单晶金刚石刀具切削单晶硅时后刀面会发生剧烈沟槽磨损, 严重影响零件加工质量和刀具寿命。为了从金刚石石墨化转变角度揭示沟槽磨损生长扩展机制, 建立了金刚石刀具后刀面具有初始沟槽的分子动力学模型, 模拟了切削单晶硅时初始沟槽处的工件材料流动行为与金刚石刀具晶体结构变化情况。结果表明, 初始沟槽的存在改变了工件材料的流动状态;并且这种材料流动引起了刀具初始沟槽附近温度和能量的变化, 温度升高了8%, 势能提高了1.4%;通过分析金刚石刀具晶体结构发现, 初始沟槽处的刀具材料发生了石墨化转变, 并通过计算采样点处原子间键角, 得到了石墨化转化率随着切削的进行不断升高, 并最终趋于恒定的规律, 当切削进入到稳定切削阶段时, 石墨化转化率约为6%。

The occurrence of the groove wear on the flank face of diamond cutting tool makes a serious impact on the quality of the finish surface of the workpiece. In order to reveal the growth and extension mechanism of the groove wear from the perspective of graphitization, the molecular dynamics (MD) model of diamond cutting tool with initial groove on the flank face is established, and the motion of the workpiece material and the change of crystal structure of the diamond cutting tool are simulated. The results show that the motion of the workpiece material changes for the existence of the initial groove, and the temperature and the energy of the atoms increase in the cutting process, nearly 8% for the temperature and 1.4% for the energy. The analyses of crystal structure and the radial distribution function of the diamond cutting tool show that there is a diamond-graphite transformation on the initial groove. The change of the graphitization conversion with cutting time is studied through bond angle calculation. The graphitization conversion rate increases with cutting time, when the cutting process proceeds to the stable stage, the graphitization conversion rate tends to be stable at nearly 6%.