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毕业设计(论文)外文文献翻译毕业设计(论文)外文文献翻译题目题目 汽车轮毂盘的反求造型研究汽车轮毂盘的反求造型研究专专 业业 名名 称称 机械设计制造及其自动化班班 级级 学学 号号 078105305学学 生生 姓姓 名名 陈 荣指指 导导 教教 师师 于 婓填 表 日 期 2010 年 04 月 08 日数控技术发展趋势数控技术发展趋势1国内外数控系统发展概况随着计算机技术的高速发展,传统的制造业开始了根本性变革,各工业发达国家投入巨资,对现代制造技术进行研究开发,提出了全新的制造模式。在现代制造系统中,数控技术是关键技术,它集微电子、计算机、信息处理、自动检测、自动控制等高新技术于一体,具有高精度、高效率、柔性自动化等特点,对制造业实现柔性自动化、集成化、智能化起着举足轻重的作用。目前,数控技术正在发生根本性变革,由专用型封闭式开环控制模式向通用型开放式实时动态全闭环控制模式发展。在集成化基础上,数控系统实现了超薄型、超小型化;在智能化基础上,综合了计算机、多媒体、模糊控制、神经网络等多学科技术,数控系统实现了高速、高精、高效控制,加工过程中可以自动修正、调节与补偿各项参数,实现了在线诊断和智能化故障处理;在网络化基础上,CAD/CAM与数控系统集成为一体,机床联网,实现了中央集中控制的群控加工。长期以来,我国的数控系统为传统的封闭式体系结构,CNC只能作为非智能的机床运动控制器。加工过程变量根据经验以固定参数形式事先设定,加工程序在实际加工前用手工方式或通过CAD/CAM及自动编程系统进行编制。CAD/CAM和CNC之间没有反馈控制环节,整个制造过程中CNC只是一个封闭式的开环执行机构。在复杂环境以及多变条件下,加工过程中的刀具组合、工件材料、主轴转速、进给速率、刀具轨迹、切削深度、步长、加工余量等加工参数,无法在现场环境下根据外部干扰和随机因素实时动态调整,更无法通过反馈控制环节随机修正CAD/CAM中的设定量,因而影响CNC的工作效率和产品加工质量。由此可见,传统CNC系统的这种固定程序控制模式和封闭式体系结构,限制了CNC向多变量智能化控制发展,已不适应日益复杂的制造过程,因此,对数控技术实行变革势在必行。2数控技术发展趋势2.1性能发展方向(1)高速高精高效化速度、精度和效率是机械制造技术的关键性能指标。由于采用了高速CPU芯片、RISC芯片、多CPU控制系统以及带高分辨率绝对式检测元件的交流数字伺服系统,同时采取了改善机床动态、静态特性等有效措施,机床的高速高精高效化已大大提高。(2)柔性化包含两方面:数控系统本身的柔性,数控系统采用模块化设计,功能覆盖面大,可裁剪性强,便于满足不同用户的需求;群控系统的柔性,同一群控系统能依据不同生产流程的要求,使物料流和信息流自动进行动态调整,从而最大限度地发挥群控系统的效能。(3)工艺复合性和多轴化以减少工序、辅助时间为主要目的的复合加工,正朝着多轴、多系列控制功能方向发展。数控机床的工艺复合化是指工件在一台机床上一次装夹后,通过自动换刀、旋转主轴头或转台等各种措施,完成多工序、多表面的复合加工。数控技术轴,西门子880系统控制轴数可达24轴。(4)实时智能化早期的实时系统通常针对相对简单的理想环境,其作用是如何调度任务,以确保任务在规定期限内完成。而人工智能则试图用计算模型实现人类的各种智能行为。科学技术发展到今天,实时系统和人工智能相互结合,人工智能正向着具有实时响应的、更现实的领域发展,而实时系统也朝着具有智能行为的、更加复杂的应用发展,由此产生了实时智能控制这一新的领域。在数控技术领域,实时智能控制的研究和应用正沿着几个主要分支发展:自适应控制、模糊控制、神经网络控制、专家控制、学习控制、前馈控制等。例如在数控系统中配备编程专家系统、故障诊断专家系统、参数自动设定和刀具自动管理及补偿等自适应调节系统,在高速加工时的综合运动控制中引入提前预测和预算功能、动态前馈功能,在压力、温度、位置、速度控制等方面采用模糊控制,使数控系统的控制性能大大提高,从而达到最佳控制的目的。2.2功能发展方向(1)用户界面图形化用户界面是数控系统与使用者之间的对话接口。由于不同用户对界面的要求不同,因而开发用户界面的工作量极大,用户界面成为计算机软件研制中最困难的部分之一。当前INTERNET、虚拟现实、科学计算可视化及多媒体等技术也对用户界面提出了更高要求。图形用户界面极大地方便了非专业用户的使用,人们可以通过窗口和菜单进行操作,便于蓝图编程和快速编程、三维彩色立体动态图形显示、图形模拟、图形动态跟踪和仿真、不同方向的视图和局部显示比例缩放功能的实现。(2)科学计算可视化科学计算可视化可用于高效处理数据和解释数据,使信息交流不再局限于用文字和语言表达,而可以直接使用图形、图像、动画等可视信息。可视化技术与虚拟环境技术相结合,进一步拓宽了应用领域,如无图纸设计、虚拟样机技术等,这对缩短产品设计周期、提高产品质量、降低产品成本具有重要意义。在数控技术领域,可视化技术可用于CAD/CAM,如自动编程设计、参数自动设定、刀具补偿和刀具管理数据的动态处理和显示以及加工过程的可视化仿真演示等。(3)插补和补偿方式多样化多种插补方式如直线插补、圆弧插补、圆柱插补、空间椭圆曲面插补、螺纹插补、极坐标插补、2D+2螺旋插补、NANO插补、NURBS插补(非均匀有理B样条插补)、样条插补(A、B、C样条)、多项式插补等。多种补偿功能如间隙补偿、垂直度补偿、象限误差补偿、螺距和测量系统误差补偿、与速度相关的前馈补偿、温度补偿、带平滑接近和退出以及相反点计算的刀具半径补偿等。(4)内装高性能PLC数控系统内装高性能PLC控制模块,可直接用梯形图或高级语言编程,具有直观的在线调试和在线帮助功能。编程工具中包含用于车床铣床的标准PLC用户程序实例,用户可在标准PLC用户程序基础上进行编辑修改,从而方便地建立自己的应用程序。(5)多媒体技术应用多媒体技术集计算机、声像和通信技术于一体,使计算机具有综合处理声音、文字、图像和视频信息的能力。在数控技术领域,应用多媒体技术可以做到信息处理综合化、智能化,在实时监控系统和生产现场设备的故障诊断、生产过程参数监测等方面有着重大的应用价值。2.3体系结构的发展(1)集成化采用高度集成化CPU、RISC芯片和大规模可编程集成电路FPGA、EPLD、CPLD以及专用集成电路ASIC芯片,可提高数控系统的集成度和软硬件运行速度。应用FPD平板显示技术,可提高显示器性能。平板显示器具有科技含量高、重量轻、体积小、功耗低、便于携带等优点,可实现超大尺寸显示,成为和CRT抗衡的新兴显示技术,是21世纪显示技术的主流。应用先进封装和互连技术,将半导体和表面安装技术融为一体。通过提高集成电路密度、减少互连长度和数量来降低产品价格,改进性能,减小组件尺寸,提高系统的可靠性。(2)模块化硬件模块化易于实现数控系统的集成化和标准化。根据不同的功能需求,将基本模块,如CPU、存储器、位置伺服、PLC、输入输出接口、通讯等模块,作成标准的系列化产品,通过积木方式进行功能裁剪和模块数量的增减,构成不同档次的数控系统。(3)网络化机床联网可进行远程控制和无人化操作。通过机床联网,可在任何一台机床上对其它机床进行编程、设定、操作、运行,不同机床的画面可同时显示在每一台机床的屏幕上。(4)通用型开放式闭环控制模式采用通用计算机组成总线式、模块化、开放式、嵌入式体系结构,便于裁剪、扩展和升级,可组成不同档次、不同类型、不同集成程度的数控系统。闭环控制模式是针对传统的数控系统仅有的专用型单机封闭式开环控制模式提出的。由于制造过程是一个具有多变量控制和加工工艺综合作用的复杂过程,包含诸如加工尺寸、形状、振动、噪声、温度和热变形等各种变化因素,因此,要实现加工过程的多目标优化,必须采用多变量的闭环控制,在实时加工过程中动态调整加工过程变量。加工过程中采用开放式通用型实时动态全闭环控制模式,易于将计算机实时智能技术、网络技术、多媒体技术、CAD/CAM、伺服控制、自适应控制、动态数据管理及动态刀具补偿、动态仿真等高新技术融于一体,构成严密的制造过程闭环控制体系,从而实现集成化、智能化、网络化。3智能化新一代PCNC数控系统当前开发研究适应于复杂制造过程的、具有闭环控制体系结构的、智能化新一代PCNC数控系统已成为可能。智能化新一代PCNC数控系统将计算机智能技术、网络技术、CAD/CAM、伺服控制、自适应控制、动态数据管理及动态刀具补偿、动态仿真等高新技术融于一体,形成严密的制造过程闭环控制体系。