L974 1-Point Measurement With Reversal - Siemens SINUMERIK 840 User Manual

4 Measuring Cycles for Turning Machines

4.3.3 L974 1-point measurement with reversal

4.3.3 L974 1-point measurement with reversal
Function and application
The measuring cycle ascertains the actual value of the workpiece in the selected measuring
axis in relation to the workpiece zero point and the set/actual difference.
The workpiece is positioned to the value of R26 (start angle) prior to the first measurement
using M19. The second measurement is preceded by a reversal through 180°. The measure-
ment with reversal compensates any possibly existing eccentricity of the workpiece caused by
a chuck with three jaws. The actual value and the set/actual difference are determined on the
basis of the two measurements.
An empirical value stored in SDC is subsequently allowed for with the correct sign.
In addition, averaging is performed over several parts and the tolerance bands are checked
(Section 1.7.1).
The probe is located at a distance "a" facing the measuring surface on completion of
measurement.
No automatic compensation or a length compensation is carried out, depending on the defi-
nition of R10.
Preconditions :
• The probe must have been calibrated in the direction of measurement.
• The probe must be positioned with tool offset and G53 to face the surface to be
measured (Fig. 4.9).
• The maximum diameter that can be measured depends on the traversing range of the
turret slide in +X.
• M19 oriented spindle stop with axis movement must be defined.
Outside diameter:
D = 2×(X
max MFmax
Inside diameter:
D = 2×(X
max MFmax
4–30
_ _
X ) + 2a
F ball
_ _ _
X ) 2a
F ball
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Siemens AG 1990 All Rights Reserved
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SINUMERIK 840/850/880 (BN)