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Design Check Items
SFS MODEL
¢
Operating limit rotation speed
For the SFS-G long spacer type, the rotation speed at which it
can be operated differs according to the spacer length selected.
Check the table below and make sure that the rotation speed
to be used is lower than or equal to the operating limit rotation
speed.
If the maximum rotation speed is specified by type, this specified
rotation speed will be used as the upper limit.
200
300
400
500
600
700
800
900
1000
2000
10000
9000
8000
7000
6000
5000
4000
3000
200
500
1000
2000
3000
20000
30000
Floating length [mm]
SFS-10G
SFS-12G
SFS-14G
SFS-09G
SFS-08G
SFS-06G
SFS-05G
Operating limit rotation speed [min
–1
]
Load character
Constant
Fluctuations: Slight
Fluctuations: Medium
Fluctuations: Large
1.0
1.25
1.75
2.25
¢
Selection procedure
(1) Calculate torque Ta applied to the coupling based on the
motor output P and coupling operating rotation speed n.
In servo motor drive, multiply the service factor K=1.2 to 1.5 by
the maximum torque of servo motor Ts.
¢
Feed-screw systems
ò
Oscillation phenomena of servo motors
If the eigenfrequency of the entire feed-screw system is under
400 to 500Hz, oscillation may occur depending on the gain
adjustment of the servo motor. An oscillation phenomenon
of a servo motor occurs mainly by the problem of the
eigenfrequency of the entire feed-screw system and the
electric control system.
These problems can be avoided by raising the eigenfrequency
of the mechanical system from the design phase or adjusting
the tuning function (filter function) of the servo motor.
(2) Calculate corrected torque Td applied to the coupling after
deciding the service factor K based on load conditions.
(3) Select the size in order that the coupling permissible torque
Tn becomes equal or greater than the corrected torque Td.
(4) Depending on the bore diameters, the coupling permissible
torque may be limited. Refer to the “Specification” and
“Standard bore diameter.”
(5) Confirm if the required shaft diameter does not exceed the
maximum bore diameter of the coupling.
For machines whose load torques periodically fluctuate
drastically, contact us.
ò
Resonance caused by stepping motors
It is a phenomenon that occurs within a certain rotation speed
range by the pulsation frequency of the stepping motor and
the eigenfrequency of the entire system. Resonance can be
avoided by not applying the resonant rotation speed, or by
reviewing the eigenfrequency in the design phase.
Contact us for unclear points concerning ocsillation phenomena
of servo motors and resonance of stepping motors.
Td = Ta × K (see below)
Ta [N·m] = 9550 ×
P [kW]
n [min
−1
]
Td = Ts × (1.2 to 1.5)
Tn
≥
Td
Motor
Feed
screw
Bearing
Table
Coupling
¢
How to evaluate the eigenfrequency of
feed-screw system
(1) Select the coupling according to the normal operating torque
and maximum torque of the servo motor/stepping motor. (Refer
to the selection procedure on the left.)
Nf: Eigenfrequency of the entire feed-screw system [Hz]
k
: Torsional stiffness of the coupling and feed screw [N·m/rad]
J1: Moment of inertia of the driving side [kg·m
2
]
J2: Moment of inertia of the driven side [kg·m
2
]
(2) In the following feed-screw system, evaluate the entire
eigenfrequency: Nf from the torsional stiffness: K of the
coupling and feed screw, the moment of inertia: J1 of the
driving side and the moment of inertia: J2 of the driven side.
J1
J2
Содержание COUPLINGS
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