Preliminary study on the development trend of digi

2022-08-22
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The research and application of CAPP technology has experienced the stages of intelligent technology research, single professional engineering application and platform chemical engineering application in China. In recent years, the tool system based on CAPP has been widely used in various industries in China, and has achieved good application results

at present, the application of informatization in aviation manufacturing industry has been fully valued and developed by enterprises. The structure of aircraft products is complex, and the structure, materials and states of parts are diverse. The types of processes cover parts machining, sheet metal, metallurgical process, composite material processing, component assembly, final assembly and testing, and the process is complex. Information technology is widely used in business fields such as product design, process design, tooling design, manufacturing process and testing. Especially in the manufacturing field in recent years, with the comprehensive application of PDM, CAPP and MES, the functions of process document preparation, process information management and pdm/capp/mes integration are realized, the informatization and integration of process business are realized, and the production preparation, manufacturing process Informatization in quality control and other fields has shortened the product development and production cycle, improved product quality, achieved obvious economic benefits, and greatly improved the core competitiveness of enterprises

but in general, the application of digital technology of aviation technology in China is still at a low level of "Computerization", and a lot of work is needed to meet the urgent needs of the development and production of new aircraft

application requirements of aircraft process information technology

aircraft products are basically developed and produced in a single piece and small batch production mode. From trial production, finalization, small batch production to batch production, the process is constantly optimized, refined and improved. In particular, the continuous application of new materials, new structures, new processes, new equipment and new technologies forces the aircraft manufacturing technology to be constantly innovated, optimized and improved in order to meet the requirements of the development and mass production of new aircraft (such as large aircraft, new fighters, etc.)

in terms of process design methods, the current aircraft manufacturing CAPP basically adopts interactive and typical process retrieval and revision, which is limited to the formation of process instruction documents. It is "experience based design". Relying on the process knowledge and experience of the process personnel and the typical process stored in the system, it is difficult to optimize and improve the process, and the quality of process preparation is also limited. As mentioned above, aircraft is a product with a very high degree of innovation and integration, and the processes such as aircraft structural parts, large sheet metal parts, assembly and electrical assembly are very complex, with high technical requirements and NC machining requirements. A lot of information and knowledge need to be gathered for decision-making in process design, especially the large application of composite components in new aircraft, Some key technologies in the field of composite technology often need to be solved and experience accumulated. Therefore, "experience based design" cannot meet the needs of process innovation and optimization

in the current aircraft manufacturing process, the transmission methods of digital quantity and analog quantity coexist, and the process links still largely use two-dimensional engineering drawings and process cards. The aircraft product design process has fully adopted the three-dimensional digital prototype mode. In order to realize the parallel of process and design, process and tooling, process and manufacturing and testing, it is necessary to realize the digital quantity transmission based on three-dimensional model in the process business. Aircraft manufacturing enterprises have the needs of full three-dimensional digital prototype, development and production, finalization and batch production of existing models in combination with large aircraft, new fighters and other projects, and there is an urgent need for process design and management based on three-dimensional product models

aircraft process technology preparation is generally divided into product manufacturability analysis, determination of general process scheme (division of labor scheme, assembly coordination scheme, part manufacturing scheme and tooling scheme, etc.), pbom construction (determination and decomposition of assembly unit, process division route) Workshop process technology preparation (process specification/ao/fo preparation, NC programming, process simulation, process equipment requirements, etc.) and process field application and other interrelated business processes. Aircraft production and product configuration are carried out according to product batches and sorties, and strict requirements are placed on engineering technology status management, process configuration management and production quality archives management. In terms of process management, CAPP currently realizes information management and approval process management, but it is obviously insufficient in process business process management, technical state management and process configuration management, which makes it difficult to ensure the integrity, accuracy and consistency of product process information

in addition, at present, the process instructions are circulated in the production workshop in the form of paper documents, and the implementation of the process instructions is realized through human management. In this way, it is difficult to avoid such phenomena as NC tool error, NC program error, wrong equipment state and missing and wrong installation of parts and components during assembly. Process design is divorced from process execution, and production quality control is often handled after the event rather than prevention in advance

therefore, the current application of CAPP system in aviation manufacturing enterprises stays at the level of process document preparation tools, and plays a great role in popularizing the application of process informatization, but it is seriously insufficient in improving the quality of process design, optimizing the process, and improving the process technology of enterprises. In order to adapt to the characteristics of aircraft manufacturing technology and meet the needs of new aircraft development and production, the aircraft manufacturing process information integration system should give full play to the core role of process data and develop in the direction of application depth, intelligence and integration depth

development trend of aircraft digital technology

in order to meet the needs of aircraft development and production, aircraft manufacturing enterprises are further promoting the development and industrialized application of aircraft digital technology. The development of aircraft digital process technology should focus on the following four aspects:

