Coupling With The Load - Mitsubishi Electric MDS-E Series Instruction Manual

MDS-E/EH Series Instruction Manual
1 Installation

1.1.7 Coupling with the Load

There are several ways to couple the motor shaft and machine, such as direct coupling with flexible coupling or rigid
coupling, gear connection, timing belt connection, etc.
Summarized comparison is as follows.
No
Noise lubric
ation
Direct coupling
with
◯ ◯
flexible coupling
Direct coupling
with
◯ ◯
rigid coupling
Gear × ×
Timing belt
△ ◯
CAUTION
If the cautions in motor installation in the above table are not observed, the motor will have a broken shaft, or the bearing
will have a shorter life. Carry out design and installation adjustment so that the load on the motor shaft will be below the
tolerable loads mentioned in "Shaft Characteristics".
(1) Direct coupling - Flexible coupling
When coupling the load directly, a flexible coupling is recommended. The benefits of a flexible coupling are as
below.
(a) Shaft's angle deviation and core deviation can be absorbed to some extent, so adjustment in motor installation
is easier.
However, in the case of single, shaft core deviation cannot be allowed, so it is required to design and adjust so
that the shaft cores of the motor and ball screw align. Check the specification of the coupling to use. If the shaft
core deviation exceeds the coupling's tolerable level, the motor will have a broken shaft, or the bearing will
have a shorter life. Thus, in order to simplify the installation adjustment, use a double flexible coupling.
(b) Less looseness produces less vibration and less noise at the coupling part.
On the other hand, if assembling is loose, lower rigidity may be caused. When using a coupling with lower
rigidity, the accuracy in centering the core doesn't have to be high, however, it is undesirable for servo. In order
to fully utilize the servo's efficiency to ensure the maximum durability of the equipments, it is required to use a
highly rigid coupling, and to fully align the shaft cores in the initial installation. It is also required to select the
optimum flexible coupling according to the working conditions, and use it correctly according to the
manufacturer's specification manual.
Load shaft
Backl Reliability
Rigidity
ash in coupling
◯
◯ ◯
Looseness of bolt
◯
◯ ◯
Looseness of bolt
△
△ △
Tooth chipping
×
×
◯
Belt is broken
Example of direct coupling with load
Load shaft
Motor shaft
Spun ring
Flexible coupling
(a) Taper shaft
Degree of
Torque
freedom in
Life increased at
deceleration
installation
×
◯
×
◯
△ ◯
×
◯
Flexible coupling
Spun ring
(b) Straight shaft
7
Cautions in motor
motor installation
Shaft core deviation
△
(In the case of single)
Shaft core deviation
×
Angle deviation
Backlash too small
◯
Pitch diameter too small
Belt stretched too much
◯
Pitch diameter too small
Motor shaft
IB-1501229-F