机械毕业设计英文外文翻译241基于网络的快速原型制造

附录一基于网络的快速原型制造

摘要：这篇论文提出了新的基于快速原型快速产品开发集成系统,发展了通过充分利用迅速发展的计算机网络和信息技术的网络制造服务系统,这个系统

提供更好的在中小型企业中对于快速产品开发的支持。提出了制造业的网

络化服务体系的架构。此外,一些关键问题,包括模型、规划制造链,选择

可行的合作厂家,排列制造任务,利用同步协作的工作环境,建立一个适合

管理平台等问题得到了论述。可运行java的解决办法与网络技术,用于建

立这样一个网络服务系统。最后提供了一个这种服务的应用系统的实例。关键词：快速原型制造、服务系统

1．简介

这是信息技术时代. 信息技术影响社会各领域,并且大大影响了传统工业。现代企业正面临新的挑战:快速反应的商机——一直被视为以保证公司的竞争力最重要的因素之一；制造业发展走向数字化、网络和全球化.。为了有效的响应变化，生产策略，根据市场情况和客户需求在时时变化。任何改变策略,应该使厂商更能自己有能力应付这样的需求,减少生产时间,提高质量和速度,能够为全球客户提供优质的产品，改善交通运输系统[1]。这是既定的事实,在设计和制造中利用计算机为获得很大的工业生产力的提供了最重要的机会。未来制造业组织将是信息化,知识驱动和依据联系到每个人的全球信息网络自动化的自动控制，目前已被广泛认同。为了满足产品快速发展的需求,各种新技术,如逆向工程(RE)、快速Prototyping(RP),快速工具制造(RT)等出现了,并且被视为能够缩短产品研制时间和制造是键的有利工具。例如,有人说RP可以节省新产品开发费用到70%和市场时间的90%。但是,这些设备对中小型企业(SMEs) 都太贵,并且许多技术比如3D固体模型、RP规划过程,自由形式表面重建等,都需要高技能人才来完成。因此,对中小企业在产品开发过程充分利用这些技术是特别困难的。为了大量中小企业的产品快速制造得到发展提供支持, 许多RP事务局(SBS),不仅可以制造物理原型、快速原型工具，还提供其它的工程服务,已建立起来。到2001年, 世界各地有500多个SBS。但并不是需要每个SB能处理所有的设计和制造能力,但必须有效运用外部资源,以更好地满足客户的需求。即通常定义为一个临时联合企业的以计算机网络支持的虚拟企业将被建立。他们是为了满足商机一起分享他们的技能、核心能力和资源,。每个SB处理自己的核心任务,并且需要大量的合作伙伴来完成其它这个SB不能按时完成的工作。强调服务质量的新思路,变成一个制造业在21世纪赢得全球竞争的基本方略。远距离服务是一个针对厂商和顾客“服务”问题的新兴领域。因为数字制造业技术进步很快,数字服务将没有阻碍的进入综合数字系统设计和制造。结合计算机和多媒体的因特网，为商业和制造业的远程融合和协作提供了巨大的潜力。对于SBs和SMEs，完成网络制造平台，来加速生产效率是非常紧迫的。这篇论文的其他部分组织如下：1.在第二部分回忆了相关的研究工作2.在第3部分,我们介绍一个基于RP的完整的得到快速发展的系统。第四部分叙述网络制造服务体系的了流程及功能设计。第5部分介绍系统运行平台配置。第6部分我们讨论了互联网应用设计。第7部分研究了案例。最后,第8部分是论文的总结。

2 、相关的研究

伴随着计算机网络和信息技术的发展,网络制造技术在制造业中发挥着越来越重要的作用。近年在世界各地来自学术界和工业团体为支持网络制造的研究与实践(或全球制造或者远程制造)作了大量投资。一些战略和框架已经提出。Abdel-Malek等[8]描述了一个架构,让公司可以把一些生产和设计活动,通过互联网发展模式,以协助公司选择可替代的技术和功能,最大限度地发挥灵活性。Montreuil等[9]提出了一个战略框架,提出了设计和制造灵活的经营网络,以动态掌握使合作计划、控制和管理日常的环境。Tso等介绍了代理式的协作支持服务系统, 通过专门设计一些虚拟代理信息网络，能够满足制造服务的要求。Chen 等[11]提出了基于网络设计与制造的综合框架,是基于java和CORBA技术的。Offodile和Abdel-Malek 利用虚拟制造模式将制造业和信心产业融合的战略框架。Huang等提出了对于虚拟企业架构和控制机制的框架。O’Sullivan[14]描述了信息结构及相关资料,来了解和处理商业发展。Akkermansa和HORSTC[15]讨论了信息技术基本标准化公司的管理方并指出了战略框架以指导管理者基于一些原有的经济与管理理论作出明智的决定,如交易费用理论、组织设计和成熟发展阶段。Jin等[16]提出研究和关键技术的应用解决方案,其中包括确保网络数据在成员之间传输的安全策略；基于Web/Dotd的数据管理(分布对象技术)、XML标准，能够保证不同结构环境的数据交换；提供各类服务转换文件的网络平台。 Woerner和Woern网络服务提出了新的发展平台，提供了虚拟工程合作生产的方法。

