December 2001 The Control Loop 6 – 109
6.8 The Control Loop
Machine tools normally function on the principle of cascade control. Here the
position control loop is prior to the speed and current control loops.
Benefits of cascade control:
n Transparent structure of the individual control loops.
n Disturbances can be compensated through the subsequent controllers. This
relieves the prior controller.
n The respective outer control loop protects the inner control loop by limiting
the command variable.
n Individual commissioning of each control loop, starting with the innermost
loop.
TNC 426 CB,
TNC 430 CA
The position control loop is integrated in the TNC.
The speed controller, current controller and power supply unit are located in
the servo amplifier.
The nominal speed command signal is sent by the TNC to the servo amplifier
through an analog ±10-V interface.
The TNC 426 CB has an analog nominal speed command interface and
controls machines with up to 5 axes plus spindle.
The TNC 430 CA has an analog nominal speed command interface for
machines with up to 8 axes plus spindle. A further axis can be controlled with
an additional PCB.
Note
In the TNC 426 CB, TNC 430 CA there are no machine parameters for
speed and current controllers.
For instructions on adjusting these controllers, refer to the description of
your servo amplifier.
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