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Production Automation
1.1.1 Automation Concepts
Automation may be defined as a system that is relatively safe-operating .Such a system includes complex mechanical and electronic devices and computer-based system that the place of observation,effort,and decision by a human operator. It is a system that exhibits properties of human being by following predetermined operations or responding to encoded instructions.
1.1.2 Computer process control
Process control involves the control of variables in a manufacturing process, where one or any combination of materials and equipment produces or modifies a product to make it more useful and hence more valuable. In process control controls continuous operations. Two kinds of control systems are the open loop and the closed loop.In an open-loop control system, the computer dose not itself automate the process .That is ,there is no self-correction.The process remains under the direct control of human operators,who read form various sources of information such as instruments, set calibrated dials for process regulation, and change the controlling medium.
Closed-loop control systems use computers to automate the process. He computer is directly in charge of the process. It sdjusts all controls form the information provided by sensing devices in the system to keep the process to the desired specifications, a technique that uses a feedback mechanism . Feedback is the action of measuring the difference between the actual result and the desired result and using that difference to drive the actual result toward the desired result. The term feedback comes forms from a measured sample of the output of the process (production) function that becomes the input of the control function . That is ,the output of the control function ,meeting special designed requirements is the input to the control system . Thus ,the signal begins at the output of the controlled production function and end at the input to the production.
Typical functions of process control systems are moonitoring ,data logging, quality control, maximizing profit for a given out put, supervisory control , and factory information systems (FIS). Benefits of computer process control system are increased productivity , improved product quality ,
and enhanced efficiency , safety , comfort ,and convenience.
1.1.3 Management Information Systems (MIS)
Management information systems are designed to aid in the performance of management functions.These systems are generated by computer systems and are developed to provide executives with up-to-the-minute information about the operations of the enterprise.When required, information systems are used to aid management in the decision-making functions of the enterprise . Viewing CIM (Computer Integrated Manufacturing) as an informations system for the enterprise for decision-making , CAPACS must be informations interconnected . As a result , there are many software packages associated with the CAPACS in Fig . 1 . 2 . Typical of there are CAPP , DCS , FIS and CAD .
The concept of an MIS is a design objective , its goal being to get the correct information to the appropriate manager at the right time . As a result , MIS implementation varies considerably among manufacturing enterprises because of each organization's function , type of production , informations resources available , and organizational commitment to MIS .
1.1.4 Engineering
Computer are used extensively in most engineering functions . Engineering is a profession in which a knowledge of the natural sciences is applied with judgment to develop ways of using the materials and forces of nature . Typical engineering functions using CAPACS are design , process planning , analysis and optimization , synthesis , evaluation and documentation , simulation , modeling , and quality control planning . Using CAPACS in engineering increases the productivity of engineers and improves the quality of designs .
For example ,the application of computers to an engineering design process is performed by a CAD system Engineers can design and thoroughly test concepts quickly and simply from one workstation . Computers permit engineers to take a concept from its original design through testing to numerical control (NC) output , or a combination of steps in between . They perform complex scientific and engineering computations rapidly with high accuracy , calculate physical properties before actual parts are made and provide a fast , easy method to create models of even the most complex parts .
The computer has influenced the way products are designed , documented and released for production . As technology develops , engineering operations are becomeing more and more automated and are relieving the engineer of many tedious manual calculations .
1.1.5 Production
Applications of computers to the production process encompass such functions as computer monitoring , supervisory computer control , direct digital control ( DDC) , material handing , product fabrication , assembly and test/inspection operations . New ideas and technology developments are gaining acceptance on the factory floor . More important , the integration of more computers into the production process increases automation on the factory floor .
Computer automation helps to organize , access , and provide vital information in a common date base system for use by all manufacturing operations . Computer automation helps to control and to schedule machines and process , and to control raw materials and parts . A computer automated system concept is shown in FIG . 1 . 3 . Each function in manufacturing has its own area controller under the control of a host computer in order to share information with other operations .
生產(chǎn)自動化
1.1.1自動化概念
自動化可以被定義為一個操作比較安全的系統(tǒng)。這個系統(tǒng)，包括復雜的機電設(shè)備和由一個人為操作員觀察、嘗試并決定其方位的電腦系統(tǒng)。它是一個按照事先確定的操作或應(yīng)對編碼指示來展現(xiàn)人的性能的系統(tǒng)。
1.1.2計算機過程控制?????
