Rolling of Thin Strip and Foil: Application of a Tribological Model for “Mixed” Lubrication

2001 ◽  
Vol 124 (1) ◽  
pp. 129-136 ◽  
Author(s):  
HR Le ◽  
M. P. F. Sutcliffe
Keyword(s):  
Practical Interest ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Thin Strip ◽  
Contact Ratio ◽  
Forward Slip ◽  
Lubrication Regime ◽  
Strip Drawing ◽  
Mixed Lubrication Regime ◽  
Theoretical Results

A mechanical model of cold rolling of foil is coupled with a sophisticated tribological model. The tribological model treats the “mixed” lubrication regime of practical interest, in which there is “real” contact between the roll and strip as well as pressurized oil between the surfaces. The variation of oil film thickness and contact ratio in the bite is found by considering flattening of asperities on the foil and the build-up of hydrodynamic pressure through the bite. The boundary friction coefficient for the contact areas is taken from strip drawing tests under similar tribological conditions. Theoretical results confirm that roll load and forward slip decrease with increasing rolling speed due to the decrease in contact ratio and friction. The predictions of the model are verified using mill trials under industrial conditions. For both thin strip and foil, the load predicted by the model has reasonable agreement with the measurements. For rolling of foil, forward slip is overestimated. This is greatly improved if a variation of friction through the bite is considered.

A Friction Model for Cold Strip Rolling With Two-Wavelength Surface Roughness in the “Mixed” Lubrication Regime

2003 ◽  
Vol 125 (3) ◽  
pp. 670-677 ◽  
Author(s):  
H. R. Le ◽  
M. P. F. Sutcliffe
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Rolling Direction ◽  
Hydrodynamic Pressure ◽  
Friction Model ◽  
Mixed Lubrication ◽  
Strip Rolling ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Cold Metal

A two-dimensional friction model has been developed for cold metal rolling in the “mixed” lubrication regime. Roughness is modelled using superimposed short and long wavelength asperities with a lay orientated along the rolling direction. The hydrodynamic pressure in the lubricant is solved using Reynolds’ equation, coupled with the crushing process of the two-wavelength roughness. This allows for the solution of film thickness and contact area ratio and hence friction coefficient through the roll-bite. The model extends the authors’ earlier model [15] by allowing for a variation in hydrodynamic pressure across the width of the contact. Predictions for both the surface roughness and the friction coefficient are in reasonable agreement with published measurements.

scholarly journals Modelling tribochemistry in the mixed lubrication regime

2019 ◽  
Vol 132 ◽  
pp. 265-274 ◽  
Author(s):  
Abdullah Azam ◽  
Ali Ghanbarzadeh ◽  
Anne Neville ◽  
Ardian Morina ◽  
Mark C.T. Wilson
Keyword(s):  
Mixed Lubrication ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime

Lubrication efficiency of crankpin bearing using square-cylindrical textures of partial textures optimized by genetic algorithm

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shaoyong Xu ◽  
Vanliem Nguyen ◽  
Xiaoyan Guo ◽  
Huan Yuan
Keyword(s):  
Genetic Algorithm ◽  
Mixed Lubrication ◽  
Bearing Surface ◽  
Machining Time ◽  
Obvious Effect ◽  
Content Type ◽  
Density Distributions ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime ◽  
Geometrical Dimensions

Purpose This paper aims to propose an optimal design of the partial textures in the mixed lubrication regime of the crankpin bearing (CB) to maximize the CB's lubrication efficiency. Design/methodology/approach Based on a hybrid model between the slider-crank-mechanism dynamic and CB lubrication, the square-cylindrical textures (SCT) of partial textures designed on the CB’s mixed lubrication regime are researched. The effect of the density distributions of partial textures on CB’s lubrication efficiency is then evaluated via two indices of increasing the oil film pressure (p) and decreasing the frictional force (Ff) of the CB. The SCT’s geometrical dimensions are then optimized by the genetic algorithm to further improve the CB’s lubrication efficiency. Findings The results show that the SCT of partial textures optimized by the genetic algorithm has an obvious effect on enhancing CB’s lubrication efficiency. Especially, with the CB using the optimal SCT of partial textures (4 × 6), the maximum p is significantly increased by 3.7% and 8.2%, concurrently, the maximum Ff is evidently reduced by 9.5% and 21.6% in comparison with the SCT of partial textures (4 × 6) without optimization and the SCT of full textures (12 × 6) designed throughout the CB’s bearing surface, respectively. Originality/value The application of the optimal SCT of partial textures on the bearing surface not only is simple for the design-manufacturing process and maximizes CB’s lubrication efficiency but also can reduce the machining time, save cost and ensure the durability of the bearing compared to use the full textures designed throughout the CB’s bearing surface.

