
4.ADJUSTMENT FANUC AC SPINDLE MOTOR αi series B-65280EN/05
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4.1.3 Adjustment Procedure
(1) Start of each operation mode
In preparation for the adjustment, settings must be made so that a
stable operation takes place in each mode without overshoot or
oscillation.
See Chapter 2, "EXPLANATION OF OPERATION MODES",
temporarily set parameters (acceleration/deceleration time constant,
position gain, and so on) to make operations stable in each operation
mode, and confirm operations.
NOTE
When a motor with a large torque-to-inertia ratio (for
example, low-speed winding of a motor with an
speed range switching function) is used, or when the
rigidity of the spindle is low, the standard setting of
the velocity loop gain may be so high that oscillation
can occur. In such a case, decrease the velocity loop
gain.
(2) Adjustment
When adjusting the velocity loop gain, check the operation mode and
clutch/gear signal, and modify corresponding parameters. Follow the
steps below to adjust the parameters:
<1> Determining the oscillation limit
Basically, determine the oscillation limit based on torque
commands, position errors, vibration, sound, and so on when the
motor is stopped (for orientation, after completion of the
operation) or when the motor rotates at a certain speed not higher
than the base speed. Normally, increase the proportional gain and
integral gain settings in steps of about 5; for a motor with a large
torque-to-inertia ratio, increase these settings in steps of about 2.
As the settings are increased gradually, the symptoms below start
to appear at a certain setting level. The settings at this level are
determined to be the oscillation limit:
- The machine vibrates or produces large sound.
- Vibration of a torque command becomes large.
- Position errors at stop time vary largely.
NOTE
The oscillation limit varies with the spindle inertia. In
a machine in which the inertia varies largely
according to the tool and workpiece used,
adjustment must be made in the smallest inertia
state.