Drift Compensation - Siemens SINUMERIK 840C Installation Instructions Manual

10 Axis and Spindle Installation 09.95
10.4.1 Drive optimization
In addition to the values set in machine data NC MD 252* (servo gain) and NC MD 260*,
1200* (multgain), the servo gain is also influenced by the tachogenerator compensation in the
speed controller (for analog), by the variable increment weighting and by gear ratios etc.
NC MD 332*, MD 256* and 336* are used to influence the contour monitoring.
The tolerance band defining the range of activity of the contour monitoring is specified in NC
MD 332*.
The speed from which the contour monitoring is to take effect is entered in NC MD 336* in
1000 units/min (IS). If the value 0 is entered, the contour monitoring is also active when the
axis is at zero speed. The zero-speed monitoring also checks for excessive axis movement
when the axes are at zero speed.
Deviations from the contour at any one time can be displayed for the individual axes in the
diagnostics menu under softkey "SERVICE DISPLAY".
When the monitoring is triggered, alarm 116* is output and the drives are decelerated at the
current limit with the output of setpoint value "0". The speed controllers are also disabled and
switched to follow-up mode. The alarms can only be cleared with "RESET" (MD/M30).
If alarm 116* is output it can be assumed that either the speed control loop has been poorly
optimized, the servo gain factor is too large for the machine or the tolerance band is too small.
10.4.2

Drift compensation

Drift compensation is semi-automatic on the SINUMERIK 840C, as it must be initiated by the
operator. Drift compensation can be performed when the axes (of the NC) and the drives are
operating in closed-loop control mode and the axes are at rest.
Drift compensation has to be carried out if the drift has exceeded the permitted values defined
in MD 204* and 208*.
Drift compensation must be carried out for all axes individually.
Drift compensation can also be carried out manually by changing the value in MD 272* until the
following error at zero speed has reached zero (check service data for axes).
When very high precision machines are used, drift compensation should
be performed several times daily because of the variations in
temperature during operation as the drift is a direct factor in terms of
the following error.
Selection of drift compensation (up to SW 2)
Use the DIAGNOSIS/NC DIAGNOSIS/SERVICE DISPLAY softkeys.
Selection as from SW 3
Use the DIAGNOSIS/SERVICE DISPLAY/NC DIAGNOSIS softkeys.
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© Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)
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