
4. SELECTING A MOTOR
B–65142E/04
DESCRIPTIONS FOR THE α series
48
Enter the name of the separate type pulse coder, if used.
The acceleration/deceleration time is determined according to the load
inertia, load torque, motor output torque, and working speed. For details
of calculations, refer to Subsec. 4.1.2 and 4.1.3.
The acceleration/deceleration mode at rapid traverse is generally linear
acceleration/deceleration in FANUC’s CNC.
Speed
Vm
ta ta
Time
The acceleration/deceleration at cutting feed is exponential acceleration
/deceleration in general. This blank is filled in with its time constant
Vm
0.632Vm
te te
Speed
te : Time constant
Time
Enter whether or not feed–forward control is used.
Generally, feed–forward control can reduce the delay time in executing
servo commands. However, overheating of the motor is more likely to
occur as a higher torque is required for acceleration/deceleration. Since
mechanical shock increases by only the No.1 time constant, generally also
set the No.2 acceleration/deceleration time constant or FAD time constant
when using feed–forward control.
Fill in this blank with a value which is considered to be settable judging
it from the inertia value based on experiences.
Since this value is not always applicable due to rigidity, damping
constant, and other factors of the machine tool, it is usually determined
on the actual machine tool. If the position detector is mounted outside the
motor, this value is affected by the machine tool rigidity, backlash
amount, and friction torque value. Enter these values without fail.
D Separate type pulse
coder
D Acceleration /
deceleration time
constant at rapid
traverse
D Acceleration/
deceleration time
constant at cutting feed
D Feed–forward during
rapid traverse
D Position loop gain