为了充分认识当今全球化的制造业的远程工程及当前市场形势和客户需求,一些全球生产网络已经建立,其中包括在社会生产工程师、LockheedMartin(AIMSNET)[19]、3M(3M创新全球网络)。

今天的产业正面临严重的其快速发展所带来的全球海外活动集成制造环境的结构性问题,。服务和维修对于公司保持制造业生产力及国外地区客户满意变得极为重要。由于传统服务台的固有问题,一些公司已开始发展网上在线客户服务支撑体系。Foo等综合描述客户服务台对于互联网服务的支持。Lee讨论了远程服务系统设计制造设备和产品支持的概念框架和生命周期。已建立的示范远程客户支持系统FCSA证明了Glober的项目。以上这些体系的目的是为有效满足客户在使用远程支持、维修设备。

加州大学研究和发展项目,称为远程制造厂(TMF)是建立在因特网上的自动快速生产。用户可以使用TMF提供就业机会,并维持系统自动排队。同时可以自动检查StL的许多缺陷。在设计和制造过程中使用RP技术可能带来巨大的好处。但是,需要有效地利用这些好处,这些好处才能得到完全的开发。对全球RP技术有一个了解是非常困难的。因为很快出现了一些新的改进方面的工作。为了帮助选择合适的快速制造过程, 已经开发了许多快速原型系统选择工作。https://www.360docs.net/doc/ef4587106.html,,这是一个私人拥有制造服务公司致力于提供客户网上电子商务系统用于采购量低、高生产量关税地区,并形成了一种系统QuickQuote。QuickQuote让顾客得到为生产部件的快速的报价。3D系统公司是最早、最大的RP制造商,提供了通过互联网的服务。

从这些调查的文字,显然大部份的研究主要集中在战略和总体结构网络制造以及个别功能模块,还没有一次全面comprebanausic网络制造和服务体系,支持快速的产品开发。基于我们以前的工作,及新的研究,以网络为基础的生产服务体系的产品迅速开发将被建立。

3 、快速制造的综合系统结构

从最初的概念设计到产品的商业性的发展过程包括:产品设计; 性能分析，安全性和可靠性; 对产品原型试验评价; 设计和修改。因此,新产品开发的每一步进程对产品市场化时间产生直接影响。一个好的产品开发体系,使设计师或设计小组必须考虑各方面的产品设计、制造、销售、回收初期的设计周期。因此,设计制作可轻易改变并有效。反馈越流畅,该系统成功的可能性越高。设计制造(DFM)和并行工程(CE)要求产品设计和开发过程,同时得到发展，而不是按顺序。

产品快速发展的综合系统由三个单元组成:数字原型、物理原型和快速制造装备与系统功能系统。产品开发利用3维CAD软件制造3D立体模型开始。在这一阶段,产品几何形状得到定义，它在美学上，尺寸上是多种多样的。数字原型的主要功能是完成3D模型。在设计创作过程，产品及其部件在3D CAD系统上直接设计(如Pro/E、Unigraphics、CATIA、IDEA等)。如果实体零件可用, 模型可用逆向工程技术建造的 (RE)。RE一种利用现有零件建立物理模型的方法,建立数字模型,然后用它来制造部件。如果为提高产品的性能而再设计,RE能减少开发周期。当设计师采用模拟创造了一个新的设计,还要进一步利用数据分析和设计制造制造模拟模型。逆向工程的三个主要步骤是数字化特征提取、特征扩展、3维 CAD模型。完成零件数字化的仪器可以是接触和非接触式。有各种商业化的数字化仪。从测量系统,协调机(CMM)、激光扫描机,到超声波仪。它们可分为两大类:接触和非接触式。激光扫描三角(LTS)、磁共振影像(MRI)、计算机断层(CT)是常用的非接触式的装置。接触式的主要有CMM和截面图象测量(CIM)。特征提取通常是通过数据捕捉和捕捉表面特征。零件模型是通过填充适当的数据面完成的。为了减少重复设计原型试验周期、提高生产过程,并增加机器的可靠性,必须通过CAE指导生产,优化设计和制造过程。

CAD模型可以利用RP直接转化为实际的原型。RP是一个新的成型零件制造过程,是通计算机控制一层层的堆积，是直接从3D模型在很短的时间内完成的。与传统加工方法相反,多数的快速原型制造系统基于堆积过程,而非材料切除。因此,这种方法不受规机械加工限制因素的限制常。在设计和制造过程中使用RP 可能带来巨大的好处。可以缩短产品市场化时间、降低成本和提高质量。过去10年来,已广泛应用于工业领域。主要的商业化RP技术包括业stereolithgraphy(ST)selectivelasersintering(SLS),融合沉积制造(FDM)、胶合物体制造(LOM)、弹道微粒制造(BMP)、三维印刷(3D印刷)等。

RT是一种技术,把RP零件转化为功能部件,特别是金属零件。此外, RP、RT 的融合推动了公司并行工程的发展。许多由RP系统制造模具的生产过程得到发展。RT的方法大致可分为直接和间接的,软、硬切削的。间接RT需要掌握某种模式,这种模式可以由常规方法(HSM等)获得,或者由RP，SL，SLS获得。直接RT,顾名思义,是直接由RP系统制造的,从而消除了中间产生步骤格局。根据上述技术、新产品开发的综合系统将迅速建立起来。详细结构如图1。

