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The application and development trend of modern CAPP

I. Introduction

in the late 1960s, people began the research and development of CAPP. Norway and the former Soviet Union were the first countries to study CAPP technology. However, a landmark in the history of CAPP development is the CAPP (CAM-I's automated process planning) system developed by CAM-I, an international organization based in the United States, in 1976. The earliest CAPP systems developed in China are the revised tojicap system of Tongji University and the generative CAOS system of Northwestern Polytechnic University, both of which were completed in the early 1980s

after more than 20 years, a lot of discussion and Research on CAPP technology have been carried out at home and abroad, and progress has been made in both depth and breadth of research

however, compared with CAD, cam and other computer-aided technologies, CAPP is still a weak link in application. On the one hand, this is determined by the complexity and characteristics of process design problems; On the other hand, it is also influenced by the background and guiding ideology of CAPP development. Therefore, although various new concepts and methods are emerging in CAPP research at home and abroad, it is a recognized fact that the development of CAPP lacks a solid practical foundation

from the perspective of CAPP application, this paper reviews the development history of CAPP and discusses the future development of CAPP, in order to provide some ideas for the application of CAPP in manufacturing informatization

second, revised/generative CAPP system based on automation idea

in the traditional CAPP research and development, people divide CAPP system into two categories according to the process decision-making method: Revised (variant, also known as derivative) CAPP system and generative (also known as generative) CAPP system. According to the technical development and actual development needs, there are also hybrid systems compatible with the above two methods, as well as CAPP expert systems that have a greater impact on the application of artificial intelligence (AI) and expert system (ES) technology. This kind of system takes automation as the sole goal, in order to replace the process personnel in the process design. Therefore, many problems in the development and application are caused: the system development cycle is long, the cost is high, and the difficulty is great; Technicians need to input a large amount of part information interactively in use, which is troublesome and error prone, and it is difficult to master the use of the system; The system has limited functions and application scope (large limitations), and lacks flexibility and applicability to adapt to changes in the production environment, making it difficult to popularize and apply

in order to solve the above problems, the development of development tools (including expert system development tools), the application of object-oriented (O-O) technology and the integrated application of cad/capp have been explored at home and abroad, but the practicality of CAPP has not been effectively promoted

Third, practical CAPP system based on Computerization thought

since the 1990s, the practical problem of CAPP has attracted the attention of researchers and enterprise technicians. The practical CAPP system, which aims to realize the computerization of process design or emphasizes the auxiliary role of computer in CAPP application, has become a new theme. These practical CAPP systems are either special development or application development based on commercialized systems, which can be roughly divided into the following two categories

1. Process card filling system based on word/excel/autocad and other graphic systems

due to the problems in the application of revised/generative CAPP with automation as the goal, many enterprises develop process card filling system based on general software such as word/excel/autocad. In these systems, many computer cards based on simple templates have only achieved certain application effects, but many enterprises have spent a lot of manpower and material resources on the basis of process standardization, and achieved good application effects

since 1997, China has launched several commercialized CAPP systems, many of which are process card filling tool systems based on AutoCAD and other graphic systems. Such systems unilaterally emphasize the "what you see is what you get" of process design, completely take documents as the core, and ignore the importance of product process data in enterprise informatization. There are fatal problems that it is difficult to ensure the accuracy and consistency of product process data and the integration of process information. This kind of system is managed in the form of files. Although some claim database management, in fact, it is based on the concept of file encapsulation. The accuracy and consistency of product process data and the integration of process information cannot be solved

2. CAPP system based on structured data

from the perspective of information system development, it is analyzed that the cold brittleness transition temperature TK and fat50 measured by a series of impact experiments involved in the product process documents are conditional, which can only be used as the data/information for the evaluation of material brittleness bias, establish a structured data model, and carry out process design driven by the model. The special CAPP system developed by some enterprises basically belongs to this kind of system, and most of them use the general database management system for development. CAPPFramework, as a commercial CAPP application framework, based on object-oriented analysis and information modeling, adopts ODBC technology to adapt to various relational database systems, and realizes the "WYSIWYG" process design driven by the model. It has the protection and installation interface of overcurrent, overvoltage, overload, etc., which lays a good foundation for the reliable and effective integration of process information and the in-depth application of CAPP

in the commercialized CAPP system launched in China, although some also emphasize the importance of product process data, they still organize data with documents as the core, so the degree of data structure is low. This kind of system can only be called CAPP system based on semi-structured data

the development trend of practical CAPP system seems to fall back to the primary stage of CAPP system development, but in fact, it is not so. At present, in the development and application process of practical CAPP system, its purpose is very different from the traditional goal. This kind of CAPP system has been applied in more and more domestic enterprises, and has achieved quite remarkable results in just a few years. At present, the development of CAPP is gradually embodying modern advanced manufacturing ideas and developing towards the manufacturing process information system integrating process design and process management

