Tracking The Deviation From Synchronism; Fundamentals - Siemens SINUMERIK 840D sl Function Manual

M3: Coupled axes
8.5 Generic coupling
The start of a rapid stop for a leading axis/spindle is detected across NCUs.
Note
A simultaneous rapid stop of the leading and following spindle is executed in the synchronized
spindle coupling type (CPSETTYPE="COUP") during a servo alarm.
8.5.13

Tracking the deviation from synchronism

8.5.13.1

Fundamentals

Deviation from synchronism
Workpiece machining operations which are to be carried out both on the face front and the
face rear require a workpiece transfer to another workpiece receptacle (e.g. a counterspindle
chuck).
When workpieces are transferred from front to rear machining, a position offset may result
from the closing of the workpiece receptacle. This could be down to square-edged workpieces
or due to the generation of an angular momentum when the workpiece receptacle (chuck) is
closed quickly during a movement. Depending on the resistance of the workpiece, the tension
can be detected by means of an increase in the current consumption of both the motors
involved in the coupling and/or by means of the workpiece being subjected to torsion.
This could lead to the following NC/PLC interface signals being reset, according to the
synchronism tolerance which has been set, and the magnitude of the offset:
DB31, ... DBX98.1 (coarse synchronous operation) and/or
DB31, ... DBX98.0 (fine synchronous operation)
For the setpoint coupling, the position and velocity setpoints are calculated precisely in
accordance with the programmed coupling rule and output to the Control Units. If identical
drives and a rigid workpiece are used, this will lead to a regulative deviation at the leading and
following spindle, half due to a setpoint difference and half due to an actual value difference.
Function
The "track the deviation from synchronism" function serves to detect the position offset which
has been imposed on the actual value and to correct the following spindle when calculating
the setpoint.
Requirement
A coupling closed via the part/chuck must be in place in order to use this function.
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Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions