Flexible Manufacturing
1 Basic Concept
1 1 Flexibility Flexibility can be expressed in two aspects.
The first aspect is the system's ability to adapt to changes in the external environment, which can be measured by the degree to which the system meets the requirements of new products; the second aspect is the system's ability to adapt to internal changes, which can be measured when there is interference (such as machine failure) ), the system's productivity is measured by the ratio of the expected productivity value without interference. "Flexible" is relative to "rigid". Traditional "rigid" automated production lines mainly achieve mass production of a single variety. The advantage is that the productivity is very high, because the equipment is fixed, the equipment utilization rate is also very high, and the cost of a single product is low. But the price is quite expensive, and it can only process one or a few similar parts, making it difficult to cope with the production of multiple varieties and small and medium batches. As the era of mass production is gradually being replaced by production that adapts to market dynamics, the viability and competitiveness of a manufacturing automation system largely depend on whether it can produce lower-cost products within a short development cycle. , the ability to produce different varieties of products with higher quality. Flexibility has occupied a very important position. Flexibility mainly includes
1) Machine flexibility. When required to produce a series of different types of products, the ease with which the machine can process different parts as the products change.
2) Process flexibility: First, it is the ability to adapt to changes in products or raw materials when the process flow remains unchanged; second, it is the difficulty of changing the corresponding processes in the manufacturing system to adapt to changes in products or raw materials.
3) Product flexibility: First, after a product is updated or completely switched, the system can produce new products very economically and quickly; second, after a product is updated, the ability to inherit and be compatible with useful features of old products ability.
4) Maintenance flexibility: the ability to use multiple methods to query and handle faults to ensure normal production.
5) Production capacity flexibility: The ability of the system to operate economically when production volume changes. This is particularly important for manufacturing systems that organize production according to orders.
6) Expansion flexibility When production needs it, the system structure can be easily expanded, modules added, and the ability to form a larger system.
7) Operational flexibility: The ability to use different machines, materials, and processes to produce a series of products, and the ability to use different processes for the same product.
1 2 Flexible manufacturing technology Flexible manufacturing technology is the sum of various technologies that realize programmed flexible manufacturing and processing of various shapes of processing objects. Flexible manufacturing technology is a technology-intensive technology group. We believe that any processing technology that focuses on flexibility and is suitable for multiple varieties and small and medium-sized batches (including single-piece products) belongs to flexible manufacturing technology. Currently divided according to scale:
1) Flexible Manufacturing System (FMS)
There are many definitions of flexible manufacturing systems. The authoritative definitions are:
The American National Bureau of Standards defines FMS as: "Some equipment connected by a transmission system. The transmission device puts the workpieces on other connecting devices and sends them to various processing equipment, so that the workpieces can be processed accurately, quickly and automatically. The central computer controls the machine tools and Transfer systems and flexible manufacturing systems can sometimes process several different parts at the same time. The International Production Engineering Research Association points out that "a flexible manufacturing system is an automated manufacturing system that can produce any range of product families with minimal human intervention. The flexibility is usually limited by the product families considered when designing the system. ” my country’s national military standards define it as “a flexible manufacturing system is an automated manufacturing system composed of CNC processing equipment, material transportation and storage devices and computer control systems. It includes multiple flexible manufacturing units that can adapt to changes in manufacturing tasks or production environments. Quickly adjust, suitable for multi-variety, small and medium-sized batch production. ” Simply put, FMS is an automated manufacturing system that is composed of a number of CNC equipment, material transportation and storage devices and computer control systems and can be quickly adjusted according to changes in manufacturing tasks and production varieties.
The current common components usually include 4 or more fully automatic CNC machine tools (machining centers and turning centers, etc.), which are connected by a centralized control system and material handling system, which can operate without stopping the machine. Achieve processing and management of multiple varieties and small and medium batches. The current FMS that reflects the overall level of the factory is the first-generation FMS. Japan's "Intelligent Manufacturing System" (IMS) international development project, which has been implemented since 1991, belongs to the second-generation FMS. The truly perfect second-generation FMS is expected to be completed this century. It will not be realized until ten years later.
2) Flexible Manufacturing Cell (FMC)
The advent and use of FMC in production is about 6 to 8 years later than FMS. FMC can be regarded as the smallest FMS. FMS is a product that develops in the direction of cheapness and miniaturization. It is composed of 1 to 2 machining centers, industrial robots, CNC machine tools and material transportation and storage equipment. It is characterized by the realization of single-machine flexibility and automation, and the ability to adapt to processing Flexibility in a wide variety of products. So far it has entered the stage of popularization and application.
