
− 140 −
<4> Switch the NC off, attach the servo check board, then switch the
NC on again. ⇒ See Sec. 4.19.
Run a program to operate the axis for cutting feed at maximum
feedrate. Under this condition, check whether the VCMD
waveform observed between channels 1 and 3 on the servo check
board overshoots and what the shock caused during acceleration
/deceleration is like.
⇒ If an overshoot occurs, or the shock is big, increase the
acceleration/deceleration time constant, or reduce α.
⇒ If an overshoot does not occur, and the shock is small, reduce
the acceleration/deceleration time constant, or increase α.
Linear acceleration/deceleration is more effective than
exponential acceleration/deceleration.
Using acceleration/deceleration before interpolation can further
reduce the figure error.
<5> By setting the parameter below, the feed-forward function can be
used for cutting feed as well.
#7 #6 #5 #4 #3 #2 #1 #0
1800
−
FFR
1800
−
FFR (#3) Specifies whether feed-forward control during rapid traverse is enabled
or disabled.
1: Enabled
0: Disabled
By using the feed-forward function during rapid traverse, the
positioning time can be reduced. On some machines, however, a
shock may occur at the time of acceleration/deceleration. In such
a case, use fine acceleration/deceleration (⇒ Subsec. 4.8.3) at the
same time, or make adjustments such as increasing the
acceleration/deceleration time constant.
By using the cutting feed/rapid traverse switchable fine
acceleration/deceleration function at the same time, a feed-
forward coefficient can be set separately for cutting feed and rapid
traverse. (See Subsec. 3.4.2, "Cutting Feed/Rapid Traverse
Switchable Function" and Subsec. 4.8.3 "(5) Setting parameters
for the fine acceleration/deceleration function, used separately for
cutting and rapid traverse.")