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Static safety factor

f


s = = =33.9C C P
max P
1aE

Rated life span

Average loadRated life spanf
3

P

m

= (P R

1E3 S

1095+P

1aE3

52.5+P

1dE3

52.5) =790 N1

3

L =

( )

C f

w

? P

m

50=3.25 10

6

km

W : load factor

Evaluating the Rated Life Span of the Ball Screw Axial load

During forward uniform motionFa
1 = µ ?m
g +f=4 N µ : friction coefficient (0.005)f: rolling resistance of individual KR block + seal resistance (2.5 N)During forward accelerationFa
2 = Fa
1 +m α =76 NDuring forward decelerationFa
3 =Fa
1 -m α =-68 NDuring reverse uniform motionFa
4 =-Fa
1 =-4 NDuring reverse accelerationFa
5 =Fa
4 -m α =-4 NDuring reverse decelerationFa
6 =Fa
4 +m α =68 N* Fa
3 , Fa
4 and Fa
5 are taken to be zero as the load groove is different from the evaluated groove.

Static safety factor

f


s = = =122.2C aFa C aFa
max 2

Buckling load

2

P

1

= n ? π ? E ? I 0.5 =11000 N R

a2 P
1 : buckling load(N) R
a : distance between two mounting surfaces(1300 mm)E: Young’s modulus(2.06 10
5 N/mm
2 )n: installation procedure coefficient(fixed-fixed 4.0)0.5: safety factor l: min. geometrical moment of inertia of screw shaft(mm
4 )

I= ? d π 64

14 d
1 : screw shaft thread diameter(17.5 mm)

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