11. Calculation formula of screw tightening force and screw turning force
11.Calculation formula of screw tightening force and screw turning force
Symbol description and unit
(1) Tightening force when tightening screws
tanÆ=P/(Î*d
0
)@(ÆF Screw lead angle)
F=T*1000*2/d
0
(Force in screw diameter)
W=F*(1-Ê*tanÆ)/(Ê+tanÆ)@kkgfl
W=
sF Torque to turn the screw@kkgfEml
ÊF Coefficient of friction of screws
P: Screw pitch [mm]
d
0
:Screw diameter [mm]
(2) Torque when loosening screws
tanÆ=P/(Î*d
0
)@(ÆF Screw lead angle)
F=W*(Ê-tanÆ)/(1+Ê*tanÆ)@
(Force in screw diameter)kkgfl
s=F*d
0
/(1000*2)@[kgf¥m]
s=
WF Screw tightening force@kkgfl
ÊFCoefficient of friction of screws
P: Screw pitch [mm]
d
0
: Screw diameter [mm]