Harmonic Drive RSF supermini Series, Руководство пользователя

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Chapter 2 Selection of the RSF supermini Series
- - 22
K
La
x t
a
+ K
Lr
x t
r
K
Ld
x t
d
t
•
Example: 1
The load conditions are:
•
Rotary speed: 140r/min
•
Load moment of inertia: 0.9
!
10
-3
kg m
2
•
Load torque is so small as to be negrected.
•
Acceleration/deceleration time is 0.03sec (30msec) or less.
(1) Compare these conditions with the “1-4 Specifications of RSF supermini actuators” and
temporarily select RSF-5B-50.
(2) Obtain J
A
=1.83
!
10
-4
kg•m
2
, T
M
=0.9 Nm, K
T
=0.54 Nm/A, and I
M
=2.2A from “1-4 Specifications of
RSF supermini actuators.”
(3) The friction torque of the actuator is T
F
= 0.54
!
2.2-0.9 = 0.29 Nm from Formula (3) on the previous
page.
(4) Therefore, the shortest acceleration time and deceleration time can be obtained from Formula (1)
and Formula (2), as follows:
t
a
= (0.183
!
10
-3
+0.9
!
10
-3
)
!
2
!"
/60
!
140/0.9 = 0.018 sec (18msec)
t
d
= (0.183
!
10
-3
+0.9
!
10
-3
)
!
2
!"
/60
!
140/(0.9+2
!
0.29) = 0.011 s (11msec)
(5) Because the assumed acceleration/deceleration time is 0.03sec (30msec) or less, the temporarily
selected actuator can be used for acceleration/deceleration, based on the result of (4).
(6) If the calculation results of the acceleration/deceleration time do not fall within the desired time
range, examine them again as follows.
•
Try to reduce the load moment of inertia.
•
Re-examine the gear ratio and gear head model.
2-4-5 Calculating equivalent duty
The load conditions, which are torque, speed,
moment of inertia, acceleration/deceleration time,
loading time, are limited by the actuator to drive the
load. To select the proper actuator, the equivalent
duty of the load should be calculated.
The %ED (percent equivalent duty) is:
%ED = x100 (4)
where, ta: acceleration time in second
td: deceleration time in second
tr: driving time in second
t: single cycle time in second
K
La
: duty factor for acceleration time
K
Lr
: duty factor for driving time
K
Ld
: duty factor for deceleration time
Ta, Tr, Td: output torque
ta
td
N
tr
Time
Speed
t: duty cycle
ts
Tr
T
a
Time
Tor
que
Td
D
o
n
o
t
p
l
u
g
t
h
e
a
c
ts: stop time