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1、Numerical Control System The 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
2、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 inte
3、rface 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
4、 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 compl
5、ex 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. T
6、hese 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 appli
7、es 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
8、 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 princ
9、iple 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;
10、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 clos
11、ed-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 c
12、ommunication 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
13、 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
14、 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
15、 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
16、 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
17、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 structure In a single-microprocessor structure, only a microprocessor to focus on control
18、, 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 syste
19、ms 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
20、. 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 setting
21、s 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 procedure
22、s It 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 da
23、ta processing program, including input, decoding and data processing three elements. (2)Computing interpolation procedures CNC 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
24、 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
25、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 procedures Speed control program accor
26、ding 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 pr
27、ocedures 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
28、. (5)Diagnostic procedures Diagnostic 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 t
29、hat 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 cutti
30、ng 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.
31、 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
32、 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 too
33、ls 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, t
34、hread processing, ultra-precision machining, bench and scrapers and so on. By material removal rate and machining accuracy distinction can be divided into: ① 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, roug
35、h 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. ② Semi-finishing: General roughing and finishing as the middle between the process, but the work piece accuracy and surfac
36、e roughness on the less demanding position, but also can be used as the final processing. ③ 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 proc
37、ess. ④ 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. ⑤ Modification process: the aim is to reduce t
38、he surface roughness, to improve the corrosion, dust properties and improve appearance, but does not require higher precision, such as polishing, sanding, etc. ⑥ ultra-precision machining: aerospace, lasers, electronics, nuclear energy and other cutting-edge technologies that need some special preci
39、sion 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
40、 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. ① tip trajectory method: relying on the tip relative to the trajectory of the surface to obtain the required work piece surface geo
41、metry, 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. ② forming tool method: short forming method, with the final work piece su
42、rface 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 manuf
43、acture 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. ③ generating method: also known as rotary cutting method, cutting tool and work piece during pr
44、ocessing 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, g
45、ear 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 technolog
46、y, 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
47、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 Controller A. Power PLC
48、s 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 d
49、irectly 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 statu
50、s, 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 Pr
51、ovisions 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 sto
52、pped. 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 m
53、emory. 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.
54、 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 co
55、unting, positioning modules. F.Communication module Such as Ethernet, RS485, Prefab’s-DP communication module. 數(shù)控系統(tǒng) 數(shù)控系統(tǒng)是數(shù)字控制系統(tǒng)簡稱,英文名稱為Numerical Control System,早期是由硬件電路構成的稱為硬件數(shù)控(Har
56、d NC),1970年代以后,硬件電路元件逐步由專用的計算機代替稱為計算機數(shù)控系統(tǒng)。 計算機數(shù)控(Computerized numerical control,簡稱CNC)系統(tǒng)是用計算機控制加工功能,實現(xiàn)數(shù)值控制的系統(tǒng)。CNC系統(tǒng)根據(jù)計算機存儲器中存儲的控制程序,執(zhí)行部分或全部數(shù)值控制功能,并配有接口電路和伺服驅(qū)動裝置的專用計算機系統(tǒng)。 CNC系統(tǒng)由數(shù)控程序、輸入裝置、輸出裝置、計算機數(shù)控裝置(CNC裝置)、可編程邏輯控制器(PLC)、主軸驅(qū)動裝置和進給(伺服)驅(qū)動裝置(包括檢測裝置)等組成。 CNC系統(tǒng)的核心是CNC裝置。由于使用了計算機,系統(tǒng)具有了軟件功能,又用PL
57、C代替了傳統(tǒng)的機床電器邏輯控制裝置,使系統(tǒng)更小巧,其靈活性、通用性、可靠性更好,易于實現(xiàn)復雜的數(shù)控功能,使用、維護也方便,并具有與上位機連接及進行遠程通信的功能。 目前世界上的數(shù)控系統(tǒng)種類繁多,形式各異,組成結構上都有各自的特點。這些結構特點來源于系統(tǒng)初始設計的基本要求和工程設計的思路。例如對點位控制系統(tǒng)和連續(xù)軌跡控制系統(tǒng)就有截然不同的要求。對于T系統(tǒng)和M系統(tǒng),同樣也有很大的區(qū)別,前者適用于回轉體零件加工,后者適合于異形非回轉體的零件加工。對于不同的生產(chǎn)廠家來說,基于歷史發(fā)展因素以及各自因地而異的復雜因素的影響,在設計思想上也可能各有千秋。例如,美國Dynapath系統(tǒng)采用小板結構,便
58、于板子更換和靈活結合,而日本FANUC系統(tǒng)則趨向大板結構,使之有利于系統(tǒng)工作的可靠性,促使系統(tǒng)的平均無故障率不斷提高。然而無論哪種系統(tǒng),它們的基本原理和構成是十分相似的。 一般整個數(shù)控系統(tǒng)由三大部分組成,即控制系統(tǒng),伺服系統(tǒng)和位置測量系統(tǒng)。控制系統(tǒng)按加工工件程序進行插補運算,發(fā)出控制指令到伺服驅(qū)動系統(tǒng);伺服驅(qū)動系統(tǒng)將控制指令放大,由伺服電機驅(qū)動機械按要求運動;測量系統(tǒng)檢測機械的運動位置或速度,并反饋到控制系統(tǒng),來修正控制指令。這三部分有機結合,組成完整的閉環(huán)控制的數(shù)控系統(tǒng)。 控制系統(tǒng)主要由總線、CPU、電源、存貯器、操作面板和顯示屏、位控單元、可編程序控制器邏輯控制單元以及數(shù)據(jù)輸入
