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Numerical Control SystemThe numerical control system is the digital control system abbreviation. By early is composed of hardware circuit is called hardware numerical control (Hard NC), after 1970, hardware circuit components gradually instead by the computer called for computer numerical control system. Computerized numerical control system is a system that is use computer control processing function to achieve numerical control system. CNC system according to the computer memory stored in the control program execution part or all, numerical control function, and is equipped with interface circuit and servo drive the special computer system. CNC system consists of NC program, input devices; output devices, computer numerical control equipment (CNC equipment), programmable logic controllers (PLC), the spindle and feed drive (servo) drive (including detection devices) and so on. The core of CNC system is equipment. By using the computer system with the function of software and PLC instead of the traditional machine electric device to make the system logic control more compact, its flexibility and versatility, reliability become more better, easy to implement complex numerical control function, use and maintenance can be more convenient, and it also has connected and super ordination machine and the remote communication function. At present, the numerical control system has variety of different forms; composition structure has its own characteristics. These structural features from the basic requirements of the initial system design and engineering design ideas. For example, the control system of point and continuous path control systems have different requirements. For the T system and the M system, there are also very different, the former applies to rotary part processing, the latter suitable for special-shaped the axially symmetrical parts processing. For different manufacturers, based on historical development factors and vary their complex factors, may also be thinking in the design is different. For example, the United States Dynapath system uses a small plate for easy replacement and flexible combination of the board; while Japan FANUC system is a large plate structure tends to make the system work in favor of reliability, make the system MTBF rate continues to increase. However, no matter what kind of system, their basic principle and structure are very similar. The numerical control system generally consists of three major components, namely the control system, servo system and position measuring system. Control procedures by interpolation operation work piece, issue control instructions to the servo drive system; servo drive system control instructions amplified by the servo motor-driven mechanical movement required; measurement system detects the movement of mechanical position or speed, and feedback to the control system, to modify the control instructions. These three parts combine to form a complete closed-loop control of the CNC system. Control system mainly consists of bus, CPU, power supply, memory, operating panel and display, position control unit, programmable logic controller control unit and data input / output interface and so on. The latest generation of CNC system also includes a communication unit; it can complete the CNC, PLCs internal data communications and external high-order networks. Servo drive system including servo drives and motors. Position measuring system is mainly used grating, or circular grating incremental displacement encoder. CNC system hardware from the NC device, input / output devices, drives and machine logic control devices, electrical components, between the four parts through the I / O interface to interconnect. Numerical control device is the core of CNC system, its software and hardware to control the implementation of various CNC functions. The