SMC Networks LEFS Series Manual page 2

Electric Actuator/Slider Type
Ball Screw Drive/
Model Selection
Selection Procedure
Step 1
Check the work load–speed.
Selection Example
Operating
¡ Workpiece mass: 5 [kg]
conditions
¡ Speed: 300 [mm/s]
¡ Acceleration/Deceleration: 3000 [mm/s
¡ Stroke: 200 [mm]
¡ Mounting orientation: Horizontal upward
Step 1 Check the work load–speed. <Speed–Work load graph>
Select the target model based on the workpiece mass and speed with
reference to the <Speed–Work load graph>.
Selection example) The LEFS25RA-200 is temporarily selected based on the
graph shown on the right side.
Step 2 Check the cycle time.
Calculate the cycle time using the following
calculation method.
Cycle time :
T can be found from the following equation.
T = T1 + T2 + T3 + T4 [s]
¡ T1: Acceleration time and T3: Deceleration
time can be obtained by the following equation.
T1 = V/a1 [s]
¡T2: Constant speed time can be
found from the following equation.
L − 0.5·V·(T1 + T3)
T2 =
V
¡T4: Settling time varies depending
on the conditions such as motor
types, load and in positioning of
the step data. Therefore, please
calculate the settling time with
reference to the following value.
T4 = 0.2 [s]
Step 3 Check the guide moment.
Mep
m
L1
Based on the above calculation result,
the LEFS25RA-200 is selected.
∗ If the step motor and servo motors do not meet your specifications, please also consider the AC servo specifications (Page 16).
1
Series
Step 2 Check the cycle time.
¡Workpiece mounting condition:
W
]
2
Calculation example)
T1 to T4 can be calculated as follows.
T1 = V/a1 = 300/3000 = 0.1 [s],
T3 = V/a2 = 300/3000 = 0.1 [s]
T2 =
T3 = V/a2 [s]
=
= 0.57 [s]
T4 = 0.2 [s]
[s]
Therefore, the cycle time can be
obtained as follows.
T = T1 + T2 + T3 + T4
= 0.1 + 0.57 + 0.1 + 0.2
= 0.97 [s]
Step Motor
(Servo/24 VDC)
LEFS
(Pages 2 and 3)
L − 0.5·V·(T1 + T3)
V
200 − 0.5·300·(0.1 + 0.1)
300
2,000
1,500
1000 mm/s 2
3000 mm/s
1,000 2
500
5000 mm/s
2
0
0 5 10 15 20
Work load [kg]
Servo Motor
(24 VDC)
Step 3 Check the allowable moment.
20
LEFS25B
Lead 6:
15
10
Lead 12:
5
LEFS25A
0
0 100 200 300 400 500 600 700
Speed: V [mm/s]
<Speed–Work load graph>
(LEFS25/Step motor)
L
a1
T1 T2 T3
(Operating condition)
L : Stroke [mm] ····················
················ (Operating condition)
V : Speed [mm/s]
(Operating condition)
···
a1: Acceleration [mm/s ]
2
(Operating condition)
a2: Deceleration [mm/s ] ···
2
T1: Acceleration time [s]
Time until reaching the set speed
T2: Constant speed time [s]
Time while the actuator is operating
at a constant speed
T3: Deceleration time [s]
Time from the beginning of the constant
speed operation to stop
T4: Settling time [s]
Time until in position is completed
(1 kg = 2.2 lb)
a2
Time
[s]
T4