(1) visual innovative process design based on three-dimensional model

(2) application of knowledge-based system and professional process design

(3) pbom based process organization and management

(4) visual process execution system

1 visual innovative process design based on three-dimensional model

it has become a common understanding of all aviation enterprises to make full use of the three-dimensional model of products in the process, production preparation and manufacturing links to realize the transmission and connection of digital quantities such as products, processes, tooling, manufacturing and testing and debugging

the rationality and correctness of assembly process design directly affect product quality, production organization efficiency, aviation product cost and manufacturing cycle. The assembly process design based on two-dimensional graphics is very easy to omit key links and is not easy to recheck and correct. It is far from meeting the requirements of new product development and production, and it is incompatible with product design. The three-dimensional process design of product assembly directly applies the three-dimensional digital simulation of product design and process equipment design, reasonably plans the assembly process and carries out assembly simulation, finds out the design errors and uncoordinated problems to the greatest extent, is conducive to the early exposure and solution of design problems, and can greatly shorten the development cycle and development cost

the structure of aircraft parts is complex, and the processing process of parts is combined by text description and two-dimensional process diagram. It is difficult to clearly describe the processing process of complex aircraft structural parts and sheet metal parts by using two-dimensional diagrams, which often leads to misunderstandings and omissions, which is not convenient for the process preparation of technicians and the understanding and implementation of operators

the process design based on three-dimensional model will inevitably bring significant changes to the process application mode. In the process design system based on three-dimensional model, the expression forms of process are structured process and three-dimensional process model, rather than the existing paper-based productive process documents. Technologists browse and query 3D product models through computers, and use 3D production tools to make visual process

the practical and feasible system implementation scheme to realize efficient and reasonable process design by using three-dimensional models is:

(1) the assembly process adopts the product model lightweight tool for lightweight processing, and then uses the assembly process manufacturing tool to make the assembly process according to the assembly planning and assembly route, finally forms the assembly process model, and establishes the interconnection with the structured assembly process information. For example, for the design of aircraft component assembly Ao, Chengdu Airlines integrated 3dvia composer in the structured process design system as an assembly process production tool, realizing the close combination of Ao structured process and lightweight assembly process model based on three-dimensional model, and realizing visual assembly process design and on-site visual assembly

(2) for the part process, make full use of the NC machining simulation system, sheet metal machining simulation system, casting process simulation system or cad/cam system to realize its integration, transfer the process technical parameter information, introduce the three-dimensional model of machine tool equipment and process equipment, and use the process simulation process and simulation results as the part processing process model. The process simulation system can find problems as soon as possible, better optimize the process, and change the process design management from experience based process design management to digital simulation verification based process design management, which can change the current situation that the process design work mainly depends on experience inheritance and actual experiments, but the independent innovation ability is very weak. For example, casting technicians can simulate the pouring process on the computer according to the three-dimensional model of the product, automatically generate the position and number of gates and risers, and even complete the design of the whole pouring mold

2 application of knowledge-based system and professional process design

process design is the collection of product information, enterprise manufacturing resources and capacity information, process professional technology and experience knowledge, schedule and cost requirements and other information. In the process of process design, it is necessary to integrate various factors for decision-making and planning

knowledge processing and management technology is a feasible way to realize process decision-making. By summarizing the manufacturing resource information, material information, process technology and experience knowledge used in the process of manufacturing process design management, the structural engineering knowledge model and knowledge base are established to realize the engineering knowledge management system, and provide the functions of knowledge search, knowledge retrieval and query, knowledge-based decision support, and provide information, knowledge, analysis and decision-making basis for the process decision-making process through the network environment

as mentioned above, the current CAPP application is mainly to realize the preparation of various professional process procedures and instruction documents on the basis of a general interactive design tool, lacking consideration of the inherent characteristics of each process specialty. Therefore, with the further deepening of application, it is inevitable that in addition to technical difficulties, it is required to fully analyze the process design characteristics and characteristic requirements of each specialty, and develop and realize the process design and management functions of each specialty with the support of knowledge-based system. For example, in the CNC center of Chengdu Aircraft Corporation, there are many complex slots and ribs for the complex structure of aircraft structural parts such as frames, beams and wallboards, which have high requirements for NC machining. After the development and application of feature-based intelligent process decision-making, automatic NC programming and numerical control machining simulation functions, the maintenance life of instruments is greatly improved, and the efficiency and quality of process design and NC programming will be longer

due to the extensive use of composite structural parts in new aircraft, the processing technology of composite structural parts needs to be improved and accumulated. Applied knowledge-based system and professional process design tools for composites none

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