hardware structure of no device by CNC installations in the printed circuit board with infixing pattern can be divided into the big board structure and function module (small board) structure; Press CNC apparatus hardware manufacturing mode, can be divided into special structure and personal computer type structure; Press CNC apparatus in the number of microprocessor can be divided into single microprocessor structure and many microprocessor structure. (1)Large panel structure and function templates structure 1) Large panel structure Panel structures CNC system CNC equipment from the main circuit board, position control panels, PC boards, graphics control panel, additional I / O board and power supply unit and other components. The main circuit board printed circuit board is big; the other circuit board is a small plate, inserted in the large printed circuit board slot. This structure is similar to the structure of micro-computer. 2) Function templates structure(2)Single-microprocessor structure and mulct-microprocessor structure 1) Single-microprocessor structureIn a single-microprocessor structure, only a microprocessor to focus on control, time-sharing deals with the various tasks of CNC equipment. 2) melt-microprocessor structure With the increase in numerical control system functions, CNC machine tools to improve the processing speed of a single microprocessor CNC system can not meet the requirement; therefore, many CNC systems uses a multi-microprocessor structure. If a numerical control system has two or more microprocessors, each microprocessor via the data bus or communication to connect, share system memory and common I / O interfaces, each processor sharing system Part of the work, which is multi-processor systems.CNC software is divided into application software and system software. CNC system software for the realization of various functions of the CNC system, the preparation of special software, also known as control software, stored in the computer EPROM memory. CNC Systems feature a variety of settings and different control schemes, and their system software in the structure and size vary widely, but generally include input data processing procedures, computing interpolation procedures, speed control procedures, management procedures and diagnostic procedures.(1)Input data processing proceduresIt receives input part program, the standard code, said processing instructions and data decoding, data processing, according to the prescribed format for storage. Some systems also calculated to compensate, or interpolation operation and speed control for pre-computation. Typically, the input data processing program, including input, decoding and data processing three elements.(2)Computing interpolation proceduresCNC work piece processing system according to the data provided, such as curve type, start, end, etc. operations. According to the results of operations were sent to each axis feed pulse. This process is called interpolation operation. Feed drive servo system Impulsive table or by a corresponding movement of the tool to complete the procedural requirements of the processing tasks.Interpolation for CNC system is the side of the operation, while processing, is a typical real-time control, so the interpolation directly affects the speed of operation the machine feed rate, and should therefore be possible to shorten computation time, which is the preparation of interpolation Complements the key to the program.(3)Speed control proceduresSpeed control program according to the given value control the speed of operation of the frequency interpolation, in order to maintain a predetermined feed rate. Changes in speed is large, the need for automatic control of acceleration and deceleration to avoid speed drive system caused by mutations in step.