
B–63523EN–1/03
7. FEEDRATE CONTROL/ACCELERATION
AND DECELERATION CONTROL
861
Acceleration/deceleration is performed as described below when the
feedrate is changed.
Deceleration: In order to end deceleration before entering into a block that
changes the feedrate, bell–shaped deceleration is
performed starting with the previous block.
Acceleration: After entering into a block that changes the feedrate,
bell–shaped acceleration/deceleration is started.
Fa
Fb
Fb
Fa
N1 N2
N1 N2
Deceleration
Time
Time
Acceleration
Feedrate
When there are axes for which the difference in feedrate between blocks
exceeds the allowable feedrate difference set in parameter 1783, the
automatic corner deceleration function calculates the feedrate at a corner
and performs deceleration so that the calculated feedrate is attained at the
junction of the blocks. The feedrate at the corner is calculated as
explained below, where the ratio of the difference in the actual feedrate
to the allowable feedrate difference is obtained for each axis, after which
the largest of these ratios is used as a reference.
The change in feedrate on each axis (Vx, Vy, ...) when the tool moves at
a specified feedrate F is compared with the value set in parameter 1783
(Vprm–x, Vprm–y, ...). If the change in the feedrate for any axis exceeds
the parameter–set value, the following is obtained first:
Rmax = max
Vx
Vprm–x
Vy
Vprm–y
,
, . . .
Then, the feedrate (Fc) is obtained from the following expression, after
which corner deceleration is performed:
Fc = F
1
Rmax
For example, suppose that the direction of the tool movement changes
through 90 degrees from X–axis movement to Y–axis movement, and
also suppose that the specified feedrate is 1000 mm/min, and that the
allowable feedrate difference (parameter 1783) is set to 500 mm/min.
Then, deceleration is performed as shown in the figure below.
Automatic corner
deceleration