NC technology development trends1 NC system developments at home and abroad With the rapid development of computer technology,the traditional beginning of a fundamental change manufacturing,the industrial developed countries spent huge sums of money on the modern manufacturing technology research and development,to create a new model.In modern manufacturing systems,CNC technology is the key to technology,which combines microelectronics,computers,information processing,automatic detection,automatic control,such as the integration of advanced,a high-precision,high-efficiency,flexible automation,and other characteristics,the manufacturing industry Flexible automation,integrated,intelligent play the pivotal role.At present,NC technology is undergoing a fundamental change,from a special closed-loop control mode to general-purpose real-time dynamic open all closed-loop control mode.In the integrated on the basis of the CNC systems ultra-thin,ultra-light;on the basis of the intelligent,integrated computers,multimedia,fuzzy control,neural network and other technical disciplines,NC system to achieve high-speed,high-precision,Efficient control,automatic processing can be amended to regulate compensation and the parameters for an online intelligent fault diagnosis and treatment of the network based on the CAD/CAM and CNC systems integration as one machine network,makes the central government centralized control of the group control processing.For a long time,Chinas CNC system for traditional closed architecture,but only as a non-intelligent CNC machine controller.Process variables based on experience in the form of pre-fixed parameters,processing procedures before the actual processing by hand or through CAD/CAM and automatic programming system prepared.CAD/CAM and CNC have no feedback control link,the entire manufacturing process CNC is a closed ring-opening implementing agencies.In a complex and changing environment under the conditions of processing tool in the process of composition,workpiece material,spindle speed,feed rate,tool path,cutting depth,step,allowance and other processing parameters,not at the scene circumstances under external interference and real-time dynamic random factors,not by random amendment feedback control link CAD/CAM settings volume,in turn,affect the work of CNC machining efficiency and product quality.Clearly,the traditional fixed CNC system that controlled mode and closed architecture,limiting the CNC to the development of more intelligent control variables,can no longer meet the increasingly complex manufacturing process,therefore,the CNC technology in the potential for change inevitable.2 NC technology development trends 2.1 Performance development direction(1)high-speed high-precision efficient speed,accuracy and efficiency of machinery manufacturing technology is the key performance indicators.As a result of the high-speed CPU chips,RISC chip,as well as multi-CPU control system with high-resolution detector of the absolute exchange digital servo system,taken at the same time improve the machine dynamic and static characteristics of effective measures,the high-speed high-precision machine has been efficient greatly enhanced.(2)Flexible includes two aspects:CNC system itself flexibility,NC system is modular in design,functional coverage,can be cut and strong,and easy to meet the needs of different users;group control system flexibility,with a control system pursuant to the requirements of different production processes,materials flow and information flow automatically dynamically adjusted to maximize their group control system performance.(3)Process of composite and multi-axis to reduce the process time for the main purpose of supporting the composite processing,and are moving towards multi-axis,multi-function control of the direction of series development.NC Machine Tool Technology composite refers to the workpiece in a single machine on a fixture,through an automatic tool change,rotating spindle head or turntable,and other measures to accomplish multiple processes,multi-surface machining compound.Axis CNC technology,Siemens 880-axis control system for up to 24 axes.