(4)Management procedures Management procedures responsible for data input, data processing, interpolation processing services operations as the various procedures for regulation and management. Management process but also on the panel command, the clock signal, the interrupt caused by fault signals for processing.(5)Diagnostic proceduresDiagnostic features are found in the running system failure in a timely manner, and that the type of failure. You can also run before or after the failure, check the system main components (CPU, memory, interfaces, switches, servo systems, etc.) function is normal, and that the site of failure.Machining Any machining must have three basic conditions: machining tools, work piece and machining sports. Machining tool edge should be, the material must be rigid than the work piece. Different forms of tool structure and cutting movements constitute different cutting methods. Blade with a blade-shaped and have a fixed number of methods for cutting tools for turning, drilling, boring, milling, planning, broaching, and sawing, etc.; edge shape and edge with no fixed number of abrasive or abrasive Cutting methods are grinding, grinding, honing and polishing. Machining is the most important machinery manufacturing processing methods. Although the rough improve manufacturing precision, casting, forging, extrusion, powder metallurgy processing applications on widely, but to adapt to a wide range of machining, and can achieve high accuracy and low surface roughness, in Manufacturing still plays an important role in the process. Cutting metal materials have many classifications. Common are the following three kinds. By cutting process feature distinguishing characteristics of the decision process on the structure of cutting tools and cutting tools and work piece relative motion form. According to the technical characteristics of cutting can be divided into: turning, milling, drilling, boring, reaming, planning, shaping, slotting, broaching, sawing, grinding, grinding, honing, super finishing, polishing, gear Processing, the worm process, thread processing, ultra-precision machining, bench and scrapers and so on. By material removal rate and machining accuracy distinction can be divided into: rough: with large depth of cut, one or a few times by the knife away from the work cut out most or all allowances, such as rough turning, rough planning, Rough milling, drilling and sawing, etc., rough machining precision high efficiency low, generally used as a pre-processing, and sometimes also for final processing. Semi-finishing: General roughing and finishing as the middle between the process, but the work piece accuracy and surface roughness on the less demanding position, but also can be used as the final processing. finishing: cutting with a fine way to achieve higher machining surface accuracy and surface quality, such as fine cars, fine planning, precision hinges, grinding and so on. General is the final finishing process. Finishing process: after the finish, the aim is to obtain a smaller surface roughness and to slightly improve the accuracy. Finishing processing allowance is small, such as honing, grinding, ultra-precision grinding and super finishing and so on. Modification process: the aim is to reduce the surface roughness, to improve the corrosion, dust properties and improve appearance, but does not require higher precision, such as polishing, sanding, etc. ultra-precision machining: aerospace, lasers, electronics, nuclear energy and other cutting-edge technologies that need some special precision parts, high accuracy over IT4, surface roughness less than Ra 0.01 microns. This need to take special measures to ultra-precision machining, such as turning mirror, mirror grinding, chemical mechanical polishing of soft abrasive. Distinguished by method of surface machining, the work piece is to rely on the machined surface for cutting tool and the work piece to obtain the relative motion. By surface methods, cutting can be divided into three