A Theory of Mixed Lubrication

1972 ◽  
Vol 186 (1) ◽  
pp. 421-430 ◽  
Author(s):  
H. Christensen
Keyword(s):  
Hydrodynamic Lubrication ◽  
Dynamic Properties ◽  
Mixed Lubrication ◽  
Rapid Rise ◽  
Operating Characteristics ◽  
Lubrication Regime ◽  
Lubricated Contact ◽  
Mixed Lubrication Regime ◽  
Lubrication Conditions ◽  
Lubrication Properties

The phenomena observed when a lubricated contact or bearing is operating under mixed lubrication conditions are assumed to arise from an interaction of the surface asperities or roughness as well as from hydro-dynamic action of the sliding surfaces. It is shown how one of the previously published stochastic models of hydrodynamic lubrication can be extended or generalized to deal with mixed lubricating conditions. As an illustration of the application of the theory to a concrete example the influence on the operating characteristics of a plane pad, no side-leakage bearing is analysed. It is found that in the mixed lubrication regime friction is mainly controlled by the boundary lubrication properties of the liquid–solid interface. Load, on the other hand, is almost entirely controlled by the hydro-dynamic properties of the bearing. It is demonstrated how transition to mixed lubrication conditions will cause a rapid rise in friction thereby producing a minimum point in the Stribeck type diagram.

A numerical method to investigate the mixed lubrication performances of journal-thrust coupled bearings

2019 ◽  
Vol 71 (9) ◽  
pp. 1099-1107
Author(s):  
Guo Xiang Guo Xiang ◽  
Yanfeng Han ◽  
Renxiang Chen ◽  
Jiaxu Wang Jiaxu Wang ◽  
Ni Xiaokang
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Hydrodynamic Effect ◽  
Asperity Contact ◽  
Content Type ◽  
Lubrication Regime ◽  
Coupled Effect

Purpose This paper aims to present a numerical model to investigate the mixed lubrication performances of journal-thrust coupled bearings (or coupled bearings). Design/methodology/approach The coupled hydrodynamic effect (or coupled effect) between the journal and the thrust bearing is considered by ensuring the continuity of the hydrodynamic pressure and the flow field at the common boundary. The mixed lubrication performances of the coupled bearing are comparatively studied for the cases of considering and not considering coupled effect. Findings The simulated results show that the hydrodynamic pressure distributions for both the journal and thrust bearing are modified due to the coupled effect. The decreased load capacity of the journal bearing and the increased load capacity of the thrust bearing can be observed when the coupled effect is considered. And the coupled effect can facilitate in reducing the asperity contact load for both the journal and thrust bearing. Additionally, the interaction between the mixed lubrication behaviors, especially for the friction coefficient, of the journal and the thrust bearing is significant in the elastohydrodynamic lubrication regime, while it becomes weak in the mixed lubrication regime. Originality/value The developed model can reveal the mutual effects of the mixed lubrication behavior between the journal and the thrust bearing.

Control on wear of journal bearing operating in mixed lubrication regime using grooving arrangements

2016 ◽  
Vol 68 (4) ◽  
pp. 458-465 ◽  
Author(s):  
Lijesh K.P. ◽  
Muzakkir S.M. ◽  
Harish Hirani ◽  
Gananath Doulat Thakre
Keyword(s):  
Journal Bearing ◽  
Wear Behavior ◽  
Research Work ◽  
Theory Model ◽  
Mixed Lubrication ◽  
Experimental Investigations ◽  
Heavy Load ◽  
Content Type ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime

Purpose The journal bearings subjected to heavy load and slow speed operate in mixed lubrication regime causing contact between the interacting surfaces and resulting in wear. Complexity of wear behavior and lack of unifying theory/model make wear-control very challenging. Design/methodology/approach In the present research work, theoretical and experimental investigations have been conducted to explore the effect of grooving arrangements on the wear behavior of journal bearing operating in mixed lubrication regime. The theoretical model of Hirani (2005) that uses mass conserving cavitation algorithm has been used to determine the bearing eccentricity for different groove arrangements (with varying groove location and extent) for identifying a groove arrangement that minimizes the wear. The wear tests on the grooved bearings were conducted after suitable running-in of the new bearings on a fully automated journal bearing test set-up. A load and speed combination required to operate the bearing in mixed lubrication was used. The performance of different arrangement of bearing was evaluated by measuring their weight loss after the test. Findings Wear was significantly reduced with the use of proper groove arrangement for a bearing operating in mixed lubrication regime. Originality/value The improvement in bearing performance by providing grooves has been the subject matter of several studies in the past, but these studies were confined to the hydrodynamic operative regime of the bearing. In the present work, seven different combinations of axial and radial groove arrangement were tried, which has not been reported in any other work.

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