2-4 Examining operating status
Selection guidelines
2-9
1
2
3
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7
8
9
10
11
Apx
Se
lec
tion gui
de
lin
es
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)
According to the conditions above, tentatively select FHA-11C-50 from the table in section 2-1.
(2)
From the rating table in section 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
= 1.6 [A]
(3)
Based on the above formula, the actuator's friction torque T
F
is calculated as
6.6 × 1.6 - 8.3 = 2.26 [N·m].
(4)
The acceleration time and deceleration time can be obtained as follows from the above
formulas:
t
a
= (0.017 + 0.04) × 2 ×
π
/ 60 × 100 / 8.3
≒
0.072 [s]
t
d
= (0.017 + 0.04) × 2 ×
π
/ 60 × 100 / (8.3 + 2 × 2.26)
≒
0.047 [s]
(5)
If the calculated acceleration/deceleration times are too long, correct the situation by:
･
Reducing the inertia moment of load
･
Selecting a 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
×
×
+
=
