The hottest integrated design for manufacturing

  • Detail

Integrated design for manufacturing

abstract the factors in product design are investigated from the perspective of industrial manufacturing. Concurrent engineering and CAD, as effective means to improve productivity, can play a great role in promoting design innovation and improving the design level of enterprises. At the same time, design should be a flexible process, and the design means should also be more humanized. How to make design better play its role in the whole life cycle of products is a problem we should be concerned about. Rational allocation of resources and the use of advanced means can achieve this goal

keywords concurrent engineering; Serial; DFMA technology; CAD; KBE; The market competition in the 21st century is not only the competition of advanced technology, but also the competition of product design. Product innovation based on knowledge is the core of modern industrial design. With the rapid development of networking and information technology, the competition between enterprises is becoming more and more brutal, and the risk of product development is much greater than before, which puts forward higher requirements for enterprises: the time taken for a product from the initial concept to the completion of manufacturing and then to the hands of users is shorter; The shape and function of the product should meet the needs of the market, and the quality should be good; The manufacturing cost should be as low as possible, and environmental protection should be done as much as possible. Therefore, if enterprises want to remain invincible in the market, they have to speed up the solution of a series of problems in the development of new products, such as understanding market demand, improving product quality, reducing costs and providing quality services. However, in these problems, the key is to quickly develop new products and speed up the time to market. Modern enterprises require agile production, which requires concurrent engineering in the design process, that is, to carry out convenient, fast and safe collaborative design work between collaborative enterprises and departments, and to involve users in the whole process of product development, so as to find product defects, correct them in time, meet user needs, and enhance the core competitiveness of enterprises

Generally speaking, the whole process of product development includes these links: project establishment, market research, design (Industrial Design + structural design + mold design + circuit design +...), process, procurement, manufacturing, inspection, sales, after-sales service, recycling, etc. design is the most important link. Although product design accounts for less than 5% of the total cost of the product, it affects more than 70% of the total cost of the product

the traditional serial product development mode, that is, after the project is approved, the market demand analysis is carried out first, the design department designs the product according to the analysis results, and then submits the drawings and files to the technical department for the preparation of process methods and manufacturing tooling. The purchasing department purchases according to the requirements, and then carries out production, processing and testing after everything is ready. When the product results are not satisfactory, the design and process are repeatedly modified, and then processed and tested, Until the requirements are met, then mass production is carried out. It is not difficult to see that the processes of serial engineering from design to manufacturing are implemented step by step in a certain order. Due to the lack of support and cooperation from other departments in the design of product schemes, many problems that could have been solved in advance must be found after the whole design scheme enters the next link, and then the design department will modify and correct the design according to the feedback results of subsequent departments. In this way, in a certain period of time, some departments are busy while others are too idle, resulting in a waste of time and resources. Moreover, if departments shirk each other when problems occur, it will cause great harm to the competitiveness of enterprises. Because each department always operates independently in product development, especially the requirements of other links are rarely considered in the design, this method often leads to repeated design modifications, which seriously affects the time to market of products

In 1986, the Defense Analysis Institute of the U.S. Department of defense published a very famous r-338 report, which proposed the concept of "concurrent engineering", That is, "concurrent engineering is a systematic method to design products and their related processes (including manufacturing process and collaborative process) in an integrated and parallel way. This method requires product developers to consider all factors from concept formation to product scrapping in the whole life cycle of products from the beginning, including quality, cost, schedule and user requirements". Since entering the 21st century, concurrent engineering has richer connotation and wider extension. It requires that in product design, not only its upstream market requirements and customer requirements, but also its downstream process, manufacturing, maintenance, impact on the environment, and even scrap disposal should be considered, that is, all factors in the whole life cycle of products should be considered at the same time

as shown in Figure 1.1, this is the development mode adopted by concurrent engineering. Practice has proved that concurrent engineering can reduce product costs by 25% to 35%, shorten product launch time by 20% to 90%, shorten product development cycle by 40% to 60%, reduce the number of engineering changes by 60% to 90%, improve overall quality by 200% to 600%, increase annual revenue by 5% to 10%, and increase productivity by 20% to 110%. ④

Figure 1.1 schematic diagram of parallel new product development

DFMA (Design for manufacturing and assembly) technology is an important part of the key technology of concurrent engineering, and its idea has been throughout the enterprise development process. It covers a lot of content, involving the manufacturing, assembly, monitoring, maintenance, scrap disposal and other stages of product development. DFMA technology is applied in the early (conceptual) stage of product design to consider and solve the problems of product assemblability and manufacturability. After many DFMA cycles (see Figure 1.2) 4. Before and after loading the test piece, enter the later detailed design stage, and then prototype manufacturing and mass production. Through this process, although the time of the design phase has been extended, the development cycle of the whole product has been greatly shortened. The cost is saved and the product quality is improved. ①

