Analytical modelling of the trans-scale cutting forces in diamond cutting of polycrystalline metals considering material microstructure and size effect
Analytical modelling of the trans-scale cutting forces in diamond cutting of polycrystalline metals considering material microstructure and size effect
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DOI：
10.1016/j.ijmecsci.2021.106575
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发表时间：
2021-06
影响因子：
7.3
通讯作者：
Zhanwen Sun;Tao Zhang;Peizheng Li;Sujuan Wang;S. To;Hailong Wang
中科院分区：
文献类型：
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作者：
Zhanwen Sun;Tao Zhang;Peizheng Li;Sujuan Wang;S. To;Hailong Wang
在金刚石切削多晶金属时，由于未变形切屑厚度（UDCT）从微米级到纳米级的跨尺度变化，尺寸效应和微观结构对切削力的影响尤为突出。本文提出了一种跨尺度的金刚石切削多晶金属的切削力模型，该模型充分考虑了微观结构、材料弹性回复、尺寸效应和圆刃效应。将微成形理论与晶体塑性理论相结合，建立了一种确定主变形区流变应力的混合滑移线模型（HSLM），该模型能够定量地反映尺寸效应和晶粒尺寸、晶界和晶体各向异性等微观结构对流变应力的影响。然后，利用刀-屑接触模型，通过分析刀-屑界面的应力分布和摩擦状态，确定了法向切削力和摩擦切削力。基于压痕理论，确定了在很小的超临界尺寸下材料弹性回复引起的摩擦力。通过金刚石切削不同晶粒尺寸的多晶铜，实验证明，所提出的HSLM能够捕捉到随着尺寸因子的增大，切削机理从剪切（拉应力）向犁削（压应力）转变的现象。此外，与传统的基于Johnson-Cook本构方程的力模型相比，所提出的力模型具有更高的估计精度。
In diamond cutting of polycrystalline metals, the influence of size effect and microstructure on the cutting force is prominent due to the trans-scale variation of undeformed chip thickness (UDCT) from microscale to nanoscale. This study proposes a trans-scale cutting force model for diamond cutting of polycrystalline metals with the full consideration of microstructure, material elastic recovery, size effect and round-tool-edge effect. Specifically, by corelating micro-forming theory and crystal plastic theory, a hybrid slip-line model (HSLM) is developed to determine the flow stress in the primary deformation zone, which can quantify the influence of size effect and microstructure, such as grain size, grain boundary and crystal anisotropy, on flow stress. Then, the normal cutting force and frictional cutting force are determined by analysing the stress distribution and frictional states at tool-chip interface using a tool-chip contact model. The rubbing force induced by material elastic recovery at very small UDCT is determined based on indentation theory. Through diamond cutting of polycrystalline copper with different grain sizes, it is experimentally demonstrated that the proposed HSLM can capture the cutting mechanism transformation phenomenon from shearing (tensile stress) to ploughing (compressive stress) with increasing size factor. Besides, the proposed force model has the improved estimation accuracy compared with the conventional force models developed based on Johnson-Cook constitutive equation.