2-4 Examining operating status
Selection guidelines
2-13
1
2
3
4
5
6
7
8
9
10
11
Apx
Sel
ect
ion gui
del
ines
Examining effective torque and average rotation speed
Consider the following two points when obtaining the effective torque and average rotational speed.
The effective torque should be less than the allowable continuous torque.
The average rotational speed should be less than the allowable continuous rotational speed.
Using the following formula, calculate the effective torque T
m
and average rotation speed N
av
when
the operating cycle shown in [Duty cycles] (P2-10) is operated repeatedly.
T
m
: Effective torque (N·m)
T
a
: Maximum torque (N·m)
T
r
: Load torque (N·m)
t
a
: Acceleration time (s), td: deceleration time (s)
t
r
: Operation time at constant speed (s), t: time for 1 duty cycle (s)
N
av
: Average rotation speed (r/min)
N: Rotation speed at constant speed (r/min)
If the effective torque is greater than the allowable continuous torque in the table below, calculate once
again after reducing the duty cycle.
Model
Item
FHA-8C
FHA-11C
FHA-14C
-30
-50
-100
-30
-50
-100
-30
-50
-100
Reduction ratio
1:30
1:50
1:100
1:30
1:50
1:100
1:30
1:50
1:100
Allowable continuous
torque
N·m
0.75
1.5
2
1.8
2.9
4.2
3.5
4.7
6.8
Allowable continuous
rotational speed
r/min
117
70
35
117
70
35
100
60
30
Example 3: Examining effective torque and average rotation speed
Use the operating conditions found in example 1 and 2 to get the effective torque and average rotation speed.
Substituting 8.3 N·m for T
a
, 8.3 N·m for T
d
, 0 N·m for T
r
, 0.072 s for t
a
, 0.14 s for t
r
, 0.046 s for t
d
, and
0.8 s for t:
1) Examining effective torque
As T
m
exceeds its allowable continuous torque of the FHA-11C-50 temporarily selected in example 1,
it is impossible to drive the actuator continuously with the duty cycle in example 2. The following
formula is a modified version of the formula for effective torque. By applying the value of allowable
continuous torque to T
m
in this formula, the allowable cycle time can be calculated.
Substituting 8.3 N·m for T
a
, 8.3 N·m for T
d
, 0 N·m for T
r
, 3.03 N·m for T
m
, 0.072 s for t
a
, 0.14 s for t
r
,
and 0.046 s for t
d
: Then, the following equation is obtained:
Setting the cycle time to 0.97 seconds or more gives T
m
= 2.9 N·m or less, thereby permitting
continuous operation within the allowable continuous torque.
Calculate the average speed by substituting in parameters N = 100 r/min, t
a
= 0.072 s, t
r
= 0.14 s,
t
d
= 0.046 s and t = 0.97 s.
2) Examining average rotation speed
As the average speed is less than the allowable continuous rotation speed (70 r/min) of FHA-11C-50,
it can be driven continuously.
(
)
t
t
T
t
t
T
T
r
2
r
d
a
2
a
m
×
+
+
×
=
t
t
2
N
t
N
t
2
N
N
d
r
a
av
×
+
×
+
×
=
(
)
3.19 N·m
0.046
=
+
×
=
0.8
0.072
8.3
T
m
2
(
)
2
m
r
2
r
d
a
2
a
T
t
T
t
t
T
t
×
+
+
×
=
min
/
r
5
.
20
0.97
046
.
0
2
/
100
14
.
0
100
072
.
0
2
100
N
av
=
×
+
×
+
×
=
(
)
97
.
0
9
.
2
046
.
0
072
.
0
3
.
8
t
2
2
=
+
×
=
