薄壁多框结构件高效铣削稳定性研究

【作者】 宋宜德；

【导师】 武凯；

【作者基本信息】 南京理工大学 ， 机械制造及其自动化， 2009， 硕士

【摘要】 整体薄壁框体结构件具有重量轻、强度高、动力性能好等一系列优点,广泛应用于航空、电子、模具等工业领域。由于其具有薄壁、变厚度、曲面曲线结构多、加工余量大等特点,加工过程容易发生颤振,加工质量很难保证,加工效率难以提高。研究整体薄壁框体结构件切削加工颤振问题与稳定性问题具有重要意义。本文对薄壁多框结构件铣削加工颤振机理及其稳定性机理进行了深入的分析,推导了铣削加工三维颤振稳定性模型,建立了动态分析有限元模型,进行了大量有限元模拟运算并与试验结果进行了对比,最后进行了稳定性仿真分析,得出了系列重要结论。本文具体研究内容如下:1.建立了薄壁件铣削加工动态力学模型。分别针对薄壁侧壁和腹板建立了动态力学模型,重点建立了螺旋立铣刀(包括平刀和R刀)和牛鼻铣刀铣削加工薄壁腹板的动态力学模型,并进行了试验验证。在铣削力动态模型的基础上,建立了考虑机床-刀具-工件系统动态特性的薄壁件铣削加工系统动力学模型,为更精确地预测铣削力及分析加工振动及其稳定性奠定了基础。2.对薄壁件铣削加工动态特性进行了深入研究。在前面建立的薄壁件铣削加工系统动力学模型的基础上建立了薄壁件切削加工动态特性有限元分析模型,提出了一种简化加载的薄壁件动态特性分析模型,以简化模型为基础进行了不同切削条件下切削过程中节点振动位移时域模拟,对模拟结果进行了评价,为制定正确的薄壁件切削加工工艺、开展更为复杂的动态分析奠定了基础。3.对薄壁多框结构件进行了模态分析。按照加工顺序分别对不同的加工阶段进行了模态分析,得到了工件在不同加工阶段的模态参数,为后面稳定性分析提供了依据。4.对切削加工颤振理论进行了研究。分析了颤振产生的原理以及颤振的基本特征,并在此基础上给出了稳定性的定义和高速铣削稳定性判据。5.对高速铣削薄壁件的稳定性理论进行了研究。基于已建立的考虑再生颤振的牛鼻铣刀铣削力模型,系统地研究了高速铣削的切削稳定性问题,给出了高速铣削稳定性判据和轴向极限切深的解析解和时域解法,由稳定性极值解析解绘出稳定性图,并基于稳定性图分析了工件动态特性以及机床动态特性对切削稳定性的影响规律。本文的研究工作对实现薄壁框体结构件无颤振高效铣削具有重要指导意义。更多还原

【Abstract】 With characteristics of light mass, high intensity and perfect dynamic performance, the monolithic construction components are used more and more widely in aero, electronic and mold industries. As there are many complex characteristics such as thin-wall, varying thickness, complex curved face and big metal allowance in the monolithic construction components, chatter is an unavoidable phenomenon in all machining processes, causing a reduction in productivity and low quality of finished workpieces. Study on the maching vibration and cutting stability of the monolithic construction components is very important. This paper has theoretically analyzed the chatter and stability cutting of the monolithic construction components firstly. A three-dimensional chatter stability model is presented analytically in this article. Then built the FEM dynamic mechanistic analysis model of milling process. Finally conducted a simulation analysis of milling process. By large quantity of simulations and tests, some important conclusions have been gained. The main work in this paper is concluded as follows.1. Built the dynamic force model of milling thin-walled structure components in detail. In this paper, several dynamic force models are built for milling of aeronautical parts that include thin walls and thin floors. This paper sets up dynamic force models for spiral end mills and bull-nose end mills during milling the thin floors. The model is verified with milling experiment. Based on the model, a dynamic model of the milling system of thin-walled parts is established by considering the machine subsystem, the tool subsystem and the workpiece subsystem. This will be helpful to estimate the cutting forces more accurately and to predict the chatter vibration.2. Studied the milling dynamic characteristics of the thin-walled structure components. Based on the dynamic model of the milling system of thin-walled parts established in the previous paper, the FEM dynamic mechanistic analysis model of milling process is built theoretically. Then a kind of simplified model has been proposed in this paper, and large quantity simulations have been carried out based on the simplified model. The simulation results have been concluded.3. Studied the modal analysis of the thin-walled structure component. The modal analyses are carried out in every machining location. Based on it, modal parameters have been gained which will be helpful to the stability anslysis.4. Studied the chatter in the machining processes. The properties and mechanism of machining vibration have been studied. Then the definition of stability and the prediction method of stability criterion are presented based on it.5. Studied the stability limits of high-speed milling considering the flexibility of the workpiece and the machine. Aimed to bull-nose mill, the dynamic milling force model taking account of regenerative chatter are deduced, and high speed cutting stability is investigated according to dynamic milling force model, then the stability criterion and the ultimate axial depth of cut are studied. Finally, the stability lobes are drawn, and simulated the effect of different modal parameters on stability based on stability lobes.The studies of this paper will be a guide for no chatter milling of the monolithic construction components.更多还原