
5.FUNCTION DESCRIPTIONS FANUC AC SPINDLE MOTOR αi series B-65280EN/05
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5.7.6 Parameter Tuning Procedure
(1) Parameter initialization
Initialize the parameters related to the unexpected disturbance torque
detection function as listed below.
No. Description Initial setting
4015#1
Whether the unexpected disturbance torque
detection function is available (The CNC software
option is required.)
1
4248 Torque constant for spindle load torque monitoring
Specify an appropriate value according to the
spindle inertia (see the following expression).
4249 Observer gain 1 for spindle load torque monitoring 500
4250 Observer gain 2 for spindle load torque monitoring 500
4341 Unexpected disturbance torque detection level
0 (to be changed to an appropriate value
according to the use of the machine)
(2) Initial setting of the torque constant (parameter No. 4248)
Using the following expression, calculate the initial torque constant
setting according to the spindle inertia and specify it in the
corresponding parameter.
889.4
max
×
+
=
JlJm
T
Kt
T
max : Motor maximum output torque [Nm] (Use 120% of the
30-minute rated torque as a rough standard.)
Jm : Motor rotor inertia [kgm
2
]
Jl : Spindle inertia (in terms of motor axis inertia) [kgm
2
]
Example)
Initial torque constant setting for the α3/10000
i
Letting motor rotor inertia Jm, motor maximum output torque
Tmax, and spindle inertia Jl be, respectively, 0.0148 kgm
2
, 35.0
× 1.2 = 42.0 Nm, and 0.0250 kgm
2
, the torque constant is:
Kt = 42.0/(0.0148 + 0.0250) × 4.889 = 5159.24
So, set parameter No. 4248 to "5159".