【作者】 沈春根；

【导师】 王贵成；

【作者基本信息】 江苏大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 高速加工是集制造技术、材料科学、信息科学和控制理论为一体的综合高新技术,在汽车、模具、航空航天等制造领域得到了广泛的应用,并取得了显著的经济效益。高速加工工具系统是高速精密数控机床的重要组成部分,其结构特性、动态性能和动平衡性等直接影响和制约着高速加工质量和生产效率,因此,系统开展工具系统动力学特性及基础应用技术的研究具有重要的学术价值和应用前景。本文采用理论分析、数值计算、振动测试和切削加工实验相结合的方法,以高速加工工具系统为研究对象,在建立其动力学理论模型的基础上,系统、全面地分析了高速加工工具系统的结构模态参数、工况振动特性和动态响应的变化规律,进而实现其动态结构的整体优化,主要工作及创新成果为：1.基于FEM和EMA相结合,首次构建了高速加工工具系统的动力学实体模型基于线弹性理论,采用有限元模态分析(Finite Element Method,简称FEM)和实验模态分析(Experiment Modal Analysis,简称EMA)相结合的方法,构建了高速加工工具系统在自由状态、工况约束条件下的动力学实体模型,计算出系统的各阶固有频率和振型,通过实验模态分析方法验证了有限元模型构建过程和计算结果的合理性,在此有限元模型的基础上,分析了刀杆直径、刀杆长度、联接过盈量等结构因素对工具系统结构模态参数的影响规律,分析了主轴和刀柄联接过盈量和接触效果对主轴—工具系统结构模态参数的影响程度。2.系统揭示出工具系统在动态激励下的动态响应特性及其变化规律在构建工具系统有限元动力学模型和分析工具系统所受动态激励类型的基础上,计算和分析了工具系统承受不平衡量和动态切削力的动态响应及变化规律。通过机床升速空运转振动测试,比较了主轴系统空运转和主轴-工具系统空运转各自的振动特性。测试了不同平衡量大小的工具系统在空运转时的振动特性,揭示了工具系统承受强迫振动的频响结构,为有效降低整个加工系统的振动响应提供了理论依据。3.基于不平衡量系统分析了工具系统的振动特性设计了不平衡量大小可调的工具系统和采用多因素正交切削试验,全面分析了不平衡量和切削用量对主轴振动、加工工件振动、三向动态切削力和加工表面粗糙度的影响程度、主次关系和变化规律,验证了工具系统不平衡量动态响应的理论计算结果,同时为高速切削选用合理的切削用量提供了重要参考。4.首次实现了刀柄和主轴接触疲劳寿命的预测预报在构建工具系统屈曲响应模型的基础上,计算和分析了工具系统在工况条件下屈曲响应的主要的影响因素及变化规律。进一步构建了主轴—工具系统接触的有限元模型,借助专用疲劳分析软件的基础上,评估了各个接触区域的疲劳应力因子和疲劳安全因子,预测了各个区域的疲劳寿命,为深入研究主轴／刀柄联接锥面疲劳失效机理提供理论参考。5.基于工具系统模态参数和结构优化,提出了开发新型工具系统的一种新方法在构建工具系统动力学有限元模型的基础上,以其工况固有频率为优化目标,根据工况要求对其模态参数和结构尺寸进行了优化,使其在工作状况下的动态性能到达了最佳化,为开发新型工具系统能够在高速工况发挥其最佳动态性能提供了一种新的方法。系统地开展高速加工工具系统动力学特性的基础理论、振动特性测试和基于不平衡量的切削加工实验的研究和运用,既丰富了工具系统共性技术的研究,在实际应用中也有助于充分发挥高速加工工具系统的动态性能,这对推动高速加工技术的应用、发展先进制造技术具有重要的理论价值和实际意义。本研究是国家自然科学基金项目《高速切削中毛刺的形成机理及其控制(No50675088)》、国家十五科技攻关项目《高速加工工具系统的开发与应用(No2001BA205B05/05)》和国务院重大专项《高档数控机床与基础制造装备中“高速数控机床用新型工具系统”(2009ZX04012-012)》的组成部分之一。更多还原

