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Appendix 2. Selection
A2 - 15
Appendix 2-4 Motor shaft conversion load torque
The calculation method for a representative load torque is shown.
Type Mechanism Calculation expression
Linear
movement
W
Z
1
Z2
FC
F0
Servomotor
T
L =
F in the above expression is obtained from the expression below
when the table is moved as shown on the left.
F = Fc +
(W
.
g +
F0)
F
.
∆S
2×10
3
V
N
)
=
F
2×10
3
·
(
Fc : Force applied on axial direction of moving section (N)
F
0 : Tightening force on inner surface of table guide (N)
W : Total mass of moving section (kg)
g : Gravitational acceleration = 9.8 (m/s
2
)
: Friction coefficient
TL : Load torque (N
.
m)
F : Force in axial direction of the machine
that moves linearly (N)
: Drive system efficiency
V : Speed of object that moves linearly (mm/min)
N : Motor speed (r/min)
∆S : Object movement amount per motor
rotation (mm)
Z1, Z2 : Deceleration ratio
Servomotor
T
LO
Z1 Z2
T
L = · · TLO + TF = · · TLO + TF
Rotary
movement
W2
W1
1/n
Servomotor
Guide
Counter-
weight
Load
When rising
TL = TU + TF
When lowering
T
L = –TU ·
2
+ TF
T
U = · ( ) =
T
F =
Vertical
movement
V
N
(W
1
W
2
) · g
2
10
3
(W
1
– W
2
) · g · ∆S
2
10
3
· (W
1
+ W
2
) · g · ∆S
2
10
3
1
T
L : Load torque (N
.
m)
T
LO : Load torque on load shaft (N
.
m)
T
F : Motor shaft conversion load friction torque (N
.
m)
: Drive system efficiency
Z
1
, Z
2
: Deceleration ratio
n : Deceleration rate
TL : Load torque (N
.
m)
T
U : Unbalanced torque (N
.
m)
T
F : Friction torque on moving section (N
.
m)
Z
1
Z
2
W
1
: Load mass (kg)
W
2
: Counterweight mass (kg)
: Drive system efficiency
g : Gravitational acceleration = 9.8 (m/s
2
)
V : Speed of object that moves linearly (mm/min)
N : Motor speed (r/min)
∆S : Object movement amount per motor rotation (mm)
: Friction coefficient
1
1
n