4、工作流程和功能设计

工作流程的生产服务体系网络如图2。第一步是登陆SB网站。用户用自己的名称和密码进入。那些没有登记或核准可以进入系统的,只限于观看资料,例如这一系统公开的'典型案例'。进入用户的密码将有系统验证。进入网站成功之后,系统会自动核对使用者的安全程度,确定哪些模块可以进入或使用。根据认证的制度,所有用户可分为四类:一般用户(未注册)、潜在客户,真正的客户,系统管理员。接受客户要求后,SB将首先进行规划过程的任务分解落实,并选择最合适的加工方法。在上未做后续工作之前，用户必须得到产品的排队和初步生产时间。如果可以接受这样的结果,在最初阶段,SB进一步与用户进行了电视会议。当对方确认合同,用户成为真正的客户。用户提出的生产任务将由SB做到最好的实施。

但是,如果SB没有这样的制造能力,或不能按时完成, 充分利用外部资源来源进行未完成的任务，是一个有效的方法。下一步就是选择合适的合作厂商,形成虚拟企业依靠分配制度完成任务的工作。此外,为了监测安排,以确保生产的顺利生产,用户与合作生产企业,必须尽快实现基本信息、生产进度时间表的生产监管。所以落后或不符合质量标准任何公司,将受到严格审查,及时采取预防和补救措施,提前预测损害。

提到上述流程网络化服务体系和数字远程服务体系功能要求，服务体系包括九个功能模块:技术研究、典型案例、信息咨询、协议(应用服务提供者)一套工具,客户管理、电子商务、制造服务、导航系统。详细结构见图3。

这九个部分无阻碍的共同努力实现共同目标,即以提供及时有效的服务和产品平台,以支持中小企业发展迅速。其中一个目的是研究技术,使用户能更加了解相关的知识产品的快速发展。为了帮助读者更好地了解和运用这些新技术，系统说明一些真实案例。技术研究和典型案例的主要提供自助服务的用户。根据专家支配,SB能回答客户的问题并且有与用户沟通解决问题的信息咨询模块。

ASP了五项有用成分组成如下: RE/RP/RT的进程规划,STL检查和维护,零件优化控制, 生产结构支撑、零件优化计算。逆向工程方法有多种,除了以前描述的RP和RT,每种都有其特点和适用范围。按个别情况和任务的要求，选择最合适的加工方法时非常困难的。根据ASP模式有3种选择器,即“RE selector”、“RP selector”、“RT selector”。 StL固体模型之建立,减少约10%的时间。这表明自动检查错误所有其它重要的业务对于RP控制室非常重要的。根据我们提供网络资源的经验,我们知道, 在没有设计者的网站进行错误自动检查时是特别重要的。在某些情况下我们已经制定了各种算法发现自动拓扑与几何修补缺陷。有两个'防火墙'发现这些缺陷:一是结合用户操作。另外就是服务器后台的管理。由于功能定位比较狭窄, StL如果有有致命缺陷或者移交期间失去部分档案资料,就必须再从客户选择材料。组成部分在制造过程中的质量策划可以用的方法有很大的不同。

5 结论和未来研究

为了满足目前对快速产品开发集成系统的需求, 提出了一种新的基于快速原型快速制造融合系统, ,提出了更好的适合中小型企业的产品快速发展的网络服务系统。一种方法是用JAVA制造网络化服务体系建设的基础上建造三层浏览器/服务器模式。自java引入这项技术,可以很容易扩展到基础设施标准。服务体系包括技术信息平台、电子商务平台、制造服务平台,提供了生产协作环境和

用户服务局,使得部分制造资源有效地帮助中小型企业产品快速发展。

附录二 A web-based manufacturing service system

for rapid product development

Hongbo Lan a, Yucheng Ding a,*, Jun Hong a, Hailiang Huang b, Bingheng Lu a Abstract

This paper proposes a novel integrated system of rapid product development based on rapid prototyping, and develops anetworked manufacturing service system which offers better support for the rapid product development in small and mediumsized enterprises by taking full advantage of the quickly evolving computer network and information technologies. The architecture of the networked manufacturing service system is presented. Furthermore, some of the key issues, includingmodelling and planning a manufacturing chain, selecting feasible collaborative manufacturers, queuing a manufacturing task, using the synchronously collaborative work environment, and constructing a suitable running platform, are described in detail. Java-enabled solution, together with web techniques, is employed for building such a networked service system. Finally, an actual example is provided illustrating the application of this service system.

