ISO/TS 6336-4:2019
(Main)Calculation of load capacity of spur and helical gears — Part 4: Calculation of tooth flank fracture load capacity
Calculation of load capacity of spur and helical gears — Part 4: Calculation of tooth flank fracture load capacity
This document describes a procedure for the calculation of the tooth flank fracture load capacity of cylindrical spur and helical gears with external teeth. It is not intended to be used as a rating method in the design and certification process of a gearbox. The formulae specified are applicable for driving as well as for driven cylindrical gears while the tooth profiles are in accordance with the basic rack specified in ISO 53. They can also be used for teeth conjugate to other racks where the actual transverse contact ratio is less than εα = 2,5. The procedure was validated for case carburized[15] gears and the formulae of this document are only applicable to case carburized gears with specifications inside the following limits: — Hertzian stress: 500 N/mm2 ≤ pH ≤ 3 000 N/mm2; — Normal radius of relative curvature: 5 mm ≤ ρred ≤ 150 mm; — Case hardening depth at 550 HV in finished condition: 0,3 mm ≤ CHD ≤ 4,5 mm. This document is not applicable for the assessment of types of gear tooth damage other than tooth flank fracture.
Calcul de la capacité de charge des engrenages cylindriques à dentures droite et hélicoïdale — Partie 4: Calcul de la capacité de charge de la rupture en flanc de dent
General Information
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 6336-4
First edition
2019-01
Corrected version
2019-07
Calculation of load capacity of spur
and helical gears —
Part 4:
Calculation of tooth flank fracture load
capacity
Calcul de la capacité de charge des engrenages cylindriques à
dentures droite et hélicoïdale —
Partie 4: Calcul de la capacité de charge de la rupture en flanc de dent
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
3.3 Definition of local contact point, CP, and material depth, y . 3
4 Definition of tooth flank fracture . 4
5 Basic formulae . 5
5.1 General . 5
5.2 Maximum material exposure, A . 5
FF,max
5.3 Local material exposure, A (y) . 6
FF,CP
6 Local occurring equivalent stress, τ (y) . 7
eff,CP
6.1 General . 7
6.2 Local equivalent stress without consideration of residual stresses, τ (y) . 7
eff,L,CP
6.2.1 General. 7
6.2.2 Local normal radius of relative curvature, ρ . 8
red,CP
6.2.3 Reduced modulus of elasticity, E . 8
r
6.2.4 Local Hertzian contact stress, p . 9
dyn,CP
6.3 Quasi-stationary residual stress, τ (y) .21
eff,RS
6.3.1 General.21
6.3.2 Method A .21
6.3.3 Method B .21
6.4 Influence of the residual stresses on the local equivalent stress, ∆τ (y) .22
eff,L,RS,CP
7 Local material strength, τ (y).23
per,CP
7.1 General .23
7.2 Hardness conversion factor K .23
τ,per
7.3 Material factor K .23
material
7.4 Hardness depth profile, HV(y) .25
7.4.1 General.25
7.4.2 Method A .25
7.4.3 Method B .25
7.4.4 Method C1 .26
7.4.5 Method C2 .26
Annex A (informative) Calculation of local equivalent stress without consideration of
residual stresses, τ (y) .28
eff,L,CP
Bibliography .29
Foreword
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electrotechnical standardization.
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different types of ISO documents should be noted. This document was drafted in accordance with the
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 60, Gears, Subcommittee SC 2, Gear
capacity calculation.
A list of all parts in the ISO 6336 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
This corrected version of ISO 6336-4:2019 incorporates the following corrections:
— mistakes in the formulae have been corrected.
iv © ISO 2019 – All rights reserved
Introduction
The ISO 6336 series consists of International Standards, Technical Specifications (TS) and Technical
Reports (TR) under the general title Calculation of load capacity of spur and helical gears (see Table 1).
— International Standards contain calculation methods that are based on widely accepted practices
and have been validated.
— Technical Specifications (TS) contain calculation methods that are still subject to further
development.
— Technical Reports (TR) contain data that is informative, such as example calculations.
The procedures specified in ISO 6336-1 to ISO 6336-19 cover fatigue analyses for gear rating. The
procedures described in ISO 6336-20 to ISO 6336-29 are predominantly related to the tribological
behaviour of the lubricated flank surface contact. ISO 6336-30 to ISO 6336-39 include example
calculations. The ISO 6336 series allows the addition of new parts under appropriate numbers to reflect
knowledge gained in the future.
Requesting standardized calculations according to the ISO 6336 series without referring to specific
parts requires the use of only those parts that are currently designated as International Standards (see
Table 1 for listing). When requesting further calculations, the relevant part or parts of the ISO 6336
series need to be specified. Use of a Technical Specification as acceptance criteria for a specific designs
need to be agreed in advance between the manufacturer and the purchaser.
Table 1 — Parts of the ISO 6336 series (status as of DATE OF PUBLICATION)
International Technical Technical
Calculation of load capacity of spur and helical gears
Standard Specification Report
Part 1: Basic principles, introduction and general influ-
X
ence factors
Part 2: Calculation of surface durability (pitting) X
Part 3: Calculation of tooth bending strength X
Part 4: Calculation of tooth flank fracture load capacity X
Part 5: Strength and quality of materials X
Part 6: Calculation of service life under variable load X
Part 20: Calculation of scuffing load capacity (also
applicable to bevel and hypoid gears) — Flash tempera-
X
ture method
(replaces: ISO/TR 13989-1)
Part 21: Calculation of scuffing load capacity (also ap-
plicable to bevel and hypoid gears) — Integral tempera-
X
ture method
(replaces: ISO/TR 13989-2)
Part 22: Calculation of micropitting load capacity
X
(replaces: ISO/TR 15144-1)
Part 30: Calculation examples for the application of
X
ISO 6336 parts 1, 2, 3, 5
Part 31: Calculation examples of micropitting load capacity
X
(replaces: ISO/TR 15144-2)
This document provides principles for the calculation of the tooth flank fracture load capacity of
cylindrical involute spur and helical gears with external teeth. The method is based on theoretical and
experimental investigations (see References [9], [10], [12] and [15]) on case carburized test gears and
gears from different industrial applications.
This document as a part of the ISO 6336 series includes a newly developed method for assessing the
risk of tooth flank fracture, which is still subject to further development. It is published in order to gain
a broader experience with the obtained results in various scopes of application. The knowledge gained
will serve for further development and refinement of this document.
Tooth flank fracture is characterized by a primary fatigue crack in the region of the active contact area,
initiated below the surface due to shear stresses caused by the flank contact. Failures due to tooth
flank fracture are reported from different industrial gear applications and have also been observed on
specially designed test gears for gear running tests. Tooth flank fracture is most often observed on case
carburized gears but failures are also known for nitrided and induction hardened gears. Most of the
observed tooth flank fractures occurred on the driven partn
...
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