基于变转速工作模态分析的高速铣削稳定性预测方法研究

Cutting stability is an important element influencing surface quality and efficiency of high speed machining. Gyroscopic effect, thermal effect and centrifugal force induced by high-speed rotation of spindle change the dynamics of cutting system, which leads to the speed-dependence of tool tip modal parameters and cutting force coefficients. The most current studies consider the dynamics of static or constant speed situation resulting in the inaccurate predication of cutting stability. Therefore, a new approach using modal parameters and cutting force coefficients based on speed-varying operational modal analysis is proposed in this project to get more accurate high speed milling stability prediction. There are three research issues as follows. (1) Time-varying operational modal analysis under non-white noise excitation are developed to identify the speed-varying tool tip modal parameters. (2) Based on the speed-varying modal parameters, compensation method of cutting force is proposed to identify the speed-varying cutting force coefficients. (3) Based on the speed-varying modal parameters and cutting force coefficients, a speed-dependent stability predication method is proposed to calculate the accurate cutting stability lobe diagram, which will be validated through experiment. This research will lay the foundation for cutting parameters optimization and processing efficiency improvement.

切削稳定性是影响高速切削加工质量和效率的重要因素。主轴高速旋转引入的陀螺效应、热效应和离心力等会改变切削系统的动力学特性，使刀尖频响函数和切削力系数产生转速依赖性。目前的研究大多考虑静态或恒定转速下的动力学特性，导致切削稳定性的预测产生较大的误差。为此，本项目以高速铣削加工为背景，提出一种基于变转速工作模态分析，准确预测切削稳定性的方法。研究内容包括：（1）建立非白噪声激励下的时变工作模态分析方法，辨识变转速切削下刀尖的模态参数；（2）基于变转速下的模态参数，建立瞬态切削力补偿方法，辨识变转速切削力系数；（3）基于变转速刀尖模态参数和切削力系数，建立变参数下的稳定域预测方法，由铣削动力学模型，实现高速铣削稳定域的精确预测及实验验证。该方法将为切削参数的优化和加工效率的提升奠定基础。

切削稳定性是影响切削加工质量和效率的重要因素，如何更加准确的判断切削过程的稳定性，对加工过程中的振动因素进行溯源和控制，对完成高质量表面的加工有着重要的意义。本课题旨在通过加工状态下机床结构模态更准确的辨识方法，以及在工作状态下对切削稳定性更加精确的计算，分析加工过程的切削稳定域，确定影响加工质量的核心因素。项目建立了工作状态下基于振动响应信号的非白噪声工作模态辨识方法，发展了基于振动信号的切削颤振状态辨识方法，改进了高阶全离散算法，对薄壁件切削过程的稳定性进行了分析及验证；拓展建立了基于工作振动模态分析及信号时频分析，结合加工表面形貌测量分析的加工表面振动溯源方法。项目建立了完整的分析理论和算法流程，为切削质量的提升提供了理论支持和技术基础。