Siemens SINUMERIK 828D Programming Manual page 242

Motion commands
9.8 Involute interpolation (INVCW, INVCCW)
Indirect programming of the end point through specification of an opening angle
NOTICE
With the indirect programming of the end point through specification of an opening angle
, the sign of the angle must be taken into account, as a sign change would result in
AR
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 (
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.
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/ ) are the same for involutes 1 and 2. The only
INVCW INVCCW
Programming Manual, 07/2010, 6FC5398-1BP40-0BA0
Fundamentals