(4)Real-time Intelligent early for the real-time system is usually relatively simple ideal environment,and its role is to scheduling tasks,to ensure that the task be completed within a specified time limit.And artificial intelligence is used to model the realization of mankinds various intelligent behaviors.To the development of science and technology today,real-time systems and artificial intelligence combined with each other towards artificial intelligence is a real-time response,a more realistic field of development,and also in the real-time system with intelligent behavior,the more complex application development,resulting in the Intelligent real-time control of this new area.NC technology in the field,real-time intelligent control of the research and application of development along several main branches:adaptive control,fuzzy control,neural network control,experts control,learning control,feed-forward control.For example,in CNC programming system with expert systems,fault diagnosis expert system parameters automatically set and tool management and automatic compensation,such as adaptive conditioning systems,in high-speed processing of the integrated motion control ahead of the introduction of budget projections and functional,dynamic Feedforward functions in pressure,temperature,position,velocity,control,fuzzy control,the control of the NC system performance greatly improved,so as to achieve optimal control purposes.2.2 functional development direction(1)The user interface is graphical user interface with the CNC system of dialogue between the user interface.Since different users interface requirements are different,thus the development of the workload of great user interface,user interface software developed into the most difficult part of.At present INTERNET,virtual reality,visualization in scientific computing and multimedia technologies,such as the user interface has put a higher demand.Graphical user interface greatly facilitates the use of non-professional users,it can be carried out through the window and menu operation,ease of programming and blueprint for rapid programming,three-dimensional dynamic three-dimensional color graphics,graphics,simulation,graphics,dynamic tracking and simulation,and the different directions view and partial display ratio scaling function can be achieved.(2)Visualization in scientific computing visualization in scientific computing can be used for efficient data processing and interpretation of data,so that the exchange of information is no longer limited to using the written word and language,and can direct the use of graphics,image,animation,video and other information.Visualization technology and virtual environment technology,to further broaden the application areas,such as a drawing design,virtual prototyping technology,which shorten product design cycles,improving product quality,reduce production cost is of great significance.NC technology in the areas of visualization technology can be used for CAD/CAM,such as automatic programming design parameters automatically set,tool compensation and tool management of dynamic data processing and display,as well as the processing of visual simulation,and other presentations.