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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：盧曉志 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2月27日 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 . 5