Chapter 2 Selection of the RSF supermini Series
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23
•
Example 2: getting duty factors of K
La
, K
Lr
and K
Ld
As a result of Calculation Example 1 shown below, the selected actuator RSF-5B-50 works fine, so
RSF-5B-50 can be used for duty factor graphs.
Operation conditions:
•
The inertial load is accelecated at the maximum torque of the actuator, and decelerated at the
maximum torque after operation at a fixed speed.
•
The movement angle
#
of one cycle is 120
°
.
•
The duration of one cycle is 0.4 (s).
•
The other conditions are the same as Calculation Example 1.
(1) K
La
and K
Ld
: The average speed during the rotation speed change from 0 to 140r/min is 70r/min.
From the duty factor graphs, K
La
=K
Ld
1.5 can be obtained.
(2) K
Lr
: Tr
0 for the inertial load. Similarly, from the duty factor graphs, K
Lr
0.29 can be read.
(3) The movement angle can be obtained from the area in the “Rotation speed-Time” diagram above.
In other words, the movement angle
#
can be expressed as follows:
#
= (N / 60) x {tr + (ta + td) / 2} x 360
Solving the formula above for tr (operation time at a fixed speed of N), the following can be
obtained.
tr =
#
/ (6 x N) – (ta + td) / 2
Substituting
#
= 120° and ta=0.03(s), td=0.03(s), and N= 140r/min from Example 1, tr=0.113(s).
(4) Because the cycle time is 0.4(s), the %ED is obtained as follows:
%ED = (1.5x 0.03 + 0.29 x 0.113 + 1.5 x 0.03) / 0.4 x 100 = 30.7%
Because the value of %ED obtained is below 100, continuous repeated operation of this cycle can
be done.
If the %ED is exceeded 100%, correct the situation by:
•
Changing the speed-time profile
•
Reducing load moment of inertia
70
140
RSF-5B-50-US050-C
Radiation plate: 150
!
150
!
3[mm]
Allowed range
KL=0.33
0.67
1
1.5
(2) K
Lr
Estimation line for
KL=0.29
(1) K
La,
K
Ld
Tor
que
[N
m
]
Speed [r/min]
