Modeling and simulation of the high-speed milling of hardened steel SKD11 (62 HRC) based on SHPB technology
Modeling and simulation of the high-speed milling of hardened steel SKD11 (62 HRC) based on SHPB technology
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DOI：
10.1016/j.ijmachtools.2016.05.005
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发表时间：
2016-09
影响因子：
14
通讯作者：
Chengyong Wang;F. Ding;D. Tang;Lijuan Zheng;Suyang Li;Yingxing Xie
中科院分区：
文献类型：
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作者：
Chengyong Wang;F. Ding;D. Tang;Lijuan Zheng;Suyang Li;Yingxing Xie
易切屑是淬硬钢高速铣削的主要特点。在以前的工作中，提出了一个理论几何模型的切屑的形成，以预测切屑形成过程中的剪切带中的应变和应变速率，这些属性是很重要的，当描述的变形特性的切削硬化钢材料。然而，在切削过程中，应力和应变的变化和分布很难通过理论模型得到。利用分离式Hopkinson压杆技术获得的高温高应变率下的应力-应变曲线，考虑材料的负应变率效应和温度效应，对传统的经验Johnson-Cook本构方程进行了修正，特别是针对SKD 11（62 HRC）淬硬钢。采用修正的Johnson-Cook本构方程，建立了SKD 11淬硬钢高速铣削过程的二维热力耦合平面应变有限元模型。预测了SKD 11高速铣削过程中切屑形成的几何特征，预测结果与实验结果吻合较好。采用修正后的有限元模型，对高速切削过程中剪切带的应力和应变进行了定量分析，结果与理论模型分析结果吻合较好。研究发现，切削速度存在一个临界值，在该临界值处，应力和应变达到一定值，剪切带内的应力和应变分布发生变化，导致切屑的产生。此外，切削力，切削温度，涂层刀具的选择进行了讨论，根据与修改后的有限元模型得到的结果。随着切削速度的增加，切削力和温差减小，而温度增加。与TiAlN涂层刀具相比，TiSiN涂层刀具在切削SKD 11淬硬钢时的切削温度更高。
An easy-to-produce sawtooth chip is the main feature of the high-speed milling of hardened steel. In previous works, a theoretical geometric model was proposed for the sawtooth chip formation to predict the strain and strain rate in the shear band during chip formation; these properties are important when describing the deformation characteristics for the cutting of hardened steel materials. In the cutting process, however, the changes and distributions of stress and strain can hardly be obtained using a theoretical model. This paper modifies the conventional empirical Johnson–Cook constitutive equation by employing stress–strain curves at high temperature and a high strain rate obtained using split Hopkinson pressure bar technology and considering the negative strain rate effect and temperature effect of the material, especially for SKD11 (62 HRC) hardened steel. A thermo-mechanical coupled two-dimensional planar strain finite element model for the high-speed milling of SKD11 hardened steel with a modified Johnson–Cook constitutive equation is presented. The geometric characteristics of chip formation during the high-speed milling of SKD11 are predicted and the results are in good agreement with experimental results. Employing the modified finite element model, the stress and strain in the shear band during high-speed cutting are quantitatively analyzed and found to be in close agreement with the results of a theoretical model analysis. It is found that the cutting speed has a critical value at which the stress and strain reach a certain value and the distributions of stress and strain change in the shear band, resulting in the generation of a sawtooth chip. Moreover, the cutting force, cutting temperature, and selection of a coated tool are discussed according to results obtained with the modified finite element model. The cutting force and difference in temperature decrease while the temperature increases as the cutting speed increases. Compared with a TiAlN-coated tool, a TiSiN-coated tool performs better in cutting SKD11 hardened steel in terms of the cutting temperature.