单晶铜在不同温度下的纳米切削机理研究  

Nano-cutting Mechanism of Single Crystal Copper at Different Temperature

作　　者：张彭 李新建 张健生 张毅[1] 黄小光[1] 叶贵根[1] ZHANG Peng;LI Xin-jian;ZHANG Jian-sheng;ZHANG Yi;HUANG Xiao-guang;YE Gui-gen(College of Pipeline and Civil Engineering College of Pipeline and Civil Engineering(East China),China University of Petroleum,Shandong Qingdao 266580,China)

机构地区：[1]中国石油大学(华东)储运与建筑工程学院,山东青岛266580

出　　处：《表面技术》2023年第9期265-277,共13页Surface Technology

基　　金：国家自然科学基金(11972376);山东省自然科学基金(ZR2019MA007);中央高校基本科研专项(22CX03014A)。

摘　　要：目的虽然纳米切削是21世纪超精密加工技术的重要发展方向之一,但现有的纳米切削机理仍不完善。因此,采用数值模拟方法,从晶体结构、力学和粒子运动等方面对纳米切削机理进行补全。方法首先,基于分子动力学方法对纳米尺度下的单晶铜进行了拉伸模拟,总结其在不同温度下的韧脆性特征;其次,对纳米尺度下的单晶铜进行了切削模拟,系统性地研究了切削过程中晶体结构、切削力、应力应变分布,以及原子运动特征在不同材料韧脆性下的变化规律。结果拉伸模拟结果表明,低温下单晶铜脆性特征显著,但仍具有一定的韧性。随着温度的升高,单晶铜脆性减弱,韧性增强。切削模拟结果表明,靠近工件自由面的材料沿主剪切方向发生持续的剪切滑移和周期性的长距离错动,形成多种晶体结构有序分布的块状切屑。靠近刀具的材料在推挤作用下由晶体结构变为非晶结构,之后持续流动形成切屑。随着切削温度的升高,块状切屑中的长距离错动频率提高,通过剪切形成的块状切屑尺寸减小,而通过推挤形成的流动状切屑厚度增加。结论切屑的形成方式包括剪切和推挤2种类型。低温下,剪切切屑形成过程占据主导地位,切屑呈现明显的块状。随着温度升高,切屑形成机理从剪切向推挤转变。Nano-cutting is one of the most important development directions of ultra-precision machining technology in the 21st century.However,the existing nano-cutting mechanism is still not perfect,which restricts the development of this advanced manufacturing technology.The formation and flow evolution of nanochips are the most basic process of nanocutting and the core problem of nano-cutting mechanism research.Firstly,the mechanical properties of single crystal copper in nano-tensile process were studied based on molecular dynamics method.The tensile curves,crystal structure changes and ductile and brittle characteristics at different temperature were analyzed.In the tensile curve,it was found that the curve could be divided into elastic stage and plastic stage.At low temperature,there was a great stress drop phenomenon between elastic stage and plastic stage of the curve.Moreover,the fracture process of metal bond on the surface of single crystal copper crystal was very rapid.The results indicated that the material had brittleness characteristics at low temperature.With the increase of temperature,the phenomenon of stress drop disappeared gradually,and the boundary between elastic stage and plastic stage was no longer obvious.The fracture process of single crystal copper crystal was gradual and slow.The results showed that the material had toughness characteristics.Then,the cutting simulation was studied based on molecular dynamics method and the crystal structure,cutting force,stress-strain distribution and atomic motion characteristics were systematically investigated with the change of material toughness and brittleness.The results indicated that the chip was formed through two ways,namely,the shear and extrusion.The workpiece material near the free surface had shear slip and periodic long distance slippage along the primary shear direction,forming block chips with orderly distribution of different crystal structures.The workpiece material near the tool was destroyed by the extrusion of the tool,the stagnation zone

关 键 词：纳米切削 切屑形成机理 分子动力学模拟 单晶铜 不同温度条件 

分 类 号：TP391.9[自动化与计算机技术—计算机应用技术]