Discussion on digital product definition technolog

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Discussion on digital product definition technology of aviation missile

Abstract: the premise of realizing information sharing under virtual manufacturing production mode is the application of digital product definition technology. This paper expounds the digital product definition technology and its key components in detail, preliminarily discusses the digital product definition technology of aviation missile, and puts forward suggestions on the application of digital product definition technology of aviation missile at the present stage

key words: virtual manufacturing; PDM; Digital product definition

1 overview

1.1 question raised

at present, the rapid development of computer technology has greatly affected our production and lifestyle. In order to quickly respond to market demand and shorten product development cycle, the production mode of products has gradually entered the stage of virtual manufacturing production mode, which is mainly based on virtual simulation verification and supplemented by physical prototype verification. This is a production mode based on agile manufacturing, virtual manufacturing, network manufacturing and global manufacturing. It requires that the problems in the whole life cycle should be considered from the beginning of product design. The characteristics of virtual manufacturing production mode are that it emphasizes the parallel and orderly product development based on collaboration and the joint decision-making process of upstream and downstream, and carries out process control and management under product data management (PDM), solves the contradiction between design and other links of products, and provides an effective way for the automation of multi product single piece small batch production. In the virtual manufacturing production mode, product design, manufacturing and other links are based on collaboration. Product information feedback runs through all stages of the life cycle. In order to reduce the probability of error in information feedback, it is required that the description of products in all stages should be consistent as far as possible. However, in each stage and link of the actual production process, due to the different levels of actual needs and understanding of products, the description of product information is different. When we share product information resources, we have to spend a lot of time sorting out these information, which affects the efficiency of product collaborative development and design. Therefore, how to summarize a set of product information specifications suitable for the enterprise in practice and adopt the working method of unified model design is particularly important

1.2 solution

the concept of digital product definition is based on the above problems. Digital product definition (DPD) is a digital description of the product in the whole life cycle of the product, including the description of the digital information in each stage of the product life cycle and the description of the relationship between the digital information in each stage, so as to carry out the remote design and manufacturing of the product. Digital product definition is an important enabling technology of virtual manufacturing production mode. Through the definition of digital products, the form of product models in each professional stage will be standardized, providing an environmental basis for collaborative design and communication of personnel in different majors and stages

1.3 development of digital product definition technology at home and abroad

digital product definition technology has been studied and applied abroad for a long time. For example, Boeing successfully used paperless design technology in the design of Boeing 777 aircraft, realized the three-dimensional digital definition and digital pre assembly of the whole aircraft shape, structural parts and the whole aircraft system, launched the international first full aircraft electronic prototype, and realized the first full aircraft digital coordination, full aircraft digital manufacturing and full aircraft digital pre assembly. In the process of realizing "paperless design", Boeing redefined the product configuration in general, separated the configuration definition work from the design department and assigned it to the manufacturing engineering department, so that the product configuration and process definition, tooling design, NC programming, and process documentation work form a large definition stage, and the digital product definition technology is directly applied to the process of aircraft design, manufacturing, and management, Basically realize the reengineering of production process. In contrast, the domestic research in the field of digital product definition started late. With the implementation of CIMS Engineering in some domestic enterprises, the research on relevant technology is becoming a new hot spot

2 key components of digital product definition technology

the key components of digital product definition technology are composed of digital product model, product data management (PDM) and related supporting technologies. These supporting technologies include digital tool definition technology, information integration technology, etc. We will introduce each component technology separately below

2.1 digital product model

2.1.1 connotation of digital product model

digital product model is the key enabling technology of digital product definition technology, and its concept originates from the digital description of products. Digital product model should support the subsequent product design and manufacturing process. Therefore, its meaning includes: geometric model and non geometric information model centered on geometric and topological information

