Calculates power screws loaded by torsion and pressure, and checks for buckling and pressure in the thread using metric or English units, depending on the specified standard. With the ANSI standard, English units are used with corresponding screw dimensions.
Input Parameters
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F |
maximal axial force [N, lb] |
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T |
maximal.moment [Nm, lb ft] |
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f 1 |
thread friction factor between the nut and screw [-] Note: The influence of the angle of thread must be included in the thread friction factor value.
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d |
screw thread diameter [mm, in] |
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p |
pitch [mm, in] |
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d s |
mean screw diameter [mm, in] |
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d min |
minimum screw diameter [mm, in] |
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H |
nut height [mm, in] |
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n |
factor for end conditions according to the diagrammatic picture of mounting types [-] |
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L |
maximum loaded length of a screw [mm, in] |
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S y |
yield strength [MPa, psi] |
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k s |
safety factor (The value is selected according to the required safety level.) [-] |
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p a |
allowable thread pressure [MPa, psi] |
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E |
screw elasticity module [MPa, psi] |
Calculated Parameters
Reduced length
L red = n L
Min. section area
S min = π d min 2 / 4
Helix Angle (Lead angle)
Efficiency
For “Rotation to Shift”
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For “Shift to Rotation”
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If α < arc tan f 1 , η = 0 |
Maximum moment - if it is the output moment
T = F p / (2 πη)
Maximum axial force - if it is the output force
F = 2 T πη / p
Slenderness ratio
λ = 4 L red / d s
Pressure stress
σ t = F / S min
Torsion stress
Reduced stress
Rankin Critical Stress
Euler Critical Stress
σ E = π 2 E / λ 2
Johnson Critical Stress
Calculated thread pressure
Calculated factor of safety
k v = min (S y / σred, min (σ R , σ F , σ J ) / σ t )
Strength check
k v ≥ k s
p c ≤ p A