categories. tip trajectory method: relying on the tip relative to the trajectory of the surface to obtain the required work piece surface geometry, such as cylindrical turning, planning surface, cylindrical grinding, with the forming surface, such as by turning mode. The trajectory depends on the tool tip provided by the cutting tool and work piece relative motion. forming tool method: short forming method, with the final work piece surface profile that matches the shape forming cutter or grinding wheel, such as processing a shaped surface. At this time forming part of the machine movement was replaced by the blade geometry, such as the shape of turning, milling and forming grinding forming and so on. The more difficult the manufacture of forming cutter, machine - clamp - work piece - tool formed by the process system can withstand the cutting force is limited, forming method is generally used for processing short shaped surface. generating method: also known as rotary cutting method, cutting tool and work piece during processing as a relatively developed into a campaign tool (or wheel) and the work piece instantaneous center line of pure rolling interaction between the two maintain a certain ratio between Is obtained by processing the surface of the blade in this movement in the envelope. Gear machining hobbling, gear shaping, shaving, honing, and grinding teeth (not including form grinding teeth), etc. are generating method processing.PLC Early called the programmable logic controller PLC (Programmable Logic Controller, PLC), which is mainly used to replace the logic control relays. With the technology, which uses micro-computer technology, industrial control device function has been greatly exceeded the scope of logic control, therefore, such a device today called programmable logic controller, referred to as the PC. However, in order to avoid personal computer (Personal Computer) in the short confusion, it will be referred to as programmable logic controller PLC, plc since 1966, the U.S. Digital Equipment Corporation (DEC) developed there, the current United States, Japan, Germany, PLC Good quality and powerful. The basic structure of Programmable Logic ControllerA. Power PLCs power in the whole system plays a very important role. If you do not have a good, reliable power system is not working, so the PLC manufacturers design and manufacture of power very seriously. General AC voltage fluctuations of +10% (+15%) range, you can not take other measures to PLC to connect directly to the AC line.B.Central processing unit (CPU) Central processing unit (CPU) is the central PLC control. It is given by the function of PLC system program from the programmer receives and stores the user program and data type; check the power supply, memory, I / O and timer alert status, and to diagnose syntax errors in the user program. When the PLC into run-time, first it scans the scene to receive the status of various input devices and data, respectively, into I / O image area, and then one by one from the user program reads the user program memory, after a shell and press Provisions of the Directive the result of logic or arithmetic operations into the I / O image area or data register. And the entire user program is finished, and finally I / O image area of the state or the output of the output register data to the appropriate output device, and so on to run until stopped. To further improve the reliability of PLC, PLC is also large in recent years constitutes a redundant dual-CPU system, or by three voting systems CPU. Thus, even if a CPU fails, the whole system can still work properly.C.Memory Storage system software of memory called system program memory. Storage application software of memory called the user program memory.D.Input and output interface circuit 1, the live input interface circuit by the optical coupling circuit and the computer input interface circuit, the role of PLC and field control of an interface for input channels. 