CA6140車床撥叉[831008] 加工工藝及鉆2-φ20,φ50孔夾具設(shè)計【氣動夾具】版本3【含CAD+PDF圖紙】
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畢業(yè)論文(設(shè)計)開題報告題目名稱 CA6140車床831008撥叉零件數(shù)控加工工藝及工裝設(shè)計 學生姓名王曉宇專業(yè)機電技術(shù)教育班級042班指導教師姓名杜家熙專業(yè)機械制造職稱副教授完成期限2009年2月16日至2009年2月27日一、選題的目的意義隨著我國現(xiàn)代制造技術(shù)的發(fā)展,數(shù)控機床的普及和從事數(shù)控加工人員的增多,數(shù)控加工越來越受到人們的重視。撥叉是一種重要輔助零件,廣泛應用于我們的日常生活及生產(chǎn)當中,在機械行業(yè)有著越來越重要的作用,撥叉零件的制造精度能不能夠滿足加工技術(shù)要求;如何更大限度的降低機加工的基本勞動時間及提高單位時間內(nèi)的生產(chǎn)率,都成為機械行業(yè)勢待解決的技術(shù)性問題。隨著數(shù)控技術(shù)的不斷發(fā)展成熟及數(shù)控技術(shù)應用的不斷廣泛化、深入化、大眾化,我們意識到,采用數(shù)控機床來加工撥叉零件既能夠提高零件的精度又能夠完成采用普通機床加工時應運受限的瓶頸,對提高加工效率、以及降低勞動強度都有不可估量之好處。二、國內(nèi)外研究現(xiàn)狀隨著計算機科學、信息技術(shù)的迅速發(fā)展,傳統(tǒng)的制造業(yè)已發(fā)生了十分顯著的變化,發(fā)達國家正進行由傳統(tǒng)的制造技術(shù)向現(xiàn)代制造技術(shù)的轉(zhuǎn)變,并提出了全新的制造模式。數(shù)控加工技術(shù)將逐步引航現(xiàn)代機械制造業(yè)的發(fā)展。數(shù)控機床的應用范圍日益擴大,其產(chǎn)生的經(jīng)濟效益與社會效益十分明顯。尤其是數(shù)控加工不斷朝高速、精密方向的發(fā)展,提高數(shù)控機床的應用范圍對于提高制造企業(yè)的競爭力有著重要的意義。對傳統(tǒng)零件的數(shù)控加工技術(shù)也得到越來越廣泛的應用。面對新技術(shù)、新工藝的不斷出現(xiàn),提高數(shù)控加工技術(shù)在傳統(tǒng)撥叉類零件的應用也受到越來越多的重視。如何使數(shù)控技術(shù)在加工這一類零件中表現(xiàn)出其高質(zhì)量、高精度、高效率,都成為各國爭先要解決的問題。因此研究它對我國的制造行業(yè)很有借鑒作用。三、主要研究內(nèi)容1) 數(shù)控加工工藝的特點及說明;2) 數(shù)控加工的一般步驟;3) 撥叉零件數(shù)控加工工藝原理及特點;4) 撥叉在數(shù)控加工中的應用及其優(yōu)越性;5) 通過撥叉零件的工裝設(shè)計來體現(xiàn)數(shù)控加工的重要作用;四、畢業(yè)論文(設(shè)計)的研究方法或技術(shù)路線1. 根據(jù)設(shè)計內(nèi)容查閱相關(guān)期刊資料;2. 利用網(wǎng)絡(luò)查找相關(guān)資料進行修改整理;3. 對實際生產(chǎn)中撥叉零件沒的應用進行統(tǒng)計總結(jié);4. 論文總結(jié)。五、參考文獻與資料1 趙家奇. 機械制造工藝學課程設(shè)計指導書(2版). 北京:機械工業(yè)出版社,2006.2 曾志新,呂明. 機械制造技術(shù)基礎(chǔ). 武漢:武漢理工大學出版社,2001.3 李益明. 機械制造工藝設(shè)計簡明手冊. 北京:機械工業(yè)出版社,1993.4 肖詩綱. 切削用量手冊. 北京:機械工業(yè)出版社,1993.5 金屬切削機床夾具設(shè)計手冊. 上海柴油機廠工藝設(shè)備研究所編. 北京:機械工業(yè)出版社,1987.6 李旦,邵東向,王杰等. 機床專用夾具圖冊. 哈爾濱:哈爾濱工業(yè)大學出版社(2版),2005.7 羅良玲,劉旭波. 數(shù)控技術(shù)及應用. 北京:清華大學出版社,2005.8 邏輯. 數(shù)控工藝及刀具. 重慶:重慶大學出版社,2006.9 劉武發(fā),劉德平. 機床數(shù)控技術(shù). 北京:化學工業(yè)出版社,2007.10 劉萬菊. 數(shù)控加工工藝及編程. 北京:機械工業(yè)出版社,2007.11 余英良. 數(shù)控工藝與編程技術(shù). 北京:化學工業(yè)出版社,2007.12 楊建明. 數(shù)控加工工藝與編程. 北京:北京理工大學出版社,2006.13 賀曙新,張思第,文少波. 數(shù)控加工工藝. 北京:北京工業(yè)出版社,2005.14 聶秋根,陳光明. 數(shù)控加工實用技術(shù). 北京:電子工業(yè)出版社,2007.15 唐應謙. 數(shù)控加工工藝學. 北京:中國勞動保障出版社,2000.16 胡志剛. 計算機輔助繪圖. 北京:高等教育出版社,1999.17 趙家奇編. 機械制造工藝學課程設(shè)計指導書2版. 北京: 機械工業(yè)出版社,2000.18 李云主編. 機械制造及設(shè)備指導手冊. 北京: 機械工業(yè)出版社,1997.19 孟少農(nóng)主編. 