| 1. |
- Cabanettes, Frédéric, 1982-
(författare)
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Cam Roller Contact : The topographical aspect
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry and the design of engines are strongly ruled by performance and legislation demands. First order aspects defining the main functions of a component are well known and new challenges appear at a lower scale. Wear reduction is defined as a second order problem and requires decreasing the scale of observation of components down to roughness. This thesis work and its aim lie within the scope of wear improvements and are focused on the injection cam/roller contact of heavy duty diesel engines. In order to reach the aim several material and methods are used: a valve train rig test, roughness characterisation and different manufacturing processes. It is shown by experiments that the flank and nose of injection cams are specific areas with specific roughness (higher density of summits Sds) compared to the rest of the cam. The wear is characterized by rounded-off of summits (Ssc). From those results and since wear processes are strongly linked to the pressure generated between the mating surfaces, the development of a rough contact model is of great interest. An elastic rough contact model is implemented and improved later on by an elasto-plastic description of materials. The simulations are validated by a wear test and are used to rank the ability of surfaces (both cam and roller) to face wear problems. The ratio of plastically deformed peaks shows that the flank and nose of the cam are reacting badly to pressures. Additionally the rough contact allows ranking/optimization of different machining processes with respect to their expected functional contact performance. Future work will be to use such a model to choose a good combination of surfaces (cam and roller) in order to reduce wear.
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| 2. |
- Cabanettes, Frédéric, 1982-
(författare)
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Cam Roller Contact : Surfaces and Tribology
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry and the design of engines are strongly ruled by performance and legislation demands. In the valve train, mechanical components such as camshafts and rollers are defined by specifications including more and more constraints concerning their ability to face wear thus prolonging lifetime.The aim of the thesis is to develop tools facilitating the choice between different manufacturing processes for wear optimization purposes of cam and roller components for IC engine valve trains. Tools are both experimental and theoretical.For the experimental part, statistical and relocated studies of wear have been performed. It is shown that measuring the very same surface before and after experiments is preferable to understand wear mechanisms of cams and rollers. A set of analysis tools for describing changes between unworn and relocated worn surfaces is developed. As results, it is found that the predominant mechanism of wear for cams and rollers is a flattening of asperities: surfaces are pressed and plastic deformations occur.In parallel, simulations have been developed to explain theoretically the wear observed. Micro and macro simulations are developed to predict the ability of a given manufacturing process to resist wear. For the microscopic simulation, a rough contact model including elasto-plastic behavior of materials is used and shows good correlations with experiments. Concerning the macroscopic simulation, a model including form deviations due to manufacturing is developed and computes oil film thicknesses and deformations. The different parameters computed by both simulations are indicators of the wear performance of different surfaces. It is shown that such simulation can rank different manufacturing processes in terms of ability to face wear.
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| 3. |
- Cabanettes, Frederic, 1982
(författare)
-
Cam Roller Contact
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry and the design of engines are strongly ruled by performance andlegislation demands. First order aspects defining the main functions of a component are wellknown and new challenges appear at a lower scale. Wear reduction is defined as a second orderproblem and requires decreasing the scale of observation of components down to roughness.This thesis work and its aim lie within the scope of wear improvements and are focusedon the injection cam/roller contact of heavy duty diesel engines. In order to reach the aimseveral material and methods are used: a valve train rig test, roughness characterisation anddifferent manufacturing processes.It is shown by experiments that the flank and nose of injection cams are specific areas withspecific roughness (higher density of summits Sds) compared to the rest of the cam. The wearis characterized by rounded-off of summits (Ssc). From those results and since wear processesare strongly linked to the pressure generated between the mating surfaces, the development ofa rough contact model is of great interest.An elastic rough contact model is implemented and improved later on by an elasto-plasticdescription of materials. The simulations are validated by a wear test and are used to rankthe ability of surfaces (both cam and roller) to face wear problems. The ratio of plasticallydeformed peaks shows that the flank and nose of the cam are reacting badly to pressures. Additionallythe rough contact allows ranking/optimization of different machining processes withrespect to their expected functional contact performance.Future work will be to use such a model to choose a good combination of surfaces (camand roller) in order to reduce wear.
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| 4. |
- Cabanettes, Frederic, 1982, et al.