2, Field output interface circuit by the output data registers, interrupt request strobe circuit and integrated circuit, the role of PLC output interface circuit through the on-site implementation of parts of the output to the field corresponding control signal.E.Function module Such as counting, positioning modules.F.Communication module Such as Ethernet, RS485, Prefabs-DP communication module. 数控系统数控系统是数字控制系统简称，英文名称为Numerical Control System，早期是由硬件电路构成的称为硬件数控（Hard NC），1970年代以后，硬件电路元件逐步由专用的计算机代替称为计算机数控系统。 计算机数控（Computerized numerical control,简称CNC）系统是用计算机控制加工功能，实现数值控制的系统。CNC系统根据计算机存储器中存储的控制程序，执行部分或全部数值控制功能，并配有接口电路和伺服驱动装置的专用计算机系统。 CNC系统由数控程序、输入装置、输出装置、计算机数控装置（CNC装置）、可编程逻辑控制器（PLC）、主轴驱动装置和进给（伺服）驱动装置（包括检测装置）等组成。 CNC系统的核心是CNC装置。由于使用了计算机，系统具有了软件功能，又用PLC代替了传统的机床电器逻辑控制装置，使系统更小巧，其灵活性、通用性、可靠性更好，易于实现复杂的数控功能，使用、维护也方便，并具有与上位机连接及进行远程通信的功能。 目前世界上的数控系统种类繁多，形式各异，组成结构上都有各自的特点。这些结构特点来源于系统初始设计的基本要求和工程设计的思路。例如对点位控制系统和连续轨迹控制系统就有截然不同的要求。对于T系统和M系统，同样也有很大的区别，前者适用于回转体零件加工，后者适合于异形非回转体的零件加工。对于不同的生产厂家来说，基于历史发展因素以及各自因地而异的复杂因素的影响，在设计思想上也可能各有千秋。例如，美国Dynapath系统采用小板结构，便于板子更换和灵活结合，而日本FANUC系统则趋向大板结构，使之有利于系统工作的可靠性，促使系统的平均无故障率不断提高。然而无论哪种系统，它们的基本原理和构成是十分相似的。 一般整个数控系统由三大部分组成，即控制系统，伺服系统和位置测量系统。控制系统按加工工件程序进行插补运算，发出控制指令到伺服驱动系统；伺服驱动系统将控制指令放大，由伺服电机驱动机械按要求运动；测量系统检测机械的运动位置或速度，并反馈到控制系统，来修正控制指令。这三部分有机结合，组成完整的闭环控制的数控系统。 控制系统主要由总线、CPU、电源、存贮器、操作面板和显示屏、位控单元、可编程序控制器逻辑控制单元以及数据输入/输出接口等组成。最新一代的数控系统还包括一个通讯单元，它可完成CNC、PLC的内部数据通讯和外部高次网络的连接。伺服驱动系统主要包括伺服驱动装置和电机。位置测量系统主要是采用长光栅或圆光栅的增量式位移编码器。 数控系统的硬件由数控装置、输入/输出装置、驱动装置和机床电器逻辑控制装置等组成，这四部分之间通过I/O接口互连。 数控装置是数控系统的核心，其软件和硬件来控制各种数控功能的实现。 数控装置的硬件结构按CNC装置中的印制电路板的插接方式可以分为大板结构和功能模块（小板）结构；按CNC装置硬件的制造方式，可以分为专用型结构和个人计算机式结构；按CNC装置中微处理器的个数可以分为单微处理器结构和多微处理器结构。 （1）大板结构和功能模板结构 1）大板结构 大板结构CNC系统的CNC装置由主电路板、位置控制板、PC板、图形控制板、附加I/O板和电源单元等组成。主电路板是大印制电路版，其它电路板是小板，插在大印制电路板上的插槽内。这种结构类似于微型计算机的结构。 2）功能模块结构 （2）单微处理器结构和多微处理器结构 1）单微处理器结构 在单微处理器结构中，只有一个微处理器，以集中控制、分时处理数控装置的各个任务。 2）多微处理器结构 随着数控系统功能的增加、数控机床的加工速度的提高，单微处理器数控系统已不能满足要求，因此，许多数控系统采用了多微处理器的结构。若在一个数控系统中有两个或两个以上的微处理器，每个微处理器通过数据总线或通信方式进行连接，共享系统的公用存储器与I/O接口，每个微处理器分担系统的一部分工作，这就是多微处理器系统。 CNC软件分为应用软件和系统软件。CNC系统软件是为实现CNC系统各项功能所编制的专用软件，也叫控制软件，存放在计算机EPROM内存中。各种CNC系统的功能设置和控制方案各不相同，它们的系统软件在结构上和规模上差别很大，但是一般都包括输入数据处理程序、插补运算程序、速度控制程序、管理程序和诊断程序。 （1）输入数据处理程序 它接收输入的零件加工程序，将标准代码表示的加工指令和数据进行译码、数据处理，并按规定的格式存放。有的系统还要进行补偿计算，或为插补运算和速度控制等进行预计算。通常，输入数据处理程序包括输入、译码和数据处理三项内容。 （2）插补计算程序 CNC系统根据工件加工程序中提供的数据，如曲线的种类、起点、终点等进行运算。根据运算结果，分别向各坐标轴发出进给脉冲。这个过程称为插补运算。进给脉冲通过伺服系统驱动工作台或刀具作相应的运动，完成程序规定的加工任务。 CNC系统是一边插补进行运算，一边进行加工，是一种典型的实时控制方式，所以，插补运算的快慢直接影响机床的进给速度，因此应该尽可能地缩短运算时间，这是编制插补运算程序的关键。 (3)速度控制程序 速度控制程序根据给定的速度值控制插补运算的频率，以保预定的进给速度。在速度变化较大时，需要进行自动加减速控制，以避免因速度突变而造成驱动系统失步。 (4)管理程序 管理程序负责对数据输入、数据处理、插补运算等为加工过程服务的各种程序进行调度管理。管理程序还要对面板命令、时钟信号、故障信号等引起的中断进行处理。 (5)诊断程序 诊断程序的功能是在程序运行中及时发现系统的故障，并指出故障的类型。也可以在运行前或故障发生后，检查系统各主要部件（CPU、存储器、接口、开关、伺服系统等）的功能是否正常，并指出发生故障的部位。 切削加工 任何切削加工都必须具备3个基本条件:切削工具、工件和切削运动。切削工具应有刃口，其材质必须比工件坚硬。不同的刀具结构和切削运动形式构成不同的切削方法。用刃形和刃数都固定的刀具进行切削的方法有车削、钻削、镗削、铣削、刨削、拉削和锯切等；用刃形和刃数都不固定的磨具或 磨料进行切削的方法有磨削、研磨、珩磨和抛光等。切削加工是机械制造中最主要的加工方法。虽然毛坯制造精度不断提高，精铸、精锻、挤压、粉末冶金等加工工艺应用日广，但由于切削加工的适应范围广，且能达到很高的精度和很低的表面粗糙度，在机械制造工艺中仍占有重要地位。金属材料的切削加工有许多分类方法。常见的有以下3种。 按工艺特征区分 切削加工的工艺特征决定于切削工具的结构以及切削工具与工件的相对运动形式。按工艺特征，切削加工一般可分为：车削、铣削、钻削、镗削、铰削、刨削、插削、拉削、锯切、磨削、研磨、珩磨、超精加工、抛光、齿轮加工、蜗轮加工、螺纹加工、超精密加工。按材料切除率和加工精度区分 可分为：粗加工：用大的切削深度，经一次或少数几次走刀从工件上切去大部分或全部加工余量，如粗车、粗刨、粗铣、钻削和锯切等，粗加工加工效率高而加工精度较低，一般用作预先加工，有时也可作最终加工。半精加工：一般作为粗加工与精加工之间的中间工序，但对工件上精度和表面粗糙度要求不高的部位，也可以作为最终加工。精加工：用精细切削的方式使加工表面达到较高的精度和表面质量，如精车、精刨、精铰、精磨等。精加工一般是最终加工。精整加工：在精加工后 进行，其目的是为了获得更小的表面粗糙度，并稍微提高精度。精整加工的加工余量小，如珩磨、研磨、超精磨削和超精加工等。修饰加工：目的是为了减小表面粗糙度，以提高防蚀、防尘性能和改善外观,而并不要求提高精度,如抛光、砂光等。超精密加工：航天、激光、电子、核能等尖端技术领域中需要某些特别精密的零件，其精度高达IT4以上，表面粗糙度不大于 Ra 0.01微米。这就需要采取特殊措施进行超精密加工，如镜面车削、镜面磨削、软磨粒机械化学抛光等。 按表面形成方法区分切削加工时，工件的已加工表面是依靠切削工具和工件作相对运动来获得的。按表面形成方法，切削加工可分为 3类。刀尖轨迹法：依靠刀尖相对于工件表面的运动轨迹来获得工件所要求的表面几何形状，如车削外圆、刨削平面、磨削外圆、用靠模车削成形面等。刀尖的运动轨迹取决于机床所提供的切削工具与工件的相对运动。成形刀具法：简称成形法
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