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Modélisation du film lubrifiant dans la zone d'entrée, pour la lubrification par émulsion en laminage à froid.

Abstract : When using an emulsion as a lubricant, one often observes a speed range with stable working conditions, namely friction remains approximately constant. But at higher speeds in some cases, above a critical speed in the m/s range, accelerating increases friction. As a consequence, the rolling mill cannot reasonably work at higher speed, limiting expected productivity gains. Why does friction increase, and how to avoid it?To answer this question, we try to relate global observations in strip rolling (“average friction”, Reich et al.) and lubricant film thickness measurements by Zhu et al. in a rather different context: Elasto-Hydrodynamics (EHD). Indeed, we consider that the behaviour observed in EHD provides a viable explanation to emulsion behaviour in strip rolling.To confirm this analogy between two sharply different situations, we turned to modelling. It is necessary to analyze the mechanisms which contribute to the formation of the lubricant film in both cases. The literature offers two kinds of diphasic thin lubricant film models: Szeri's and Wilson's. We completed and coupled them, noting that each may represent correctly the conditions prevailing in the diverse parts of the contact. In lubrication, the model developed shows that emulsification-related properties, such as the size of the oil droplets and their capacity to wet the solid surfaces and form a significant "plate – out film", are much more influential than oil-related properties (viscosity).
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Submitted on : Monday, October 22, 2007 - 9:43:54 AM
Last modification on : Thursday, September 24, 2020 - 5:22:54 PM
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  • HAL Id : tel-00180820, version 1

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Stéphane Cassarini. Modélisation du film lubrifiant dans la zone d'entrée, pour la lubrification par émulsion en laminage à froid.. Mécanique [physics.med-ph]. École Nationale Supérieure des Mines de Paris, 2007. Français. ⟨tel-00180820⟩

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