液氮低温切削钛合金Ti-5Al-5V-5Mo-3Cr刀具失效界限和加工特性研究

项目名称： 液氮低温切削钛合金Ti-5Al-5V-5Mo-3Cr刀具失效界限和加工特性研究

项目编号： No.51475126

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 机械、仪表工业

项目作者： 刘二亮

作者单位： 哈尔滨理工大学

项目金额： 85万元

中文摘要： 航空用钛合金Ti-5Al-5V-5Mo-3Cr（Ti-5553）是近β相亚稳态高强度、高韧性和高硬度钛合金，切削加工性极差。同时，在液氮低温切削时陡峭的工件表面温度梯度，会加剧加工表面缺陷的形核与破坏，降低已加工表面质量。针对上述技术难题，本项目进行低温切削Ti-5553时液氮渗入切削区毛细管润滑和液-汽相变冷却行为研究，建立切屑-刀具-工件间的摩擦模型；基于化学匹配性和摩擦模型，进行刀具磨损演变机制研究，建立低温切削刀具失效界限；分析切屑形态、液-汽相变和刀具磨损演变对动态切削力影响规律，构建切削稳定性预报模型，提出低温切削过程稳定性评价标准；进行表层微观结构演变机制和表面缺陷映射关系的研究，建立基于切削稳定性评价的低温切削条件-表层微观结构-表面缺陷关系描述模型，为优化液氮低温切削工艺条件，实现Ti-5553的低温高效切削提供系统的理论支持。

中文关键词： 钛合金；低温切削；刀具失效界限；切削稳定性；表面缺陷

英文摘要： Near-beta metastable titanium alloys like Ti-5Al-5V-5Mo-3Cr (Ti-5553) are increasingly used in aeronautics in some critical applications. However, Ti-5553 has a poor machinability rating due to its high strength, high toughness and high hardness. In cryogenic(liquid nitrogen) cutting Ti-5553 operations, the issues focus on severe tool wear, cutting instability and surface defects due to the large thermal gradient. Accordingly, the aim of this study is to understand the boundary of tool failure and the characteristics of cryogenic(liquid nitrogen) cutting Ti-5553. The research work is shown as following in detail: (i) According to the analysis of the process of liquid nitrogen penetrating capillary in cutting zone and the cooling effect of liquid-vapor phase change,investigation of friction model at the chip-tool-workpiece interface in cryogenic cutting Ti-5553 process. (ii) Influence of cryogenic cooling on the evolution mechanism of tooe wear and the boundary of tool failure when considering the friction model and the chemical performance match between cutting tools and Ti-5553. (iii) Considering the effect of the chip and liquid-vapor phase change and tool wear on dynamic cutting force, construction of model of cutting stability and determination of the limits of stability in cryogenic cutting Ti-5553 operations with presence of boundary of tool failure. (iv) Investigation of the relationship between the micro-structure of subsurface and surface defects in cryogenic cutting of Ti-5553, construction of the model among the cryogenic cutting conditons and the micro-structure of subsurface and surface defects based on the evaluation of cutting stability. The results of above research work will provide systematic theoretical support in the field of optimizing process planning in cryogenic cutting and high performance machining Ti-5553.

英文关键词： Titanium;Cryogenic cutting;Boundary of tool failure;Cutting stability;Surface defects