Numerical study of microstructural effects on chip formation in high speed cutting of ductile iron with discrete element method
Numerical study of microstructural effects on chip formation in high speed cutting of ductile iron with discrete element method
复制标题
球墨铸铁高速切削微观组织对切屑形成影响的离散元数值研究
DOI：
10.1016/j.jmatprotec.2017.06.006
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发表时间：
2017-11
影响因子：
6.3
通讯作者：
Zhao Wanhua
中科院分区：
文献类型：
--
作者：
He Yong;Zhang Jun;Qi Yutong;Liu Hongguang;Memon Afaque R;Zhao Wanhua
金属切削过程中，微观组织的变形和断裂过程对切屑的形成和加工表面质量有重要影响。本文采用离散元法建立了非均质材料切削模拟模型，以了解切削过程中的微观组织变形和断裂行为。以一种典型的非均质工程材料--ISO450 - 10球墨铸铁为研究对象，进行了模拟和实验研究.分别对石墨球和铁素体晶粒进行了模拟，研究了它们的变形行为。通过仿真得到的切削力和切屑形貌与实验结果进行了比较。光学显微镜和扫描电镜观察表明，切屑自由表面形成了片层结构和不等节段结构。石墨球的变形程度远高于铁素体晶粒的变形程度。此外，随着切削速度的增加，容易产生裂纹，切屑尺寸变小。研究了前刀面附近材料的速度场和应力分布，并进一步讨论了应力与切削速度的关系。非均质模型中离散颗粒的速度波动比均质模型中的更为明显。此外，随着切削速度的增加，材料的应力会发生显著变化，因为可能会出现速度涡，从而导致断裂的发生。结果表明，在高切削速度下，显微组织对裂纹萌生和切屑形成的影响更为显著。
Microstructural deformation and fracture process is important for chip formation and finished surface quality during metal cutting. In this paper, discrete element method (DEM) is introduced to establish a heterogeneous material model for cutting simulation to understand the microstructural deformation and fracture behaviors. A typical heterogeneous engineering material, ISO 450-10 ductile iron, was selected for modeling and experiments. Graphite nodules and ferrite grains were modeled respectively for studying their deformation behaviors. Cutting force and chip morphology obtained by simulation were compared with the experimental results. It shows that lamellar structure and unequal segments form at the chip free surface, which was also observed by optical microscope (OM) and scanning electron microscopy (SEM). The deformed degree of graphite nodules is much higher than that of ferrite grains. In addition, cracks are prone to produce and the chip size becomes smaller as the cutting speed increases. The velocity field and stress distribution of material near the rake face were investigated and the relationship between stress and cutting speed was further discussed. The velocity fluctuation of discrete particles in heterogeneous model is more obvious due to the microstructures compared with that in homogeneous model. Furthermore, the stress of material changes significantly with the increase of cutting speed since velocity vortexes may occur, resulting in the occurrence of the fracture. The results demonstrate that the influences of microstructure on crack initiation and chip formation are more significant at high cutting speeds.
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DOI：
10.1016/s0007-8506(07)60375-8
发表时间：
2006
期刊：
CIRP Annals
影响因子：
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作者：
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影响因子：
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作者：
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影响因子：
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DOI：
10.1016/j.ijmachtools.2011.12.003
发表时间：
2012-03
影响因子：
14
作者：
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