Engineering Faculty Internship: Modeling of the Two-Dimensional Chip Breaking Process for Maching with a Grooved Tool Insert

本文提出的工作是建立一种新的切削力模型，用于传统槽形刀具的切削断屑。这预计将完成使用最近建立的力模型加工与平面（非切屑成形）的工具。拟议的工作将涉及在需要考虑芯片自由端以及芯片槽后壁附加力的条件下，对芯片破碎过程进行分析建模。假设在切屑/刀具后壁和切屑/工作面接触点处存在可变摩擦条件。众所周知的金属切削的剪切面理论将被扩展到包括上述附加摩擦力的影响。实验工作将包括使用高速摄像系统来研究在典型的切屑破碎周期内不同的切屑卷曲和破碎模式，同时使用三组件工具测力计系统连续监测切削力的变化。在分析仿真和实验研究的基础上，提出了采用连续变化载荷的有限元建模技术对卷曲切屑进行建模的方法。机械性能的变化，如通常有助于切屑断裂过程的拉伸应变，将被估计。本工作的主要目的是建立影响晶片破碎的最重要因素，并根据新发现制定新的晶片可破碎性标准。希望在这个项目中预期的新发现将有助于刀具制造商设计新的和创新的切屑成形刀具刀片。

This proposed work is to develop a new cutting force model for chip breaking in machining with a conventional grooved tool insert. This is expected to be accomplished using a recently established force model for machining with a flat-faced (non-chip forming) tool. The proposed work will involve analytical modeling of the process of chip breaking process for conditions requiring consideration of additional forces at the free-end of the chip as well as at the back-wall of the chip groove. Variable frictional conditions will be assumed at the chip/tool back-wall and chip/work surface contact points. The well known shear plane theory of metal cutting will be extended to include the effects of the above additional friction forces. Experimental work will include the use of a high speed filming camera system to study the varying chip curling and breaking patterns within a typical chip breaking cycle while continuously monitoring the cutting force variations with the use of a three-component tool dynamometer system. Based on the analytical simulations and the experimental work, it is expected to model the curled chip using the finite element modeling technique for continuously varying chip loading. The variation of mechanical properties such as the tensile strain which normally contribute to the chip breaking process will be estimated. The major objective of this work is to establish the most significant factors that influence chip breaking and to develop a new chip breakability criterion based on the new findings. It is hoped that the new findings anticipated in this project will help cutting tool manufacturers in designing new and innovative chip forming tool inserts.