機械加工工藝手冊. 北京: 機械工業(yè)出版社,1991.20 徐圣群主編. 簡明加工工藝手冊. 上海: 上??茖W技術(shù)出版社,1991.六、指導教師審批意見摘 要本設(shè)計分析研究了CA6140車床變速箱中拔叉零件的加工工藝規(guī)程及夾具設(shè)計。由于拔叉零件的結(jié)構(gòu)較為復雜,工序較多,因此為保證加工精度提高生產(chǎn)率及降低勞動強度,考慮采用數(shù)控機床進行加工,首先進行了撥叉零件工藝性分析、確定了工藝方案及加工順序,進行了撥叉零件數(shù)控加工工藝規(guī)程設(shè)計和鉆孔工序的夾具設(shè)計,為撥叉零件在數(shù)控機床上加工提供了理論依據(jù)和有效的硬件保證。 關(guān)鍵詞:數(shù)控加工工藝,定位,夾緊,專用夾具CA6140 Lathe 831008 Fork Parts CNC Machining Technology and Equipment DesignAbstractAnalysis of the design of the gearbox in the CA6140 lathe machining fork and Fixture Design Process.Fork parts as a result of the more complex the structure, process more, so in order to ensure the accuracy of processing to increase productivity and reduce labor intensity, consider the use of CNC machine tools for processing, first of all, a fork components analysis process to determine the technology solutions and processing order , a fork parts Process Design CNC machining and drilling of the fixture design process, fork parts for CNC machine tools in the processing provides a theoretical basis and an effective assurance of hardware.Keywords: NC Machining Process, Positioning, Clamping, Special Fixture目 錄 1 緒論 .1 2 數(shù)控加工工藝概述 .1 2.1 數(shù)控加工工藝分析的一般步驟與方法 .1 2.2 機床的合理選用 .1 2.3 數(shù)控加工零件工藝性分析 .2 2.3.1 零件圖樣上尺寸數(shù)據(jù)的給出應符合編程方便的原則 .2 2.3.2 零件各加工部位的結(jié)構(gòu)工藝性應符合數(shù)控加工的特點 .2 2.4 加工方法的選擇與加工方案的確定 .2 2.4.1 加工方法的選擇 .2 2.4.2 加工方案確定的原則 .3 2.5 工序與工步的劃分及加工順序安排 .3 2.5.1 工序的劃分 .3 2.5.2 工步的劃分 .3 2.5.3 加工順序安排 .4 2.6 零件的安裝與夾具的選擇 .4 2.6.1 定位安裝的基本原則 .4 2.6.2 選擇夾具的基本原則 .4 2.7 刀具的選擇與切削用量的確定 .4 2.7.1 刀具的選擇 .4 2.7.2 切削用量的確定 .5 2.8 對刀點與換刀點的確定 .5 2.9 加工路線的確定 .5 3 撥叉零件數(shù)控加工工藝分析 .6 3.1 撥叉零件的作用 .6 3.2 撥叉零件的工藝分析 .7 3.3 確定撥叉零件生產(chǎn)類型 .7 3.4 確定撥叉零件毛坯類型 .7 3.4.1 確定毛坯種類 .7 3.4.2 確定鑄件加工余量及形狀 .7 3.4.3 繪制鑄件零件圖 .8 3.5 撥叉零件數(shù)控加工工藝規(guī)程設(shè)計 .8 3.5.1 選擇定位基準 .8 3.5.2 制定數(shù)控加工工藝路線 .8 3.6 機械加工余量、工序尺寸及公差的確定 .9 3.6.1 圓柱表面工序尺寸 .9 3.6.2 平面工序尺寸 .10 3.6.3 確定切削用量及時間定額 .10 4 夾具設(shè)計 .19 4.1 問題的提出 .19 4.2 夾具設(shè)計 .19 4.2.1 定位基準選擇 .19 4.2.2 切削力及夾緊力計算 .20 4.3 定位誤差分析 .20 4.3.1 定位元件尺寸及公差的確定 .20 4.3.2 計算鉆套中心線與工作臺的垂直度誤差 .20 4.3.3 計算定位銷軸與工作臺的平行度誤差 .21 4.4 夾具設(shè)計及操作的簡要說明 .21 5 結(jié)束語 .23 致謝 .24 參考文獻 .25 撥叉零件的數(shù)控加工工藝及工裝設(shè)計,論文作者:王曉宇 學 號:20040315025 所在班級:機教042 指導老師:杜家熙,一:撥叉零件數(shù)控加工工藝簡述 隨著數(shù)控技術(shù)應用的不斷廣泛化、深入化、大眾化,為了提高傳統(tǒng)零件的的制造精度、提高勞動生產(chǎn)率及降低勞動強度,考慮采用數(shù)控加工來滿足其要求。 