Keywords:

Rapid product development; Rapid prototyping; Service system; Web-based application

1. Introduction

This is the era of information technology. Informationtechnology has influenced every realm of society, and dramatically impacted on the traditional industry.Current industries are facing the new challenges:quick response to business opportunity has been consideredas one of the most important factors to ensurecompany competitiveness; manufacturing industry isevolving toward digitalization, network and globalization.In order to respond to the change effectively,manufacturing strategy has to be modified from timeto time in accordance with the market situation andcustomer demand. Any change of strategy should enable manufacturers to be better equipped themselves,with capabilities to cope with demands suchas a faster response to market changes, a shortenedlead time of production, improved quality and speed,the ability to deliver quality products to global customers,and improved communications and transportationsystem [1]. It is an established fact that the useof computers in design and manufacturing constitutesthe most significant opportunity for substantial productivitygain in industry. It has now been widelyaccepted that the future of manufacturing organizationswill be information-oriented, knowledge drivenand much of their daily operations will be automatedaround the global information network that connectseveryone together [2]. In order to meet the demand ofrapid product development, various new technologiessuch as reverse engineering (RE), rapid prototyping (RP), and rapid tooling (RT) have emerged and areregarded as enabling tools with abilities to shorten theproduct development and manufacturing time. Forexample, it has been claimed that RP can cut newproduct development costs by up to 70% and the timeto market by 90% [3]. However, these equipments aretoo expensive for the small and medium sized enterprises(SMEs), and many techniques such as 3D CADsolid modelling, RP process planning, free-form surfacesreconstruction, etc., require the high skilled personnelto complete. Therefore, it is especially difficultfor the SMEs to take full advantage of these technologiesin the product development process. In order tooffer the support of rapid product development fornumerousSMEs,manyRPservice bureaus (SBs)whichcan not only manufacture physical prototype and rapidtooling but also provide other engineering services,have been established. By 2001, there are more than500 SBs all over the world. But not every SB canpossess all design and manufacturing capabilitiesrequired, it must employ effectively the externalresource to better satisfy client requirements. Namely,a virtual enterprise which usually defined as a temporaryalliance of enterprises that come together to sharetheir skills, core competencies, and resource in order tobetter respond to business opportunities, whose cooperationis supported by computer networks [4–6], is tobe founded. Every SBconducts only the tasks of its corecompetencies, and depends on numerous partners tocarry out the remaining tasks that this SB has no such manufacturing capabilities to accomplish in time.While a new thought emphasizing service quality is becoming a basic strategy by which manufacturing industries can

win global competition in the 21st century. Teleservice engineering is an emerging fieldwhichaddresses ‘‘service’’ issue for manufacturers and customers. As digital manufacturing technique progresses quickly, digital service will be integrated seamlessly into the digital design and manufacturing system [7]. The internet, incorporating computers and multimedia, has provided tremendous potential for remote integration and collaboration in business and manufacturing applications. In order to provide a production collaborative environment for many SMEs and SBs to implement the networked manufacturing, it is especially urgent for many SBs and SMEs to construct a service platform of networked manufacturing to speed up the product development process of the SMEs.

The rest of this paper is organized as follows.Related research work is reviewed in Section 2. In Section 3, we introduce an integrated system of rapid product development based on RP. Section 4 describes the workflow and functional design of the networked manufacturing service system. The configuration of system running platform is presented in Section 5. In Section 6, we discuss the design of internet application. A case study is demonstrated in Section 7. Finally, Section 8 concludes the paper.

2. Related research

With the development of computer network and information technologies, the networked manufacturing techniques are playing a more and more important role in manufacturing industry. Substantial investments have been made to support the research and practice of networked manufacturing (telemanufacturing or global manufacturing) from both the academic community and industrial bodies all over the world in recent years. A number of strategies and frameworks have been proposed. Abdel-Malek et al. [8] described a structure within which a company can outsource several of its production and design activities via internet and developed a model to aid a company in selecting among the available technological and functional alternatives to maximize its flexibility. Montreuil et al.

[9] presented a strategic framework for designing and operating agile manufacturing networks, enabling to collaboratively plan, control and manage day-to-day contingencies in a dynamic environment. Tso et al. [10] introduced the architecture of an agent-based collaborative service support system, which is able to carry out service requests in a manufacturing information network through some specially designed virtual agents. Cheng et al. [11] put forward an integrated framework for web-based design and manufacturing which is developed based on Java solution and CORBA-ORG broking technologies. Offodile and Abdel-Malek [12] introduced a framework for integrating IT and manufacturing strategies using the virtual manufacturing paradigm. Huang et al. [13] presented a holonic framework for virtual enterprises and control mechanisms of virtual enterprises under this framework. O’Sull ivan [14] described an information architecture and associated toolset for understanding and managing the process of business development. Akkermansa and Horstc [15] discussed managerial aspects of information technology infrastructure standardisation in networked manufacturing firms and

presented a strategic framework to guide managers in making sensible decisions regarding IT infrastructure standardisation, based on a number of pre-existing economic and management theories, such as transaction cost theory, organisational design and IT maturity growth stages. Jin et al. [16] presented a research on key application technologies and solutions, which includes a network safety strategy which ensures data transfer among the leaguer members; production data management based on Web/DOT (distributed object technology) and XML criteria which ensure data exchange in structure-variance characteristic environments; the network platform which provides the conversion service of different types of CAD files. Woerner and Woern [17] introduced a new web service based platform providing developed methods for co-operative plant production within virtual engineering.

To full realize the teleservice engineering in today’s globalized manufacturing industry and meet the current market situation and customer demand, a number of global manufacturing networks have been established by, among others, the Society of Manufacturing Engineer [18], Lockheed Martin (AIMSNET) [19] and 3M (the 3M Innovation Global Network) [20].

