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Analysis of efficiency of spur ground gears and the influence of running-in
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).ORCID iD: 0000-0002-2347-8379
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Tribologi.ORCID iD: 0000-0003-2489-0688
2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 93, 172-181 p.Article in journal (Refereed) Published
Abstract [en]

High-performing gear transmissions are needed to reduce CO2 emissions. In this paper an FZG gear test rig was used to investigate how two running-in loads affects the gear mesh efficiency for two different temperatures. The gear surface roughness was investigated in parallel with testing. Higher efficiency was observed for tests using a high running-in load, and for low lubricant temperatures. The running-in load had a larger effect on the mesh efficiency than temperature. The high running-in load also yielded higher gear mesh efficiency and had a larger impact on surface parameters.

Place, publisher, year, edition, pages
Elsevier, 2016. Vol. 93, 172-181 p.
Keyword [en]
Running-in, Gears, Efficiency, Surface roughness
National Category
Tribology
Identifiers
URN: urn:nbn:se:kth:diva-173899DOI: 10.1016/j.triboint.2015.08.045ISI: 000366787700020Scopus ID: 2-s2.0-84942909258ISBN: 978-1-78242-195-5 (print)ISBN: 978-1-78242-194-8 (print)OAI: oai:DiVA.org:kth-173899DiVA: diva2:855785
Funder
Swedish Energy Agency, 35078-1, 35557-1
Note

QC 20160121

Available from: 2015-09-22 Created: 2015-09-22 Last updated: 2017-09-28Bibliographically approved
In thesis
1. Running-in of gears from a surfacetransformation and efficiency point of view
Open this publication in new window or tab >>Running-in of gears from a surfacetransformation and efficiency point of view
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Requirements today for machines have moved beyond functionality intoefficiency and reliability, gears are no exception. The presented work focuseson the analysis of the measurement, evolution and effect of running-in on geardrives from a surface roughness and efficiency point of view. With no consen-sus on a definition or observation of running-in of gear drives, measurementsof both efficiency and surface transformation during the predefined running-inis explored. A verified methodology on how to separate form, waviness androughness is presented. Two finishing methods, namely generation groundand superfinished, are analyzed in terms of efficiency and surface characteris-tics as manufactured, after running-in and after efficiency testing in order todetermine the effects of load level during running-in.Results show that separation of form can be achieved with a carefullychosen polynomial, while waviness is more subject to how the user definesa cut-off wavelength for the surface roughness. Ground gears show distinctsmoothening in terms of surface roughness at high running-in load, and nogeneral trend for low load. This behavior is also reflected in the efficiencysince higher loads gave overall lower efficiency after running-in when com-pared to lower loads. Superfinished gears in contrast show no running-in ef-fects in terms of efficiency. Additionally, ground gears exhibit general changein friction and surface roughness during the first cycles of running-in whenanalyzing high load. Overall gains in efficiency can be obtained from running-in; however, at most speeds improvements from polishing a surface, in thiscase superfinishing, proved to lead to higher efficiency.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xi, 53 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2015:06
Keyword
running-in, surface transformation, efficiency, gears, ground, su- perfinished
National Category
Tribology
Research subject
Energy Technology; Machine Design
Identifiers
urn:nbn:se:kth:diva-173828 (URN)978-91-7595-688-6 (ISBN)
Presentation
2015-10-16, Sal Gladan, Brinellvägen 85, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 35557-1
Note

QC 20150922

Available from: 2015-09-22 Created: 2015-09-18 Last updated: 2015-09-22Bibliographically approved
2. An experimental investigation of spur gear efficiency and temperature: A comparison between ground and superfinished surfaces
Open this publication in new window or tab >>An experimental investigation of spur gear efficiency and temperature: A comparison between ground and superfinished surfaces
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on reliability when testing gear efficiency and on how gear mesh efficiency can be increased without detrimental effects on the gears. Test equipment commonly used in gear research was analysed to identify important parameters for gear efficiency testing. The effect of the bearing model's load-dependent losses on gear mesh efficiency was also investigated. Two different surface finishes of gears, ground and superfinished, were investigated to determine how two different load levels during running-in affect gear mesh efficiency and changes in surface roughness. Efficiency and gear temperature were also measured for ground and superfinished gears with dip lubrication, as well as two different forms of spray lubrication (before and after gear mesh contact).

Tests on a gear test rig, showed that different assemblies of the same test setup can yield different measurements of torque loss. The applied bearing model had a significant effect on the estimated gear mesh efficiency. The mesh efficiency of ground gears is affected by the running-in procedure, with a higher running-in load resulting in a higher mesh efficiency than a lower load. This effect was not seen for superfinished gears, which show the same gear mesh efficiency for both running-in loads. Gearbox efficiency increased with spray lubrication rather than dip lubrication. The gear mesh efficiency increased, and thus gear temperatures were reduced, when superfinished gears were used rather than ground gears. A lower gear temperature was measured when gears were spray lubricated at the mesh inlet rather than the mesh outlet.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 51 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2017:02
Keyword
gears, ground, superfinished, efficiency, temperature, running-in, dip lubrication, spray lubrication
National Category
Tribology
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-202990 (URN)
Public defence
2017-03-31, Gladan, Brinellvägen 85, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170314

Available from: 2017-03-14 Created: 2017-03-10 Last updated: 2017-03-14Bibliographically approved
3. Running-in of gears - surface and efficiency transformation
Open this publication in new window or tab >>Running-in of gears - surface and efficiency transformation
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With ever shorter development times and market demands on overall system performance such as efficiency, reliability and low maintenance, accurate predictive tools are necessary and gear drives prove to be no exception. All these characteristics have an impact on a process which has remained a riddle: running-in. Even though no consensus on a definition of this phenomena is readily available, this thesis examines efficiency, surface roughness and simulation through the optics of running-in.

Geared transmissions are known for their formidable efficiency and their extreme reliability. However, with an ever increasing power density, the ability to accurately predict mesh losses becomes of utmost importance. The accurate quantification of bearing losses as well as efficiency of ground and superfinished gears under dip lubrication are examined with respect to running-in. Results show a considerable influence on the calculation of gear mesh losses originating from which bearing loss model is chosen. Furthermore, when a larger running-in load is used on ground gears, an increase in efficiency can be observed during working operation, while for superfinished no significant changes are found. These efficiency/frictional changes are also shown to occur in the initial cycles of the running-in phase.

From a surface transformation point of view running-in is shown to be a reduction of asperity tips in case hardened ground gears, while in superfinished gears no changes were seen. These gear surface changes were measured with a novel method with a surface profilometer in-situ before, after running-in and after efficiency testing. Results also show that such changes in ground gear roughness profile occur during the very initial cycles.

In order to predict running-in, a simulation method was developed. Such method utilizes a 2D surface integral method to simulate contact between rough surfaces, but requires the use of surface hardness and an accurate lower cutoff wavelength. This cutoff wavelength proved to play a pivotal role in determining an accurate contact pressure at the proper level of granularity, hence a well defined real contact area. The predicted and measured run-in surfaces are compared and are found to be in accordance with each other.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 77 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2017:12
Keyword
running-in, surface transformation, efficiency, gears, ground, superfinished
National Category
Tribology
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-214983 (URN)978-91-7729-520-4 (ISBN)
Public defence
2017-11-17, Gladan, Brinellvägen 83, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170928

Available from: 2017-09-28 Created: 2017-09-27 Last updated: 2017-09-28Bibliographically approved

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Sosa, MarioOlofsson, Ulf

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