
PROGRAMMING
B–63614EN/01
19. HIGH SPEED CUTTING
FUNCTIONS
369
(3)Feedrate clamp based on acceleration
As shown below, when a curve is formed by very short successive line
segments, there is no significant feedrate difference along each axis at
each corner. Consequently, the tool need not be decelerated to compensate
for feedrate differences. When taken as a whole, however, successive
feedrate differences generate a large acceleration along each axis.
In this case, the tool must be decelerated to minimize the stress and strain
imposed on the machine, as well as the machining error that may result
from such excessive acceleration. The tool is decelerated to the feedrate
at which the acceleration along each axis, found from the formula below,
is equal to or less than a specified allowable acceleration.
The allowable acceleration is determined from a maximum cutting
feedrate (set in parameter No.1432) and the time needed to reach the
maximum cutting feedrate (set in parameter No.1785).
Acceleration along each axis =
feedrate difference along each axis at a corner
max
ǒ
travel in the previous block
F
,
travel in the next block
F
Ǔ
The reduced feedrate required for each corner is calculated. The tool is
decelerated to the decreased feedrate found at either the start point or the
end point of each block, whichever is smaller.
(Example)
In the example shown below, the tool is decelerated from N2 to N4 and
from N6 to N8 because the acceleration (as indicated by the dashed–line
inclinations in the feedrate graphs) is large.
N9
N5
N1
N2
N3
N4
N6
N7
N8