PROGRAMMING
B–63534EN/02
19. HIGH SPEED CUTTING FUNCTIONS
467
When an arc is cut at a high speed in circular interpolation, a radial error
exists between the actual tool path and the programmed arc. An
approximation of this error can be obtained from the following
expression:
0
Y
X
r
∆r:Error
∆r : Maximum radial error (mm)
v : Feedrate (mm/s)
r : Arc radius (mm)
T
1
: Time constant (s) for exponential acceleration/deceleration of
cutting feed
T
2:
Time constant of the servo motor (s)
∆r= (T
1
2
+T
2
2
)
2
1
r
v
2
Programmed path
Actual path
When actual machining is performed, radius r of the arc to be machined
and permissible error Dr are given. Then, maximum allowable feedrate
v (mm/min) is determined from the above expression.
The function for clamping the feedrate by the arc radius automatically
clamps the feedrate of arc cutting to the value set in a parameter. This
function is effective when the specified feedrate may cause the radial
error for an arc with a programmed radius to exceed the permissible
degree of error.
For details, refer to the relevant manual published by the machine tool
builder.
19.2
FEEDRATE
CLAMPING BY ARC
RADIUS