Abstract

An accurate prediction of cutting force is significant, as it plays a critical role on surface quality and tool wear. In micro-endmilling, the machined feature size and feed/tooth are comparable to the material grain size and the edge radius of the endmill. Hence, the effects of scaling issues, material micro-structure and cutting temperature on the machining performance need to be addressed. This article presents a force model for micro-endmilling by incorporating size effect, machining temperature, workpiece spring back effect and micro-structure evolution. The developed force model was validated with experimental results on Inconel 718 and the prediction error was found to be less than 10%. An experimental study to understand the influence of size effect on cutting force, micro-hardness and surface defect during micro-endmilling on Inconel 718 was carried out. Minimum uncut chip thickness was observed adjacent to 0.9 µm. For a feed/tooth less than 0.9 µm, both cutting force and micro-hardness of the endmilled surface shows a nonlinear trend. Higher value of cutting force at feed/tooth less than 0.9 µm was observed due to high strain hardening, and significant plowing effect on the micro-endmilled surfaces.

摘要

准确预测切削力非常重要，因为它对表面质量和刀具磨损起着至关重要的作用。在微立铣削中，加工特征尺寸和进给/齿与立铣刀的材料粒度和刃口半径相当。因此，需要解决结垢问题、材料微观结构和切削温度对加工性能的影响。本文通过结合尺寸效应、加工温度、工件回弹效应和微观结构演变，提出了微端铣的力模型。开发的力模型通过 Inconel 718 的实验结果进行了验证，发现预测误差小于 10%。了解尺寸效应对切削力影响的实验研究，在 Inconel 718 上进行微端铣削过程中的显微硬度和表面缺陷。在 0.9 µm 附近观察到最小未切屑厚度。对于小于 0.9 µm 的进给/齿，铣削表面的切削力和显微硬度均呈现非线性趋势。由于高应变硬化和对微立铣表面的显着犁削效应，在进给/齿小于 0.9 µm 处观察到更高的切削力值。