Usinage des aciers prétraités à l'huile entière : effets physico-chimiques des additifs soufrés

Machining of high strength steel with straight cutting oils - physico-chemical effects of sulphur

• Auteur / Autrice : Aleksandra Bierla
• Direction : Jean-Michel Martin, Guillaume Fromentin, Clotilde Minfray
• Type : Thèse de doctorat
• Discipline(s) : Génie mécanique. Procédés de fabrication
• Date : Soutenance en 2009
• Etablissement(s) : Paris, ENSAM
• Partenaire(s) de recherche : Autre partenaire : Arts et Métiers ParisTech. Centre d'enseignement et de recherche (Cluny)

Mots clés

Mots clés contrôlés

Réactions chimiques -- Mécanismes

Auger, Effet

Usinage

Résumé

De nombreuses opérations d’usinage nécessitent la présence d’un fluide de coupe afin d’en assurer le succès du fait de la sévérité des sollicitations que subit l’outil. Le but de l’étude est d’identifier les performances de divers additifs soufrés dans les huiles entières, de sélectionner parmi eux l’additif soufré le plus efficace pour la coupe des métaux, ainsi que de comprendre leurs mécanismes d’action dans les différentes applications d’usinage. L’objectif de l’étude est donc d’analyser les mécanismes tribochimiques de lubrification mis en jeu dans les procédés d’usinage et d’optimiser la formulation du lubrifiant. L'influence des différents paramètres liés à la coupe est également étudiée afin d'apporter plus de connaissances sur l'action générale des lubrifiants dans le cas de l'usinage moderne.

Most machining operations require the presence of a cutting fluid in order to ensure its success due to the intensity of thermal and mechanical conditions. The objective of this study is to identify and compare the performance of various sulphur additives, select between them the most efficient one, and understand their action mechanisms in the different applications of machining. Thus, this study aims at analyzing the tribochemical mechanisms of lubrication during machining operations and subsequently at optimizing the formulation of the lubricant. The influence of different cutting parameters is also investigated with intention to bring more knowledge about the general action of lubricants in case of modern machining. Firstly, machining tests are performed to measure the effect of the different additives. The goal is to establish the effectiveness of cutting oils according to machining parameters - such as the specific cutting force. The study is completed with the performance evaluation of cutting oils in terms of tool life (or wear). The comparison of additives performances in form tapping is also accomplished by the means of average tapping torque. Secondly, a physicochemical analysis (AES, XPS) is carried out with the purpose of detecting the nature of the additives reaction products with the surface (chips, tools, workpieces). A correlation between the results of additives performance evaluation by the mechanical tests and their surface reaction products is highlighted. Some complementary analyses, such as analysis of thermal behavior of additives (TGAIIR, DSC), observation of thin section of chip by TEM as well as modeling of friction in presence of gaseous sulphur additive in the Environmentally Controlled Tribometer (ECT) are realized.