【Abstract】 High speed machining is a combination of manufacturing technology, materials science, information science and control theory as an integrated high-tech, automotive, mould, aerospace and other manufacturing fields has been widely used, and has achieved significant economic benefits. High speed tooling system is an important part of CNC machine tools, their structural characteristics, dynamic performance, balancing capability and so directly affect and constrain the quality and efficiency of high speed machining, so as to the researching of basic theoretical study and applied technology of tooling system has great academic value and prospects. Combining with the methods of theoretical analysis, numerical computation, vibration test and cutting experiment, taking high speed machining tooling system as a study object and on the basis of establishing its dynamic model, the changing laws of the tooling system structural modal parameter, working vibration property and dynamic response were investigated systematically and comprehensively, and its optimization goal of dynamic structure was achieved, the main work and innovations of this paper as fellows:1. The dynamic soild model of the tooling system was established by the way of jointing FEM with EMA.Based on linear-elastic theory, by way of finite element modal analysis and experimental modal analysis, the FEM dynamic soild models of the high speed tooling system in the free state and operating constraint condition were established, and the all natural frequencies and vibration models were calculated. The construction and calculation of the finite element model were confirmed to be reasonable by experimental modal analysis method. On the basis of rational FEM model of tooling system, the influence degree and laws on tooling system structural modal parameters were calculated and analyzed according to various types, arbor diameter, arbor coolant hole diameter, arbor length, arbor/cutter coupling interference, contact effect and so on, and the influence degree and changing laws on spindle-tool system structural modal parameters caused by spindle/holder coupling interference were analyzed, then these research provided a theoretical basis for rational evaluation on dynamic performance of high speed tooling system.2. The performances of tooling system dynamic response in dynamic excitation and its variation were systematically revealed.Based on constructing the FEM dynamic model of high speed tooling system and analyzing the dynamic incentive types which the tooling system suffered, the dynamic response of its overall structure caused by unbalance and dynamic cutting force were calculated, and By way of the vibration testing of raising speed, the vibration characteristics of spindle system and spindle-tool system under the condition of idle running were compared. The vibration characteristics were tested and analyzed according to various value of imbalance when tooling system was idle running, and its frequency response composition under forced vibration was revealed, and also to effectively reduce the vibration response of the spindle-tooling system provided a theoretical basis.3. The vibration characteristeric of tooling system based on its imbalance was systematically analyzed.A tooling system with adjustable unbalance ring was designed, by way of the multi-factor orthogonal cutting experiment in high speed, the degree of influence and changing laws of the spindle vibration, workpiece vibration, three-dimensional cutting force and roughness of the machined surface caused by the imbalance and cutting parameters were analyzed comprehensively, and the dynamic response laws of the tooling system unbalance were verified, finally an important reference of choosing the reasonable tooling system for high speed machining was provided.4. The buckling response of tooling system was calculated and the fatigue lifetime of contact area between spindle and tool-holder was predicted for the first time. The structural stability of the tooling system itself was to ensure the stability of cutting process, so based on the buckling response model of tooling sytem, the influence factors and changing laws of the tooling system buckling response in operating condition were calculated and analyzed. On the basis of building rational FEM model and by way of special fatigue analysis software, the most likely occurring fatigue area on the spindle-toolholder in theory was found out, not only the fatigue stress factor but also fatigue safety actor of various regions were evaluated and the fatigue lifetime was also predicted, finally the research results offered a theoretical consideration for the further study of spindle-toolholder interface’s fatigue failure mechanism and structure optimizational designing.5. Based on the tooling system structural modal parameters and its optimization, present a new way for the development of new-type tooling system. Based on setting up the parametric model of the tooling system and dynamic finite element model, the parametric model and structural size were optimized according to the working conditions and the dynamic performance was to be the best in working conditions, a new study idea was provided for researching and development the new type of tooling system and application in engineering. Systematically studying the basic theory, vibration testing and cutting experiment of dynamic characteristics of high speed tooling system, and this not only can enrich researching the common technologies of tooling system, in practice, but also can help to improve tooling syetm dynamic performance under high speed machining. These researching results have great theoretical and practical significance for promoting application of high speed machining technology and developing advanced manufacturing technology.This paper is the main part of the project’Develop and Application of Tooling System in High Speed Machining’supported by’Burr formation mechanism and controlling in high speed cutting’(Grant No.50675088), National Key Technologies R&D Program in the 10th five-year plan (Grant No.2001BA205B05) and project’New-type Tooling System in High Speed CNC Machine Subjected to CNC Machine and Basic Manufacturing Equipment’supported by the National S&T major project foundation (Grant No.2009ZX04012-012).更多还原