1、PDF外文：http:/ of Flexible Manufacturing System using Virtual Manufacturing Paradigm Sung-Chung Kim* and Kyung-Hyun Choi School of mechanical engineering, Chungbuk National University, Cheongju, South Korea, School of mechanical engineering, Cheju National University, Cheju, South Korea ABSTRACT The i
2、mportance of Virtual Manufacturing System is increasing in the area of developing new manufacturing processes, implementing automated workcells, designing plant facility layouts and workplace ergonomics. Virtual manufacturing system is a computer system that can generate the same information about m
3、anufacturing system structure, states, and behaviors as is observed in a real manufacturing. In this research, a virtual manufacturing system for flexible manufacturing cells (VFMC), (which is a useful tool for building Computer Integrated Manufacturing (CIM),) has been developed using object-orient
4、ed paradigm, and implemented with software QUEST/IGRIP. Three object models used in the system are the product model, the facility model, and the process model. The concrete behaviors of a flexible manufacturing cell are represented by the task-oriented description diagram, TID. An example simulatio
5、n is executed to evaluate applicability of the developed models, and to prove the potential value of virtual manufacturing paradigm. Key Words : FMS, virtual manufacturing system, CIM, object-oriented paradigm, TID 1 Recent trends in manufacturi
6、ng systems, such as the need for customized products by small batches and for fast product renewal rates, have been demanding new paradigms in manufacturing. Therefore, the modern manufacturing systems are needed to be adaptable, and have the capability to reconfigure or self configure t
7、heir own structure. Flexible Manufacturing Cells (FMCs) are generally recognized as the best productivity tool for small to medium batch manufacturing, and are also basic unit to construct a shop floor which is an important leve for developing computer integrated manufacturing (CIM). However,
8、due to its complexity, the modeling and operation methodology related to FMC should be verified before implementation. As one of approaches to these requirements, Virtual Manufacturing (VM) approach has been introduced, and known as a effective paradigm for generating a model of manufact
9、uring systems and simulating manufacturing processes instead of their operations in the real world. VM pursues the informational equivalence with real manufacturing systems. Therefore, the concept of Virtual Manufacturing System is expected to provide dramatic benefits in reducing cycle times, manuf
10、acturing and production costs, and improving communications across global facilities to launch new products faster, improve productivity and reduce operations costs for existing product shop 1,2. With an object-oriented paradigm, computer-based technologies s
11、uch as virtual prototyping and virtual factory are employed as a basic concept for developing the manufacturing processes, including the layout of the optimal facility, to produce products. Virtual prototyping is a process by which advanced computer simulation enables early evaluation of new product
12、s or machines concept without actually fabricating physical machines or products. Bodner, et al.,3 concentrated on the decision problems associated with individual machines that assemble electronic components onto printed circuit boards (PCBs). Virtual factory is a realistic, highly visual, 3D graph
13、ical representation of an actual factory floor with the real world complexity linked to the production controlling system and the real factory. Virtual factories are increasingly used within manufacturing industries as representations of physical plants, for example, VirtualWork system for represent
14、ation of shop floor factory4. Despite its benefits and applicability, VM systems should deal with a number of models of various types and require a large amount of computation for simulating behavior of equipment on a shop floor. To cope with this complexity in manufacturing, it is necessary t
15、o introduce open system architecture of modeling and simulation for VM systems. In this paper, three models, which are product, device, and process models will be addressed. Especially process model for FMC will be emphasizedusing QUEST/IGRIP as an implementation issue. The open system a
16、rchitecture consists of well-formalized modules for modeling and simulation that have carefully decomposed functions and well-defined interface with 2 other modules. 2. Concept of virtual manufacturing Virtual Manufacturing System is a computer model that represents the precise an
17、d whole structure of manufacturing systems and simulates their physical and logical behavior in operation, as well as interacting with the real manufacturing system. Its concept is specified as the model of present or future manufacturing systems with all products, processes, and control data. Befor
18、e information and control data are used in the real system, their verification is performed within virtual manufacturing environment. In addition, its status and information is fed back to the virtual system from the real system. Virtual environments will provide visualization technology for v
19、irtual manufacturing. The virtual prototype is an essential component in the virtual product life cycle, while the virtual factory caters for operations needed for fabricating products. Therefore, the developments in the area of virtual prototyping and virtual factory will enhance the capabilities o
20、f virtual manufacturing. The major benefit of a virtual manufacturing is that physical system components (such as equipment and materials) as well as conceptual system compvonents (e.g., process plans and equipment schedules) can be easily represented through the creation of virtual manufactur
21、ing entities that emulate their structure and function. These entities can be added to or removed from the virtual plant as necessary with minimal impact on other system data. The software entities of the virtual factory have a high correspondence with real system components, thereby lending validit
22、y to simulations carried out in the virtual system meant to aid decision-makers in the real system. For virtual manufacturing, three major paradigms have been proposed, such as Design- centered VM, Production-centered VM, and Control- centered VM. The design-centered VM provides an environment
23、 for designers to design products and to evaluate the manufacturability and affordability of products. The results of design-centered VM include the product model, cost estimate, and so forth. Thus, potential problems with the design can be identified and its merit can be estimated. In order to main
24、tain the manufacturing proficiency without actual building products, production-centered VM provides an environment for generating process plans and production plans, for planning resource requirements (new equipment purchase, etc.), and for evaluating these plans. This can provide more accurate cos
25、t information and schedules for product delivery. By providing the capability to simulate actual production, control-centered VM offers the environment for engineers to evaluate new or revised product designs with respect to shop floor related activities. Control-centered VM provides information for optimizing
