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Influence of real surface topography on the contact area ratio in differently manufactured spur gears
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.ORCID iD: 0000-0003-4447-3363
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.ORCID iD: 0000-0002-2578-9453
2012 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 56, 72-80 p.Article in journal (Refereed) Published
Abstract [en]

Surface topography measurements from spur gears produced using four different manufacturing methods were used as input to a contact analysis programme. All test gears were case-hardened, two gears were machined in the hardened state using honing and grinding respectively, and two gears were machined in the non-hardened state using hobbing and hobbing followed by green-shaving respectively. The results show that the surface topography caused by the manufacturing methods has a large influence on the real contact area in the early life of the gear. The green-shaved gear surfaces and the honed gear surfaces have the highest contact area ratio after manufacturing (as-manufactured), which could be advantageous for future gear life with respect to e.g. the running-in process.

Place, publisher, year, edition, pages
2012. Vol. 56, 72-80 p.
Keyword [en]
Surface topography, Contact mechanics, Spur gears, Finishing
National Category
Tribology
Identifiers
URN: urn:nbn:se:kth:diva-102738DOI: 10.1016/j.triboint.2012.06.014ISI: 000308284000009Scopus ID: 2-s2.0-84864052908OAI: oai:DiVA.org:kth-102738DiVA: diva2:556270
Funder
Vinnova
Note

QC 20120925

Available from: 2012-09-25 Created: 2012-09-24 Last updated: 2017-12-07Bibliographically approved
In thesis
1. On tribological design in gear tooth contacts
Open this publication in new window or tab >>On tribological design in gear tooth contacts
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact.

In this thesis the variation in surface topography inherent in the manufacturing method has been shown, by experimental work and computer simulations, to be an important factor for the contact condition in the early life of gears. Surface analysis revealed that the formation and composition of surface boundary layers depends strongly on the chemical composition of the lubricant, but also on pre-existing surface boundary layers. Additionally, surface boundary layers play a major role in frictional behaviour, wear and in allowing the lubricant to react properly with the surfaces.

Paper A presents the current ISO 6336 calculation of surface durability. A robust design approach was used to investigate the extent to which the current standard for calculation of surface durability allows for manufacturing variations and the choice of lubricant.

Paper B investigates the extent to which a logarithmical profile modification can increase gear contact pressure robustness compared to traditional lead profiles for gears.

Paper C compares different gear manufacturing methods and their as-manufactured (fresh unworn) surface topographies, using measured surface topographies as input to a contact simulation program.

Paper D examines surface boundary layer formation and the corresponding wear in relation to different anti-wear additives in an environmentally adapted base oil.

Papers E and F make use of specimens with surface topographies imitating two gear manufacturing methods (grinding and superfinishing) to be used in a twin-disc and barrel-on-disc machine respectively. The contacts are analysed by friction measurements and simulations combined with methods for surface analysis.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 40 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2012:18
Keyword
friction, gear contact, gear manufacturing, surface boundary layers, surface topography, wear
National Category
Mechanical Engineering Other Mechanical Engineering Tribology
Identifiers
urn:nbn:se:kth:diva-102742 (URN)978-91-7501-493-7 (ISBN)
Public defence
2012-10-15, Studion Gladan, Brinellvägen 85, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20120925

Available from: 2012-09-25 Created: 2012-09-24 Last updated: 2012-09-25Bibliographically approved
2. Influence of running-in on gear efficiency
Open this publication in new window or tab >>Influence of running-in on gear efficiency
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The general trend in gear industry is an increased focus on gear transmission efficiency. This thesis focuses on the understanding of how different gear manufacturing methods – particularly the contribution of the running-in process – affect the surface characteristics and friction response, with the purpose of increasing gearbox efficiency. The thesis consists of a summary and five appended papers.

The research hypothesis in paper A and paper B was that the dry elastic contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions. The emphasis in paper B is the changes that occur during running-in and correlating these changes to design requirements. Paper C examines the influence of manganese phosphate coating and lubricants, with respect to friction and the risk of scuffing at the initial contact. Paper D examines the effect of running-in load on the friction response for different surfaces. In paper E, the question of whether the load during running-in influences the gear mesh efficiency is further expounded.

The main conclusions of this thesis are that the running-in influences the gear mesh efficiency; a high running-in load enhances the gear mesh efficiency. The difference in mesh efficiency is in the range of one tenth of a per cent. Thus, the influence of running-in cannot be neglected because it is in the same order of magnitude as reported for other gear efficiency enhancements. Furthermore, the dry elastic contact area ratio presents a descriptive measure of how surface topography influences the contact, at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. Shaving was found to have the highest contact area ratio, and would therefore be the best choice if deviations from case hardening could be minimised. It was also confirmed that surfaces coated with manganese phosphate raise the limiting load for scuffing failure up to 13 times compared to the uncoated ground equivalent.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 56 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2014:09
Keyword
gears; gear manufacturing; running-in; efficiency, friction, surface topography
National Category
Tribology
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-152699 (URN)978-91-7595-258-1 (ISBN)
Public defence
2014-10-24, Sal B242, Brinellvägen 83, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20141002

Available from: 2014-10-02 Created: 2014-10-01 Last updated: 2014-10-02Bibliographically approved

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Bergseth, EllenBjörklund, Stefan

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