Today’s industries are facing serious structural problems brought about by their rapid development of overseas activities under a global integrated manufacturing environment. Service and maintenance are becoming extremely important practices for companies to maintain their manufacturing productivity and customer satisfaction in foreign regions. Due to the inherent problems of traditional help desk support, some companies have started developing web-based online customer service support system. Foo et al. [21] described an integrated help desk support for customer service via internet. Lee [7] discussed the concept and framework of a teleservice engineering system for the life cycle support of manufacturing equipment and products. A system for remote customer support has been created in the FCSA demonstrator of the Globerman 21 project [22]. The purpose of these systems above is to provide effective and responsive remote support to customers in the use, maintenance and troubleshooting of their equipment.

University of California is studying and developing a project called the Tele-Manufacturing Facility (TMF) which is to create an automated RP capability on the Internet. TMF allows users to easily submit jobs and have the system automatically maintain a queue. While it can automatically check many flaws in .STL files, and in many cases, fix them [23]. RP potentially offers great benefits when used during the design and manufacturing process. However, RP must be used in an effective manner if these benefits are to be fully exploited. The RP-novices have a lot of difficulties in getting a global view of the RP technique and in tackling well founded decision for investment or outsourcing of RP tasks because of the very quick appearance of new and improved processes in this field. In order to help novices select a suitable RP process, the rapid prototyping system selector has been developed by many researchers [24–27]. Quickparts. com, which is a privately held manufacturing services company dedicated to providing

customers with an on-line E-commerce system to procure lowvolume and high-volume custom manufactured parts, has developed a QuickQuote system. The QuickQuote system enables customers to get instant, customerized quotations for the production of their parts [28]. 3D Systems Company, which is the earliest and biggest RP equipment manufacturer, has provided RP&M service for customer via Internet [29].

From these literatures survey, it is clear that most of studies mainly focused on the strategy and overall architecture of networked manufacturing as well as individual function module, there is still no comprehensive and banausic networked manufacturing service system to support rapid product development. Built on the emerging researches and our earlier work (e.g. Refs. [30,31]), a web-based manufacturing service system for rapid product development is to be established.

3. Architecture of the integrated system ofrapid product development

The development process from initial conceptual design to commercial product is an iterative process which includes: product design; analysis of performance, safety and reliability; product prototyping for experimental evaluation; and design modification. Therefore, any step of new product development process has a direct and strong influence on time-to-market. A good product development system must enable designers or design teams to consider all aspects of product design, manufacturing, selling and recycling at the early stage of a design cycle. So that design iteration and changes can be made easily and effectively. The more fluent the feedback is, the higher possibility success of the system has. Design for manufacturing (DFM) and concurrent engineering (CE) require that product and process design be developed simultaneously rather than sequentially [32].

The integrated system of rapid product development is composed of three modules: digital prototype, physical prototype and rapid tooling and functional part manufacturing system. The product development starts from the creation of a 3D model using a 3D 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 modelling. The product and its components are directly designed on a 3D CAD system (e.g. Pro/Engineer, Unigraphics, CATIA, IDEAS, etc.) during the creative design process. If a physical part is available, the model can be constructed by the reverse engineering (RE) 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 manufacturing components [33]. RE can reduce the development cycle when redesigns become necessary for improved product performance. Pre-existing parts with features for improved performance can be readily incorporated into the desired part design. 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 are part digitization, features extraction, and 3D CAD modelling. Part digitization is accomplished by a variety of contact or non-contact digitizers. There are various commercial systems available for part digitization. There systems range from coordinate measuring machine (CMM), laser scanners to ultrasonic 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 non-contact devices. Contact digitizers mainly have CMM and cross-sectional imaging measurement (CIM). Feature extraction is normally achieved by segmenting the digitized data and capturing surface features such as edges. Part modelling is fulfilled through fitting a variety of surface to the segmented data points [34]. In order to reduce the iterations of design-prototypetest cycles, increase the product process and manufacturing reliability, it is necessary to guide in optimization of the product design and manufacturing process through CAE.

The CAD model can be directly converted to the physical prototype using a RP technique. 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 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 inherent in conventional machining approaches [35]. RP potentially offers great benefits when used during the design and manufacturing process. It can help shorten time-to-market, improve quality and reduce cost. Over the last 10 years, RP machines have been widely used in industry. The RP methods commercially available include Stereolithgraphy (SL), Selective Laser Sintering (SLS), Fused Deposition Manufacturing (FDM), Laminated Object Manufacturing (LOM), Ballistic Particle Manufacturing (BMP), and Three Dimensional Printing (3D printing) [36], etc.

RTis a technique that transforms the RP patterns into functional parts, especially metal parts. Furthermore, the integration of both RP and RT in development strategy promotes the implementation of concurrent engineering in companies. Numerous processes have been developed for producing dies fromRP system. The RT methods can generally be divided into direct and indirect tooling categories, and also soft (firm) and hard tooling subgroups. Indirect RT requires some kinds of master patterns, which can be made by conventional methods (e.g. HSM), or more commonly by an RP process such as SL or SLS. Direct RT, as the name suggests, involves manufacturing a tool cavity directly on the RP system, hence eliminating the intermediate

step of generating a pattern [37]. On the basis of abovetechniques, a novel integrated system of rapid product development is to be established. Its detailed structure is shown in Fig. 1.

