【作者】 唐委校；

【导师】 艾兴；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2005， 博士

【摘要】 高速切削加工具有高效率、高精度和低成本的突出优势,是最重要、最具共性的先进制造技术之一,具有广阔的发展应用前景。高速切削系统(包括机床、刀具、工件和切削过程)是复杂的动态系统,随着切削速度的提高,切削过程中的振动导致的不稳定切削对生产效率、加工质量、成本以及机床和刀具寿命的影响比普通速度切削大得多。高速切削加工的诸多优越性的发挥必须以无振动稳定切削的实现为前提。目前,关于高速切削稳定性分析预测及其动态优化理论与方法的研究很少,严重限制了高速切削技术的发展。因此,以实现稳定切削条件下的高生产效率和高加工质量为优化目标,提出在高速切削机床和刀具的设计、制造、检验、切削加工生产与维护的整个生命周期中进行考虑切削稳定性的动态优化的新理念,研究适合高速切削特点的切削稳定性预测及其动态优化理论和工程应用方法,是促进高速切削技术发展和应用的重要应用基础课题,对充分发挥高速切削的技术优势和经济优势具有重要的理论意义和现实意义。 探讨适合高速切削特点的高速切削系统动力学模型及其建模方法,据Lagrange方程,建立了考虑高转速下离心力和陀螺力矩等多变量影响的高速切削系统多自由度动力学模型。以DMU-70V五轴高速加工中心(HSK主轴-刀柄联结)和ACE-V500立式加工中心(BT主轴-刀柄联结)为例,分析比较了离心力和陀螺力矩对不同机床主轴-刀柄结构及其与不同刀具(立铣刀、面铣刀,不同直径、齿数、外伸长径比)匹配时在不同支承刚度、不同转速下的动态特性的影响。界定了不同主轴刀柄结构需考虑离心力和陀螺力矩影响的临界转速范围。数值计算和实验结果表明,高转速下离心力和陀螺力矩的影响不能忽略,HSK主轴-刀柄结构在高速下的动态特性明显好于BT结构。 针对高速切削的特点,考虑在高速切削中不同切削条件和切削过程的振动对切削力的影响,建立高速切削过程的动态切削力模型。以螺旋立铣刀为例分析了不同切削条件对动态切削力的影响。 基于所建的动力学模型和动态切削力分析,研究了高速切削过程的再生型自激振动、自激振动与强迫激励共同作用下的混合振动的稳定性判据及其稳定切削更多还原

【Abstract】 High-speed machining (HSM) possessed outstanding advantages of high efficiency and high precision is one of the most important advanced manufacturing technologies and has wide application prospects. The HSM system (including machines, tools, workpierce and machining process) is complex dynamic one. With the increase of machining speed, the influence of instable machining caused by vibration in machining process on efficiency, surface quality, production cost as well as use time of machines and tools is larger than conventional cutting speed. The stable machining process is one of the preconditions of realizing the advantages of HSM technology. However, the shortage of research on stability predication and optimization theory and method of HSM system limits the development and reasonable application of the HSM technology. Therefore, a new conception of stability optimization used in the whole life cycle of the design, manufacture, inspection and machining operation and maintenance of HSM system is proposed, and the stability predication, optimization theory and method suitable HSM is researched. It is a important application foundation subject for promote high-speed machining technical development and application and have very important theoretical and realistic meaning to bring high-speed machining into technological advantage and economic advantage further.Studying the dynamic model and modeling method suit to the characteristics of HSM system, based on Lagrange’s equation, the dynamics model of HSM system with multi-degrees of freedom are set up with respect to the influence of centrifugal force and gyroscopic moment due to high rotating speed on dynamic characteristics of system. Take DMU-70V five-axis machining center (with HSK spindle/holder) and ACE-V500 vertical-type machining center (with BT spindle/holder) as examples, the influence of centrifugal force and gyroscopic moment on dynamic characteristics of different spindle/holder and cutters (end milling cutter, face milling cutter) are analyzed and compared with matching in different bearing rigidity under different rotate speed. The critical rotate speed and operation speed ranges in which the influence of centrifugal force and gyroscopic moment must be considered are determined. And the results analyzed show that the dynamic characteristics of HSK spindle/holder in high speed are better than ones of BT spindle/holder.Considering the influence of different cutting condition and vibration in high speed cutting process on cutting force, a dynamic cutting force model with respect to high speed machining is established. Take helix end milling as an example, the influence of different cutting condition to dynamic cutting force is analyzed and compared by analytical predication and cutting experiments.Based on the dynamic cutting force and dynamics model established, the stability criterion and predicting method of the regenerative self-excited chatter and the mix vibration excited by both self-excited chatter and outside loads in high speed machining process is studied. The mode orthogonality are used to analyse the frequency response of the multi-degrees of freedom system, the predicting method of stability criterion and limits with respect to high order eigen-frequenceis of multi-degrees of freedom in high speed machining is proposed. In this way, the stability limits (lobe) diagram method of multi-degrees of freedom high speed machining system is established and the effect of structure parameter and cutting process parameter to high speed machining stability is analysed. And the stability lobe diagram of DMU-70V and ACE-V500 machining centers are given, which can be referenced in real production.Apply structural dynamic modification technique to the dynamic optimization for stability of HSM system, which is a "converse problem" of dynamics, and extent and improve it. Transforming the "converse problem" which aimed at high material remove ratio and high surface quality under stable cutting to "positive problem" which is based on step modification and reanalysis, the dynamic modification-based optimization theory and method for stability of HSM system are investigated. The synthetical optimization method for both the stability limit and machine tool’s power utilization efficiency are proposed. In each stage of design and machining process, the different design variables including structural parameters and machining parameters are determined and modified repeat up to the desired optimum objectives are achieved by means of the sensitiveness and the perturbation analysis. And results achieved show that the material remove rate and surface quality had improved evidently and economically by optimizing drawbar force of spindle, rotating speed, axial cutting depth, number of teeth and overhung length of tool, as well as clamp of workpiece etc.Experimentations of modal analysis, idling of spindle and high-speed milling are designed and carried out to investigate and validate the dynamics models, theory andmethod proposed and the dynamic characteristics, machining stability on both DMU-70V and ACE-V500 machining centers. And the experimental methods suitable for performance examination and evaluation of HSM system with respect to stability are researched and established.更多还原