B--63003EN--1/02
7. FEEDRATE CONTROL/ACCELERATION
AND DECELERATION CONTROL
621
For a cutting feed command in feed per minute mode, advanced preview
control of up to 15 blocks can be performed, and linear
acceleration/deceleration can be performed for a programmed feedrate
(before interpolation). When acceleration/deceleration is performed after
interpolation, acceleration/deceleration is performed for the data
resulting from interpolation, which changes the interpolation data. For
acceleration/deceleration before interpolation, on the other hand,
acceleration/deceleration is performed for the feedrate data before
interpolation, so that the interpolation data is not changed by
acceleration/deceleration. Therefore, interpolation data can always be
aligned with a specified line or curve to eliminate any machining profile
errors caused by a delay in acceleration/deceleration.
Linear acceleration/
deceleration before
interpolation
Calculation
of feedrate
Specified
feedrate
Calculation of
interpolation
Acceleration/
deceleration af-
ter interpolation
Servo
control
Pulse
distribution
Linear interpolation,
circular interpolation, etc.
(Example of deceleration)
To execute a block at a specified feedrate, the feedrate is reduced from that
of the previous block.
F3
F2
F1
N1 N2
Point 1
Point 2
Specified feedrate
Feedrate resulting
from acceleration/
deceleration before
interpolation
Feedrate
Time
To reduce the feedrate from F3 to F2, deceleration must be started at Point
1.
To decrease the feedrate from F2 to F1, deceleration must be started at
Point 2.
Since advanced preview control for up to 40 blocks is performed,
deceleration over multiple blocks can be performed.
Advanced preview linear
acceleration/deceleration
before interpolation