含钛/无钛硬质合金刀具切削钛合金热磨损精准计算的变质量热力学基础理论研究

Carbide tools are widely used in machining titanium alloy. However, there is a contradiction between practice and theory on the applicability of tools with Ti in machining titanium alloys. Thus, it needs to be further studied. Since thermal wear is the main wear mode of both tools with and without Ti in cutting titanium alloys, its process is to be investigated. In order to predict the thermal wear process accurately, it is necessary to determine both wear mode and quantitative studies on physical and chemical process. To get the inherent mechanism of the thermal wear, a variable mass thermodynamic theory of tool wear is put forward, which synthesized thermodynamics of reactions, reaction kinetics, etc. Adhere, diffusion and chemical reaction wear, besides their interaction effect, are calculated by the quantitative thermal wear model based on this method. Three titanium alloys alpha, beta and alpha-beta will be selected to machining to give a clear explanation for the essential cause and fundamental drive of mass migration. The exact thermal wear calculation theory makes itself a qualitative leap in the tool wear study. The anticipated results not only would give a scientific explanation for the the applicability of tools with Ti in machining titanium alloys, but also would promote the basic theory in machining technology. The origin of the thermal wear, including adhere, diffusion and chemical reaction wear, is also revealed. Furthermore, the study is of high engineering application value in machining aerospace difficult-to-cut materials.

目前工业界普遍采用硬质合金刀具加工钛合金，但含钛硬质合金刀具是否适合切削钛合金在理论与实践上存在很大的矛盾，对此迄今尚缺乏有说服力的解释。基于此，本课题将对含钛与无钛硬质合金刀具分别进行考查，从两类刀具切削钛合金的内在磨损机理出发，在对磨损进行定性判断的基础上，重点从定量的角度描述磨损的物理化学过程。方法上，将综合反应热力学、反应动力学等理论提出基于变质量热力学的刀具磨损研究理论，建立定量的硬质合金刀具磨损计算模型，动态描述刀具粘结、扩散、化学磨损过程及其交互作用机理。选用α、β、α+β三种钛合金为被切削对象，阐释刀具磨损阶段质量迁移的本质原因和根本动力，实现刀具磨损研究由定性描述到定量精确计算的质的飞跃。预期成果不仅对含钛硬质合金刀具是否适合切削钛合金作出科学解释，还可以推动切削基本理论的发展，揭示粘结、化学、扩散等热磨损的本质，并使这一理论在航空航天难加工材料切削领域更具工程应用价值。

目前工业界普遍采用硬质合金刀具加工钛合金，但含钛硬质合金刀具是否适合切削钛合金在理论与实践上存在很大的矛盾，对此迄今尚缺乏有说服力的解释。基于此，本课题针对硬质合金刀具切削钛合金刀具的内在磨损机理开展深入研究，在对磨损进行定性判断的基础上，重点从定量的角度描述磨损的物理化学过程。对钛合金切削仿真的基础模型——本构模型，针对高温切削特点建立了更为适用的热力学本构方程。对热磨损中粘接磨损、扩散磨损和化学磨损的机理开展了研究，并利用分子动力学理论研究了钛合金切削反应的动力学过程。定量研究了月牙洼磨损演变过程，实现了月牙洼磨损相关量的快速预测，预测误差在25%以内，修正后将有望控制在10%以内。同时建立了切削钛合金时硬质合金刀具的磨损模型，对切削中刀具磨损形貌的三维演化过程进行了考察，实现了钛合金磨损的精准预测和动态仿真，提出了基于广义磨损量的刀具磨损评价方法及理论。重新定义了切削加工中的扩散磨损过程，对温度场应力场对扩散磨损的作用机制进一步进行了研究，积累了部分关键数据。上述研究不仅对切削钛合金的磨损过程作出科学精确的解释，还可以进一步揭示粘结、化学、扩散等热磨损的本质，并使这一理论在航空航天难加工材料切削领域更具工程应用价值。