纳米切削中水的物理作用的分子动力学仿真

Molecular Dynamics Simulation of Physical Effect of Water in Nanometric Cutting

为了减少刀具磨损、提高工件表面完整性,借助分子动力学仿真对金刚石纳米级切削单晶铜进行了深入研究,比较了干切和加水切削时的晶格变形、切削力和热耗散,探讨了水基切削液和断续切削对刀具磨损和表面质量的影响.结果表明:水分子能够有效将刀具表面和被切材料分隔开,但是由于刀尖处接触压力极高、水膜易被穿透致使刀尖与铜原子直接作用,因此黏着现象无法完全避免.加水切削有利于减小摩擦力并降低刀具表面热量,工件已加工表面完整性得到提高,而断续切削有利于水膜的保持并充分发挥其冷却润滑作用.

To reduce tool wear and improve the surface integrity of workpiece, molecular dynamics simulations of water lubrication assisted diamond nanometric cutting of single-crystal copper were conducted. The comparison of lattice deformation, cutting force and heat dissipation between dry and lubricated cutting was made. The effects of water-based lubricant and intermittent cutting on tool wear and surface integrity were discussed. It is found that water molecules can effectively separate the tool surface and the substrate, but direct interaction between tool tip and copper atoms cannot be avoided because of very high contact pressure and easy-to-be-penetrated water film. The simulation illustrates that water lubrication is beneficial for improving the surface integrity of workpiece, reducing friction, and decreasing the heat generation on the tool surface, but the extreme pressure at the tool tip prevents the total elimination of tool wear. Intermittent cutting is beneficial for maintaining water layer.