Mathematical
formulas for
calculation
Data
Frictional moment M
Moment for
overcoming the force
of gravity M
G
Machining moment
M
B
Static moment M
Stat
Desired speed of the
motor n
S
Selection of the
motor
Modular inverter:
Selection of the
power module
Compact inverter:
Selection of the axis
unit
April 2007
Formulas
R
⋅
⋅
μ
⋅
m
g
M R
=
------------------------------------------------------
⋅
π
⋅
2
⋅
⋅
⋅
m
g
h
M
=
------------------------------------------ -
⋅
π
⋅
G
2
i
⋅
F
h
B
M
=
------------------------------ -
⋅
π
⋅
B
2
i
M
=
M
+
Stat
R
⋅
v
i
max
n
=
------------------- -
S
h
≥
M
M
0Motor
Stat
≥
n
n
NMotor
S
≥
I
I
NU
0Motor
Selection of the Axis Motor
Variable
m: Mass [kg]
g: Acceleration of gravity [m/s
⋅
α
h
cos
μ: Coefficient of friction [-]
⋅
η
i
h: Ball screw pitch [m]
α: Axis angle [°]
(0° = horizontal axis)
i: Gear ratio [-]
(n
motor
η : Efficiency [-]
m: Mass [kg]
g: Acceleration of gravity [m/s
α
sin
h: Ball screw pitch [m]
⋅
η
α: Axis angle [°]
(90° = vertical axis)
i: Gear ratio [-]
(n
motor
η : Efficiency [-]
F
: Machining force [N]
B
h: Ball screw pitch [m]
i: Gear ratio [-]
⋅
η
(n
motor
η : Efficiency [-]
M
: Frictional moment [Nm]
R
M
G
M
+
M
gravity [Nm]
G
B
M
: Machining moment [Nm]
B
v
max
i: Gear ratio [-]
(n
motor
h: Ball screw pitch [m]
M
0Motor
M
Stat
n
NMotor
n
: Desired speed of the motor
S
I
: Rated current of the inverter
NU
I
0Motor
motor
/n
)
ball screw
/n
)
ball screw
/n
)
ball screw
: Moment for overcoming the force of
: Rapid traverse [m/min]
/n
)
ball screw
: Stall torque of the motor
: Static moment
: Rated speed of the motor
: Continuous stall current of the
2
]
2
]
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