
4.SELECTING A MOTOR DESCRIPTIONS FOR FANUC AC SERVO MOTOR β series B-65232EN/03
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(3) Mechanical specifications
Data in this blank serve as the basis for selecting the motor.
Enter these data correctly.
(a) Travelling distance of machine per revolution of the motor
Enter the travelling of the machine when the motor rotates
one turn.
Example 1)
When the pitch of ball screw is 12 mm and the gear
ratio is 2/3,
12(mm)×2/3=8(mm)
Example 2)
When the gear ratio is 1/72 in rotary table ;
360(deg) ×1/72=5(deg)
(b) Total gear ratio
Enter the gear ratio between the ball screw and the servo
motor, gear ratio between the final stage pinion and the
servo motor in case of the rack pinion drive, or gear ratio
between the table and the motor in case of rotary table.
(c) Inertia
Enter a load inertia value reflected to the motor shaft.
It is not always necessary to enter this inertia value in detail.
Enter it as a 2-digit value.
Example) 0.2865 → 0.29
Do not include any inertia of the motor proper in this value.
(d) Least input increment of CNC
Enter the least input increment of CNC command.
(e) Maximum rapid traverse feedrate
Enter a maximum rapid traverse feedrate according to the
mechanical specifications.
(f) Motor speed in rapid traverse
The motor speed in the maximum rapid traverse feedrate is
entered.
(g) Acceleration/deceleration time in rapid traverse
The acceleration/deceleration time is determined according
to the load inertia, load torque, motor output torque, and
working speed.
The acceleration/deceleration mode at rapid traverse is
generally linear acceleration/deceleration in FANUC's
CNC.
Speed
Vm
ta
ta
Time
(h) Distance of positioning in rapid traverse
Enter the amount of travel when positioning during rapid
traverse.