geometric model is the public basic part of digital product model, and its development and evolution has gone through a long process. In the era of two-dimensional drawing design, the tool for designers and manufacturers to communicate is two-dimensional geometric drawings. People outline the geometric shape of products and complete the exchange of design ideas and manufacturing methods through drawings and the standard drawing method and interpretation provisions of drawings; In the era of 3D aided design, 3D model has gradually become an important auxiliary means of design, and the geometric description of products has changed from the original, but in the laboratory? Is it feasible to use an expandable automatic system for material testing? This means that two-dimensional wireframe has developed to three-dimensional wireframe, three-dimensional solid model and today's feature model, and the geometry that can be described has changed from a simple plane model to today's sculpture surface model. The geometric model of the product not only contains its geometric attributes, but also contains attribute information for process design and processing and manufacturing, such as the datum plane and datum point of the design process, so as to ensure that it can be applied to subsequent processing and manufacturing. The non geometric information model of the product is a digital description of the characteristic attributes of the product in the life cycle activities, such as the requirements, functions, materials, manufacturing tolerances, assembly relations, maintenance and other product characteristic attributes and management attributes of the digital description. Product structure is the embodiment of the characteristic attribute relationship of all aspects of products

a unified and complete product data model is the basis for realizing the integration of digital product development process. Under the virtual manufacturing production mode, product data often needs to be exchanged between different application systems, and the requirements for information sharing are becoming higher and higher. It is urgent to realize the standardization of product information description. In modern CAD software system, the concept based on master model is proposed. There are many understandings about the definition of the main model. The explanation of Ge engine department for the main model is quoted here. Ge engine department defines the main model as a single geometric representation (3D representation is the most ideal); This geometric representation is established in the conceptual design stage and used in the whole manufacturing process by using feature parameter modeling technology in the associated environment. At the same time, in the process of product design, manufacturing and after-sales service, the relevant components of the main model are closely integrated, and various updates can be transferred into each individual design behavior of the main model, which provides conditions for real parallel analysis and parallel manufacturing

2.1.2 establishment method of digital product model

the establishment of digital product model should fully consider the needs of model generation in each stage, and ensure the consistency, integrity and reusability of model data in each stage. Therefore, a core model of the product should be established. The core model uses a highly abstract method to describe product information and support the product design process. Various applications can easily extract or deduce the information they need from the core model from different perspectives. Because the design of products must meet certain functions, from the perspective of function, the digital product model has a good hierarchy, and the function description also has a strong abstraction. The structural hierarchy of the digital product model is shown in the figure below

figure structure hierarchy diagram of digital product model

the whole model is composed of core model, analysis model and other application models. The core model is established interactively in the process of product design, which is mainly composed of functional model and entity model. Function model describes information through product function units, which is based on entity model. Each analysis model and other application models can be derived from the core model

the establishment of product solid model can be realized through the functions of existing CAD 3D software. The establishment of product function model is a very complex work. It has the following key technologies to be solved. First, classification technology. There are many kinds of products and complex structures. Different categories should be divided according to different levels. For enterprises with different products, they can be classified according to different product types; Group technology can be used for reference in product classification. Second, model construction technology. The construction process of product model is actually the product design process, which should conform to the product design specification, and can dynamically modify the model in the design. Third, the derivative technology of application model, analysis model and product core model. The core model is a highly abstract model. The analysis model and other application models include the models of various disciplines related to product design. The core model cannot be directly used as an analysis model. Therefore, it is necessary to develop corresponding transformation tools for each analysis model and application model

2.2 product data management (PDM)

Product data management (PDM) is the basis for the realization of digital product definition technology. PDM manages all product related information and processes. It integrates the data management ability of the database, the communication ability of the network and the control ability of the process, and realizes the unified management of product data in the distributed environment. PDM realizes the management of documents and drawings, and realizes the static product support data (such as industrial standards, product specifications, standard parts and general parts data) Management of product design data (such as product definition model, product drawing, BOM, documents with steady growth in design export, process documents, NC code, CAE analysis report, etc.) and dynamic product process data (data reflecting the distribution, change, approval and signing of design data). In the implementation of the whole digital product definition technology, it is necessary to realize the digital configuration control of remote and distributed products, the approval, issuance and change process control of digital product definition through PDM, and provide multi professional comprehensive optimization and shared data and computer application environment

2.3 definition of digital tools

definition of digital tools is to add semantic definitions to product data. As one of the supporting technologies of digital product definition technology, digital tool definition is mainly reflected in the construction process of digital product model. The important feature that distinguishes digital product model from traditional model is that digital product model provides semantic interpretation function. Semantics can make the computer clearly know the engineering meaning of each part of the established product, so that it can analyze and deduce the product model. Among the existing tools, predicate logic has strong descriptive and deductive reasoning functions, and can be used as a tool for semantic definition

2.4 information integration

information integration technology is the bottom technology of digital product definition technology. Establish life cycle

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