
B-65270EN/05 4.SERVO FUNCTION DETAILS
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(2) Back-feed confirmation method
“Back-feed” means the feasibility that the axis can be driven not only
from motor side but also from machine table side.
(a) Check whether back-feed is possible when the machine is
connected and the power line is removed.
If back-feed is impossible, unstable control will result, and
machine adjustment such as a gear box adjustment will be
necessary.
<1> Making a check manually
First, turn the shaft of the main motor manually to check
that the sub-motor turns. Next, turn the shaft of the
sub-motor manually to check that the main motor turns. If
these checks are successful, back-feed is possible.
<2> Making a check using NC commands
After checking (b) and (c) below, remove the sub-motor
power line. Then, enter a plus (+) command or minus (-)
command to rotate the main motor. Check that the main
motor can be turned with one-third or less of its rated static
torque. When this check is successful, back-feed is possible.
(b) With the machine connected, activate the motors. At this time,
release the emergency stop state after reducing the torque limit
by a factor of about 10.
Check the motor current on the servo adjustment screen. If the
current increases gradually, the directions of rotation of the main-
and sub-motors may not be set correctly.
(c) Check the operation by entering a plus (+) command and minus
(-) command.
If the error persists due to friction load, increase the torque limit.
(d) If the operation is normal, return the torque limit to its original
value, and then set a preload value.