Installation manual
CNC 8055
CNC 8055i
CONCEPTS
7.
SOFT: V02.2X
·301·
Axes and coordinate systems
Configuration of the tandem axis
When configuring a tandem axis, bear in mind the following requirements.
• Each master tandem axis admits one single slave tandem axis.
• The axes must be "velocity Sercos".
• A preload may be applied between the two motors.
• Each motor may have a different rated torque.
• The turning direction of each motor may be different from the other's.
• The torque distribution between both motors may be different from 1:1 ratio. For example, on
motors whose rated torque is different.
• It is not possible to share feedback or velocity commands using the switch parameters on axes
having a tandem configuration.
A tandem axis is configured by the machine parameters of the master axis. The slave axis does
not have an axis table at the CNC, although it is possible to access the parameter and variable tables
of the slave axis drive. It is accessed from the machine parameters > drive.
Axis parameter TANSLAID (P76) enables the tandem parameters. If this parameter is zero, there
is no tandem axis and it ignores the values of the rest of the tandem control parameters.
Selection of the master and slave axes
The axis whose table sets the parameters will be the master axis of the tandem. The slave axis of
the tandem is set using parameters TANSLAID (P76) and TANSLANA (P77).
Parameter TANSLAID (P76) indicates the Sercos ID of the slave axis. This parameter determines
the drive that will generate the velocity command of the slave axis.
Parameter TANSLANA (P77) determines the name of the slave axis. This parameter is used to
identify the PLC marks, identify at the CNC the errors and identify the parameter tables of the drive.
Torque and pre-load distribution
The torque distribution determines the torque supplied by each motor in order to obtain the
necessary total torque on the tandem axis. It is set with parameter TORQDIST (P78).
Pre-load is the torque difference to be applied between the two motors, so as to establish a traction
between them in order to eliminate backlash. It is set with parameters PRELOAD (P79) and
PRELFITI (P80).
Parameter PRELOAD (P79) sets the pre-load value and parameter PRELFITI (P80) sets the filter
time to apply it. The pre-load is applied progressively during the time indicated in the filter, thus
avoiding a step (shoulder) in the velocity command of the axes.
Gain setting
The proportional gain is set with parameter TPROGAIN (P81). The proportional controller generates
an output proportional to the torque error between the two motors.
The integral gain is set with parameter TINTTIME (P82). The integral controller generates an output
proportional to the integral of the torque error between the two motors.
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.
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