3) Flexible manufacturing line (FML)
It is a production line between a single or small-variety large-volume non-flexible automatic line and a small and medium-sized batch multi-variety FMS. The processing equipment can be a general machining center or CNC machine tool; it can also use special machine tools or NC special machine tools. The requirements for the flexibility of the material handling system are lower than those of FMS, but the productivity is higher. It is represented by flexible manufacturing systems in discrete production and decentralized control systems (DCS) in continuous production processes. It is characterized by the realization of production line flexibility and automation. Its technology has become increasingly mature and has entered the practical stage so far.
4) Flexible Manufacturing Factory (FMF)
FMF connects multiple FMS, equipped with an automated three-dimensional warehouse, and uses a computer system to communicate, using a flexible manufacturing process from ordering, design, and processing. , complete FMS from assembly, inspection, transportation to delivery. It includes CAD/CAM and puts the Computer Integrated Manufacturing System (CIMS) into practice, realizing the flexibility and automation of the production system, and thereby realizing the overall factory-wide production management, product processing and material storage and transportation processes. FMF is the highest level of automated production, reflecting the world's most advanced automation application technology. It integrates the automation of manufacturing, product development and operation management into a whole, represented by the intelligent manufacturing system (IMS) that controls the flow of information and material flow. It is characterized by the realization of factory flexibility and automation.
2 Key technologies used in flexible manufacturing
2.1 Computer-aided design
Future CAD technology development will introduce expert systems to make them intelligent and capable Deal with a variety of complex issues. One of the latest breakthroughs in current design technology is photosensitive three-dimensional forming technology. This new technology directly uses CAD data and a computer-controlled laser scanning system to divide the three-dimensional digital model into several layers of two-dimensional sheet graphics and shape them into two-dimensional sheets. The pattern optically scans the photosensitive resin liquid level in the pool, and the scanned liquid level turns into solidified plastic. This cycle of operations scans and shapes layer by layer, and automatically bonds together the layered sheets of solidified plastic. , just by confirming the data, an accurate prototype can be produced within hours. It helps speed up the development of new products and new structures.
2.2 Fuzzy control technology
The practical application of fuzzy mathematics is fuzzy controller. The recently developed high-performance fuzzy controller has a self-learning function, which can continuously obtain new information during the control process and automatically adjust the control amount, greatly improving the system performance, especially the self-learning method based on artificial neural networks. It has attracted great attention from people.
2.3 Artificial intelligence, expert systems and smart sensor technology
So far, the artificial intelligence used in flexible manufacturing technology mostly refers to rule-based expert systems. Expert systems use expert knowledge and reasoning rules to reason and solve various problems (such as explanation, prediction, diagnosis, fault finding, design, planning, monitoring, repair, command and control, etc.).
Because expert systems can easily combine various facts and proven theories with knowledge gained through experience, expert systems enhance flexibility for all aspects of flexible manufacturing. Looking to the future, artificial intelligence (including expert systems) technology, which is characterized by intensive knowledge and uses knowledge processing as a means, will play an increasingly important and critical role in flexible manufacturing (especially intelligent manufacturing). Of the various technologies currently used in flexible manufacturing, artificial intelligence is expected to be the most promising.
It is expected that by the beginning of the 21st century, the application scale of artificial intelligence in flexible manufacturing technology will be four times larger than the current level. Intelligent Manufacturing Technology (IMT) aims to integrate artificial intelligence into all aspects of the manufacturing process and replace or extend some of the mental work of humans in the manufacturing environment by simulating the intelligent activities of experts. During the manufacturing process, the system can automatically monitor its operating status, automatically adjust its parameters when receiving external or internal incentives to achieve the best working condition, and has self-organizing capabilities. Therefore, IMT is called the manufacturing technology of the future 21st century. A rapidly developing field that is of great significance to future intelligent flexible manufacturing technology is smart sensor technology. This technology is produced with computer application technology and artificial intelligence, which enables sensors to have inherent "decision-making" functions.
2 4 Artificial Neural Network Technology
Artificial Neural Network (ANN) is a method that simulates the neural network of intelligent creatures to process information. Therefore, artificial neural network is also an artificial intelligence tool. In the field of automatic control, neural networks will soon be ranked alongside expert systems and fuzzy control systems and become an integral part of modern automation systems.
3 Development Trends of Flexible Manufacturing Technology
3 1 FMC will become a popular technology for development and application
This is because FMC requires much less investment than FMS The economic benefits are similar, and it is more suitable for small and medium-sized enterprises with limited financial resources. At present, many foreign manufacturers have listed FMC as their top priority for development.