59、/輸出接口等組成。最新一代的數(shù)控系統(tǒng)還包括一個通訊單元,它可完成CNC、PLC的內(nèi)部數(shù)據(jù)通訊和外部高次網(wǎng)絡的連接。伺服驅(qū)動系統(tǒng)主要包括伺服驅(qū)動裝置和電機。位置測量系統(tǒng)主要是采用長光柵或圓光柵的增量式位移編碼器。 數(shù)控系統(tǒng)的硬件由數(shù)控裝置、輸入/輸出裝置、驅(qū)動裝置和機床電器邏輯控制裝置等組成,這四部分之間通過I/O接口互連。 數(shù)控裝置是數(shù)控系統(tǒng)的核心,其軟件和硬件來控制各種數(shù)控功能的實現(xiàn)。 數(shù)控裝置的硬件結構按CNC裝置中的印制電路板的插接方式可以分為大板結構和功能模塊(小板)結構;按CNC裝置硬件的制造方式,可以分為專用型結構和個人計算機式結構;按CNC裝置中微處理器的
60、個數(shù)可以分為單微處理器結構和多微處理器結構。 ?。?)大板結構和功能模板結構 1)大板結構 大板結構CNC系統(tǒng)的CNC裝置由主電路板、位置控制板、PC板、圖形控制板、附加I/O板和電源單元等組成。主電路板是大印制電路版,其它電路板是小板,插在大印制電路板上的插槽內(nèi)。這種結構類似于微型計算機的結構。 2)功能模塊結構 (2)單微處理器結構和多微處理器結構 1)單微處理器結構 在單微處理器結構中,只有一個微處理器,以集中控制、分時處理數(shù)控裝置的各個任務。 2)多微處理器結構 隨著數(shù)控系統(tǒng)功能的增加、數(shù)控機床的加工速度的提高,單微處理
61、器數(shù)控系統(tǒng)已不能滿足要求,因此,許多數(shù)控系統(tǒng)采用了多微處理器的結構。若在一個數(shù)控系統(tǒng)中有兩個或兩個以上的微處理器,每個微處理器通過數(shù)據(jù)總線或通信方式進行連接,共享系統(tǒng)的公用存儲器與I/O接口,每個微處理器分擔系統(tǒng)的一部分工作,這就是多微處理器系統(tǒng)。 CNC軟件分為應用軟件和系統(tǒng)軟件。CNC系統(tǒng)軟件是為實現(xiàn)CNC系統(tǒng)各項功能所編制的專用軟件,也叫控制軟件,存放在計算機EPROM內(nèi)存中。各種CNC系統(tǒng)的功能設置和控制方案各不相同,它們的系統(tǒng)軟件在結構上和規(guī)模上差別很大,但是一般都包括輸入數(shù)據(jù)處理程序、插補運算程序、速度控制程序、管理程序和診斷程序。 (1)輸入數(shù)據(jù)處理程序
62、它接收輸入的零件加工程序,將標準代碼表示的加工指令和數(shù)據(jù)進行譯碼、數(shù)據(jù)處理,并按規(guī)定的格式存放。有的系統(tǒng)還要進行補償計算,或為插補運算和速度控制等進行預計算。通常,輸入數(shù)據(jù)處理程序包括輸入、譯碼和數(shù)據(jù)處理三項內(nèi)容。 ?。?)插補計算程序 CNC系統(tǒng)根據(jù)工件加工程序中提供的數(shù)據(jù),如曲線的種類、起點、終點等進行運算。根據(jù)運算結果,分別向各坐標軸發(fā)出進給脈沖。這個過程稱為插補運算。進給脈沖通過伺服系統(tǒng)驅(qū)動工作臺或刀具作相應的運動,完成程序規(guī)定的加工任務。 CNC系統(tǒng)是一邊插補進行運算,一邊進行加工,是一種典型的實時控制方式,所以,插補運算的快慢直接影響機床的進給速度,因此應該盡
63、可能地縮短運算時間,這是編制插補運算程序的關鍵。 (3)速度控制程序 速度控制程序根據(jù)給定的速度值控制插補運算的頻率,以保預定的進給速度。在速度變化較大時,需要進行自動加減速控制,以避免因速度突變而造成驅(qū)動系統(tǒng)失步。 (4)管理程序 管理程序負責對數(shù)據(jù)輸入、數(shù)據(jù)處理、插補運算等為加工過程服務的各種程序進行調(diào)度管理。管理程序還要對面板命令、時鐘信號、故障信號等引起的中斷進行處理。 (5)診斷程序 診斷程序的功能是在程序運行中及時發(fā)現(xiàn)系統(tǒng)的故障,并指出故障的類型。也可以在運行前或故障發(fā)生后,檢查系統(tǒng)各主要部件(CPU、存儲器、接口、開關、伺服系統(tǒng)等)的功
64、能是否正常,并指出發(fā)生故障的部位。 切削加工 任何切削加工都必須具備3個基本條件:切削工具、工件和切削運動。切削工具應有刃口,其材質(zhì)必須比工件堅硬。不同的刀具結構和切削運動形式構成不同的切削方法。用刃形和刃數(shù)都固定的刀具進行切削的方法有車削、鉆削、鏜削、銑削、刨削、拉削和鋸切等;用刃形和刃數(shù)都不固定的磨具或 磨料進行切削的方法有磨削、研磨、珩磨和拋光等。 切削加工是機械制造中最主要的加工方法。雖然毛坯制造精度不斷提高,精鑄、精鍛、擠壓、粉末冶金等加工工藝應用日廣,但由于切削加工的適應范圍廣,且能達到很高的精度和很低的表面
65、粗糙度,在機械制造工藝中仍占有重要地位?!〗饘俨牧系那邢骷庸び性S多分類方法。常見的有以下3種。 按工藝特征區(qū)分 切削加工的工藝特征決定于切削工具的結構以及切削工具與工件的相對運動形式。按工藝特征,切削加工一般可分為:車削、銑削、鉆削、鏜削、鉸削、刨削、插削、拉削、鋸切、磨削、研磨、珩磨、超精加工、拋光、齒輪加工、蝸輪加工、螺紋加工、超精密加工。按材料切除率和加工精度區(qū)分 可分為:①粗加工:用大的切削深度,經(jīng)一次或少數(shù)幾次走刀從工件上切去大部分或全部加工余量,如粗車、粗刨、粗銑、鉆削和鋸切等,粗加工加工效率高而加工精度較低,一般用作預先加工,有時也可作最終加工。②半精加工:一般作為粗加工與精
66、加工之間的中間工序,但對工件上精度和表面粗糙度要求不高的部位,也可以作為最終加工。③精加工:用精細切削的方式使加工表面達到較高的精度和表面質(zhì)量,如精車、精刨、精鉸、精磨等。精加工一般是最終加工。④精整加工:在精加工后 進行,其目的是為了獲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。⑤修飾加工:目的是為了減小表面粗糙度,以提高防蝕、防塵性能和改善外觀,而并不要求提高精度,如拋光、砂光等。⑥超精密加工:航天、激光、電子、核能等尖端技術領域中需要某些特別精密的零件,其精度高達IT4以上,表面粗糙度不大于 Ra 0.01微米。這就需要采取特殊措施進行超精密加工,如鏡面車削、鏡面磨削、軟磨粒機械化學拋光等。 按表面形成方法區(qū)分切削加工時,工件的已加工表面是依靠切削工具和工件作相對運動來獲得的。按表面形成方法,切削加工可分為 3類。①刀尖軌跡法:依靠刀尖相對于工件表面的運動軌跡來獲得工件所要求的表面幾何形狀,如車削外圓、刨削平面、磨削外圓、用靠模車削成形面等。刀尖的運動軌跡取決于機床所提供的切削工具與工件的相對運動。②成形刀具法:簡稱成形法
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