Tandem Adjustment Procedure - Fagor CNC 8060 Installation Manual

11.2.5
11.
CNC 8060
CNC 8065
(R : 1709)
EF
·560·

Tandem adjustment procedure.

This procedure must bear in mind the type of machine. In general, the resonance frequency
of a tandem machine is low; therefore, the CNC must generate position commands without
frequency components higher than the resonance frequency.
It is recommended to begin the process with low jerk values (lower than 10 m/sec3) and low
Kv. They can always be increased in a later readjustment.
Steps for the adjustment.
1 Move both axes independently.
The first step is to ensure the perfect operation of both the master and the slave axes
separately. Also verify that both axes move in the same direction with similar dynamics.
2 Move one of the axes at a slow and constant speed.
• Do not make jerky movements because the second motor is being dragged by the
first one. In this situation, any acceleration or deceleration forces it to go from one
side of the backlash to the other thus making it jerky.
• Verify that the turning direction of both motors are coherent once the movement has
been carried out.
i
Observe that reversing the turning direction of a motor reverses the direction of the torque and,
consequently, it will be necessary to change the direction of its values monitored with drive parameters
SP43 and TP85.
• Verify that the gear ratio in both motors is the same (same feed for same turning
speed).
• Carry out a basic adjustment of the velocity loop so the machine can move. It will be
readjusted later with both motors together.
• Do not set the friction parameters (there is already enough torque to move the
machine).
3 Repeat the procedure with the second axis.
When adjusting the loops, use the same parameters if the motors are identical and the
torque distribution is 50%. If the motors are different, the axes must be adjusted so their
dynamic response is the same or very similar. When using AC-forward ("ACFGAIN" =
YES), remember that each motor has half the inertia for a 50% torque distribution.
4 Enable the tandem with both motors.
First, disable the PI of he tandem, apply power and verify that the system is at rest.
Then, enter a low proportional value and eliminate the integral value of the PI of the
tandem. Without preload, verify that the machine moves and that each motor supplies
its corresponding torque according to the parameter "TORQDIST" (e.g. half the torque
for 50% distribution).
To define the pre-load, monitor the torque of each motor (Sercos variable TV2). While
stopped, increase the preload gradually until the motors supply torque in opposite
directions.
Having enabled the tandem, move slowly in both directions and verify that it works
properly. Make sure that it is not jerky and that each motor supplies its corresponding
torque according to parameters "TORQDIST" and "PRELOAD".
Finally, readjust the velocity loop in both motors with the method used normally.
i
While changing the parameters of the velocity loop, the best thing would be to change them on both
drives at the same time. But, since this is not possible, it is recommended to make small changes in
the values or make them while the motor is stopped.
I n s ta ll a t io n ma n u a l.