
3.INTERPOLATION FUNCTION PROGRAMMING B-63944EN-2/02
- 24 -
3.1.1 Automatic Speed Control for Involute Interpolation
This function automatically overrides the programmed feedrate in two
different ways during involute interpolation. With this function, a
favorable cutting surface can be formed with high precision.
• Override in cutter compensation mode
• Override in the vicinity of basic circle
- Override in cutter compensation mode
When cutter compensation is applied to involute interpolation, control
is exercised in ordinary involute interpolation so that the tangential
feedrate on the tool-center path always keeps the specified feedrate.
Under the control, the actual cutting feedrate (feedrate around the
perimeter of the tool (cutting point) on the path specified in the
program) changes because the curvature of the involute curve changes
every moment.
If the tool is offset in the inward direction of the involute curve in
particular, the actual cutting feedrate becomes higher than the
specified feedrate as the tool gets nearer to the base circle.
For smooth machining, it is desirable to control the actual cutting
feedrate so that the feedrate keeps the specified feedrate. This
function calculates an appropriate override value for the
ever-changing curvature of the involute curve in the involute
interpolation mode after cutter compensation. The function also
controls the actual cutting feedrate (tangential feedrate at the cutting
point) so that it always keeps the specified feedrate.
Path specified in
the program
Base
circle
Cutting point
Rcp
Rofs
Fig. 3.1 (d) Override for inward offset by cutter compensation