STAR – Precision Ball Screw Assemblies

STAR – Precision Ball Screw Assemblies
Design Calculations
Upon request, we can perform all
calculations to your specifications.
Average Speed and
Average Load
– where the speed fluctuates, the
average speed n m is calculated as
follows
– where the load fluctuates and the
speed is constant, the average load F m
is calculated as follows:
– where both the load and the speed
fluctuate, the average load F m is
calculated as follows:
L (service life in revolutions)
Nominal Life
L h (service life in hours)
Drive Torque and Drive Power
Drive torque M ta
for conversion of rotary motion into
linear motion:
Transmitted torque M te
or conversion of linear motion into
rotary motion:
! see “Design Calculation Service Form“
on page 102
Where the speed and load fluctuate, the
service life must be calculated using the
averages F m and n m .
q q
n 1
m + 2 qn n1 n nn
100 100 2 100
F m 3
F 3 3
am F1 L C F m
3
F1 3
q1 3 q q 2 3 n
100
F2 100
Fn 100
n 1
n m
10 6
L
L h n m 60 7
q 3
3 q 1 n q
F 2 2 n n
2
F n
100 n
100 nm 100
n m
⇒ 3
C F L ⇒
m F C
4 5 m 6
10 6
Machine service life = L h ·
M ta
M te
F P
2000 π η
F P
2000
η
π
10
1
2
n m = average speed (min -1 )
q = discrete time step (%)
F m = average load (N)
q = discrete time step (%)
3
3 L
10 6
F m = average load (N)
q = discrete time step (%)
n m = average speed (min -1 )
The dynamic drag torque must be taken into account for preloaded nuts.
L = service life
(revolutions)
F m = average
load (N)
C = dynamic load
rating (N)
M ta = drive torque (Nm)
M te = transmitted torque (Nm)
F = operating load (N)
P = lead (mm)
η = mech. efficiency (ca. 0.9)
η´ = mech. efficiency (ca. 0.8)
Drive Power Pa Pa = drive power (kW)
Mta = drive torque (Nm)
n = speed (min-1 M
P ta n
a 9550 11
)
9
L h = service life (h)
L = service life (revolutions)
n m = average speed (min -1 )
Machine operating hours
Ball screw operating hours
94 RE 83 301/12.99
8