微型涡轮叶片五轴微细铣削刀具-工件动态接触特性与加工稳定性研究

Micro turbine which is the key and important component of micro engine, is widely used in aviation, aerospace, ordnance industry, biomedical, and other important fields. The machining of blade is very important and difficult in the machining process of micro turbine. Five-axis micro-milling technology is an effective method to realize the machining of micro turbine blades. This project focuses on the problems which occur in the five-axis micro milling process, such as continuous changing cutter-workpiece engagement geometry, nonlinear milling force affected by multiple factors, complex and dynamic machining stability, and so on. The dynamic evolution rule of cutter-workpiece engagement characteristics, nonlinear mapping relationship between the micro-milling force and its multiple factors, the mechanism of cutting vibration instability and the changing tendency of machining stability which exist in the five-axis micro milling process of micro turbine blades are illuminated. The method for extracting cutter-workpiece engagement geometry is proposed. The five axis micro-milling force model which takes inclination angle, minimum cutting thickness, tool run out, rounded cutting edge radius and process damping into consideration is constructed, and the method for predicting the stability of five-axis micro milling process is also proposed, in order to obtain breakthroughs about the research problems which caused by additional degree of freedom and size effect in the five-axis micro milling process for micro turbine blades. The research of this project will provide theoretical basis and technical support for the five-axis micro milling process of micro complex curved surface.

微型涡轮作为微型发动机的关键核心零部件，广泛应用于航空、航天、兵器、生物医疗等重要领域；叶片的加工是微型涡轮加工过程中的重点和难点，五轴微细铣削技术是实现微型涡轮叶片加工的有效方式。本项目围绕微型涡轮叶片五轴微细铣削过程中多变的刀具-工件动态接触几何、多因素影响下的非线性铣削力、复杂的动态加工稳定性等研究难题，阐明微型涡轮叶片五轴微细铣削过程中刀具-工件接触特性的动态演变规律、微细铣削力与多影响因素之间的非线性映射关系和切削振动的失稳机制与稳定性变化趋势；提出五轴微细铣削刀具-工件接触几何的提取方法，建立综合考虑刀轴倾角、最小切除厚度、刀具跳动、切削刃钝圆半径和过程阻尼效应的五轴微细铣削力模型，提出五轴微细铣削稳定性预测方法，突破微型涡轮叶片五轴微细铣削过程中由于自由度增加和尺寸效应引起的研究难题。本项目的研究将为微小复杂曲面的五轴微细铣削加工提供理论基础和技术支撑。

涡轮叶片的加工质量对微型涡轮，乃至整个微型发动机的机械性能和使用性能都有着重要影响，因而对其制造技术提出了迫切、严苛的要求，开展相应研究势在必行。本项目针对微型涡轮叶片五轴微细铣削过程中多变的刀具-工件动态接触几何、多因素影响下的非线性铣削力、复杂的动态加工稳定性展开研究，形成了适用于微型涡轮叶片五轴微细铣削加工的相关理论和方法。1. 建立了微型涡轮叶片五轴微细铣削过程中刀具位置参数、刀具轮廓参数、刀轴倾角之间的映射关系，基于实体建模法提取了五轴微细铣削过程中不同刀位点的刀具-工件动态接触几何特征；2. 建立了综合考虑刀轴倾角、刀具跳动、切削刃钝圆半径的五轴微细铣削未变形切屑厚度模型，并据此提出了五轴微细铣削切削力模型；3. 综合锤击试验和导纳耦合方法获取微细刀具刀尖点的频率响应函数，提出了适用于铣削稳定性预测的高阶半离散法和组合高阶全离散法，对比分析了所提出方法的预测精度和计算效率。本研究将为微小复杂曲面零件的五轴微细铣削加工提供理论基础和技术支撑。