3 2 Develop more efficient FML
The demand for FML from multi-variety and large-volume production enterprises such as automobile and tractor factories has attracted great attention from FMS manufacturers. The use of low-cost special CNC machine tools to replace general machining centers will be the development trend of FML.
3 3 Developing in the direction of multi-function
From the simple processing type FMS, we further developed a variety of manufacturing processes such as welding, assembly, inspection and sheet metal processing, as well as casting and forging. Function FMS.
4 Conclusion
Flexible manufacturing technology is a novel conceptual model and new development trend for realizing the factory of the future. It is a strategic measure that determines the future development of manufacturing enterprises. By then, intelligent machinery and people will be integrated with each other to flexibly and comprehensively coordinate all activities of an enterprise's production and operation, from order acceptance to production and sales.
In recent years, flexible manufacturing has been recognized internationally as a scientific "philosophy" of modern industrial production and an advanced model of factory automation. It can be thought of as follows: Flexible manufacturing technology is an important part of automation technology and information technology. On the basis of technology and manufacturing technology, the engineering design, production and management processes that were independent in the past in enterprises are combined with the support of computers and software to form a complete and organic system covering the entire enterprise to achieve global dynamics. Optimization, overall high efficiency, high flexibility, and intelligent manufacturing technology to win the competition. As a cutting-edge technology in the development of manufacturing automation technology in today's world, it provides a grand blueprint for future institutional manufacturing factories and will become the main production model of the institutional manufacturing industry in the 21st century. It realizes the division of virtual networks by ports, MAC addresses, applications, etc., effectively controls the broadcast traffic of the enterprise's internal network and improves the security of the enterprise's internal network.
5 Conclusion
In reality, there are many different types of networks. Some support TCP/IP, and some follow OSI standard protocols. The corresponding layer protocols of each machine are different. Which layer implements the connection requires the use of corresponding network interconnection equipment.
In layman's terms, Layer 2 switching refers to a multi-port switching set line, that is, a network switch.
Its purpose is to replace traditional hubs and improve the effective bandwidth of the network. Mainly used in local area networks. Bridges (hubs) are used between different or same types of LANs. From the protocol layer, they are devices of the data link layer, but they are still methods of network connection, because the LAN IMP itself does not have a network layer, only at the host site. Only on the Internet can there be a network layer or the function of providing network layer services. Unlike bridges, gateways work at the network layer level. This allows for greater flexibility. For example, translating addresses between widely different networks, etc., but this also results in a very slow gateway. Therefore, gateways are generally used for connections between WANs or for interconnection between LANs and WANs. With the evolution of networks and the emergence of 100M high-speed Ethernet, the delay caused by routers in communication between network segments has increasingly become a bottleneck in network information transmission [4]. The emergence of Layer 3 switching technology has solved the bottleneck problem of network information transmission between sub-network segments in large-scale LANs, replaced expensive routers, and has become a practical and economical networking technology.
The composition and technical goals of the flexible center
Through the scientific research and construction of the flexible center, the computer application capabilities and process processing level in the development of large-scale antenna systems will reach the leading level in the country and the international level in the 1990s. It provides a strong guarantee for the completion of key research and development tasks.
(1) Based on flexible manufacturing technology and system integration technology, by configuring advanced CNC processing equipment and computer systems, and using modern design, manufacturing and management technology with computer technology as the core, we will establish an industry-specific flexible manufacturing center.
(2) Apply CAD/CAM technology to realize computer-aided design of key parts of the antenna system, and gradually realize the parallelization of the flexible center design process.
(3) Apply modern information management technology and computer control technology of the processing process to achieve flexibility in the manufacturing process of key parts.
(4) By establishing a network and database cloud environment, create conditions for functional interaction, information integration and resource sharing during the operation of the center.
(5) Improve the unit’s comprehensive strength and modernization level, and improve its ability to adapt to the market.
(6) The overall functional structure of the flexible center is shown in Figure 1, which consists of engineering design system, engineering management system, quality management subsystem, workshop manufacturing subsystem and network database support system.
①The Engineering Management Information Subsystem (EMS) realizes project management, technical status management, inventory management, production plan formulation, and cost management.
②The quality information management subsystem (QMS) realizes the collection, analysis, processing, feedback and quality document management of production process quality information based on Intranet.
③The engineering design subsystem (EDS) application is based on PDM to realize CAD/CAPP/CAM integrated design of key parts of the feed.
④The workshop manufacturing subsystem (WMS) realizes CNC processing of key parts of the antenna, DNC of CNC equipment, production planning and scheduling, etc. The network database support environment (NET/DB) provides an integrated environment for the operation of EMS, EDS, and WMS subsystems, provides intranet services, and supports information integration in the flexible center.