纳米切削初始温度对单晶铜微观结构的影响

Effect of Initial Temperature of Nano-cutting on Microstructure of Single Crystal Copper

纳米切削会造成工件的内部微观缺陷,这种缺陷会引起残余应力的变化进而影响工件的表面质量,而这种缺陷结构与切削层初始温度有密切联系。为降低工件纳米切削加工制造中的缺陷,采用分子动力学的方法,构建了含有切削层的单晶铜纳米切削模型。首先,通过分析工件结构体积及微观缺陷的变化确定了切削层的适用初始温度;其次,分析了切削层初始温度对切削力的影响,并在不同初始温度和切削力作用下对单晶铜位错和晶格等微观结构的变化进行了分析;最后,通过实验对仿真结果进行了间接验证。结果表明:单晶铜切削层初始温度的可选范围为293~400 K;在此范围内,随着切削层初始温度的升高,切削力大小变化显著,但波动平稳,晶格结构的转变速度也随之增快;当切削层初始温度设在360~390 K范围内时,单晶铜工件的表层微观缺陷相对较少,由此可预测单晶铜工件在此初始温度范围内加工得到的表面质量较高。

Nano-cutting causes internal microscopic defects in the workpiece, and this defect structure is closely related to the initial temperature of the cutting layer. In order to reduce the defects of workpieces in nano-cutting, a nano-cutting model of single-crystal copper with a cutting layer was constructed using molecular dynamics. Firstly, the applicable initial temperature of the cutting layer was determined by analyzing the changes in the structural volume and microscopic defects of the workpiece. Secondly, the effect of the initial temperature of the cutting layer on the cutting forces, dislocations and lattice was analyzed. Finally, the simulation results were indirectly verified by experiments. The results show that the applicable initial temperature range of cutting layer for single crystal copper is 293~400 K. As the initial temperature of the cutting layer increases, the transition rate of the lattice structure increases and the magnitude of the cutting force changes significantly, but the effect on fluctuations is small. When the initial temperature of the cutting layer is set in the range of 360~390 K, the surface microscopic defects of the single crystal copper workpiece are relatively less, and thus it is predicted that the surface quality of the single crystal copper workpiece is higher when it is machined in this initial temperature range.