過程控制涉及到生產(chǎn)過程中的控制變量，在此生產(chǎn)過程中，一種或任意一種材料和設(shè)備聯(lián)合生產(chǎn)或修改產(chǎn)品，使其更加有用，因此更有價值。過程控制控制不間斷運行?？刂葡到y(tǒng)有兩種，即開環(huán)控制系統(tǒng)和閉環(huán)控制系統(tǒng)。在一個開環(huán)控制系統(tǒng)中，計算機本身不會使過程自動化。也就是說，沒有自我更正.這個過程仍然直接受控于人為操作員，他閱讀各種信息來源，如工具，建立校準盤的過程監(jiān)管，來改變控制的媒介。
閉環(huán)控制系統(tǒng)，使用計算機來實現(xiàn)過程自動化。電腦直接負責其過程。它根據(jù)傳感裝置所提供的信息對所有控制適時調(diào)整，以保持這一過程所需的規(guī)格及使用一個反饋機制的技術(shù)。反饋是衡量實際結(jié)果與期望的結(jié)果之間差異的行為，利用這種差異，以推動實際結(jié)果向所期望的結(jié)果的進展。期限反饋根據(jù)過程（生產(chǎn)）功能輸出的測量樣本而形成格式，進而轉(zhuǎn)為控制功能的輸入。也就是說，控制功能的輸出，如果滿足了特殊設(shè)計的要求即可轉(zhuǎn)變成控制功能的輸入。因此，信號始于控制生產(chǎn)功能輸出之時并結(jié)束于生產(chǎn)功能輸入之時。
過程控制系統(tǒng)的典型功能是操作，記錄數(shù)據(jù)，控制質(zhì)量，為某一輸出，監(jiān)控，和工廠信息系統(tǒng)（電）提供最大限度的好處 。計算機過程控制系統(tǒng)的優(yōu)點在于能夠提高生產(chǎn)率，改進產(chǎn)品質(zhì)量和提高效率，且安全，舒適和方便。
1.1.3 管理信息系統(tǒng)（ MIS ）
?????管理信息系統(tǒng)用來為管理功能的實施提供幫助。這些系統(tǒng)由計算機系統(tǒng)產(chǎn)生，并被用來為管理人員提供有關(guān)企業(yè)運作的最新信息。我們可用信息系統(tǒng)來幫助企業(yè)制定決策。例如，可把計算機集成制造（計算機集成制造）作為一個信息系統(tǒng)，為企業(yè)決策， CAPACS必須是相互關(guān)聯(lián)的信息。其結(jié)果是，有許多與CAPACS的圖1.2 相關(guān)的軟件包。典型的有 CAPP系統(tǒng)，集散控制系統(tǒng)，模糊推理系統(tǒng)和計算機輔助設(shè)計。
? 管理信息系統(tǒng)的概念是一個設(shè)計目標，其目的是在合適的時間，得到正確的信息并給適當?shù)慕?jīng)理。因此，制造企業(yè)之間各組織的功能，生產(chǎn)類型，信息資源及組織對 MIS的承諾，會造成系管理信息系統(tǒng)的實施不盡相同。
1.1.4工程?????
電腦被廣泛應(yīng)用在工程領(lǐng)域。工程學是一門職業(yè)，在這門職業(yè)中，我們可通過所獲取的自然科學知識加判斷識別力來形成使用材料和自然力量的方法。使用CAPACS的典型工程功能是設(shè)計，工藝規(guī)劃，分析和優(yōu)化，合成，評價和記錄，仿真，建模，和質(zhì)量控制規(guī)劃。工程使用CAPACS可以增加工程師的生產(chǎn)并提高設(shè)計質(zhì)量。
?? 例如，工程的設(shè)計過程使用計算機是由CAD系統(tǒng)的工程師負責的，他們能夠迅速而簡單地設(shè)計出來自工作站的方案并對其進行徹底檢驗。計算機允許工程師通過測試數(shù)字控制（數(shù)控）輸出，或者兩者之間的步驟，采用原來的設(shè)計方案。他們能迅速而精度地進行復雜的科學和工程計算，能在實際零部件被生產(chǎn)數(shù)之前計算出物理性能，并提供了一個快速，簡單的方法，用于建立模型，即使是最復雜的部分。
計算機已經(jīng)影響了產(chǎn)品設(shè)計，記錄和發(fā)布生產(chǎn)的方式。隨著技術(shù)的發(fā)展，工程業(yè)務(wù)也在廣泛采用自動化，給工程師減少了許多繁瑣的人工計算。
1 .1.5 生產(chǎn)?
?計算機應(yīng)用于生產(chǎn)過程有以下功能，包括監(jiān)測計算機，監(jiān)督計算機控制，直接數(shù)字控制（ DDC） ，材料處理，產(chǎn)品制造，組裝和測試/檢查行動。工廠車間也正在接受新的觀念和技術(shù)的發(fā)展。更重要的是，伴隨著更多的計算機被用到生產(chǎn)過程，工廠車間自動化程度加深了。
?????計算機自動化協(xié)助組織，存取，并提供資料庫中的重要信息，供所有的制造業(yè)務(wù)。計算機自動化控制，并幫助安排機器和過程，同時還可控制原材料和零部件。計算機自動化系統(tǒng)的概念圖.1.3.所示，在制造業(yè)領(lǐng)域，每種功能都會在主機電腦的控制之下行使自己的控制范圍，這樣方便了與其他操作共享信息。