
B-63323EN-1/03 2.PREAPARATIONS FOR OPERATION
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2.9 ABNORMAL LOAD DETECTION
Overview
When the machine collides, or if a defective or damaged tool is used, a
load torque greater than that applied in normal feed and cutting is
applied to the servo and spindle motors. This function detects the load
torque applied to the motors, and passes the load torque as an estimated
load torque to the PMC through the CNC. Moreover, when a torque
greater than a parameter-set value is detected, this function stops the
servo and spindle motors as soon as possible or rotates the motors by an
appropriate parameter-set amount in the direction opposite to the
forward direction to minimize damage to the machine. (The function
for rotating a motor by an appropriate amount in the opposite direction
is enabled for the servo motors only.)
This function is divided into two functions, as described below.
(1) Estimated load torque output function
The CNC calculates an estimated load torque, excluding the
motor torque, required for acceleration/deceleration at all times.
When the estimated load torque output function is enabled, the
data can be read from the PMC with the window function.
(2) Abnormal load detection alarm function
If a load torque greater than the parameter-set value is detected, this
function stops the motor, or rotates the motor in the direction opposite
to the forward direction by the amount specified in the parameter, and
causes the CNC to issue an alarm. (The function for rotating the motor
in the direction opposite to the forward direction is enabled only for
servo motors.)
NOTE
The abnormal load detection function for the spindle
motor is usable with a serial spindle only. This
function is not usable with an analog spindle.