11.1 Servomotor Capacity Selection Examples
11-5
(4) Load Moment of Inertia
• Liner motion section
• Ball screw
• Coupling
• Load moment of inertia at the motor shaft
(5) Load Moving Power
(6) Load Acceleration Power
(7) Provisionally Servomotor Selection
(a) Selecting Conditions
• T
L
≤ Motor rated torque
• Pa + Po = (1 to 2) × Motor rated output
• N
M
≤ Motor rated speed
• J
L
≤ SERVOPACK allowable load moment of inertia
The followings satisfy the conditions.
• SGMPH-02AAA21 servomotor
• SGDH-02AE SERVOPACK
(b) Specifications of Servomotor and SERVOPACK
• Rated output: 200 (W)
• Rated motor speed: 3000 (min
-1
)
• Rated torque: 0.637 (N⋅m)
• Instantaneous peak torque: 1.91 (N⋅m)
• Servomotor rotor moment of inertia: 0.209 × 10
-4
(kg⋅m
2
)
• SERVOPACK allowable load moment of inertia: 3.69 × 10
-4
(kg⋅m
2
)
• Number of encoder pulses: 2048 (P/R)
J
L1
= M
(
)
2
= 80 ×
(
)
2
= 0.507 × 10
-4
(kg
m )
P
B
2πR
0.005
2π × 1
2
J
B
= ρ
L
B
D
B
4
= × 7.87 × 10
3
× 0.8 × (0.016)
4
= 0.405 × 10
-4
(kg
m
2
)
π
32
π
32
J
C
= M
C
D
C
4
= × 0.3 × (0.03)
2
= 0.338 × 10
-4
(kg m
2
)
8
1
1
8
J
L
= J
L1
J
B
J
C
= 1.25 × 10
-4
(kg m
2
)
P
O
= = = 43.7 (W)
2πN
M
T
L
60
2π × 3000 × 0.139
60
P
a
=
(
N
M
)
2
=
(
× 3000
)
2
-4
= 123.4 (W)
2π
60
2π
60
J
L
ta
1.25 × 10
0.1
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