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Experience in Industrial Control
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Andon System for Auto Industry 1.Overview Andon, or called ¡°dark light¡±, is a transliteration of Japanese. It means ¡°light¡± or ¡°lantern¡± in Japanese.Now Andon system means not only ¡°light¡±, but also a set of professional information system in the management of auto production line, which includes flexible automation quality control, material supply management and manufacturing information management. This system can display the real-time status of equipment, product quality, material flow and other manufacturing information in the production line and control the production quality and in-time material supply to keep balanced production. This production management pattern is very popular in US, Germany and Japan. Andon system has become a universal system in the automobile industry, widely applied to overall installation, lacquer, bodywork, punch and power assembly these four major workshops. With the reform and opening up of China and internationalization of automobile industry, multinational corporations has accelerated the rate of cooperation with Chinese automobile industry and the rate of assets recombination, joint product development and joint market domination. However, because our automobile industry, especially the automobile technology is mainly relied on multinational corporations, Chinese automobile industry faces great competitive pressure. In order to keep competitive, corporations should introduce technology and equipment and introduce advanced manufacturing management idea and pattern. In this way, they can improve the product quality and quantity in maximum and reduce production costs so that corporation can survive in the fierce competition. Shanghai General Motors has fully realized this point, and as a result, it installed Andon system developed by foreign company in the initial stages of its establishment. During that time, the Andon system was very expensive and its technology was monopolized by foreign companies. In early 2000, Shanghai General Motors invited multinational companies to bid for Andon system and invited several domestic IT companies at the same time. Companies that were engaged in the bidding include GE FUNAG, HADEN, Japanese Dafuke Corporation, TKS Corporation and TRINITY Co., Ltd. Through strict selection and fierce competition, our corporation won the bidding at last with the best plan and the lowest price. With these years¡¯ effort, our Andon system has covered a lot of workshops of Shanghai General Motors, such as bodywork, power assembly, punch workshops, the overall installation, bodywork, lacquer workshops of the south factory and the bodywork and lacquer workshops of Shanghai Dongyue General Motors. This system not only fills the gap in this field for domestic companies, but also has technical innovations. Compared to overseas Andon systems, its technology and costs are very competitive. 2.Functions Andon system has three main functions: quality control, material supply and production management.If there is a quality problem in a certain station of the production line, operators just need to pull the quality-pull. The Andon board will display the request from the certain station and play relevant music so that engineers can receive the request and solve the problem in a short time. When the problem has been solved, operators just need to pull the quality-pull to reset and delete the request on the Andon board. If automobiles reach the fixed stop at the end of the station, however the problem has not been solved yet. Andon system will stop the production line to leave the problem in the certain station instead of leaving it to the next station. The request on the Andon board will not be deleted and the production line will not continue, unless the problem has been solved and the quality-pull has been pulled again. If automobiles reach the fixed stop at the end of the station, however certain parameter of QCOS still hasn¡¯t met the workmanship standard. Andon board will display the request of certain station and play the relevant music to stop the production line. The request will not be deleted and the production line will not continue, unless the parameter has met the standard. Andon system has achieved delicate production¡ª¡°do not create defect, do not pass on defect and do not allow defect¡±. When materials are needed, operators can push the button in time. Then Andon system will send the signal of material supply so that staff can send materials in time. The system will record the material transport information and gather it into the factory logistics database to realize automatic logistics management. Andon system can call the material management staff to check the material supply at fixed time to ensure the continuity of production. Andon system can manage and control the timetable. When it is time for work, rest, meal or leave, its screen will display relevant information and play relevant music. It can control the operation of production line automatically according to its workmanship. Andon system can collect and gather the required information about manufacturing and equipment so that supervisors and operators can see the manufacturing and equipment status clearly. It helps to control the manufacturing pace and analyze the reasons and causes of failure and the rationalization of workmanship and equipment configuration in order to reduce failure and idling period, increase the specification rate and improve the product quality. 3.Architecture Andon system is a typical distributed control system. It is based on bilayer cable technology.The first layer is industrial Ethernet based on TCP/IP protocol. Andon system can acquire much information from different systems quickly, conveniently and flexibly through this layer. The second layer is profibus industrial control cable based on profibus DP protocol. Profibus is a kind of rapid and secure serial industrial control cable. Through it, Andon system can quickly collect and control various real-time information to ensure its high security. Andon system uses PLC as its main controller to collect and process information and control the system through the connection between profibus, remote field controller, I/O mould and music box, quality desk, quality-pull, QCOS, Data Panel and production line controller and through the HMI communication and data exchange between Ethernet and Andon board, main supervisory computer, PLC and server of other systems. Andon server is the main supervisory computer, used to manage clients, configure system parameter, monitor system status and real-time information, store system information, collect and analyze data and make forms. Office Viewer is the monitoring browse computer. Through it, production supervisors can browse the information on the main supervisory computer. The main monitoring system is based on Client/Server architecture. The main supervisory computer is used as server terminal and other stations are used as client terminals to realize centralized management, distributed control and unified data management. The system can collect real-time data, set up data in the office and monitor production status. The main supervisor computer has realized information publishing so that forms can be read through workshop LAN. It not only ensures data security, but also helps clients¡¯ management and function expansion. The user¡¯s terminal is based on the traditional way. It provides users with operating interface and can response to clients¡¯ requests, visit backstage data resources, result in satisfactory outcome and then return to the terminal. In this way, it has realized centralized business, centralized data and online analysis. On the other hand, based on SQL database and other technology, it has realized unified data record and management to provide information services and decision support for manufacturing supervisors and staff. Based on C/S architecture, the system uses standard TCP/IP Ethernet as platform. It can integrate network language effectively and have better performance. Andon board displays all real-time information about production, equipment and security, including every station call, QCOS alarm, equipment failure, materials transport, buffer status, production line status, actual output, target output, specification rate, idling period and security accident so that manufacturing supervisors and staff can see the production and equipment status clearly. The music box can play 64 kinds of music so that manufacturing supervisors and staff can know the problem and the place immediately when they hear the music. Quality desk is used to call the QC supervisors and manufacturing staff to solve the problem. Data Panel is used to input the information about automobiles. 4.Attributes Andon system is a flexible automation quality control and manufacturing management system. All of the parameter and control in the production line are flexibly configured according to the management of production and quality. It is very complicated and has great information capacity. The system occupies lots of hardware and software resources. Andon system is a universally standard system. It can adapt to the production environment and requirements of various products in the production line.Main supervisory computer is responsible for the information set-up, analysis and processing of overseas Andon system. Consequently, if Ethernet connection is interrupted or the supervisory computer breaks down, the whole system will fail. However, PLC is responsible for the information collection and control of our Andon system while main supervisory computer is in charge of client management, system parameter configuration, system monitoring, database management and analysis and form print. And as a result, if Ethernet connection is interrupted or the supervisory computer breaks down, PLC can still work so that production will not be affected. Although PLC program becomes more and more difficult, however it strengthens the security of the whole system. |
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