(3)Interpolation,and a variety of methods of compensation interpolation methods such as multiple linear interpolation,circular interpolation,cylindrical interpolation,space elliptical surface interpolation,thread interpolation,polar coordinates interpolation,2 D+2 helical interpolation,NANO interpolation,interpolation NURBS(non-uniform rational B-spline interpolation),spline interpolation(A,B,C kind),such as polynomial interpolation.A variety of functions such as compensation gap compensation vertical compensation quadrant error compensation,and measurement systems pitch error compensation,and speed-related feedforward compensation and temperature compensation,with nearly smooth and exit,as well as the opposite point of the cutter radius compensation.(4)High-performance PLC contents contents performance CNC system PLC control module can be directly used ladder diagram or high-level language programming,with intuitive online debugging and online help function.Programming tools include the standard used lathe and milling machine PLC user program an example,users may PLC user program standards on the basis of editorial changes,thus easily build their own applications.(5)Application of multimedia technology of multimedia technology-computers,audio-visual and communication technology,and it has the computer integrated voice,text,images and video information.In NC technology,multimedia technology can be applied to information processing integrated,intelligent,real-time monitoring system in the field and production equipment fault diagnosis,monitoring of process parameters such as production has a significant value.2.3 Development of the Architecture(1)Integration of a highly integrated CPU,programmable RISC chips and large-scale integrated circuits FPGA,EPLD,CPLD and ASIC ASIC chips that can improve the CNC system integration and hardware and software operating speed.Application FPD flat panel display technology can improve display performance.Flat-panel displays with high science and technology content,light weight,small size,low power consumption and portability advantages can be realized Supersized,a counterweight to the emerging and CRT display technology,display technology in the 21st century the mainstream.Application of advanced packaging and interconnect technologies,semiconductors and surface mount technology integration.By increasing the density of integrated circuits,reducing the length and number of interconnection products to reduce prices,improve performance,reduce component size,improve the reliability of the system.(2)Easy to implement modular hardware modular NC systems integration and standardization.According to various functional requirements,the basic modules,such as CPU,memory,position servo,PLC,the input and output interfaces,and communications modules,making the standard Series products,through functional building-block approach to cutting the number of steps and modules,a NC system at different grades.(3)Machine interconnection network for remote control of unmanned operation.Machine through networking,can be in any one machine on the other machine programming,configuration,operation,operating,different machine can be displayed on the screen each machine on the screen.(4)General-open the closed-loop control mode to adopt a common computer component Bus,modular,open,embedded architecture,ease of cutting,expansion and upgrading,can be composed of different grades,different types,different degree of integration CNC system.Closed-loop control mode is the traditional CNC system only for single closed-open-loop control mode proposed.The manufacturing process is a multi-variable control and the role of integrated processing complex process,including processing,such as size,shape,vibration,noise,temperature and thermal deformation,and other factors,therefore,to achieve the process of multi-objective optimization,Multivariable must adopt the closed-loop control,real-time processing in the dynamic adjustment process variables.Processing the adoption of open u
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