4. The workflow and function design

The workflow of the service system of networkedmanufacturing is shown in Fig.

2. The first step is to log in to the website of SB. Users have to enter their names and passwords. Those without registration or authorization can also enter into the system, but they are limited to viewing the information that is open to the public such as ‘‘typical cases’’ in this system. The password entered by the user will be verified by the system. After entering the SB website successfully, the system will check the security level of users, and determine which modules they can access or employ. According to authentication for the system, all usersa re to be divided into four categories: general users (without registration), potential clients, real clients, and system administrator. Received job requests from clients, the SB will perform firstly process planning which fulfills the task decomposition and selects the most suitable process methods. It is necessary for users to get the preliminary product quote and manufacturing time from the SB before the follow-up process continues. If such results may be accepted initially, The SB will negotiate further with users by Video-conferencing system. Once come to term each other, a contract is to be confirmed, and the user becomes a real client. The manufacturing tasks submitted by real clients had better be implemented in the SB. However, if the SB has no such manufacturing capabilities or can not accomplish then in time, it is an effective way that the SB takes full advantage of external sources to carry out the remaining tasks.

The next step is to select the appropriate collaborative manufacturing enterprises to form a virtual enterprise to complete the tasks by the task assignment decision system. In addition, in order to monitor the manufacturing schedule to ensure smooth production, both collaborative manufacturing enterprises and SB itself must provide as quickly as possible the essential information related to production progress and schedule for the module of production monitor. So any companies falling behind schedule or failing to meet quality standards will be closely examined by SB and users to ensure that precautionary or remedial measures are made ahead of time or any damaging effects are predicted.

Referring to the workflow of networked service system above and the functional requirement of the digital teleservice system, the service system consists of nine functional modules: the technique research, typical cases, information consultation, ASP (application service provider) tool set, client management,

Electronic commerce, manufacturing service, system navigation. Its detailed structure is shown in Fig. 3.

These nine components work together seamlessly to achieve the common objectives, i.e. to provide an effective and prompt service platform to support the rapid product development of SMEs. One of the purposes of the technique research is to enable users to increase awareness of the relevant knowledge of

rapid product development. In order to help users better understand and apply these new techniques, the system illustrates a number of real-life cases. Both the technique research and typical cases mainly provide self-help service for users. Depending on the predominance of specialty and expert, the SB can answer the queries of clients and communicate with novices to solve their problems by the information consultation module.

The ASP tool set provides five useful components below: the process planning of RE/RP/RT, STL checking and fixing, the optimization of part orientation, the support structure generation, and the optimization of part slicing. There are various process methods for RE, RP and RT as previously described, each of them has its characteristics and the scope of application. It is especially difficult for many novices to select the most suitable process methods according to the individual task requirement and condit ion. Three selectors based on ASP mode, namely, ‘‘RE selector’’, ‘‘RP selector’’, and ‘‘RT selector’’ have been developed to perform process planning automatically in the Web Serverside. In [38], Miller states that .STL files created from solid models have anomalies about 10% of the time and those created from surface models have problems about 90%of the time. Error rates in this range make it clear that automated error checking is important for all RP operations. Based on our experience with supplying network-based resources, we know that it is especially crucial to perform automatic error checking when the RP operation is not at the designer’s site. We have developed various algorithms to detect, and in some cases, automatically fix geometric and topologic al flaws. There are two ‘‘firewalls’’ to detect those flaws: one is integrated with the online pricing engine that will be operated by the user before the .STL file is submitted to the SB, while the other is to run on the SB’s Server-side after the .STL file is submitted. Because the function of fixing is quite restricted, if a .STL file has fatal flaws or loses some data during transferring, it would have to be uploaded again from the Client-side. Parts formed using RP technique can vary significantly in quality depending on the manufacturing process planning. The process planning of RP is performed to generate the tool paths and process parameters for a part that is to be built by a particular RP process. The steps required are the part orientation, support structure generation, slicing, path planning, and process parameter selection. Therefore, it is also very important for remote users that SB can provide these process planning techniques. Three sub-modules including the optimization of part orientation, support structure generation, and the optimization of part slicing, have been developed to aid effectively users in setting RP process variables in order to best achieve specific build goals and desired part characteristic. Both potential clients and real clients can employ freely the ASP tool set.

Electronic commerce module is composed of foursections: the online quote, build-time estimation, online business negotiation, and electronic contract management. Conventionally, the SB may quote according to the client’s offerings (e.g. CAD models, 2D drawings or physical prototypes) utilizing their experiences or just get payment after the RP model has been built. But for teleservice, it is

necessary for the remote users to inquire about the service expense of making RP prototype before the follow-up process continues. Hence, an online pricing engine (OPE) has been developed. The details of the OPE Stereolithography oriented have been discussed in [39]. The accurate prediction of the build-time required is also critical for various activities such as: the job quoting, the job scheduling, the selection of build parameters (e.g. layer thickness and orientation), benchmarking, etc. Two build-time estimators based on sliced process and STL have been exploited, respectively. Ref. [40] presents the principle of a build-time estimation algorithm for Stereolithograpy based on model geometrical features. After clients accept initially the quote, they may negotiate with SB on the business and technological details. The Microsoft NetMeeting which can set up a collaborative environment to fulfill information sharing, file transferring, Video and Audio communication etc., provides an ideal tool for the online negotiation. It is also seamlessly integrated IE Browser, thus clients can call SB at any moment. As a result of negotiation, an electronic contract is to be signed. To effectively manage andoperate these electronic contracts, the system alsoprovides a contract management component. It is especially convenient and prompt for clients to submit, inquire, and search contract through this module.

