Page 54 - CATALOGUE

b. Ball screw shaft is fixed at both ends

Fixed Fixed

……………………………………(8)

When a=b=L/2, K has the minimum value and the elastic displacement
s
is maximum

2) Axial rigidity of the ball nut

With different preload,the rigidity of ball nut vary significantly

a. Rigidity of the nut with axial play

Theoretical rigidity value is shown in the dimension table when an axial load equivalent to 30% of
the basic dynamic load rotary (Ca) is applied. The criterion of the ball nut rigidity is 80% of the
value listed in the table taking into consideration of deformation of the ball nut,etc.
The rigidity value is obtained by the following formula when the axial load is not 30%of (Ca).

……………………………………(9)

K n: Axial rigidity of the ball nut (N/μm)
K: Rigidity value in dimension tables (N/μm)
F a: Axial load (N)
C a: Basic dynamic load rating (N)

b. Rigidity of the preload ball nut

Theoretical rigidity of preload ball nut under an axial load is shown in eachdimension table when a
preload equivalent to 10%of the basic dynamic load ratingis applied. The criterion for calculation of
nut rigidity is 80% of the value listed in the table taking into consideration of deformation of the ball
nut, etc.
Rigidity is obtained by the following formula when preload is not 10% of (C a).
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