Mitsubishi Electric MELSERVO HG-MR Instruction Manual page 387

APPENDIX
(6) Load moment of inertia (converted into equivalent value on servo motor shaft)
Moving part
-3
S 10
J = W •
L1
2
Ball screw
B
J = • D
L2 B
32
3 3
ρ = 7.8 • 10 [kg/m
Gear (servo motor shaft)
G
J = • D
L3 G1
32
Gear (load shaft)
G
J = • D
L4 G2
32
Full load moment of inertia (converted into equivalent value on servo motor shaft)
J = J + J + J + J
L L1 L2 L3
(7) Temporary selection of servo motor
Selection conditions
(a) Load torque < servo motor rated torque
(b) Full load moment of inertia < J
J : Recommended load to motor inertia ratio
R
According to above conditions, HG-KR23 (rated torque: 0.64 N•m, maximum torque: 2.2 N•m,
moment of inertia: 0.221 • 10
2
-4 2
= 1.52 • 10 [kg•m ]
2
1
4 • = 0.24 • 10 -4 [kg•m
n
] (iron)
4 -4 2
= 0.03 • 10 [kg•m ]
2
1
4 -4
• = 0.08 • 10 [kg•m
n
-4 2
= 1.9 • 10 [kg•m ]
L4
• moment of inertia of the servo motor
R
-4 2
kg•m ) is selected temporarily.
2 ]
2
]
App. - 26