WEIHONG WISE WSDV-6R820PSB - 3.5.2.1 Ball Screw System Motor Selection Example

Specialized Concentrated Focused
「26」Servo Motor
Ball screw diameter B
D
=0.02[m] Ball screw pitch B
P
=0.02[m]
Ball screw efficiency B
η
=0.9 Movement distance 0.3[m]
Coupling inertia J
C
=10×10
-6
[kg·m
2
](you can refer to the value listed in product catalog or use the
calculation result.)
2) Running mode
Time
Stopping time
Dec. time
Constant
speed time
Acc. Time
Cycle time
Velocity
Movement distance
(Shallow represents distance that
has been finished.)
Fig. 3-8 Running mode
Acceleration time t
a
=0.1[s] Constant speed time t
b
=0.8[s]
Deceleration time t
d
=0.1[s] Cycle time t
c
=2[s]
Movement distance 0.3[m]
3) Mass of the Ball Screw
2
2
3
0.02
7.9 10 0.5 1.24( )
22
  


        




D
WL
B
B B kg
4) Load Inertia
2
2
2
1
84 

     
AP
L C B C W D
WB
J J J J B B
 
2 2 2
0.00001 1.24 0.02 8 10 0.02 4      
=1.73×10
-4
[kg•m
2
]
5) Preselect Motor
If a motor with output capacity of 0.2kW is selected, then J
M
=0.14×10
-4
[kg•m
2
].
6) Inertia Ratio
J
L
/J
M
=1.73×10
-4
/0.14×10
-4
[kg•m
2
]=12.3 times <30 times
If a motor with output capacity of 0.1kW is selected, then J
M
=0.051×10
-4
[kg•m
2
]. The result is 33.9 times,
larger than 30 times.