
B–63002EN/01
5. FEED FUNCTIONS
NC FUNCTION
71
F
F/2
0
A
B
T
C
/2
T
C
T
C
Time
Feedrate
As shown above in the quadratic curve, it is possible to accelerate and
decelerate the cutting feedrate.
When the acceleration and deceleration section are connected, the
composed curve shapes just like a hanging bell. That is why this kind of
acceleration/deceleration is called bell–shaped acceleration/deceleration.
Considering a time constant as Tc (time spent to accelerate from feedrate
0 up to commanded feedrate F or time spent to decelerate from
commanded feedrate F down to feedrate 0), feedrate accelerates up to 1/2
of the commanded feedrate (F/2) for 1/2 of the time constant (Tc/2). The
acceleration/deceleration curve 0A shown in the figure above can be
expressed by the following equation :
f (t) +
2F
T
C
2
t
2
The curve AB and 0A are symmetric with respect to point A.
The feature of this acceleration/deceleration is that the feedrate change is
small near feedrate 0 and the commanded feedrate.
5.7
BELL–SHAPED
ACCELERATION/
DECELERATION
AFTER CUTTING
FEED
INTERPOLATION