The new stage of CAPP development and intelligent

2022-07-23
  • Detail

The new stage of CAPP development and the conception of intelligent process information system Abstract: This paper analyzes the main problems existing in the current CAPP technology, such as one-sided goal, narrow scope and insufficient attention to engineering, and puts forward the conception of process information system and CAPP methodology for the whole product. The key technologies are discussed, and the research and development work in recent years are introduced

key words: CAPP intelligent process information system CAPP for the whole product

preface

computer aided process planning (CAPP) is a bridge connecting CAD and cam, and one of the technical foundations of many advanced manufacturing systems. Therefore, since the birth of CAPP Technology in the late 1960s, its research and development has been booming at home and abroad, and gradually attracted more and more attention. Unfortunately, although many achievements have been made in various decision-making methods, machining process CAPP, intelligence and integration at home and abroad, the application foundation is not very solid, and the research and development direction is far from the current actual demand. In recent years, with the development of computer integrated manufacturing system (CIMS), concurrent engineering (CE), intelligent manufacturing system (IMS), virtual manufacturing system (VMS), agile manufacturing (AM) and other advanced manufacturing systems, both in breadth and depth, Both put forward newer and higher requirements for the development of CAPP

obviously, CAPP has reached a new stage of development. In order to meet all kinds of new challenges, in recent years, we have put forward some new ideas, such as the CAPP system for the whole product (hereinafter referred to as product oriented) and the more generalized computer-aided process planning and management system, that is, intelligent process information system (IPIs). We have developed some CIMS Engineering requirements for some enterprises, and also launched software products

1 current problems of CAPP technology

up to now, a large number of funds and forces have been invested in the research and system development of CAPP technology at home and abroad, and a large number of CAPP systems have been developed. In the developed CAPP system, some systems have been applied in practice, and a few have been commercialized. But on the whole, there is a serious deviation in the research and development direction of CAPP. From the perspective of application, the actual benefits obtained are not commensurate with the input; The key research directions at home and abroad are far from the current actual needs. Performance: more development, less application; There is a lot of investment in development and almost no investment in application maintenance; There are many prototype systems, but few systems have been used in actual production; There are few commodity systems with insufficient functions; Compared with CAD, cam, MIS, PDM and other related computer-aided technologies, the gap is quite large. The reasons can be summarized as the following aspects

① the goal of CAPP research and development is one-sided.

for a long time, the goal of CAPP has been to develop an automation system instead of an auxiliary system to replace process personnel, that is, it overemphasizes the automation of process decision-making. Although the 'automatic' CAPP system developed under the guidance of this goal integrates the knowledge and experience of human experts, it usually requires users to input part information interactively in a time-consuming and laborious manner according to the specified description method (although many systems have realized cad/capp integration technically, they are far from Engineering), and then the system makes automatic decisions. Generally, it only provides a simple man-machine interface, and the effective participation of people is rarely considered in the decision-making process. This leads to the following problems:

the system development cycle is long, the development cost is high, the development is difficult, it is difficult for users to participate, the applicability is poor, and it is difficult to promote the application

it is difficult for the process personnel to master the use of the system, and a large amount of information still needs to be input interactively in use, which is troublesome and error prone

process design and management cannot be integrated, which not only leads to low work efficiency, but also makes it difficult to ensure the accuracy and consistency of process information and documents

capp research and development can only take parts as the main object, and is often carried out for specific manufacturing objects, specific manufacturing environments (specific enterprises, specific workshops and even specific equipment). The developed system has limited functions and application scope (with great limitations), and lacks flexibility and applicability to adapt to changes in production environment

in order to solve the above problems, the development of CAPP development tools and the application of object oriented (O-O) technology have been explored at home and abroad, but the problem has not been solved due to the fact that automation is the goal and parts are the main object. This situation is not only difficult to meet the growing demand for the application and development of CAPP in advanced manufacturing systems, but also is bound to cause a lot of repeated labor and waste of human, financial and material resources, which seriously limits the breadth and depth of CAPP application

② the application scope of CAPP system is too narrow

* supported by the aviation basic science foundation

due to the complexity of the problems involved in the CAPP system and its dependence on the application environment, and because the goal of decision-making automation is set too high, the research and development of CAPP basically focuses on parts, and is mainly concentrated in the field of machining process design. Each system is only applicable to a few parts. It is generally believed that it is difficult or even impossible to develop a universal system, but the universality and universality of the basic data structure and basic design functions of the process are not recognized

this lack of research on the application and integration of CAPP from the perspective of the whole product, and the neglect of the research and development of process management functions, is difficult to apply to most parts in enterprises, and is even more difficult to meet the application and development needs of advanced manufacturing systems. Even in enterprises where computers are widely used, they will lose their due important value

