Siemens SINUMERIK 828D Function Manual page 360

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G2: Velocities, setpoint / actual value systems, closed-loop control

7.4 Setpoint/actual-value system

Intermediate gear

Additional, configurable load intermediate gears are also supported by the control:

MD31066 $MA_DRIVE_AX_RATIO2_NUMERA (intermediate gear numerator)

MD31064 $MA_DRIVE_AX_RATIO2_DENOM (intermediate gear denominator)

Power tools generally have their "own" intermediate gear. Such variable mechanics can be configured by

multiplying the active intermediate gearbox and the motor/load gearbox.

Unlike the motor/load gear, there is no parameter set for the intermediate gear and,

therefore, no way of controlling the time-synchronized switchover to parts program or PLC

(VDI interface). Part programming during gear change is, therefore, ruled out. It remains the

task of the user to match the synchronization of the relevant changed machine data to the

corresponding mechanical switchover and activate it. On switchover during a movement,

compensations cannot be ruled out due to jumps in the scaling factors. These are not

monitored for violation of the maximum acceleration.

Encoder directly at the tool

Another connection option is possible for a "tool-side encoder" on the intermediate gear, by configuring machine

MD31044 $MA_ENC_IS_DIRECT2

Encoder not directly at the tool

The following supplementary conditions apply to a gear change of the intermediate gear in position-control mode:

The gear ratio to be changed is incorporated in a re-scaling of the encoder information in this case.

In this case, the following applies to axes/spindles in positioning mode:

A non-abrupt gear change is only possible at zero speed.

To do this, the tool-side position before and after a gear change are set equal for a change in the ratio, since

the mechanical position does not (or hardly) changes during a gear stage change.

Recommendation:

To avoid 21612 "Controller enable reset during motion", changeover should be carried out "only at zero

speed". It is still permissible and expedient to switch the axis or spindle to speed-control or follow-up mode

before or during a gear change.

Boundary conditions

If the encoder to be used for position control is connected directly at the tool, the gear stage change only affects

the physical quantities at the speed interface between the NC and the drive of the motor/load gear. The internal

parameter sets are not changed.

Function Manual, 09/2011, 6FC5397-0BP40-2BA0

Basic Functions

Sinumerik 840d sl