對于撥叉零件來說由于其形狀較復雜、加工工序較多,為提高加工效率,考慮采用數(shù)控機床進行加工。,二:撥叉的普通加工工序,工序01 粗銑20、50下端面,以T2為粗基準,采用X51立式銑床加專用夾具; 工序02 粗銑20上端面,以T1為定位基準,采用X51立式銑床加專用夾具; 工序03 粗銑50上端面,以T4為定位基準,采用X51立式銑床加專用夾具; 工序04 鉆、擴20孔,以32外圓和T2為基準,采用Z525立式鉆床加專用夾具; 工序05 粗鏜50孔,以D1為定位基準,采用T616臥式鏜床加專用夾具; 工序06 銑斜肩,以D1和T2為定位基準,采用X51立式銑床加專用夾具; 工序07 精銑20下端面,以T2為基準,采用X51立式銑床加專用夾具; 工序08 精銑20上端面,以T1為基準,采用X51立式銑床加專用夾具; 工序09 粗鉸、精鉸20孔,以T2和32外圓為基準,采用Z525立式鉆床加專用夾具; 工序10 精銑50端面,以D1為基準,采用X51立式銑床加專用夾具; 工序11 半精鏜50孔,以D1做定位基準,采用T616臥式鏜床加專用夾具; 工序12 鉆、鉸8錐孔,以T1和零件中線為基準,采用Z525立式鉆床加專用夾具; 工序13 鉆M6底孔,攻螺紋,以T1和零件中線為基準,采用Z525立式鉆床并采用專用夾具; 工序14 銑斷,以D1為基準,采用X60臥式銑床加專用夾具,撥叉的數(shù)控加工工序:,工序01 粗銑、精銑20、50下端面,以T2為粗基準,采用立式數(shù)控銑床加專用夾具; 工序02 粗銑、精銑20上端面,以T4為定位基準,采用立式數(shù)控銑床加專用夾具;粗銑、精銑50上端面,以T4為定位基準,采用立式數(shù)控銑床加專用夾具; 工序03 鉆、擴20孔,粗鉸、精鉸20孔;以32外圓和T2為基準,采用立式數(shù)控鉆床加專用夾具;粗鏜、半精鏜50孔,以D1為定位基準,采用臥式數(shù)控鏜床加專用夾具; 工序04 銑斜肩,以D1和T2為定位基準,采用立式數(shù)控銑床加專用夾具; 工序05 精銑50端面,以D1為基準,采用立式數(shù)控銑床加專用夾具; 工序06 鉆、鉸8錐孔,以T1和零件中線為基準,采用立式數(shù)控鉆床加專用夾具; 工序07 鉆M6底孔,攻螺紋,以T1和零件中線為基準,采用立式數(shù)控鉆床并采用專用夾具; 工序08 銑斷,以D1為基準,采用臥式數(shù)控銑床加專用夾具;,三:鉆、擴20孔,粗鉸、精鉸20孔,粗鏜、半精鏜50孔的數(shù)控加工時夾具的設(shè)計,圖一:撥叉零件圖,1).定為基準的選擇:,由零件圖可知,孔20、50為通孔,跟撥叉的上下底面有垂直度的技術(shù)要求要求,為使定位誤差為零,應該選擇撥叉下底面為定位基準保證該垂直度要求。此外,還應以20孔外圓柱面為基準,從而保證孔在精度要求。 為了提高加工效率,現(xiàn)決定采用自動夾緊工件快換裝置,并采用快換鉆套以利于在鉆底孔后進行精鉸或精鏜。,2).夾緊力的計算:,(1)鉆20時的夾緊力 由實際加工的經(jīng)驗可知,鉆削時的主要切削力為鉆頭的切削方向,即垂直于工作臺,查切削手冊表2.3,切削力計算公式為: 其中: , , , , , 與加工材料有關(guān),取0.94;與刀具刃磨形狀有關(guān),取1.33;與刀具磨鈍標準有關(guān),取1.0,則:,(2)鉆50孔時的夾緊力,由實際加工的經(jīng)驗可知,鉆削時的主要切削力為鉆頭的切削方向,即垂直于工作臺,查切削手冊表2.3,切削力計算公式為: 其中: , , , , , 與加工材料有關(guān),取0.94;與刀具刃磨形狀有關(guān),取1.33;與刀具磨鈍標準有關(guān),取1.0,則:,由實際加工的經(jīng)驗可知,鉆削時的主要切削力為鉆頭的切削方向,即垂直于工作臺,查切削手冊表2.3,切削力計算公式為: 其中: , , , , , 與加工材料有關(guān),取0.94;與刀具刃磨形狀有關(guān),取1.33;與刀具磨鈍標準有關(guān),取1.0,則:,3):夾具體的設(shè)計,圖二 : 夾具體,4):夾具體的設(shè)計,圖三 : 夾具體,5)夾具裝備圖的設(shè)計:,圖四 : 裝備圖,由于能力有限,設(shè)計中有錯誤和不妥之處,敬請各位老師批評指正。 謝謝!,河南科技學院2009屆本科畢業(yè)論文(設(shè)計)外文資料學生姓名:王曉宇 所在院系:機電學院所學專業(yè):機電技術(shù)教育導師姓名:杜家熙完成時間:2009年3月27日Network architecturesThe term architecture is commonly used today to describe networks. A network architecture, such as illustrated in Fig.1.7, describes the components in the network, how they operate , and what form they take . A network encompasses hardware, software, data link controls (DLC), Standards, topology, and protocols.1. hardwareThe physical equipment in the network is