Siemens SINUMERIK 840C - Manual (Page 827)

12 Functional Descriptions 10.94
12.7.2 Description of the spindle modes
When speed n
x
is set to the same value as limit speed n
max
or when "0" (default setting) is
input, the acceleration characteristic is the same as that obtained with previous software
versions, i.e. without characteristic curvature (break point above maximum speed).
When "1" is entered for adaptation factor c, the acceleration rate is reduced according to the
speed value reciprocal (1/n) above limit speed. This reduction rate can be increased
("steeper" acceleration characteristic) or decreased ("flatter" acceleration characteristic) as
required by entering values lower or greater than "1" (i.e. 100 %).
In M19 operation, the search speed is limited internally to n
x
.
With the exception of the parameter set extension, the acceleration response obtained with
previous software versions is still only available in C-axis operation, i.e. it is not possible to
adapt the acceleration rate to the speed value.
It is not necessary to parameterize the characteristic for spindles which are not operated in
synchronous groupings or which are equipped with feed drives.
As with previous software versions, the acceleration characteristic is parameterized by the
user according to technological requirements. In this case, analog and digital drives are treated
in the same way. Automatic adjustment using drive data (e.g. breakdown limit) does not take
place. It is thus possible to set the load side parameters (acceleration characteristic) and the
drive side parameters (protection of motor and power section) independently.
The "Curved acceleration characteristic for spindles" is operative in the following spindle
operating modes:
• Open-loop control mode (M3, M4, adjust PLC):
The setpoint speed is specified according to the "Curved acceleration characteristic" when
the position controller is active at the same time (main application: Leading spindle in
synchronous spindle group).
• Positioning mode (M19, positioning from PLC or command channel):
The maximum positioning speed is limited to nx ("Limit at which acceleration adaptation
takes effect", MD 2471*).
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SINUMERIK 840C (IA)