IV. product oriented CAPP application and manufacturing process information system

in manufacturing enterprises, the process design of the final product in the whole life cycle usually involves various process designs such as product assembly process, machining process, sheet metal stamping process, welding process, heat treatment process, blank manufacturing process, repair process, etc. in the machining process of general products, it usually involves rotating parts Various types of parts such as box parts, support parts, etc. Obviously, if the CAPP application mode with parts and components as the main object is adopted, the application of CAPP in enterprises can only be partial, and the application of CAPP is lack of due breadth, which makes the development of CAPP lack a solid practical foundation. From the long-term perspective of enterprise development, it will inevitably lead to inconsistency and disharmony in enterprise process management, which will fundamentally hinder the application and development of CAPP. The application of CAPP should move from the local application with components as the main object to the comprehensive application with the whole product as the object, realize the integration of product process design and management, and establish an enterprise manufacturing process information system

1. product oriented CAPP methodology

the basic content of product oriented CAPP methodology is: CAPP system should first be an interactive computer application system centered on product process data, which integrates process design and information management, and gradually integrates multi process decision-making hybrid technology such as retrieval, revision, creation and multi artificial intelligence technology, so as to realize human machine hybrid intelligence and human The integration of technology and management will gradually and partially realize the automation of process design and management, improve the work efficiency of process personnel from the aspects of design and management, and continuously accumulate the experience of process designers in the application

(1) CAPP system should first be an interactive computer application system. Under the loading mode of mechanical transmission system driven by electromechanical speed regulation system, the process personnel are the main body of process decision-making. The system adopts multi process decision-making hybrid technology such as retrieval, revision, creation and multi artificial intelligence technology, which will focus on the automation of local process decision-making function, As one of the means to improve the working efficiency of process personnel as a whole, rather than simply realizing the automation of the whole process of process decision-making, it should not become the only or main goal of CAPP

(2) product process data is the center of CAPP system. Product process data is an important part of product data and also the collection place of enterprise production information. The integrity and consistency of product process data and the integration and sharing of enterprise product process information are of great significance for enterprise informatization. Process card is the formatted form of process data, which can be automatically generated by the system. On this basis, CAPP can also automatically complete various statistical summary functions at all levels (product level, component level, part level), such as tooling equipment, materials, process key parts, outsourced parts, process allocation man hour quota, auxiliary materials, key processes, and automatically generate summary statistical reports (details), which can not only greatly improve the preparation efficiency of process documents, And it can minimize unnecessary human errors

(3) integration of product process design and management from the perspective of enterprise management, the product process management work such as statistical summary of tooling equipment, materials, process key parts, outsourced parts, man hour quota, auxiliary materials, key processes and so on, and the change and filing management of product process documents occupy a very important position; In some enterprises, the repetitive work of summarizing, calculating and copying process data accounts for% of the total workload, which is not what we want to see. Process personnel spend most of their time on repetitive work such as the summary and statistics of process data, which is not only inefficient, but also difficult to ensure the accuracy and consistency of process documents

with the emergence and development of new production methods and philosophies such as CIMS and agile manufacturing, in the environment where enterprises adopt these new technologies in order to enhance market competitiveness and quickly respond to market changes, it is difficult to meet the needs of enterprise information only by realizing the computerization of process planning. In addition to the convenient computer-aided process planning function, it should also include the rapid and effective management of enterprise manufacturing process information and process workflow, realize the integration of product process design and management, and establish a complete manufacturing process information system

2. Manufacturing process information system

in an enterprise, a complete manufacturing process information system should be based on the computer-aided design of various professional processes to realize the process management functions such as basic process information management, manufacturing oriented product structure management, material quota preparation, process division and process design process management, product process data integrated management, as well as the integration and resource sharing with cad/pdm and ERP

v. comprehensive intelligence of CAPP based on knowledge

establishing a manufacturing process information system based on interactive CAPP does not exclude efforts in the direction of CAPP intelligence. On the basis of establishing a rich process knowledge base, applying various artificial intelligence decision-making technologies to achieve various effective intelligent AIDS at all stages is still an important goal of CAPP development

in the early stage of CAPP application in an enterprise, interactive design is the main design method. With the accumulation of process data and knowledge, not only

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