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数控铣削加工过程稳定性分析与预测
Stability Analysis and Prediction in NC Milling Processing
【作者】 王军；
【导师】 吴波；
【作者基本信息】 华中科技大学 ， 机械电子工程， 2013， 硕士
【摘要】 在高速高精加工过程中，切削振动尤其是颤振不仅严重降低了加工质量，而且制约着切削效率的提高。对颤振进行分析与预测是保证切削过程平稳进行、提高加工性能的关键前提。目前，判别机床是否发生颤振的主要方法是通过稳定性叶瓣图进行描述。本文以铣削加工稳定性叶瓣图的解析预测方法为基础，以数控铣床主轴-刀柄-刀具系统刀尖点频响函数为对象，呈现了基于柔度耦合子结构分析方法（Receptance CouplingSubstructure Analysis, RCSA）的刀尖点频响函数预测方法，并对铣削加工稳定性进行了分析研究。将机床主轴-刀柄-刀具系统分解为机床主轴-刀柄子结构和刀具子结构两部分，分别进行建模求解。基于Euler-Bernoulli梁模态分析理论，计算刀具末端原点和跨点频响函数；结合有限元模态分析方法，分析Euler-Bernoulli梁理论求解的准确性；通过锤击实验方法和有限差分法得到机床主轴-刀柄子结构末端频响函数；基于RCSA方法，利用线性弹簧和阻尼、扭转弹簧和阻尼来模拟刀柄-刀具结合面间的耦合特性，得到铣削加工系统刀尖点频响函数的半解析预测表达式。以XHK5140数控铣床的加工系统为研究对象，利用锤击实验方法获取机床主轴-刀柄末端以及加工系统刀尖点的频响函数；以刀柄-刀具结合面参数为优化设计变量，应用MATLAB遗传算法优化工具箱（GAOT）对结合面参数进行优化识别；并通过实验研究，分析验证了基于RCSA的刀尖点频响函数预测结果的准确性。以单自由度正交切削加工动力学模型为例阐述了再生型颤振机理；系统分析了Altintas提出的铣削加工稳定性叶瓣图的解析预测方法，并用MATLAB软件编写了绘制稳定性叶瓣图的程序；通过实验研究，分析了应用RCSA预测方法来预测铣削加工过程稳定性的准确性，研究了刀具尺寸参数对加工稳定性的影响。本文的研究为预测数控铣削加工过程稳定性、选择无颤振主轴转速和轴向切深提供了系统的分析方案，具有一定的理论意义和实际应用价值。
【Abstract】 The cutting vibration especially self-excited chatter vibration results in poor processingquality and reduces the cutting efficiency in high-speed precision machining. In order toobtain chatter-free cutting process and high productivity, chatter vibration should be analyzedand predicted. At present, stability lobes diagram is a main method to determine whether thechatter occurs. In this dissertation, based on Receptance Coupling Substructure Analysis(RCSA) and analytical prediction method of stability lobes diagram in milling, the tool pointFrequency Response Function (FRF) is predicted and NC milling stability is analyzed.Machine-spindle-holder-tool assembly is divided into two parts: machine-spindle-holderand the tool. The tool substructure receptances are modeled based on the Euler-Bernoullibeam theory, while the machine-spindle-holder substructure receptances are measured usingimpact testing and finite difference method. The tool and machine-spindle-holder substructurereceptances are coupled through translational and rotational springs and dampers. And thetool point FRF is predicted based on RCSA.The machine-spindle-holder substructure receptances and the assembly tool pointreceptances are obtained by impact testing on the XHK5140milling assembly. The jointparameters between the two substructures are identified by Genetic Algorithm OptimizationToolbox (GAOT) in MATLAB. Experimental validation is provided.The orthogonal cutting system like tuning is presented to explain the fundamentalmechanism of regeneration of chip thickness. The stability lobes diagram in milling ispresented based on analytical prediction by Altintas and drawn using MATLAB software. Andthe effect of the varying tool lengths and diameters on the milling stability is analyzed.The achievements of this dissertation provide an effective approach to predict millingprocessing stability and provide chatter-free cutting speeds and cutting depths, which isproved to have both theoretical significance and practical application value.