2.1 Selecting the Servomotor Capacity
2.1.2 Capacity Selection Example for a Rotary Servomotor: For Position Control
2
Capacity
S
election
2-5
3.
Motor Speed
4.
Load Torque
5.
Load Moment of Inertia
6.
Load Moving Power
7.
Load Acceleration Power
8.
Servomotor Provisional Selection
Selection Conditions
•
T
L
≤
Motor rated torque
•
•
n
M
≤
Rated motor speed
•
J
L
≤
Allowable load moment of inertia
The following Servomotor meets the selection conditions.
•
SGM7J-01A Servomotor
Specifications of the Provisionally Selected Servomotor
•
Load shaft
speed
•
Motor shaft
speed
Direct coupling gear ratio 1/R = 1/1
Therefore,
n
M
=
n
L
⋅
R = 3,000
×
1 = 3,000 (min
-1
)
•
Linear motion section
•
Ball screw
•
Coupling
•
Load moment of inertia at motor shaft
J
L
=
J
L1
+
J
B
+
Jc =
1.25
×
10
-4
(kg
m
2
)
Item
Value
Rated Output
100 (W)
Rated Motor Speed
3,000 (min
-1
)
Rated Torque
0.318 (N
m)
Instantaneous Maximum Torque
1.11 (N
m)
Motor Moment of Inertia
0.0659
×
10
-4
(kg
m
2
)
Allowable Load Moment of Inertia
0.0659
×
10
-4
×
35 = 2.31
×
10
-4
(kg
m
2
)
Encoder Resolution
16,777,216 (pulses/rev) (24 bits)
nL
= = =
3
,000 (min
-1
)
PB
15
0.005
υ
L
TL
=
=
= 0.1
3
9 (N
m)
2
π
R
(9.8
m
+
F
)
PB
2
π ×
1
×
0.9
(9.8
×
0.2
×
80 + 0)
×
0.005
μ
η
JL1
=
m
= 80
×
= 0.507
×
10
-4
(kg
m
2
)
2
2
π
R
PB
2
2
π ×
1
0.005
JB
=
B
dB
4
=
×
7.87
×
10
3
×
0.8
×
(0.016)
4
= 0.405
×
10
-4
(kg
m
2
)
3
2
π
3
2
π
ρ
Jc
=
mC
dC
2
=
×
0.
3
×
(0.0
3
)
2
= 0.
33
8
×
10
-4
(kg
m
2
)
8
1
8
1
PO
=
= = 4
3
.7 (W)
60
2
π
nM
TL
60
2
π ×
3
,000
×
0.1
3
9
Pa
=
=
×
×
= 12
3
.4 (W)
nM
2
60
2
π
ta
JL
3
,000
2
60
2
π
0.1
1.25
×
10
-4
< Provi
s
ionally
s
elected
S
ervomotor rated output < (
Po
+
Pa
)
2
(
Po
+
Pa
)