(författare)
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Evaluation of cam and roller surfaces and their manufacturing process by functional characterisation
- 2008
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Ingår i: Proceedings of the Swedish Production Symposium 2008, Stockholm, Sweden. ; , s. 7-
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Konferensbidrag (refereegranskat)abstract
- Friction and wear are constant problems encountered in camshaft development. Thecontact between roller and cam is a mix of sliding and rolling which leads to a wide rangeof failure modes. The uniqueness of this contact is also due to variations all around thecam of a multitude of parameters. A previous study described surface topography as afunction of cam shape. The different types of wear mechanisms are strongly linked tocontact pressures which are also dependent on roughness. The aim of the paper is toevaluate the quality of camshafts and rollers produced with different manufacturinghistories. The evaluation utilises standard roughness parameters as well as rough contactparameters. The surfaces measurements are made by a non-contact light interferometerand a set of 3D roughness parameters is evaluated for each measure. The Greenwood-Williamson contact model has been developed and also applied to the measurements inorder to collect characteristics of the microscopic pressures. The results of the study showthe significant effect of topography variations on the tribological behaviour of the camroller contact and rank the different manufacturing processes according to functionalcharacterization. The verification of the ranking using experiments is the continuity of thisstudy.
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| 5. |
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| 6. |
- Cabanettes, Frederic, 1982, et al.
(författare)
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Evaluation of cam and roller surfaces by wear testing and functional characterisation
- 2008
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Ingår i: Proceedings of the 35th Leeds Lyon Symposium on Tribology. ; , s. 8-
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Konferensbidrag (refereegranskat)abstract
- Friction and wear are constant problems encountered in camshaft development. The contact between roller and camis a mix of sliding and rolling which leads to a wide range of failure modes. The uniqueness of this contact is also dueto variations all around the cam of a multitude of parameters such as load and radius. A previous study describedsurface topography as a function of cam shape. The different types of wear mechanisms are strongly linked to contactpressures which are also dependent on roughness. The aim of the paper is to develop a rough contact model which willbe utilized as a tool to rank surfaces and their ability to face wear problems. In order to verify the tool, rough contactresults are compared to roughness parameter variations due to wear produced in a cam roller rig test. The surfacemeasurements used for this study are made by a non-contact light interferometer. The Greenwood-Williamson contactmodel has been developed in a deterministic way and the elasto-plastic behaviour of the material has been integratedto the model. The outputs of the simulation give a ranking of surfaces which is compared to their roughness variationsdue to wear. The study shows that the model developed is a reliable tool to rank and define surface quality since theresults are correlated to wear. However, the results show as well some discrepancies which could be corrected in thefuture by integrating to the model two new features: a rough to rough contact including sliding between surfaces. Thisnew model should be verified by an accurate experimentation using relocation between unworn and worn surfaces.
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| 7. |
- Cabanettes, Frédéric, 1982-, et al.
(författare)
-
Evaluation of cam surfaces by wear testing and functional characterization
- 2008
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Ingår i: Synopses / 35th Leeds-Lyon Symposium on Tribology. - Leeds : Leeds University.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Friction and wear are constant problems encountered in camshaft development. The contact between roller and cam is a mix of sliding and rolling which leads to a wide range of failure modes. The uniqueness of this contact is also due to variations all around the cam of a multitude of parameters such as load and radius. A previous study described surface topography as a function of cam shape. The different types of wear mechanisms are strongly linked to contact pressures which are also dependent on roughness. The aim of the paper is to develop a rough contact model which will be utilized as a tool to rank surfaces and their ability to face wear problems. In order to verify the tool, rough contact results are compared to roughness parameter variations due to wear produced in a cam roller rig test. The surface measurements used for this study are made by a non-contact light interferometer. The Greenwood-Williamson contact model has been developed in a deterministic way and the elasto-plastic behaviour of the material has been integrated to the model. The outputs of the simulation give a ranking of surfaces which is compared to their roughness variations due to wear. The study shows that the model developed is a reliable tool to rank and define surface quality since the results are correlated to wear. However, the results show as well some discrepancies which could be corrected in the future by integrating to the model two new features: a rough to rough contact including sliding between surfaces. This new model should be verified by an accurate experimentation using relocation between unworn and worn surfaces.
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| 8. |
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| 9. |
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| 10. |
- Cabanettes, Frederic, 1982-, et al.
(författare)
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Global and local mapping of motor blocks liners roughness for the analysis of honing performance
- 2014
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Ingår i: Journal of physics. - Bristol : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 483:1
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Tidskriftsartikel (refereegranskat)abstract
- The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear at both global (due to honing tool wear) and local (TDC, middle stroke, BDC) scales and need to be mapped and analysed. The following paper proposes to map the global and local variations in roughness by using a confocal 3D measuring equipment able to measure and scan any area of a cylinder liner. Six motor blocks (five liners each) are evaluated with twenty topography measurements per liner. In total, six hundred 3D measurements of size 1×1 mm are performed and roughness parameters are computed. The results show that some parameters do correlate with the honing tool wear specific to each cylinder. Experimental models could be built. Furthermore surface roughness varies significantly over the axial length of the liners due to waviness deviations combined with a lack of flexibility of the honing tool in axial direction. © Published under licence by IOP Publishing Ltd.
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