referred to as the hardware. Typical of such equipment are computers, modems, telephone, terminals , machines, controllers, and the like.2. SoftwareSoftware consists of programs, procedures, and sometimes, associated documentation of the operation of the communication system. Communications software (CSW), application programs (AP), network control programs (NCP), operating system (OS), and database management system (DBMS) are examples of software.3. ProtocolsA protocol defines how network components establish communications, exchange data, and terminate communications. A protocol is essentially a formal set of conventions, or rules, between communicating processes about of messages to be exchanged. Handshaking and line discipline are also protocols. To make implementation and usage more convenient in sophisticated networks, higher-level protocols may use lower-level in a layered fashion.4. Data link controls A data link consists of electronic equipment such as electronic devices, terminals, and machines and the interfacing circuits that are operating in a particular way to permit information to be exchanged between installations. The specific method of operation is defined by transmission codes, transmission modes, and direction control.There are two major categories link control protocol in use today:(1) Asynchronous, in which bit streams are transferred at fixed rates with the transmitter and receiver operating in synchronization by the clock. (2)The flow of date to and from the many points and links within the network must be controlled and orderly. The sending and receiving sites must sequencing of the messages being transmitted among all users. The connection path between sits is usually shared by more than one user, as multipoint configuration. A multi-point line, sometimes called a multi-drop line, is a communications line having several subsidiary controllers that share time on the line under the control of a central site.Date line controls provide for all these needs. They manage the flow of data messages across the communications path, or links. In essence, they are special kinds of protocols consisting of a combination of software and hardware located at each site in the network. Through a communication link, the DLC protocol pro-vides for the reliable interchange of information between