
B-63944EN/02 PROGRAMMING 4.INTERPOLATION FUNCTIONS
- 69 -
- Cutter compensation
M
The spiral or conical interpolation command can be programmed in
cutter compensation mode. This compensation is performed in the
same way as described in "When it is exceptional" in "Tool Movement
in Offset Mode" section. A virtual circle centered on the center of
spiral interpolation is thought at the end of a block. The tool path is
obtained by performing cutter compensation along the virtual circle
and the blocks before and after the spiral interpolation. When the end
point of the block is at the center of the spiral interpolation, no virtual
circle can be drawn. If drawing is attempted, an alarm PS5124 is
issued.
Programmed spiral
interpolation
Virtual circle
Tool center path
r
r
Center
After cutter
compensation
- Actual cutting feedrate
A constant speed is maintained in spiral interpolation or conical
interpolation. The angular velocity near the center, however, may
increase because of the small radius of the spiral. This can be avoided
by maintaining the angular velocity after the radius of the spiral
reaches a value specified in parameter No. 3472. Consequently, the
actual cutting feedrate decreases.
An example is illustrated below.
Specified feedrate: F100.
Parameter 3472 (r) = 1.000
IS-B
While the radius of the spiral shown
at the left is greater than the value
specified in parameter No. 3472, the
actual cutting feedrate is F100. As
the radius decreases, the actual
feedrate also decreases, the actual
feedrate near the end point being
about F65.
r
1.5
-0.5