4. INTERPOLATION FUNCTIONS
One of the X–, Y–, and X–axes can be specified as a hypothetical axis.
Although the axis specified as a hypothetical axis does not allow
operation by any subsequent program commands, interpolation is
performed internally. If, therefore, one circular interpolation axis is
specified as a hypothetical axis, circular interpolation is performed on the
remaining one axis only, allowing the feedrate to be changed in a sine
When circular interpolation is performed on the Y– and Z–axes with the
Z–axis specified as a hypothetical axis, it is possible to machine the
corners of a rectangular pipe placed in parallel with the X–axis by
applying gap control to the Z–axis and rotating the rectangular pipe about
a helical axis.
G07 α0 ; Sets a hypothetical axis.
G07 α1 ; Cancels a hypothetical axis.
where, α is any of the addresses on a controlled axis.
When hypothetical axis interpolation mode is set by executing the G07
0 command, the axis specified as a hypothetical axis does not allow
operation by any program instructions other than gap control commands.
Thus, the machine, absolute, and relative coordinates are not updated.In
hypothetical axis interpolation mode, interpolation is performed on those
axes including the hypothetical axis. In the block where the hypothetical
axis is specified, therefore, the speed of the nozzle end point will not be
The G07 1 command cancels hypothetical axis interpolation mode; in the
coordinate system with the axis specified as the hypothetical axis,
operation is restarted with the values assumed before hypothetical axis
interpolation mode was set.
Sine interpolation is possible by performing pulse distribution with one
of the circular interpolation axes subject to helical interpolation used as
a hypothetical axis.
If helical interpolation is performed on the YZ plane with the Z axis
specified as a hypothetical axis, sine interpolation is performed on the X–
and Y–axes. In sine interpolation on the YZ plane in one cycle, the
hypothetical axis is the X axis.
Y + rSIN
where r is the arc radius.
where l is the amount of movement on the
Z–axis in one cycle.
D Sine interpolation