多晶体金属微切削动态过程在位分析

In-situ Analysis of Dynamic Process of Polycrystalline Metal Micro-cutting

在多晶体金属微切削加工中,刀具刃口钝圆半径与切削厚度及晶粒尺寸的数量级相当,相比于宏观切削,刀具的刃口钝圆半径对切削过程中的材料变形、切屑形成以及微结构演化等有显著影响。本文针对多晶体金属材料H70黄铜开展了系列正交微切削试验,通过高速摄像机记录完整的切屑形成过程,进而在位分析材料的塑性变形、微结构演化等,从而更加深入、全面考察金属微切削的本质特征。试验结果表明:H70黄铜在不同切削深度下剪切角的大小基本保持不变,切屑的形状始终为锯齿形切屑;微切削中存在沿晶断裂现象;在切削速度为500μm/s且刀具刃圆半径为10μm时,最小切削厚度在0.5μm以下。

In the micro-cutting of polycrystalline metals,the rounded cutting edge radius of the tool is equivalent to the cutting thickness and grain size in the order of magnitude.Therefore,compared with micro cutting,the rounded cutting edge radius of the tool has a significant impact on the material deformation,chip formation and microstructure evolution during the cutting process.This paper carries out a series of orthogonal micro-cutting experiments for the polycrystalline metal material H70 brass.The complete chip formation process is recorded by a high-speed camera,and then the plastic deformation and microstructure evolution of the material are analyzed on-site,so as to conduct a more in-depth and comprehensive investigation of the essential characteristics of metal micro-cutting.The test results show that the shear angle of H70 brass remains basically unchanged at different cutting depths,and the shape of the chips is always serrated chips;there are intergranular fractures in micro-cutting;when the cutting speed is 500μm/s and the blade radius is 10μm,the minimum cutting thickness is 0.5μm or less.