Mitsubishi Electronics MDS-R ユーザーズマニュアル
Appendix 2. Selection
A2 - 16
Appendix 2-5 Expressions for load inertia calculation
The calculation method for a representative load inertia is shown.
Type Mechanism
Calculation
expression
Rotary shaft
Ø
D
1.
Ø
D
2.
J
L
= . (D
1
4
-
D
2
4
) = . (D
1
2
-
D
2
2
)
··L
Cylinder
When rotary shaft and cylinder
shaft are deviated
shaft are deviated
D
Rotary shaft
R
J
L
= . (D
2
+ 8R
2
)
Column
a
a
b
b
Rotary shaft
R
J
L
= W ( + R
2
)
Object that
moves
linearly
moves
linearly
W
V
N
Servomotor
J
L
= W ( · )
2
= W ( )
2
Suspended
object
object
D
W
J
L
= W ( )
2
+ J
P
Converted
load
load
Servomotor
Load A
J
A
N
2
N
1
N
1
J
11
J
21
J
31
Load B
J
B
N
3
J
22
J
L
= J
11
+ (J
21
+ J
22
+ J
A
) ·( )
2
+ (J
31
+ J
B
) · ( )
2
W
8
J
L
: Load inertia
[kg.cm
2
]
W : Mass of cylinder
[kg]
D : Outer diameter of cylinder
[cm]
R : Distance between rotary axis and
cylinder
axis
[cm]
a
2
+ b
2
3
J
L
:
Load
inertia
[kg.cm
2
]
W
: Mass of cylinder
[kg]
a.b.R : Left diagram
[cm]
N
3
N
1
N
2
N
1
J
L
:
Load
inertia
[kg.cm
2
]
J
A
,J
B
: Inertia of load A, B
[kg.cm
2
]
J
11
~J
31
: Inertia
[kg.cm
2
]
N
1
~N
3
: Each shaft’s speed
[r/min]
J
L
:
Load
inertia
[kg.cm
2
]
W
: Mass of object that moves linearly
[kg]
N :
Motor
speed
[r/min]
V
: Speed of object that moves linearly
[mm/min]
∆S : Object movement amount per motor rotation [mm]
V
10
1
2
N
∆S
20
D
2
J
L
: Load inertia
[kg.cm
2
]
W : Object mass
[kg]
D : Diameter of pulley
[cm]
J
P
: Inertia of pulley
[kg.cm
2
]
32
W
Rotary
shaft is
cylinder
center
shaft is
cylinder
center
8
Reference data
J
L
: Load inertia
[kg.cm
2
]
Material densities
: Density of cylinder material [kg.cm
3
]
Iron
.....
7.80
10
–3
[kg/cm
3
]
L : Length of cylinder
[cm]
Aluminum
D
1
: Outer diameter of cylinder [cm]
.....
2.70
10
–3
[kg/cm
3
]
D
2
: Inner diameter of cylinder
[cm]
Copper
W : Mass of cylinder
[kg]
.....
8.96
10
–3
[kg/cm
3
]