Siemens SINUMERIK 840D sl Programming Manual page 208

Fundamentals
2.9 Motion commands
AR=... :
Indirect programming of the end point by specifying an opening angle
NOTICE
Opening angle undefined
When the end point is indirectly programmed by specifying an opening angle AR, the sign of
the angle must be taken into account, as a sign change would result in another involute and
therefore another path.
This is demonstrated in the following example:
The specifications of the radius and center point of the basic circle as well as the starting point
and direction of rotation (INVCW/INVCCW) are the same for involutes 1 and 2. The only
difference is in the sign of the opening angle:
● With AR > 0, the path is on involute 1 and end point 1 is approached.
● With AR < 0, the path is on involute 2 and end point 2 is approached.
208
Indirect programming of the end point by specifying an opening angle
(angle of rotation)
The origin of the opening angle is the line from the circle center point
to the starting point.
AR > 0: The path of the involute moves away from the basic cir‐
cle.
AR < 0: The path of the involute moves towards the basic circle.
For AR < 0, the maximum angle of rotation is restricted
by the fact that the end point must always be outside the
basic circle.
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming