Siemens SINUMERIK 840C Installation Instructions Manual page 1004

09.95
Option for programmable emergency retraction
The function is triggered via parameterizable sources.
The response can be drive-autonomous or open-loop controlled.
The possible responses are:
• Stopping (time-controlled continuation and braking of the axis/spindles relevant to the
contour)
• Retraction (cancellation of the positive connection)
• Inversion of fast process outputs (e.g. fast cancellation of clampings).
The source
• Channels (mode group stop, inputs, emerg. OFF)
• Axis or spindle (V
dclinkmin
determines the response, i.e. the source is used to decide whether the response is to be an
autonomous function of the drive or a function of the control.
The response can be parameterized via machine data and configured via G functions.
Open-loop controlled stopping and retraction
If open-loop controlled stopping and retraction is to be used, the backup must be designed for
at least five interpolation cycles if an additional generator is not used because all axes can be
run for this time without any change.
Regenerative stopping
From the 5th IPO cycle onward, the set speeds of the configured stopping or retraction
axes/spindles are changed. Make sure that the general control machine data "Time for
interpolation-controlled continuation", NC MD 324 is set to 0. Otherwise this time must be
included additively. This is only useful if the cutting conditions must be kept as constant as
possible as long as the positive connection exists (parallel retraction).
After this time, the braking period begins. The braking behaviour and therefore the
regenerative feedback is determined by the set acceleration ramps for axes and spindles.
As soon as the braking process begins, the energy generated is available for the retraction
motion. The total energy must be calculated to ensure that the kinetic energy of the braking
axis is sufficient to perform retraction.
The total energy also tells you the maximum IPO cycle that can be set to be able to perform
safe retraction.
For example, if an emergency retraction must be possible without regenerative operation in a
16kW unit under maximum load and minimum DC link capacitance, the IPO cycle duration can
theoretically be no greater than 4.86 ms, in which case up to 4 ms can be set.
If necessary, a more powerful NCK CPU can be used to achieve optimum conditions.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
12.20.8 Configuration help for generator operation and emergency retraction
, lower speed limit, emergency retraction threshold, ...)
6FC5197- AA50
12 Functional Descriptions
12–229