Chapter 2 Selection of the RSF supermini Series
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20
2-4 Duty cycles
When a duty cycle includes many frequent start and stop operations, the actuator generates heat by
big 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 RSF supermini
actuator speed (r/min) to drive the load.
Rotary speed (r/min) =
Liner speed (mm/min)
Pitch of screw(mm)
For linear motion, convert with the formula
below:
Select a reduction ratio from [30], [50] and
[100] of an RSF supermini actuator of which
the maximum speed is more than the
required speed.
2-4-2 Load moment of inertia
Calculate the load moment of inertia driven by the RSF supermini series actuator.
Refer to appendix 1 for the calculation.
Tentatively select an RSF supermini actuator referring to section [2-1 allowable load moment of 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.
µ
T: torque (Nm)
µ: coefficient of friction
W: mass
(kg)
r: radius of friction face (m)
The load torque is restricted by the allowable load of the actuator (refer to “1-10 Allowable load”) and
load moment of inertia as well as by the load driven by the actuator.
Examine them carefully before using the actuator.
Speed (r/min)
45r/min
90r/min
100r/min
333r/min
200r/min
150r/min
Linear speed (mm/min)
Screw pitch (mm)
Radius
: r
Mass: W
Friction:µ
