Siemens SINUMERIK 840D Function Manual page 803

t :
4
t :
5
* :
Figure 18-7
gear stage change position MD35012
The gear stage change position is defined in machine data:
MD35012 $MA_GEAR_STEP_CHANGE_POSITION
for each gear stage.
Gear stage change wait time MD35310
After the positioning action the machine waits for the time configured in machine data:
MD35310 $MA_SPIND_POSIT_DELAY_TIME
until gear change request:
DB31, ... DBX84.6 (oscillation mode)
DB31, ... DBX82.3 (change gear)
and
DB31, ... DBX82.0-82.2 (set gear stage A to C)
are output.
Position identifiers / position
The position is always approached via the shortest path (corresponds to DC).
If no reference is available and the spindle is in standstill
(e.g. after Power On), then the direction of travel is determined by the following machine data:
MD35350 $MA_SPIND_POSITIONING_DIR
If an adjustable gear stage change position is required, then this can be achieved by writing the
machine data and by a subsequent "Activate machine data".
The change of the MD value can be achieved by the part program or HMI.
If the system is unable to reach the preset position, then alarm 22020 is signaled and the gear
stage change dialog between NC and PLC does not take place in order not to destroy the gears.
As this alarm is serious, the part program cannot continue and the cause must be eliminated
under all circumstances. Experience has shown that the abortion of positioning is usually due
to incorrect MD settings or incompatible PLC signals.
Velocity
The positioning velocity is taken from the machine data which is configured depending on the
gear stage:
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
The new gear stage is engaged. The PLC user transfers the new (actual) gear stage to the NC
and sets IS DB31, ... DBX16.3 (gear is changed).
The NC then retracts IS DB31, ... DBX82.3 (change gear), releases the next part program block
for processing, and accelerates the spindle to the new S value (S1300).
The internal feed disable is set if:
● The spindle gear stage change has been programmed via the part program and
● A processing block is activated (i.e. G0 is not active)
The internal feed disable is not set during a gear stage change from synchronized actions or in the
case of specifications via the PLC with FC 18.
Gear stage change with stationary spindle
S1: Spindles
18.4 Configurable gear adaptations
803