
19. FUNCTIONS FOR HIGH SPEED
CUTTING B–63682EN/01
NC FUNCTION
134
The machine is accelerated/decelerated automatically when the
movement is started/stopped, so that the machine system should not be
applied with any shock. When programming, therefore, no consideration
needs to be made for acceleration/deceleration.
Especially when performing the high–speed arc cutting, however, the
actual tool passage may bring about some error against the designated arc
during circular interpolation due to this automatic acceleration/
deceleration.
This error can approximately be given by the following formula;
Command path
Actual path
Dr +
1
2
(T
1
2
) T
2
2
)
V
2
r
r
Y
X
∆r : Maximum value of radius error (mm)
v : Feedrate (mm/sec)
r : Circular radius (mm)
T
1
: Exponential acceleration/deceleration time constant (sec)
T
2
: Time constant of servo motor (sec)
(1). . . . . . . . . . . .
∆r
When performing the actual machining, the actual arc machining radius
(r) and tolerance (delta r) are given, therefore, the maximum permissible
speed v (mm/min.) can be given by the formula–(1).
“Feedrate clamp by circular radius” is such function that the circular
cutting feed is automatically clamped when the feedrate designated may
exceed the permissible tolerance to radial direction against the circular arc
having optional radius designated by the program.
19.2
FEEDRATE CLAMP
BY CIRCULAR
RADIUS