data terminal equipment. Typical DLC functions in the network are the following:Synchronizing the sender and receiver 1) Controlling the sending and receiving of data2) Detecting and recovering transmission errors between two points3) Maintaining awareness of link conditions4) Topologies Topology describes the surface layout the elements comprising the communications network-that is, it is the shape of the system. Communication system may be implemented in a variety of ways. typical communication system are telephone lines, radio wave links, networks, serial connections, parallel connections and power line system modulations. The choice of topology depends on factors such as cost, response time, throughput, capacity, load sharing, and capacity needs.5. Local area networksA local area network (LAN) is a communications network operating in a local area. It extends from several hundred to several thousand feet within a building or other facility. A LAN is owned and operated by an individual or organization and is, therefore, not subject to regulation by either the federal communications commission (FCC) or the state Public Utility Commission (PUS). A LAN is a means of connecting various types of equipment for the purpose of sharing resources and communicating in a distributed processing environment, as illustrated in fig .1.8. that is , all device that must communicate with one another in a CIM environment can be tied together though some form of common interface such as a LAN .An effective LAN has specific characteristics. Typical of these are the following: Is in a moderate-sized geographic area (office, laboratory, building, factory, industrial complex, or campus, for example) Has medium to high sped data channel(s) Provides reliable communications Is owned and used by a single organization Connects independent devices rather than a device and its peripherals A LAN usually has four major components that serve to transport data between end users: user workstation, protocol control logic. medium interface, and physical path.6. User workstationThe user workstation is used to accomplish an application. The station can be anything from a word processor to a mainframe computer.