Siemens SINUMERIK 840Di Function Manual page 38

Detailed Description
2.2 Functions
Limit angle
If AR is used to program an involute leading to the base circle with an angle of rotation that is
greater than the maximum possible value, an alarm is output and program execution
aborted.
Fig. 2-8
The alarm display can be suppressed with the following parameter assignment:
MD21016 $MC_INVOLUTE_AUTO_ANGLE_LIMIT = TRUE
The programmed angle of rotation is then also limited automatically and the interpolated path
ends at the point at which the involute meets the base circle. This, for example, makes it
easier to program an involute, which starts at a point outside the base circle and ends
directly on it.
Tool radius compensation
2 1/2 D tool-radius compensation is the only tool-radius compensation function permitted for
involutes. If 3D tool-radius compensation is active (both circumferential and face milling),
when an involute is programmed, machining is interrupted with alarm 10782.
With 2 1/2 D tool-radius compensation, the plane of the involute must lie in the compensation
plane. or else alarm 10781 will be generated. It is however permissible to program an
additional helical component for an involute in the compensation plane.
2-26
Limited angle of rotation towards base circle
Various NC/PLC Interface Signals and Functions (A2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0