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

M3: Coupled axes
14.5 Generic coupling
Response of the following spindle
If a rapid stop is detected for a leading spindle and the following spindle does not execute any
rapid stop by itself, then the following spindle tries to follow the dynamics of the movement of
the leading spindle defined within its framework. As position synchronization is generated,
there may be oscillations in the following axis in relation to the position to be approached.
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.
14.5.13

Tracking the deviation from synchronism

14.5.13.1

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.
558
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA