Introduction
Along with economic globalization and information society technology, increasing competition, product competition price competition has been transformed from the traditional competition for the technical content, high-tech products into the mainstream market, innovation is the soul of enterprise development. In order to adapt to new market changes, companies must be listed on the fastest speed, best quality, lowest cost and best service to meet the needs of different users. The face of unpredictable, sustainable development, fast changing market demand, production activities of enterprises must have a high degree of flexibility, changes in market demand rapid response. To this end, exploring new design and manufacturing is the most important means of business survival.
With the rapid development of information technology, there are some advanced design and manufacturing technology, modern design and manufacturing technology development is to continually absorb modern science and technology, digital design and manufacturing technology, functionality, intelligence and networking. Virtual technology has become the most active of manufacturing design technology, its development, the promotion of virtual manufacturing (Vitrual Manufacturing) of the formation and development of mechanical product design, processing, analysis and production organization and management of a virtual simulation environment, so the computer "organization" and "achieve" production, before the actual production of products for manufacturing and other aspects of assessment, to ensure a successful production, thus reducing production costs, reduce time to market, rapid response to market, improve enterprise competitiveness.
1, the content and classification of virtual manufacturing
1.1 The meaning of virtual manufacturing
With the rapid development of manufacturing technology, it also has the connotation of the manufacture of new, more comprehensive understanding. Manufacturing is in accordance with market demand, the use of knowledge and skills, using tools, using effective methods, raw materials to final products and to market the entire process. Virtual Manufacturing (Vitrula Manufacturing VM) refers to the use of computer models and simulation to achieve product design and production technology, information technology, simulation technology, virtual reality technology and high-performance computers, high-speed network to support the computer group Group co-ordination to achieve product design, process planning, manufacturing, performance analysis, quality inspection, and business process management at all levels with the control nature of the product manufacturing process. "Virtual manufacturing" Although it is not the actual manufacturing, but realized the nature of the actual manufacturing process, which in the product design or manufacturing system before the physical realization, we can through the model to simulate and forecast future product form, function, performance and the processability and other possible problems, which can make forward-looking decision-making and optimize the implementation of the program, so that the development of manufacturing technology to the full forecast period. Virtual manufacturing is the actual manufacture of the nature of the computer implementation, it is a variety of computer-aided technology for product life cycle of integrated comprehensive use.
With the actual manufacturing of the material, information, energy conversion function, that is, raw material inputs, production, information, electricity and other energy, to produce the required products and product-related information. Virtual manufacturing is the actual production of "substance" and "energy" of information, the actual production system for the information and information technology to be "material" and "energy" to achieve and the actual production Information on the equivalent exchange of virtual manufacturing while not produce actual products, but it generated information about the product and manufacturing product information needed.
1.2 Classification of virtual manufacturing
Virtual manufacturing and product development involving both the manufacturing-related activities, but also includes business-related organizations and enterprises management. According to the scope of the project activities and the type of virtual manufacturing can be divided into three categories: the design as the core of the Virtual Manufacturing; to produce the core of the Virtual Manufacturing; to control the core of the Virtual Manufacturing.
1). To design the core of virtual manufacturing. To design a virtual manufacturing as the core manufacturing information will introduce the design process, using simulation to optimize product design, so in the design phase can be carried out on parts or whole machine for manufacturing analysis, including process technology analysis, thermodynamic analysis, kinetic and Kinematic analysis. Mainly to solve the "products designed what" question to all aspects of product performance simulation and evaluation;
2). To produce the core of virtual manufacturing. Production will be at the core of virtual manufacturing simulation model of the production process were dissolving in order to evaluate and optimize production processes to low-cost rapid evaluation of different technology options, resource requirements planning, production planning. Mainly to solve "this organization of production is reasonable," the issues in order to simulate the production process, an assessment of each production plan;
3). To control the core of virtual manufacturing. To control the core of the virtual manufacturing simulation technology will be added to the control model and the actual processing, the realization of simulation-based optimal control. Full use of the power of the computer control of the traditional variety of instruments, digital instrumentation functions, optimizing the production line production organization and management activities to be simulated. Mainly to solve the "how to control" issue.
2 the characteristics of virtual manufacturing
Compared with the actual manufacturing, virtual manufacturing with its own characteristics:
1). Virtualization. Virtual manufacturing is not the real manufacturing process, does not produce the actual product, not the real material and energy consumption, through digital means to the real dynamic simulation of the manufacturing process to realize the nature of manufacturing process;
2). Based on digital model of integration. Virtual manufacturing process depends on the model, the model involves a product model, process model, activity model and resource model. These figures on a computer model integration to realize the product design, manufacturing, testing, assembly and other operations, rather than do the traditional prototype repeated changes;
3). To support agile manufacturing. As the entire process of information storage in the computer, the user needs to change or market quickly modified design, rapid investment in production, can substantially reduce the time to develop new products, improve quality and reduce costs;
4). Distribution of co-operation. With computer networks, virtual manufacturing can not sub in different locations, different departments of different professionals to work simultaneously with a product model, mutual exchanges, information sharing, reduce the large number of document generation and delivery time and errors, so that products development of more efficient, high-quality, low cost way to respond to market changes;
5). The simulation results of high confidence. Virtual manufacturing is through the model, efficacy and other simulation techniques to detect design products or work out of the production planning, product development or production makes a successful organization, so it can truly reflect the actual object.
3 key support of virtual manufacturing technology
Virtual manufacturing virtual environment by means of a variety of information access, integration and integrated manufacturing environment that can run, used to improve the assembly of products from concept design to dynamic simulation of all stages. Virtual manufacturing technology involved in many aspects, such as the environment, technical composition, the process of feature extraction, integration, infrastructure, architecture, manufacturing characteristics of data integration, multi-disciplinary cross-functional, decision support tools, interface technology, virtual reality, modeling and simulation and so on. After which three are the core technology of virtual manufacturing.
3.1 Virtual Reality
Virtual Reality (Virtual Reality VR) technology is the United States, Jaron Lanier first proposed in 1989, meaning the technology is the computer directly to the visual, auditory and tactile and other information synthesis, and prompt for the human sense organs, in human generated around a three-dimensional virtual environment. To the people, the real world and virtual space together, integrated with each other for information exchange and feedback. Virtual reality technology, or build a system by its most important feature is the immersion (Immersion), interactive (Interaction) and the concept of (Imagination).
Utilization of virtual reality computer graphics systems, various display and control interface device, the computer generates an interactive 3D virtual environment. Virtual Reality System (VRS) by the human-machine interface, software, technology, virtual computing platforms to achieve components. VRS can be used for dynamic simulation of the real world, through user interaction input and output changes in time according to the virtual environment, people have a feel of immersion feeling.
3.2 Modeling
Virtual manufacturing system is a real manufacturing system in a virtual environment map, is realistic modeling of manufacturing systems, formal and abstract description and said computerized. Virtual manufacturing system modeling, including the production model, product model and process model.
(1) production model. Can be categorized into static and dynamic description of the two aspects described. Is a static description of capacity and production performance of the system description, is given the possibility of product design; dynamic description is the dynamic behavior and state description to predict the whole process of production;
(2) Product model. Product model the manufacturing process, a collection of various entities in the object model. Virtual manufacturing system for product implementation process to make the integration of all activities, they must have complete the product Mo Xing, the product model Miaoshu the Xin Xi Ji Bao Han product structure, product Xingzhuang characteristics of static information, Huan contains inspection can Jinxingganshe , the performance analysis of dynamic information and so on, is the ability to map, the implementation of the abstract and other products extracted all the information required for each activity models;
(3) process model. Will affect the manufacturing process parameters and functions to link the product design attributes to reflect the production model of the interaction between models and products. Process model must have the following features: computer simulation technology, manufacturing data sheets, manufacturing planning, statistical model and the physical and mathematical models.
3.3 Simulation
Is the application of computer simulation of complex systems through abstraction and simplification of reality form a system model, based on the analysis and then run this model in order to obtain a series of statistical properties of the system. As the simulation model based on targeting methods, by means of the computer's speed computing power that can simulate the actual production of a very short period of time in the production cycle takes a long time so you can shorten the decision-making time, to avoid the financial, human and time waste, and can repeat the simulation, optimization implementation.
Simulation of the basic steps are: study system, data collection for creating a system model simulation algorithm * * to determine the establishment of God running simulation model simulation model * output results and analysis. Virtual manufacturing system for product development related to product modeling and simulation, design process planning simulation, simulation of the actual behavior of the production process, assembly process simulation, process simulation testing to evaluate the results of the design, the design process to achieve the early feedback, reduce or avoid design error.
4 Virtual Manufacturing Technology Analysis
Despite the virtual manufacturing technology in recent years in the international community has developed rapidly, but currently lacks the whole process from product design to carry out highly virtual manufacturing research, embodied in the following.