(1) Protocol control logic A protocol control logic takes user is information and converts it to a protocol that can move the LAN network to reach the desired location , the protocol logic also controls the LAN and provides for the end user is access to the network .(2) Medium InterfaceThe medium interface function generates the electrical signals to be transmitted on the LAN the interface is between the path the protocol logic can take several forms, typical of which are CATV (cable television) taps , infrared diodes for infrared path , microwave antennas, or complex laser-emitting semiconductors for optic fibers.(3) Physical Path A LAN is path may consist of coaxial TV cables, coaxial bade-band cables, twisted pair of wires, optic fibers, and microwaves. Cable TV coaxial cable is used in many networks because it has a high capacity, a very good signal-to-noise ratio, low signal radiation, and low error rates.(4) Manufacturing Automation ProtocolThere are many types and sizes of networks. Some LAN systems are owned by an organization and are confined to the premise of that organization. Others are owned by national or international public networks that may be accessed by the user. In many case, LAN systems may also connect to public networks and be able to access them.Network are also connected in several configurations (topologies) , as seeing in Fig .1.9.Each topology can constitute an entire network or can be just a portion of a large network .A star network is a centralized network in which each device is connected virtually to a central controlling point.A ring network, sometimes called a loop, is a network in which each device is connected to the next in sequence in a closed, circular fashion. This topology has two possible paths, one in each direction.A bus network is a topology that consists of a single shared line to which all devices are connected.In a hierarchy network, a central root node has over the entire network. The secondary nodes attached to the root can be front-end processors (EEP) that in turn connect to tertiary nodes of lesser significance. The hierarchy can consist of a large computer that has overall of several smaller control devices connected to their own terminals.A multiply connected topology requires that there be at least two paths between any pair of nods to assure availability and reliability m the event of failure one path or node.The unconstrained network occurs most commonly. The term