The manufacturing service module which covers the job management, collaborative manufacturing, process monitor, and collaborative enterprises management, is regarded as one of the most important function modules in the service system. When a contract is confirmed, clients will formally submit their job requirements (e.g. RE, 3D CAD modelling, CAE, RP prototype, or rapid tooling) and sources (e.g. object parts, digitized data cloud, 2D models, 3D models, or .STL files). In order to help many novices submit quickly and easy the manufacturing tasks, various job and source templates have been created, while the client can search, modify, and even delete the manufacturing tasks itself if the occasion arises. The Collaborative Manufacturing System (CMS) is responsible for the selection of collaborative enterprises (CE). In addition, it is extraordinarily important and necessary to monitor the manufacturing schedule and control product quality to ensure smooth production. In the past, a SB had to spend much time on dealing with a lot of inquires from the clients by via phone calls or Faxes. Now, the Process Monitor System (PMS) provides various facilities which canguarantee the tasks to be completed timely. Any partners falling behind schedule or failing to meet quality standards will be closely examined by SB and users to ensure that precautionary or remedial measures are made ahead of time or any damaging effects are predicted.

All information (no matter if it is a real client being ready for a contract with the SB or just a potential one showing his intent or inquiry) involved in the whole service process are managed and maintained by a special Database. These data provide strong supports for both online business and manufacturing service. To create a collaborative environment among SB, users and CE, we have to rely fully on the multimedia and Internet. Therefore, the service system offers three enabling tools: Video conferencing system, Electronic white-boarding, and FTP. In

order to make use of the system as quickly as possible, users can get help from the system navigation module. These nine components form a fully-integrated system that is able to carry out tasks in an efficient and effective way.

On the basis of the workflow and function module of service system, the system framework can be constructed as shown in Fig. 4. Fig. 5 illustrates the networked structure of service system.

5. Configuration of running platform

In order to run this system effectively, constructing asuitable running platform is necessary and especially crucial. An operating system (OS) is one of the most basic software components for running this system. The operating systems commonly founded onWeb Servers are UNIX, OS, Linux, and Windows, etc. Windows 2000 Advanced Server is a better platform for running business application. Better SMP scalability, improved networking performance, and support for more physical memory have a profound impact on the performance of Windows 2000 Advanced Server in an application server environment. Hence, we select Windows 2000 Advanced Server as the operating systemof the running platform. Web Servers including Apache, IIS, iPlanet, CERN, and IBM WebSphere, are frequently installed websites at the present time. Internet Information Services (IIS) 5.0 which is integratedWindows Advanced 2000 Server is a new release Web Server of Microsoft Company. Not only being a Server, it also provides a number of other Internet services such as FTP, News, WWW, and SMTP, etc. With tighter integration between the operating system and IIS, it offers performance gains and

higher availability for Web Servers and sites. Normally IIS can not execute Servlet and Java Server Pages (JSP), configuring IIS to use Tomcat redirector plugin will let IIS send Servlet, and JSP requests to Tomcat (and thisway, serve them to clients). Tomcat3.2 of the Apache Software Foundation is selected to act as the engine of JSP and Servlets. Database Server adopts SQL Server 2000 Relational Database. Exchange Server 5.5 is to be used to implement the mail service function. In order to prevent hacking system, two firewalls based on package filtration and proxy Server, namely, Cisico2511 router and Proxy Server 2.0, have been established. The overall configuration of Web platform is shown in Table 1.

6. Design of internet application

6.1. Browse/server model

The model of information service based on WWW falls into two broad categories: Client/Server (abbreviation C/S) and Browser/Server (B/S). C/S is a twotier model where a connection is built directly between the Client and Database Server. In comparison, B/S is a three-tier model where a connection is built between the Servlet or Application Server and Database Server, and the Clients obtain the data from the Servlet or Application Server. In the three-tier model, it is the middle tier of Servlet or Application Server objects that deal with all Database access operations. B/S has the same benefits (e.g. highly interactive, graphical user interface aids productivity) as C/S, but avoids the enormous distribution and maintenance problem. Besides an operating system and personal productivity software, the only software that the user-end needs, is a Web Browser that can run Java Applets. The B/S architecture allows developing professionals to focus on development and maintenance tasks on the Server side in spite of the increasing number of distributed customers. Therefore, there are a number of advantages for a B/S model: thin Client (platform independent), central software storage and control, high interactivity, economy in system development, maintenance and upgrade. Due to the distributed and heterogeneous nature of clients and collaborative enterprises, this service system is based on B/S structure which can fit the distributed and heterogeneous environment of networked manufacturing. The structure of B/S model is shown in Fig. 6.

