Analytical modelling of cutting forces in ultra-precision fly grooving considering effects of trans-scale chip thickness variation and material microstructure
Analytical modelling of cutting forces in ultra-precision fly grooving considering effects of trans-scale chip thickness variation and material microstructure
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DOI：
10.1007/s00170-021-08080-5
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发表时间：
2021-10
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影响因子：
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通讯作者：
Zhanwen Sun;S. To;Peizheng Li;Sujuan Wang;Tao Zhang
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作者：
Zhanwen Sun;S. To;Peizheng Li;Sujuan Wang;Tao Zhang
虽然超精密飞槽技术已被广泛应用于微结构表面的加工，但对超精密飞槽切削力模型的研究较少。UPFG独特的运动学特性导致了未变形切屑厚度从纳米尺度到微米尺度的跨尺度变化，其中材料微观结构和尺寸效应的影响尤为突出。本研究综合考虑了超细粉末冶金的运动学、切屑形成机理、材料微观结构、材料弹性回复、尺寸效应和刀具几何形状等因素，建立了超细粉末冶金的切削力解析模型。通过将微观成形理论与晶体塑性理论相结合，建立了确定初始变形区流动应力的混合滑移线模型(HSLM)，该模型可以量化尺寸效应和微观组织(如晶粒度、晶界、位错密度和晶体各向异性)对流动应力的影响。然后通过分析刀具-切屑界面的应力分布和摩擦状态，估算出法向切削力和摩擦切削力。根据压痕理论确定了材料弹性回复产生的摩擦力。最后，通过对不同加工参数下的多晶铜的飞切实验验证了该模型的有效性，并证明了该方法能够捕捉到刀具旋转下超细晶铜超细粉碎过程中从犁削(压应力)到剪切(拉应力)的周期性变化。
Although ultra-precision fly grooving (UPFG) is widely applied to fabricate micro-structured surfaces, few studies have focused on the cutting force model of UPFG. The unique kinematics of UPFG leads to the trans-scale variation of undeformed chip thickness from nanoscale to microscale, in which case the influence of material microstructure and size effect is prominent. This study proposes an analytical cutting force model for UPFG with full consideration of the kinematics, chip formation mechanism, material microstructure, material elastic recovery, size effect, and tool geometry. Specifically, by correlating micro-forming theory to crystal plastic theory, a hybrid slip-line model (HSLM) is developed to determine the flow stress in primary deformation zone, which can quantify the influence of size effect and microstructure, such as grain size, grain boundary, dislocation density, and crystal anisotropy, on flow stress. Then, the normal cutting force and frictional cutting force are estimated by analyzing the stress distribution and frictional states at tool-chip interface. The rubbing force induced by material elastic recovery is determined based on indentation theory. Finally, the models are experimentally validated by fly cutting of polycrystalline copper with different machining parameters, and it is also demonstrated that the proposed HSLM can capture the periodic transformation of cutting mechanism in UPFG from ploughing (compressive stress) to shearing (tensile stress) with tool rotation.