硬旋铣加工刀具刃口非均匀钝化延寿机理及精准设计方法研究

Hard whirling is an efficient and green high speed hard dry cutting technology, and has broad application prospects. But the hard whirling has the characteristics of time varying and interrupted cutting, the cutting edge load distribution is non-uniform, which makes the edge easy to produce partial damage, and the tool life is short. It becomes one of the bottleneck problems that restrict the comprehensive performance of hard whirling. In this project, aims at the time varying and non-uniform load characteristics, the new non-uniform cutting edge preparation idea for life extension is proposed. The mechanism and design basis of non-uniform cutting edge is also studied. The contact form of cutting tool with non-uniform cutting edge and chip is studied, and the mapping relationship between edge parameters and friction characteristics is established. Based on variable friction factor finite element method, the mechanism of non-uniform cutting edge is researched. The load distribution rules on cutting edge of the hard whirling are studied, and the thermodynamic behavior of the deformation zone is analyzed. Based on the stability criterion of excess entropy production, the precision design method of the non-uniform cutting edge is proposed. The relationship between non-uniform cutting edge and surface quality of workpiece is studied, and the life prediction model is established to reveal the evolution law of the tool's performance. This project is expected to reveal failure essence of hard whirling cutting tool from the point of view of thermodynamic stability, implement matching cutting tool edge preparation, and provide theoretical basis and technical support for design of the long-lived hard whirling cutting tools.

硬旋铣是一种高效、绿色的高速硬态干式切削技术，应用前景广阔。但硬旋铣具有时变断续切削特性，切削刀具刃口载荷分布不均，使得刃口易产生局部破损，刀具寿命短，成为制约其综合性能提升的瓶颈问题之一。本项目针对硬旋铣加工刀具刃口时变非均匀受载的特点，提出刃口非均匀钝化的延寿新思路，开展刀具非均匀钝化刃口作用机理及设计基础研究。研究刃口非均匀钝化刀具的刀-屑接触形态，建立刃口参数与刀-屑摩擦特性之间的映射关系，基于变摩擦因数有限元分析方法，研究非均匀钝化刃口的作用机理；研究硬旋铣刀具刃口载荷分布规律，分析切削变形区的热力学行为，基于超熵产生稳定性判据，提出非均匀钝化刃口的精准设计方法；研究非均匀钝化刃口与加工表面质量间的关系，建立刀具寿命预测模型，揭示刀具性能演变规律。本项目的研究有望从热力学稳定性角度揭示硬旋铣加工刀具失效本质，实现刀具刃口的适配性钝化，为长寿命硬旋铣刀具设计提供理论基础与技术支撑。

针对硬旋铣加工时切削区存在强应力耦合，应力场分布不均匀，刀具易局部破损，加工质量难以保证的问题，提出刀具刃口非均匀钝化的延寿新思路。项目从刀具刃口统一评价标准入手，通过研究刃口非均匀钝化刀具在加工过程中的刀-屑接触特性及摩擦学行为规律，揭示非均匀钝化刃口作用机理；研究了硬旋铣加工刀具钝化刃口热力学行为，建立非均匀钝化刃口的优化设计方法，实现面向精密滚珠丝杠硬旋铣刀具非均匀钝化刃口的精准设计；研究了刃口非均匀钝化刀具切削性能，揭示了刃口非均匀钝化硬旋铣加工刀具的性能演变规律，实现刃口非均匀钝化硬旋铣加工刀具的寿命预测。本项目研究有望优化硬旋铣加工技术，解决刀具刃口非正常局部破损问题，为硬旋铣加工刀具延寿设计提供新途径。主要研究结果有：1.基于曲率差分刀具刃口截面线分界点识别和刀具刃口曲面的分形插值重构方法，为刀具刃口精确建模以及表征提供了便利。包含刃口圆弧半径、刃口曲面分形维数和形状系数的双尺度多指标表征方法，为硬旋铣加工刀具刃口对其切削性能的影响评价提供了统一标准。2.分析了硬旋铣加工的基本原理和运动特点，基于瞬时切削体积等效的原则建立了硬旋铣加工的简化模型，考虑微观特征的刃口切削力模拟结果更准确，与实验值的误差为3.95%。3.在保证刃口强度、避免刃口破损的前提下，选择较小的刃口圆弧半径和倒棱参数组合也会减小切削力和切削温度。一定范围内增加刃口钝化半径可提高刃口强度，刀具早期破损的发生概率降低约60%左右。非均匀钝化刀具的整体抗破损性能突出，为大型滚珠丝杠硬旋铣加工刀具刃口的延寿设计提供了思路。