4.1 based on integrated digital product model technology is still in the concept phase
(1) CAD model of product information content is too low. CAD model of the product design process is formed, a lot of information (geometry of the non-geometric) need to record in which it is an important data source. In virtual manufacturing, many analysis models need to extract from the CAD model of the appropriate information. However, the current CAD model geometry entities mainly from the perspective of describing the product is far from a comprehensive description of products, can provide too little sharing of information;
(2) the existing CAD model can not support the concept of product design. New product design to go through conceptual design, detailed design, product and manufacturing process planning several processes, and CAD models only support the detailed design of products;
(3) the lack of good product information reuse mechanism. Since the current between the various application software products for data exchange is mainly through a dedicated data interface to achieve this conversion is a simple mapping of data the same problem, can not achieve the automatic conversion of data between model and derived no doubt increased the virtual manufacturing product development complexity.
4.2 Product Innovation Support Tools is not yet fully
(1) lack of creative design support system. Product Innovation is a comprehensive science, new technologies, new materials, new technology support. Virtual manufacturing environment for the innovative design provides a good operational mechanism, but further development of innovative organizational design support systems;
(2) the lack of knowledge combined with the virtual manufacturing tools. Knowledge can create innovative products and new technology, product innovation-oriented knowledge. However, due to the complexity of knowledge representation and organization and importance, how virtual manufacturing with integrated digital product is a problem to be solved;
(3) the lack of interactive shape design and the integration of virtual manufacturing tools.
Currently, virtual manufacturing is considered the most promising product innovations. How to solve the overall positioning of the product, design, interactive introduction to the product shape design and virtual manufacturing with organically integrate further studies are needed.
4.3 digital technology products
(1) based on product data management (PDM) integration with other software issues. Digital product is the core of PDM technology, currently, there has been various versions of PDM software, but the lack of standards, the resulting software and other applications of the PDM system integration issues. In the virtual environment, the professional, the department staff to work on the same product model, must be resolved PDM integration with other applications;
(2) virtual product development, product data organization system. Way of virtual product development products generated DMU product structure tree only to reflect the product design phase structural hierarchy, the product assembly sequence but also reflect the production process, the manufacturing sector directly under the product number of prototype manufacturing. Therefore, the study product for virtual product development system of data organization is truly necessary;
(3) and the digital product model data organization and management.
Products, digital products, including the establishment of numerical models and its related performance indicators, including structural analysis, kinematics analysis, dynamic analysis, thermal analysis results, the products provide the theoretical basis of stereotypes, and to transform performance. How to effectively address the data organization and management, so effectively for the needs of virtual manufacturing is the research focus.
4.4 Manufacturing process simulation modeling methods and techniques
Physics-based simulation model of the manufacturing process have been widely used, but the modeling methods and modeling techniques yet breakthrough.
(1) virtual machining tools to be improved. At present, many commercial software can be "machinability" rating, but a large number of virtual manufacturing research and development needed analysis of the virtual machining tools, such as analysis functions with the processing of cutting force simulation system, etc.;
(2) the basic theory of virtual assembly. Virtual manufacturing virtual with the tolerance analysis and synthesis technology is also a lack of theoretical basis, in the model generation and the ISO standard tolerances, geometrical tolerances of support, there are many problems, the urgent need to address;
(Three) assembly process planning for further study. The current virtual assembly process planning based on research have significant limitations mainly refer to: consider only the direction of translation along the coordinate Zhou, Zhuang Pei Yundongfangshi too Jian Dan; emphasis on geometry, Gong Cheng semantic knowledge of Li Yong to be 加强; assembly sequence Selection criteria are not extensive enough and uniform;
(4) virtual testing technology. Successful application of virtual test is a "virtual product development," the key to technology is essential. When all aspects of computerization, the testing and efficacy aspects affecting the efficiency became important factors.
5 Conclusion
From the actual manufacture of the "virtual manufacturing" into the international manufacturing industry in the promotion of information technology the most significant changes occurred. Virtual manufacturing in industrialized countries like the United States, Germany, Japan, etc., have been varying degrees of extensive research and application. In China, Tsinghua University, Beijing University of Aeronautics Air disgust, Harbin Institute of Technology teaching units and other research has also carried out research work in this area. Current research focuses on virtual manufacturing applications is based on the direction of three-dimensional virtual product design, process simulation and product assembly simulation to study how to generate products with high reliability of the virtual prototype, product design stage to achieve a higher degree of confidence to predict The design of the final product performance and manufacturability. With deep research and related technologies continue to develop virtual manufacturing will be more widely used.