
3.INSTRUCTIONS DESCRIPTIONS FOR FANUC AC SERVO MOTOR β series B-65232EN/03
- 22 -
(4) Timing belt
A timing belt is used in the same cases as gear connection, but in
comparison, it has advantages such as low cost and reduced
noise during operation, etc. However, it is necessary to correctly
understand the characteristics of timing belts and use them
appropriately to maintain high precision.
Generally, the rigidity of timing belt is sufficiently higher than
that of other mechanical parts such as ball screw or bearing, so
there is no danger of inferiority of performance of control caused
by reduction of rigidity by using timing belt. When using a
timing belt with a position detector on the motor shaft, there are
cases where poor precision caused by backlash of the belt tooth
and pulley tooth, or elongation of belt after a long time becomes
problem, so consideration should be given to whether these
errors significantly affect precision. In case the position detector
is mounted behind the timing belt (for example, on the ball
screw axis), a problem of precision does not occur.
Life of the timing belt largely varies according to mounting
precision and tension adjustment. Please refer to the
manufacturer's Instruction Manual for correct use.
(5) Connection between the straight shaft and a connecting element
To use a straight shaft that has no key groove, connect the shaft
with a coupling using a span ring.
Because the span ring connects elements by the friction
generated when the screw is tightened, it is free from backlash
and the concentration of stress. For this reason, the span ring is
highly reliable for connecting elements.
To assure sufficient transmission with the span ring, factors such
as the tightening torque of the screw, the size of the screw, the
number of screws, the clamping flange, and the rigidity of
connecting elements are important. Refer to the manufacturer's
specifications before using the span ring.
When a coupling or gear is mounted using the span ring, tighten
the screws to remove a run-out of the coupling or gear including
the shaft.