金属切屑塑性流动的稳定性

马维

doi:10.6052/0459-1879-17-270

金属切屑塑性流动的稳定性

doi: 10.6052/0459-1879-17-270

马维^*, ,

中国科学院力学研究所流固耦合系统力学重点实验室,北京 100190

基金项目: 国家自然科学基金资助项目(11572337, 51575029, 11772346).

详细信息

作者简介:
*通讯作者：马维,副研究员,主要研究方向：材料动态力学性能,材料工艺力学. E-mail: watwm@imech.ac.cn, 13146247958@163.com

通讯作者:
马维

中图分类号: TG506;
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出版历程
- 收稿日期: 2017-08-04
- 刊出日期: 2018-01-18

STABILITY OF PLASTIC FLOW OF METALLIC CHIPS

Ma Wei^{*
, ,}

Key Laboratory for Mechanics in Fluid Solid Coupling System,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China

摘要

摘要: 对金属正交切削过程中切屑形成机制和材料塑性流动行为进行实验研究和理论分析. 通过对4 种常用金属材料正交切削过程的实验研究和切屑形貌的微观观察,确定了连续切屑转变成锯齿切屑的临界速度. 结果表明该临界速度与材料性能相关. 在实验观察基础上,提出描述材料正交切削过程的二维分析模型. 该模型假设切屑形成区为包括主剪切区和次剪切区的一个平行四边形. 载荷有主剪切区中的剪应力和次剪切区中的正压力;通过量纲分析得到描述材料正交切削过程的无量纲主控参数和无量纲形式的基本控制方程;应用线性稳定性分析方法建立平面应变状态下评价材料塑性流动稳定性的普遍准则;求得切屑形成区内材料塑性变形的速度和应力近似解. 讨论切屑形成、形貌转变以及相关的塑性失稳机制. 分析结果表明, 表征材料惯性与阻尼之比的无量纲参数— 雷诺数可以作为主控参数描述金属切削过程以及切屑材料塑性流动的稳定性.
- 塑性流动稳定性 /
- 失稳判据 /
- 量纲分析 /
- 切屑形貌转变
Abstract: This work deals with the experimental and analytical investigations of the formation mechanisms and the plastic flow stability of chips in the orthogonal cutting processes. In the cutting experiments, four kinds of metal are chosen as modelling materials. In the high-speed cutting process of each testing metal, we observed the transformation of chip morphology from continuous to serrated and determined the critical cutting speed which depends on the material properties of workpiece and the cutting conditions. Based on the experimental results, a two-dimensional orthogonal cutting model is proposed for analyzing the two-dimensional effects of chip flow and a corresponding basic theoretical framework is established under the plane strain loading condition. By introducing a group of scaling quantities that related to the cutting condition parameters, a system of dimensionless governing equations is obtained by normalization, a main dimensionless controlling parameter is determined in terms of experimental conditions and numerical simulation results, an instability criterion is established by the linear perturbation analysis under plane strain loading conditions, and the asymptotic flow fields on the velocity and stress in the extended chip formation zone are obtained by approximate analysis of chip flow. The theoretical results showed that, provided the cutting speed is sufficient high, the plastic flow of continuous chip will be unstable. This instability behavior of chip would be the non-localization unstable flow of the continuous chip caused by plane loadings and differs from the shear-localized instability in the serrated chip. The dimensionless controlling parameter, called as the modified Reynold number, did play a leading role since it better describes the plastic instability behavior of continuous chip flow and the shear-localized instability behavior of the serrated chip in the orthogonal cutting process of metals.
- metal cutting /
- plastic flow stability /
- instability criterion /
- dimensional analysis

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参考文献(1)

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