2 application and development of CAD

CAD technology is a key technology to realize design automation and enhance the competitiveness of enterprises and their products in the market. In the whole design process, the most concerned is the coordination of data transmission and design. In the process of data transmission from conceptual design to structural design to computer model of mold design, many problems often occur due to the data interface between software. Therefore, the most ideal way is that all processes can be completed in one software. In this regard, EDS company has provided us with a good solution. As a large-scale software integrating design and manufacturing, UG NX provides a series of functions from conceptual design, structural design to mold design and manufacturing, which perfectly solves the problem of data interface. Moreover, EDS' relevant software products cover the whole enterprise product process, and can provide good services in the whole product life cycle

2.1 application of CAD

in the process of product design, the most concentrated and prominent stage of innovation is the conceptual design stage of products. When the designer constructs the computer virtual form of the outer surface of the product, he should first construct the outline wireframe model of the product shape on the computer according to the characteristic curve of the conceptual sketch, and carry out the necessary smoothing and optimization treatment on these curves. Using the smoothed curves and considering the forming conditions of the surface, he should select the appropriate surface construction method to generate the product shape surface When constructing surfaces, it is generally required that two adjacent surfaces should maintain tangent continuity or curvature continuity at the common boundary, and the generated surfaces should be smooth

after the mathematical model of the external surface of the product is completed, the tool trajectory should be generated, and the external model of the product should be processed on the numerical control machine tool, and then the model should be modified accordingly according to the requirements of modeling design and ergonomics. Using the coordinate measuring machine, the surface data of the external model should be measured according to the design requirements, and the corresponding point coordinate file should be generated, and then input into the modeling CAD system, Modify the mathematical model of the product surface according to the newly measured data. After the comprehensive evaluation of the model, the mathematical model of the final product surface is generated. ③

Product Structure CAD is to decompose the mathematical model of the whole product surface into the mathematical model of multiple panels according to the needs of product function and manufacturing process. On this basis, the surface design of the fitting surface of panels is carried out. In surface modeling, we should carefully analyze and study the characteristics of the surface, reasonably generate the frame curve of the constructed surface, determine the corresponding relationship between the parameters of each curve, and select the appropriate surface modeling method to meet the needs of modeling design

mold CAD is based on the mathematical model of the product surface provided by the product design department, and according to the process requirements of the part, start the computer-aided design of each process mold. For example, in the design of stamping die, the following important work should be completed: selection of stamping direction, process supplementary surface design, determination of the best pressing surface, stamping forming analysis, etc

2.2 the development of CAD

in recent years, the demand of the market is more and more extensive, and the demand of users is also more and more personalized. In order to meet these new requirements, we need to constantly and real-time modify the design results in the design process. The traditional CAD is not to help designers carry out innovative design, but to make a good design into an entity. In the face of fierce international competition, what enterprises need is not a tool to do better in a certain product detail, but a complete solution. In addition, there are a wide range of people involved in the collaborative design of the whole product, from conceptual design, structural design, mold design to marketing personnel and sales personnel, who all need the same data. If CAD software can use a set of integrated tools to comprehensively solve the problems of conceptual design, part design, assembly equipment measurement and control system, high-precision digital servo valve meter, sheet metal design, and the above are the precautions for the use of mortar tensile testing machine and the operating procedures of the equipment, product real effect simulation and animation simulation, which are shared by the company's technical personnel for everyone, it will greatly improve the design speed

in a sense, conceptual design is the most important aspect of product design, which has a decisive impact on the quality of design results. Therefore, for CAD system, it should not only be able to deal with data information well, but also be able to deal with knowledge information. Expert system, a branch of artificial intelligence, provides a powerful means to realize the above intelligent behavior of non numerical calculation on computer. Expert system is a system using computer intelligent program. It has a lot of knowledge and experience in the field of expert level. It solves the problems in the design by reasoning and judging, simulating the methods of experts to solve the problems, and perhaps unloading the process in the loading process

three problems should be solved in establishing an expert system of engineering design

(1) knowledge acquisition - how to extract the knowledge and reasoning methods of human experts

(2) knowledge representation - that is, how to transform the acquired knowledge into appropriate logical structure and data structure and store it in the computer

(3) use of knowledge - that is, how to design reasoning mechanism to use knowledge to solve problems

integrate AI technology, especially expert systems

Copyright © 2011 JIN SHI