Siemens SINUMERIK 840D sl Programming Manual page 151

Internally, the actual center point of circle XY is determined from these measured values
(ball center in the plane). Then with +Z and in XY, the axis traverses to the calculated "north
pole" of the ball. There, a measurement is made in -Z.
The complete center point of the sphere is calculated in the three axes of the plane (XYZ)
from the measuring points.
In the case of a repeat measurement, the axis traverses to the precise equator of the ball
(from the 1st measurement); this improves the measurement result.
If, in addition to the ball center point, also the actual ball diameter is to be measured, then
the cycle performs a supplementary measurement parallel with the axis at the equator in the
+X direction.
The "Positioning on a circular path" measuring version should be preferably used, because
this permits optimum positioning behavior. In addition, with this measuring version, when
circling around the ball, the probe can be aligned in the switching direction (see the "align
probe" parameter).
Correction in a work offset (WO)
The set-actual differences of the center point coordinates are calculated in the translatory
part of the WO. During the correction, the determined sphere center point includes the
specified setpoint position (workpiece coordinates, three axes) in the corrected WO.
Preconditions
● The probe must be called as a tool with tool length compensation and be active.
● Tool type of the probe: 3D multi probe (type 710)
● The ball diameter must be significantly greater than the ball diameter of the probe stylus.
Starting position before the measurement
The probe must be positioned above the set sphere center point at a safe height.
The measuring cycle generates the traversing motion for approaching the measuring points
itself and performs the measurements depending on the measuring version selected.
Note
The ball to be measured must be mounted in such a way that when positioning the probe,
the equator of the probe ball of the measuring object can be reliably reached in the
workpiece coordinate system and no collision with the ball clamping occurs. By specifying a
variable starting and incremental angle, when positioning on a circular path, this is also
possible under difficult clamping conditions.
The measurement path in parameter DFA should be selected so large that all measuring
points can be reached within total measurement path 2 DFA. Otherwise no measurement
can be performed or the measurements are incomplete.
Measuring cycles
Programming Manual, 02/2011, 6FC5398-4BP40-0BA0
The sum of starting angle α0 and all incremental angles α1 must not exceed 360
degrees! An angular range of ± 360 degrees permitted for the starting angle.
Measuring variants
2.3 Measure workpiece (milling)
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