Fig。 1。  The general procedure of mould design  [1]。

Researchers have started to adopt a knowledge-based approach to solve the injection moulding and mould design problems in recent years。 DTMOULD-1 [14] is a KBS for of injection moulds cost estimation。 EIMPPLAN-1 [15] incorporated mouldability considerations into part designs and addressed the conceptual design development of injection-moulded parts。 CADFEED [16] was developed for injection mould design。 They are, however, limited to specific design areas or simple parts, and are not mature and  practical  enough  to  cover  general  mould      design。

Bozdana and Eyercioglu [17] developed an expert system for the determination of injection moulding parameters of thermoplastic materials。 Chan et al。 [18] presented the basic structure of a CAD knowledge-based assisted injection mould design system which covers both the mould design process and mould knowledge  management。

From the above review it can be seen that most of the previous work consider only certain aspects of the total design and some of them are too theoretical to be applied for  practical  mould  design  which  involves  a  substantial

practical knowledge component about functions and structure of a mould, human heuristic knowledge and empirical type of knowledge。 The KB system has demon- strated great potential to assist the designer to interact with a CAD system for conceptualized design as well as the final engineering design of a mould by using engineering rules of thumb with extensive analytical means。 In addition, there is still relatively few research works on Internet-based intelligent system for injection mould  design。

4。 Architecture  of the Internet-based  mould  design system

4。1。 Overview

At the present time, most CAD systems provide only the geometric modelling functions which facilitate the drafting operations of mould design, and do not provide mould designers with necessary knowledge to develop good mould designs。 Conventional computer-aided engineering packages are usually good at data processing for informa- tion-intensive problems or at number manipulation for formulation-intensive problems。 The former comprehends the computer-aided drafting and graphics, and data reduction and transformation; while the latter involves numerical (or mathematical) modelling and analysis。 However, in design problem, especially in mould design which involves a substantial practical knowledge compo- nent about functions and structure of a mould, human heuristic knowledge and empirical type of knowledge are needed   in   addition   to   the   information-intensive    and

formulation-intensive knowledge。 Therefore, conventional computer-aided design technology is unsuitable for proces- sing heuristic and empirical type of knowledge which is critical in the mould design problems。 In general, the major advantage of the KB system for mould design over conventional computer-aided design systems is the explicit representation and manipulation of a body of knowledge, representing the human  expertise。

An Internet-based mould design system using Internet technology and knowledge-based approach can provide an effective and feasible tool to aid the collaborative develop- ment of injection moulds in the small- and medium-sized enterprises to satisfy the stringent requirements of nowadays competitive global market。 Moreover, there is a consistent need to check and update the information to ensure that the data is accurate and updated as mould manufacturers and standard components suppliers continually improve and upgrade their equipments and processes。 By taking full advantage of the fast evolving computer network and information technologies, an Internet-based mould design system could have the ability to continually update and upgrade the large amount of information related to injection mould design in a prompt and convenient  manner。