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9. Adjustment
9 - 31
9-4-2 Vertical axis drop prevention control
The vertical axis drop prevention control is a function that prevents the vertical axis from dropping due to
a delay in the brake operation when an emergency stop occurs. The no-control time until the brakes
activate can be eliminated by delaying ready OFF from the servo drive unit by the time set in the
parameters when an emergency stop occurs.
(1) Operating conditions
<1> The emergency stop signal has been input.
<2> The NC power has been turned OFF.
<3> An alarm for which deceleration control is set as the stopping method has occurred. (This
differs according to the occurring alarm. Refer to "10-3-1 Alarm list" for details.)
CAUTION
This drop prevention function does not prevent the axis from dropping under all
conditions. To prevent the axis from dropping under all conditions, take measures
on the machine such as installing a balance unit.
(2) Function outline and parameter settings
While stopped ....... The drive unit enters the ready OFF state after the vertical axis drop prevention
time (SV048) has elapsed.
While moving......... Deceleration stop is carried out, and the drive unit enters the ready OFF state
after the larger value of the vertical axis drop prevention time (SV048) and
emergency stop maximum delay time (SV055) has elapsed.
Emergency
stop
Brake
operation
Servo ON
Tbd
EMGrt
Tbd: Brake operation delay time
Drop prevention function sequence during emergency stop
EMGrt > Tbd
Detect in-position
and turn servo OFF
Emergency
stop
Brake
operation
Tbd
Tbd: Brake operation delay time
Servo ON
Actual
o
p
eration
Rapid
traverse rate
Motor speed
EMGx
Deceleration stop function sequence during emergency stop
0
Command
EMGt