
20. FUNCTIONS FOR HIGH SPEED
CUTTING B–63522EN/02
NC FUNCTION
274
Machining errors by CNC include those caused by acceleration/
deceleration after interpolation. To prevent such errors, the RISC
processor provides the following functions:
D Acceleration/deceleration before interpolation by pre-reading
multiple blocks. Because executed before interpolation,
acceleration/deceleration does not cause a machining error.
D Automatic velocity control by smooth acceleration/deceleration. By
pre-reading multiple blocks, changes in the profile and speed, and the
allowable acceleration of the machine can be taken into consideration
to execute smooth acceleration/deceleration.
Smooth acceleration/deceleration increases the feed-forward coefficient.
As a result, the tracking error of the servo system can be reduced.
When cutting feed per minute is specified, tens of blocks are pre-read. The
linear acceleration/deceleration is executed for the command speed
before interpolation.
If acceleration/deceleration is executed after interpolation, the
interpolation data is changed.
If it is executed for the feedrate before interpolation, the interpolation data
is not affected.
Since the interpolation data can always be placed on the specified line or
curve, there will be no machining profile error caused by
acceleration/deceleration.
Linear
acceleration/
deceleration
before
interpolation
Feedrate
calculation
Interpolation
calculation
Servo
control
Velocity
com-
mand
Distribu-
tion
pulse Acceleration/
deceleration
after interpolation
Linear, exponential
function, bell type
Linear interpolation,
circular interpolation,
etc.
Linear bell type
A change in feedrates for each axis on the junction of two blocks (corner
section) may be greater than the value set in the parameter. In such a case,
the appropriate feedrate (reduced speed) is calculated so that the change
is within the set value at the corner. The feedrate in the former block
automatically reduces to the calculated value.
20.6
HIGH–PRECISION
CONTOUR CONTROL
(ONLY AT ONE–PATH)
(M series)
M series
20.6.1
Acceleration/Decelera-
tion Before Interpola-
tion by Pre-reading
Multiple Blocks