6.2. Choosing a server-side language

Creating dynamic Web pages that interact with the user showing customized information is the pith of Web application for B/S model. With the rapid development and prevalence of Internet, a variety of solutions have appeared which enables the development of Web application to become more and more simple, convenient and effective. Four Server-side scripting languages including Common Gateway Interface (CGI), Active Server Pages (ASP), Person Home Pages (PHP), and Java Server Pages (JSP), are frequently used now.

CGI scripts are inefficient and difficult to be used for writing Server extensions. Each time someone hits a CGI script, a new process is created on the Server; if a script is written in an interpreted language like Perl, the Server has to start up another Perl interpreter, consuming more processing time and memory. The

situation gets even worsewhen it resides on a site that is getting a few thousand hits a day. Another disadvantage with CGI is that a CGI program can not interact with the Web Server during its execution because it is running in a separate process. Microsoft attempted to change all this when they introduced Active Server Pages, which allows developers to use simple scripting to access the Server and its extensions. ASP is almost as efficient as writing code directly to the Server’s application program interface, and it is more efficient than CGI because it runs as a service and can take advantage of multithreaded architectures. But while ASP provides an efficient way to return dynamic content, it essentiallylimits one to Microsoft platforms, and even the

simplest of scripting mistakes can crash or hang the Web Server [41]. PHP is an open-source Server-side scripting language for creating dynamicWeb pages for Web applications. A particular strength is that it can be used to develop Websites on a desktop system and deploy then on secure Servers such as those found commonly only running UNIX or Linux. The PHP drawbacks that we have found are predominantly in its weak abstraction for Databases (each Database backend is accessed through a different interface. In other words, PHP is limited to using a small handful of free Database APIs, none of which are compatible with each other), underdeveloped library mechanism (lacking Peril’s true ‘‘module’’ concept) and occasional linguistic quirks [42].

In response to ASP, Sun Microsystems gave the world Java Server Pages (JSP) technology, which is based entirely upon Sun’s popular Java programming language and gives developers the advantages of developing in Java in a more

relaxed, script-like environment. JSP is a better solution generating dynamicWeb pages in contrast to ASP, PHP, and CGI. Together, JSP and Servlets provide an attractive alternative to other types of dynamic Web scripting/programming that offers platform independence, enhanced performance, separation of logic fromdisplay, ease of administration, extensibility into the enterprise and most importantly, ease of use [43]. JSP/Servlets has been widely applied by many electronic commerce providers such as the famous E-Business. EJBtJSPtServlets are almost to be a standard of developing electronic commerce. Hence, it is a better decision to develop dynamic Web pages by JSP and Servlets.

6.3. Constructing development platform

The running and development environment of JSP and Servlets is especially complicated. The running

and development framework of JSP and Servlets is described in Fig. 7. The application development platform is shown in Table 2. The development kits of application are reported in Table 3. Figs. 8–11 illustrate the Home page,Web page for manufacturing service, Web page for remote STL checking, and Web page for client management. The web page for user interface of online pricing engine (OPE) in Internet Explorer 5.0 and a case of online quote are illustrated in Figs. 12 and 13 respectively.

7. Case study

To illustrate exactly how the service system works and the benefits it can bring to the users and servicebureaus, an actual example is now presented. Let us assume that a company was working on a new design of the curing coryza apparatus for which a number of physical models would be required. The model was purely for the purpose of design visualization and would be used as a means of communication with other functional departments in the organization. The task requirement and relevant resources were submitted to SB by the job management module of the service system. After receiving the job requirement, the system would firstly perform the process planning by which the job was to be decomposed into the 3D CAD modelling and making prototype, and SL wasselected as the most suitable process for building the mock-ups through the ‘‘RP selector’’, while the service system offered the preliminary product quote and manufacturing time for the user. Accepted initially such results, the user continued to negotiate further with SB by Video-conferencing system. Once a commercial, a contract was to be confirmed in the end. Subsequently, the 3D CAD modelling and prototype making were assigned to the Shaanxi Productivity Promote Center and Chongqi Productivity Promote Center respectively to complete. Finally, the green parts would be checked online and delivered to the end user. The detailed workflow is represented in Fig. 14. The result of process planning is reported in Table 4. The 3D CAD models submitted by the Shaanxi Productivity Promote Center are illustrated in Fig. 15. The mock-ups fabricated by the Chongqi Productivity Promote Center are shown in Fig. 16. In contrast to the traditional development mode, it can cut the new product costs by up to 50% and the timeto- market by 75%. Consequently, the costs and lead times are substantially reduced using this service system to develop new products.

8. Conclusions and future research

In order to meet the current demand of rapid product development, a novel integrated system of rapid product development based on rapid prototyping is proposed, and a networked service system which offers better support for the rapid product development of small and medium sized enterprises is established.

A Java solution is used for constructing the networked manufacturing service system based on the three-tier Browser/Server mode. Since Java technology is introduced to this research, the infrastructure can be easily extended into a standard JINI computing model in the future. The service system which includes the technology information platform, E-commerce platform, and manufacturing service platform, provides a production collaborative environment for users and service bureaus, enables the share of manufacturing resource and can effectively aid the rapid product development of small and medium sized enterprises. This system has been employing in the Northwest Productivity Promotion Center. It has been shown from a number of case studies that the system has a high potential to speed up the new product development. As a result, the implementation of such a system will represent afundamental shift of enterprise strategy and manufacturing paradigms in organization.