Harmonic Drive FHA Mini Series, Manual

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Chapter 2 Guidelines for sizing
FHA-mini
29
2-4 Duty cycles
When a duty cycle includes many frequent start and stop operations, the actuator generates heat by
high starting and braking current. Therefore, it is necessary to study the duty cycle profile.
The study is as follows:
2-4-1 Actuator speed
Calculate the required actuator speed (r/min) to
drive the load.
For linear motion, convert with the formula below:
Select a reduction ratio from [30], [50] and [100] of
an actuator of which the maximum speed is more
than the required speed.
2-4-2 Load inertia
Calculate the load inertia driven by the FHA-C mini series actuator.
Refer to appendix 1 for the calculation.
Tentatively select an FHA-C mini actuator referring to section [2-1 allowable load inertia] with the
calculated value.
2-4-3 Load torque
Calculate the load torque as follows:
• Rotary motion
The torque for the rotating mass [W] on the
friction ring of radius [r] as shown in the
figure to the right.
T : torque (N•m)

: coefficient of friction
W: mass (kg)
r : radius of friction face (m)
In the right graph, the oblique solid lines
for torque have been calculated with the
coefficient of the friction of

=0.1.
The oblique dot-chain lines show 20%
torque of actuators converted from 300%
torque corresponding to its maximum
torque.
100 1000 3000 30 300
1
10
30
3
100r/min
70r/min
50r/min
35r/min
Linear speed (mm/min)
Screw pitch (mm)
Speed (r/min)
200r/min
1 10 30 0.3 3
10
100
300
30
Mass W (kg)
R
a
d
iu
s
o
f
fr
ict
io
n
f
a
ce
r
(
m
m
)
0.1 N • m
Example. torque calculation (friction=0.1)
FHA(ratio:1/50): 20% torque of maximum torque
0.7 N • m
1 N • m
10 N • m
2 N • m
5 N • m
3 N
･
m
0.5 N • m
0.3 N • m
0.2 N
•
m
FHA-8C-30
FHA-8C-50
FHA-8C-100
FHA-11C-30
FHA-11C-50
FHA-11C-100
FHA-14C-30
FHA-14C-50
FHA-14C-100
Radius
: r
Mass: W
Friction: μ