机械设计制造及自动化毕业设计英文翻译资料Word文档下载推荐.docx

1、This paper presents a novel integrated system of rapid product development for reducing the time and cost of product development. The system is composed of four building blocks digital prototype, virtual prototype, physical prototype and rapid tooling manufacturing system. It can aid effectively in

2、product design, analysis, prototype, mould, and manufacturing process development by integrating closely the various advanced manufacturing technologies which involve the 3D CAD, CAE, reverse engineering, rapid prototyping and rapid tooling. Furthermore, two actual examples are provided to illustrat

3、e the application of this integrated system. The results indicate that the system has a high potential to reduce further the cycle and cost of product development.Keywords: Rapid product development; rapid prototyping; integrated system.1. IntroductionDue to the pressure of international competition

4、 and market globalization in the 21st century, there continues to be strong driving forces in industry to compete effectively by reducing manufacturing times and costs while assuring high quality products and services. Current industries are facing the new challenges: quick response to business oppo

5、rtunity has been considered as one of the most important factors to ensure company competitiveness; manufacturing industry is evolving toward digitalization, network and globalization. Therefore, new products must be more quickly and cheaply developed, manufactured and introduced to the market. In o

6、rder to meet the demand of rapid product development, the various new technologies such as reverse engineering （RE）, 3D CAD, rapid prototyping （RP）, and rapid tooling （RT） have emerged and are regarded as key enabling tools with the ability to shorten the product development and manufacturing time.

7、For example, it has been claimed that RP can cut new product development costs by up to 70% and the time to market by 90%.1 In the form of a better design, more design possibilities, a 3D CAD model can be shown to the customer for approval and prevents misunderstandings. A virtual prototyping is emp

8、loyed to guide in optimization of the product design and manufacturing process planning, which may result in the accurate determination of the process parameters, and reduce the number of costly physical prototype iterations. Rapid tooling technique offers a fast and low cost method to produce mould

9、s, and shows a high potential for faster response to market demands. When properly integrated among 3D CAD, CAE, RE, RP and RT, these technologies will play a much more important role to reduce further the development cycle and cost of the product production. On the basis of above technologies, a no

10、vel integrated system of rapid product development is to be founded so as to meet the requirement of rapid product development.2. Architecture of the Integrated Development SystemThe development process from initial conceptual design to commercial product is an iterative process which includes: prod

11、uct design; analysis of performance, safety and reliability; product prototyping for experimental evaluation; and design modification. Therefore, any step of the new product development process has a direct and strong influence on time-to-market in short order. A good product development system must

12、 enable designers or design teams to consider all aspects of product design, manufacturing, selling and recycling at the early stage of the design cycle. So that design iteration and changes can be made easily and effectively. The more fluent the feedback is the higher possibility of success the sys

13、tem has. Design for manufacturing （DFM） and concurrent engineering （CE） necessitate that product and process design be developed simultaneously rather than sequentially. The integrated system of rapid product development is composed of four modules: digital prototype, virtual prototype, physical pro

14、totype and rapid tooling.The product development starts from the creation of a 3D CAD model using a CAD software package. At that stage, the product geometry is defined and its aesthetic and dimensional characteristics are verified. The main function of digital prototype is to perform 3D CAD modelli

15、ng. The CAD model is regarded as a central component of the whole system or project information base which means that in all design, analysis and manufacturing activities the same data is utilized. The product and its components are directly designed on a 3D CAD system （e.g.Pro/Engineer, Unigraphics

16、, CATIA, IDEAS, etc.） during the creative design. If a physical part is ready, the model can be constructed by the reverse engineering technique. RE is a methodology for constructing CAD models of physical parts by digitizing an existing part, creating a digital model and then using it to manufactur

17、e components. RE can reduce the development cycle when redesigns become necessary for improved product quality. Preexisting parts with features for improved performance can be readily incorporated into the desired part design. Therefore, it is very useful in creating the CAD model of an existing par

18、t when the engineering design is lost or has gone through many design changes. When a designer creates a new design using mock-up, it is also necessary to construct the CAD model of the mock-up for further use of the design data in analysis and manufacturing. The three primary steps in RE process ar

19、e part digitization, features extraction, and CAD modelling. Part digitization is accomplished by a variety of contact or non-contact digitizers. There are various commercial systems available for part digitization. These systems range from coordinate measuring machine （CMM）, laser scanners to ultra

20、sonic digitizers. They can be classified into two broad categories: contact and non-contact. Laser triangulation scanner （LTS）, magnetic resonance images （MRI）, and computer tomography （CT） are commonly used as non-contact devices. Contact digitizers mainly have CMM and cross-sectional imaging measu

21、rement （CIM）. Feature extraction is normally achieved by segmenting the digitized data and capturing surface features such as edges. Part modelling is fulfiled through fitting a variety of surfaces to the segmented data points.In order to reduce the iterations of design-prototype-test cycles, increa

22、se the product process and manufacturing reliability, it is necessary to guide in optimizing the product design and manufacturing process through virtual prototype （VP）. VP is a process of using 3D CAD model, in lieu of a physical prototype, for testing and evaluation of specific characteristics of

23、a product or a manufacturing process. It is often carried out by CAE and virtual manufacturing system. Computer aided engineering （CAE） analysis is an integral part of time-compression technologies. Various software tools available （i.e. ANSYS, MARC, I-DEAS, AUTOFORM, DYNAFORM, etc.） can speed up th

24、e development of new products by initiating design optimization before physical prototypes are built. The CAD models can be transferred to a CAE environment for an analysis of the product functional performance and of the manufacturing processes for producing the products components. It has also pro

25、ven to be of great value in the design optimization of part geometry, to determine its dimensions and to control warpage and shrinkage while minimizing process-induced residual stresses and deformations. Virtual manufacturing system （VM） is the natural extension of CAE. It simulates the product func

26、tionality and the processes for producing it prior to the development of physical prototypes. VM enables a designer to visualize and optimize a product process with a set of process parameters. The visualization of a virtually simulated part prior to physical fabrication helps to reduce unwanted pro

27、totype iterations. Therefore, a product virtual manufacturing system may result in accurate determination of the process parameters, and reduce the number of costly physical prototype iterations. 3D CAD model and VP allow most problems with unfitting to become obvious early in the product developmen

28、t process. Assemblies can be verified for interference as VP can be exercised through a range of tasks. Structure and thermal analysis can be performed on the same model employing CAE applications as well as simulating down-stream manufacturing processes. It is clear that VP increases process and pr

29、oduct reliability. Although VP is intended to ensure that unsuitable designs are rejected or modified, in many cases, a visual and physical evaluation of the real component is needed. This often requires physical prototype to be produced. Hence, once the VP is finished, the model may often be sent d

30、irectly to physical fabrication. The CAD model can be directly converted to the physical prototype using a RP technique or high-speed machining （HSM） process. The 3D CAD model is to be exported not only in the STL format which is considered the de facto standard for interfacing CAD and RP systems, b

31、ut also in the NC coding which can be used by HSM. HSM has a potential for rapid producing plaster or wooden pattern for RT. RP is a new forming process which fabricates physical parts layer by layer under computer control directly from 3D CAD models in a very short time. In contrast to traditional

32、machining methods, the majority of rapid prototyping systems tend to fabricate parts based on additive manufacturing process, rather than subtraction or removal of material. Therefore, this type of fabrication is unconstrained by the limitations attributed to conventional machining approaches. The a

33、pplication of RP technique as a useful tool can provide benefits throughout the process of developing new products. Specifically, there are serious benefits that RP can bring in the areas of market research, sales support, promotional material, and the ever-important product launch. Physical RP can als