Screwjack effects of wear on thread stripping load



Purpose of calculation:
Calculate thread stripping load on ACME leadscrew
Determine effects of wear on thread stripping load.
This calculation is featured as a case study.

Calculation Validation
Check against manufacturers recommendations

Select Acme Leadscrew thread Size (dia. - threads per inch)

  1. Leadscrew Dimensions
    Outside diameter of thread
    Thread Pitch
    Inside diameter of thread
    Manufacterer's (Roton) Static Load Rating
    Manufacterer's (Roton) Operating Load Rating
    Thread angle
    Shear thickness per thread

  2. Estimate wear allowance
    Maximum clearance and wear allowed
    Nut/collar thickness
    Shear Area

  3. Nut material properties and nut shear strength calculation
    Calculated operating load
    Correlation between calculated and manufacturers value

  4. Calculate normal loading with maximum allowable load nut wear
    Force on leadscrew
    Operating load

  5. Calculate wear for nut thread stripping
    Critical Clearance/Wear Limit for nut stripping
    Amount of wear for nut stripping

  6. Estimate Wear
    Bearing stress
    Rubbing Distance
    Surface Hardness (Brinell Hardness in kg/mm2 convered to psi)
    Wear Coefficients from ExcelCalcs Repository
    Unlubricated wear depth in 6 months - Ref. Juvinall Eqn. (9.1)
    Time to unlubricated load nut failure
    Lubricated wear depth in 6 months
    Time to lubricated load nut failure

    Calculation Reference
    Fundamentals Of Machine Component Design - Juvinall

Machinery's Handbook

Mechanical Engineers' Handbook

Schaum's Outline - Machine Design

Calculation Preview

28 Jan 2010
File Size: 182.00 Kb
Downloads: 71
File Version: 1.0
File Rating (5/2)

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