
3.INSTRUCTIONS DESCRIPTIONS FOR FANUC AC SERVO MOTOR β series B-65232EN/03
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3.1 DRIVE SHAFT COUPLING
There are four methods for connecting the motor shaft to the ball
screw:
• Direct connection through a flexible coupling
• Direct connection through a rigid coupling
• Connection through gears
• Connection through timing belts
It is important to understand the advantages and disadvantages of each
method,
and select one that is most suitable for the machine.
(1) Direct connection using a flexible coupling
Direct connection by a flexible coupling has the following
advantages over connection using gears:
• A certain misalignment of the angle between the motor
shaft and the ball screw can be compensated.
• Because a flexible coupling connects elements with less
backlash, driving noise from joints can be significantly
suppressed.
However, this method has the following disadvantages:
• The misalignment of the center between the motor shaft and
the ball screw is not permitted (in the case of single
coupling).
• Loose assembly may result in lower rigidity.
When the motor shaft needs to be connected directly to the ball
screw, connecting them using a flexible coupling facilitates
adjustment and installation of the motor.
To use a single coupling, the machine needs to be designed so
that the centers of the motor shaft and the ball screw are aligned.
If it is difficult to align the centers, a double coupling needs to be
employed.
Flexible
Motor shaft
Ball screw
Locking
Flexible
Motor shaft
Ball screw
Locking