微量润滑磨削界面的分子动力学模拟

Molecular Dynamics Simulation for Grinding Interface Under Minimum Quantity Lubrication

为了研究微量润滑磨削界面的冷却润滑效应,以离子液体作为微量润滑磨削液,对微量润滑磨削界面进行了分子动力学模拟研究。分析了微量润滑磨削界面的热量分配关系,揭示了磨削界面热量的产生与传散机制,研究了磨削过程中磨削力、磨削力比以及磨粒工件之间液膜状态的变化。结果表明:离子液体雾滴在磨削界面的冷却效果显著,工件的热量分配比由干磨时的74.1%减小到微量润滑磨削时的68%~69%;磨削热主要来源于剪切变形区内工件材料发生的晶格变形,其次是磨粒与工件之间的摩擦;磨削热首先在工件基体、磨粒和切屑之间传递,然后经切屑传递给雾滴,雾滴再传递给磨粒;磨削力随未变形切屑厚度的增加而线性增大;当磨粒切入工件形成切削作用时,磨粒-工件界面和磨粒-切屑界面会产生极高的挤压应力,导致难以形成边界润滑膜。

To research the cooling and lubricating effects on the grinding interface under minimum quantity lubrication,a molecular dynamics simulation of grinding interface under minimum quantity lubrication with ionic liquid is performed.The heat partition relationship on the grinding interface is analyzed,and the generation and transfer mechanisms of grinding heat on the grinding interface are revealed.The variations of grinding force,grinding force ratio,and the liquid film between abrasive grain and workpiece are investigated.The results show that the cooling effect of the ionic liquid droplet is outstanding.The heat partition ratio of the workpiece reaches 74.1%in dry grinding,and under minimum quantity lubrication,the heat partition ratio of the workpiece is reduced to 68%-69%.Grinding heat is mainly generated from the lattice deformation of the workpiece material in the shear zone,and the secondary heat source is friction between the abrasive grain and the workpiece.The generated heat is firstly transferred into the workpiece substrate,the abrasive grain,and the grinding chip directly,afterwards,a portion of heat in the grinding chip is transferred into the ionic liquid droplet,then a portion of the heat in the ionic liquid droplet is transferred into the abrasive grain.The grinding force linearly increases with the increasing undeformed chip thickness.As the abrasive grain cutting into the workpiece,highly compressive stress appears on the grain-workpiece and grain-chip interfaces,which leads to difficulty in forming a boundary lubricating film.