WEIHONG WISE WSDV-6R820PSB - 3.5 Motor Selection Calculations and Torque Types; Constant Torque and Holding Torque; Effective Torque Calculation

Specialized Concentrated Focused
「24」Servo Motor
Acceleration torque:
a
( ) 2
Running torque
LM
psa
J J N
T
t
 

(Unit: N·m)
Deceleration torque:
d
( ) 2
Running torque
LM
d
ps
J J N
T
t
 
 -
(Unit: N·m)
J
L
: Load moment of inertia (unit: kg·m
2
)
J
M
: Rotor moment of inertia (unit: kg·m
2
)
N: Motor rotational speed (unit: r/s)
2) Constant Torque and Holding Torque when Stopping
Constant torque and holding torque when stopping are the torque required when motor keeps rotating
for a long time, whose value is approximate 80% less of rated torque of the motor. If the value is negative,
a regenerative resistor may be needed.
Calculate torques of different driving systems according to the following formulas.
Driving system
Formula for T
Ball screw
W
P
F
Constant torque
f
P
( gW+F)
2
T 


W:Mass [kg] η:Mechanical effiency
P:Guide travel [m] μ:Friction coefficient
F:External force [N] g:Gravitational acceleration
9.8[m/s
2
]
Belt driving system
D
F
W
Constant torque
f
D
( gW+F)
2
T 


W:Mass[kg] η:Mechanical effiecncy
D:Guide travel [m] μ:Friction
coefficient
F:External force [N] g:Gravitational
acceleration 9.8[m/s
2
]
Rotating parts
Z
1
Z
2
T
Lo
Constant torque
f L0 F
11
T +T
n 
  T
T
L0
:Load torque T
F
:Load friction torque
1/n:Electronic gear ratio
2
1
Z
n=
Z
η:Mechanical effiency