2-4 Examining operating status
Selection guidelines
2-9
1
2
3
4
5
6
7
8
9
10
11
Apx
Sel
ect
ion gui
del
ines
Acceleration time and deceleration time
Calculate acceleration and deceleration times for the selected actuator.
Acceleration time:
Deceleration time:
T
a
: Acceleration time
(s)
T
d
: Deceleration time
(s)
J
A
: Actuator inertia moment
(kg·m
2
)
J
L
: Load inertia moment
(kg·m
2
)
N: Actuator rotation speed
(r/min)
T
M
: Maximum actuator torque
(N·m)
T
F
: Actuator friction torque
(N·m)
T
F
= K
T
x I
M
– T
M
K
T
: Torque constant
(N·m/A)
I
M
: Max. current
(A)
T
L
: Load torque (N·m): The polarity is positive (+) when the torque is applied in the rotation direction, or
negative (-) when it is applied in the opposite direction.
Example 1
Select an actuator that best suits the following operating conditions:
• Rotation speed: 100 r/min
• Load inertia moment: 0.04 kg·m
2
• Since the load mechanism is mainly inertia, the load torque is negligibly small.
1
After applying these conditions to the graph in [2-1], FHA-11C-50 is tentatively selected.
2
From the rated table in [1-4], the following values are obtained: J
A
= 0.017 kg·m
2
,
T
M
= 8.3 N·m. K
T
= 6.6 N·m/A, I
M
= 1.6A.
3
Based on the above formula, the actuator's friction torque TF is calculated as 6.6 x
1.6 - 8.3 = 2.3 N·m.
4
Therefore, the acceleration time and deceleration time can be obtained as follows
from the above formulas:
t
a
= (0.017 + 0.04) x 2 x
π
/ 60 x 100 / 8.3 = 0.072 s
t
d
= (0.017 + 0.04) x 2 x
π
/ 60 x 100 / (8.3 + 2 x 2.3) = 0.046 s
5
If the calculated acceleration/deceleration times are too long, correct the situation by:
• Reducing moment of inertia of load
• Selecting an actuator with a larger frame size
ta
td
N
Time
Rotation speed
(
)
L
M
L
A
a
T
T
N
60
2
J
J
t
−
×
π
×
×
+
=
(
)
L
F
M
L
A
d
T
T
2
T
N
60
2
J
J
t
+
×
+
×
π
×
×
+
=