Gear Load-Carrying Capacity Design, Calculation And Application in Mechanical Transmission
Publish Time: 2025-12-03 Origin: Site
1. Basic Design Process for Gear Load-Carrying Capacity
2. Core Calculation Methods
2.1 Tooth Surface Contact Fatigue Strength Calculation (per ISO 6336 Standard)
σH is the calculated contact stress (MPa)
ZH denotes the zone factor, ZE the elastic coefficient of materials, Zε the contact ratio factor, and Zβ the helix angle factor
Ft represents the tangential force at the transverse pitch circle (N)
b is the face width (mm), d1 the pitch circle diameter of the pinion (mm), and u the gear ratio (u=z2/z1)
σHP is the allowable contact stress (MPa), calculated as:σHP = σHlim × ZN × ZL × Zv × ZR × ZW × ZX / SHmin(σHlim = contact fatigue limit of test gears; ZN = life factor; ZL = lubricant factor; Zv = speed factor; ZR = surface roughness factor; ZW = work hardening factor; ZX = size factor; SHmin = minimum safety factor)
2.2 Tooth Root Bending Fatigue Strength Calculation
σF is the calculated bending stress (MPa)
mn is the normal module (mm)
YF = form factor, YS = stress correction factor, Yβ = helix angle factor, YB = face width factor
σFP is the allowable bending stress (MPa), calculated as:σFP = σFlim × YN × YδrelT × YRrelT × YX / SFmin(σFlim = bending fatigue limit of test gears; YN = life factor; YδrelT = relative tooth root fillet sensitivity factor; YRrelT = relative surface condition factor; YX = size factor; SFmin = minimum safety factor)
3. Load-Carrying Capacity Verification
3.1 Basic Verification Conditions
Contact fatigue strength: σH ≤ σHP
Bending fatigue strength: σF ≤ σFP
3.2 Special Working Condition Verification
3.3 Influence of Key Factors
Geometric parameters: Module significantly enhances bending strength; number of teeth affects curvature radius and form factor (pinion z1 ≥ 17-20 is recommended); face width linearly improves both strengths (face width factor ψ_d = 0.8-1.4); helix angle increases contact length (β = 8°-15°); profile shift coefficient optimizes contact path.
Materials and processes: Carburizing and quenching (for high loads), induction hardening (for medium loads), and quenching and tempering (for general loads) are common heat treatments; shot peening enhances fatigue limit, surface coating improves wear resistance, and grinding/polishing reduces roughness.