Fagor CNC 8065 - Page 455

Installation manual
CNC 8060
CNC 8065
CONCEPTS.
9.
(REF: 1402)
·455·
Configure two axes as a tandem axis.
Tandem axis control.
The block diagram showing the application of the tandem axis control is the following. The
meaning of the nomenclature being used is:
Torque of the master motor of the tandem.
It is the percentage of the rated torque shown by the sercos variable TV2 of the drive that
governs the master axis of the tandem. It is read through the sercos fast channel in each loop.
Torque of the slave motor of the tandem.
It is the percentage of the rated torque shown by the sercos variable TV2 of the drive that
governs the slave axis of the tandem. It is read through the sercos fast channel in each loop.
Torque distribution.
Normalizing gain of the torque generated by the motors in order to distribute the torque in
a ratio other than 1:1.
Preload.
Previous torque applied to both tandem axes in opposite direction. This sets a traction
between them in order to eliminate the rack-and-pinion backlash when it is in rest position.
It is determined as the torque difference supplied by each axis.
Preload filter.
First-order filter to prevent torque steps from coming in when configuring the preload.
PI of the tandem.
PI for making each motor provide its corresponding torque. It increases its velocity command
if the torque being supplied is too low and it decreases it if the torque being supplied is too
high.
When defining a tandem axis, at each loop, the CNC reads via Sercos the torque supplied
by the master and the slave axes. This may result in a smaller number of read and write
variables available in the Sercos fast channel.
Applying the preload necessarily implies mechanically joining the master and slave axes that make
up the tandem axis. Otherwise, the motors will move even without the control velocity command.