3。2。3 The detailed mould design

In the detailed mould design, the IKB-MOULD is developed for three different and useful applications for use by the mould design companies: the design for assembly, the design for a 2D drawing and the design for BOM。

(1) The design for assembly。 An injection mould is a mechanical assembly that is composed of the product- independent and product-dependent parts。 Design of the product-dependent parts is based on the geometry extracted from the plastic product。 This extraction can be realised by integrating some automation algorithms and expert knowledge。 The design of product-independent parts is based on the designer’s experience and catalogue information。

Tasks in the detailed injection mould design may be interrelated with many of the injection mould objects’ design elements。 Therefore, the final detailed mould design can be regarded as a design composed of the injection mould objects。 Representation of an injection mould object and the knowledge used for detailed mould design is explained in a later section。 Based on that representation, an assembly tree can be automatically generated and modified during the detail mould design。 (2) The design for manufacture。 This module is developed mainly for the CAPP/CNC of the final designed mould。 In process planning, the sequence of machining processes to manufacture the designed

mould is a complicated task and requires manufacturing knowledge。 Manufacturing features needed to be abstracted from the final designed mould and a relative sequenced process has to be generated based on knowledge stored in the knowledge base。 In addition, a tool library for the specific NC machine is used to automatically

generate the NC code for the manufacturing process。 Detailed design of the manufacture module in the IKB-MOULD is not presented in this paper。 (3) The design for the 2D drawing。 With the help of an application-programming-interface (API) providedby the commercial solid modelling software, most2D drawings of parts can be obtained from the solidmodel。 Some intelligent tools need to be developedfor generating detailed dimensions。(4) The design for the bill of material (BOM)。 Similarto the design for the assembly in the detailed moulddesign, all properties of the designed injectionmould objects can be traced。 A tool can be developedto automatically generate the BOM。

3。3 Knowledge base and libraries

3。3。1 Knowledge representation

Knowledge for an injection mould design is gained mainly through experience and handbooks。 Each module of the mould design process needs to be supported by the knowledge base。 Knowledge involved in the mould development can be represented in terms of design rules: IF (conditions) THEN (design solution)。 Some design rules in the IKB-MOULD used to determine the ejector pin size from both the catalogue library and design experience are represented as

follows:

Rule 1 : IF ejector pin type is Straight circular type

AND ejector pin size = 1。0mm

THEN ejector pin head dia= 3。0mm;

ejector pin head thick = 4。0mm

Rule 2 : IF ejector pin type is Step type

AND ejector pin size = 0。4mm

THEN ejector pin head dia = 2。0mm;

ejector pin head thick =4。0mm;

ejector pin step dia =0。5mm;

ejector pin step lengh =20。0mm

Rule 3 : IF ejector pin type is Rectangular type

AND ejector pin size =1。8x3。0mm

THEN ejector pin head dia = 15。0mm;

ejector pin head thick = 4。0mm;

Ejector pin step dia = 10。0mm;

ejector pin step lengh = 20。0mm

Rule 4 : IF Mouldbase = TRUE

AND Core insert = TRUE

THEN Ejector pin length

= （z co - ordinate of product ejection point at core）-（z co - ordinate of ejector back plate base）

In the IKB-MOULD, knowledge rules are stored in groups that are associated with the design tasks。 Many  design tasks in the mould design module are shown in