unconstrained merely means that the configuration is not restricted to one specific kind of connection.Many LAN systems are available today. All use either base-bands, broad-bands, or both, in a base-band, the line is pulsed, as in the on/off conditions. Because these pulses are still the square wave direct current, they require no additional special handling or modulation, which makes the process relatively inexpensive, it is impossible to mix voice and data unless the analog voice signals have been previously digitized. The broadband technology requires a conversion process and is therefore more expensive. The advantages gained are that voice, video, and data can all be sent on the same channels. Facilities can be shared through assignment of frequency channels to allow all devices to operate simultaneously. Popular modulation and multiplexing techniques can be used because a wide range of frequencies is available. 4河南科技學院2009本科畢業(yè)論文(設(shè)計)外文資料翻譯學生姓名:王曉宇所在院系:機電學院所學專業(yè):機電技術(shù)教育導師姓名:杜家熙完成時間:2009年3月27日網(wǎng)絡(luò)建筑學現(xiàn)在在今天,建筑學這個術(shù)語通常用來描述網(wǎng)絡(luò)系統(tǒng)。例如圖表1.7所示的,建筑描述了一個網(wǎng)絡(luò)的各個組成部分他們之間是如何的操作以及以一種什么方式進行連接的。一個網(wǎng)絡(luò)系統(tǒng)包括硬件、軟件、數(shù)據(jù)線控制端、技術(shù)規(guī)范和數(shù)據(jù)傳輸?shù)膮f(xié)議。1、 硬件網(wǎng)絡(luò)系統(tǒng)中的物理組成部分叫做硬件;電腦、調(diào)制解調(diào)器、電話機、接線端、機器、控制端等等是這種設(shè)備的典型。2、 軟件軟件包括一系列程序、步驟,有時還有通訊系統(tǒng)操作的相關(guān)文檔。通訊軟件CSW、應用程序AP、網(wǎng)絡(luò)控制程序NCP、操作系統(tǒng)OS和數(shù)據(jù)庫管理系統(tǒng)DBMS是軟件的例子。3、 指令指令規(guī)定網(wǎng)絡(luò)系統(tǒng)各個組成部分是如何的建立通訊、傳輸數(shù)據(jù)和停止通訊的。實際上,一條指令是在通訊過程中關(guān)于信息被交換的形式和內(nèi)容的一系列的習慣或規(guī)則。轉(zhuǎn)移和排準則也是指令。為了使執(zhí)行和運用在復雜的網(wǎng)絡(luò)系統(tǒng)中更方便,高級指令可以用同一級的低級指令來實現(xiàn)。4、 數(shù)據(jù)連接控制一個數(shù)據(jù)連接有允許以數(shù)字化的形式自動傳輸信息的電子設(shè)備組成。他是一個安裝的裝備的集合,比如說:電子設(shè)備、終端機器和那些一特殊方式運行的允許信息在不同的設(shè)備之間被交換的界面電路。這種運行的特殊方式被界定為傳輸密碼、傳輸方式和反方向控制。在今天使用的主要有兩種連接控制協(xié)議:(1) 異步的方式,用這種方式小的數(shù)據(jù)流被一定和接受以一種異步比率。(2) 同步的方式,小的數(shù)據(jù)流被移動以一種固定的比率隨著時間轉(zhuǎn)換和接收操作同步進行。數(shù)據(jù)在網(wǎng)絡(luò)系統(tǒng)之中的很多點和線之間的傳輸流動可以被控制和排序。反發(fā)送和接收站必須了解在所有的用戶間被翻譯的信息的辨認行為和序列站一站之間的連接線路,像多點格局一樣,通常被多個用戶共同使用。多點連接有時又稱之為復合連接是在中心站控制下有若干個在連接上共享時間的補充控制者的一種交流。數(shù)據(jù)連接控制為下列所有的需要提供服務(wù),他們管理者數(shù)據(jù)信息在交流通路或連接之間的流動。實質(zhì)上,他們是本網(wǎng)絡(luò)系統(tǒng)中各個站點中的軟件和硬件聯(lián)合而構(gòu)成的特殊種類指令。