基于响应耦合法的切削工艺系统动力学研究

发布时间：2018-05-18 04:40

本文选题：高速铣削 + 铣削稳定性　；参考：《天津职业技术师范大学》2015年硕士论文

【摘要】：高速切削由于其加工效率高，切削力小，表面质量高等优点，已广泛应用于航空，汽车以及模具制造等领域。然而在生产过程中，颤振是造成工件表面质量下降，刀具的磨损，甚至机床的损坏的一个主要问题。为了避免颤振，对切削过程的稳定性进行准确预测具有一定的工程意义，这就需要对机床切削系统的动力学特性进行分析。刀尖点频响函数，反应了机床切削系统在刀具端点的动态特性，被用于绘制稳定性叶瓣图，因此它的求取对于机床切削稳定性的预测非常重要。本文以对高速铣削系统稳定性进行预测为目的，深入分析了切削系统的动力学特性和铣削稳定性的求解方法，研究了电主轴的动力学特性，主要工作如下：基于传递矩阵法，在原有的主轴动力学模型的基础上考虑了轴承的阻尼效应，用数学方法建立了电主轴典型单元状态矢量的传递矩阵；利用MATLAB软件编制了相关的计算程序用以分析主轴的固有频率，，主振型，以及响应等动态特性参数。运用响应耦合法(Receptance Coupling Substructure Analysis, RCSA)，在Euler-Bernoulli梁理论的基础上，对机床刀尖点频响函数进行预测。模型将机床分为了三个子结构；利用Euler-Bernoulli梁模型响应求解子结构的响应公式；在子结间建立由线性弹簧、旋转弹簧、线性阻尼和旋转阻尼组成的连接模型，并求解了连接模型中的参数；基于RCSA方法，通过已求取的连接模型，耦合各子结构关键点的传递函数，获得新的机床切削系统刀尖点的频响函数。基于再生型颤振理论，构建铣削动力学模型，利用解析法获得了稳定性叶瓣图。考虑到铣削力系数随主轴转速的变化而改变，提出一个改进的铣削动力学模型。基于全离散时域求解方法，研究了在不同主轴转速时，不同径向浸入比的情况下，轴速相关铣削力系数对铣削稳定性的影响。结果说明在高速铣削过程中，低径向浸入比时考虑轴速相关铣削力系数对铣削稳定性的求解是非常重要的。
[Abstract]:High speed cutting (HSM) has been widely used in aviation, automobile and die manufacturing due to its high efficiency, low cutting force and high surface quality. However, flutter is one of the main problems that cause the surface quality of workpiece, tool wear and even machine tool damage. In order to avoid chatter and predict the stability of cutting process accurately, it is necessary to analyze the dynamic characteristics of machine tool cutting system. The frequency response function of the cutting point reflects the dynamic characteristics of the cutting system at the end of the tool and is used to draw the stable blade diagram, so its calculation is very important for the prediction of the cutting stability of the machine tool. In order to predict the stability of high-speed milling system, the dynamic characteristics of cutting system and the solution of milling stability are deeply analyzed in this paper. The dynamic characteristics of motorized spindle are studied. The main work is as follows: Based on the transfer matrix method, the damping effect of the bearing is considered on the basis of the original spindle dynamic model, and the transfer matrix of the state vector of the typical unit of the motorized spindle is established by mathematical method. Using the MATLAB software, the related calculation program is developed to analyze the dynamic characteristic parameters such as the natural frequency, the main mode and the response of the spindle. Based on the theory of Euler-Bernoulli beam, the response coupling method is used to predict the frequency response function of tool tip. The model divides the machine tool into three substructures: the Euler-Bernoulli beam model is used to solve the response formula of the substructure, and the connection model consisting of linear spring, rotary spring, linear damping and rotational damping is established between the sub-junctions. The parameters in the connection model are solved and the frequency response function of the cutter tip of the new machine tool cutting system is obtained by coupling the transfer function of the key points of each substructure through the obtained connection model based on the RCSA method. Based on the theory of regenerative flutter, the milling dynamics model is constructed, and the stable leaflet diagram is obtained by analytic method. Considering the change of milling force coefficient with the change of spindle speed, an improved milling dynamic model is proposed. Based on the full discrete time domain solution, the effect of axial velocity dependent milling force coefficient on milling stability is studied under different spindle speeds and different radial immersion ratios. The results show that in the process of high speed milling, it is very important to consider the axial velocity correlation milling force coefficient for the solution of milling stability when the radial immersion ratio is low.
【学位授予单位】：天津职业技术师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG54

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