③ not enough attention is paid to the systematic, practical and Engineering Research of CAPP

although various new concepts, new methods and new technologies are continuously applied in CAPP, they are mainly aimed at various decision-making functions, and there is always a lack of systematic, practical and Engineering Research on CAPP, and the integration between various technologies, technologies and management, and people, making these new technologies, new concepts and new methods play a very small role, It also makes the overall development of CAPP lack of solid practical foundation and power. In recent years, both at home and abroad have begun to realize the impact of CAPP application and engineering problems on CAPP development. For example, maraghy pointed out that the application of CAPP in enterprises has lagged behind the application of new concepts and the development of new systems [1]. We feel that this has almost become a stumbling block to the current CAPP development

④ the basic technologies and methods of CAPP need to be further studied.

process design is a typical complex problem, which includes various functional requirements of different natures such as analysis, selection, planning and optimization. It involves a wide range, uses a large amount of information, and is closely related to the specific production environment and personal experience level; Different production environments (different factories, even different workshops in the same factory), different product objects, different production batches, different production equipment, process methods and process habits make great differences in product processes. For a long time, the research and developers of CAPP have neglected the in-depth research and exploration of general basic technologies, methods and data involved in process design. The adoption of various new concepts, methods and technologies lacks both application foundation and systematic foundation. M he believes that the lack of good theory and solid scientific foundation of process design method is the factor that hinders the development of CAPP [2]. In the 1990s, the importance of basic theory and method research of CAPP has been increasingly recognized at home and abroad. Ng he believes that the basis of developing CAPP system is the principle and method of process design, and points out that some researchers overemphasize the importance of computer programming in CAPP system development and ignore the principle and method of process design, so it is impossible to develop a high-level CAPP system [3]

looking at the development of advanced manufacturing technology and advanced manufacturing system, we can see that the future manufacturing is based on integrated and intelligent agile manufacturing and "globalization" and "Networking" manufacturing, the future products are based on information and knowledge, and the intelligent, integrated and wide application of CAPP is the premise of realizing the informatization of product process, It is one of the key links to realize the whole process integration of product design and manufacturing. Proceeding from the development strategy and national conditions of China's advanced manufacturing technology, the development of CAPP should, on the premise of conforming to the development trend of new technology, conduct in-depth research on the product oriented (whole product oriented) CAPP Integration (including process information management), intelligence and engineering technology from a systematic perspective; We should put more emphasis on the market demand and put enough effort into the development of engineering and commercialized software to push the research and development of CAPP technology to a new stage

next, we will briefly discuss our new idea and its technical points

product oriented CAPP Integrated and intelligent concept system and key technologies

2.1 product oriented CAPP and IPIs

2.1.1 product oriented process design and process information system

in modern mechanical manufacturing industry, product process design has multi-level and multi-stage characteristics. We can divide the product oriented process design into two levels, namely, overall process design and special process design. At different stages of the product life cycle, the documents generated by the above process design will have different versions and contents. In addition to process management, the process information system will include the following contents:

① the overall process design mainly includes the following contents:

⑴ product structure process review

⑵ division of product process components

⑶ formulation of product process flow (also known as division plan)

② special process design in general product manufacturing, the types of special process design include:

⑴ blank manufacturing (including casting, forging, blanking, welding, etc.) process design, part processing (including various machining, sheet metal stamping, etc.) process design, etc

⑵ process design of various heat treatment and surface treatment

⑶ welding, assembly and other process design

⑷ other process design such as detection and test

③ process information management

from the perspective of enterprise management, various statistical summary functions such as tooling equipment, materials and auxiliary materials, outsourced parts and man hour quota, as well as product process management such as archiving and changing of different versions of process documents, tooling and tool documents at various stages of various products, occupy a very important position; In some enterprises, the repetitive work such as process data collection, calculation and copying accounts for% of the workload. With the generation of various basic process data and document management, the process management work accounts for about 80% of the total workload. The process personnel spend most of their time on the summary, statistics and repeated filling of process data, which is not only inefficient, but also difficult to ensure the accuracy and consistency of process information and documents. Therefore, product oriented process information management should also be an important part of the overall process. With the development of PDM (Product Data Management), VM, am and other advanced manufacturing technologies, product process version update and control, process design process control, BPR based(

Copyright © 2011 JIN SHI