通過交流鏈接,數(shù)據(jù)連接指令在數(shù)據(jù)接線端設(shè)備之間提供可靠的內(nèi)部交流信息,在網(wǎng)絡(luò)系統(tǒng)中數(shù)據(jù)控制的典型作用如下:1) 使和接收同步進行;2) 控制數(shù)據(jù)的發(fā)送和接收;3) 檢測和改善點與點之間的翻譯誤差;4) 布局。布局描述了構(gòu)成通訊網(wǎng)絡(luò)系統(tǒng)的各個單元的表面規(guī)劃,也就是說,是網(wǎng)絡(luò)系統(tǒng)的外形。通訊系統(tǒng)可以由很多方法實現(xiàn)。典型的通訊系統(tǒng)是電話連接、無線電連接、網(wǎng)絡(luò)系列連接、并列連接和電源連接一同調(diào)整。布局的選擇取決于,比如,成本、反應時間、生產(chǎn)量、電容、承載量和生產(chǎn)量需求等因素。5、 局域網(wǎng)局域網(wǎng)是在局部地區(qū)操作的網(wǎng)絡(luò)系統(tǒng),它在建筑物或其他設(shè)備中由幾百英尺擴展到幾千英尺。局域網(wǎng)是由私人或組織團體擁有和操作的。因此,它不是由聯(lián)邦通訊委員會和國家公共事業(yè)控制的項目。局域網(wǎng)是為了在一個緩緩前進的環(huán)境里邊共享資源和交流的目的而連接各種類型的設(shè)備的一種工具正如圖表1.8所示。也就是說,所有的裝置必須在一個能夠有連接在一起的通過一個常用形式的通訊口接收的界面環(huán)境和其他的相交流,像局域網(wǎng)。一個有效的局域網(wǎng)有一些具體的特點,典型的是以下這些: 在中型的地理地區(qū),辦公實驗室,建筑物、工廠、工業(yè)綜合體、校園等。 有中高速的數(shù)據(jù)傳輸頻道。 提供可靠的交流。 被當各機構(gòu)擁有和使用。 以獨立的裝置相連接,而不是一個裝置和它的外圍設(shè)備。通常有四個主要的部分在眾多的用戶之間運輸數(shù)據(jù)服務(wù)于局域網(wǎng)。比如說,用戶工作站、協(xié)議控制邏輯、中等的界面和物理通路。6、用戶工作站用戶工作站是用來完成一個申請,這個工作站可以是一個信息處理器到電腦主機的任何東西。(1) 協(xié)議控制邏輯協(xié)議控制邏輯接收用戶的信息并且把它轉(zhuǎn)換成可以在局域網(wǎng)間相互移動以達到渴望未知的協(xié)議,它也可以控制局域網(wǎng),為用戶提供機會接近網(wǎng)絡(luò)。(2) 中等界面中等界面的功能使電子信息在局域網(wǎng)上被傳輸位于路徑和協(xié)議控制邏輯中間的界面有好幾種形式,典型的像有線電視的旋塞,紅外線路徑的二極管微波天線和復雜的能散發(fā)激光的視覺光纖的半導體。(3) 物理通路局域網(wǎng)的路徑包含有線電視,有線電視的光纜被用在許多網(wǎng)絡(luò)里,因為它有局性能、好的信號噪比性、低信號輻射和低錯誤比。(4) 制造自動化協(xié)議這有很多類型和大小的網(wǎng)。一些局域網(wǎng)系統(tǒng)被一個機構(gòu)所擁有被限制在那個機構(gòu)的前提下,國家的或全球的公共網(wǎng)絡(luò)擁有它們的被用戶接近在多數(shù)情況下,局域網(wǎng)可能也和公共網(wǎng)絡(luò)連接,人們可以接近。網(wǎng)絡(luò)也被鏈接用幾種布局,正如在1.9的圖片中看到一樣,每一種布局能組成一個完整的網(wǎng)絡(luò)或僅僅是一個大型網(wǎng)絡(luò)的一部分。一個星狀網(wǎng)絡(luò)是一個中心網(wǎng)絡(luò),在這個網(wǎng)絡(luò)里面,每一個裝置實質(zhì)上都和控制點相連接。一個圓狀網(wǎng)絡(luò)有時又被稱為環(huán),在這個網(wǎng)絡(luò)里面,每一個裝置都按照順序和下一個相連接以一種封閉的迂回方式,這個布局有兩種可能的路徑,每一種朝一個方向。一個公共汽車網(wǎng)絡(luò)是這樣一個布局,所有的裝置和單個共享的線相連接。在一個等級森嚴的網(wǎng)絡(luò)組織網(wǎng)絡(luò)中心的根部節(jié)點已經(jīng)控制了整個網(wǎng)絡(luò),次要結(jié)點和前面結(jié)束處理器和根部節(jié)點連接,它反過來又和地位稍低的第三個結(jié)點相連接。等級森嚴的網(wǎng)絡(luò)組織由幾個大的電腦組成,它從整個控制幾個小的控制裝置并和它們各自的終端相連接。一個使用乘法連接的布局要求在任何一對節(jié)點中間兩條路徑,即如果一條路徑或節(jié)點發(fā)生錯誤的話,確信它 可以利用和可靠。不帶有強制性的網(wǎng)絡(luò)很常見了,詞條不帶有強迫性不僅僅意味著布局不被限制在具體的某一種連接上。今天許多局域網(wǎng)是可以的,所有使用基帶、寬頻或者兩個在基帶線在開關(guān)條件搏動。因為這些脈沖仍然是矩形直流電,他們不需要額外的處理或調(diào)整就能使過程相對廉價,除非類似的聲音信號從以前已經(jīng)被數(shù)字化,那么聲音和數(shù)據(jù)是不可能混合的。寬帶技術(shù)需要一個轉(zhuǎn)化過程,因此更加昂貴,獲得好處是聲音,視頻和數(shù)據(jù)都可以在同一個通道被發(fā)送。設(shè)備通過允許所有設(shè)備同時操作的頻率通道的協(xié)議被共同使用,因為頻率可以廣泛的變化、流行調(diào)頻和多屏幕放映技術(shù)是可以使用的。4
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